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TOMOYO Linux Cross Reference
Linux/arch/Kconfig

Version: ~ [ linux-6.11.5 ] ~ [ linux-6.10.14 ] ~ [ linux-6.9.12 ] ~ [ linux-6.8.12 ] ~ [ linux-6.7.12 ] ~ [ linux-6.6.58 ] ~ [ linux-6.5.13 ] ~ [ linux-6.4.16 ] ~ [ linux-6.3.13 ] ~ [ linux-6.2.16 ] ~ [ linux-6.1.114 ] ~ [ linux-6.0.19 ] ~ [ linux-5.19.17 ] ~ [ linux-5.18.19 ] ~ [ linux-5.17.15 ] ~ [ linux-5.16.20 ] ~ [ linux-5.15.169 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.228 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.284 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.322 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.336 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.337 ] ~ [ linux-4.4.302 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.9 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

Diff markup

Differences between /arch/Kconfig (Version linux-6.11.5) and /arch/Kconfig (Version linux-5.18.19)


  1 # SPDX-License-Identifier: GPL-2.0                  1 # SPDX-License-Identifier: GPL-2.0
  2 #                                                   2 #
  3 # General architecture dependent options            3 # General architecture dependent options
  4 #                                                   4 #
  5                                                     5 
  6 #                                                   6 #
  7 # Note: arch/$(SRCARCH)/Kconfig needs to be in      7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
  8 # override the default values in this file.         8 # override the default values in this file.
  9 #                                                   9 #
 10 source "arch/$(SRCARCH)/Kconfig"                   10 source "arch/$(SRCARCH)/Kconfig"
 11                                                    11 
 12 config ARCH_CONFIGURES_CPU_MITIGATIONS         << 
 13         bool                                   << 
 14                                                << 
 15 if !ARCH_CONFIGURES_CPU_MITIGATIONS            << 
 16 config CPU_MITIGATIONS                         << 
 17         def_bool y                             << 
 18 endif                                          << 
 19                                                << 
 20 menu "General architecture-dependent options"      12 menu "General architecture-dependent options"
 21                                                    13 
 22 config ARCH_HAS_SUBPAGE_FAULTS                 !!  14 config CRASH_CORE
 23         bool                                   << 
 24         help                                   << 
 25           Select if the architecture can check << 
 26           granularity (e.g. arm64 MTE). The pr << 
 27           must be implemented.                 << 
 28                                                << 
 29 config HOTPLUG_SMT                             << 
 30         bool                                   << 
 31                                                << 
 32 config SMT_NUM_THREADS_DYNAMIC                 << 
 33         bool                                   << 
 34                                                << 
 35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU << 
 36 config HOTPLUG_CORE_SYNC                       << 
 37         bool                                       15         bool
 38                                                    16 
 39 # Basic CPU dead synchronization selected by a !!  17 config KEXEC_CORE
 40 config HOTPLUG_CORE_SYNC_DEAD                  !!  18         select CRASH_CORE
 41         bool                                       19         bool
 42         select HOTPLUG_CORE_SYNC               << 
 43                                                    20 
 44 # Full CPU synchronization with alive state se !!  21 config KEXEC_ELF
 45 config HOTPLUG_CORE_SYNC_FULL                  << 
 46         bool                                       22         bool
 47         select HOTPLUG_CORE_SYNC_DEAD if HOTPL << 
 48         select HOTPLUG_CORE_SYNC               << 
 49                                                    23 
 50 config HOTPLUG_SPLIT_STARTUP                   !!  24 config HAVE_IMA_KEXEC
 51         bool                                       25         bool
 52         select HOTPLUG_CORE_SYNC_FULL          << 
 53                                                    26 
 54 config HOTPLUG_PARALLEL                        !!  27 config HOTPLUG_SMT
 55         bool                                       28         bool
 56         select HOTPLUG_SPLIT_STARTUP           << 
 57                                                    29 
 58 config GENERIC_ENTRY                               30 config GENERIC_ENTRY
 59         bool                                   !!  31        bool
 60                                                    32 
 61 config KPROBES                                     33 config KPROBES
 62         bool "Kprobes"                             34         bool "Kprobes"
                                                   >>  35         depends on MODULES
 63         depends on HAVE_KPROBES                    36         depends on HAVE_KPROBES
 64         select KALLSYMS                            37         select KALLSYMS
 65         select EXECMEM                         << 
 66         select NEED_TASKS_RCU                  << 
 67         help                                       38         help
 68           Kprobes allows you to trap at almost     39           Kprobes allows you to trap at almost any kernel address and
 69           execute a callback function.  regist     40           execute a callback function.  register_kprobe() establishes
 70           a probepoint and specifies the callb     41           a probepoint and specifies the callback.  Kprobes is useful
 71           for kernel debugging, non-intrusive      42           for kernel debugging, non-intrusive instrumentation and testing.
 72           If in doubt, say "N".                    43           If in doubt, say "N".
 73                                                    44 
 74 config JUMP_LABEL                                  45 config JUMP_LABEL
 75         bool "Optimize very unlikely/likely br     46         bool "Optimize very unlikely/likely branches"
 76         depends on HAVE_ARCH_JUMP_LABEL            47         depends on HAVE_ARCH_JUMP_LABEL
 77         select OBJTOOL if HAVE_JUMP_LABEL_HACK !!  48         depends on CC_HAS_ASM_GOTO
 78         help                                       49         help
 79           This option enables a transparent br !!  50          This option enables a transparent branch optimization that
 80           makes certain almost-always-true or  !!  51          makes certain almost-always-true or almost-always-false branch
 81           conditions even cheaper to execute w !!  52          conditions even cheaper to execute within the kernel.
 82                                                !!  53 
 83           Certain performance-sensitive kernel !!  54          Certain performance-sensitive kernel code, such as trace points,
 84           scheduler functionality, networking  !!  55          scheduler functionality, networking code and KVM have such
 85           branches and include support for thi !!  56          branches and include support for this optimization technique.
 86                                                !!  57 
 87           If it is detected that the compiler  !!  58          If it is detected that the compiler has support for "asm goto",
 88           the kernel will compile such branche !!  59          the kernel will compile such branches with just a nop
 89           instruction. When the condition flag !!  60          instruction. When the condition flag is toggled to true, the
 90           nop will be converted to a jump inst !!  61          nop will be converted to a jump instruction to execute the
 91           conditional block of instructions.   !!  62          conditional block of instructions.
 92                                                !!  63 
 93           This technique lowers overhead and s !!  64          This technique lowers overhead and stress on the branch prediction
 94           of the processor and generally makes !!  65          of the processor and generally makes the kernel faster. The update
 95           of the condition is slower, but thos !!  66          of the condition is slower, but those are always very rare.
 96                                                    67 
 97           ( On 32-bit x86, the necessary optio !!  68          ( On 32-bit x86, the necessary options added to the compiler
 98             flags may increase the size of the !!  69            flags may increase the size of the kernel slightly. )
 99                                                    70 
100 config STATIC_KEYS_SELFTEST                        71 config STATIC_KEYS_SELFTEST
101         bool "Static key selftest"                 72         bool "Static key selftest"
102         depends on JUMP_LABEL                      73         depends on JUMP_LABEL
103         help                                       74         help
104           Boot time self-test of the branch pa     75           Boot time self-test of the branch patching code.
105                                                    76 
106 config STATIC_CALL_SELFTEST                        77 config STATIC_CALL_SELFTEST
107         bool "Static call selftest"                78         bool "Static call selftest"
108         depends on HAVE_STATIC_CALL                79         depends on HAVE_STATIC_CALL
109         help                                       80         help
110           Boot time self-test of the call patc     81           Boot time self-test of the call patching code.
111                                                    82 
112 config OPTPROBES                                   83 config OPTPROBES
113         def_bool y                                 84         def_bool y
114         depends on KPROBES && HAVE_OPTPROBES       85         depends on KPROBES && HAVE_OPTPROBES
115         select NEED_TASKS_RCU                  !!  86         select TASKS_RCU if PREEMPTION
116                                                    87 
117 config KPROBES_ON_FTRACE                           88 config KPROBES_ON_FTRACE
118         def_bool y                                 89         def_bool y
119         depends on KPROBES && HAVE_KPROBES_ON_     90         depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120         depends on DYNAMIC_FTRACE_WITH_REGS        91         depends on DYNAMIC_FTRACE_WITH_REGS
121         help                                       92         help
122           If function tracer is enabled and th !!  93          If function tracer is enabled and the arch supports full
123           passing of pt_regs to function traci !!  94          passing of pt_regs to function tracing, then kprobes can
124           optimize on top of function tracing. !!  95          optimize on top of function tracing.
125                                                    96 
126 config UPROBES                                     97 config UPROBES
127         def_bool n                                 98         def_bool n
128         depends on ARCH_SUPPORTS_UPROBES           99         depends on ARCH_SUPPORTS_UPROBES
129         help                                      100         help
130           Uprobes is the user-space counterpar    101           Uprobes is the user-space counterpart to kprobes: they
131           enable instrumentation applications     102           enable instrumentation applications (such as 'perf probe')
132           to establish unintrusive probes in u    103           to establish unintrusive probes in user-space binaries and
133           libraries, by executing handler func    104           libraries, by executing handler functions when the probes
134           are hit by user-space applications.     105           are hit by user-space applications.
135                                                   106 
136           ( These probes come in the form of s    107           ( These probes come in the form of single-byte breakpoints,
137             managed by the kernel and kept tra    108             managed by the kernel and kept transparent to the probed
138             application. )                        109             application. )
139                                                   110 
140 config HAVE_64BIT_ALIGNED_ACCESS                  111 config HAVE_64BIT_ALIGNED_ACCESS
141         def_bool 64BIT && !HAVE_EFFICIENT_UNAL    112         def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142         help                                      113         help
143           Some architectures require 64 bit ac    114           Some architectures require 64 bit accesses to be 64 bit
144           aligned, which also requires structs    115           aligned, which also requires structs containing 64 bit values
145           to be 64 bit aligned too. This inclu    116           to be 64 bit aligned too. This includes some 32 bit
146           architectures which can do 64 bit ac    117           architectures which can do 64 bit accesses, as well as 64 bit
147           architectures without unaligned acce    118           architectures without unaligned access.
148                                                   119 
149           This symbol should be selected by an    120           This symbol should be selected by an architecture if 64 bit
150           accesses are required to be 64 bit a    121           accesses are required to be 64 bit aligned in this way even
151           though it is not a 64 bit architectu    122           though it is not a 64 bit architecture.
152                                                   123 
153           See Documentation/core-api/unaligned    124           See Documentation/core-api/unaligned-memory-access.rst for
154           more information on the topic of una    125           more information on the topic of unaligned memory accesses.
155                                                   126 
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS            127 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157         bool                                      128         bool
158         help                                      129         help
159           Some architectures are unable to per    130           Some architectures are unable to perform unaligned accesses
160           without the use of get_unaligned/put    131           without the use of get_unaligned/put_unaligned. Others are
161           unable to perform such accesses effi    132           unable to perform such accesses efficiently (e.g. trap on
162           unaligned access and require fixing     133           unaligned access and require fixing it up in the exception
163           handler.)                               134           handler.)
164                                                   135 
165           This symbol should be selected by an    136           This symbol should be selected by an architecture if it can
166           perform unaligned accesses efficient    137           perform unaligned accesses efficiently to allow different
167           code paths to be selected for these     138           code paths to be selected for these cases. Some network
168           drivers, for example, could opt to n    139           drivers, for example, could opt to not fix up alignment
169           problems with received packets if do    140           problems with received packets if doing so would not help
170           much.                                   141           much.
171                                                   142 
172           See Documentation/core-api/unaligned    143           See Documentation/core-api/unaligned-memory-access.rst for more
173           information on the topic of unaligne    144           information on the topic of unaligned memory accesses.
174                                                   145 
175 config ARCH_USE_BUILTIN_BSWAP                     146 config ARCH_USE_BUILTIN_BSWAP
176         bool                                      147         bool
177         help                                      148         help
178           Modern versions of GCC (since 4.4) h !! 149          Modern versions of GCC (since 4.4) have builtin functions
179           for handling byte-swapping. Using th !! 150          for handling byte-swapping. Using these, instead of the old
180           inline assembler that the architectu !! 151          inline assembler that the architecture code provides in the
181           __arch_bswapXX() macros, allows the  !! 152          __arch_bswapXX() macros, allows the compiler to see what's
182           happening and offers more opportunit !! 153          happening and offers more opportunity for optimisation. In
183           particular, the compiler will be abl !! 154          particular, the compiler will be able to combine the byteswap
184           with a nearby load or store and use  !! 155          with a nearby load or store and use load-and-swap or
185           store-and-swap instructions if the a !! 156          store-and-swap instructions if the architecture has them. It
186           should almost *never* result in code !! 157          should almost *never* result in code which is worse than the
187           hand-coded assembler in <asm/swab.h> !! 158          hand-coded assembler in <asm/swab.h>.  But just in case it
188           does, the use of the builtins is opt !! 159          does, the use of the builtins is optional.
189                                                !! 160 
190           Any architecture with load-and-swap  !! 161          Any architecture with load-and-swap or store-and-swap
191           instructions should set this. And it !! 162          instructions should set this. And it shouldn't hurt to set it
192           on architectures that don't have suc !! 163          on architectures that don't have such instructions.
193                                                   164 
194 config KRETPROBES                                 165 config KRETPROBES
195         def_bool y                                166         def_bool y
196         depends on KPROBES && (HAVE_KRETPROBES    167         depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
197                                                   168 
198 config KRETPROBE_ON_RETHOOK                       169 config KRETPROBE_ON_RETHOOK
199         def_bool y                                170         def_bool y
200         depends on HAVE_RETHOOK                   171         depends on HAVE_RETHOOK
201         depends on KRETPROBES                     172         depends on KRETPROBES
202         select RETHOOK                            173         select RETHOOK
203                                                   174 
204 config USER_RETURN_NOTIFIER                       175 config USER_RETURN_NOTIFIER
205         bool                                      176         bool
206         depends on HAVE_USER_RETURN_NOTIFIER      177         depends on HAVE_USER_RETURN_NOTIFIER
207         help                                      178         help
208           Provide a kernel-internal notificati    179           Provide a kernel-internal notification when a cpu is about to
209           switch to user mode.                    180           switch to user mode.
210                                                   181 
211 config HAVE_IOREMAP_PROT                          182 config HAVE_IOREMAP_PROT
212         bool                                      183         bool
213                                                   184 
214 config HAVE_KPROBES                               185 config HAVE_KPROBES
215         bool                                      186         bool
216                                                   187 
217 config HAVE_KRETPROBES                            188 config HAVE_KRETPROBES
218         bool                                      189         bool
219                                                   190 
220 config HAVE_OPTPROBES                             191 config HAVE_OPTPROBES
221         bool                                      192         bool
222                                                   193 
223 config HAVE_KPROBES_ON_FTRACE                     194 config HAVE_KPROBES_ON_FTRACE
224         bool                                      195         bool
225                                                   196 
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE       197 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
227         bool                                      198         bool
228         help                                      199         help
229           Since kretprobes modifies return add    200           Since kretprobes modifies return address on the stack, the
230           stacktrace may see the kretprobe tra    201           stacktrace may see the kretprobe trampoline address instead
231           of correct one. If the architecture     202           of correct one. If the architecture stacktrace code and
232           unwinder can adjust such entries, se    203           unwinder can adjust such entries, select this configuration.
233                                                   204 
234 config HAVE_FUNCTION_ERROR_INJECTION              205 config HAVE_FUNCTION_ERROR_INJECTION
235         bool                                      206         bool
236                                                   207 
237 config HAVE_NMI                                   208 config HAVE_NMI
238         bool                                      209         bool
239                                                   210 
240 config HAVE_FUNCTION_DESCRIPTORS                  211 config HAVE_FUNCTION_DESCRIPTORS
241         bool                                      212         bool
242                                                   213 
243 config TRACE_IRQFLAGS_SUPPORT                     214 config TRACE_IRQFLAGS_SUPPORT
244         bool                                      215         bool
245                                                   216 
246 config TRACE_IRQFLAGS_NMI_SUPPORT                 217 config TRACE_IRQFLAGS_NMI_SUPPORT
247         bool                                      218         bool
248                                                   219 
249 #                                                 220 #
250 # An arch should select this if it provides al    221 # An arch should select this if it provides all these things:
251 #                                                 222 #
252 #       task_pt_regs()          in asm/process    223 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
253 #       arch_has_single_step()  if there is ha    224 #       arch_has_single_step()  if there is hardware single-step support
254 #       arch_has_block_step()   if there is ha    225 #       arch_has_block_step()   if there is hardware block-step support
255 #       asm/syscall.h           supplying asm-    226 #       asm/syscall.h           supplying asm-generic/syscall.h interface
256 #       linux/regset.h          user_regset in    227 #       linux/regset.h          user_regset interfaces
257 #       CORE_DUMP_USE_REGSET    #define'd in l    228 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
258 #       TIF_SYSCALL_TRACE       calls ptrace_r    229 #       TIF_SYSCALL_TRACE       calls ptrace_report_syscall_{entry,exit}
259 #       TIF_NOTIFY_RESUME       calls resume_u    230 #       TIF_NOTIFY_RESUME       calls resume_user_mode_work()
260 #                                                 231 #
261 config HAVE_ARCH_TRACEHOOK                        232 config HAVE_ARCH_TRACEHOOK
262         bool                                      233         bool
263                                                   234 
264 config HAVE_DMA_CONTIGUOUS                        235 config HAVE_DMA_CONTIGUOUS
265         bool                                      236         bool
266                                                   237 
267 config GENERIC_SMP_IDLE_THREAD                    238 config GENERIC_SMP_IDLE_THREAD
268         bool                                      239         bool
269                                                   240 
270 config GENERIC_IDLE_POLL_SETUP                    241 config GENERIC_IDLE_POLL_SETUP
271         bool                                      242         bool
272                                                   243 
273 config ARCH_HAS_FORTIFY_SOURCE                    244 config ARCH_HAS_FORTIFY_SOURCE
274         bool                                      245         bool
275         help                                      246         help
276           An architecture should select this w    247           An architecture should select this when it can successfully
277           build and run with CONFIG_FORTIFY_SO    248           build and run with CONFIG_FORTIFY_SOURCE.
278                                                   249 
279 #                                                 250 #
280 # Select if the arch provides a historic keepi    251 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option                             252 # command line option
282 #                                                 253 #
283 config ARCH_HAS_KEEPINITRD                        254 config ARCH_HAS_KEEPINITRD
284         bool                                      255         bool
285                                                   256 
286 # Select if arch has all set_memory_ro/rw/x/nx    257 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY                        258 config ARCH_HAS_SET_MEMORY
288         bool                                      259         bool
289                                                   260 
290 # Select if arch has all set_direct_map_invali    261 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP                    262 config ARCH_HAS_SET_DIRECT_MAP
292         bool                                      263         bool
293                                                   264 
294 #                                                 265 #
295 # Select if the architecture provides the arch    266 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for    267 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place.              268 # to remap the page tables in place.
298 #                                                 269 #
299 config ARCH_HAS_DMA_SET_UNCACHED                  270 config ARCH_HAS_DMA_SET_UNCACHED
300         bool                                      271         bool
301                                                   272 
302 #                                                 273 #
303 # Select if the architectures provides the arc    274 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc    275 # to undo an in-place page table remap for uncached access.
305 #                                                 276 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED                277 config ARCH_HAS_DMA_CLEAR_UNCACHED
307         bool                                      278         bool
308                                                   279 
309 config ARCH_HAS_CPU_FINALIZE_INIT              !! 280 # Select if arch init_task must go in the __init_task_data section
                                                   >> 281 config ARCH_TASK_STRUCT_ON_STACK
310         bool                                      282         bool
311                                                   283 
312 # The architecture has a per-task state that i !! 284 # Select if arch has its private alloc_task_struct() function
313 config ARCH_HAS_CPU_PASID                      !! 285 config ARCH_TASK_STRUCT_ALLOCATOR
314         bool                                      286         bool
315         select IOMMU_MM_DATA                   << 
316                                                   287 
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST          288 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318         bool                                      289         bool
                                                   >> 290         depends on !ARCH_TASK_STRUCT_ALLOCATOR
319         help                                      291         help
320           An architecture should select this t    292           An architecture should select this to provide hardened usercopy
321           knowledge about what region of the t    293           knowledge about what region of the thread_struct should be
322           whitelisted for copying to userspace    294           whitelisted for copying to userspace. Normally this is only the
323           FPU registers. Specifically, arch_th    295           FPU registers. Specifically, arch_thread_struct_whitelist()
324           should be implemented. Without this,    296           should be implemented. Without this, the entire thread_struct
325           field in task_struct will be left wh    297           field in task_struct will be left whitelisted.
326                                                   298 
                                                   >> 299 # Select if arch has its private alloc_thread_stack() function
                                                   >> 300 config ARCH_THREAD_STACK_ALLOCATOR
                                                   >> 301         bool
                                                   >> 302 
327 # Select if arch wants to size task_struct dyn    303 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT             304 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
329         bool                                      305         bool
330                                                   306 
331 config ARCH_WANTS_NO_INSTR                        307 config ARCH_WANTS_NO_INSTR
332         bool                                      308         bool
333         help                                      309         help
334           An architecture should select this i    310           An architecture should select this if the noinstr macro is being used on
335           functions to denote that the toolcha    311           functions to denote that the toolchain should avoid instrumenting such
336           functions and is required for correc    312           functions and is required for correctness.
337                                                   313 
338 config ARCH_32BIT_OFF_T                           314 config ARCH_32BIT_OFF_T
339         bool                                      315         bool
340         depends on !64BIT                         316         depends on !64BIT
341         help                                      317         help
342           All new 32-bit architectures should     318           All new 32-bit architectures should have 64-bit off_t type on
343           userspace side which corresponds to     319           userspace side which corresponds to the loff_t kernel type. This
344           is the requirement for modern ABIs.     320           is the requirement for modern ABIs. Some existing architectures
345           still support 32-bit off_t. This opt    321           still support 32-bit off_t. This option is enabled for all such
346           architectures explicitly.               322           architectures explicitly.
347                                                   323 
348 # Selected by 64 bit architectures which have     324 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349 config ARCH_32BIT_USTAT_F_TINODE                  325 config ARCH_32BIT_USTAT_F_TINODE
350         bool                                      326         bool
351                                                   327 
352 config HAVE_ASM_MODVERSIONS                       328 config HAVE_ASM_MODVERSIONS
353         bool                                      329         bool
354         help                                      330         help
355           This symbol should be selected by an    331           This symbol should be selected by an architecture if it provides
356           <asm/asm-prototypes.h> to support th    332           <asm/asm-prototypes.h> to support the module versioning for symbols
357           exported from assembly code.            333           exported from assembly code.
358                                                   334 
359 config HAVE_REGS_AND_STACK_ACCESS_API             335 config HAVE_REGS_AND_STACK_ACCESS_API
360         bool                                      336         bool
361         help                                      337         help
362           This symbol should be selected by an    338           This symbol should be selected by an architecture if it supports
363           the API needed to access registers a    339           the API needed to access registers and stack entries from pt_regs,
364           declared in asm/ptrace.h                340           declared in asm/ptrace.h
365           For example the kprobes-based event     341           For example the kprobes-based event tracer needs this API.
366                                                   342 
367 config HAVE_RSEQ                                  343 config HAVE_RSEQ
368         bool                                      344         bool
369         depends on HAVE_REGS_AND_STACK_ACCESS_    345         depends on HAVE_REGS_AND_STACK_ACCESS_API
370         help                                      346         help
371           This symbol should be selected by an    347           This symbol should be selected by an architecture if it
372           supports an implementation of restar    348           supports an implementation of restartable sequences.
373                                                   349 
374 config HAVE_RUST                               << 
375         bool                                   << 
376         help                                   << 
377           This symbol should be selected by an << 
378           supports Rust.                       << 
379                                                << 
380 config HAVE_FUNCTION_ARG_ACCESS_API               350 config HAVE_FUNCTION_ARG_ACCESS_API
381         bool                                      351         bool
382         help                                      352         help
383           This symbol should be selected by an    353           This symbol should be selected by an architecture if it supports
384           the API needed to access function ar    354           the API needed to access function arguments from pt_regs,
385           declared in asm/ptrace.h                355           declared in asm/ptrace.h
386                                                   356 
387 config HAVE_HW_BREAKPOINT                         357 config HAVE_HW_BREAKPOINT
388         bool                                      358         bool
389         depends on PERF_EVENTS                    359         depends on PERF_EVENTS
390                                                   360 
391 config HAVE_MIXED_BREAKPOINTS_REGS                361 config HAVE_MIXED_BREAKPOINTS_REGS
392         bool                                      362         bool
393         depends on HAVE_HW_BREAKPOINT             363         depends on HAVE_HW_BREAKPOINT
394         help                                      364         help
395           Depending on the arch implementation    365           Depending on the arch implementation of hardware breakpoints,
396           some of them have separate registers    366           some of them have separate registers for data and instruction
397           breakpoints addresses, others have m    367           breakpoints addresses, others have mixed registers to store
398           them but define the access type in a    368           them but define the access type in a control register.
399           Select this option if your arch impl    369           Select this option if your arch implements breakpoints under the
400           latter fashion.                         370           latter fashion.
401                                                   371 
402 config HAVE_USER_RETURN_NOTIFIER                  372 config HAVE_USER_RETURN_NOTIFIER
403         bool                                      373         bool
404                                                   374 
405 config HAVE_PERF_EVENTS_NMI                       375 config HAVE_PERF_EVENTS_NMI
406         bool                                      376         bool
407         help                                      377         help
408           System hardware can generate an NMI     378           System hardware can generate an NMI using the perf event
409           subsystem.  Also has support for cal    379           subsystem.  Also has support for calculating CPU cycle events
410           to determine how many clock cycles i    380           to determine how many clock cycles in a given period.
411                                                   381 
412 config HAVE_HARDLOCKUP_DETECTOR_PERF              382 config HAVE_HARDLOCKUP_DETECTOR_PERF
413         bool                                      383         bool
414         depends on HAVE_PERF_EVENTS_NMI           384         depends on HAVE_PERF_EVENTS_NMI
415         help                                      385         help
416           The arch chooses to use the generic     386           The arch chooses to use the generic perf-NMI-based hardlockup
417           detector. Must define HAVE_PERF_EVEN    387           detector. Must define HAVE_PERF_EVENTS_NMI.
418                                                   388 
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH           !! 389 config HAVE_NMI_WATCHDOG
                                                   >> 390         depends on HAVE_NMI
420         bool                                      391         bool
421         help                                      392         help
422           The arch provides its own hardlockup !! 393           The arch provides a low level NMI watchdog. It provides
423           of the generic ones.                 !! 394           asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424                                                   395 
425           It uses the same command line parame !! 396 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426           as the generic hardlockup detectors. !! 397         bool
                                                   >> 398         select HAVE_NMI_WATCHDOG
                                                   >> 399         help
                                                   >> 400           The arch chooses to provide its own hardlockup detector, which is
                                                   >> 401           a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
                                                   >> 402           interfaces and parameters provided by hardlockup detector subsystem.
427                                                   403 
428 config HAVE_PERF_REGS                             404 config HAVE_PERF_REGS
429         bool                                      405         bool
430         help                                      406         help
431           Support selective register dumps for    407           Support selective register dumps for perf events. This includes
432           bit-mapping of each registers and a     408           bit-mapping of each registers and a unique architecture id.
433                                                   409 
434 config HAVE_PERF_USER_STACK_DUMP                  410 config HAVE_PERF_USER_STACK_DUMP
435         bool                                      411         bool
436         help                                      412         help
437           Support user stack dumps for perf ev    413           Support user stack dumps for perf event samples. This needs
438           access to the user stack pointer whi    414           access to the user stack pointer which is not unified across
439           architectures.                          415           architectures.
440                                                   416 
441 config HAVE_ARCH_JUMP_LABEL                       417 config HAVE_ARCH_JUMP_LABEL
442         bool                                      418         bool
443                                                   419 
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE              420 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445         bool                                      421         bool
446                                                   422 
447 config MMU_GATHER_TABLE_FREE                      423 config MMU_GATHER_TABLE_FREE
448         bool                                      424         bool
449                                                   425 
450 config MMU_GATHER_RCU_TABLE_FREE                  426 config MMU_GATHER_RCU_TABLE_FREE
451         bool                                      427         bool
452         select MMU_GATHER_TABLE_FREE              428         select MMU_GATHER_TABLE_FREE
453                                                   429 
454 config MMU_GATHER_PAGE_SIZE                       430 config MMU_GATHER_PAGE_SIZE
455         bool                                      431         bool
456                                                   432 
457 config MMU_GATHER_NO_RANGE                        433 config MMU_GATHER_NO_RANGE
458         bool                                      434         bool
459         select MMU_GATHER_MERGE_VMAS           << 
460                                                << 
461 config MMU_GATHER_NO_FLUSH_CACHE               << 
462         bool                                   << 
463                                                << 
464 config MMU_GATHER_MERGE_VMAS                   << 
465         bool                                   << 
466                                                   435 
467 config MMU_GATHER_NO_GATHER                       436 config MMU_GATHER_NO_GATHER
468         bool                                      437         bool
469         depends on MMU_GATHER_TABLE_FREE          438         depends on MMU_GATHER_TABLE_FREE
470                                                   439 
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM             440 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472         bool                                      441         bool
473         help                                      442         help
474           Temporary select until all architect    443           Temporary select until all architectures can be converted to have
475           irqs disabled over activate_mm. Arch    444           irqs disabled over activate_mm. Architectures that do IPI based TLB
476           shootdowns should enable this.          445           shootdowns should enable this.
477                                                   446 
478 # Use normal mm refcounting for MMU_LAZY_TLB k << 
479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal << 
480 # to/from kernel threads when the same mm is r << 
481 # multi-threaded application), by reducing con << 
482 #                                              << 
483 # This can be disabled if the architecture ens << 
484 # "lazy tlb" beyond its final refcount (i.e.,  << 
485 # or its kernel page tables). This could be ar << 
486 # final exit(2) TLB flush, for example.        << 
487 #                                              << 
488 # To implement this, an arch *must*:           << 
489 # Ensure the _lazy_tlb variants of mmgrab/mmdr << 
490 # the lazy tlb reference of a kthread's ->acti << 
491 # converted already).                          << 
492 config MMU_LAZY_TLB_REFCOUNT                   << 
493         def_bool y                             << 
494         depends on !MMU_LAZY_TLB_SHOOTDOWN     << 
495                                                << 
496 # This option allows MMU_LAZY_TLB_REFCOUNT=n.  << 
497 # mm as a lazy tlb beyond its last reference c << 
498 # users before the mm is deallocated. __mmdrop << 
499 # be using the mm as a lazy tlb, so that they  << 
500 # init_mm for their active mm. mm_cpumask(mm)  << 
501 # may be using mm as a lazy tlb mm.            << 
502 #                                              << 
503 # To implement this, an arch *must*:           << 
504 # - At the time of the final mmdrop of the mm, << 
505 #   at least all possible CPUs in which the mm << 
506 # - It must meet the requirements for MMU_LAZY << 
507 config MMU_LAZY_TLB_SHOOTDOWN                  << 
508         bool                                   << 
509                                                << 
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG                 447 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511         bool                                      448         bool
512                                                   449 
513 config ARCH_HAVE_EXTRA_ELF_NOTES               << 
514         bool                                   << 
515         help                                   << 
516           An architecture should select this i << 
517           arch-specific ELF note section to co << 
518           functions: elf_coredump_extra_notes_ << 
519           elf_coredump_extra_notes_write() whi << 
520           dumper.                              << 
521                                                << 
522 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS          << 
523         bool                                   << 
524                                                << 
525 config HAVE_ALIGNED_STRUCT_PAGE                   450 config HAVE_ALIGNED_STRUCT_PAGE
526         bool                                      451         bool
527         help                                      452         help
528           This makes sure that struct pages ar    453           This makes sure that struct pages are double word aligned and that
529           e.g. the SLUB allocator can perform     454           e.g. the SLUB allocator can perform double word atomic operations
530           on a struct page for better performa    455           on a struct page for better performance. However selecting this
531           might increase the size of a struct     456           might increase the size of a struct page by a word.
532                                                   457 
533 config HAVE_CMPXCHG_LOCAL                         458 config HAVE_CMPXCHG_LOCAL
534         bool                                      459         bool
535                                                   460 
536 config HAVE_CMPXCHG_DOUBLE                        461 config HAVE_CMPXCHG_DOUBLE
537         bool                                      462         bool
538                                                   463 
539 config ARCH_WEAK_RELEASE_ACQUIRE                  464 config ARCH_WEAK_RELEASE_ACQUIRE
540         bool                                      465         bool
541                                                   466 
542 config ARCH_WANT_IPC_PARSE_VERSION                467 config ARCH_WANT_IPC_PARSE_VERSION
543         bool                                      468         bool
544                                                   469 
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION         470 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546         bool                                      471         bool
547                                                   472 
548 config ARCH_WANT_OLD_COMPAT_IPC                   473 config ARCH_WANT_OLD_COMPAT_IPC
549         select ARCH_WANT_COMPAT_IPC_PARSE_VERS    474         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550         bool                                      475         bool
551                                                   476 
552 config HAVE_ARCH_SECCOMP                          477 config HAVE_ARCH_SECCOMP
553         bool                                      478         bool
554         help                                      479         help
555           An arch should select this symbol to    480           An arch should select this symbol to support seccomp mode 1 (the fixed
556           syscall policy), and must provide an    481           syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557           and compat syscalls if the asm-gener    482           and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558           - __NR_seccomp_read_32                  483           - __NR_seccomp_read_32
559           - __NR_seccomp_write_32                 484           - __NR_seccomp_write_32
560           - __NR_seccomp_exit_32                  485           - __NR_seccomp_exit_32
561           - __NR_seccomp_sigreturn_32             486           - __NR_seccomp_sigreturn_32
562                                                   487 
563 config HAVE_ARCH_SECCOMP_FILTER                   488 config HAVE_ARCH_SECCOMP_FILTER
564         bool                                      489         bool
565         select HAVE_ARCH_SECCOMP                  490         select HAVE_ARCH_SECCOMP
566         help                                      491         help
567           An arch should select this symbol if    492           An arch should select this symbol if it provides all of these things:
568           - all the requirements for HAVE_ARCH    493           - all the requirements for HAVE_ARCH_SECCOMP
569           - syscall_get_arch()                    494           - syscall_get_arch()
570           - syscall_get_arguments()               495           - syscall_get_arguments()
571           - syscall_rollback()                    496           - syscall_rollback()
572           - syscall_set_return_value()            497           - syscall_set_return_value()
573           - SIGSYS siginfo_t support              498           - SIGSYS siginfo_t support
574           - secure_computing is called from a     499           - secure_computing is called from a ptrace_event()-safe context
575           - secure_computing return value is c    500           - secure_computing return value is checked and a return value of -1
576             results in the system call being s    501             results in the system call being skipped immediately.
577           - seccomp syscall wired up              502           - seccomp syscall wired up
578           - if !HAVE_SPARSE_SYSCALL_NR, have S    503           - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579             SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR    504             SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580             COMPAT is supported, have the SECC    505             COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581                                                   506 
582 config SECCOMP                                    507 config SECCOMP
583         prompt "Enable seccomp to safely execu    508         prompt "Enable seccomp to safely execute untrusted bytecode"
584         def_bool y                                509         def_bool y
585         depends on HAVE_ARCH_SECCOMP              510         depends on HAVE_ARCH_SECCOMP
586         help                                      511         help
587           This kernel feature is useful for nu    512           This kernel feature is useful for number crunching applications
588           that may need to handle untrusted by    513           that may need to handle untrusted bytecode during their
589           execution. By using pipes or other t    514           execution. By using pipes or other transports made available
590           to the process as file descriptors s    515           to the process as file descriptors supporting the read/write
591           syscalls, it's possible to isolate t    516           syscalls, it's possible to isolate those applications in their
592           own address space using seccomp. Onc    517           own address space using seccomp. Once seccomp is enabled via
593           prctl(PR_SET_SECCOMP) or the seccomp    518           prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594           disabled and the task is only allowe    519           disabled and the task is only allowed to execute a few safe
595           syscalls defined by each seccomp mod    520           syscalls defined by each seccomp mode.
596                                                   521 
597           If unsure, say Y.                       522           If unsure, say Y.
598                                                   523 
599 config SECCOMP_FILTER                             524 config SECCOMP_FILTER
600         def_bool y                                525         def_bool y
601         depends on HAVE_ARCH_SECCOMP_FILTER &&    526         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602         help                                      527         help
603           Enable tasks to build secure computi    528           Enable tasks to build secure computing environments defined
604           in terms of Berkeley Packet Filter p    529           in terms of Berkeley Packet Filter programs which implement
605           task-defined system call filtering p    530           task-defined system call filtering polices.
606                                                   531 
607           See Documentation/userspace-api/secc    532           See Documentation/userspace-api/seccomp_filter.rst for details.
608                                                   533 
609 config SECCOMP_CACHE_DEBUG                        534 config SECCOMP_CACHE_DEBUG
610         bool "Show seccomp filter cache status    535         bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611         depends on SECCOMP_FILTER && !HAVE_SPA    536         depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612         depends on PROC_FS                        537         depends on PROC_FS
613         help                                      538         help
614           This enables the /proc/pid/seccomp_c    539           This enables the /proc/pid/seccomp_cache interface to monitor
615           seccomp cache data. The file format     540           seccomp cache data. The file format is subject to change. Reading
616           the file requires CAP_SYS_ADMIN.        541           the file requires CAP_SYS_ADMIN.
617                                                   542 
618           This option is for debugging only. E    543           This option is for debugging only. Enabling presents the risk that
619           an adversary may be able to infer th    544           an adversary may be able to infer the seccomp filter logic.
620                                                   545 
621           If unsure, say N.                       546           If unsure, say N.
622                                                   547 
623 config HAVE_ARCH_STACKLEAK                        548 config HAVE_ARCH_STACKLEAK
624         bool                                      549         bool
625         help                                      550         help
626           An architecture should select this i    551           An architecture should select this if it has the code which
627           fills the used part of the kernel st    552           fills the used part of the kernel stack with the STACKLEAK_POISON
628           value before returning from system c    553           value before returning from system calls.
629                                                   554 
630 config HAVE_STACKPROTECTOR                        555 config HAVE_STACKPROTECTOR
631         bool                                      556         bool
632         help                                      557         help
633           An arch should select this symbol if    558           An arch should select this symbol if:
634           - it has implemented a stack canary     559           - it has implemented a stack canary (e.g. __stack_chk_guard)
635                                                   560 
636 config STACKPROTECTOR                             561 config STACKPROTECTOR
637         bool "Stack Protector buffer overflow     562         bool "Stack Protector buffer overflow detection"
638         depends on HAVE_STACKPROTECTOR            563         depends on HAVE_STACKPROTECTOR
639         depends on $(cc-option,-fstack-protect    564         depends on $(cc-option,-fstack-protector)
640         default y                                 565         default y
641         help                                      566         help
642           This option turns on the "stack-prot    567           This option turns on the "stack-protector" GCC feature. This
643           feature puts, at the beginning of fu    568           feature puts, at the beginning of functions, a canary value on
644           the stack just before the return add    569           the stack just before the return address, and validates
645           the value just before actually retur    570           the value just before actually returning.  Stack based buffer
646           overflows (that need to overwrite th    571           overflows (that need to overwrite this return address) now also
647           overwrite the canary, which gets det    572           overwrite the canary, which gets detected and the attack is then
648           neutralized via a kernel panic.         573           neutralized via a kernel panic.
649                                                   574 
650           Functions will have the stack-protec    575           Functions will have the stack-protector canary logic added if they
651           have an 8-byte or larger character a    576           have an 8-byte or larger character array on the stack.
652                                                   577 
653           This feature requires gcc version 4.    578           This feature requires gcc version 4.2 or above, or a distribution
654           gcc with the feature backported ("-f    579           gcc with the feature backported ("-fstack-protector").
655                                                   580 
656           On an x86 "defconfig" build, this fe    581           On an x86 "defconfig" build, this feature adds canary checks to
657           about 3% of all kernel functions, wh    582           about 3% of all kernel functions, which increases kernel code size
658           by about 0.3%.                          583           by about 0.3%.
659                                                   584 
660 config STACKPROTECTOR_STRONG                      585 config STACKPROTECTOR_STRONG
661         bool "Strong Stack Protector"             586         bool "Strong Stack Protector"
662         depends on STACKPROTECTOR                 587         depends on STACKPROTECTOR
663         depends on $(cc-option,-fstack-protect    588         depends on $(cc-option,-fstack-protector-strong)
664         default y                                 589         default y
665         help                                      590         help
666           Functions will have the stack-protec    591           Functions will have the stack-protector canary logic added in any
667           of the following conditions:            592           of the following conditions:
668                                                   593 
669           - local variable's address used as p    594           - local variable's address used as part of the right hand side of an
670             assignment or function argument       595             assignment or function argument
671           - local variable is an array (or uni    596           - local variable is an array (or union containing an array),
672             regardless of array type or length    597             regardless of array type or length
673           - uses register local variables         598           - uses register local variables
674                                                   599 
675           This feature requires gcc version 4.    600           This feature requires gcc version 4.9 or above, or a distribution
676           gcc with the feature backported ("-f    601           gcc with the feature backported ("-fstack-protector-strong").
677                                                   602 
678           On an x86 "defconfig" build, this fe    603           On an x86 "defconfig" build, this feature adds canary checks to
679           about 20% of all kernel functions, w    604           about 20% of all kernel functions, which increases the kernel code
680           size by about 2%.                       605           size by about 2%.
681                                                   606 
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK            607 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683         bool                                      608         bool
684         help                                      609         help
685           An architecture should select this i    610           An architecture should select this if it supports the compiler's
686           Shadow Call Stack and implements run    611           Shadow Call Stack and implements runtime support for shadow stack
687           switching.                              612           switching.
688                                                   613 
689 config SHADOW_CALL_STACK                          614 config SHADOW_CALL_STACK
690         bool "Shadow Call Stack"                  615         bool "Shadow Call Stack"
691         depends on ARCH_SUPPORTS_SHADOW_CALL_S    616         depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
692         depends on DYNAMIC_FTRACE_WITH_ARGS || !! 617         depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693         depends on MMU                         << 
694         help                                      618         help
695           This option enables the compiler's S    619           This option enables the compiler's Shadow Call Stack, which
696           uses a shadow stack to protect funct    620           uses a shadow stack to protect function return addresses from
697           being overwritten by an attacker. Mo    621           being overwritten by an attacker. More information can be found
698           in the compiler's documentation:        622           in the compiler's documentation:
699                                                   623 
700           - Clang: https://clang.llvm.org/docs    624           - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
701           - GCC: https://gcc.gnu.org/onlinedoc    625           - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
702                                                   626 
703           Note that security guarantees in the    627           Note that security guarantees in the kernel differ from the
704           ones documented for user space. The     628           ones documented for user space. The kernel must store addresses
705           of shadow stacks in memory, which me    629           of shadow stacks in memory, which means an attacker capable of
706           reading and writing arbitrary memory    630           reading and writing arbitrary memory may be able to locate them
707           and hijack control flow by modifying    631           and hijack control flow by modifying the stacks.
708                                                   632 
709 config DYNAMIC_SCS                             << 
710         bool                                   << 
711         help                                   << 
712           Set by the arch code if it relies on << 
713           shadow call stack push and pop instr << 
714           compiler.                            << 
715                                                << 
716 config LTO                                        633 config LTO
717         bool                                      634         bool
718         help                                      635         help
719           Selected if the kernel will be built    636           Selected if the kernel will be built using the compiler's LTO feature.
720                                                   637 
721 config LTO_CLANG                                  638 config LTO_CLANG
722         bool                                      639         bool
723         select LTO                                640         select LTO
724         help                                      641         help
725           Selected if the kernel will be built    642           Selected if the kernel will be built using Clang's LTO feature.
726                                                   643 
727 config ARCH_SUPPORTS_LTO_CLANG                    644 config ARCH_SUPPORTS_LTO_CLANG
728         bool                                      645         bool
729         help                                      646         help
730           An architecture should select this o    647           An architecture should select this option if it supports:
731           - compiling with Clang,                 648           - compiling with Clang,
732           - compiling inline assembly with Cla    649           - compiling inline assembly with Clang's integrated assembler,
733           - and linking with LLD.                 650           - and linking with LLD.
734                                                   651 
735 config ARCH_SUPPORTS_LTO_CLANG_THIN               652 config ARCH_SUPPORTS_LTO_CLANG_THIN
736         bool                                      653         bool
737         help                                      654         help
738           An architecture should select this o    655           An architecture should select this option if it can support Clang's
739           ThinLTO mode.                           656           ThinLTO mode.
740                                                   657 
741 config HAS_LTO_CLANG                              658 config HAS_LTO_CLANG
742         def_bool y                                659         def_bool y
743         depends on CC_IS_CLANG && LD_IS_LLD &&    660         depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
744         depends on $(success,$(NM) --help | he    661         depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745         depends on $(success,$(AR) --help | he    662         depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746         depends on ARCH_SUPPORTS_LTO_CLANG        663         depends on ARCH_SUPPORTS_LTO_CLANG
747         depends on !FTRACE_MCOUNT_USE_RECORDMC    664         depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748         # https://github.com/ClangBuiltLinux/l !! 665         depends on !KASAN || KASAN_HW_TAGS
749         depends on (!KASAN || KASAN_HW_TAGS || << 
750         depends on (!KCOV || CLANG_VERSION >=  << 
751         depends on !GCOV_KERNEL                   666         depends on !GCOV_KERNEL
752         help                                      667         help
753           The compiler and Kconfig options sup    668           The compiler and Kconfig options support building with Clang's
754           LTO.                                    669           LTO.
755                                                   670 
756 choice                                            671 choice
757         prompt "Link Time Optimization (LTO)"     672         prompt "Link Time Optimization (LTO)"
758         default LTO_NONE                          673         default LTO_NONE
759         help                                      674         help
760           This option enables Link Time Optimi    675           This option enables Link Time Optimization (LTO), which allows the
761           compiler to optimize binaries global    676           compiler to optimize binaries globally.
762                                                   677 
763           If unsure, select LTO_NONE. Note tha    678           If unsure, select LTO_NONE. Note that LTO is very resource-intensive
764           so it's disabled by default.            679           so it's disabled by default.
765                                                   680 
766 config LTO_NONE                                   681 config LTO_NONE
767         bool "None"                               682         bool "None"
768         help                                      683         help
769           Build the kernel normally, without L    684           Build the kernel normally, without Link Time Optimization (LTO).
770                                                   685 
771 config LTO_CLANG_FULL                             686 config LTO_CLANG_FULL
772         bool "Clang Full LTO (EXPERIMENTAL)"      687         bool "Clang Full LTO (EXPERIMENTAL)"
773         depends on HAS_LTO_CLANG                  688         depends on HAS_LTO_CLANG
774         depends on !COMPILE_TEST                  689         depends on !COMPILE_TEST
775         select LTO_CLANG                          690         select LTO_CLANG
776         help                                      691         help
777           This option enables Clang's full Lin !! 692           This option enables Clang's full Link Time Optimization (LTO), which
778           allows the compiler to optimize the  !! 693           allows the compiler to optimize the kernel globally. If you enable
779           this option, the compiler generates  !! 694           this option, the compiler generates LLVM bitcode instead of ELF
780           object files, and the actual compila !! 695           object files, and the actual compilation from bitcode happens at
781           the LTO link step, which may take se !! 696           the LTO link step, which may take several minutes depending on the
782           kernel configuration. More informati !! 697           kernel configuration. More information can be found from LLVM's
783           documentation:                       !! 698           documentation:
784                                                   699 
785             https://llvm.org/docs/LinkTimeOpti    700             https://llvm.org/docs/LinkTimeOptimization.html
786                                                   701 
787           During link time, this option can us    702           During link time, this option can use a large amount of RAM, and
788           may take much longer than the ThinLT    703           may take much longer than the ThinLTO option.
789                                                   704 
790 config LTO_CLANG_THIN                             705 config LTO_CLANG_THIN
791         bool "Clang ThinLTO (EXPERIMENTAL)"       706         bool "Clang ThinLTO (EXPERIMENTAL)"
792         depends on HAS_LTO_CLANG && ARCH_SUPPO    707         depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
793         select LTO_CLANG                          708         select LTO_CLANG
794         help                                      709         help
795           This option enables Clang's ThinLTO,    710           This option enables Clang's ThinLTO, which allows for parallel
796           optimization and faster incremental     711           optimization and faster incremental compiles compared to the
797           CONFIG_LTO_CLANG_FULL option. More i    712           CONFIG_LTO_CLANG_FULL option. More information can be found
798           from Clang's documentation:             713           from Clang's documentation:
799                                                   714 
800             https://clang.llvm.org/docs/ThinLT    715             https://clang.llvm.org/docs/ThinLTO.html
801                                                   716 
802           If unsure, say Y.                       717           If unsure, say Y.
803 endchoice                                         718 endchoice
804                                                   719 
805 config ARCH_SUPPORTS_CFI_CLANG                    720 config ARCH_SUPPORTS_CFI_CLANG
806         bool                                      721         bool
807         help                                      722         help
808           An architecture should select this o    723           An architecture should select this option if it can support Clang's
809           Control-Flow Integrity (CFI) checkin    724           Control-Flow Integrity (CFI) checking.
810                                                   725 
811 config ARCH_USES_CFI_TRAPS                     << 
812         bool                                   << 
813                                                << 
814 config CFI_CLANG                                  726 config CFI_CLANG
815         bool "Use Clang's Control Flow Integri    727         bool "Use Clang's Control Flow Integrity (CFI)"
816         depends on ARCH_SUPPORTS_CFI_CLANG     !! 728         depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
817         depends on $(cc-option,-fsanitize=kcfi !! 729         # Clang >= 12:
                                                   >> 730         # - https://bugs.llvm.org/show_bug.cgi?id=46258
                                                   >> 731         # - https://bugs.llvm.org/show_bug.cgi?id=47479
                                                   >> 732         depends on CLANG_VERSION >= 120000
                                                   >> 733         select KALLSYMS
818         help                                      734         help
819           This option enables Clang's forward- !! 735           This option enables Clang’s forward-edge Control Flow Integrity
820           (CFI) checking, where the compiler i    736           (CFI) checking, where the compiler injects a runtime check to each
821           indirect function call to ensure the    737           indirect function call to ensure the target is a valid function with
822           the correct static type. This restri    738           the correct static type. This restricts possible call targets and
823           makes it more difficult for an attac    739           makes it more difficult for an attacker to exploit bugs that allow
824           the modification of stored function     740           the modification of stored function pointers. More information can be
825           found from Clang's documentation:       741           found from Clang's documentation:
826                                                   742 
827             https://clang.llvm.org/docs/Contro    743             https://clang.llvm.org/docs/ControlFlowIntegrity.html
828                                                   744 
                                                   >> 745 config CFI_CLANG_SHADOW
                                                   >> 746         bool "Use CFI shadow to speed up cross-module checks"
                                                   >> 747         default y
                                                   >> 748         depends on CFI_CLANG && MODULES
                                                   >> 749         help
                                                   >> 750           If you select this option, the kernel builds a fast look-up table of
                                                   >> 751           CFI check functions in loaded modules to reduce performance overhead.
                                                   >> 752 
                                                   >> 753           If unsure, say Y.
                                                   >> 754 
829 config CFI_PERMISSIVE                             755 config CFI_PERMISSIVE
830         bool "Use CFI in permissive mode"         756         bool "Use CFI in permissive mode"
831         depends on CFI_CLANG                      757         depends on CFI_CLANG
832         help                                      758         help
833           When selected, Control Flow Integrit    759           When selected, Control Flow Integrity (CFI) violations result in a
834           warning instead of a kernel panic. T    760           warning instead of a kernel panic. This option should only be used
835           for finding indirect call type misma    761           for finding indirect call type mismatches during development.
836                                                   762 
837           If unsure, say N.                       763           If unsure, say N.
838                                                   764 
839 config HAVE_ARCH_WITHIN_STACK_FRAMES              765 config HAVE_ARCH_WITHIN_STACK_FRAMES
840         bool                                      766         bool
841         help                                      767         help
842           An architecture should select this i    768           An architecture should select this if it can walk the kernel stack
843           frames to determine if an object is     769           frames to determine if an object is part of either the arguments
844           or local variables (i.e. that it exc    770           or local variables (i.e. that it excludes saved return addresses,
845           and similar) by implementing an inli    771           and similar) by implementing an inline arch_within_stack_frames(),
846           which is used by CONFIG_HARDENED_USE    772           which is used by CONFIG_HARDENED_USERCOPY.
847                                                   773 
848 config HAVE_CONTEXT_TRACKING_USER              !! 774 config HAVE_CONTEXT_TRACKING
849         bool                                      775         bool
850         help                                      776         help
851           Provide kernel/user boundaries probe    777           Provide kernel/user boundaries probes necessary for subsystems
852           that need it, such as userspace RCU     778           that need it, such as userspace RCU extended quiescent state.
853           Syscalls need to be wrapped inside u    779           Syscalls need to be wrapped inside user_exit()-user_enter(), either
854           optimized behind static key or throu    780           optimized behind static key or through the slow path using TIF_NOHZ
855           flag. Exceptions handlers must be wr    781           flag. Exceptions handlers must be wrapped as well. Irqs are already
856           protected inside ct_irq_enter/ct_irq !! 782           protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
857           handling on irq exit still need to b    783           handling on irq exit still need to be protected.
858                                                   784 
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK     !! 785 config HAVE_CONTEXT_TRACKING_OFFSTACK
860         bool                                      786         bool
861         help                                      787         help
862           Architecture neither relies on excep    788           Architecture neither relies on exception_enter()/exception_exit()
863           nor on schedule_user(). Also preempt    789           nor on schedule_user(). Also preempt_schedule_notrace() and
864           preempt_schedule_irq() can't be call    790           preempt_schedule_irq() can't be called in a preemptible section
865           while context tracking is CONTEXT_US    791           while context tracking is CONTEXT_USER. This feature reflects a sane
866           entry implementation where the follo    792           entry implementation where the following requirements are met on
867           critical entry code, ie: before user    793           critical entry code, ie: before user_exit() or after user_enter():
868                                                   794 
869           - Critical entry code isn't preempti    795           - Critical entry code isn't preemptible (or better yet:
870             not interruptible).                   796             not interruptible).
871           - No use of RCU read side critical s !! 797           - No use of RCU read side critical sections, unless rcu_nmi_enter()
872             got called.                           798             got called.
873           - No use of instrumentation, unless     799           - No use of instrumentation, unless instrumentation_begin() got
874             called.                               800             called.
875                                                   801 
876 config HAVE_TIF_NOHZ                              802 config HAVE_TIF_NOHZ
877         bool                                      803         bool
878         help                                      804         help
879           Arch relies on TIF_NOHZ and syscall     805           Arch relies on TIF_NOHZ and syscall slow path to implement context
880           tracking calls to user_enter()/user_    806           tracking calls to user_enter()/user_exit().
881                                                   807 
882 config HAVE_VIRT_CPU_ACCOUNTING                   808 config HAVE_VIRT_CPU_ACCOUNTING
883         bool                                      809         bool
884                                                   810 
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE              811 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886         bool                                      812         bool
887         help                                      813         help
888           Architecture has its own way to acco    814           Architecture has its own way to account idle CPU time and therefore
889           doesn't implement vtime_account_idle    815           doesn't implement vtime_account_idle().
890                                                   816 
891 config ARCH_HAS_SCALED_CPUTIME                    817 config ARCH_HAS_SCALED_CPUTIME
892         bool                                      818         bool
893                                                   819 
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN               820 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895         bool                                      821         bool
896         default y if 64BIT                        822         default y if 64BIT
897         help                                      823         help
898           With VIRT_CPU_ACCOUNTING_GEN, cputim    824           With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899           Before enabling this option, arch co    825           Before enabling this option, arch code must be audited
900           to ensure there are no races in conc    826           to ensure there are no races in concurrent read/write of
901           cputime_t. For example, reading/writ    827           cputime_t. For example, reading/writing 64-bit cputime_t on
902           some 32-bit arches may require multi    828           some 32-bit arches may require multiple accesses, so proper
903           locking is needed to protect against    829           locking is needed to protect against concurrent accesses.
904                                                   830 
905 config HAVE_IRQ_TIME_ACCOUNTING                   831 config HAVE_IRQ_TIME_ACCOUNTING
906         bool                                      832         bool
907         help                                      833         help
908           Archs need to ensure they use a high    834           Archs need to ensure they use a high enough resolution clock to
909           support irq time accounting and then    835           support irq time accounting and then call enable_sched_clock_irqtime().
910                                                   836 
911 config HAVE_MOVE_PUD                              837 config HAVE_MOVE_PUD
912         bool                                      838         bool
913         help                                      839         help
914           Architectures that select this are a    840           Architectures that select this are able to move page tables at the
915           PUD level. If there are only 3 page     841           PUD level. If there are only 3 page table levels, the move effectively
916           happens at the PGD level.               842           happens at the PGD level.
917                                                   843 
918 config HAVE_MOVE_PMD                              844 config HAVE_MOVE_PMD
919         bool                                      845         bool
920         help                                      846         help
921           Archs that select this are able to m    847           Archs that select this are able to move page tables at the PMD level.
922                                                   848 
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE             849 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924         bool                                      850         bool
925                                                   851 
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD         852 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927         bool                                      853         bool
928                                                   854 
929 config HAVE_ARCH_HUGE_VMAP                        855 config HAVE_ARCH_HUGE_VMAP
930         bool                                      856         bool
931                                                   857 
932 #                                                 858 #
933 #  Archs that select this would be capable of     859 #  Archs that select this would be capable of PMD-sized vmaps (i.e.,
934 #  arch_vmap_pmd_supported() returns true). Th    860 #  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
935 #  must be used to enable allocations to use h    861 #  must be used to enable allocations to use hugepages.
936 #                                                 862 #
937 config HAVE_ARCH_HUGE_VMALLOC                     863 config HAVE_ARCH_HUGE_VMALLOC
938         depends on HAVE_ARCH_HUGE_VMAP            864         depends on HAVE_ARCH_HUGE_VMAP
939         bool                                      865         bool
940                                                   866 
941 config ARCH_WANT_HUGE_PMD_SHARE                   867 config ARCH_WANT_HUGE_PMD_SHARE
942         bool                                      868         bool
943                                                   869 
944 # Archs that want to use pmd_mkwrite on kernel << 
945 # if there are no userspace memory management  << 
946 config ARCH_WANT_KERNEL_PMD_MKWRITE            << 
947         bool                                   << 
948                                                << 
949 config ARCH_WANT_PMD_MKWRITE                   << 
950         def_bool TRANSPARENT_HUGEPAGE || ARCH_ << 
951                                                << 
952 config HAVE_ARCH_SOFT_DIRTY                       870 config HAVE_ARCH_SOFT_DIRTY
953         bool                                      871         bool
954                                                   872 
955 config HAVE_MOD_ARCH_SPECIFIC                     873 config HAVE_MOD_ARCH_SPECIFIC
956         bool                                      874         bool
957         help                                      875         help
958           The arch uses struct mod_arch_specif    876           The arch uses struct mod_arch_specific to store data.  Many arches
959           just need a simple module loader wit    877           just need a simple module loader without arch specific data - those
960           should not enable this.                 878           should not enable this.
961                                                   879 
962 config MODULES_USE_ELF_RELA                       880 config MODULES_USE_ELF_RELA
963         bool                                      881         bool
964         help                                      882         help
965           Modules only use ELF RELA relocation    883           Modules only use ELF RELA relocations.  Modules with ELF REL
966           relocations will give an error.         884           relocations will give an error.
967                                                   885 
968 config MODULES_USE_ELF_REL                        886 config MODULES_USE_ELF_REL
969         bool                                      887         bool
970         help                                      888         help
971           Modules only use ELF REL relocations    889           Modules only use ELF REL relocations.  Modules with ELF RELA
972           relocations will give an error.         890           relocations will give an error.
973                                                   891 
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC      << 
975         bool                                   << 
976         help                                   << 
977           For architectures like powerpc/32 wh << 
978           allocation and need to allocate modu << 
979                                                << 
980 config ARCH_WANTS_EXECMEM_LATE                 << 
981         bool                                   << 
982         help                                   << 
983           For architectures that do not alloca << 
984           boot, but rather require its initial << 
985           enough entropy for module space rand << 
986           arm64.                               << 
987                                                << 
988 config HAVE_IRQ_EXIT_ON_IRQ_STACK                 892 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989         bool                                      893         bool
990         help                                      894         help
991           Architecture doesn't only execute th    895           Architecture doesn't only execute the irq handler on the irq stack
992           but also irq_exit(). This way we can    896           but also irq_exit(). This way we can process softirqs on this irq
993           stack instead of switching to a new     897           stack instead of switching to a new one when we call __do_softirq()
994           in the end of an hardirq.               898           in the end of an hardirq.
995           This spares a stack switch and impro    899           This spares a stack switch and improves cache usage on softirq
996           processing.                             900           processing.
997                                                   901 
998 config HAVE_SOFTIRQ_ON_OWN_STACK                  902 config HAVE_SOFTIRQ_ON_OWN_STACK
999         bool                                      903         bool
1000         help                                     904         help
1001           Architecture provides a function to    905           Architecture provides a function to run __do_softirq() on a
1002           separate stack.                        906           separate stack.
1003                                                  907 
1004 config SOFTIRQ_ON_OWN_STACK                   << 
1005         def_bool HAVE_SOFTIRQ_ON_OWN_STACK && << 
1006                                               << 
1007 config ALTERNATE_USER_ADDRESS_SPACE              908 config ALTERNATE_USER_ADDRESS_SPACE
1008         bool                                     909         bool
1009         help                                     910         help
1010           Architectures set this when the CPU    911           Architectures set this when the CPU uses separate address
1011           spaces for kernel and user space po    912           spaces for kernel and user space pointers. In this case, the
1012           access_ok() check on a __user point    913           access_ok() check on a __user pointer is skipped.
1013                                                  914 
1014 config PGTABLE_LEVELS                            915 config PGTABLE_LEVELS
1015         int                                      916         int
1016         default 2                                917         default 2
1017                                                  918 
1018 config ARCH_HAS_ELF_RANDOMIZE                    919 config ARCH_HAS_ELF_RANDOMIZE
1019         bool                                     920         bool
1020         help                                     921         help
1021           An architecture supports choosing r    922           An architecture supports choosing randomized locations for
1022           stack, mmap, brk, and ET_DYN. Defin    923           stack, mmap, brk, and ET_DYN. Defined functions:
1023           - arch_mmap_rnd()                      924           - arch_mmap_rnd()
1024           - arch_randomize_brk()                 925           - arch_randomize_brk()
1025                                                  926 
1026 config HAVE_ARCH_MMAP_RND_BITS                   927 config HAVE_ARCH_MMAP_RND_BITS
1027         bool                                     928         bool
1028         help                                     929         help
1029           An arch should select this symbol i    930           An arch should select this symbol if it supports setting a variable
1030           number of bits for use in establish    931           number of bits for use in establishing the base address for mmap
1031           allocations, has MMU enabled and pr    932           allocations, has MMU enabled and provides values for both:
1032           - ARCH_MMAP_RND_BITS_MIN               933           - ARCH_MMAP_RND_BITS_MIN
1033           - ARCH_MMAP_RND_BITS_MAX               934           - ARCH_MMAP_RND_BITS_MAX
1034                                                  935 
1035 config HAVE_EXIT_THREAD                          936 config HAVE_EXIT_THREAD
1036         bool                                     937         bool
1037         help                                     938         help
1038           An architecture implements exit_thr    939           An architecture implements exit_thread.
1039                                                  940 
1040 config ARCH_MMAP_RND_BITS_MIN                    941 config ARCH_MMAP_RND_BITS_MIN
1041         int                                      942         int
1042                                                  943 
1043 config ARCH_MMAP_RND_BITS_MAX                    944 config ARCH_MMAP_RND_BITS_MAX
1044         int                                      945         int
1045                                                  946 
1046 config ARCH_MMAP_RND_BITS_DEFAULT                947 config ARCH_MMAP_RND_BITS_DEFAULT
1047         int                                      948         int
1048                                                  949 
1049 config ARCH_MMAP_RND_BITS                        950 config ARCH_MMAP_RND_BITS
1050         int "Number of bits to use for ASLR o    951         int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051         range ARCH_MMAP_RND_BITS_MIN ARCH_MMA    952         range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052         default ARCH_MMAP_RND_BITS_DEFAULT if    953         default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053         default ARCH_MMAP_RND_BITS_MIN           954         default ARCH_MMAP_RND_BITS_MIN
1054         depends on HAVE_ARCH_MMAP_RND_BITS       955         depends on HAVE_ARCH_MMAP_RND_BITS
1055         help                                     956         help
1056           This value can be used to select th    957           This value can be used to select the number of bits to use to
1057           determine the random offset to the     958           determine the random offset to the base address of vma regions
1058           resulting from mmap allocations. Th    959           resulting from mmap allocations. This value will be bounded
1059           by the architecture's minimum and m    960           by the architecture's minimum and maximum supported values.
1060                                                  961 
1061           This value can be changed after boo    962           This value can be changed after boot using the
1062           /proc/sys/vm/mmap_rnd_bits tunable     963           /proc/sys/vm/mmap_rnd_bits tunable
1063                                                  964 
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS            965 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065         bool                                     966         bool
1066         help                                     967         help
1067           An arch should select this symbol i    968           An arch should select this symbol if it supports running applications
1068           in compatibility mode, supports set    969           in compatibility mode, supports setting a variable number of bits for
1069           use in establishing the base addres    970           use in establishing the base address for mmap allocations, has MMU
1070           enabled and provides values for bot    971           enabled and provides values for both:
1071           - ARCH_MMAP_RND_COMPAT_BITS_MIN        972           - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072           - ARCH_MMAP_RND_COMPAT_BITS_MAX        973           - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073                                                  974 
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN             975 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075         int                                      976         int
1076                                                  977 
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX             978 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078         int                                      979         int
1079                                                  980 
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT         981 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081         int                                      982         int
1082                                                  983 
1083 config ARCH_MMAP_RND_COMPAT_BITS                 984 config ARCH_MMAP_RND_COMPAT_BITS
1084         int "Number of bits to use for ASLR o    985         int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1085         range ARCH_MMAP_RND_COMPAT_BITS_MIN A    986         range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086         default ARCH_MMAP_RND_COMPAT_BITS_DEF    987         default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087         default ARCH_MMAP_RND_COMPAT_BITS_MIN    988         default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088         depends on HAVE_ARCH_MMAP_RND_COMPAT_    989         depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089         help                                     990         help
1090           This value can be used to select th    991           This value can be used to select the number of bits to use to
1091           determine the random offset to the     992           determine the random offset to the base address of vma regions
1092           resulting from mmap allocations for    993           resulting from mmap allocations for compatible applications This
1093           value will be bounded by the archit    994           value will be bounded by the architecture's minimum and maximum
1094           supported values.                      995           supported values.
1095                                                  996 
1096           This value can be changed after boo    997           This value can be changed after boot using the
1097           /proc/sys/vm/mmap_rnd_compat_bits t    998           /proc/sys/vm/mmap_rnd_compat_bits tunable
1098                                                  999 
1099 config HAVE_ARCH_COMPAT_MMAP_BASES               1000 config HAVE_ARCH_COMPAT_MMAP_BASES
1100         bool                                     1001         bool
1101         help                                     1002         help
1102           This allows 64bit applications to i    1003           This allows 64bit applications to invoke 32-bit mmap() syscall
1103           and vice-versa 32-bit applications     1004           and vice-versa 32-bit applications to call 64-bit mmap().
1104           Required for applications doing dif    1005           Required for applications doing different bitness syscalls.
1105                                                  1006 
1106 config HAVE_PAGE_SIZE_4KB                     << 
1107         bool                                  << 
1108                                               << 
1109 config HAVE_PAGE_SIZE_8KB                     << 
1110         bool                                  << 
1111                                               << 
1112 config HAVE_PAGE_SIZE_16KB                    << 
1113         bool                                  << 
1114                                               << 
1115 config HAVE_PAGE_SIZE_32KB                    << 
1116         bool                                  << 
1117                                               << 
1118 config HAVE_PAGE_SIZE_64KB                    << 
1119         bool                                  << 
1120                                               << 
1121 config HAVE_PAGE_SIZE_256KB                   << 
1122         bool                                  << 
1123                                               << 
1124 choice                                        << 
1125         prompt "MMU page size"                << 
1126                                               << 
1127 config PAGE_SIZE_4KB                          << 
1128         bool "4KiB pages"                     << 
1129         depends on HAVE_PAGE_SIZE_4KB         << 
1130         help                                  << 
1131           This option select the standard 4Ki << 
1132           available option on many architectu << 
1133           minimize memory consumption and is  << 
1134           memory systems.                     << 
1135           Some software that is written for x << 
1136           assumptions about the page size and << 
1137                                               << 
1138 config PAGE_SIZE_8KB                          << 
1139         bool "8KiB pages"                     << 
1140         depends on HAVE_PAGE_SIZE_8KB         << 
1141         help                                  << 
1142           This option is the only supported p << 
1143           processors, and can be slightly fas << 
1144                                               << 
1145 config PAGE_SIZE_16KB                         << 
1146         bool "16KiB pages"                    << 
1147         depends on HAVE_PAGE_SIZE_16KB        << 
1148         help                                  << 
1149           This option is usually a good compr << 
1150           consumption and performance for typ << 
1151           workloads, often saving a level of  << 
1152           to 4KB pages as well as reducing TL << 
1153           per-page operations in the kernel a << 
1154           page cache.                         << 
1155                                               << 
1156 config PAGE_SIZE_32KB                         << 
1157         bool "32KiB pages"                    << 
1158         depends on HAVE_PAGE_SIZE_32KB        << 
1159         help                                  << 
1160           Using 32KiB page size will result i << 
1161           kernel at the price of higher memor << 
1162           16KiB pages.  This option is availa << 
1163           Note that you will need a suitable  << 
1164           support this.                       << 
1165                                               << 
1166 config PAGE_SIZE_64KB                         << 
1167         bool "64KiB pages"                    << 
1168         depends on HAVE_PAGE_SIZE_64KB        << 
1169         help                                  << 
1170           Using 64KiB page size will result i << 
1171           kernel at the price of much higher  << 
1172           4KiB or 16KiB pages.                << 
1173           This is not suitable for general-pu << 
1174           better performance may be worth the << 
1175           supercomputing or database applicat << 
1176           large in-memory data rather than sm << 
1177                                               << 
1178 config PAGE_SIZE_256KB                        << 
1179         bool "256KiB pages"                   << 
1180         depends on HAVE_PAGE_SIZE_256KB       << 
1181         help                                  << 
1182           256KiB pages have little practical  << 
1183           memory usage.  The kernel will only << 
1184           that have been compiled with '-zmax << 
1185           (the default is 64KiB or 4KiB on mo << 
1186                                               << 
1187 endchoice                                     << 
1188                                               << 
1189 config PAGE_SIZE_LESS_THAN_64KB                  1007 config PAGE_SIZE_LESS_THAN_64KB
1190         def_bool y                               1008         def_bool y
                                                   >> 1009         depends on !ARM64_64K_PAGES
                                                   >> 1010         depends on !IA64_PAGE_SIZE_64KB
1191         depends on !PAGE_SIZE_64KB               1011         depends on !PAGE_SIZE_64KB
                                                   >> 1012         depends on !PARISC_PAGE_SIZE_64KB
                                                   >> 1013         depends on !PPC_64K_PAGES
1192         depends on PAGE_SIZE_LESS_THAN_256KB     1014         depends on PAGE_SIZE_LESS_THAN_256KB
1193                                                  1015 
1194 config PAGE_SIZE_LESS_THAN_256KB                 1016 config PAGE_SIZE_LESS_THAN_256KB
1195         def_bool y                               1017         def_bool y
                                                   >> 1018         depends on !PPC_256K_PAGES
1196         depends on !PAGE_SIZE_256KB              1019         depends on !PAGE_SIZE_256KB
1197                                                  1020 
1198 config PAGE_SHIFT                             << 
1199         int                                   << 
1200         default 12 if PAGE_SIZE_4KB           << 
1201         default 13 if PAGE_SIZE_8KB           << 
1202         default 14 if PAGE_SIZE_16KB          << 
1203         default 15 if PAGE_SIZE_32KB          << 
1204         default 16 if PAGE_SIZE_64KB          << 
1205         default 18 if PAGE_SIZE_256KB         << 
1206                                               << 
1207 # This allows to use a set of generic functio    1021 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche    1022 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit    1023 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout).                      1024 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p    1025 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK                               1026 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT     1027 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214         bool                                     1028         bool
1215         depends on MMU                           1029         depends on MMU
1216         select ARCH_HAS_ELF_RANDOMIZE            1030         select ARCH_HAS_ELF_RANDOMIZE
1217                                                  1031 
1218 config HAVE_OBJTOOL                           << 
1219         bool                                  << 
1220                                               << 
1221 config HAVE_JUMP_LABEL_HACK                   << 
1222         bool                                  << 
1223                                               << 
1224 config HAVE_NOINSTR_HACK                      << 
1225         bool                                  << 
1226                                               << 
1227 config HAVE_NOINSTR_VALIDATION                << 
1228         bool                                  << 
1229                                               << 
1230 config HAVE_UACCESS_VALIDATION                << 
1231         bool                                  << 
1232         select OBJTOOL                        << 
1233                                               << 
1234 config HAVE_STACK_VALIDATION                     1032 config HAVE_STACK_VALIDATION
1235         bool                                     1033         bool
1236         help                                     1034         help
1237           Architecture supports objtool compi !! 1035           Architecture supports the 'objtool check' host tool command, which
1238           validation.                         !! 1036           performs compile-time stack metadata validation.
1239                                                  1037 
1240 config HAVE_RELIABLE_STACKTRACE                  1038 config HAVE_RELIABLE_STACKTRACE
1241         bool                                     1039         bool
1242         help                                     1040         help
1243           Architecture has either save_stack_    1041           Architecture has either save_stack_trace_tsk_reliable() or
1244           arch_stack_walk_reliable() function    1042           arch_stack_walk_reliable() function which only returns a stack trace
1245           if it can guarantee the trace is re    1043           if it can guarantee the trace is reliable.
1246                                                  1044 
1247 config HAVE_ARCH_HASH                            1045 config HAVE_ARCH_HASH
1248         bool                                     1046         bool
1249         default n                                1047         default n
1250         help                                     1048         help
1251           If this is set, the architecture pr    1049           If this is set, the architecture provides an <asm/hash.h>
1252           file which provides platform-specif    1050           file which provides platform-specific implementations of some
1253           functions in <linux/hash.h> or fs/n    1051           functions in <linux/hash.h> or fs/namei.c.
1254                                                  1052 
1255 config HAVE_ARCH_NVRAM_OPS                       1053 config HAVE_ARCH_NVRAM_OPS
1256         bool                                     1054         bool
1257                                                  1055 
1258 config ISA_BUS_API                               1056 config ISA_BUS_API
1259         def_bool ISA                             1057         def_bool ISA
1260                                                  1058 
1261 #                                                1059 #
1262 # ABI hall of shame                              1060 # ABI hall of shame
1263 #                                                1061 #
1264 config CLONE_BACKWARDS                           1062 config CLONE_BACKWARDS
1265         bool                                     1063         bool
1266         help                                     1064         help
1267           Architecture has tls passed as the     1065           Architecture has tls passed as the 4th argument of clone(2),
1268           not the 5th one.                       1066           not the 5th one.
1269                                                  1067 
1270 config CLONE_BACKWARDS2                          1068 config CLONE_BACKWARDS2
1271         bool                                     1069         bool
1272         help                                     1070         help
1273           Architecture has the first two argu    1071           Architecture has the first two arguments of clone(2) swapped.
1274                                                  1072 
1275 config CLONE_BACKWARDS3                          1073 config CLONE_BACKWARDS3
1276         bool                                     1074         bool
1277         help                                     1075         help
1278           Architecture has tls passed as the     1076           Architecture has tls passed as the 3rd argument of clone(2),
1279           not the 5th one.                       1077           not the 5th one.
1280                                                  1078 
1281 config ODD_RT_SIGACTION                          1079 config ODD_RT_SIGACTION
1282         bool                                     1080         bool
1283         help                                     1081         help
1284           Architecture has unusual rt_sigacti    1082           Architecture has unusual rt_sigaction(2) arguments
1285                                                  1083 
1286 config OLD_SIGSUSPEND                            1084 config OLD_SIGSUSPEND
1287         bool                                     1085         bool
1288         help                                     1086         help
1289           Architecture has old sigsuspend(2)     1087           Architecture has old sigsuspend(2) syscall, of one-argument variety
1290                                                  1088 
1291 config OLD_SIGSUSPEND3                           1089 config OLD_SIGSUSPEND3
1292         bool                                     1090         bool
1293         help                                     1091         help
1294           Even weirder antique ABI - three-ar    1092           Even weirder antique ABI - three-argument sigsuspend(2)
1295                                                  1093 
1296 config OLD_SIGACTION                             1094 config OLD_SIGACTION
1297         bool                                     1095         bool
1298         help                                     1096         help
1299           Architecture has old sigaction(2) s    1097           Architecture has old sigaction(2) syscall.  Nope, not the same
1300           as OLD_SIGSUSPEND | OLD_SIGSUSPEND3    1098           as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301           but fairly different variant of sig    1099           but fairly different variant of sigaction(2), thanks to OSF/1
1302           compatibility...                       1100           compatibility...
1303                                                  1101 
1304 config COMPAT_OLD_SIGACTION                      1102 config COMPAT_OLD_SIGACTION
1305         bool                                     1103         bool
1306                                                  1104 
1307 config COMPAT_32BIT_TIME                         1105 config COMPAT_32BIT_TIME
1308         bool "Provide system calls for 32-bit    1106         bool "Provide system calls for 32-bit time_t"
1309         default !64BIT || COMPAT                 1107         default !64BIT || COMPAT
1310         help                                     1108         help
1311           This enables 32 bit time_t support     1109           This enables 32 bit time_t support in addition to 64 bit time_t support.
1312           This is relevant on all 32-bit arch    1110           This is relevant on all 32-bit architectures, and 64-bit architectures
1313           as part of compat syscall handling.    1111           as part of compat syscall handling.
1314                                                  1112 
1315 config ARCH_NO_PREEMPT                           1113 config ARCH_NO_PREEMPT
1316         bool                                     1114         bool
1317                                                  1115 
                                                   >> 1116 config ARCH_EPHEMERAL_INODES
                                                   >> 1117         def_bool n
                                                   >> 1118         help
                                                   >> 1119           An arch should select this symbol if it doesn't keep track of inode
                                                   >> 1120           instances on its own, but instead relies on something else (e.g. the
                                                   >> 1121           host kernel for an UML kernel).
                                                   >> 1122 
1318 config ARCH_SUPPORTS_RT                          1123 config ARCH_SUPPORTS_RT
1319         bool                                     1124         bool
1320                                                  1125 
1321 config CPU_NO_EFFICIENT_FFS                      1126 config CPU_NO_EFFICIENT_FFS
1322         def_bool n                               1127         def_bool n
1323                                                  1128 
1324 config HAVE_ARCH_VMAP_STACK                      1129 config HAVE_ARCH_VMAP_STACK
1325         def_bool n                               1130         def_bool n
1326         help                                     1131         help
1327           An arch should select this symbol i    1132           An arch should select this symbol if it can support kernel stacks
1328           in vmalloc space.  This means:         1133           in vmalloc space.  This means:
1329                                                  1134 
1330           - vmalloc space must be large enoug    1135           - vmalloc space must be large enough to hold many kernel stacks.
1331             This may rule out many 32-bit arc    1136             This may rule out many 32-bit architectures.
1332                                                  1137 
1333           - Stacks in vmalloc space need to w    1138           - Stacks in vmalloc space need to work reliably.  For example, if
1334             vmap page tables are created on d    1139             vmap page tables are created on demand, either this mechanism
1335             needs to work while the stack poi    1140             needs to work while the stack points to a virtual address with
1336             unpopulated page tables or arch c    1141             unpopulated page tables or arch code (switch_to() and switch_mm(),
1337             most likely) needs to ensure that    1142             most likely) needs to ensure that the stack's page table entries
1338             are populated before running on a    1143             are populated before running on a possibly unpopulated stack.
1339                                                  1144 
1340           - If the stack overflows into a gua    1145           - If the stack overflows into a guard page, something reasonable
1341             should happen.  The definition of    1146             should happen.  The definition of "reasonable" is flexible, but
1342             instantly rebooting without loggi    1147             instantly rebooting without logging anything would be unfriendly.
1343                                                  1148 
1344 config VMAP_STACK                                1149 config VMAP_STACK
1345         default y                                1150         default y
1346         bool "Use a virtually-mapped stack"      1151         bool "Use a virtually-mapped stack"
1347         depends on HAVE_ARCH_VMAP_STACK          1152         depends on HAVE_ARCH_VMAP_STACK
1348         depends on !KASAN || KASAN_HW_TAGS ||    1153         depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349         help                                     1154         help
1350           Enable this if you want the use vir    1155           Enable this if you want the use virtually-mapped kernel stacks
1351           with guard pages.  This causes kern    1156           with guard pages.  This causes kernel stack overflows to be
1352           caught immediately rather than caus    1157           caught immediately rather than causing difficult-to-diagnose
1353           corruption.                            1158           corruption.
1354                                                  1159 
1355           To use this with software KASAN mod    1160           To use this with software KASAN modes, the architecture must support
1356           backing virtual mappings with real     1161           backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357           must be enabled.                       1162           must be enabled.
1358                                                  1163 
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET         1164 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1360         def_bool n                               1165         def_bool n
1361         help                                     1166         help
1362           An arch should select this symbol i    1167           An arch should select this symbol if it can support kernel stack
1363           offset randomization with calls to     1168           offset randomization with calls to add_random_kstack_offset()
1364           during syscall entry and choose_ran    1169           during syscall entry and choose_random_kstack_offset() during
1365           syscall exit. Careful removal of -f    1170           syscall exit. Careful removal of -fstack-protector-strong and
1366           -fstack-protector should also be ap    1171           -fstack-protector should also be applied to the entry code and
1367           closely examined, as the artificial    1172           closely examined, as the artificial stack bump looks like an array
1368           to the compiler, so it will attempt    1173           to the compiler, so it will attempt to add canary checks regardless
1369           of the static branch state.            1174           of the static branch state.
1370                                                  1175 
1371 config RANDOMIZE_KSTACK_OFFSET                   1176 config RANDOMIZE_KSTACK_OFFSET
1372         bool "Support for randomizing kernel     1177         bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1373         default y                                1178         default y
1374         depends on HAVE_ARCH_RANDOMIZE_KSTACK    1179         depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1375         depends on INIT_STACK_NONE || !CC_IS_    1180         depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1376         help                                     1181         help
1377           The kernel stack offset can be rand    1182           The kernel stack offset can be randomized (after pt_regs) by
1378           roughly 5 bits of entropy, frustrat    1183           roughly 5 bits of entropy, frustrating memory corruption
1379           attacks that depend on stack addres    1184           attacks that depend on stack address determinism or
1380           cross-syscall address exposures.       1185           cross-syscall address exposures.
1381                                                  1186 
1382           The feature is controlled via the "    1187           The feature is controlled via the "randomize_kstack_offset=on/off"
1383           kernel boot param, and if turned of    1188           kernel boot param, and if turned off has zero overhead due to its use
1384           of static branches (see JUMP_LABEL)    1189           of static branches (see JUMP_LABEL).
1385                                                  1190 
1386           If unsure, say Y.                      1191           If unsure, say Y.
1387                                                  1192 
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT           1193 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1389         bool "Default state of kernel stack o    1194         bool "Default state of kernel stack offset randomization"
1390         depends on RANDOMIZE_KSTACK_OFFSET       1195         depends on RANDOMIZE_KSTACK_OFFSET
1391         help                                     1196         help
1392           Kernel stack offset randomization i    1197           Kernel stack offset randomization is controlled by kernel boot param
1393           "randomize_kstack_offset=on/off", a    1198           "randomize_kstack_offset=on/off", and this config chooses the default
1394           boot state.                            1199           boot state.
1395                                                  1200 
1396 config ARCH_OPTIONAL_KERNEL_RWX                  1201 config ARCH_OPTIONAL_KERNEL_RWX
1397         def_bool n                               1202         def_bool n
1398                                                  1203 
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT          1204 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400         def_bool n                               1205         def_bool n
1401                                                  1206 
1402 config ARCH_HAS_STRICT_KERNEL_RWX                1207 config ARCH_HAS_STRICT_KERNEL_RWX
1403         def_bool n                               1208         def_bool n
1404                                                  1209 
1405 config STRICT_KERNEL_RWX                         1210 config STRICT_KERNEL_RWX
1406         bool "Make kernel text and rodata rea    1211         bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407         depends on ARCH_HAS_STRICT_KERNEL_RWX    1212         depends on ARCH_HAS_STRICT_KERNEL_RWX
1408         default !ARCH_OPTIONAL_KERNEL_RWX ||     1213         default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409         help                                     1214         help
1410           If this is set, kernel text and rod    1215           If this is set, kernel text and rodata memory will be made read-only,
1411           and non-text memory will be made no    1216           and non-text memory will be made non-executable. This provides
1412           protection against certain security    1217           protection against certain security exploits (e.g. executing the heap
1413           or modifying text)                     1218           or modifying text)
1414                                                  1219 
1415           These features are considered stand    1220           These features are considered standard security practice these days.
1416           You should say Y here in almost all    1221           You should say Y here in almost all cases.
1417                                                  1222 
1418 config ARCH_HAS_STRICT_MODULE_RWX                1223 config ARCH_HAS_STRICT_MODULE_RWX
1419         def_bool n                               1224         def_bool n
1420                                                  1225 
1421 config STRICT_MODULE_RWX                         1226 config STRICT_MODULE_RWX
1422         bool "Set loadable kernel module data    1227         bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1423         depends on ARCH_HAS_STRICT_MODULE_RWX    1228         depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424         default !ARCH_OPTIONAL_KERNEL_RWX ||     1229         default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425         help                                     1230         help
1426           If this is set, module text and rod    1231           If this is set, module text and rodata memory will be made read-only,
1427           and non-text memory will be made no    1232           and non-text memory will be made non-executable. This provides
1428           protection against certain security    1233           protection against certain security exploits (e.g. writing to text)
1429                                                  1234 
1430 # select if the architecture provides an asm/    1235 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA                      1236 config ARCH_HAS_PHYS_TO_DMA
1432         bool                                     1237         bool
1433                                                  1238 
1434 config HAVE_ARCH_COMPILER_H                      1239 config HAVE_ARCH_COMPILER_H
1435         bool                                     1240         bool
1436         help                                     1241         help
1437           An architecture can select this if     1242           An architecture can select this if it provides an
1438           asm/compiler.h header that should b    1243           asm/compiler.h header that should be included after
1439           linux/compiler-*.h in order to over    1244           linux/compiler-*.h in order to override macro definitions that those
1440           headers generally provide.             1245           headers generally provide.
1441                                                  1246 
1442 config HAVE_ARCH_PREL32_RELOCATIONS              1247 config HAVE_ARCH_PREL32_RELOCATIONS
1443         bool                                     1248         bool
1444         help                                     1249         help
1445           May be selected by an architecture     1250           May be selected by an architecture if it supports place-relative
1446           32-bit relocations, both in the too    1251           32-bit relocations, both in the toolchain and in the module loader,
1447           in which case relative references c    1252           in which case relative references can be used in special sections
1448           for PCI fixup, initcalls etc which     1253           for PCI fixup, initcalls etc which are only half the size on 64 bit
1449           architectures, and don't require ru    1254           architectures, and don't require runtime relocation on relocatable
1450           kernels.                               1255           kernels.
1451                                                  1256 
1452 config ARCH_USE_MEMREMAP_PROT                    1257 config ARCH_USE_MEMREMAP_PROT
1453         bool                                     1258         bool
1454                                                  1259 
1455 config LOCK_EVENT_COUNTS                         1260 config LOCK_EVENT_COUNTS
1456         bool "Locking event counts collection    1261         bool "Locking event counts collection"
1457         depends on DEBUG_FS                      1262         depends on DEBUG_FS
1458         help                                     1263         help
1459           Enable light-weight counting of var    1264           Enable light-weight counting of various locking related events
1460           in the system with minimal performa    1265           in the system with minimal performance impact. This reduces
1461           the chance of application behavior     1266           the chance of application behavior change because of timing
1462           differences. The counts are reporte    1267           differences. The counts are reported via debugfs.
1463                                                  1268 
1464 # Select if the architecture has support for     1269 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR                             1270 config ARCH_HAS_RELR
1466         bool                                     1271         bool
1467                                                  1272 
1468 config RELR                                      1273 config RELR
1469         bool "Use RELR relocation packing"       1274         bool "Use RELR relocation packing"
1470         depends on ARCH_HAS_RELR && TOOLS_SUP    1275         depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471         default y                                1276         default y
1472         help                                     1277         help
1473           Store the kernel's dynamic relocati    1278           Store the kernel's dynamic relocations in the RELR relocation packing
1474           format. Requires a compatible linke    1279           format. Requires a compatible linker (LLD supports this feature), as
1475           well as compatible NM and OBJCOPY u    1280           well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476           are compatible).                       1281           are compatible).
1477                                                  1282 
1478 config ARCH_HAS_MEM_ENCRYPT                      1283 config ARCH_HAS_MEM_ENCRYPT
1479         bool                                     1284         bool
1480                                                  1285 
1481 config ARCH_HAS_CC_PLATFORM                      1286 config ARCH_HAS_CC_PLATFORM
1482         bool                                     1287         bool
1483                                                  1288 
1484 config HAVE_SPARSE_SYSCALL_NR                    1289 config HAVE_SPARSE_SYSCALL_NR
1485         bool                                  !! 1290        bool
1486         help                                  !! 1291        help
1487           An architecture should select this  !! 1292           An architecture should select this if its syscall numbering is sparse
1488           to save space. For example, MIPS ar    1293           to save space. For example, MIPS architecture has a syscall array with
1489           entries at 4000, 5000 and 6000 loca    1294           entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490           related optimizations for a given a    1295           related optimizations for a given architecture.
1491                                                  1296 
1492 config ARCH_HAS_VDSO_DATA                        1297 config ARCH_HAS_VDSO_DATA
1493         bool                                     1298         bool
1494                                                  1299 
1495 config HAVE_STATIC_CALL                          1300 config HAVE_STATIC_CALL
1496         bool                                     1301         bool
1497                                                  1302 
1498 config HAVE_STATIC_CALL_INLINE                   1303 config HAVE_STATIC_CALL_INLINE
1499         bool                                     1304         bool
1500         depends on HAVE_STATIC_CALL              1305         depends on HAVE_STATIC_CALL
1501         select OBJTOOL                        << 
1502                                                  1306 
1503 config HAVE_PREEMPT_DYNAMIC                      1307 config HAVE_PREEMPT_DYNAMIC
1504         bool                                     1308         bool
1505                                                  1309 
1506 config HAVE_PREEMPT_DYNAMIC_CALL                 1310 config HAVE_PREEMPT_DYNAMIC_CALL
1507         bool                                     1311         bool
1508         depends on HAVE_STATIC_CALL              1312         depends on HAVE_STATIC_CALL
1509         select HAVE_PREEMPT_DYNAMIC              1313         select HAVE_PREEMPT_DYNAMIC
1510         help                                     1314         help
1511           An architecture should select this  !! 1315            An architecture should select this if it can handle the preemption
1512           model being selected at boot time u !! 1316            model being selected at boot time using static calls.
1513                                                  1317 
1514           Where an architecture selects HAVE_ !! 1318            Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1515           preemption function will be patched !! 1319            preemption function will be patched directly.
1516                                                  1320 
1517           Where an architecture does not sele !! 1321            Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1518           call to a preemption function will  !! 1322            call to a preemption function will go through a trampoline, and the
1519           trampoline will be patched.         !! 1323            trampoline will be patched.
1520                                                  1324 
1521           It is strongly advised to support i !! 1325            It is strongly advised to support inline static call to avoid any
1522           overhead.                           !! 1326            overhead.
1523                                                  1327 
1524 config HAVE_PREEMPT_DYNAMIC_KEY                  1328 config HAVE_PREEMPT_DYNAMIC_KEY
1525         bool                                     1329         bool
1526         depends on HAVE_ARCH_JUMP_LABEL       !! 1330         depends on HAVE_ARCH_JUMP_LABEL && CC_HAS_ASM_GOTO
1527         select HAVE_PREEMPT_DYNAMIC              1331         select HAVE_PREEMPT_DYNAMIC
1528         help                                     1332         help
1529           An architecture should select this  !! 1333            An architecture should select this if it can handle the preemption
1530           model being selected at boot time u !! 1334            model being selected at boot time using static keys.
1531                                                  1335 
1532           Each preemption function will be gi !! 1336            Each preemption function will be given an early return based on a
1533           static key. This should have slight !! 1337            static key. This should have slightly lower overhead than non-inline
1534           static calls, as this effectively i !! 1338            static calls, as this effectively inlines each trampoline into the
1535           start of its callee. This may avoid !! 1339            start of its callee. This may avoid redundant work, and may
1536           integrate better with CFI schemes.  !! 1340            integrate better with CFI schemes.
1537                                                  1341 
1538           This will have greater overhead tha !! 1342            This will have greater overhead than using inline static calls as
1539           the call to the preemption function !! 1343            the call to the preemption function cannot be entirely elided.
1540                                                  1344 
1541 config ARCH_WANT_LD_ORPHAN_WARN                  1345 config ARCH_WANT_LD_ORPHAN_WARN
1542         bool                                     1346         bool
1543         help                                     1347         help
1544           An arch should select this symbol o    1348           An arch should select this symbol once all linker sections are explicitly
1545           included, size-asserted, or discard    1349           included, size-asserted, or discarded in the linker scripts. This is
1546           important because we never want exp    1350           important because we never want expected sections to be placed heuristically
1547           by the linker, since the locations     1351           by the linker, since the locations of such sections can change between linker
1548           versions.                              1352           versions.
1549                                                  1353 
1550 config HAVE_ARCH_PFN_VALID                       1354 config HAVE_ARCH_PFN_VALID
1551         bool                                     1355         bool
1552                                                  1356 
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC             1357 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554         bool                                     1358         bool
1555                                                  1359 
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK            1360 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1557         bool                                     1361         bool
1558                                                  1362 
1559 config ARCH_SPLIT_ARG64                          1363 config ARCH_SPLIT_ARG64
1560         bool                                     1364         bool
1561         help                                     1365         help
1562           If a 32-bit architecture requires 6 !! 1366            If a 32-bit architecture requires 64-bit arguments to be split into
1563           pairs of 32-bit arguments, select t !! 1367            pairs of 32-bit arguments, select this option.
1564                                                  1368 
1565 config ARCH_HAS_ELFCORE_COMPAT                   1369 config ARCH_HAS_ELFCORE_COMPAT
1566         bool                                     1370         bool
1567                                                  1371 
1568 config ARCH_HAS_PARANOID_L1D_FLUSH               1372 config ARCH_HAS_PARANOID_L1D_FLUSH
1569         bool                                     1373         bool
1570                                                  1374 
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS            << 
1572         bool                                  << 
1573                                               << 
1574 config DYNAMIC_SIGFRAME                          1375 config DYNAMIC_SIGFRAME
1575         bool                                     1376         bool
1576                                                  1377 
1577 # Select, if arch has a named attribute group    1378 # Select, if arch has a named attribute group bound to NUMA device nodes.
1578 config HAVE_ARCH_NODE_DEV_GROUP                  1379 config HAVE_ARCH_NODE_DEV_GROUP
1579         bool                                     1380         bool
1580                                                  1381 
1581 config ARCH_HAS_HW_PTE_YOUNG                  << 
1582         bool                                  << 
1583         help                                  << 
1584           Architectures that select this opti << 
1585           accessed bit in PTE entries when us << 
1586           translations. Architectures that re << 
1587           this option and override arch_has_h << 
1588                                               << 
1589 config ARCH_HAS_NONLEAF_PMD_YOUNG             << 
1590         bool                                  << 
1591         help                                  << 
1592           Architectures that select this opti << 
1593           accessed bit in non-leaf PMD entrie << 
1594           address translations. Page table wa << 
1595           may use this capability to reduce t << 
1596                                               << 
1597 config ARCH_HAS_KERNEL_FPU_SUPPORT            << 
1598         bool                                  << 
1599         help                                  << 
1600           Architectures that select this opti << 
1601           the kernel, as described in Documen << 
1602                                               << 
1603 source "kernel/gcov/Kconfig"                     1382 source "kernel/gcov/Kconfig"
1604                                                  1383 
1605 source "scripts/gcc-plugins/Kconfig"             1384 source "scripts/gcc-plugins/Kconfig"
1606                                               << 
1607 config FUNCTION_ALIGNMENT_4B                  << 
1608         bool                                  << 
1609                                               << 
1610 config FUNCTION_ALIGNMENT_8B                  << 
1611         bool                                  << 
1612                                               << 
1613 config FUNCTION_ALIGNMENT_16B                 << 
1614         bool                                  << 
1615                                               << 
1616 config FUNCTION_ALIGNMENT_32B                 << 
1617         bool                                  << 
1618                                               << 
1619 config FUNCTION_ALIGNMENT_64B                 << 
1620         bool                                  << 
1621                                               << 
1622 config FUNCTION_ALIGNMENT                     << 
1623         int                                   << 
1624         default 64 if FUNCTION_ALIGNMENT_64B  << 
1625         default 32 if FUNCTION_ALIGNMENT_32B  << 
1626         default 16 if FUNCTION_ALIGNMENT_16B  << 
1627         default 8 if FUNCTION_ALIGNMENT_8B    << 
1628         default 4 if FUNCTION_ALIGNMENT_4B    << 
1629         default 0                             << 
1630                                               << 
1631 config CC_HAS_MIN_FUNCTION_ALIGNMENT          << 
1632         # Detect availability of the GCC opti << 
1633         # guarantees minimal alignment for al << 
1634         # -falign-functions which the compile << 
1635         def_bool $(cc-option, -fmin-function- << 
1636                                               << 
1637 config CC_HAS_SANE_FUNCTION_ALIGNMENT         << 
1638         # Set if the guaranteed alignment wit << 
1639         # available or extra care is required << 
1640         # strict alignment always, even with  << 
1641         def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN << 
1642                                               << 
1643 config ARCH_NEED_CMPXCHG_1_EMU                << 
1644         bool                                  << 
1645                                                  1385 
1646 endmenu                                          1386 endmenu
                                                      

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