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 15 bool 24 help << 25 Select if the architecture can check << 26 granularity (e.g. arm64 MTE). The pr << 27 must be implemented. << 28 16 29 config HOTPLUG_SMT !! 17 config KEXEC_CORE >> 18 select CRASH_CORE 30 bool 19 bool 31 20 32 config SMT_NUM_THREADS_DYNAMIC !! 21 config KEXEC_ELF 33 bool 22 bool 34 23 35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HAVE_IMA_KEXEC 36 config HOTPLUG_CORE_SYNC << 37 bool 25 bool 38 26 39 # Basic CPU dead synchronization selected by a !! 27 config SET_FS 40 config HOTPLUG_CORE_SYNC_DEAD << 41 bool 28 bool 42 select HOTPLUG_CORE_SYNC << 43 29 44 # Full CPU synchronization with alive state se !! 30 config HOTPLUG_SMT 45 config HOTPLUG_CORE_SYNC_FULL << 46 bool 31 bool 47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL << 48 select HOTPLUG_CORE_SYNC << 49 32 50 config HOTPLUG_SPLIT_STARTUP !! 33 config GENERIC_ENTRY 51 bool !! 34 bool 52 select HOTPLUG_CORE_SYNC_FULL << 53 35 54 config HOTPLUG_PARALLEL !! 36 config OPROFILE 55 bool !! 37 tristate "OProfile system profiling" 56 select HOTPLUG_SPLIT_STARTUP !! 38 depends on PROFILING >> 39 depends on HAVE_OPROFILE >> 40 select RING_BUFFER >> 41 select RING_BUFFER_ALLOW_SWAP >> 42 help >> 43 OProfile is a profiling system capable of profiling the >> 44 whole system, include the kernel, kernel modules, libraries, >> 45 and applications. 57 46 58 config GENERIC_ENTRY !! 47 If unsure, say N. >> 48 >> 49 config OPROFILE_EVENT_MULTIPLEX >> 50 bool "OProfile multiplexing support (EXPERIMENTAL)" >> 51 default n >> 52 depends on OPROFILE && X86 >> 53 help >> 54 The number of hardware counters is limited. The multiplexing >> 55 feature enables OProfile to gather more events than counters >> 56 are provided by the hardware. This is realized by switching >> 57 between events at a user specified time interval. >> 58 >> 59 If unsure, say N. >> 60 >> 61 config HAVE_OPROFILE 59 bool 62 bool 60 63 >> 64 config OPROFILE_NMI_TIMER >> 65 def_bool y >> 66 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 >> 67 61 config KPROBES 68 config KPROBES 62 bool "Kprobes" 69 bool "Kprobes" >> 70 depends on MODULES 63 depends on HAVE_KPROBES 71 depends on HAVE_KPROBES 64 select KALLSYMS 72 select KALLSYMS 65 select EXECMEM << 66 select NEED_TASKS_RCU << 67 help 73 help 68 Kprobes allows you to trap at almost 74 Kprobes allows you to trap at almost any kernel address and 69 execute a callback function. regist 75 execute a callback function. register_kprobe() establishes 70 a probepoint and specifies the callb 76 a probepoint and specifies the callback. Kprobes is useful 71 for kernel debugging, non-intrusive 77 for kernel debugging, non-intrusive instrumentation and testing. 72 If in doubt, say "N". 78 If in doubt, say "N". 73 79 74 config JUMP_LABEL 80 config JUMP_LABEL 75 bool "Optimize very unlikely/likely br 81 bool "Optimize very unlikely/likely branches" 76 depends on HAVE_ARCH_JUMP_LABEL 82 depends on HAVE_ARCH_JUMP_LABEL 77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 83 depends on CC_HAS_ASM_GOTO 78 help 84 help 79 This option enables a transparent br !! 85 This option enables a transparent branch optimization that 80 makes certain almost-always-true or !! 86 makes certain almost-always-true or almost-always-false branch 81 conditions even cheaper to execute w !! 87 conditions even cheaper to execute within the kernel. 82 !! 88 83 Certain performance-sensitive kernel !! 89 Certain performance-sensitive kernel code, such as trace points, 84 scheduler functionality, networking !! 90 scheduler functionality, networking code and KVM have such 85 branches and include support for thi !! 91 branches and include support for this optimization technique. 86 !! 92 87 If it is detected that the compiler !! 93 If it is detected that the compiler has support for "asm goto", 88 the kernel will compile such branche !! 94 the kernel will compile such branches with just a nop 89 instruction. When the condition flag !! 95 instruction. When the condition flag is toggled to true, the 90 nop will be converted to a jump inst !! 96 nop will be converted to a jump instruction to execute the 91 conditional block of instructions. !! 97 conditional block of instructions. 92 !! 98 93 This technique lowers overhead and s !! 99 This technique lowers overhead and stress on the branch prediction 94 of the processor and generally makes !! 100 of the processor and generally makes the kernel faster. The update 95 of the condition is slower, but thos !! 101 of the condition is slower, but those are always very rare. 96 102 97 ( On 32-bit x86, the necessary optio !! 103 ( On 32-bit x86, the necessary options added to the compiler 98 flags may increase the size of the !! 104 flags may increase the size of the kernel slightly. ) 99 105 100 config STATIC_KEYS_SELFTEST 106 config STATIC_KEYS_SELFTEST 101 bool "Static key selftest" 107 bool "Static key selftest" 102 depends on JUMP_LABEL 108 depends on JUMP_LABEL 103 help 109 help 104 Boot time self-test of the branch pa 110 Boot time self-test of the branch patching code. 105 111 106 config STATIC_CALL_SELFTEST 112 config STATIC_CALL_SELFTEST 107 bool "Static call selftest" 113 bool "Static call selftest" 108 depends on HAVE_STATIC_CALL 114 depends on HAVE_STATIC_CALL 109 help 115 help 110 Boot time self-test of the call patc 116 Boot time self-test of the call patching code. 111 117 112 config OPTPROBES 118 config OPTPROBES 113 def_bool y 119 def_bool y 114 depends on KPROBES && HAVE_OPTPROBES 120 depends on KPROBES && HAVE_OPTPROBES 115 select NEED_TASKS_RCU !! 121 select TASKS_RCU if PREEMPTION 116 122 117 config KPROBES_ON_FTRACE 123 config KPROBES_ON_FTRACE 118 def_bool y 124 def_bool y 119 depends on KPROBES && HAVE_KPROBES_ON_ 125 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 120 depends on DYNAMIC_FTRACE_WITH_REGS 126 depends on DYNAMIC_FTRACE_WITH_REGS 121 help 127 help 122 If function tracer is enabled and th !! 128 If function tracer is enabled and the arch supports full 123 passing of pt_regs to function traci !! 129 passing of pt_regs to function tracing, then kprobes can 124 optimize on top of function tracing. !! 130 optimize on top of function tracing. 125 131 126 config UPROBES 132 config UPROBES 127 def_bool n 133 def_bool n 128 depends on ARCH_SUPPORTS_UPROBES 134 depends on ARCH_SUPPORTS_UPROBES 129 help 135 help 130 Uprobes is the user-space counterpar 136 Uprobes is the user-space counterpart to kprobes: they 131 enable instrumentation applications 137 enable instrumentation applications (such as 'perf probe') 132 to establish unintrusive probes in u 138 to establish unintrusive probes in user-space binaries and 133 libraries, by executing handler func 139 libraries, by executing handler functions when the probes 134 are hit by user-space applications. 140 are hit by user-space applications. 135 141 136 ( These probes come in the form of s 142 ( These probes come in the form of single-byte breakpoints, 137 managed by the kernel and kept tra 143 managed by the kernel and kept transparent to the probed 138 application. ) 144 application. ) 139 145 140 config HAVE_64BIT_ALIGNED_ACCESS 146 config HAVE_64BIT_ALIGNED_ACCESS 141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 147 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 142 help 148 help 143 Some architectures require 64 bit ac 149 Some architectures require 64 bit accesses to be 64 bit 144 aligned, which also requires structs 150 aligned, which also requires structs containing 64 bit values 145 to be 64 bit aligned too. This inclu 151 to be 64 bit aligned too. This includes some 32 bit 146 architectures which can do 64 bit ac 152 architectures which can do 64 bit accesses, as well as 64 bit 147 architectures without unaligned acce 153 architectures without unaligned access. 148 154 149 This symbol should be selected by an 155 This symbol should be selected by an architecture if 64 bit 150 accesses are required to be 64 bit a 156 accesses are required to be 64 bit aligned in this way even 151 though it is not a 64 bit architectu 157 though it is not a 64 bit architecture. 152 158 153 See Documentation/core-api/unaligned !! 159 See Documentation/unaligned-memory-access.txt for more 154 more information on the topic of una !! 160 information on the topic of unaligned memory accesses. 155 161 156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 162 config HAVE_EFFICIENT_UNALIGNED_ACCESS 157 bool 163 bool 158 help 164 help 159 Some architectures are unable to per 165 Some architectures are unable to perform unaligned accesses 160 without the use of get_unaligned/put 166 without the use of get_unaligned/put_unaligned. Others are 161 unable to perform such accesses effi 167 unable to perform such accesses efficiently (e.g. trap on 162 unaligned access and require fixing 168 unaligned access and require fixing it up in the exception 163 handler.) 169 handler.) 164 170 165 This symbol should be selected by an 171 This symbol should be selected by an architecture if it can 166 perform unaligned accesses efficient 172 perform unaligned accesses efficiently to allow different 167 code paths to be selected for these 173 code paths to be selected for these cases. Some network 168 drivers, for example, could opt to n 174 drivers, for example, could opt to not fix up alignment 169 problems with received packets if do 175 problems with received packets if doing so would not help 170 much. 176 much. 171 177 172 See Documentation/core-api/unaligned 178 See Documentation/core-api/unaligned-memory-access.rst for more 173 information on the topic of unaligne 179 information on the topic of unaligned memory accesses. 174 180 175 config ARCH_USE_BUILTIN_BSWAP 181 config ARCH_USE_BUILTIN_BSWAP 176 bool 182 bool 177 help 183 help 178 Modern versions of GCC (since 4.4) h !! 184 Modern versions of GCC (since 4.4) have builtin functions 179 for handling byte-swapping. Using th !! 185 for handling byte-swapping. Using these, instead of the old 180 inline assembler that the architectu !! 186 inline assembler that the architecture code provides in the 181 __arch_bswapXX() macros, allows the !! 187 __arch_bswapXX() macros, allows the compiler to see what's 182 happening and offers more opportunit !! 188 happening and offers more opportunity for optimisation. In 183 particular, the compiler will be abl !! 189 particular, the compiler will be able to combine the byteswap 184 with a nearby load or store and use !! 190 with a nearby load or store and use load-and-swap or 185 store-and-swap instructions if the a !! 191 store-and-swap instructions if the architecture has them. It 186 should almost *never* result in code !! 192 should almost *never* result in code which is worse than the 187 hand-coded assembler in <asm/swab.h> !! 193 hand-coded assembler in <asm/swab.h>. But just in case it 188 does, the use of the builtins is opt !! 194 does, the use of the builtins is optional. 189 !! 195 190 Any architecture with load-and-swap !! 196 Any architecture with load-and-swap or store-and-swap 191 instructions should set this. And it !! 197 instructions should set this. And it shouldn't hurt to set it 192 on architectures that don't have suc !! 198 on architectures that don't have such instructions. 193 199 194 config KRETPROBES 200 config KRETPROBES 195 def_bool y 201 def_bool y 196 depends on KPROBES && (HAVE_KRETPROBES !! 202 depends on KPROBES && HAVE_KRETPROBES 197 << 198 config KRETPROBE_ON_RETHOOK << 199 def_bool y << 200 depends on HAVE_RETHOOK << 201 depends on KRETPROBES << 202 select RETHOOK << 203 203 204 config USER_RETURN_NOTIFIER 204 config USER_RETURN_NOTIFIER 205 bool 205 bool 206 depends on HAVE_USER_RETURN_NOTIFIER 206 depends on HAVE_USER_RETURN_NOTIFIER 207 help 207 help 208 Provide a kernel-internal notificati 208 Provide a kernel-internal notification when a cpu is about to 209 switch to user mode. 209 switch to user mode. 210 210 211 config HAVE_IOREMAP_PROT 211 config HAVE_IOREMAP_PROT 212 bool 212 bool 213 213 214 config HAVE_KPROBES 214 config HAVE_KPROBES 215 bool 215 bool 216 216 217 config HAVE_KRETPROBES 217 config HAVE_KRETPROBES 218 bool 218 bool 219 219 220 config HAVE_OPTPROBES 220 config HAVE_OPTPROBES 221 bool 221 bool 222 222 223 config HAVE_KPROBES_ON_FTRACE 223 config HAVE_KPROBES_ON_FTRACE 224 bool 224 bool 225 225 226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE << 227 bool << 228 help << 229 Since kretprobes modifies return add << 230 stacktrace may see the kretprobe tra << 231 of correct one. If the architecture << 232 unwinder can adjust such entries, se << 233 << 234 config HAVE_FUNCTION_ERROR_INJECTION 226 config HAVE_FUNCTION_ERROR_INJECTION 235 bool 227 bool 236 228 237 config HAVE_NMI 229 config HAVE_NMI 238 bool 230 bool 239 231 240 config HAVE_FUNCTION_DESCRIPTORS << 241 bool << 242 << 243 config TRACE_IRQFLAGS_SUPPORT << 244 bool << 245 << 246 config TRACE_IRQFLAGS_NMI_SUPPORT << 247 bool << 248 << 249 # 232 # 250 # An arch should select this if it provides al 233 # An arch should select this if it provides all these things: 251 # 234 # 252 # task_pt_regs() in asm/process 235 # task_pt_regs() in asm/processor.h or asm/ptrace.h 253 # arch_has_single_step() if there is ha 236 # arch_has_single_step() if there is hardware single-step support 254 # arch_has_block_step() if there is ha 237 # arch_has_block_step() if there is hardware block-step support 255 # asm/syscall.h supplying asm- 238 # asm/syscall.h supplying asm-generic/syscall.h interface 256 # linux/regset.h user_regset in 239 # linux/regset.h user_regset interfaces 257 # CORE_DUMP_USE_REGSET #define'd in l 240 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h 258 # TIF_SYSCALL_TRACE calls ptrace_r !! 241 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 259 # TIF_NOTIFY_RESUME calls resume_u !! 242 # TIF_NOTIFY_RESUME calls tracehook_notify_resume() >> 243 # signal delivery calls tracehook_signal_handler() 260 # 244 # 261 config HAVE_ARCH_TRACEHOOK 245 config HAVE_ARCH_TRACEHOOK 262 bool 246 bool 263 247 264 config HAVE_DMA_CONTIGUOUS 248 config HAVE_DMA_CONTIGUOUS 265 bool 249 bool 266 250 267 config GENERIC_SMP_IDLE_THREAD 251 config GENERIC_SMP_IDLE_THREAD 268 bool 252 bool 269 253 270 config GENERIC_IDLE_POLL_SETUP 254 config GENERIC_IDLE_POLL_SETUP 271 bool 255 bool 272 256 273 config ARCH_HAS_FORTIFY_SOURCE 257 config ARCH_HAS_FORTIFY_SOURCE 274 bool 258 bool 275 help 259 help 276 An architecture should select this w 260 An architecture should select this when it can successfully 277 build and run with CONFIG_FORTIFY_SO 261 build and run with CONFIG_FORTIFY_SOURCE. 278 262 279 # 263 # 280 # Select if the arch provides a historic keepi 264 # Select if the arch provides a historic keepinit alias for the retain_initrd 281 # command line option 265 # command line option 282 # 266 # 283 config ARCH_HAS_KEEPINITRD 267 config ARCH_HAS_KEEPINITRD 284 bool 268 bool 285 269 286 # Select if arch has all set_memory_ro/rw/x/nx 270 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 287 config ARCH_HAS_SET_MEMORY 271 config ARCH_HAS_SET_MEMORY 288 bool 272 bool 289 273 290 # Select if arch has all set_direct_map_invali 274 # Select if arch has all set_direct_map_invalid/default() functions 291 config ARCH_HAS_SET_DIRECT_MAP 275 config ARCH_HAS_SET_DIRECT_MAP 292 bool 276 bool 293 277 294 # 278 # 295 # Select if the architecture provides the arch 279 # Select if the architecture provides the arch_dma_set_uncached symbol to 296 # either provide an uncached segment alias for 280 # either provide an uncached segment alias for a DMA allocation, or 297 # to remap the page tables in place. 281 # to remap the page tables in place. 298 # 282 # 299 config ARCH_HAS_DMA_SET_UNCACHED 283 config ARCH_HAS_DMA_SET_UNCACHED 300 bool 284 bool 301 285 302 # 286 # 303 # Select if the architectures provides the arc 287 # Select if the architectures provides the arch_dma_clear_uncached symbol 304 # to undo an in-place page table remap for unc 288 # to undo an in-place page table remap for uncached access. 305 # 289 # 306 config ARCH_HAS_DMA_CLEAR_UNCACHED 290 config ARCH_HAS_DMA_CLEAR_UNCACHED 307 bool 291 bool 308 292 309 config ARCH_HAS_CPU_FINALIZE_INIT !! 293 # Select if arch init_task must go in the __init_task_data section >> 294 config ARCH_TASK_STRUCT_ON_STACK 310 bool 295 bool 311 296 312 # The architecture has a per-task state that i !! 297 # Select if arch has its private alloc_task_struct() function 313 config ARCH_HAS_CPU_PASID !! 298 config ARCH_TASK_STRUCT_ALLOCATOR 314 bool 299 bool 315 select IOMMU_MM_DATA << 316 300 317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 301 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 318 bool 302 bool >> 303 depends on !ARCH_TASK_STRUCT_ALLOCATOR 319 help 304 help 320 An architecture should select this t 305 An architecture should select this to provide hardened usercopy 321 knowledge about what region of the t 306 knowledge about what region of the thread_struct should be 322 whitelisted for copying to userspace 307 whitelisted for copying to userspace. Normally this is only the 323 FPU registers. Specifically, arch_th 308 FPU registers. Specifically, arch_thread_struct_whitelist() 324 should be implemented. Without this, 309 should be implemented. Without this, the entire thread_struct 325 field in task_struct will be left wh 310 field in task_struct will be left whitelisted. 326 311 327 # Select if arch wants to size task_struct dyn !! 312 # Select if arch has its private alloc_thread_stack() function 328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 313 config ARCH_THREAD_STACK_ALLOCATOR 329 bool 314 bool 330 315 331 config ARCH_WANTS_NO_INSTR !! 316 # Select if arch wants to size task_struct dynamically via arch_task_struct_size: >> 317 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 332 bool 318 bool 333 help << 334 An architecture should select this i << 335 functions to denote that the toolcha << 336 functions and is required for correc << 337 319 338 config ARCH_32BIT_OFF_T 320 config ARCH_32BIT_OFF_T 339 bool 321 bool 340 depends on !64BIT 322 depends on !64BIT 341 help 323 help 342 All new 32-bit architectures should 324 All new 32-bit architectures should have 64-bit off_t type on 343 userspace side which corresponds to 325 userspace side which corresponds to the loff_t kernel type. This 344 is the requirement for modern ABIs. 326 is the requirement for modern ABIs. Some existing architectures 345 still support 32-bit off_t. This opt 327 still support 32-bit off_t. This option is enabled for all such 346 architectures explicitly. 328 architectures explicitly. 347 329 348 # Selected by 64 bit architectures which have << 349 config ARCH_32BIT_USTAT_F_TINODE << 350 bool << 351 << 352 config HAVE_ASM_MODVERSIONS 330 config HAVE_ASM_MODVERSIONS 353 bool 331 bool 354 help 332 help 355 This symbol should be selected by an 333 This symbol should be selected by an architecture if it provides 356 <asm/asm-prototypes.h> to support th 334 <asm/asm-prototypes.h> to support the module versioning for symbols 357 exported from assembly code. 335 exported from assembly code. 358 336 359 config HAVE_REGS_AND_STACK_ACCESS_API 337 config HAVE_REGS_AND_STACK_ACCESS_API 360 bool 338 bool 361 help 339 help 362 This symbol should be selected by an 340 This symbol should be selected by an architecture if it supports 363 the API needed to access registers a 341 the API needed to access registers and stack entries from pt_regs, 364 declared in asm/ptrace.h 342 declared in asm/ptrace.h 365 For example the kprobes-based event 343 For example the kprobes-based event tracer needs this API. 366 344 367 config HAVE_RSEQ 345 config HAVE_RSEQ 368 bool 346 bool 369 depends on HAVE_REGS_AND_STACK_ACCESS_ 347 depends on HAVE_REGS_AND_STACK_ACCESS_API 370 help 348 help 371 This symbol should be selected by an 349 This symbol should be selected by an architecture if it 372 supports an implementation of restar 350 supports an implementation of restartable sequences. 373 351 374 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 352 config HAVE_FUNCTION_ARG_ACCESS_API 381 bool 353 bool 382 help 354 help 383 This symbol should be selected by an 355 This symbol should be selected by an architecture if it supports 384 the API needed to access function ar 356 the API needed to access function arguments from pt_regs, 385 declared in asm/ptrace.h 357 declared in asm/ptrace.h 386 358 387 config HAVE_HW_BREAKPOINT 359 config HAVE_HW_BREAKPOINT 388 bool 360 bool 389 depends on PERF_EVENTS 361 depends on PERF_EVENTS 390 362 391 config HAVE_MIXED_BREAKPOINTS_REGS 363 config HAVE_MIXED_BREAKPOINTS_REGS 392 bool 364 bool 393 depends on HAVE_HW_BREAKPOINT 365 depends on HAVE_HW_BREAKPOINT 394 help 366 help 395 Depending on the arch implementation 367 Depending on the arch implementation of hardware breakpoints, 396 some of them have separate registers 368 some of them have separate registers for data and instruction 397 breakpoints addresses, others have m 369 breakpoints addresses, others have mixed registers to store 398 them but define the access type in a 370 them but define the access type in a control register. 399 Select this option if your arch impl 371 Select this option if your arch implements breakpoints under the 400 latter fashion. 372 latter fashion. 401 373 402 config HAVE_USER_RETURN_NOTIFIER 374 config HAVE_USER_RETURN_NOTIFIER 403 bool 375 bool 404 376 405 config HAVE_PERF_EVENTS_NMI 377 config HAVE_PERF_EVENTS_NMI 406 bool 378 bool 407 help 379 help 408 System hardware can generate an NMI 380 System hardware can generate an NMI using the perf event 409 subsystem. Also has support for cal 381 subsystem. Also has support for calculating CPU cycle events 410 to determine how many clock cycles i 382 to determine how many clock cycles in a given period. 411 383 412 config HAVE_HARDLOCKUP_DETECTOR_PERF 384 config HAVE_HARDLOCKUP_DETECTOR_PERF 413 bool 385 bool 414 depends on HAVE_PERF_EVENTS_NMI 386 depends on HAVE_PERF_EVENTS_NMI 415 help 387 help 416 The arch chooses to use the generic 388 The arch chooses to use the generic perf-NMI-based hardlockup 417 detector. Must define HAVE_PERF_EVEN 389 detector. Must define HAVE_PERF_EVENTS_NMI. 418 390 419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 391 config HAVE_NMI_WATCHDOG >> 392 depends on HAVE_NMI 420 bool 393 bool 421 help 394 help 422 The arch provides its own hardlockup !! 395 The arch provides a low level NMI watchdog. It provides 423 of the generic ones. !! 396 asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 424 397 425 It uses the same command line parame !! 398 config HAVE_HARDLOCKUP_DETECTOR_ARCH 426 as the generic hardlockup detectors. !! 399 bool >> 400 select HAVE_NMI_WATCHDOG >> 401 help >> 402 The arch chooses to provide its own hardlockup detector, which is >> 403 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config >> 404 interfaces and parameters provided by hardlockup detector subsystem. 427 405 428 config HAVE_PERF_REGS 406 config HAVE_PERF_REGS 429 bool 407 bool 430 help 408 help 431 Support selective register dumps for 409 Support selective register dumps for perf events. This includes 432 bit-mapping of each registers and a 410 bit-mapping of each registers and a unique architecture id. 433 411 434 config HAVE_PERF_USER_STACK_DUMP 412 config HAVE_PERF_USER_STACK_DUMP 435 bool 413 bool 436 help 414 help 437 Support user stack dumps for perf ev 415 Support user stack dumps for perf event samples. This needs 438 access to the user stack pointer whi 416 access to the user stack pointer which is not unified across 439 architectures. 417 architectures. 440 418 441 config HAVE_ARCH_JUMP_LABEL 419 config HAVE_ARCH_JUMP_LABEL 442 bool 420 bool 443 421 444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 422 config HAVE_ARCH_JUMP_LABEL_RELATIVE 445 bool 423 bool 446 424 447 config MMU_GATHER_TABLE_FREE 425 config MMU_GATHER_TABLE_FREE 448 bool 426 bool 449 427 450 config MMU_GATHER_RCU_TABLE_FREE 428 config MMU_GATHER_RCU_TABLE_FREE 451 bool 429 bool 452 select MMU_GATHER_TABLE_FREE 430 select MMU_GATHER_TABLE_FREE 453 431 454 config MMU_GATHER_PAGE_SIZE 432 config MMU_GATHER_PAGE_SIZE 455 bool 433 bool 456 434 457 config MMU_GATHER_NO_RANGE 435 config MMU_GATHER_NO_RANGE 458 bool 436 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 << 466 437 467 config MMU_GATHER_NO_GATHER 438 config MMU_GATHER_NO_GATHER 468 bool 439 bool 469 depends on MMU_GATHER_TABLE_FREE 440 depends on MMU_GATHER_TABLE_FREE 470 441 471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 442 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 472 bool 443 bool 473 help 444 help 474 Temporary select until all architect 445 Temporary select until all architectures can be converted to have 475 irqs disabled over activate_mm. Arch 446 irqs disabled over activate_mm. Architectures that do IPI based TLB 476 shootdowns should enable this. 447 shootdowns should enable this. 477 448 478 # 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 449 config ARCH_HAVE_NMI_SAFE_CMPXCHG 511 bool 450 bool 512 451 513 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 452 config HAVE_ALIGNED_STRUCT_PAGE 526 bool 453 bool 527 help 454 help 528 This makes sure that struct pages ar 455 This makes sure that struct pages are double word aligned and that 529 e.g. the SLUB allocator can perform 456 e.g. the SLUB allocator can perform double word atomic operations 530 on a struct page for better performa 457 on a struct page for better performance. However selecting this 531 might increase the size of a struct 458 might increase the size of a struct page by a word. 532 459 533 config HAVE_CMPXCHG_LOCAL 460 config HAVE_CMPXCHG_LOCAL 534 bool 461 bool 535 462 536 config HAVE_CMPXCHG_DOUBLE 463 config HAVE_CMPXCHG_DOUBLE 537 bool 464 bool 538 465 539 config ARCH_WEAK_RELEASE_ACQUIRE 466 config ARCH_WEAK_RELEASE_ACQUIRE 540 bool 467 bool 541 468 542 config ARCH_WANT_IPC_PARSE_VERSION 469 config ARCH_WANT_IPC_PARSE_VERSION 543 bool 470 bool 544 471 545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 472 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 546 bool 473 bool 547 474 548 config ARCH_WANT_OLD_COMPAT_IPC 475 config ARCH_WANT_OLD_COMPAT_IPC 549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 476 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 550 bool 477 bool 551 478 552 config HAVE_ARCH_SECCOMP 479 config HAVE_ARCH_SECCOMP 553 bool 480 bool 554 help 481 help 555 An arch should select this symbol to 482 An arch should select this symbol to support seccomp mode 1 (the fixed 556 syscall policy), and must provide an 483 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 557 and compat syscalls if the asm-gener 484 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 558 - __NR_seccomp_read_32 485 - __NR_seccomp_read_32 559 - __NR_seccomp_write_32 486 - __NR_seccomp_write_32 560 - __NR_seccomp_exit_32 487 - __NR_seccomp_exit_32 561 - __NR_seccomp_sigreturn_32 488 - __NR_seccomp_sigreturn_32 562 489 563 config HAVE_ARCH_SECCOMP_FILTER 490 config HAVE_ARCH_SECCOMP_FILTER 564 bool 491 bool 565 select HAVE_ARCH_SECCOMP 492 select HAVE_ARCH_SECCOMP 566 help 493 help 567 An arch should select this symbol if 494 An arch should select this symbol if it provides all of these things: 568 - all the requirements for HAVE_ARCH 495 - all the requirements for HAVE_ARCH_SECCOMP 569 - syscall_get_arch() 496 - syscall_get_arch() 570 - syscall_get_arguments() 497 - syscall_get_arguments() 571 - syscall_rollback() 498 - syscall_rollback() 572 - syscall_set_return_value() 499 - syscall_set_return_value() 573 - SIGSYS siginfo_t support 500 - SIGSYS siginfo_t support 574 - secure_computing is called from a 501 - secure_computing is called from a ptrace_event()-safe context 575 - secure_computing return value is c 502 - secure_computing return value is checked and a return value of -1 576 results in the system call being s 503 results in the system call being skipped immediately. 577 - seccomp syscall wired up 504 - seccomp syscall wired up 578 - if !HAVE_SPARSE_SYSCALL_NR, have S 505 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 506 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 580 COMPAT is supported, have the SECC 507 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 581 508 582 config SECCOMP 509 config SECCOMP 583 prompt "Enable seccomp to safely execu 510 prompt "Enable seccomp to safely execute untrusted bytecode" 584 def_bool y 511 def_bool y 585 depends on HAVE_ARCH_SECCOMP 512 depends on HAVE_ARCH_SECCOMP 586 help 513 help 587 This kernel feature is useful for nu 514 This kernel feature is useful for number crunching applications 588 that may need to handle untrusted by 515 that may need to handle untrusted bytecode during their 589 execution. By using pipes or other t 516 execution. By using pipes or other transports made available 590 to the process as file descriptors s 517 to the process as file descriptors supporting the read/write 591 syscalls, it's possible to isolate t 518 syscalls, it's possible to isolate those applications in their 592 own address space using seccomp. Onc 519 own address space using seccomp. Once seccomp is enabled via 593 prctl(PR_SET_SECCOMP) or the seccomp 520 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 594 disabled and the task is only allowe 521 disabled and the task is only allowed to execute a few safe 595 syscalls defined by each seccomp mod 522 syscalls defined by each seccomp mode. 596 523 597 If unsure, say Y. 524 If unsure, say Y. 598 525 599 config SECCOMP_FILTER 526 config SECCOMP_FILTER 600 def_bool y 527 def_bool y 601 depends on HAVE_ARCH_SECCOMP_FILTER && 528 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 602 help 529 help 603 Enable tasks to build secure computi 530 Enable tasks to build secure computing environments defined 604 in terms of Berkeley Packet Filter p 531 in terms of Berkeley Packet Filter programs which implement 605 task-defined system call filtering p 532 task-defined system call filtering polices. 606 533 607 See Documentation/userspace-api/secc 534 See Documentation/userspace-api/seccomp_filter.rst for details. 608 535 609 config SECCOMP_CACHE_DEBUG 536 config SECCOMP_CACHE_DEBUG 610 bool "Show seccomp filter cache status 537 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 611 depends on SECCOMP_FILTER && !HAVE_SPA 538 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 612 depends on PROC_FS 539 depends on PROC_FS 613 help 540 help 614 This enables the /proc/pid/seccomp_c 541 This enables the /proc/pid/seccomp_cache interface to monitor 615 seccomp cache data. The file format 542 seccomp cache data. The file format is subject to change. Reading 616 the file requires CAP_SYS_ADMIN. 543 the file requires CAP_SYS_ADMIN. 617 544 618 This option is for debugging only. E 545 This option is for debugging only. Enabling presents the risk that 619 an adversary may be able to infer th 546 an adversary may be able to infer the seccomp filter logic. 620 547 621 If unsure, say N. 548 If unsure, say N. 622 549 623 config HAVE_ARCH_STACKLEAK 550 config HAVE_ARCH_STACKLEAK 624 bool 551 bool 625 help 552 help 626 An architecture should select this i 553 An architecture should select this if it has the code which 627 fills the used part of the kernel st 554 fills the used part of the kernel stack with the STACKLEAK_POISON 628 value before returning from system c 555 value before returning from system calls. 629 556 630 config HAVE_STACKPROTECTOR 557 config HAVE_STACKPROTECTOR 631 bool 558 bool 632 help 559 help 633 An arch should select this symbol if 560 An arch should select this symbol if: 634 - it has implemented a stack canary 561 - it has implemented a stack canary (e.g. __stack_chk_guard) 635 562 636 config STACKPROTECTOR 563 config STACKPROTECTOR 637 bool "Stack Protector buffer overflow 564 bool "Stack Protector buffer overflow detection" 638 depends on HAVE_STACKPROTECTOR 565 depends on HAVE_STACKPROTECTOR 639 depends on $(cc-option,-fstack-protect 566 depends on $(cc-option,-fstack-protector) 640 default y 567 default y 641 help 568 help 642 This option turns on the "stack-prot 569 This option turns on the "stack-protector" GCC feature. This 643 feature puts, at the beginning of fu 570 feature puts, at the beginning of functions, a canary value on 644 the stack just before the return add 571 the stack just before the return address, and validates 645 the value just before actually retur 572 the value just before actually returning. Stack based buffer 646 overflows (that need to overwrite th 573 overflows (that need to overwrite this return address) now also 647 overwrite the canary, which gets det 574 overwrite the canary, which gets detected and the attack is then 648 neutralized via a kernel panic. 575 neutralized via a kernel panic. 649 576 650 Functions will have the stack-protec 577 Functions will have the stack-protector canary logic added if they 651 have an 8-byte or larger character a 578 have an 8-byte or larger character array on the stack. 652 579 653 This feature requires gcc version 4. 580 This feature requires gcc version 4.2 or above, or a distribution 654 gcc with the feature backported ("-f 581 gcc with the feature backported ("-fstack-protector"). 655 582 656 On an x86 "defconfig" build, this fe 583 On an x86 "defconfig" build, this feature adds canary checks to 657 about 3% of all kernel functions, wh 584 about 3% of all kernel functions, which increases kernel code size 658 by about 0.3%. 585 by about 0.3%. 659 586 660 config STACKPROTECTOR_STRONG 587 config STACKPROTECTOR_STRONG 661 bool "Strong Stack Protector" 588 bool "Strong Stack Protector" 662 depends on STACKPROTECTOR 589 depends on STACKPROTECTOR 663 depends on $(cc-option,-fstack-protect 590 depends on $(cc-option,-fstack-protector-strong) 664 default y 591 default y 665 help 592 help 666 Functions will have the stack-protec 593 Functions will have the stack-protector canary logic added in any 667 of the following conditions: 594 of the following conditions: 668 595 669 - local variable's address used as p 596 - local variable's address used as part of the right hand side of an 670 assignment or function argument 597 assignment or function argument 671 - local variable is an array (or uni 598 - local variable is an array (or union containing an array), 672 regardless of array type or length 599 regardless of array type or length 673 - uses register local variables 600 - uses register local variables 674 601 675 This feature requires gcc version 4. 602 This feature requires gcc version 4.9 or above, or a distribution 676 gcc with the feature backported ("-f 603 gcc with the feature backported ("-fstack-protector-strong"). 677 604 678 On an x86 "defconfig" build, this fe 605 On an x86 "defconfig" build, this feature adds canary checks to 679 about 20% of all kernel functions, w 606 about 20% of all kernel functions, which increases the kernel code 680 size by about 2%. 607 size by about 2%. 681 608 682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 609 config ARCH_SUPPORTS_SHADOW_CALL_STACK 683 bool 610 bool 684 help 611 help 685 An architecture should select this i !! 612 An architecture should select this if it supports Clang's Shadow 686 Shadow Call Stack and implements run !! 613 Call Stack and implements runtime support for shadow stack 687 switching. 614 switching. 688 615 689 config SHADOW_CALL_STACK 616 config SHADOW_CALL_STACK 690 bool "Shadow Call Stack" !! 617 bool "Clang Shadow Call Stack" 691 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 618 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK 692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 619 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 693 depends on MMU !! 620 help 694 help !! 621 This option enables Clang's Shadow Call Stack, which uses a 695 This option enables the compiler's S !! 622 shadow stack to protect function return addresses from being 696 uses a shadow stack to protect funct !! 623 overwritten by an attacker. More information can be found in 697 being overwritten by an attacker. Mo !! 624 Clang's documentation: 698 in the compiler's documentation: << 699 625 700 - Clang: https://clang.llvm.org/docs !! 626 https://clang.llvm.org/docs/ShadowCallStack.html 701 - GCC: https://gcc.gnu.org/onlinedoc << 702 627 703 Note that security guarantees in the 628 Note that security guarantees in the kernel differ from the 704 ones documented for user space. The 629 ones documented for user space. The kernel must store addresses 705 of shadow stacks in memory, which me 630 of shadow stacks in memory, which means an attacker capable of 706 reading and writing arbitrary memory 631 reading and writing arbitrary memory may be able to locate them 707 and hijack control flow by modifying 632 and hijack control flow by modifying the stacks. 708 633 709 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 << 717 bool << 718 help << 719 Selected if the kernel will be built << 720 << 721 config LTO_CLANG << 722 bool << 723 select LTO << 724 help << 725 Selected if the kernel will be built << 726 << 727 config ARCH_SUPPORTS_LTO_CLANG << 728 bool << 729 help << 730 An architecture should select this o << 731 - compiling with Clang, << 732 - compiling inline assembly with Cla << 733 - and linking with LLD. << 734 << 735 config ARCH_SUPPORTS_LTO_CLANG_THIN << 736 bool << 737 help << 738 An architecture should select this o << 739 ThinLTO mode. << 740 << 741 config HAS_LTO_CLANG << 742 def_bool y << 743 depends on CC_IS_CLANG && LD_IS_LLD && << 744 depends on $(success,$(NM) --help | he << 745 depends on $(success,$(AR) --help | he << 746 depends on ARCH_SUPPORTS_LTO_CLANG << 747 depends on !FTRACE_MCOUNT_USE_RECORDMC << 748 # https://github.com/ClangBuiltLinux/l << 749 depends on (!KASAN || KASAN_HW_TAGS || << 750 depends on (!KCOV || CLANG_VERSION >= << 751 depends on !GCOV_KERNEL << 752 help << 753 The compiler and Kconfig options sup << 754 LTO. << 755 << 756 choice << 757 prompt "Link Time Optimization (LTO)" << 758 default LTO_NONE << 759 help << 760 This option enables Link Time Optimi << 761 compiler to optimize binaries global << 762 << 763 If unsure, select LTO_NONE. Note tha << 764 so it's disabled by default. << 765 << 766 config LTO_NONE << 767 bool "None" << 768 help << 769 Build the kernel normally, without L << 770 << 771 config LTO_CLANG_FULL << 772 bool "Clang Full LTO (EXPERIMENTAL)" << 773 depends on HAS_LTO_CLANG << 774 depends on !COMPILE_TEST << 775 select LTO_CLANG << 776 help << 777 This option enables Clang's full Lin << 778 allows the compiler to optimize the << 779 this option, the compiler generates << 780 object files, and the actual compila << 781 the LTO link step, which may take se << 782 kernel configuration. More informati << 783 documentation: << 784 << 785 https://llvm.org/docs/LinkTimeOpti << 786 << 787 During link time, this option can us << 788 may take much longer than the ThinLT << 789 << 790 config LTO_CLANG_THIN << 791 bool "Clang ThinLTO (EXPERIMENTAL)" << 792 depends on HAS_LTO_CLANG && ARCH_SUPPO << 793 select LTO_CLANG << 794 help << 795 This option enables Clang's ThinLTO, << 796 optimization and faster incremental << 797 CONFIG_LTO_CLANG_FULL option. More i << 798 from Clang's documentation: << 799 << 800 https://clang.llvm.org/docs/ThinLT << 801 << 802 If unsure, say Y. << 803 endchoice << 804 << 805 config ARCH_SUPPORTS_CFI_CLANG << 806 bool << 807 help << 808 An architecture should select this o << 809 Control-Flow Integrity (CFI) checkin << 810 << 811 config ARCH_USES_CFI_TRAPS << 812 bool << 813 << 814 config CFI_CLANG << 815 bool "Use Clang's Control Flow Integri << 816 depends on ARCH_SUPPORTS_CFI_CLANG << 817 depends on $(cc-option,-fsanitize=kcfi << 818 help << 819 This option enables Clang's forward- << 820 (CFI) checking, where the compiler i << 821 indirect function call to ensure the << 822 the correct static type. This restri << 823 makes it more difficult for an attac << 824 the modification of stored function << 825 found from Clang's documentation: << 826 << 827 https://clang.llvm.org/docs/Contro << 828 << 829 config CFI_PERMISSIVE << 830 bool "Use CFI in permissive mode" << 831 depends on CFI_CLANG << 832 help << 833 When selected, Control Flow Integrit << 834 warning instead of a kernel panic. T << 835 for finding indirect call type misma << 836 << 837 If unsure, say N. << 838 << 839 config HAVE_ARCH_WITHIN_STACK_FRAMES 634 config HAVE_ARCH_WITHIN_STACK_FRAMES 840 bool 635 bool 841 help 636 help 842 An architecture should select this i 637 An architecture should select this if it can walk the kernel stack 843 frames to determine if an object is 638 frames to determine if an object is part of either the arguments 844 or local variables (i.e. that it exc 639 or local variables (i.e. that it excludes saved return addresses, 845 and similar) by implementing an inli 640 and similar) by implementing an inline arch_within_stack_frames(), 846 which is used by CONFIG_HARDENED_USE 641 which is used by CONFIG_HARDENED_USERCOPY. 847 642 848 config HAVE_CONTEXT_TRACKING_USER !! 643 config HAVE_CONTEXT_TRACKING 849 bool 644 bool 850 help 645 help 851 Provide kernel/user boundaries probe 646 Provide kernel/user boundaries probes necessary for subsystems 852 that need it, such as userspace RCU 647 that need it, such as userspace RCU extended quiescent state. 853 Syscalls need to be wrapped inside u 648 Syscalls need to be wrapped inside user_exit()-user_enter(), either 854 optimized behind static key or throu 649 optimized behind static key or through the slow path using TIF_NOHZ 855 flag. Exceptions handlers must be wr 650 flag. Exceptions handlers must be wrapped as well. Irqs are already 856 protected inside ct_irq_enter/ct_irq !! 651 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal 857 handling on irq exit still need to b 652 handling on irq exit still need to be protected. 858 653 859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 654 config HAVE_CONTEXT_TRACKING_OFFSTACK 860 bool 655 bool 861 help 656 help 862 Architecture neither relies on excep 657 Architecture neither relies on exception_enter()/exception_exit() 863 nor on schedule_user(). Also preempt 658 nor on schedule_user(). Also preempt_schedule_notrace() and 864 preempt_schedule_irq() can't be call 659 preempt_schedule_irq() can't be called in a preemptible section 865 while context tracking is CONTEXT_US 660 while context tracking is CONTEXT_USER. This feature reflects a sane 866 entry implementation where the follo 661 entry implementation where the following requirements are met on 867 critical entry code, ie: before user 662 critical entry code, ie: before user_exit() or after user_enter(): 868 663 869 - Critical entry code isn't preempti 664 - Critical entry code isn't preemptible (or better yet: 870 not interruptible). 665 not interruptible). 871 - No use of RCU read side critical s !! 666 - No use of RCU read side critical sections, unless rcu_nmi_enter() 872 got called. 667 got called. 873 - No use of instrumentation, unless 668 - No use of instrumentation, unless instrumentation_begin() got 874 called. 669 called. 875 670 876 config HAVE_TIF_NOHZ 671 config HAVE_TIF_NOHZ 877 bool 672 bool 878 help 673 help 879 Arch relies on TIF_NOHZ and syscall 674 Arch relies on TIF_NOHZ and syscall slow path to implement context 880 tracking calls to user_enter()/user_ 675 tracking calls to user_enter()/user_exit(). 881 676 882 config HAVE_VIRT_CPU_ACCOUNTING 677 config HAVE_VIRT_CPU_ACCOUNTING 883 bool 678 bool 884 679 885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 680 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 886 bool 681 bool 887 help 682 help 888 Architecture has its own way to acco 683 Architecture has its own way to account idle CPU time and therefore 889 doesn't implement vtime_account_idle 684 doesn't implement vtime_account_idle(). 890 685 891 config ARCH_HAS_SCALED_CPUTIME 686 config ARCH_HAS_SCALED_CPUTIME 892 bool 687 bool 893 688 894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 689 config HAVE_VIRT_CPU_ACCOUNTING_GEN 895 bool 690 bool 896 default y if 64BIT 691 default y if 64BIT 897 help 692 help 898 With VIRT_CPU_ACCOUNTING_GEN, cputim 693 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 899 Before enabling this option, arch co 694 Before enabling this option, arch code must be audited 900 to ensure there are no races in conc 695 to ensure there are no races in concurrent read/write of 901 cputime_t. For example, reading/writ 696 cputime_t. For example, reading/writing 64-bit cputime_t on 902 some 32-bit arches may require multi 697 some 32-bit arches may require multiple accesses, so proper 903 locking is needed to protect against 698 locking is needed to protect against concurrent accesses. 904 699 905 config HAVE_IRQ_TIME_ACCOUNTING 700 config HAVE_IRQ_TIME_ACCOUNTING 906 bool 701 bool 907 help 702 help 908 Archs need to ensure they use a high 703 Archs need to ensure they use a high enough resolution clock to 909 support irq time accounting and then 704 support irq time accounting and then call enable_sched_clock_irqtime(). 910 705 911 config HAVE_MOVE_PUD 706 config HAVE_MOVE_PUD 912 bool 707 bool 913 help 708 help 914 Architectures that select this are a 709 Architectures that select this are able to move page tables at the 915 PUD level. If there are only 3 page 710 PUD level. If there are only 3 page table levels, the move effectively 916 happens at the PGD level. 711 happens at the PGD level. 917 712 918 config HAVE_MOVE_PMD 713 config HAVE_MOVE_PMD 919 bool 714 bool 920 help 715 help 921 Archs that select this are able to m 716 Archs that select this are able to move page tables at the PMD level. 922 717 923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 718 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 924 bool 719 bool 925 720 926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 721 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 927 bool 722 bool 928 723 929 config HAVE_ARCH_HUGE_VMAP 724 config HAVE_ARCH_HUGE_VMAP 930 bool 725 bool 931 726 932 # << 933 # Archs that select this would be capable of << 934 # arch_vmap_pmd_supported() returns true). Th << 935 # must be used to enable allocations to use h << 936 # << 937 config HAVE_ARCH_HUGE_VMALLOC << 938 depends on HAVE_ARCH_HUGE_VMAP << 939 bool << 940 << 941 config ARCH_WANT_HUGE_PMD_SHARE 727 config ARCH_WANT_HUGE_PMD_SHARE 942 bool 728 bool 943 729 944 # 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 730 config HAVE_ARCH_SOFT_DIRTY 953 bool 731 bool 954 732 955 config HAVE_MOD_ARCH_SPECIFIC 733 config HAVE_MOD_ARCH_SPECIFIC 956 bool 734 bool 957 help 735 help 958 The arch uses struct mod_arch_specif 736 The arch uses struct mod_arch_specific to store data. Many arches 959 just need a simple module loader wit 737 just need a simple module loader without arch specific data - those 960 should not enable this. 738 should not enable this. 961 739 962 config MODULES_USE_ELF_RELA 740 config MODULES_USE_ELF_RELA 963 bool 741 bool 964 help 742 help 965 Modules only use ELF RELA relocation 743 Modules only use ELF RELA relocations. Modules with ELF REL 966 relocations will give an error. 744 relocations will give an error. 967 745 968 config MODULES_USE_ELF_REL 746 config MODULES_USE_ELF_REL 969 bool 747 bool 970 help 748 help 971 Modules only use ELF REL relocations 749 Modules only use ELF REL relocations. Modules with ELF RELA 972 relocations will give an error. 750 relocations will give an error. 973 751 974 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 752 config HAVE_IRQ_EXIT_ON_IRQ_STACK 989 bool 753 bool 990 help 754 help 991 Architecture doesn't only execute th 755 Architecture doesn't only execute the irq handler on the irq stack 992 but also irq_exit(). This way we can 756 but also irq_exit(). This way we can process softirqs on this irq 993 stack instead of switching to a new 757 stack instead of switching to a new one when we call __do_softirq() 994 in the end of an hardirq. 758 in the end of an hardirq. 995 This spares a stack switch and impro 759 This spares a stack switch and improves cache usage on softirq 996 processing. 760 processing. 997 761 998 config HAVE_SOFTIRQ_ON_OWN_STACK << 999 bool << 1000 help << 1001 Architecture provides a function to << 1002 separate stack. << 1003 << 1004 config SOFTIRQ_ON_OWN_STACK << 1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && << 1006 << 1007 config ALTERNATE_USER_ADDRESS_SPACE << 1008 bool << 1009 help << 1010 Architectures set this when the CPU << 1011 spaces for kernel and user space po << 1012 access_ok() check on a __user point << 1013 << 1014 config PGTABLE_LEVELS 762 config PGTABLE_LEVELS 1015 int 763 int 1016 default 2 764 default 2 1017 765 1018 config ARCH_HAS_ELF_RANDOMIZE 766 config ARCH_HAS_ELF_RANDOMIZE 1019 bool 767 bool 1020 help 768 help 1021 An architecture supports choosing r 769 An architecture supports choosing randomized locations for 1022 stack, mmap, brk, and ET_DYN. Defin 770 stack, mmap, brk, and ET_DYN. Defined functions: 1023 - arch_mmap_rnd() 771 - arch_mmap_rnd() 1024 - arch_randomize_brk() 772 - arch_randomize_brk() 1025 773 1026 config HAVE_ARCH_MMAP_RND_BITS 774 config HAVE_ARCH_MMAP_RND_BITS 1027 bool 775 bool 1028 help 776 help 1029 An arch should select this symbol i 777 An arch should select this symbol if it supports setting a variable 1030 number of bits for use in establish 778 number of bits for use in establishing the base address for mmap 1031 allocations, has MMU enabled and pr 779 allocations, has MMU enabled and provides values for both: 1032 - ARCH_MMAP_RND_BITS_MIN 780 - ARCH_MMAP_RND_BITS_MIN 1033 - ARCH_MMAP_RND_BITS_MAX 781 - ARCH_MMAP_RND_BITS_MAX 1034 782 1035 config HAVE_EXIT_THREAD 783 config HAVE_EXIT_THREAD 1036 bool 784 bool 1037 help 785 help 1038 An architecture implements exit_thr 786 An architecture implements exit_thread. 1039 787 1040 config ARCH_MMAP_RND_BITS_MIN 788 config ARCH_MMAP_RND_BITS_MIN 1041 int 789 int 1042 790 1043 config ARCH_MMAP_RND_BITS_MAX 791 config ARCH_MMAP_RND_BITS_MAX 1044 int 792 int 1045 793 1046 config ARCH_MMAP_RND_BITS_DEFAULT 794 config ARCH_MMAP_RND_BITS_DEFAULT 1047 int 795 int 1048 796 1049 config ARCH_MMAP_RND_BITS 797 config ARCH_MMAP_RND_BITS 1050 int "Number of bits to use for ASLR o 798 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 799 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1052 default ARCH_MMAP_RND_BITS_DEFAULT if 800 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1053 default ARCH_MMAP_RND_BITS_MIN 801 default ARCH_MMAP_RND_BITS_MIN 1054 depends on HAVE_ARCH_MMAP_RND_BITS 802 depends on HAVE_ARCH_MMAP_RND_BITS 1055 help 803 help 1056 This value can be used to select th 804 This value can be used to select the number of bits to use to 1057 determine the random offset to the 805 determine the random offset to the base address of vma regions 1058 resulting from mmap allocations. Th 806 resulting from mmap allocations. This value will be bounded 1059 by the architecture's minimum and m 807 by the architecture's minimum and maximum supported values. 1060 808 1061 This value can be changed after boo 809 This value can be changed after boot using the 1062 /proc/sys/vm/mmap_rnd_bits tunable 810 /proc/sys/vm/mmap_rnd_bits tunable 1063 811 1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 812 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1065 bool 813 bool 1066 help 814 help 1067 An arch should select this symbol i 815 An arch should select this symbol if it supports running applications 1068 in compatibility mode, supports set 816 in compatibility mode, supports setting a variable number of bits for 1069 use in establishing the base addres 817 use in establishing the base address for mmap allocations, has MMU 1070 enabled and provides values for bot 818 enabled and provides values for both: 1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 819 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 820 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1073 821 1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 822 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1075 int 823 int 1076 824 1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 825 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1078 int 826 int 1079 827 1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 828 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1081 int 829 int 1082 830 1083 config ARCH_MMAP_RND_COMPAT_BITS 831 config ARCH_MMAP_RND_COMPAT_BITS 1084 int "Number of bits to use for ASLR o 832 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 833 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 834 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 835 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 836 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1089 help 837 help 1090 This value can be used to select th 838 This value can be used to select the number of bits to use to 1091 determine the random offset to the 839 determine the random offset to the base address of vma regions 1092 resulting from mmap allocations for 840 resulting from mmap allocations for compatible applications This 1093 value will be bounded by the archit 841 value will be bounded by the architecture's minimum and maximum 1094 supported values. 842 supported values. 1095 843 1096 This value can be changed after boo 844 This value can be changed after boot using the 1097 /proc/sys/vm/mmap_rnd_compat_bits t 845 /proc/sys/vm/mmap_rnd_compat_bits tunable 1098 846 1099 config HAVE_ARCH_COMPAT_MMAP_BASES 847 config HAVE_ARCH_COMPAT_MMAP_BASES 1100 bool 848 bool 1101 help 849 help 1102 This allows 64bit applications to i 850 This allows 64bit applications to invoke 32-bit mmap() syscall 1103 and vice-versa 32-bit applications 851 and vice-versa 32-bit applications to call 64-bit mmap(). 1104 Required for applications doing dif 852 Required for applications doing different bitness syscalls. 1105 853 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 << 1190 def_bool y << 1191 depends on !PAGE_SIZE_64KB << 1192 depends on PAGE_SIZE_LESS_THAN_256KB << 1193 << 1194 config PAGE_SIZE_LESS_THAN_256KB << 1195 def_bool y << 1196 depends on !PAGE_SIZE_256KB << 1197 << 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 854 # This allows to use a set of generic functions to determine mmap base 1208 # address by giving priority to top-down sche 855 # address by giving priority to top-down scheme only if the process 1209 # is not in legacy mode (compat task, unlimit 856 # is not in legacy mode (compat task, unlimited stack size or 1210 # sysctl_legacy_va_layout). 857 # sysctl_legacy_va_layout). 1211 # Architecture that selects this option can p 858 # Architecture that selects this option can provide its own version of: 1212 # - STACK_RND_MASK 859 # - STACK_RND_MASK 1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 860 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1214 bool 861 bool 1215 depends on MMU 862 depends on MMU 1216 select ARCH_HAS_ELF_RANDOMIZE 863 select ARCH_HAS_ELF_RANDOMIZE 1217 864 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 865 config HAVE_STACK_VALIDATION 1235 bool 866 bool 1236 help 867 help 1237 Architecture supports objtool compi !! 868 Architecture supports the 'objtool check' host tool command, which 1238 validation. !! 869 performs compile-time stack metadata validation. 1239 870 1240 config HAVE_RELIABLE_STACKTRACE 871 config HAVE_RELIABLE_STACKTRACE 1241 bool 872 bool 1242 help 873 help 1243 Architecture has either save_stack_ 874 Architecture has either save_stack_trace_tsk_reliable() or 1244 arch_stack_walk_reliable() function 875 arch_stack_walk_reliable() function which only returns a stack trace 1245 if it can guarantee the trace is re 876 if it can guarantee the trace is reliable. 1246 877 1247 config HAVE_ARCH_HASH 878 config HAVE_ARCH_HASH 1248 bool 879 bool 1249 default n 880 default n 1250 help 881 help 1251 If this is set, the architecture pr 882 If this is set, the architecture provides an <asm/hash.h> 1252 file which provides platform-specif 883 file which provides platform-specific implementations of some 1253 functions in <linux/hash.h> or fs/n 884 functions in <linux/hash.h> or fs/namei.c. 1254 885 1255 config HAVE_ARCH_NVRAM_OPS 886 config HAVE_ARCH_NVRAM_OPS 1256 bool 887 bool 1257 888 1258 config ISA_BUS_API 889 config ISA_BUS_API 1259 def_bool ISA 890 def_bool ISA 1260 891 1261 # 892 # 1262 # ABI hall of shame 893 # ABI hall of shame 1263 # 894 # 1264 config CLONE_BACKWARDS 895 config CLONE_BACKWARDS 1265 bool 896 bool 1266 help 897 help 1267 Architecture has tls passed as the 898 Architecture has tls passed as the 4th argument of clone(2), 1268 not the 5th one. 899 not the 5th one. 1269 900 1270 config CLONE_BACKWARDS2 901 config CLONE_BACKWARDS2 1271 bool 902 bool 1272 help 903 help 1273 Architecture has the first two argu 904 Architecture has the first two arguments of clone(2) swapped. 1274 905 1275 config CLONE_BACKWARDS3 906 config CLONE_BACKWARDS3 1276 bool 907 bool 1277 help 908 help 1278 Architecture has tls passed as the 909 Architecture has tls passed as the 3rd argument of clone(2), 1279 not the 5th one. 910 not the 5th one. 1280 911 1281 config ODD_RT_SIGACTION 912 config ODD_RT_SIGACTION 1282 bool 913 bool 1283 help 914 help 1284 Architecture has unusual rt_sigacti 915 Architecture has unusual rt_sigaction(2) arguments 1285 916 1286 config OLD_SIGSUSPEND 917 config OLD_SIGSUSPEND 1287 bool 918 bool 1288 help 919 help 1289 Architecture has old sigsuspend(2) 920 Architecture has old sigsuspend(2) syscall, of one-argument variety 1290 921 1291 config OLD_SIGSUSPEND3 922 config OLD_SIGSUSPEND3 1292 bool 923 bool 1293 help 924 help 1294 Even weirder antique ABI - three-ar 925 Even weirder antique ABI - three-argument sigsuspend(2) 1295 926 1296 config OLD_SIGACTION 927 config OLD_SIGACTION 1297 bool 928 bool 1298 help 929 help 1299 Architecture has old sigaction(2) s 930 Architecture has old sigaction(2) syscall. Nope, not the same 1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 931 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1301 but fairly different variant of sig 932 but fairly different variant of sigaction(2), thanks to OSF/1 1302 compatibility... 933 compatibility... 1303 934 1304 config COMPAT_OLD_SIGACTION 935 config COMPAT_OLD_SIGACTION 1305 bool 936 bool 1306 937 1307 config COMPAT_32BIT_TIME 938 config COMPAT_32BIT_TIME 1308 bool "Provide system calls for 32-bit 939 bool "Provide system calls for 32-bit time_t" 1309 default !64BIT || COMPAT 940 default !64BIT || COMPAT 1310 help 941 help 1311 This enables 32 bit time_t support 942 This enables 32 bit time_t support in addition to 64 bit time_t support. 1312 This is relevant on all 32-bit arch 943 This is relevant on all 32-bit architectures, and 64-bit architectures 1313 as part of compat syscall handling. 944 as part of compat syscall handling. 1314 945 1315 config ARCH_NO_PREEMPT 946 config ARCH_NO_PREEMPT 1316 bool 947 bool 1317 948 1318 config ARCH_SUPPORTS_RT 949 config ARCH_SUPPORTS_RT 1319 bool 950 bool 1320 951 1321 config CPU_NO_EFFICIENT_FFS 952 config CPU_NO_EFFICIENT_FFS 1322 def_bool n 953 def_bool n 1323 954 1324 config HAVE_ARCH_VMAP_STACK 955 config HAVE_ARCH_VMAP_STACK 1325 def_bool n 956 def_bool n 1326 help 957 help 1327 An arch should select this symbol i 958 An arch should select this symbol if it can support kernel stacks 1328 in vmalloc space. This means: 959 in vmalloc space. This means: 1329 960 1330 - vmalloc space must be large enoug 961 - vmalloc space must be large enough to hold many kernel stacks. 1331 This may rule out many 32-bit arc 962 This may rule out many 32-bit architectures. 1332 963 1333 - Stacks in vmalloc space need to w 964 - Stacks in vmalloc space need to work reliably. For example, if 1334 vmap page tables are created on d 965 vmap page tables are created on demand, either this mechanism 1335 needs to work while the stack poi 966 needs to work while the stack points to a virtual address with 1336 unpopulated page tables or arch c 967 unpopulated page tables or arch code (switch_to() and switch_mm(), 1337 most likely) needs to ensure that 968 most likely) needs to ensure that the stack's page table entries 1338 are populated before running on a 969 are populated before running on a possibly unpopulated stack. 1339 970 1340 - If the stack overflows into a gua 971 - If the stack overflows into a guard page, something reasonable 1341 should happen. The definition of 972 should happen. The definition of "reasonable" is flexible, but 1342 instantly rebooting without loggi 973 instantly rebooting without logging anything would be unfriendly. 1343 974 1344 config VMAP_STACK 975 config VMAP_STACK 1345 default y 976 default y 1346 bool "Use a virtually-mapped stack" 977 bool "Use a virtually-mapped stack" 1347 depends on HAVE_ARCH_VMAP_STACK 978 depends on HAVE_ARCH_VMAP_STACK 1348 depends on !KASAN || KASAN_HW_TAGS || 979 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1349 help 980 help 1350 Enable this if you want the use vir 981 Enable this if you want the use virtually-mapped kernel stacks 1351 with guard pages. This causes kern 982 with guard pages. This causes kernel stack overflows to be 1352 caught immediately rather than caus 983 caught immediately rather than causing difficult-to-diagnose 1353 corruption. 984 corruption. 1354 985 1355 To use this with software KASAN mod 986 To use this with software KASAN modes, the architecture must support 1356 backing virtual mappings with real 987 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1357 must be enabled. 988 must be enabled. 1358 989 1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET << 1360 def_bool n << 1361 help << 1362 An arch should select this symbol i << 1363 offset randomization with calls to << 1364 during syscall entry and choose_ran << 1365 syscall exit. Careful removal of -f << 1366 -fstack-protector should also be ap << 1367 closely examined, as the artificial << 1368 to the compiler, so it will attempt << 1369 of the static branch state. << 1370 << 1371 config RANDOMIZE_KSTACK_OFFSET << 1372 bool "Support for randomizing kernel << 1373 default y << 1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK << 1375 depends on INIT_STACK_NONE || !CC_IS_ << 1376 help << 1377 The kernel stack offset can be rand << 1378 roughly 5 bits of entropy, frustrat << 1379 attacks that depend on stack addres << 1380 cross-syscall address exposures. << 1381 << 1382 The feature is controlled via the " << 1383 kernel boot param, and if turned of << 1384 of static branches (see JUMP_LABEL) << 1385 << 1386 If unsure, say Y. << 1387 << 1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT << 1389 bool "Default state of kernel stack o << 1390 depends on RANDOMIZE_KSTACK_OFFSET << 1391 help << 1392 Kernel stack offset randomization i << 1393 "randomize_kstack_offset=on/off", a << 1394 boot state. << 1395 << 1396 config ARCH_OPTIONAL_KERNEL_RWX 990 config ARCH_OPTIONAL_KERNEL_RWX 1397 def_bool n 991 def_bool n 1398 992 1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 993 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1400 def_bool n 994 def_bool n 1401 995 1402 config ARCH_HAS_STRICT_KERNEL_RWX 996 config ARCH_HAS_STRICT_KERNEL_RWX 1403 def_bool n 997 def_bool n 1404 998 1405 config STRICT_KERNEL_RWX 999 config STRICT_KERNEL_RWX 1406 bool "Make kernel text and rodata rea 1000 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1001 depends on ARCH_HAS_STRICT_KERNEL_RWX 1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1002 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1409 help 1003 help 1410 If this is set, kernel text and rod 1004 If this is set, kernel text and rodata memory will be made read-only, 1411 and non-text memory will be made no 1005 and non-text memory will be made non-executable. This provides 1412 protection against certain security 1006 protection against certain security exploits (e.g. executing the heap 1413 or modifying text) 1007 or modifying text) 1414 1008 1415 These features are considered stand 1009 These features are considered standard security practice these days. 1416 You should say Y here in almost all 1010 You should say Y here in almost all cases. 1417 1011 1418 config ARCH_HAS_STRICT_MODULE_RWX 1012 config ARCH_HAS_STRICT_MODULE_RWX 1419 def_bool n 1013 def_bool n 1420 1014 1421 config STRICT_MODULE_RWX 1015 config STRICT_MODULE_RWX 1422 bool "Set loadable kernel module data 1016 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 1017 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1018 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1425 help 1019 help 1426 If this is set, module text and rod 1020 If this is set, module text and rodata memory will be made read-only, 1427 and non-text memory will be made no 1021 and non-text memory will be made non-executable. This provides 1428 protection against certain security 1022 protection against certain security exploits (e.g. writing to text) 1429 1023 1430 # select if the architecture provides an asm/ 1024 # select if the architecture provides an asm/dma-direct.h header 1431 config ARCH_HAS_PHYS_TO_DMA 1025 config ARCH_HAS_PHYS_TO_DMA 1432 bool 1026 bool 1433 1027 1434 config HAVE_ARCH_COMPILER_H 1028 config HAVE_ARCH_COMPILER_H 1435 bool 1029 bool 1436 help 1030 help 1437 An architecture can select this if 1031 An architecture can select this if it provides an 1438 asm/compiler.h header that should b 1032 asm/compiler.h header that should be included after 1439 linux/compiler-*.h in order to over 1033 linux/compiler-*.h in order to override macro definitions that those 1440 headers generally provide. 1034 headers generally provide. 1441 1035 1442 config HAVE_ARCH_PREL32_RELOCATIONS 1036 config HAVE_ARCH_PREL32_RELOCATIONS 1443 bool 1037 bool 1444 help 1038 help 1445 May be selected by an architecture 1039 May be selected by an architecture if it supports place-relative 1446 32-bit relocations, both in the too 1040 32-bit relocations, both in the toolchain and in the module loader, 1447 in which case relative references c 1041 in which case relative references can be used in special sections 1448 for PCI fixup, initcalls etc which 1042 for PCI fixup, initcalls etc which are only half the size on 64 bit 1449 architectures, and don't require ru 1043 architectures, and don't require runtime relocation on relocatable 1450 kernels. 1044 kernels. 1451 1045 1452 config ARCH_USE_MEMREMAP_PROT 1046 config ARCH_USE_MEMREMAP_PROT 1453 bool 1047 bool 1454 1048 1455 config LOCK_EVENT_COUNTS 1049 config LOCK_EVENT_COUNTS 1456 bool "Locking event counts collection 1050 bool "Locking event counts collection" 1457 depends on DEBUG_FS 1051 depends on DEBUG_FS 1458 help 1052 help 1459 Enable light-weight counting of var 1053 Enable light-weight counting of various locking related events 1460 in the system with minimal performa 1054 in the system with minimal performance impact. This reduces 1461 the chance of application behavior 1055 the chance of application behavior change because of timing 1462 differences. The counts are reporte 1056 differences. The counts are reported via debugfs. 1463 1057 1464 # Select if the architecture has support for 1058 # Select if the architecture has support for applying RELR relocations. 1465 config ARCH_HAS_RELR 1059 config ARCH_HAS_RELR 1466 bool 1060 bool 1467 1061 1468 config RELR 1062 config RELR 1469 bool "Use RELR relocation packing" 1063 bool "Use RELR relocation packing" 1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1064 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1471 default y 1065 default y 1472 help 1066 help 1473 Store the kernel's dynamic relocati 1067 Store the kernel's dynamic relocations in the RELR relocation packing 1474 format. Requires a compatible linke 1068 format. Requires a compatible linker (LLD supports this feature), as 1475 well as compatible NM and OBJCOPY u 1069 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1476 are compatible). 1070 are compatible). 1477 1071 1478 config ARCH_HAS_MEM_ENCRYPT 1072 config ARCH_HAS_MEM_ENCRYPT 1479 bool 1073 bool 1480 1074 1481 config ARCH_HAS_CC_PLATFORM << 1482 bool << 1483 << 1484 config HAVE_SPARSE_SYSCALL_NR 1075 config HAVE_SPARSE_SYSCALL_NR 1485 bool !! 1076 bool 1486 help !! 1077 help 1487 An architecture should select this !! 1078 An architecture should select this if its syscall numbering is sparse 1488 to save space. For example, MIPS ar 1079 to save space. For example, MIPS architecture has a syscall array with 1489 entries at 4000, 5000 and 6000 loca 1080 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1490 related optimizations for a given a 1081 related optimizations for a given architecture. 1491 1082 1492 config ARCH_HAS_VDSO_DATA 1083 config ARCH_HAS_VDSO_DATA 1493 bool 1084 bool 1494 1085 1495 config HAVE_STATIC_CALL 1086 config HAVE_STATIC_CALL 1496 bool 1087 bool 1497 1088 1498 config HAVE_STATIC_CALL_INLINE 1089 config HAVE_STATIC_CALL_INLINE 1499 bool 1090 bool 1500 depends on HAVE_STATIC_CALL 1091 depends on HAVE_STATIC_CALL 1501 select OBJTOOL << 1502 << 1503 config HAVE_PREEMPT_DYNAMIC << 1504 bool << 1505 << 1506 config HAVE_PREEMPT_DYNAMIC_CALL << 1507 bool << 1508 depends on HAVE_STATIC_CALL << 1509 select HAVE_PREEMPT_DYNAMIC << 1510 help << 1511 An architecture should select this << 1512 model being selected at boot time u << 1513 << 1514 Where an architecture selects HAVE_ << 1515 preemption function will be patched << 1516 << 1517 Where an architecture does not sele << 1518 call to a preemption function will << 1519 trampoline will be patched. << 1520 << 1521 It is strongly advised to support i << 1522 overhead. << 1523 << 1524 config HAVE_PREEMPT_DYNAMIC_KEY << 1525 bool << 1526 depends on HAVE_ARCH_JUMP_LABEL << 1527 select HAVE_PREEMPT_DYNAMIC << 1528 help << 1529 An architecture should select this << 1530 model being selected at boot time u << 1531 << 1532 Each preemption function will be gi << 1533 static key. This should have slight << 1534 static calls, as this effectively i << 1535 start of its callee. This may avoid << 1536 integrate better with CFI schemes. << 1537 << 1538 This will have greater overhead tha << 1539 the call to the preemption function << 1540 1092 1541 config ARCH_WANT_LD_ORPHAN_WARN 1093 config ARCH_WANT_LD_ORPHAN_WARN 1542 bool 1094 bool 1543 help 1095 help 1544 An arch should select this symbol o 1096 An arch should select this symbol once all linker sections are explicitly 1545 included, size-asserted, or discard 1097 included, size-asserted, or discarded in the linker scripts. This is 1546 important because we never want exp 1098 important because we never want expected sections to be placed heuristically 1547 by the linker, since the locations 1099 by the linker, since the locations of such sections can change between linker 1548 versions. 1100 versions. 1549 1101 1550 config HAVE_ARCH_PFN_VALID 1102 config HAVE_ARCH_PFN_VALID 1551 bool 1103 bool 1552 1104 1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1105 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1554 bool 1106 bool 1555 1107 1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK << 1557 bool << 1558 << 1559 config ARCH_SPLIT_ARG64 1108 config ARCH_SPLIT_ARG64 1560 bool 1109 bool 1561 help 1110 help 1562 If a 32-bit architecture requires 6 !! 1111 If a 32-bit architecture requires 64-bit arguments to be split into 1563 pairs of 32-bit arguments, select t !! 1112 pairs of 32-bit arguments, select this option. 1564 << 1565 config ARCH_HAS_ELFCORE_COMPAT << 1566 bool << 1567 << 1568 config ARCH_HAS_PARANOID_L1D_FLUSH << 1569 bool << 1570 << 1571 config ARCH_HAVE_TRACE_MMIO_ACCESS << 1572 bool << 1573 << 1574 config DYNAMIC_SIGFRAME << 1575 bool << 1576 << 1577 # Select, if arch has a named attribute group << 1578 config HAVE_ARCH_NODE_DEV_GROUP << 1579 bool << 1580 << 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 1113 1603 source "kernel/gcov/Kconfig" 1114 source "kernel/gcov/Kconfig" 1604 1115 1605 source "scripts/gcc-plugins/Kconfig" 1116 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 1117 1646 endmenu 1118 endmenu
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