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 << 47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL << 48 select HOTPLUG_CORE_SYNC << 49 << 50 config HOTPLUG_SPLIT_STARTUP << 51 bool << 52 select HOTPLUG_CORE_SYNC_FULL << 53 << 54 config HOTPLUG_PARALLEL << 55 bool 31 bool 56 select HOTPLUG_SPLIT_STARTUP << 57 32 58 config GENERIC_ENTRY 33 config GENERIC_ENTRY 59 bool !! 34 bool 60 35 61 config KPROBES 36 config KPROBES 62 bool "Kprobes" 37 bool "Kprobes" >> 38 depends on MODULES 63 depends on HAVE_KPROBES 39 depends on HAVE_KPROBES 64 select KALLSYMS 40 select KALLSYMS 65 select EXECMEM << 66 select NEED_TASKS_RCU << 67 help 41 help 68 Kprobes allows you to trap at almost 42 Kprobes allows you to trap at almost any kernel address and 69 execute a callback function. regist 43 execute a callback function. register_kprobe() establishes 70 a probepoint and specifies the callb 44 a probepoint and specifies the callback. Kprobes is useful 71 for kernel debugging, non-intrusive 45 for kernel debugging, non-intrusive instrumentation and testing. 72 If in doubt, say "N". 46 If in doubt, say "N". 73 47 74 config JUMP_LABEL 48 config JUMP_LABEL 75 bool "Optimize very unlikely/likely br 49 bool "Optimize very unlikely/likely branches" 76 depends on HAVE_ARCH_JUMP_LABEL 50 depends on HAVE_ARCH_JUMP_LABEL 77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 51 depends on CC_HAS_ASM_GOTO 78 help 52 help 79 This option enables a transparent br !! 53 This option enables a transparent branch optimization that 80 makes certain almost-always-true or !! 54 makes certain almost-always-true or almost-always-false branch 81 conditions even cheaper to execute w !! 55 conditions even cheaper to execute within the kernel. 82 !! 56 83 Certain performance-sensitive kernel !! 57 Certain performance-sensitive kernel code, such as trace points, 84 scheduler functionality, networking !! 58 scheduler functionality, networking code and KVM have such 85 branches and include support for thi !! 59 branches and include support for this optimization technique. 86 !! 60 87 If it is detected that the compiler !! 61 If it is detected that the compiler has support for "asm goto", 88 the kernel will compile such branche !! 62 the kernel will compile such branches with just a nop 89 instruction. When the condition flag !! 63 instruction. When the condition flag is toggled to true, the 90 nop will be converted to a jump inst !! 64 nop will be converted to a jump instruction to execute the 91 conditional block of instructions. !! 65 conditional block of instructions. 92 !! 66 93 This technique lowers overhead and s !! 67 This technique lowers overhead and stress on the branch prediction 94 of the processor and generally makes !! 68 of the processor and generally makes the kernel faster. The update 95 of the condition is slower, but thos !! 69 of the condition is slower, but those are always very rare. 96 70 97 ( On 32-bit x86, the necessary optio !! 71 ( On 32-bit x86, the necessary options added to the compiler 98 flags may increase the size of the !! 72 flags may increase the size of the kernel slightly. ) 99 73 100 config STATIC_KEYS_SELFTEST 74 config STATIC_KEYS_SELFTEST 101 bool "Static key selftest" 75 bool "Static key selftest" 102 depends on JUMP_LABEL 76 depends on JUMP_LABEL 103 help 77 help 104 Boot time self-test of the branch pa 78 Boot time self-test of the branch patching code. 105 79 106 config STATIC_CALL_SELFTEST 80 config STATIC_CALL_SELFTEST 107 bool "Static call selftest" 81 bool "Static call selftest" 108 depends on HAVE_STATIC_CALL 82 depends on HAVE_STATIC_CALL 109 help 83 help 110 Boot time self-test of the call patc 84 Boot time self-test of the call patching code. 111 85 112 config OPTPROBES 86 config OPTPROBES 113 def_bool y 87 def_bool y 114 depends on KPROBES && HAVE_OPTPROBES 88 depends on KPROBES && HAVE_OPTPROBES 115 select NEED_TASKS_RCU !! 89 select TASKS_RCU if PREEMPTION 116 90 117 config KPROBES_ON_FTRACE 91 config KPROBES_ON_FTRACE 118 def_bool y 92 def_bool y 119 depends on KPROBES && HAVE_KPROBES_ON_ 93 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 120 depends on DYNAMIC_FTRACE_WITH_REGS 94 depends on DYNAMIC_FTRACE_WITH_REGS 121 help 95 help 122 If function tracer is enabled and th !! 96 If function tracer is enabled and the arch supports full 123 passing of pt_regs to function traci !! 97 passing of pt_regs to function tracing, then kprobes can 124 optimize on top of function tracing. !! 98 optimize on top of function tracing. 125 99 126 config UPROBES 100 config UPROBES 127 def_bool n 101 def_bool n 128 depends on ARCH_SUPPORTS_UPROBES 102 depends on ARCH_SUPPORTS_UPROBES 129 help 103 help 130 Uprobes is the user-space counterpar 104 Uprobes is the user-space counterpart to kprobes: they 131 enable instrumentation applications 105 enable instrumentation applications (such as 'perf probe') 132 to establish unintrusive probes in u 106 to establish unintrusive probes in user-space binaries and 133 libraries, by executing handler func 107 libraries, by executing handler functions when the probes 134 are hit by user-space applications. 108 are hit by user-space applications. 135 109 136 ( These probes come in the form of s 110 ( These probes come in the form of single-byte breakpoints, 137 managed by the kernel and kept tra 111 managed by the kernel and kept transparent to the probed 138 application. ) 112 application. ) 139 113 140 config HAVE_64BIT_ALIGNED_ACCESS 114 config HAVE_64BIT_ALIGNED_ACCESS 141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 115 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 142 help 116 help 143 Some architectures require 64 bit ac 117 Some architectures require 64 bit accesses to be 64 bit 144 aligned, which also requires structs 118 aligned, which also requires structs containing 64 bit values 145 to be 64 bit aligned too. This inclu 119 to be 64 bit aligned too. This includes some 32 bit 146 architectures which can do 64 bit ac 120 architectures which can do 64 bit accesses, as well as 64 bit 147 architectures without unaligned acce 121 architectures without unaligned access. 148 122 149 This symbol should be selected by an 123 This symbol should be selected by an architecture if 64 bit 150 accesses are required to be 64 bit a 124 accesses are required to be 64 bit aligned in this way even 151 though it is not a 64 bit architectu 125 though it is not a 64 bit architecture. 152 126 153 See Documentation/core-api/unaligned 127 See Documentation/core-api/unaligned-memory-access.rst for 154 more information on the topic of una 128 more information on the topic of unaligned memory accesses. 155 129 156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 130 config HAVE_EFFICIENT_UNALIGNED_ACCESS 157 bool 131 bool 158 help 132 help 159 Some architectures are unable to per 133 Some architectures are unable to perform unaligned accesses 160 without the use of get_unaligned/put 134 without the use of get_unaligned/put_unaligned. Others are 161 unable to perform such accesses effi 135 unable to perform such accesses efficiently (e.g. trap on 162 unaligned access and require fixing 136 unaligned access and require fixing it up in the exception 163 handler.) 137 handler.) 164 138 165 This symbol should be selected by an 139 This symbol should be selected by an architecture if it can 166 perform unaligned accesses efficient 140 perform unaligned accesses efficiently to allow different 167 code paths to be selected for these 141 code paths to be selected for these cases. Some network 168 drivers, for example, could opt to n 142 drivers, for example, could opt to not fix up alignment 169 problems with received packets if do 143 problems with received packets if doing so would not help 170 much. 144 much. 171 145 172 See Documentation/core-api/unaligned 146 See Documentation/core-api/unaligned-memory-access.rst for more 173 information on the topic of unaligne 147 information on the topic of unaligned memory accesses. 174 148 175 config ARCH_USE_BUILTIN_BSWAP 149 config ARCH_USE_BUILTIN_BSWAP 176 bool 150 bool 177 help 151 help 178 Modern versions of GCC (since 4.4) h !! 152 Modern versions of GCC (since 4.4) have builtin functions 179 for handling byte-swapping. Using th !! 153 for handling byte-swapping. Using these, instead of the old 180 inline assembler that the architectu !! 154 inline assembler that the architecture code provides in the 181 __arch_bswapXX() macros, allows the !! 155 __arch_bswapXX() macros, allows the compiler to see what's 182 happening and offers more opportunit !! 156 happening and offers more opportunity for optimisation. In 183 particular, the compiler will be abl !! 157 particular, the compiler will be able to combine the byteswap 184 with a nearby load or store and use !! 158 with a nearby load or store and use load-and-swap or 185 store-and-swap instructions if the a !! 159 store-and-swap instructions if the architecture has them. It 186 should almost *never* result in code !! 160 should almost *never* result in code which is worse than the 187 hand-coded assembler in <asm/swab.h> !! 161 hand-coded assembler in <asm/swab.h>. But just in case it 188 does, the use of the builtins is opt !! 162 does, the use of the builtins is optional. 189 !! 163 190 Any architecture with load-and-swap !! 164 Any architecture with load-and-swap or store-and-swap 191 instructions should set this. And it !! 165 instructions should set this. And it shouldn't hurt to set it 192 on architectures that don't have suc !! 166 on architectures that don't have such instructions. 193 167 194 config KRETPROBES 168 config KRETPROBES 195 def_bool y 169 def_bool y 196 depends on KPROBES && (HAVE_KRETPROBES !! 170 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 << 203 171 204 config USER_RETURN_NOTIFIER 172 config USER_RETURN_NOTIFIER 205 bool 173 bool 206 depends on HAVE_USER_RETURN_NOTIFIER 174 depends on HAVE_USER_RETURN_NOTIFIER 207 help 175 help 208 Provide a kernel-internal notificati 176 Provide a kernel-internal notification when a cpu is about to 209 switch to user mode. 177 switch to user mode. 210 178 211 config HAVE_IOREMAP_PROT 179 config HAVE_IOREMAP_PROT 212 bool 180 bool 213 181 214 config HAVE_KPROBES 182 config HAVE_KPROBES 215 bool 183 bool 216 184 217 config HAVE_KRETPROBES 185 config HAVE_KRETPROBES 218 bool 186 bool 219 187 220 config HAVE_OPTPROBES 188 config HAVE_OPTPROBES 221 bool 189 bool 222 190 223 config HAVE_KPROBES_ON_FTRACE 191 config HAVE_KPROBES_ON_FTRACE 224 bool 192 bool 225 193 226 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 194 config HAVE_FUNCTION_ERROR_INJECTION 235 bool 195 bool 236 196 237 config HAVE_NMI 197 config HAVE_NMI 238 bool 198 bool 239 199 240 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 # 200 # 250 # An arch should select this if it provides al 201 # An arch should select this if it provides all these things: 251 # 202 # 252 # task_pt_regs() in asm/process 203 # task_pt_regs() in asm/processor.h or asm/ptrace.h 253 # arch_has_single_step() if there is ha 204 # arch_has_single_step() if there is hardware single-step support 254 # arch_has_block_step() if there is ha 205 # arch_has_block_step() if there is hardware block-step support 255 # asm/syscall.h supplying asm- 206 # asm/syscall.h supplying asm-generic/syscall.h interface 256 # linux/regset.h user_regset in 207 # linux/regset.h user_regset interfaces 257 # CORE_DUMP_USE_REGSET #define'd in l 208 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h 258 # TIF_SYSCALL_TRACE calls ptrace_r !! 209 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 259 # TIF_NOTIFY_RESUME calls resume_u !! 210 # TIF_NOTIFY_RESUME calls tracehook_notify_resume() >> 211 # signal delivery calls tracehook_signal_handler() 260 # 212 # 261 config HAVE_ARCH_TRACEHOOK 213 config HAVE_ARCH_TRACEHOOK 262 bool 214 bool 263 215 264 config HAVE_DMA_CONTIGUOUS 216 config HAVE_DMA_CONTIGUOUS 265 bool 217 bool 266 218 267 config GENERIC_SMP_IDLE_THREAD 219 config GENERIC_SMP_IDLE_THREAD 268 bool 220 bool 269 221 270 config GENERIC_IDLE_POLL_SETUP 222 config GENERIC_IDLE_POLL_SETUP 271 bool 223 bool 272 224 273 config ARCH_HAS_FORTIFY_SOURCE 225 config ARCH_HAS_FORTIFY_SOURCE 274 bool 226 bool 275 help 227 help 276 An architecture should select this w 228 An architecture should select this when it can successfully 277 build and run with CONFIG_FORTIFY_SO 229 build and run with CONFIG_FORTIFY_SOURCE. 278 230 279 # 231 # 280 # Select if the arch provides a historic keepi 232 # Select if the arch provides a historic keepinit alias for the retain_initrd 281 # command line option 233 # command line option 282 # 234 # 283 config ARCH_HAS_KEEPINITRD 235 config ARCH_HAS_KEEPINITRD 284 bool 236 bool 285 237 286 # Select if arch has all set_memory_ro/rw/x/nx 238 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 287 config ARCH_HAS_SET_MEMORY 239 config ARCH_HAS_SET_MEMORY 288 bool 240 bool 289 241 290 # Select if arch has all set_direct_map_invali 242 # Select if arch has all set_direct_map_invalid/default() functions 291 config ARCH_HAS_SET_DIRECT_MAP 243 config ARCH_HAS_SET_DIRECT_MAP 292 bool 244 bool 293 245 294 # 246 # 295 # Select if the architecture provides the arch 247 # Select if the architecture provides the arch_dma_set_uncached symbol to 296 # either provide an uncached segment alias for 248 # either provide an uncached segment alias for a DMA allocation, or 297 # to remap the page tables in place. 249 # to remap the page tables in place. 298 # 250 # 299 config ARCH_HAS_DMA_SET_UNCACHED 251 config ARCH_HAS_DMA_SET_UNCACHED 300 bool 252 bool 301 253 302 # 254 # 303 # Select if the architectures provides the arc 255 # Select if the architectures provides the arch_dma_clear_uncached symbol 304 # to undo an in-place page table remap for unc 256 # to undo an in-place page table remap for uncached access. 305 # 257 # 306 config ARCH_HAS_DMA_CLEAR_UNCACHED 258 config ARCH_HAS_DMA_CLEAR_UNCACHED 307 bool 259 bool 308 260 309 config ARCH_HAS_CPU_FINALIZE_INIT !! 261 # Select if arch init_task must go in the __init_task_data section >> 262 config ARCH_TASK_STRUCT_ON_STACK 310 bool 263 bool 311 264 312 # The architecture has a per-task state that i !! 265 # Select if arch has its private alloc_task_struct() function 313 config ARCH_HAS_CPU_PASID !! 266 config ARCH_TASK_STRUCT_ALLOCATOR 314 bool 267 bool 315 select IOMMU_MM_DATA << 316 268 317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 269 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 318 bool 270 bool >> 271 depends on !ARCH_TASK_STRUCT_ALLOCATOR 319 help 272 help 320 An architecture should select this t 273 An architecture should select this to provide hardened usercopy 321 knowledge about what region of the t 274 knowledge about what region of the thread_struct should be 322 whitelisted for copying to userspace 275 whitelisted for copying to userspace. Normally this is only the 323 FPU registers. Specifically, arch_th 276 FPU registers. Specifically, arch_thread_struct_whitelist() 324 should be implemented. Without this, 277 should be implemented. Without this, the entire thread_struct 325 field in task_struct will be left wh 278 field in task_struct will be left whitelisted. 326 279 327 # Select if arch wants to size task_struct dyn !! 280 # Select if arch has its private alloc_thread_stack() function 328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 281 config ARCH_THREAD_STACK_ALLOCATOR 329 bool 282 bool 330 283 331 config ARCH_WANTS_NO_INSTR !! 284 # Select if arch wants to size task_struct dynamically via arch_task_struct_size: >> 285 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 332 bool 286 bool 333 help << 334 An architecture should select this i << 335 functions to denote that the toolcha << 336 functions and is required for correc << 337 287 338 config ARCH_32BIT_OFF_T 288 config ARCH_32BIT_OFF_T 339 bool 289 bool 340 depends on !64BIT 290 depends on !64BIT 341 help 291 help 342 All new 32-bit architectures should 292 All new 32-bit architectures should have 64-bit off_t type on 343 userspace side which corresponds to 293 userspace side which corresponds to the loff_t kernel type. This 344 is the requirement for modern ABIs. 294 is the requirement for modern ABIs. Some existing architectures 345 still support 32-bit off_t. This opt 295 still support 32-bit off_t. This option is enabled for all such 346 architectures explicitly. 296 architectures explicitly. 347 297 348 # Selected by 64 bit architectures which have 298 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 349 config ARCH_32BIT_USTAT_F_TINODE 299 config ARCH_32BIT_USTAT_F_TINODE 350 bool 300 bool 351 301 352 config HAVE_ASM_MODVERSIONS 302 config HAVE_ASM_MODVERSIONS 353 bool 303 bool 354 help 304 help 355 This symbol should be selected by an 305 This symbol should be selected by an architecture if it provides 356 <asm/asm-prototypes.h> to support th 306 <asm/asm-prototypes.h> to support the module versioning for symbols 357 exported from assembly code. 307 exported from assembly code. 358 308 359 config HAVE_REGS_AND_STACK_ACCESS_API 309 config HAVE_REGS_AND_STACK_ACCESS_API 360 bool 310 bool 361 help 311 help 362 This symbol should be selected by an 312 This symbol should be selected by an architecture if it supports 363 the API needed to access registers a 313 the API needed to access registers and stack entries from pt_regs, 364 declared in asm/ptrace.h 314 declared in asm/ptrace.h 365 For example the kprobes-based event 315 For example the kprobes-based event tracer needs this API. 366 316 367 config HAVE_RSEQ 317 config HAVE_RSEQ 368 bool 318 bool 369 depends on HAVE_REGS_AND_STACK_ACCESS_ 319 depends on HAVE_REGS_AND_STACK_ACCESS_API 370 help 320 help 371 This symbol should be selected by an 321 This symbol should be selected by an architecture if it 372 supports an implementation of restar 322 supports an implementation of restartable sequences. 373 323 374 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 324 config HAVE_FUNCTION_ARG_ACCESS_API 381 bool 325 bool 382 help 326 help 383 This symbol should be selected by an 327 This symbol should be selected by an architecture if it supports 384 the API needed to access function ar 328 the API needed to access function arguments from pt_regs, 385 declared in asm/ptrace.h 329 declared in asm/ptrace.h 386 330 387 config HAVE_HW_BREAKPOINT 331 config HAVE_HW_BREAKPOINT 388 bool 332 bool 389 depends on PERF_EVENTS 333 depends on PERF_EVENTS 390 334 391 config HAVE_MIXED_BREAKPOINTS_REGS 335 config HAVE_MIXED_BREAKPOINTS_REGS 392 bool 336 bool 393 depends on HAVE_HW_BREAKPOINT 337 depends on HAVE_HW_BREAKPOINT 394 help 338 help 395 Depending on the arch implementation 339 Depending on the arch implementation of hardware breakpoints, 396 some of them have separate registers 340 some of them have separate registers for data and instruction 397 breakpoints addresses, others have m 341 breakpoints addresses, others have mixed registers to store 398 them but define the access type in a 342 them but define the access type in a control register. 399 Select this option if your arch impl 343 Select this option if your arch implements breakpoints under the 400 latter fashion. 344 latter fashion. 401 345 402 config HAVE_USER_RETURN_NOTIFIER 346 config HAVE_USER_RETURN_NOTIFIER 403 bool 347 bool 404 348 405 config HAVE_PERF_EVENTS_NMI 349 config HAVE_PERF_EVENTS_NMI 406 bool 350 bool 407 help 351 help 408 System hardware can generate an NMI 352 System hardware can generate an NMI using the perf event 409 subsystem. Also has support for cal 353 subsystem. Also has support for calculating CPU cycle events 410 to determine how many clock cycles i 354 to determine how many clock cycles in a given period. 411 355 412 config HAVE_HARDLOCKUP_DETECTOR_PERF 356 config HAVE_HARDLOCKUP_DETECTOR_PERF 413 bool 357 bool 414 depends on HAVE_PERF_EVENTS_NMI 358 depends on HAVE_PERF_EVENTS_NMI 415 help 359 help 416 The arch chooses to use the generic 360 The arch chooses to use the generic perf-NMI-based hardlockup 417 detector. Must define HAVE_PERF_EVEN 361 detector. Must define HAVE_PERF_EVENTS_NMI. 418 362 419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 363 config HAVE_NMI_WATCHDOG >> 364 depends on HAVE_NMI 420 bool 365 bool 421 help 366 help 422 The arch provides its own hardlockup !! 367 The arch provides a low level NMI watchdog. It provides 423 of the generic ones. !! 368 asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 424 369 425 It uses the same command line parame !! 370 config HAVE_HARDLOCKUP_DETECTOR_ARCH 426 as the generic hardlockup detectors. !! 371 bool >> 372 select HAVE_NMI_WATCHDOG >> 373 help >> 374 The arch chooses to provide its own hardlockup detector, which is >> 375 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config >> 376 interfaces and parameters provided by hardlockup detector subsystem. 427 377 428 config HAVE_PERF_REGS 378 config HAVE_PERF_REGS 429 bool 379 bool 430 help 380 help 431 Support selective register dumps for 381 Support selective register dumps for perf events. This includes 432 bit-mapping of each registers and a 382 bit-mapping of each registers and a unique architecture id. 433 383 434 config HAVE_PERF_USER_STACK_DUMP 384 config HAVE_PERF_USER_STACK_DUMP 435 bool 385 bool 436 help 386 help 437 Support user stack dumps for perf ev 387 Support user stack dumps for perf event samples. This needs 438 access to the user stack pointer whi 388 access to the user stack pointer which is not unified across 439 architectures. 389 architectures. 440 390 441 config HAVE_ARCH_JUMP_LABEL 391 config HAVE_ARCH_JUMP_LABEL 442 bool 392 bool 443 393 444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 394 config HAVE_ARCH_JUMP_LABEL_RELATIVE 445 bool 395 bool 446 396 447 config MMU_GATHER_TABLE_FREE 397 config MMU_GATHER_TABLE_FREE 448 bool 398 bool 449 399 450 config MMU_GATHER_RCU_TABLE_FREE 400 config MMU_GATHER_RCU_TABLE_FREE 451 bool 401 bool 452 select MMU_GATHER_TABLE_FREE 402 select MMU_GATHER_TABLE_FREE 453 403 454 config MMU_GATHER_PAGE_SIZE 404 config MMU_GATHER_PAGE_SIZE 455 bool 405 bool 456 406 457 config MMU_GATHER_NO_RANGE 407 config MMU_GATHER_NO_RANGE 458 bool 408 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 << 466 409 467 config MMU_GATHER_NO_GATHER 410 config MMU_GATHER_NO_GATHER 468 bool 411 bool 469 depends on MMU_GATHER_TABLE_FREE 412 depends on MMU_GATHER_TABLE_FREE 470 413 471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 414 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 472 bool 415 bool 473 help 416 help 474 Temporary select until all architect 417 Temporary select until all architectures can be converted to have 475 irqs disabled over activate_mm. Arch 418 irqs disabled over activate_mm. Architectures that do IPI based TLB 476 shootdowns should enable this. 419 shootdowns should enable this. 477 420 478 # 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 421 config ARCH_HAVE_NMI_SAFE_CMPXCHG 511 bool 422 bool 512 423 513 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 424 config HAVE_ALIGNED_STRUCT_PAGE 526 bool 425 bool 527 help 426 help 528 This makes sure that struct pages ar 427 This makes sure that struct pages are double word aligned and that 529 e.g. the SLUB allocator can perform 428 e.g. the SLUB allocator can perform double word atomic operations 530 on a struct page for better performa 429 on a struct page for better performance. However selecting this 531 might increase the size of a struct 430 might increase the size of a struct page by a word. 532 431 533 config HAVE_CMPXCHG_LOCAL 432 config HAVE_CMPXCHG_LOCAL 534 bool 433 bool 535 434 536 config HAVE_CMPXCHG_DOUBLE 435 config HAVE_CMPXCHG_DOUBLE 537 bool 436 bool 538 437 539 config ARCH_WEAK_RELEASE_ACQUIRE 438 config ARCH_WEAK_RELEASE_ACQUIRE 540 bool 439 bool 541 440 542 config ARCH_WANT_IPC_PARSE_VERSION 441 config ARCH_WANT_IPC_PARSE_VERSION 543 bool 442 bool 544 443 545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 444 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 546 bool 445 bool 547 446 548 config ARCH_WANT_OLD_COMPAT_IPC 447 config ARCH_WANT_OLD_COMPAT_IPC 549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 448 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 550 bool 449 bool 551 450 552 config HAVE_ARCH_SECCOMP 451 config HAVE_ARCH_SECCOMP 553 bool 452 bool 554 help 453 help 555 An arch should select this symbol to 454 An arch should select this symbol to support seccomp mode 1 (the fixed 556 syscall policy), and must provide an 455 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 557 and compat syscalls if the asm-gener 456 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 558 - __NR_seccomp_read_32 457 - __NR_seccomp_read_32 559 - __NR_seccomp_write_32 458 - __NR_seccomp_write_32 560 - __NR_seccomp_exit_32 459 - __NR_seccomp_exit_32 561 - __NR_seccomp_sigreturn_32 460 - __NR_seccomp_sigreturn_32 562 461 563 config HAVE_ARCH_SECCOMP_FILTER 462 config HAVE_ARCH_SECCOMP_FILTER 564 bool 463 bool 565 select HAVE_ARCH_SECCOMP 464 select HAVE_ARCH_SECCOMP 566 help 465 help 567 An arch should select this symbol if 466 An arch should select this symbol if it provides all of these things: 568 - all the requirements for HAVE_ARCH 467 - all the requirements for HAVE_ARCH_SECCOMP 569 - syscall_get_arch() 468 - syscall_get_arch() 570 - syscall_get_arguments() 469 - syscall_get_arguments() 571 - syscall_rollback() 470 - syscall_rollback() 572 - syscall_set_return_value() 471 - syscall_set_return_value() 573 - SIGSYS siginfo_t support 472 - SIGSYS siginfo_t support 574 - secure_computing is called from a 473 - secure_computing is called from a ptrace_event()-safe context 575 - secure_computing return value is c 474 - secure_computing return value is checked and a return value of -1 576 results in the system call being s 475 results in the system call being skipped immediately. 577 - seccomp syscall wired up 476 - seccomp syscall wired up 578 - if !HAVE_SPARSE_SYSCALL_NR, have S 477 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 478 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 580 COMPAT is supported, have the SECC 479 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 581 480 582 config SECCOMP 481 config SECCOMP 583 prompt "Enable seccomp to safely execu 482 prompt "Enable seccomp to safely execute untrusted bytecode" 584 def_bool y 483 def_bool y 585 depends on HAVE_ARCH_SECCOMP 484 depends on HAVE_ARCH_SECCOMP 586 help 485 help 587 This kernel feature is useful for nu 486 This kernel feature is useful for number crunching applications 588 that may need to handle untrusted by 487 that may need to handle untrusted bytecode during their 589 execution. By using pipes or other t 488 execution. By using pipes or other transports made available 590 to the process as file descriptors s 489 to the process as file descriptors supporting the read/write 591 syscalls, it's possible to isolate t 490 syscalls, it's possible to isolate those applications in their 592 own address space using seccomp. Onc 491 own address space using seccomp. Once seccomp is enabled via 593 prctl(PR_SET_SECCOMP) or the seccomp 492 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 594 disabled and the task is only allowe 493 disabled and the task is only allowed to execute a few safe 595 syscalls defined by each seccomp mod 494 syscalls defined by each seccomp mode. 596 495 597 If unsure, say Y. 496 If unsure, say Y. 598 497 599 config SECCOMP_FILTER 498 config SECCOMP_FILTER 600 def_bool y 499 def_bool y 601 depends on HAVE_ARCH_SECCOMP_FILTER && 500 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 602 help 501 help 603 Enable tasks to build secure computi 502 Enable tasks to build secure computing environments defined 604 in terms of Berkeley Packet Filter p 503 in terms of Berkeley Packet Filter programs which implement 605 task-defined system call filtering p 504 task-defined system call filtering polices. 606 505 607 See Documentation/userspace-api/secc 506 See Documentation/userspace-api/seccomp_filter.rst for details. 608 507 609 config SECCOMP_CACHE_DEBUG 508 config SECCOMP_CACHE_DEBUG 610 bool "Show seccomp filter cache status 509 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 611 depends on SECCOMP_FILTER && !HAVE_SPA 510 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 612 depends on PROC_FS 511 depends on PROC_FS 613 help 512 help 614 This enables the /proc/pid/seccomp_c 513 This enables the /proc/pid/seccomp_cache interface to monitor 615 seccomp cache data. The file format 514 seccomp cache data. The file format is subject to change. Reading 616 the file requires CAP_SYS_ADMIN. 515 the file requires CAP_SYS_ADMIN. 617 516 618 This option is for debugging only. E 517 This option is for debugging only. Enabling presents the risk that 619 an adversary may be able to infer th 518 an adversary may be able to infer the seccomp filter logic. 620 519 621 If unsure, say N. 520 If unsure, say N. 622 521 623 config HAVE_ARCH_STACKLEAK 522 config HAVE_ARCH_STACKLEAK 624 bool 523 bool 625 help 524 help 626 An architecture should select this i 525 An architecture should select this if it has the code which 627 fills the used part of the kernel st 526 fills the used part of the kernel stack with the STACKLEAK_POISON 628 value before returning from system c 527 value before returning from system calls. 629 528 630 config HAVE_STACKPROTECTOR 529 config HAVE_STACKPROTECTOR 631 bool 530 bool 632 help 531 help 633 An arch should select this symbol if 532 An arch should select this symbol if: 634 - it has implemented a stack canary 533 - it has implemented a stack canary (e.g. __stack_chk_guard) 635 534 636 config STACKPROTECTOR 535 config STACKPROTECTOR 637 bool "Stack Protector buffer overflow 536 bool "Stack Protector buffer overflow detection" 638 depends on HAVE_STACKPROTECTOR 537 depends on HAVE_STACKPROTECTOR 639 depends on $(cc-option,-fstack-protect 538 depends on $(cc-option,-fstack-protector) 640 default y 539 default y 641 help 540 help 642 This option turns on the "stack-prot 541 This option turns on the "stack-protector" GCC feature. This 643 feature puts, at the beginning of fu 542 feature puts, at the beginning of functions, a canary value on 644 the stack just before the return add 543 the stack just before the return address, and validates 645 the value just before actually retur 544 the value just before actually returning. Stack based buffer 646 overflows (that need to overwrite th 545 overflows (that need to overwrite this return address) now also 647 overwrite the canary, which gets det 546 overwrite the canary, which gets detected and the attack is then 648 neutralized via a kernel panic. 547 neutralized via a kernel panic. 649 548 650 Functions will have the stack-protec 549 Functions will have the stack-protector canary logic added if they 651 have an 8-byte or larger character a 550 have an 8-byte or larger character array on the stack. 652 551 653 This feature requires gcc version 4. 552 This feature requires gcc version 4.2 or above, or a distribution 654 gcc with the feature backported ("-f 553 gcc with the feature backported ("-fstack-protector"). 655 554 656 On an x86 "defconfig" build, this fe 555 On an x86 "defconfig" build, this feature adds canary checks to 657 about 3% of all kernel functions, wh 556 about 3% of all kernel functions, which increases kernel code size 658 by about 0.3%. 557 by about 0.3%. 659 558 660 config STACKPROTECTOR_STRONG 559 config STACKPROTECTOR_STRONG 661 bool "Strong Stack Protector" 560 bool "Strong Stack Protector" 662 depends on STACKPROTECTOR 561 depends on STACKPROTECTOR 663 depends on $(cc-option,-fstack-protect 562 depends on $(cc-option,-fstack-protector-strong) 664 default y 563 default y 665 help 564 help 666 Functions will have the stack-protec 565 Functions will have the stack-protector canary logic added in any 667 of the following conditions: 566 of the following conditions: 668 567 669 - local variable's address used as p 568 - local variable's address used as part of the right hand side of an 670 assignment or function argument 569 assignment or function argument 671 - local variable is an array (or uni 570 - local variable is an array (or union containing an array), 672 regardless of array type or length 571 regardless of array type or length 673 - uses register local variables 572 - uses register local variables 674 573 675 This feature requires gcc version 4. 574 This feature requires gcc version 4.9 or above, or a distribution 676 gcc with the feature backported ("-f 575 gcc with the feature backported ("-fstack-protector-strong"). 677 576 678 On an x86 "defconfig" build, this fe 577 On an x86 "defconfig" build, this feature adds canary checks to 679 about 20% of all kernel functions, w 578 about 20% of all kernel functions, which increases the kernel code 680 size by about 2%. 579 size by about 2%. 681 580 682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 581 config ARCH_SUPPORTS_SHADOW_CALL_STACK 683 bool 582 bool 684 help 583 help 685 An architecture should select this i !! 584 An architecture should select this if it supports Clang's Shadow 686 Shadow Call Stack and implements run !! 585 Call Stack and implements runtime support for shadow stack 687 switching. 586 switching. 688 587 689 config SHADOW_CALL_STACK 588 config SHADOW_CALL_STACK 690 bool "Shadow Call Stack" !! 589 bool "Clang Shadow Call Stack" 691 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 590 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK 692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 591 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 693 depends on MMU !! 592 help 694 help !! 593 This option enables Clang's Shadow Call Stack, which uses a 695 This option enables the compiler's S !! 594 shadow stack to protect function return addresses from being 696 uses a shadow stack to protect funct !! 595 overwritten by an attacker. More information can be found in 697 being overwritten by an attacker. Mo !! 596 Clang's documentation: 698 in the compiler's documentation: << 699 597 700 - Clang: https://clang.llvm.org/docs !! 598 https://clang.llvm.org/docs/ShadowCallStack.html 701 - GCC: https://gcc.gnu.org/onlinedoc << 702 599 703 Note that security guarantees in the 600 Note that security guarantees in the kernel differ from the 704 ones documented for user space. The 601 ones documented for user space. The kernel must store addresses 705 of shadow stacks in memory, which me 602 of shadow stacks in memory, which means an attacker capable of 706 reading and writing arbitrary memory 603 reading and writing arbitrary memory may be able to locate them 707 and hijack control flow by modifying 604 and hijack control flow by modifying the stacks. 708 605 709 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 606 config LTO 717 bool 607 bool 718 help 608 help 719 Selected if the kernel will be built 609 Selected if the kernel will be built using the compiler's LTO feature. 720 610 721 config LTO_CLANG 611 config LTO_CLANG 722 bool 612 bool 723 select LTO 613 select LTO 724 help 614 help 725 Selected if the kernel will be built 615 Selected if the kernel will be built using Clang's LTO feature. 726 616 727 config ARCH_SUPPORTS_LTO_CLANG 617 config ARCH_SUPPORTS_LTO_CLANG 728 bool 618 bool 729 help 619 help 730 An architecture should select this o 620 An architecture should select this option if it supports: 731 - compiling with Clang, 621 - compiling with Clang, 732 - compiling inline assembly with Cla 622 - compiling inline assembly with Clang's integrated assembler, 733 - and linking with LLD. 623 - and linking with LLD. 734 624 735 config ARCH_SUPPORTS_LTO_CLANG_THIN 625 config ARCH_SUPPORTS_LTO_CLANG_THIN 736 bool 626 bool 737 help 627 help 738 An architecture should select this o 628 An architecture should select this option if it can support Clang's 739 ThinLTO mode. 629 ThinLTO mode. 740 630 741 config HAS_LTO_CLANG 631 config HAS_LTO_CLANG 742 def_bool y 632 def_bool y 743 depends on CC_IS_CLANG && LD_IS_LLD && !! 633 # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510 >> 634 depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM 744 depends on $(success,$(NM) --help | he 635 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 745 depends on $(success,$(AR) --help | he 636 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 746 depends on ARCH_SUPPORTS_LTO_CLANG 637 depends on ARCH_SUPPORTS_LTO_CLANG 747 depends on !FTRACE_MCOUNT_USE_RECORDMC 638 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 748 # https://github.com/ClangBuiltLinux/l !! 639 depends on !KASAN || KASAN_HW_TAGS 749 depends on (!KASAN || KASAN_HW_TAGS || << 750 depends on (!KCOV || CLANG_VERSION >= << 751 depends on !GCOV_KERNEL 640 depends on !GCOV_KERNEL 752 help 641 help 753 The compiler and Kconfig options sup 642 The compiler and Kconfig options support building with Clang's 754 LTO. 643 LTO. 755 644 756 choice 645 choice 757 prompt "Link Time Optimization (LTO)" 646 prompt "Link Time Optimization (LTO)" 758 default LTO_NONE 647 default LTO_NONE 759 help 648 help 760 This option enables Link Time Optimi 649 This option enables Link Time Optimization (LTO), which allows the 761 compiler to optimize binaries global 650 compiler to optimize binaries globally. 762 651 763 If unsure, select LTO_NONE. Note tha 652 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 764 so it's disabled by default. 653 so it's disabled by default. 765 654 766 config LTO_NONE 655 config LTO_NONE 767 bool "None" 656 bool "None" 768 help 657 help 769 Build the kernel normally, without L 658 Build the kernel normally, without Link Time Optimization (LTO). 770 659 771 config LTO_CLANG_FULL 660 config LTO_CLANG_FULL 772 bool "Clang Full LTO (EXPERIMENTAL)" 661 bool "Clang Full LTO (EXPERIMENTAL)" 773 depends on HAS_LTO_CLANG 662 depends on HAS_LTO_CLANG 774 depends on !COMPILE_TEST 663 depends on !COMPILE_TEST 775 select LTO_CLANG 664 select LTO_CLANG 776 help 665 help 777 This option enables Clang's full Lin !! 666 This option enables Clang's full Link Time Optimization (LTO), which 778 allows the compiler to optimize the !! 667 allows the compiler to optimize the kernel globally. If you enable 779 this option, the compiler generates !! 668 this option, the compiler generates LLVM bitcode instead of ELF 780 object files, and the actual compila !! 669 object files, and the actual compilation from bitcode happens at 781 the LTO link step, which may take se !! 670 the LTO link step, which may take several minutes depending on the 782 kernel configuration. More informati !! 671 kernel configuration. More information can be found from LLVM's 783 documentation: !! 672 documentation: 784 673 785 https://llvm.org/docs/LinkTimeOpti 674 https://llvm.org/docs/LinkTimeOptimization.html 786 675 787 During link time, this option can us 676 During link time, this option can use a large amount of RAM, and 788 may take much longer than the ThinLT 677 may take much longer than the ThinLTO option. 789 678 790 config LTO_CLANG_THIN 679 config LTO_CLANG_THIN 791 bool "Clang ThinLTO (EXPERIMENTAL)" 680 bool "Clang ThinLTO (EXPERIMENTAL)" 792 depends on HAS_LTO_CLANG && ARCH_SUPPO 681 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 793 select LTO_CLANG 682 select LTO_CLANG 794 help 683 help 795 This option enables Clang's ThinLTO, 684 This option enables Clang's ThinLTO, which allows for parallel 796 optimization and faster incremental 685 optimization and faster incremental compiles compared to the 797 CONFIG_LTO_CLANG_FULL option. More i 686 CONFIG_LTO_CLANG_FULL option. More information can be found 798 from Clang's documentation: 687 from Clang's documentation: 799 688 800 https://clang.llvm.org/docs/ThinLT 689 https://clang.llvm.org/docs/ThinLTO.html 801 690 802 If unsure, say Y. 691 If unsure, say Y. 803 endchoice 692 endchoice 804 693 805 config ARCH_SUPPORTS_CFI_CLANG 694 config ARCH_SUPPORTS_CFI_CLANG 806 bool 695 bool 807 help 696 help 808 An architecture should select this o 697 An architecture should select this option if it can support Clang's 809 Control-Flow Integrity (CFI) checkin 698 Control-Flow Integrity (CFI) checking. 810 699 811 config ARCH_USES_CFI_TRAPS << 812 bool << 813 << 814 config CFI_CLANG 700 config CFI_CLANG 815 bool "Use Clang's Control Flow Integri 701 bool "Use Clang's Control Flow Integrity (CFI)" 816 depends on ARCH_SUPPORTS_CFI_CLANG !! 702 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG 817 depends on $(cc-option,-fsanitize=kcfi !! 703 # Clang >= 12: >> 704 # - https://bugs.llvm.org/show_bug.cgi?id=46258 >> 705 # - https://bugs.llvm.org/show_bug.cgi?id=47479 >> 706 depends on CLANG_VERSION >= 120000 >> 707 select KALLSYMS 818 help 708 help 819 This option enables Clang's forward- !! 709 This option enables Clang’s forward-edge Control Flow Integrity 820 (CFI) checking, where the compiler i 710 (CFI) checking, where the compiler injects a runtime check to each 821 indirect function call to ensure the 711 indirect function call to ensure the target is a valid function with 822 the correct static type. This restri 712 the correct static type. This restricts possible call targets and 823 makes it more difficult for an attac 713 makes it more difficult for an attacker to exploit bugs that allow 824 the modification of stored function 714 the modification of stored function pointers. More information can be 825 found from Clang's documentation: 715 found from Clang's documentation: 826 716 827 https://clang.llvm.org/docs/Contro 717 https://clang.llvm.org/docs/ControlFlowIntegrity.html 828 718 >> 719 config CFI_CLANG_SHADOW >> 720 bool "Use CFI shadow to speed up cross-module checks" >> 721 default y >> 722 depends on CFI_CLANG && MODULES >> 723 help >> 724 If you select this option, the kernel builds a fast look-up table of >> 725 CFI check functions in loaded modules to reduce performance overhead. >> 726 >> 727 If unsure, say Y. >> 728 829 config CFI_PERMISSIVE 729 config CFI_PERMISSIVE 830 bool "Use CFI in permissive mode" 730 bool "Use CFI in permissive mode" 831 depends on CFI_CLANG 731 depends on CFI_CLANG 832 help 732 help 833 When selected, Control Flow Integrit 733 When selected, Control Flow Integrity (CFI) violations result in a 834 warning instead of a kernel panic. T 734 warning instead of a kernel panic. This option should only be used 835 for finding indirect call type misma 735 for finding indirect call type mismatches during development. 836 736 837 If unsure, say N. 737 If unsure, say N. 838 738 839 config HAVE_ARCH_WITHIN_STACK_FRAMES 739 config HAVE_ARCH_WITHIN_STACK_FRAMES 840 bool 740 bool 841 help 741 help 842 An architecture should select this i 742 An architecture should select this if it can walk the kernel stack 843 frames to determine if an object is 743 frames to determine if an object is part of either the arguments 844 or local variables (i.e. that it exc 744 or local variables (i.e. that it excludes saved return addresses, 845 and similar) by implementing an inli 745 and similar) by implementing an inline arch_within_stack_frames(), 846 which is used by CONFIG_HARDENED_USE 746 which is used by CONFIG_HARDENED_USERCOPY. 847 747 848 config HAVE_CONTEXT_TRACKING_USER !! 748 config HAVE_CONTEXT_TRACKING 849 bool 749 bool 850 help 750 help 851 Provide kernel/user boundaries probe 751 Provide kernel/user boundaries probes necessary for subsystems 852 that need it, such as userspace RCU 752 that need it, such as userspace RCU extended quiescent state. 853 Syscalls need to be wrapped inside u 753 Syscalls need to be wrapped inside user_exit()-user_enter(), either 854 optimized behind static key or throu 754 optimized behind static key or through the slow path using TIF_NOHZ 855 flag. Exceptions handlers must be wr 755 flag. Exceptions handlers must be wrapped as well. Irqs are already 856 protected inside ct_irq_enter/ct_irq !! 756 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal 857 handling on irq exit still need to b 757 handling on irq exit still need to be protected. 858 758 859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 759 config HAVE_CONTEXT_TRACKING_OFFSTACK 860 bool 760 bool 861 help 761 help 862 Architecture neither relies on excep 762 Architecture neither relies on exception_enter()/exception_exit() 863 nor on schedule_user(). Also preempt 763 nor on schedule_user(). Also preempt_schedule_notrace() and 864 preempt_schedule_irq() can't be call 764 preempt_schedule_irq() can't be called in a preemptible section 865 while context tracking is CONTEXT_US 765 while context tracking is CONTEXT_USER. This feature reflects a sane 866 entry implementation where the follo 766 entry implementation where the following requirements are met on 867 critical entry code, ie: before user 767 critical entry code, ie: before user_exit() or after user_enter(): 868 768 869 - Critical entry code isn't preempti 769 - Critical entry code isn't preemptible (or better yet: 870 not interruptible). 770 not interruptible). 871 - No use of RCU read side critical s !! 771 - No use of RCU read side critical sections, unless rcu_nmi_enter() 872 got called. 772 got called. 873 - No use of instrumentation, unless 773 - No use of instrumentation, unless instrumentation_begin() got 874 called. 774 called. 875 775 876 config HAVE_TIF_NOHZ 776 config HAVE_TIF_NOHZ 877 bool 777 bool 878 help 778 help 879 Arch relies on TIF_NOHZ and syscall 779 Arch relies on TIF_NOHZ and syscall slow path to implement context 880 tracking calls to user_enter()/user_ 780 tracking calls to user_enter()/user_exit(). 881 781 882 config HAVE_VIRT_CPU_ACCOUNTING 782 config HAVE_VIRT_CPU_ACCOUNTING 883 bool 783 bool 884 784 885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 785 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 886 bool 786 bool 887 help 787 help 888 Architecture has its own way to acco 788 Architecture has its own way to account idle CPU time and therefore 889 doesn't implement vtime_account_idle 789 doesn't implement vtime_account_idle(). 890 790 891 config ARCH_HAS_SCALED_CPUTIME 791 config ARCH_HAS_SCALED_CPUTIME 892 bool 792 bool 893 793 894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 794 config HAVE_VIRT_CPU_ACCOUNTING_GEN 895 bool 795 bool 896 default y if 64BIT 796 default y if 64BIT 897 help 797 help 898 With VIRT_CPU_ACCOUNTING_GEN, cputim 798 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 899 Before enabling this option, arch co 799 Before enabling this option, arch code must be audited 900 to ensure there are no races in conc 800 to ensure there are no races in concurrent read/write of 901 cputime_t. For example, reading/writ 801 cputime_t. For example, reading/writing 64-bit cputime_t on 902 some 32-bit arches may require multi 802 some 32-bit arches may require multiple accesses, so proper 903 locking is needed to protect against 803 locking is needed to protect against concurrent accesses. 904 804 905 config HAVE_IRQ_TIME_ACCOUNTING 805 config HAVE_IRQ_TIME_ACCOUNTING 906 bool 806 bool 907 help 807 help 908 Archs need to ensure they use a high 808 Archs need to ensure they use a high enough resolution clock to 909 support irq time accounting and then 809 support irq time accounting and then call enable_sched_clock_irqtime(). 910 810 911 config HAVE_MOVE_PUD 811 config HAVE_MOVE_PUD 912 bool 812 bool 913 help 813 help 914 Architectures that select this are a 814 Architectures that select this are able to move page tables at the 915 PUD level. If there are only 3 page 815 PUD level. If there are only 3 page table levels, the move effectively 916 happens at the PGD level. 816 happens at the PGD level. 917 817 918 config HAVE_MOVE_PMD 818 config HAVE_MOVE_PMD 919 bool 819 bool 920 help 820 help 921 Archs that select this are able to m 821 Archs that select this are able to move page tables at the PMD level. 922 822 923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 823 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 924 bool 824 bool 925 825 926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 826 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 927 bool 827 bool 928 828 929 config HAVE_ARCH_HUGE_VMAP 829 config HAVE_ARCH_HUGE_VMAP 930 bool 830 bool 931 831 932 # 832 # 933 # Archs that select this would be capable of 833 # Archs that select this would be capable of PMD-sized vmaps (i.e., 934 # arch_vmap_pmd_supported() returns true). Th !! 834 # arch_vmap_pmd_supported() returns true), and they must make no assumptions 935 # must be used to enable allocations to use h !! 835 # that vmalloc memory is mapped with PAGE_SIZE ptes. The VM_NO_HUGE_VMAP flag >> 836 # can be used to prohibit arch-specific allocations from using hugepages to >> 837 # help with this (e.g., modules may require it). 936 # 838 # 937 config HAVE_ARCH_HUGE_VMALLOC 839 config HAVE_ARCH_HUGE_VMALLOC 938 depends on HAVE_ARCH_HUGE_VMAP 840 depends on HAVE_ARCH_HUGE_VMAP 939 bool 841 bool 940 842 941 config ARCH_WANT_HUGE_PMD_SHARE 843 config ARCH_WANT_HUGE_PMD_SHARE 942 bool 844 bool 943 845 944 # 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 846 config HAVE_ARCH_SOFT_DIRTY 953 bool 847 bool 954 848 955 config HAVE_MOD_ARCH_SPECIFIC 849 config HAVE_MOD_ARCH_SPECIFIC 956 bool 850 bool 957 help 851 help 958 The arch uses struct mod_arch_specif 852 The arch uses struct mod_arch_specific to store data. Many arches 959 just need a simple module loader wit 853 just need a simple module loader without arch specific data - those 960 should not enable this. 854 should not enable this. 961 855 962 config MODULES_USE_ELF_RELA 856 config MODULES_USE_ELF_RELA 963 bool 857 bool 964 help 858 help 965 Modules only use ELF RELA relocation 859 Modules only use ELF RELA relocations. Modules with ELF REL 966 relocations will give an error. 860 relocations will give an error. 967 861 968 config MODULES_USE_ELF_REL 862 config MODULES_USE_ELF_REL 969 bool 863 bool 970 help 864 help 971 Modules only use ELF REL relocations 865 Modules only use ELF REL relocations. Modules with ELF RELA 972 relocations will give an error. 866 relocations will give an error. 973 867 974 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 868 config HAVE_IRQ_EXIT_ON_IRQ_STACK 989 bool 869 bool 990 help 870 help 991 Architecture doesn't only execute th 871 Architecture doesn't only execute the irq handler on the irq stack 992 but also irq_exit(). This way we can 872 but also irq_exit(). This way we can process softirqs on this irq 993 stack instead of switching to a new 873 stack instead of switching to a new one when we call __do_softirq() 994 in the end of an hardirq. 874 in the end of an hardirq. 995 This spares a stack switch and impro 875 This spares a stack switch and improves cache usage on softirq 996 processing. 876 processing. 997 877 998 config HAVE_SOFTIRQ_ON_OWN_STACK 878 config HAVE_SOFTIRQ_ON_OWN_STACK 999 bool 879 bool 1000 help 880 help 1001 Architecture provides a function to 881 Architecture provides a function to run __do_softirq() on a 1002 separate stack. !! 882 seperate 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 883 1014 config PGTABLE_LEVELS 884 config PGTABLE_LEVELS 1015 int 885 int 1016 default 2 886 default 2 1017 887 1018 config ARCH_HAS_ELF_RANDOMIZE 888 config ARCH_HAS_ELF_RANDOMIZE 1019 bool 889 bool 1020 help 890 help 1021 An architecture supports choosing r 891 An architecture supports choosing randomized locations for 1022 stack, mmap, brk, and ET_DYN. Defin 892 stack, mmap, brk, and ET_DYN. Defined functions: 1023 - arch_mmap_rnd() 893 - arch_mmap_rnd() 1024 - arch_randomize_brk() 894 - arch_randomize_brk() 1025 895 1026 config HAVE_ARCH_MMAP_RND_BITS 896 config HAVE_ARCH_MMAP_RND_BITS 1027 bool 897 bool 1028 help 898 help 1029 An arch should select this symbol i 899 An arch should select this symbol if it supports setting a variable 1030 number of bits for use in establish 900 number of bits for use in establishing the base address for mmap 1031 allocations, has MMU enabled and pr 901 allocations, has MMU enabled and provides values for both: 1032 - ARCH_MMAP_RND_BITS_MIN 902 - ARCH_MMAP_RND_BITS_MIN 1033 - ARCH_MMAP_RND_BITS_MAX 903 - ARCH_MMAP_RND_BITS_MAX 1034 904 1035 config HAVE_EXIT_THREAD 905 config HAVE_EXIT_THREAD 1036 bool 906 bool 1037 help 907 help 1038 An architecture implements exit_thr 908 An architecture implements exit_thread. 1039 909 1040 config ARCH_MMAP_RND_BITS_MIN 910 config ARCH_MMAP_RND_BITS_MIN 1041 int 911 int 1042 912 1043 config ARCH_MMAP_RND_BITS_MAX 913 config ARCH_MMAP_RND_BITS_MAX 1044 int 914 int 1045 915 1046 config ARCH_MMAP_RND_BITS_DEFAULT 916 config ARCH_MMAP_RND_BITS_DEFAULT 1047 int 917 int 1048 918 1049 config ARCH_MMAP_RND_BITS 919 config ARCH_MMAP_RND_BITS 1050 int "Number of bits to use for ASLR o 920 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 921 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1052 default ARCH_MMAP_RND_BITS_DEFAULT if 922 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1053 default ARCH_MMAP_RND_BITS_MIN 923 default ARCH_MMAP_RND_BITS_MIN 1054 depends on HAVE_ARCH_MMAP_RND_BITS 924 depends on HAVE_ARCH_MMAP_RND_BITS 1055 help 925 help 1056 This value can be used to select th 926 This value can be used to select the number of bits to use to 1057 determine the random offset to the 927 determine the random offset to the base address of vma regions 1058 resulting from mmap allocations. Th 928 resulting from mmap allocations. This value will be bounded 1059 by the architecture's minimum and m 929 by the architecture's minimum and maximum supported values. 1060 930 1061 This value can be changed after boo 931 This value can be changed after boot using the 1062 /proc/sys/vm/mmap_rnd_bits tunable 932 /proc/sys/vm/mmap_rnd_bits tunable 1063 933 1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 934 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1065 bool 935 bool 1066 help 936 help 1067 An arch should select this symbol i 937 An arch should select this symbol if it supports running applications 1068 in compatibility mode, supports set 938 in compatibility mode, supports setting a variable number of bits for 1069 use in establishing the base addres 939 use in establishing the base address for mmap allocations, has MMU 1070 enabled and provides values for bot 940 enabled and provides values for both: 1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 941 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 942 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1073 943 1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 944 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1075 int 945 int 1076 946 1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 947 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1078 int 948 int 1079 949 1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 950 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1081 int 951 int 1082 952 1083 config ARCH_MMAP_RND_COMPAT_BITS 953 config ARCH_MMAP_RND_COMPAT_BITS 1084 int "Number of bits to use for ASLR o 954 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 955 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 956 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 957 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 958 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1089 help 959 help 1090 This value can be used to select th 960 This value can be used to select the number of bits to use to 1091 determine the random offset to the 961 determine the random offset to the base address of vma regions 1092 resulting from mmap allocations for 962 resulting from mmap allocations for compatible applications This 1093 value will be bounded by the archit 963 value will be bounded by the architecture's minimum and maximum 1094 supported values. 964 supported values. 1095 965 1096 This value can be changed after boo 966 This value can be changed after boot using the 1097 /proc/sys/vm/mmap_rnd_compat_bits t 967 /proc/sys/vm/mmap_rnd_compat_bits tunable 1098 968 1099 config HAVE_ARCH_COMPAT_MMAP_BASES 969 config HAVE_ARCH_COMPAT_MMAP_BASES 1100 bool 970 bool 1101 help 971 help 1102 This allows 64bit applications to i 972 This allows 64bit applications to invoke 32-bit mmap() syscall 1103 and vice-versa 32-bit applications 973 and vice-versa 32-bit applications to call 64-bit mmap(). 1104 Required for applications doing dif 974 Required for applications doing different bitness syscalls. 1105 975 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 976 # This allows to use a set of generic functions to determine mmap base 1208 # address by giving priority to top-down sche 977 # address by giving priority to top-down scheme only if the process 1209 # is not in legacy mode (compat task, unlimit 978 # is not in legacy mode (compat task, unlimited stack size or 1210 # sysctl_legacy_va_layout). 979 # sysctl_legacy_va_layout). 1211 # Architecture that selects this option can p 980 # Architecture that selects this option can provide its own version of: 1212 # - STACK_RND_MASK 981 # - STACK_RND_MASK 1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 982 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1214 bool 983 bool 1215 depends on MMU 984 depends on MMU 1216 select ARCH_HAS_ELF_RANDOMIZE 985 select ARCH_HAS_ELF_RANDOMIZE 1217 986 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 987 config HAVE_STACK_VALIDATION 1235 bool 988 bool 1236 help 989 help 1237 Architecture supports objtool compi !! 990 Architecture supports the 'objtool check' host tool command, which 1238 validation. !! 991 performs compile-time stack metadata validation. 1239 992 1240 config HAVE_RELIABLE_STACKTRACE 993 config HAVE_RELIABLE_STACKTRACE 1241 bool 994 bool 1242 help 995 help 1243 Architecture has either save_stack_ 996 Architecture has either save_stack_trace_tsk_reliable() or 1244 arch_stack_walk_reliable() function 997 arch_stack_walk_reliable() function which only returns a stack trace 1245 if it can guarantee the trace is re 998 if it can guarantee the trace is reliable. 1246 999 1247 config HAVE_ARCH_HASH 1000 config HAVE_ARCH_HASH 1248 bool 1001 bool 1249 default n 1002 default n 1250 help 1003 help 1251 If this is set, the architecture pr 1004 If this is set, the architecture provides an <asm/hash.h> 1252 file which provides platform-specif 1005 file which provides platform-specific implementations of some 1253 functions in <linux/hash.h> or fs/n 1006 functions in <linux/hash.h> or fs/namei.c. 1254 1007 1255 config HAVE_ARCH_NVRAM_OPS 1008 config HAVE_ARCH_NVRAM_OPS 1256 bool 1009 bool 1257 1010 1258 config ISA_BUS_API 1011 config ISA_BUS_API 1259 def_bool ISA 1012 def_bool ISA 1260 1013 1261 # 1014 # 1262 # ABI hall of shame 1015 # ABI hall of shame 1263 # 1016 # 1264 config CLONE_BACKWARDS 1017 config CLONE_BACKWARDS 1265 bool 1018 bool 1266 help 1019 help 1267 Architecture has tls passed as the 1020 Architecture has tls passed as the 4th argument of clone(2), 1268 not the 5th one. 1021 not the 5th one. 1269 1022 1270 config CLONE_BACKWARDS2 1023 config CLONE_BACKWARDS2 1271 bool 1024 bool 1272 help 1025 help 1273 Architecture has the first two argu 1026 Architecture has the first two arguments of clone(2) swapped. 1274 1027 1275 config CLONE_BACKWARDS3 1028 config CLONE_BACKWARDS3 1276 bool 1029 bool 1277 help 1030 help 1278 Architecture has tls passed as the 1031 Architecture has tls passed as the 3rd argument of clone(2), 1279 not the 5th one. 1032 not the 5th one. 1280 1033 1281 config ODD_RT_SIGACTION 1034 config ODD_RT_SIGACTION 1282 bool 1035 bool 1283 help 1036 help 1284 Architecture has unusual rt_sigacti 1037 Architecture has unusual rt_sigaction(2) arguments 1285 1038 1286 config OLD_SIGSUSPEND 1039 config OLD_SIGSUSPEND 1287 bool 1040 bool 1288 help 1041 help 1289 Architecture has old sigsuspend(2) 1042 Architecture has old sigsuspend(2) syscall, of one-argument variety 1290 1043 1291 config OLD_SIGSUSPEND3 1044 config OLD_SIGSUSPEND3 1292 bool 1045 bool 1293 help 1046 help 1294 Even weirder antique ABI - three-ar 1047 Even weirder antique ABI - three-argument sigsuspend(2) 1295 1048 1296 config OLD_SIGACTION 1049 config OLD_SIGACTION 1297 bool 1050 bool 1298 help 1051 help 1299 Architecture has old sigaction(2) s 1052 Architecture has old sigaction(2) syscall. Nope, not the same 1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1053 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1301 but fairly different variant of sig 1054 but fairly different variant of sigaction(2), thanks to OSF/1 1302 compatibility... 1055 compatibility... 1303 1056 1304 config COMPAT_OLD_SIGACTION 1057 config COMPAT_OLD_SIGACTION 1305 bool 1058 bool 1306 1059 1307 config COMPAT_32BIT_TIME 1060 config COMPAT_32BIT_TIME 1308 bool "Provide system calls for 32-bit 1061 bool "Provide system calls for 32-bit time_t" 1309 default !64BIT || COMPAT 1062 default !64BIT || COMPAT 1310 help 1063 help 1311 This enables 32 bit time_t support 1064 This enables 32 bit time_t support in addition to 64 bit time_t support. 1312 This is relevant on all 32-bit arch 1065 This is relevant on all 32-bit architectures, and 64-bit architectures 1313 as part of compat syscall handling. 1066 as part of compat syscall handling. 1314 1067 1315 config ARCH_NO_PREEMPT 1068 config ARCH_NO_PREEMPT 1316 bool 1069 bool 1317 1070 >> 1071 config ARCH_EPHEMERAL_INODES >> 1072 def_bool n >> 1073 help >> 1074 An arch should select this symbol if it doesn't keep track of inode >> 1075 instances on its own, but instead relies on something else (e.g. the >> 1076 host kernel for an UML kernel). >> 1077 1318 config ARCH_SUPPORTS_RT 1078 config ARCH_SUPPORTS_RT 1319 bool 1079 bool 1320 1080 1321 config CPU_NO_EFFICIENT_FFS 1081 config CPU_NO_EFFICIENT_FFS 1322 def_bool n 1082 def_bool n 1323 1083 1324 config HAVE_ARCH_VMAP_STACK 1084 config HAVE_ARCH_VMAP_STACK 1325 def_bool n 1085 def_bool n 1326 help 1086 help 1327 An arch should select this symbol i 1087 An arch should select this symbol if it can support kernel stacks 1328 in vmalloc space. This means: 1088 in vmalloc space. This means: 1329 1089 1330 - vmalloc space must be large enoug 1090 - vmalloc space must be large enough to hold many kernel stacks. 1331 This may rule out many 32-bit arc 1091 This may rule out many 32-bit architectures. 1332 1092 1333 - Stacks in vmalloc space need to w 1093 - Stacks in vmalloc space need to work reliably. For example, if 1334 vmap page tables are created on d 1094 vmap page tables are created on demand, either this mechanism 1335 needs to work while the stack poi 1095 needs to work while the stack points to a virtual address with 1336 unpopulated page tables or arch c 1096 unpopulated page tables or arch code (switch_to() and switch_mm(), 1337 most likely) needs to ensure that 1097 most likely) needs to ensure that the stack's page table entries 1338 are populated before running on a 1098 are populated before running on a possibly unpopulated stack. 1339 1099 1340 - If the stack overflows into a gua 1100 - If the stack overflows into a guard page, something reasonable 1341 should happen. The definition of 1101 should happen. The definition of "reasonable" is flexible, but 1342 instantly rebooting without loggi 1102 instantly rebooting without logging anything would be unfriendly. 1343 1103 1344 config VMAP_STACK 1104 config VMAP_STACK 1345 default y 1105 default y 1346 bool "Use a virtually-mapped stack" 1106 bool "Use a virtually-mapped stack" 1347 depends on HAVE_ARCH_VMAP_STACK 1107 depends on HAVE_ARCH_VMAP_STACK 1348 depends on !KASAN || KASAN_HW_TAGS || 1108 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1349 help 1109 help 1350 Enable this if you want the use vir 1110 Enable this if you want the use virtually-mapped kernel stacks 1351 with guard pages. This causes kern 1111 with guard pages. This causes kernel stack overflows to be 1352 caught immediately rather than caus 1112 caught immediately rather than causing difficult-to-diagnose 1353 corruption. 1113 corruption. 1354 1114 1355 To use this with software KASAN mod 1115 To use this with software KASAN modes, the architecture must support 1356 backing virtual mappings with real 1116 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1357 must be enabled. 1117 must be enabled. 1358 1118 1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1119 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1360 def_bool n 1120 def_bool n 1361 help 1121 help 1362 An arch should select this symbol i 1122 An arch should select this symbol if it can support kernel stack 1363 offset randomization with calls to 1123 offset randomization with calls to add_random_kstack_offset() 1364 during syscall entry and choose_ran 1124 during syscall entry and choose_random_kstack_offset() during 1365 syscall exit. Careful removal of -f 1125 syscall exit. Careful removal of -fstack-protector-strong and 1366 -fstack-protector should also be ap 1126 -fstack-protector should also be applied to the entry code and 1367 closely examined, as the artificial 1127 closely examined, as the artificial stack bump looks like an array 1368 to the compiler, so it will attempt 1128 to the compiler, so it will attempt to add canary checks regardless 1369 of the static branch state. 1129 of the static branch state. 1370 1130 1371 config RANDOMIZE_KSTACK_OFFSET !! 1131 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1372 bool "Support for randomizing kernel !! 1132 bool "Randomize kernel stack offset on syscall entry" 1373 default y << 1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1133 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1375 depends on INIT_STACK_NONE || !CC_IS_ << 1376 help 1134 help 1377 The kernel stack offset can be rand 1135 The kernel stack offset can be randomized (after pt_regs) by 1378 roughly 5 bits of entropy, frustrat 1136 roughly 5 bits of entropy, frustrating memory corruption 1379 attacks that depend on stack addres 1137 attacks that depend on stack address determinism or 1380 cross-syscall address exposures. !! 1138 cross-syscall address exposures. This feature is controlled 1381 !! 1139 by kernel boot param "randomize_kstack_offset=on/off", and this 1382 The feature is controlled via the " !! 1140 config chooses the default boot state. 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 1141 1396 config ARCH_OPTIONAL_KERNEL_RWX 1142 config ARCH_OPTIONAL_KERNEL_RWX 1397 def_bool n 1143 def_bool n 1398 1144 1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1145 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1400 def_bool n 1146 def_bool n 1401 1147 1402 config ARCH_HAS_STRICT_KERNEL_RWX 1148 config ARCH_HAS_STRICT_KERNEL_RWX 1403 def_bool n 1149 def_bool n 1404 1150 1405 config STRICT_KERNEL_RWX 1151 config STRICT_KERNEL_RWX 1406 bool "Make kernel text and rodata rea 1152 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1153 depends on ARCH_HAS_STRICT_KERNEL_RWX 1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1154 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1409 help 1155 help 1410 If this is set, kernel text and rod 1156 If this is set, kernel text and rodata memory will be made read-only, 1411 and non-text memory will be made no 1157 and non-text memory will be made non-executable. This provides 1412 protection against certain security 1158 protection against certain security exploits (e.g. executing the heap 1413 or modifying text) 1159 or modifying text) 1414 1160 1415 These features are considered stand 1161 These features are considered standard security practice these days. 1416 You should say Y here in almost all 1162 You should say Y here in almost all cases. 1417 1163 1418 config ARCH_HAS_STRICT_MODULE_RWX 1164 config ARCH_HAS_STRICT_MODULE_RWX 1419 def_bool n 1165 def_bool n 1420 1166 1421 config STRICT_MODULE_RWX 1167 config STRICT_MODULE_RWX 1422 bool "Set loadable kernel module data 1168 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 1169 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1170 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1425 help 1171 help 1426 If this is set, module text and rod 1172 If this is set, module text and rodata memory will be made read-only, 1427 and non-text memory will be made no 1173 and non-text memory will be made non-executable. This provides 1428 protection against certain security 1174 protection against certain security exploits (e.g. writing to text) 1429 1175 1430 # select if the architecture provides an asm/ 1176 # select if the architecture provides an asm/dma-direct.h header 1431 config ARCH_HAS_PHYS_TO_DMA 1177 config ARCH_HAS_PHYS_TO_DMA 1432 bool 1178 bool 1433 1179 1434 config HAVE_ARCH_COMPILER_H 1180 config HAVE_ARCH_COMPILER_H 1435 bool 1181 bool 1436 help 1182 help 1437 An architecture can select this if 1183 An architecture can select this if it provides an 1438 asm/compiler.h header that should b 1184 asm/compiler.h header that should be included after 1439 linux/compiler-*.h in order to over 1185 linux/compiler-*.h in order to override macro definitions that those 1440 headers generally provide. 1186 headers generally provide. 1441 1187 1442 config HAVE_ARCH_PREL32_RELOCATIONS 1188 config HAVE_ARCH_PREL32_RELOCATIONS 1443 bool 1189 bool 1444 help 1190 help 1445 May be selected by an architecture 1191 May be selected by an architecture if it supports place-relative 1446 32-bit relocations, both in the too 1192 32-bit relocations, both in the toolchain and in the module loader, 1447 in which case relative references c 1193 in which case relative references can be used in special sections 1448 for PCI fixup, initcalls etc which 1194 for PCI fixup, initcalls etc which are only half the size on 64 bit 1449 architectures, and don't require ru 1195 architectures, and don't require runtime relocation on relocatable 1450 kernels. 1196 kernels. 1451 1197 1452 config ARCH_USE_MEMREMAP_PROT 1198 config ARCH_USE_MEMREMAP_PROT 1453 bool 1199 bool 1454 1200 1455 config LOCK_EVENT_COUNTS 1201 config LOCK_EVENT_COUNTS 1456 bool "Locking event counts collection 1202 bool "Locking event counts collection" 1457 depends on DEBUG_FS 1203 depends on DEBUG_FS 1458 help 1204 help 1459 Enable light-weight counting of var 1205 Enable light-weight counting of various locking related events 1460 in the system with minimal performa 1206 in the system with minimal performance impact. This reduces 1461 the chance of application behavior 1207 the chance of application behavior change because of timing 1462 differences. The counts are reporte 1208 differences. The counts are reported via debugfs. 1463 1209 1464 # Select if the architecture has support for 1210 # Select if the architecture has support for applying RELR relocations. 1465 config ARCH_HAS_RELR 1211 config ARCH_HAS_RELR 1466 bool 1212 bool 1467 1213 1468 config RELR 1214 config RELR 1469 bool "Use RELR relocation packing" 1215 bool "Use RELR relocation packing" 1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1216 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1471 default y 1217 default y 1472 help 1218 help 1473 Store the kernel's dynamic relocati 1219 Store the kernel's dynamic relocations in the RELR relocation packing 1474 format. Requires a compatible linke 1220 format. Requires a compatible linker (LLD supports this feature), as 1475 well as compatible NM and OBJCOPY u 1221 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1476 are compatible). 1222 are compatible). 1477 1223 1478 config ARCH_HAS_MEM_ENCRYPT 1224 config ARCH_HAS_MEM_ENCRYPT 1479 bool 1225 bool 1480 1226 1481 config ARCH_HAS_CC_PLATFORM << 1482 bool << 1483 << 1484 config HAVE_SPARSE_SYSCALL_NR 1227 config HAVE_SPARSE_SYSCALL_NR 1485 bool !! 1228 bool 1486 help !! 1229 help 1487 An architecture should select this !! 1230 An architecture should select this if its syscall numbering is sparse 1488 to save space. For example, MIPS ar 1231 to save space. For example, MIPS architecture has a syscall array with 1489 entries at 4000, 5000 and 6000 loca 1232 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1490 related optimizations for a given a 1233 related optimizations for a given architecture. 1491 1234 1492 config ARCH_HAS_VDSO_DATA 1235 config ARCH_HAS_VDSO_DATA 1493 bool 1236 bool 1494 1237 1495 config HAVE_STATIC_CALL 1238 config HAVE_STATIC_CALL 1496 bool 1239 bool 1497 1240 1498 config HAVE_STATIC_CALL_INLINE 1241 config HAVE_STATIC_CALL_INLINE 1499 bool 1242 bool 1500 depends on HAVE_STATIC_CALL 1243 depends on HAVE_STATIC_CALL 1501 select OBJTOOL << 1502 1244 1503 config HAVE_PREEMPT_DYNAMIC 1245 config HAVE_PREEMPT_DYNAMIC 1504 bool 1246 bool 1505 << 1506 config HAVE_PREEMPT_DYNAMIC_CALL << 1507 bool << 1508 depends on HAVE_STATIC_CALL 1247 depends on HAVE_STATIC_CALL 1509 select HAVE_PREEMPT_DYNAMIC !! 1248 depends on GENERIC_ENTRY 1510 help 1249 help 1511 An architecture should select this !! 1250 Select this if the architecture support boot time preempt setting 1512 model being selected at boot time u !! 1251 on top of static calls. It is strongly advised to support inline 1513 !! 1252 static call to avoid any overhead. 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 1253 1541 config ARCH_WANT_LD_ORPHAN_WARN 1254 config ARCH_WANT_LD_ORPHAN_WARN 1542 bool 1255 bool 1543 help 1256 help 1544 An arch should select this symbol o 1257 An arch should select this symbol once all linker sections are explicitly 1545 included, size-asserted, or discard 1258 included, size-asserted, or discarded in the linker scripts. This is 1546 important because we never want exp 1259 important because we never want expected sections to be placed heuristically 1547 by the linker, since the locations 1260 by the linker, since the locations of such sections can change between linker 1548 versions. 1261 versions. 1549 1262 1550 config HAVE_ARCH_PFN_VALID 1263 config HAVE_ARCH_PFN_VALID 1551 bool 1264 bool 1552 1265 1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1266 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1554 bool 1267 bool 1555 1268 1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK << 1557 bool << 1558 << 1559 config ARCH_SPLIT_ARG64 1269 config ARCH_SPLIT_ARG64 1560 bool 1270 bool 1561 help 1271 help 1562 If a 32-bit architecture requires 6 !! 1272 If a 32-bit architecture requires 64-bit arguments to be split into 1563 pairs of 32-bit arguments, select t !! 1273 pairs of 32-bit arguments, select this option. 1564 1274 1565 config ARCH_HAS_ELFCORE_COMPAT 1275 config ARCH_HAS_ELFCORE_COMPAT 1566 bool 1276 bool 1567 1277 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 << 1603 source "kernel/gcov/Kconfig" 1278 source "kernel/gcov/Kconfig" 1604 1279 1605 source "scripts/gcc-plugins/Kconfig" 1280 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 1281 1646 endmenu 1282 endmenu
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