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 ARCH_HAS_SUBPAGE_FAULTS 23 bool 15 bool 24 help 16 help 25 Select if the architecture can check 17 Select if the architecture can check permissions at sub-page 26 granularity (e.g. arm64 MTE). The pr 18 granularity (e.g. arm64 MTE). The probe_user_*() functions 27 must be implemented. 19 must be implemented. 28 20 29 config HOTPLUG_SMT 21 config HOTPLUG_SMT 30 bool 22 bool 31 23 32 config SMT_NUM_THREADS_DYNAMIC 24 config SMT_NUM_THREADS_DYNAMIC 33 bool 25 bool 34 26 35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU 27 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL 36 config HOTPLUG_CORE_SYNC 28 config HOTPLUG_CORE_SYNC 37 bool 29 bool 38 30 39 # Basic CPU dead synchronization selected by a 31 # Basic CPU dead synchronization selected by architecture 40 config HOTPLUG_CORE_SYNC_DEAD 32 config HOTPLUG_CORE_SYNC_DEAD 41 bool 33 bool 42 select HOTPLUG_CORE_SYNC 34 select HOTPLUG_CORE_SYNC 43 35 44 # Full CPU synchronization with alive state se 36 # Full CPU synchronization with alive state selected by architecture 45 config HOTPLUG_CORE_SYNC_FULL 37 config HOTPLUG_CORE_SYNC_FULL 46 bool 38 bool 47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL 39 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU 48 select HOTPLUG_CORE_SYNC 40 select HOTPLUG_CORE_SYNC 49 41 50 config HOTPLUG_SPLIT_STARTUP 42 config HOTPLUG_SPLIT_STARTUP 51 bool 43 bool 52 select HOTPLUG_CORE_SYNC_FULL 44 select HOTPLUG_CORE_SYNC_FULL 53 45 54 config HOTPLUG_PARALLEL 46 config HOTPLUG_PARALLEL 55 bool 47 bool 56 select HOTPLUG_SPLIT_STARTUP 48 select HOTPLUG_SPLIT_STARTUP 57 49 58 config GENERIC_ENTRY 50 config GENERIC_ENTRY 59 bool 51 bool 60 52 61 config KPROBES 53 config KPROBES 62 bool "Kprobes" 54 bool "Kprobes" >> 55 depends on MODULES 63 depends on HAVE_KPROBES 56 depends on HAVE_KPROBES 64 select KALLSYMS 57 select KALLSYMS 65 select EXECMEM !! 58 select TASKS_RCU if PREEMPTION 66 select NEED_TASKS_RCU << 67 help 59 help 68 Kprobes allows you to trap at almost 60 Kprobes allows you to trap at almost any kernel address and 69 execute a callback function. regist 61 execute a callback function. register_kprobe() establishes 70 a probepoint and specifies the callb 62 a probepoint and specifies the callback. Kprobes is useful 71 for kernel debugging, non-intrusive 63 for kernel debugging, non-intrusive instrumentation and testing. 72 If in doubt, say "N". 64 If in doubt, say "N". 73 65 74 config JUMP_LABEL 66 config JUMP_LABEL 75 bool "Optimize very unlikely/likely br 67 bool "Optimize very unlikely/likely branches" 76 depends on HAVE_ARCH_JUMP_LABEL 68 depends on HAVE_ARCH_JUMP_LABEL 77 select OBJTOOL if HAVE_JUMP_LABEL_HACK 69 select OBJTOOL if HAVE_JUMP_LABEL_HACK 78 help 70 help 79 This option enables a transparent br 71 This option enables a transparent branch optimization that 80 makes certain almost-always-true or 72 makes certain almost-always-true or almost-always-false branch 81 conditions even cheaper to execute w 73 conditions even cheaper to execute within the kernel. 82 74 83 Certain performance-sensitive kernel 75 Certain performance-sensitive kernel code, such as trace points, 84 scheduler functionality, networking 76 scheduler functionality, networking code and KVM have such 85 branches and include support for thi 77 branches and include support for this optimization technique. 86 78 87 If it is detected that the compiler 79 If it is detected that the compiler has support for "asm goto", 88 the kernel will compile such branche 80 the kernel will compile such branches with just a nop 89 instruction. When the condition flag 81 instruction. When the condition flag is toggled to true, the 90 nop will be converted to a jump inst 82 nop will be converted to a jump instruction to execute the 91 conditional block of instructions. 83 conditional block of instructions. 92 84 93 This technique lowers overhead and s 85 This technique lowers overhead and stress on the branch prediction 94 of the processor and generally makes 86 of the processor and generally makes the kernel faster. The update 95 of the condition is slower, but thos 87 of the condition is slower, but those are always very rare. 96 88 97 ( On 32-bit x86, the necessary optio 89 ( On 32-bit x86, the necessary options added to the compiler 98 flags may increase the size of the 90 flags may increase the size of the kernel slightly. ) 99 91 100 config STATIC_KEYS_SELFTEST 92 config STATIC_KEYS_SELFTEST 101 bool "Static key selftest" 93 bool "Static key selftest" 102 depends on JUMP_LABEL 94 depends on JUMP_LABEL 103 help 95 help 104 Boot time self-test of the branch pa 96 Boot time self-test of the branch patching code. 105 97 106 config STATIC_CALL_SELFTEST 98 config STATIC_CALL_SELFTEST 107 bool "Static call selftest" 99 bool "Static call selftest" 108 depends on HAVE_STATIC_CALL 100 depends on HAVE_STATIC_CALL 109 help 101 help 110 Boot time self-test of the call patc 102 Boot time self-test of the call patching code. 111 103 112 config OPTPROBES 104 config OPTPROBES 113 def_bool y 105 def_bool y 114 depends on KPROBES && HAVE_OPTPROBES 106 depends on KPROBES && HAVE_OPTPROBES 115 select NEED_TASKS_RCU !! 107 select TASKS_RCU if PREEMPTION 116 108 117 config KPROBES_ON_FTRACE 109 config KPROBES_ON_FTRACE 118 def_bool y 110 def_bool y 119 depends on KPROBES && HAVE_KPROBES_ON_ 111 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 120 depends on DYNAMIC_FTRACE_WITH_REGS 112 depends on DYNAMIC_FTRACE_WITH_REGS 121 help 113 help 122 If function tracer is enabled and th 114 If function tracer is enabled and the arch supports full 123 passing of pt_regs to function traci 115 passing of pt_regs to function tracing, then kprobes can 124 optimize on top of function tracing. 116 optimize on top of function tracing. 125 117 126 config UPROBES 118 config UPROBES 127 def_bool n 119 def_bool n 128 depends on ARCH_SUPPORTS_UPROBES 120 depends on ARCH_SUPPORTS_UPROBES 129 help 121 help 130 Uprobes is the user-space counterpar 122 Uprobes is the user-space counterpart to kprobes: they 131 enable instrumentation applications 123 enable instrumentation applications (such as 'perf probe') 132 to establish unintrusive probes in u 124 to establish unintrusive probes in user-space binaries and 133 libraries, by executing handler func 125 libraries, by executing handler functions when the probes 134 are hit by user-space applications. 126 are hit by user-space applications. 135 127 136 ( These probes come in the form of s 128 ( These probes come in the form of single-byte breakpoints, 137 managed by the kernel and kept tra 129 managed by the kernel and kept transparent to the probed 138 application. ) 130 application. ) 139 131 140 config HAVE_64BIT_ALIGNED_ACCESS 132 config HAVE_64BIT_ALIGNED_ACCESS 141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 133 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 142 help 134 help 143 Some architectures require 64 bit ac 135 Some architectures require 64 bit accesses to be 64 bit 144 aligned, which also requires structs 136 aligned, which also requires structs containing 64 bit values 145 to be 64 bit aligned too. This inclu 137 to be 64 bit aligned too. This includes some 32 bit 146 architectures which can do 64 bit ac 138 architectures which can do 64 bit accesses, as well as 64 bit 147 architectures without unaligned acce 139 architectures without unaligned access. 148 140 149 This symbol should be selected by an 141 This symbol should be selected by an architecture if 64 bit 150 accesses are required to be 64 bit a 142 accesses are required to be 64 bit aligned in this way even 151 though it is not a 64 bit architectu 143 though it is not a 64 bit architecture. 152 144 153 See Documentation/core-api/unaligned 145 See Documentation/core-api/unaligned-memory-access.rst for 154 more information on the topic of una 146 more information on the topic of unaligned memory accesses. 155 147 156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 148 config HAVE_EFFICIENT_UNALIGNED_ACCESS 157 bool 149 bool 158 help 150 help 159 Some architectures are unable to per 151 Some architectures are unable to perform unaligned accesses 160 without the use of get_unaligned/put 152 without the use of get_unaligned/put_unaligned. Others are 161 unable to perform such accesses effi 153 unable to perform such accesses efficiently (e.g. trap on 162 unaligned access and require fixing 154 unaligned access and require fixing it up in the exception 163 handler.) 155 handler.) 164 156 165 This symbol should be selected by an 157 This symbol should be selected by an architecture if it can 166 perform unaligned accesses efficient 158 perform unaligned accesses efficiently to allow different 167 code paths to be selected for these 159 code paths to be selected for these cases. Some network 168 drivers, for example, could opt to n 160 drivers, for example, could opt to not fix up alignment 169 problems with received packets if do 161 problems with received packets if doing so would not help 170 much. 162 much. 171 163 172 See Documentation/core-api/unaligned 164 See Documentation/core-api/unaligned-memory-access.rst for more 173 information on the topic of unaligne 165 information on the topic of unaligned memory accesses. 174 166 175 config ARCH_USE_BUILTIN_BSWAP 167 config ARCH_USE_BUILTIN_BSWAP 176 bool 168 bool 177 help 169 help 178 Modern versions of GCC (since 4.4) h 170 Modern versions of GCC (since 4.4) have builtin functions 179 for handling byte-swapping. Using th 171 for handling byte-swapping. Using these, instead of the old 180 inline assembler that the architectu 172 inline assembler that the architecture code provides in the 181 __arch_bswapXX() macros, allows the 173 __arch_bswapXX() macros, allows the compiler to see what's 182 happening and offers more opportunit 174 happening and offers more opportunity for optimisation. In 183 particular, the compiler will be abl 175 particular, the compiler will be able to combine the byteswap 184 with a nearby load or store and use 176 with a nearby load or store and use load-and-swap or 185 store-and-swap instructions if the a 177 store-and-swap instructions if the architecture has them. It 186 should almost *never* result in code 178 should almost *never* result in code which is worse than the 187 hand-coded assembler in <asm/swab.h> 179 hand-coded assembler in <asm/swab.h>. But just in case it 188 does, the use of the builtins is opt 180 does, the use of the builtins is optional. 189 181 190 Any architecture with load-and-swap 182 Any architecture with load-and-swap or store-and-swap 191 instructions should set this. And it 183 instructions should set this. And it shouldn't hurt to set it 192 on architectures that don't have suc 184 on architectures that don't have such instructions. 193 185 194 config KRETPROBES 186 config KRETPROBES 195 def_bool y 187 def_bool y 196 depends on KPROBES && (HAVE_KRETPROBES 188 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK) 197 189 198 config KRETPROBE_ON_RETHOOK 190 config KRETPROBE_ON_RETHOOK 199 def_bool y 191 def_bool y 200 depends on HAVE_RETHOOK 192 depends on HAVE_RETHOOK 201 depends on KRETPROBES 193 depends on KRETPROBES 202 select RETHOOK 194 select RETHOOK 203 195 204 config USER_RETURN_NOTIFIER 196 config USER_RETURN_NOTIFIER 205 bool 197 bool 206 depends on HAVE_USER_RETURN_NOTIFIER 198 depends on HAVE_USER_RETURN_NOTIFIER 207 help 199 help 208 Provide a kernel-internal notificati 200 Provide a kernel-internal notification when a cpu is about to 209 switch to user mode. 201 switch to user mode. 210 202 211 config HAVE_IOREMAP_PROT 203 config HAVE_IOREMAP_PROT 212 bool 204 bool 213 205 214 config HAVE_KPROBES 206 config HAVE_KPROBES 215 bool 207 bool 216 208 217 config HAVE_KRETPROBES 209 config HAVE_KRETPROBES 218 bool 210 bool 219 211 220 config HAVE_OPTPROBES 212 config HAVE_OPTPROBES 221 bool 213 bool 222 214 223 config HAVE_KPROBES_ON_FTRACE 215 config HAVE_KPROBES_ON_FTRACE 224 bool 216 bool 225 217 226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 218 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 227 bool 219 bool 228 help 220 help 229 Since kretprobes modifies return add 221 Since kretprobes modifies return address on the stack, the 230 stacktrace may see the kretprobe tra 222 stacktrace may see the kretprobe trampoline address instead 231 of correct one. If the architecture 223 of correct one. If the architecture stacktrace code and 232 unwinder can adjust such entries, se 224 unwinder can adjust such entries, select this configuration. 233 225 234 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 232 config HAVE_FUNCTION_DESCRIPTORS 241 bool 233 bool 242 234 243 config TRACE_IRQFLAGS_SUPPORT 235 config TRACE_IRQFLAGS_SUPPORT 244 bool 236 bool 245 237 246 config TRACE_IRQFLAGS_NMI_SUPPORT 238 config TRACE_IRQFLAGS_NMI_SUPPORT 247 bool 239 bool 248 240 249 # 241 # 250 # An arch should select this if it provides al 242 # An arch should select this if it provides all these things: 251 # 243 # 252 # task_pt_regs() in asm/process 244 # task_pt_regs() in asm/processor.h or asm/ptrace.h 253 # arch_has_single_step() if there is ha 245 # arch_has_single_step() if there is hardware single-step support 254 # arch_has_block_step() if there is ha 246 # arch_has_block_step() if there is hardware block-step support 255 # asm/syscall.h supplying asm- 247 # asm/syscall.h supplying asm-generic/syscall.h interface 256 # linux/regset.h user_regset in 248 # linux/regset.h user_regset interfaces 257 # CORE_DUMP_USE_REGSET #define'd in l 249 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h 258 # TIF_SYSCALL_TRACE calls ptrace_r 250 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit} 259 # TIF_NOTIFY_RESUME calls resume_u 251 # TIF_NOTIFY_RESUME calls resume_user_mode_work() 260 # 252 # 261 config HAVE_ARCH_TRACEHOOK 253 config HAVE_ARCH_TRACEHOOK 262 bool 254 bool 263 255 264 config HAVE_DMA_CONTIGUOUS 256 config HAVE_DMA_CONTIGUOUS 265 bool 257 bool 266 258 267 config GENERIC_SMP_IDLE_THREAD 259 config GENERIC_SMP_IDLE_THREAD 268 bool 260 bool 269 261 270 config GENERIC_IDLE_POLL_SETUP 262 config GENERIC_IDLE_POLL_SETUP 271 bool 263 bool 272 264 273 config ARCH_HAS_FORTIFY_SOURCE 265 config ARCH_HAS_FORTIFY_SOURCE 274 bool 266 bool 275 help 267 help 276 An architecture should select this w 268 An architecture should select this when it can successfully 277 build and run with CONFIG_FORTIFY_SO 269 build and run with CONFIG_FORTIFY_SOURCE. 278 270 279 # 271 # 280 # Select if the arch provides a historic keepi 272 # Select if the arch provides a historic keepinit alias for the retain_initrd 281 # command line option 273 # command line option 282 # 274 # 283 config ARCH_HAS_KEEPINITRD 275 config ARCH_HAS_KEEPINITRD 284 bool 276 bool 285 277 286 # Select if arch has all set_memory_ro/rw/x/nx 278 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 287 config ARCH_HAS_SET_MEMORY 279 config ARCH_HAS_SET_MEMORY 288 bool 280 bool 289 281 290 # Select if arch has all set_direct_map_invali 282 # Select if arch has all set_direct_map_invalid/default() functions 291 config ARCH_HAS_SET_DIRECT_MAP 283 config ARCH_HAS_SET_DIRECT_MAP 292 bool 284 bool 293 285 294 # 286 # 295 # Select if the architecture provides the arch 287 # Select if the architecture provides the arch_dma_set_uncached symbol to 296 # either provide an uncached segment alias for 288 # either provide an uncached segment alias for a DMA allocation, or 297 # to remap the page tables in place. 289 # to remap the page tables in place. 298 # 290 # 299 config ARCH_HAS_DMA_SET_UNCACHED 291 config ARCH_HAS_DMA_SET_UNCACHED 300 bool 292 bool 301 293 302 # 294 # 303 # Select if the architectures provides the arc 295 # Select if the architectures provides the arch_dma_clear_uncached symbol 304 # to undo an in-place page table remap for unc 296 # to undo an in-place page table remap for uncached access. 305 # 297 # 306 config ARCH_HAS_DMA_CLEAR_UNCACHED 298 config ARCH_HAS_DMA_CLEAR_UNCACHED 307 bool 299 bool 308 300 309 config ARCH_HAS_CPU_FINALIZE_INIT 301 config ARCH_HAS_CPU_FINALIZE_INIT 310 bool 302 bool 311 303 312 # The architecture has a per-task state that i !! 304 # Select if arch init_task must go in the __init_task_data section 313 config ARCH_HAS_CPU_PASID !! 305 config ARCH_TASK_STRUCT_ON_STACK >> 306 bool >> 307 >> 308 # Select if arch has its private alloc_task_struct() function >> 309 config ARCH_TASK_STRUCT_ALLOCATOR 314 bool 310 bool 315 select IOMMU_MM_DATA << 316 311 317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 312 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 318 bool 313 bool >> 314 depends on !ARCH_TASK_STRUCT_ALLOCATOR 319 help 315 help 320 An architecture should select this t 316 An architecture should select this to provide hardened usercopy 321 knowledge about what region of the t 317 knowledge about what region of the thread_struct should be 322 whitelisted for copying to userspace 318 whitelisted for copying to userspace. Normally this is only the 323 FPU registers. Specifically, arch_th 319 FPU registers. Specifically, arch_thread_struct_whitelist() 324 should be implemented. Without this, 320 should be implemented. Without this, the entire thread_struct 325 field in task_struct will be left wh 321 field in task_struct will be left whitelisted. 326 322 >> 323 # Select if arch has its private alloc_thread_stack() function >> 324 config ARCH_THREAD_STACK_ALLOCATOR >> 325 bool >> 326 327 # Select if arch wants to size task_struct dyn 327 # Select if arch wants to size task_struct dynamically via arch_task_struct_size: 328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 329 bool 329 bool 330 330 331 config ARCH_WANTS_NO_INSTR 331 config ARCH_WANTS_NO_INSTR 332 bool 332 bool 333 help 333 help 334 An architecture should select this i 334 An architecture should select this if the noinstr macro is being used on 335 functions to denote that the toolcha 335 functions to denote that the toolchain should avoid instrumenting such 336 functions and is required for correc 336 functions and is required for correctness. 337 337 338 config ARCH_32BIT_OFF_T 338 config ARCH_32BIT_OFF_T 339 bool 339 bool 340 depends on !64BIT 340 depends on !64BIT 341 help 341 help 342 All new 32-bit architectures should 342 All new 32-bit architectures should have 64-bit off_t type on 343 userspace side which corresponds to 343 userspace side which corresponds to the loff_t kernel type. This 344 is the requirement for modern ABIs. 344 is the requirement for modern ABIs. Some existing architectures 345 still support 32-bit off_t. This opt 345 still support 32-bit off_t. This option is enabled for all such 346 architectures explicitly. 346 architectures explicitly. 347 347 348 # Selected by 64 bit architectures which have 348 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 349 config ARCH_32BIT_USTAT_F_TINODE 349 config ARCH_32BIT_USTAT_F_TINODE 350 bool 350 bool 351 351 352 config HAVE_ASM_MODVERSIONS 352 config HAVE_ASM_MODVERSIONS 353 bool 353 bool 354 help 354 help 355 This symbol should be selected by an 355 This symbol should be selected by an architecture if it provides 356 <asm/asm-prototypes.h> to support th 356 <asm/asm-prototypes.h> to support the module versioning for symbols 357 exported from assembly code. 357 exported from assembly code. 358 358 359 config HAVE_REGS_AND_STACK_ACCESS_API 359 config HAVE_REGS_AND_STACK_ACCESS_API 360 bool 360 bool 361 help 361 help 362 This symbol should be selected by an 362 This symbol should be selected by an architecture if it supports 363 the API needed to access registers a 363 the API needed to access registers and stack entries from pt_regs, 364 declared in asm/ptrace.h 364 declared in asm/ptrace.h 365 For example the kprobes-based event 365 For example the kprobes-based event tracer needs this API. 366 366 367 config HAVE_RSEQ 367 config HAVE_RSEQ 368 bool 368 bool 369 depends on HAVE_REGS_AND_STACK_ACCESS_ 369 depends on HAVE_REGS_AND_STACK_ACCESS_API 370 help 370 help 371 This symbol should be selected by an 371 This symbol should be selected by an architecture if it 372 supports an implementation of restar 372 supports an implementation of restartable sequences. 373 373 374 config HAVE_RUST 374 config HAVE_RUST 375 bool 375 bool 376 help 376 help 377 This symbol should be selected by an 377 This symbol should be selected by an architecture if it 378 supports Rust. 378 supports Rust. 379 379 380 config HAVE_FUNCTION_ARG_ACCESS_API 380 config HAVE_FUNCTION_ARG_ACCESS_API 381 bool 381 bool 382 help 382 help 383 This symbol should be selected by an 383 This symbol should be selected by an architecture if it supports 384 the API needed to access function ar 384 the API needed to access function arguments from pt_regs, 385 declared in asm/ptrace.h 385 declared in asm/ptrace.h 386 386 387 config HAVE_HW_BREAKPOINT 387 config HAVE_HW_BREAKPOINT 388 bool 388 bool 389 depends on PERF_EVENTS 389 depends on PERF_EVENTS 390 390 391 config HAVE_MIXED_BREAKPOINTS_REGS 391 config HAVE_MIXED_BREAKPOINTS_REGS 392 bool 392 bool 393 depends on HAVE_HW_BREAKPOINT 393 depends on HAVE_HW_BREAKPOINT 394 help 394 help 395 Depending on the arch implementation 395 Depending on the arch implementation of hardware breakpoints, 396 some of them have separate registers 396 some of them have separate registers for data and instruction 397 breakpoints addresses, others have m 397 breakpoints addresses, others have mixed registers to store 398 them but define the access type in a 398 them but define the access type in a control register. 399 Select this option if your arch impl 399 Select this option if your arch implements breakpoints under the 400 latter fashion. 400 latter fashion. 401 401 402 config HAVE_USER_RETURN_NOTIFIER 402 config HAVE_USER_RETURN_NOTIFIER 403 bool 403 bool 404 404 405 config HAVE_PERF_EVENTS_NMI 405 config HAVE_PERF_EVENTS_NMI 406 bool 406 bool 407 help 407 help 408 System hardware can generate an NMI 408 System hardware can generate an NMI using the perf event 409 subsystem. Also has support for cal 409 subsystem. Also has support for calculating CPU cycle events 410 to determine how many clock cycles i 410 to determine how many clock cycles in a given period. 411 411 412 config HAVE_HARDLOCKUP_DETECTOR_PERF 412 config HAVE_HARDLOCKUP_DETECTOR_PERF 413 bool 413 bool 414 depends on HAVE_PERF_EVENTS_NMI 414 depends on HAVE_PERF_EVENTS_NMI 415 help 415 help 416 The arch chooses to use the generic 416 The arch chooses to use the generic perf-NMI-based hardlockup 417 detector. Must define HAVE_PERF_EVEN 417 detector. Must define HAVE_PERF_EVENTS_NMI. 418 418 419 config HAVE_HARDLOCKUP_DETECTOR_ARCH 419 config HAVE_HARDLOCKUP_DETECTOR_ARCH 420 bool 420 bool 421 help 421 help 422 The arch provides its own hardlockup 422 The arch provides its own hardlockup detector implementation instead 423 of the generic ones. 423 of the generic ones. 424 424 425 It uses the same command line parame 425 It uses the same command line parameters, and sysctl interface, 426 as the generic hardlockup detectors. 426 as the generic hardlockup detectors. 427 427 428 config HAVE_PERF_REGS 428 config HAVE_PERF_REGS 429 bool 429 bool 430 help 430 help 431 Support selective register dumps for 431 Support selective register dumps for perf events. This includes 432 bit-mapping of each registers and a 432 bit-mapping of each registers and a unique architecture id. 433 433 434 config HAVE_PERF_USER_STACK_DUMP 434 config HAVE_PERF_USER_STACK_DUMP 435 bool 435 bool 436 help 436 help 437 Support user stack dumps for perf ev 437 Support user stack dumps for perf event samples. This needs 438 access to the user stack pointer whi 438 access to the user stack pointer which is not unified across 439 architectures. 439 architectures. 440 440 441 config HAVE_ARCH_JUMP_LABEL 441 config HAVE_ARCH_JUMP_LABEL 442 bool 442 bool 443 443 444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 445 bool 445 bool 446 446 447 config MMU_GATHER_TABLE_FREE 447 config MMU_GATHER_TABLE_FREE 448 bool 448 bool 449 449 450 config MMU_GATHER_RCU_TABLE_FREE 450 config MMU_GATHER_RCU_TABLE_FREE 451 bool 451 bool 452 select MMU_GATHER_TABLE_FREE 452 select MMU_GATHER_TABLE_FREE 453 453 454 config MMU_GATHER_PAGE_SIZE 454 config MMU_GATHER_PAGE_SIZE 455 bool 455 bool 456 456 457 config MMU_GATHER_NO_RANGE 457 config MMU_GATHER_NO_RANGE 458 bool 458 bool 459 select MMU_GATHER_MERGE_VMAS 459 select MMU_GATHER_MERGE_VMAS 460 460 461 config MMU_GATHER_NO_FLUSH_CACHE 461 config MMU_GATHER_NO_FLUSH_CACHE 462 bool 462 bool 463 463 464 config MMU_GATHER_MERGE_VMAS 464 config MMU_GATHER_MERGE_VMAS 465 bool 465 bool 466 466 467 config MMU_GATHER_NO_GATHER 467 config MMU_GATHER_NO_GATHER 468 bool 468 bool 469 depends on MMU_GATHER_TABLE_FREE 469 depends on MMU_GATHER_TABLE_FREE 470 470 471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 472 bool 472 bool 473 help 473 help 474 Temporary select until all architect 474 Temporary select until all architectures can be converted to have 475 irqs disabled over activate_mm. Arch 475 irqs disabled over activate_mm. Architectures that do IPI based TLB 476 shootdowns should enable this. 476 shootdowns should enable this. 477 477 478 # Use normal mm refcounting for MMU_LAZY_TLB k 478 # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. 479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal 479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching 480 # to/from kernel threads when the same mm is r 480 # to/from kernel threads when the same mm is running on a lot of CPUs (a large 481 # multi-threaded application), by reducing con 481 # multi-threaded application), by reducing contention on the mm refcount. 482 # 482 # 483 # This can be disabled if the architecture ens 483 # This can be disabled if the architecture ensures no CPUs are using an mm as a 484 # "lazy tlb" beyond its final refcount (i.e., 484 # "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm 485 # or its kernel page tables). This could be ar 485 # or its kernel page tables). This could be arranged by arch_exit_mmap(), or 486 # final exit(2) TLB flush, for example. 486 # final exit(2) TLB flush, for example. 487 # 487 # 488 # To implement this, an arch *must*: 488 # To implement this, an arch *must*: 489 # Ensure the _lazy_tlb variants of mmgrab/mmdr 489 # Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating 490 # the lazy tlb reference of a kthread's ->acti 490 # the lazy tlb reference of a kthread's ->active_mm (non-arch code has been 491 # converted already). 491 # converted already). 492 config MMU_LAZY_TLB_REFCOUNT 492 config MMU_LAZY_TLB_REFCOUNT 493 def_bool y 493 def_bool y 494 depends on !MMU_LAZY_TLB_SHOOTDOWN 494 depends on !MMU_LAZY_TLB_SHOOTDOWN 495 495 496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. 496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an 497 # mm as a lazy tlb beyond its last reference c 497 # mm as a lazy tlb beyond its last reference count, by shooting down these 498 # users before the mm is deallocated. __mmdrop 498 # users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may 499 # be using the mm as a lazy tlb, so that they 499 # be using the mm as a lazy tlb, so that they may switch themselves to using 500 # init_mm for their active mm. mm_cpumask(mm) 500 # init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs 501 # may be using mm as a lazy tlb mm. 501 # may be using mm as a lazy tlb mm. 502 # 502 # 503 # To implement this, an arch *must*: 503 # To implement this, an arch *must*: 504 # - At the time of the final mmdrop of the mm, 504 # - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains 505 # at least all possible CPUs in which the mm 505 # at least all possible CPUs in which the mm is lazy. 506 # - It must meet the requirements for MMU_LAZY 506 # - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). 507 config MMU_LAZY_TLB_SHOOTDOWN 507 config MMU_LAZY_TLB_SHOOTDOWN 508 bool 508 bool 509 509 510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 511 bool 511 bool 512 512 513 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 513 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 523 bool 514 bool 524 515 525 config HAVE_ALIGNED_STRUCT_PAGE 516 config HAVE_ALIGNED_STRUCT_PAGE 526 bool 517 bool 527 help 518 help 528 This makes sure that struct pages ar 519 This makes sure that struct pages are double word aligned and that 529 e.g. the SLUB allocator can perform 520 e.g. the SLUB allocator can perform double word atomic operations 530 on a struct page for better performa 521 on a struct page for better performance. However selecting this 531 might increase the size of a struct 522 might increase the size of a struct page by a word. 532 523 533 config HAVE_CMPXCHG_LOCAL 524 config HAVE_CMPXCHG_LOCAL 534 bool 525 bool 535 526 536 config HAVE_CMPXCHG_DOUBLE 527 config HAVE_CMPXCHG_DOUBLE 537 bool 528 bool 538 529 539 config ARCH_WEAK_RELEASE_ACQUIRE 530 config ARCH_WEAK_RELEASE_ACQUIRE 540 bool 531 bool 541 532 542 config ARCH_WANT_IPC_PARSE_VERSION 533 config ARCH_WANT_IPC_PARSE_VERSION 543 bool 534 bool 544 535 545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 536 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 546 bool 537 bool 547 538 548 config ARCH_WANT_OLD_COMPAT_IPC 539 config ARCH_WANT_OLD_COMPAT_IPC 549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 540 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 550 bool 541 bool 551 542 552 config HAVE_ARCH_SECCOMP 543 config HAVE_ARCH_SECCOMP 553 bool 544 bool 554 help 545 help 555 An arch should select this symbol to 546 An arch should select this symbol to support seccomp mode 1 (the fixed 556 syscall policy), and must provide an 547 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 557 and compat syscalls if the asm-gener 548 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 558 - __NR_seccomp_read_32 549 - __NR_seccomp_read_32 559 - __NR_seccomp_write_32 550 - __NR_seccomp_write_32 560 - __NR_seccomp_exit_32 551 - __NR_seccomp_exit_32 561 - __NR_seccomp_sigreturn_32 552 - __NR_seccomp_sigreturn_32 562 553 563 config HAVE_ARCH_SECCOMP_FILTER 554 config HAVE_ARCH_SECCOMP_FILTER 564 bool 555 bool 565 select HAVE_ARCH_SECCOMP 556 select HAVE_ARCH_SECCOMP 566 help 557 help 567 An arch should select this symbol if 558 An arch should select this symbol if it provides all of these things: 568 - all the requirements for HAVE_ARCH 559 - all the requirements for HAVE_ARCH_SECCOMP 569 - syscall_get_arch() 560 - syscall_get_arch() 570 - syscall_get_arguments() 561 - syscall_get_arguments() 571 - syscall_rollback() 562 - syscall_rollback() 572 - syscall_set_return_value() 563 - syscall_set_return_value() 573 - SIGSYS siginfo_t support 564 - SIGSYS siginfo_t support 574 - secure_computing is called from a 565 - secure_computing is called from a ptrace_event()-safe context 575 - secure_computing return value is c 566 - secure_computing return value is checked and a return value of -1 576 results in the system call being s 567 results in the system call being skipped immediately. 577 - seccomp syscall wired up 568 - seccomp syscall wired up 578 - if !HAVE_SPARSE_SYSCALL_NR, have S 569 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 570 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 580 COMPAT is supported, have the SECC 571 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 581 572 582 config SECCOMP 573 config SECCOMP 583 prompt "Enable seccomp to safely execu 574 prompt "Enable seccomp to safely execute untrusted bytecode" 584 def_bool y 575 def_bool y 585 depends on HAVE_ARCH_SECCOMP 576 depends on HAVE_ARCH_SECCOMP 586 help 577 help 587 This kernel feature is useful for nu 578 This kernel feature is useful for number crunching applications 588 that may need to handle untrusted by 579 that may need to handle untrusted bytecode during their 589 execution. By using pipes or other t 580 execution. By using pipes or other transports made available 590 to the process as file descriptors s 581 to the process as file descriptors supporting the read/write 591 syscalls, it's possible to isolate t 582 syscalls, it's possible to isolate those applications in their 592 own address space using seccomp. Onc 583 own address space using seccomp. Once seccomp is enabled via 593 prctl(PR_SET_SECCOMP) or the seccomp 584 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 594 disabled and the task is only allowe 585 disabled and the task is only allowed to execute a few safe 595 syscalls defined by each seccomp mod 586 syscalls defined by each seccomp mode. 596 587 597 If unsure, say Y. 588 If unsure, say Y. 598 589 599 config SECCOMP_FILTER 590 config SECCOMP_FILTER 600 def_bool y 591 def_bool y 601 depends on HAVE_ARCH_SECCOMP_FILTER && 592 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 602 help 593 help 603 Enable tasks to build secure computi 594 Enable tasks to build secure computing environments defined 604 in terms of Berkeley Packet Filter p 595 in terms of Berkeley Packet Filter programs which implement 605 task-defined system call filtering p 596 task-defined system call filtering polices. 606 597 607 See Documentation/userspace-api/secc 598 See Documentation/userspace-api/seccomp_filter.rst for details. 608 599 609 config SECCOMP_CACHE_DEBUG 600 config SECCOMP_CACHE_DEBUG 610 bool "Show seccomp filter cache status 601 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 611 depends on SECCOMP_FILTER && !HAVE_SPA 602 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 612 depends on PROC_FS 603 depends on PROC_FS 613 help 604 help 614 This enables the /proc/pid/seccomp_c 605 This enables the /proc/pid/seccomp_cache interface to monitor 615 seccomp cache data. The file format 606 seccomp cache data. The file format is subject to change. Reading 616 the file requires CAP_SYS_ADMIN. 607 the file requires CAP_SYS_ADMIN. 617 608 618 This option is for debugging only. E 609 This option is for debugging only. Enabling presents the risk that 619 an adversary may be able to infer th 610 an adversary may be able to infer the seccomp filter logic. 620 611 621 If unsure, say N. 612 If unsure, say N. 622 613 623 config HAVE_ARCH_STACKLEAK 614 config HAVE_ARCH_STACKLEAK 624 bool 615 bool 625 help 616 help 626 An architecture should select this i 617 An architecture should select this if it has the code which 627 fills the used part of the kernel st 618 fills the used part of the kernel stack with the STACKLEAK_POISON 628 value before returning from system c 619 value before returning from system calls. 629 620 630 config HAVE_STACKPROTECTOR 621 config HAVE_STACKPROTECTOR 631 bool 622 bool 632 help 623 help 633 An arch should select this symbol if 624 An arch should select this symbol if: 634 - it has implemented a stack canary 625 - it has implemented a stack canary (e.g. __stack_chk_guard) 635 626 636 config STACKPROTECTOR 627 config STACKPROTECTOR 637 bool "Stack Protector buffer overflow 628 bool "Stack Protector buffer overflow detection" 638 depends on HAVE_STACKPROTECTOR 629 depends on HAVE_STACKPROTECTOR 639 depends on $(cc-option,-fstack-protect 630 depends on $(cc-option,-fstack-protector) 640 default y 631 default y 641 help 632 help 642 This option turns on the "stack-prot 633 This option turns on the "stack-protector" GCC feature. This 643 feature puts, at the beginning of fu 634 feature puts, at the beginning of functions, a canary value on 644 the stack just before the return add 635 the stack just before the return address, and validates 645 the value just before actually retur 636 the value just before actually returning. Stack based buffer 646 overflows (that need to overwrite th 637 overflows (that need to overwrite this return address) now also 647 overwrite the canary, which gets det 638 overwrite the canary, which gets detected and the attack is then 648 neutralized via a kernel panic. 639 neutralized via a kernel panic. 649 640 650 Functions will have the stack-protec 641 Functions will have the stack-protector canary logic added if they 651 have an 8-byte or larger character a 642 have an 8-byte or larger character array on the stack. 652 643 653 This feature requires gcc version 4. 644 This feature requires gcc version 4.2 or above, or a distribution 654 gcc with the feature backported ("-f 645 gcc with the feature backported ("-fstack-protector"). 655 646 656 On an x86 "defconfig" build, this fe 647 On an x86 "defconfig" build, this feature adds canary checks to 657 about 3% of all kernel functions, wh 648 about 3% of all kernel functions, which increases kernel code size 658 by about 0.3%. 649 by about 0.3%. 659 650 660 config STACKPROTECTOR_STRONG 651 config STACKPROTECTOR_STRONG 661 bool "Strong Stack Protector" 652 bool "Strong Stack Protector" 662 depends on STACKPROTECTOR 653 depends on STACKPROTECTOR 663 depends on $(cc-option,-fstack-protect 654 depends on $(cc-option,-fstack-protector-strong) 664 default y 655 default y 665 help 656 help 666 Functions will have the stack-protec 657 Functions will have the stack-protector canary logic added in any 667 of the following conditions: 658 of the following conditions: 668 659 669 - local variable's address used as p 660 - local variable's address used as part of the right hand side of an 670 assignment or function argument 661 assignment or function argument 671 - local variable is an array (or uni 662 - local variable is an array (or union containing an array), 672 regardless of array type or length 663 regardless of array type or length 673 - uses register local variables 664 - uses register local variables 674 665 675 This feature requires gcc version 4. 666 This feature requires gcc version 4.9 or above, or a distribution 676 gcc with the feature backported ("-f 667 gcc with the feature backported ("-fstack-protector-strong"). 677 668 678 On an x86 "defconfig" build, this fe 669 On an x86 "defconfig" build, this feature adds canary checks to 679 about 20% of all kernel functions, w 670 about 20% of all kernel functions, which increases the kernel code 680 size by about 2%. 671 size by about 2%. 681 672 682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 673 config ARCH_SUPPORTS_SHADOW_CALL_STACK 683 bool 674 bool 684 help 675 help 685 An architecture should select this i 676 An architecture should select this if it supports the compiler's 686 Shadow Call Stack and implements run 677 Shadow Call Stack and implements runtime support for shadow stack 687 switching. 678 switching. 688 679 689 config SHADOW_CALL_STACK 680 config SHADOW_CALL_STACK 690 bool "Shadow Call Stack" 681 bool "Shadow Call Stack" 691 depends on ARCH_SUPPORTS_SHADOW_CALL_S 682 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK 692 depends on DYNAMIC_FTRACE_WITH_ARGS || 683 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 693 depends on MMU 684 depends on MMU 694 help 685 help 695 This option enables the compiler's S 686 This option enables the compiler's Shadow Call Stack, which 696 uses a shadow stack to protect funct 687 uses a shadow stack to protect function return addresses from 697 being overwritten by an attacker. Mo 688 being overwritten by an attacker. More information can be found 698 in the compiler's documentation: 689 in the compiler's documentation: 699 690 700 - Clang: https://clang.llvm.org/docs 691 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html 701 - GCC: https://gcc.gnu.org/onlinedoc 692 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options 702 693 703 Note that security guarantees in the 694 Note that security guarantees in the kernel differ from the 704 ones documented for user space. The 695 ones documented for user space. The kernel must store addresses 705 of shadow stacks in memory, which me 696 of shadow stacks in memory, which means an attacker capable of 706 reading and writing arbitrary memory 697 reading and writing arbitrary memory may be able to locate them 707 and hijack control flow by modifying 698 and hijack control flow by modifying the stacks. 708 699 709 config DYNAMIC_SCS 700 config DYNAMIC_SCS 710 bool 701 bool 711 help 702 help 712 Set by the arch code if it relies on 703 Set by the arch code if it relies on code patching to insert the 713 shadow call stack push and pop instr 704 shadow call stack push and pop instructions rather than on the 714 compiler. 705 compiler. 715 706 716 config LTO 707 config LTO 717 bool 708 bool 718 help 709 help 719 Selected if the kernel will be built 710 Selected if the kernel will be built using the compiler's LTO feature. 720 711 721 config LTO_CLANG 712 config LTO_CLANG 722 bool 713 bool 723 select LTO 714 select LTO 724 help 715 help 725 Selected if the kernel will be built 716 Selected if the kernel will be built using Clang's LTO feature. 726 717 727 config ARCH_SUPPORTS_LTO_CLANG 718 config ARCH_SUPPORTS_LTO_CLANG 728 bool 719 bool 729 help 720 help 730 An architecture should select this o 721 An architecture should select this option if it supports: 731 - compiling with Clang, 722 - compiling with Clang, 732 - compiling inline assembly with Cla 723 - compiling inline assembly with Clang's integrated assembler, 733 - and linking with LLD. 724 - and linking with LLD. 734 725 735 config ARCH_SUPPORTS_LTO_CLANG_THIN 726 config ARCH_SUPPORTS_LTO_CLANG_THIN 736 bool 727 bool 737 help 728 help 738 An architecture should select this o 729 An architecture should select this option if it can support Clang's 739 ThinLTO mode. 730 ThinLTO mode. 740 731 741 config HAS_LTO_CLANG 732 config HAS_LTO_CLANG 742 def_bool y 733 def_bool y 743 depends on CC_IS_CLANG && LD_IS_LLD && 734 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM 744 depends on $(success,$(NM) --help | he 735 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 745 depends on $(success,$(AR) --help | he 736 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 746 depends on ARCH_SUPPORTS_LTO_CLANG 737 depends on ARCH_SUPPORTS_LTO_CLANG 747 depends on !FTRACE_MCOUNT_USE_RECORDMC 738 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 748 # https://github.com/ClangBuiltLinux/l 739 # https://github.com/ClangBuiltLinux/linux/issues/1721 749 depends on (!KASAN || KASAN_HW_TAGS || 740 depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO 750 depends on (!KCOV || CLANG_VERSION >= 741 depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO 751 depends on !GCOV_KERNEL 742 depends on !GCOV_KERNEL 752 help 743 help 753 The compiler and Kconfig options sup 744 The compiler and Kconfig options support building with Clang's 754 LTO. 745 LTO. 755 746 756 choice 747 choice 757 prompt "Link Time Optimization (LTO)" 748 prompt "Link Time Optimization (LTO)" 758 default LTO_NONE 749 default LTO_NONE 759 help 750 help 760 This option enables Link Time Optimi 751 This option enables Link Time Optimization (LTO), which allows the 761 compiler to optimize binaries global 752 compiler to optimize binaries globally. 762 753 763 If unsure, select LTO_NONE. Note tha 754 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 764 so it's disabled by default. 755 so it's disabled by default. 765 756 766 config LTO_NONE 757 config LTO_NONE 767 bool "None" 758 bool "None" 768 help 759 help 769 Build the kernel normally, without L 760 Build the kernel normally, without Link Time Optimization (LTO). 770 761 771 config LTO_CLANG_FULL 762 config LTO_CLANG_FULL 772 bool "Clang Full LTO (EXPERIMENTAL)" 763 bool "Clang Full LTO (EXPERIMENTAL)" 773 depends on HAS_LTO_CLANG 764 depends on HAS_LTO_CLANG 774 depends on !COMPILE_TEST 765 depends on !COMPILE_TEST 775 select LTO_CLANG 766 select LTO_CLANG 776 help 767 help 777 This option enables Clang's full Lin 768 This option enables Clang's full Link Time Optimization (LTO), which 778 allows the compiler to optimize the 769 allows the compiler to optimize the kernel globally. If you enable 779 this option, the compiler generates 770 this option, the compiler generates LLVM bitcode instead of ELF 780 object files, and the actual compila 771 object files, and the actual compilation from bitcode happens at 781 the LTO link step, which may take se 772 the LTO link step, which may take several minutes depending on the 782 kernel configuration. More informati 773 kernel configuration. More information can be found from LLVM's 783 documentation: 774 documentation: 784 775 785 https://llvm.org/docs/LinkTimeOpti 776 https://llvm.org/docs/LinkTimeOptimization.html 786 777 787 During link time, this option can us 778 During link time, this option can use a large amount of RAM, and 788 may take much longer than the ThinLT 779 may take much longer than the ThinLTO option. 789 780 790 config LTO_CLANG_THIN 781 config LTO_CLANG_THIN 791 bool "Clang ThinLTO (EXPERIMENTAL)" 782 bool "Clang ThinLTO (EXPERIMENTAL)" 792 depends on HAS_LTO_CLANG && ARCH_SUPPO 783 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 793 select LTO_CLANG 784 select LTO_CLANG 794 help 785 help 795 This option enables Clang's ThinLTO, 786 This option enables Clang's ThinLTO, which allows for parallel 796 optimization and faster incremental 787 optimization and faster incremental compiles compared to the 797 CONFIG_LTO_CLANG_FULL option. More i 788 CONFIG_LTO_CLANG_FULL option. More information can be found 798 from Clang's documentation: 789 from Clang's documentation: 799 790 800 https://clang.llvm.org/docs/ThinLT 791 https://clang.llvm.org/docs/ThinLTO.html 801 792 802 If unsure, say Y. 793 If unsure, say Y. 803 endchoice 794 endchoice 804 795 805 config ARCH_SUPPORTS_CFI_CLANG 796 config ARCH_SUPPORTS_CFI_CLANG 806 bool 797 bool 807 help 798 help 808 An architecture should select this o 799 An architecture should select this option if it can support Clang's 809 Control-Flow Integrity (CFI) checkin 800 Control-Flow Integrity (CFI) checking. 810 801 811 config ARCH_USES_CFI_TRAPS 802 config ARCH_USES_CFI_TRAPS 812 bool 803 bool 813 804 814 config CFI_CLANG 805 config CFI_CLANG 815 bool "Use Clang's Control Flow Integri 806 bool "Use Clang's Control Flow Integrity (CFI)" 816 depends on ARCH_SUPPORTS_CFI_CLANG 807 depends on ARCH_SUPPORTS_CFI_CLANG 817 depends on $(cc-option,-fsanitize=kcfi 808 depends on $(cc-option,-fsanitize=kcfi) 818 help 809 help 819 This option enables Clang's forward- !! 810 This option enables Clang’s forward-edge Control Flow Integrity 820 (CFI) checking, where the compiler i 811 (CFI) checking, where the compiler injects a runtime check to each 821 indirect function call to ensure the 812 indirect function call to ensure the target is a valid function with 822 the correct static type. This restri 813 the correct static type. This restricts possible call targets and 823 makes it more difficult for an attac 814 makes it more difficult for an attacker to exploit bugs that allow 824 the modification of stored function 815 the modification of stored function pointers. More information can be 825 found from Clang's documentation: 816 found from Clang's documentation: 826 817 827 https://clang.llvm.org/docs/Contro 818 https://clang.llvm.org/docs/ControlFlowIntegrity.html 828 819 829 config CFI_PERMISSIVE 820 config CFI_PERMISSIVE 830 bool "Use CFI in permissive mode" 821 bool "Use CFI in permissive mode" 831 depends on CFI_CLANG 822 depends on CFI_CLANG 832 help 823 help 833 When selected, Control Flow Integrit 824 When selected, Control Flow Integrity (CFI) violations result in a 834 warning instead of a kernel panic. T 825 warning instead of a kernel panic. This option should only be used 835 for finding indirect call type misma 826 for finding indirect call type mismatches during development. 836 827 837 If unsure, say N. 828 If unsure, say N. 838 829 839 config HAVE_ARCH_WITHIN_STACK_FRAMES 830 config HAVE_ARCH_WITHIN_STACK_FRAMES 840 bool 831 bool 841 help 832 help 842 An architecture should select this i 833 An architecture should select this if it can walk the kernel stack 843 frames to determine if an object is 834 frames to determine if an object is part of either the arguments 844 or local variables (i.e. that it exc 835 or local variables (i.e. that it excludes saved return addresses, 845 and similar) by implementing an inli 836 and similar) by implementing an inline arch_within_stack_frames(), 846 which is used by CONFIG_HARDENED_USE 837 which is used by CONFIG_HARDENED_USERCOPY. 847 838 848 config HAVE_CONTEXT_TRACKING_USER 839 config HAVE_CONTEXT_TRACKING_USER 849 bool 840 bool 850 help 841 help 851 Provide kernel/user boundaries probe 842 Provide kernel/user boundaries probes necessary for subsystems 852 that need it, such as userspace RCU 843 that need it, such as userspace RCU extended quiescent state. 853 Syscalls need to be wrapped inside u 844 Syscalls need to be wrapped inside user_exit()-user_enter(), either 854 optimized behind static key or throu 845 optimized behind static key or through the slow path using TIF_NOHZ 855 flag. Exceptions handlers must be wr 846 flag. Exceptions handlers must be wrapped as well. Irqs are already 856 protected inside ct_irq_enter/ct_irq 847 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal 857 handling on irq exit still need to b 848 handling on irq exit still need to be protected. 858 849 859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 850 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 860 bool 851 bool 861 help 852 help 862 Architecture neither relies on excep 853 Architecture neither relies on exception_enter()/exception_exit() 863 nor on schedule_user(). Also preempt 854 nor on schedule_user(). Also preempt_schedule_notrace() and 864 preempt_schedule_irq() can't be call 855 preempt_schedule_irq() can't be called in a preemptible section 865 while context tracking is CONTEXT_US 856 while context tracking is CONTEXT_USER. This feature reflects a sane 866 entry implementation where the follo 857 entry implementation where the following requirements are met on 867 critical entry code, ie: before user 858 critical entry code, ie: before user_exit() or after user_enter(): 868 859 869 - Critical entry code isn't preempti 860 - Critical entry code isn't preemptible (or better yet: 870 not interruptible). 861 not interruptible). 871 - No use of RCU read side critical s 862 - No use of RCU read side critical sections, unless ct_nmi_enter() 872 got called. 863 got called. 873 - No use of instrumentation, unless 864 - No use of instrumentation, unless instrumentation_begin() got 874 called. 865 called. 875 866 876 config HAVE_TIF_NOHZ 867 config HAVE_TIF_NOHZ 877 bool 868 bool 878 help 869 help 879 Arch relies on TIF_NOHZ and syscall 870 Arch relies on TIF_NOHZ and syscall slow path to implement context 880 tracking calls to user_enter()/user_ 871 tracking calls to user_enter()/user_exit(). 881 872 882 config HAVE_VIRT_CPU_ACCOUNTING 873 config HAVE_VIRT_CPU_ACCOUNTING 883 bool 874 bool 884 875 885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 876 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 886 bool 877 bool 887 help 878 help 888 Architecture has its own way to acco 879 Architecture has its own way to account idle CPU time and therefore 889 doesn't implement vtime_account_idle 880 doesn't implement vtime_account_idle(). 890 881 891 config ARCH_HAS_SCALED_CPUTIME 882 config ARCH_HAS_SCALED_CPUTIME 892 bool 883 bool 893 884 894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 885 config HAVE_VIRT_CPU_ACCOUNTING_GEN 895 bool 886 bool 896 default y if 64BIT 887 default y if 64BIT 897 help 888 help 898 With VIRT_CPU_ACCOUNTING_GEN, cputim 889 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 899 Before enabling this option, arch co 890 Before enabling this option, arch code must be audited 900 to ensure there are no races in conc 891 to ensure there are no races in concurrent read/write of 901 cputime_t. For example, reading/writ 892 cputime_t. For example, reading/writing 64-bit cputime_t on 902 some 32-bit arches may require multi 893 some 32-bit arches may require multiple accesses, so proper 903 locking is needed to protect against 894 locking is needed to protect against concurrent accesses. 904 895 905 config HAVE_IRQ_TIME_ACCOUNTING 896 config HAVE_IRQ_TIME_ACCOUNTING 906 bool 897 bool 907 help 898 help 908 Archs need to ensure they use a high 899 Archs need to ensure they use a high enough resolution clock to 909 support irq time accounting and then 900 support irq time accounting and then call enable_sched_clock_irqtime(). 910 901 911 config HAVE_MOVE_PUD 902 config HAVE_MOVE_PUD 912 bool 903 bool 913 help 904 help 914 Architectures that select this are a 905 Architectures that select this are able to move page tables at the 915 PUD level. If there are only 3 page 906 PUD level. If there are only 3 page table levels, the move effectively 916 happens at the PGD level. 907 happens at the PGD level. 917 908 918 config HAVE_MOVE_PMD 909 config HAVE_MOVE_PMD 919 bool 910 bool 920 help 911 help 921 Archs that select this are able to m 912 Archs that select this are able to move page tables at the PMD level. 922 913 923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 914 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 924 bool 915 bool 925 916 926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 917 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 927 bool 918 bool 928 919 929 config HAVE_ARCH_HUGE_VMAP 920 config HAVE_ARCH_HUGE_VMAP 930 bool 921 bool 931 922 932 # 923 # 933 # Archs that select this would be capable of 924 # Archs that select this would be capable of PMD-sized vmaps (i.e., 934 # arch_vmap_pmd_supported() returns true). Th 925 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag 935 # must be used to enable allocations to use h 926 # must be used to enable allocations to use hugepages. 936 # 927 # 937 config HAVE_ARCH_HUGE_VMALLOC 928 config HAVE_ARCH_HUGE_VMALLOC 938 depends on HAVE_ARCH_HUGE_VMAP 929 depends on HAVE_ARCH_HUGE_VMAP 939 bool 930 bool 940 931 941 config ARCH_WANT_HUGE_PMD_SHARE 932 config ARCH_WANT_HUGE_PMD_SHARE 942 bool 933 bool 943 934 944 # Archs that want to use pmd_mkwrite on kernel 935 # Archs that want to use pmd_mkwrite on kernel memory need it defined even 945 # if there are no userspace memory management 936 # if there are no userspace memory management features that use it 946 config ARCH_WANT_KERNEL_PMD_MKWRITE 937 config ARCH_WANT_KERNEL_PMD_MKWRITE 947 bool 938 bool 948 939 949 config ARCH_WANT_PMD_MKWRITE 940 config ARCH_WANT_PMD_MKWRITE 950 def_bool TRANSPARENT_HUGEPAGE || ARCH_ 941 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE 951 942 952 config HAVE_ARCH_SOFT_DIRTY 943 config HAVE_ARCH_SOFT_DIRTY 953 bool 944 bool 954 945 955 config HAVE_MOD_ARCH_SPECIFIC 946 config HAVE_MOD_ARCH_SPECIFIC 956 bool 947 bool 957 help 948 help 958 The arch uses struct mod_arch_specif 949 The arch uses struct mod_arch_specific to store data. Many arches 959 just need a simple module loader wit 950 just need a simple module loader without arch specific data - those 960 should not enable this. 951 should not enable this. 961 952 962 config MODULES_USE_ELF_RELA 953 config MODULES_USE_ELF_RELA 963 bool 954 bool 964 help 955 help 965 Modules only use ELF RELA relocation 956 Modules only use ELF RELA relocations. Modules with ELF REL 966 relocations will give an error. 957 relocations will give an error. 967 958 968 config MODULES_USE_ELF_REL 959 config MODULES_USE_ELF_REL 969 bool 960 bool 970 help 961 help 971 Modules only use ELF REL relocations 962 Modules only use ELF REL relocations. Modules with ELF RELA 972 relocations will give an error. 963 relocations will give an error. 973 964 974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 965 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 975 bool 966 bool 976 help 967 help 977 For architectures like powerpc/32 wh 968 For architectures like powerpc/32 which have constraints on module 978 allocation and need to allocate modu 969 allocation and need to allocate module data outside of module area. 979 970 980 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 971 config HAVE_IRQ_EXIT_ON_IRQ_STACK 989 bool 972 bool 990 help 973 help 991 Architecture doesn't only execute th 974 Architecture doesn't only execute the irq handler on the irq stack 992 but also irq_exit(). This way we can 975 but also irq_exit(). This way we can process softirqs on this irq 993 stack instead of switching to a new 976 stack instead of switching to a new one when we call __do_softirq() 994 in the end of an hardirq. 977 in the end of an hardirq. 995 This spares a stack switch and impro 978 This spares a stack switch and improves cache usage on softirq 996 processing. 979 processing. 997 980 998 config HAVE_SOFTIRQ_ON_OWN_STACK 981 config HAVE_SOFTIRQ_ON_OWN_STACK 999 bool 982 bool 1000 help 983 help 1001 Architecture provides a function to 984 Architecture provides a function to run __do_softirq() on a 1002 separate stack. 985 separate stack. 1003 986 1004 config SOFTIRQ_ON_OWN_STACK 987 config SOFTIRQ_ON_OWN_STACK 1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 988 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT 1006 989 1007 config ALTERNATE_USER_ADDRESS_SPACE 990 config ALTERNATE_USER_ADDRESS_SPACE 1008 bool 991 bool 1009 help 992 help 1010 Architectures set this when the CPU 993 Architectures set this when the CPU uses separate address 1011 spaces for kernel and user space po 994 spaces for kernel and user space pointers. In this case, the 1012 access_ok() check on a __user point 995 access_ok() check on a __user pointer is skipped. 1013 996 1014 config PGTABLE_LEVELS 997 config PGTABLE_LEVELS 1015 int 998 int 1016 default 2 999 default 2 1017 1000 1018 config ARCH_HAS_ELF_RANDOMIZE 1001 config ARCH_HAS_ELF_RANDOMIZE 1019 bool 1002 bool 1020 help 1003 help 1021 An architecture supports choosing r 1004 An architecture supports choosing randomized locations for 1022 stack, mmap, brk, and ET_DYN. Defin 1005 stack, mmap, brk, and ET_DYN. Defined functions: 1023 - arch_mmap_rnd() 1006 - arch_mmap_rnd() 1024 - arch_randomize_brk() 1007 - arch_randomize_brk() 1025 1008 1026 config HAVE_ARCH_MMAP_RND_BITS 1009 config HAVE_ARCH_MMAP_RND_BITS 1027 bool 1010 bool 1028 help 1011 help 1029 An arch should select this symbol i 1012 An arch should select this symbol if it supports setting a variable 1030 number of bits for use in establish 1013 number of bits for use in establishing the base address for mmap 1031 allocations, has MMU enabled and pr 1014 allocations, has MMU enabled and provides values for both: 1032 - ARCH_MMAP_RND_BITS_MIN 1015 - ARCH_MMAP_RND_BITS_MIN 1033 - ARCH_MMAP_RND_BITS_MAX 1016 - ARCH_MMAP_RND_BITS_MAX 1034 1017 1035 config HAVE_EXIT_THREAD 1018 config HAVE_EXIT_THREAD 1036 bool 1019 bool 1037 help 1020 help 1038 An architecture implements exit_thr 1021 An architecture implements exit_thread. 1039 1022 1040 config ARCH_MMAP_RND_BITS_MIN 1023 config ARCH_MMAP_RND_BITS_MIN 1041 int 1024 int 1042 1025 1043 config ARCH_MMAP_RND_BITS_MAX 1026 config ARCH_MMAP_RND_BITS_MAX 1044 int 1027 int 1045 1028 1046 config ARCH_MMAP_RND_BITS_DEFAULT 1029 config ARCH_MMAP_RND_BITS_DEFAULT 1047 int 1030 int 1048 1031 1049 config ARCH_MMAP_RND_BITS 1032 config ARCH_MMAP_RND_BITS 1050 int "Number of bits to use for ASLR o 1033 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 1034 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1052 default ARCH_MMAP_RND_BITS_DEFAULT if 1035 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1053 default ARCH_MMAP_RND_BITS_MIN 1036 default ARCH_MMAP_RND_BITS_MIN 1054 depends on HAVE_ARCH_MMAP_RND_BITS 1037 depends on HAVE_ARCH_MMAP_RND_BITS 1055 help 1038 help 1056 This value can be used to select th 1039 This value can be used to select the number of bits to use to 1057 determine the random offset to the 1040 determine the random offset to the base address of vma regions 1058 resulting from mmap allocations. Th 1041 resulting from mmap allocations. This value will be bounded 1059 by the architecture's minimum and m 1042 by the architecture's minimum and maximum supported values. 1060 1043 1061 This value can be changed after boo 1044 This value can be changed after boot using the 1062 /proc/sys/vm/mmap_rnd_bits tunable 1045 /proc/sys/vm/mmap_rnd_bits tunable 1063 1046 1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1047 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1065 bool 1048 bool 1066 help 1049 help 1067 An arch should select this symbol i 1050 An arch should select this symbol if it supports running applications 1068 in compatibility mode, supports set 1051 in compatibility mode, supports setting a variable number of bits for 1069 use in establishing the base addres 1052 use in establishing the base address for mmap allocations, has MMU 1070 enabled and provides values for bot 1053 enabled and provides values for both: 1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1054 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1055 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1073 1056 1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1057 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1075 int 1058 int 1076 1059 1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1060 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1078 int 1061 int 1079 1062 1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1063 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1081 int 1064 int 1082 1065 1083 config ARCH_MMAP_RND_COMPAT_BITS 1066 config ARCH_MMAP_RND_COMPAT_BITS 1084 int "Number of bits to use for ASLR o 1067 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 1068 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1069 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1070 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1071 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1089 help 1072 help 1090 This value can be used to select th 1073 This value can be used to select the number of bits to use to 1091 determine the random offset to the 1074 determine the random offset to the base address of vma regions 1092 resulting from mmap allocations for 1075 resulting from mmap allocations for compatible applications This 1093 value will be bounded by the archit 1076 value will be bounded by the architecture's minimum and maximum 1094 supported values. 1077 supported values. 1095 1078 1096 This value can be changed after boo 1079 This value can be changed after boot using the 1097 /proc/sys/vm/mmap_rnd_compat_bits t 1080 /proc/sys/vm/mmap_rnd_compat_bits tunable 1098 1081 1099 config HAVE_ARCH_COMPAT_MMAP_BASES 1082 config HAVE_ARCH_COMPAT_MMAP_BASES 1100 bool 1083 bool 1101 help 1084 help 1102 This allows 64bit applications to i 1085 This allows 64bit applications to invoke 32-bit mmap() syscall 1103 and vice-versa 32-bit applications 1086 and vice-versa 32-bit applications to call 64-bit mmap(). 1104 Required for applications doing dif 1087 Required for applications doing different bitness syscalls. 1105 1088 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 1089 config PAGE_SIZE_LESS_THAN_64KB 1190 def_bool y 1090 def_bool y >> 1091 depends on !ARM64_64K_PAGES 1191 depends on !PAGE_SIZE_64KB 1092 depends on !PAGE_SIZE_64KB >> 1093 depends on !PARISC_PAGE_SIZE_64KB 1192 depends on PAGE_SIZE_LESS_THAN_256KB 1094 depends on PAGE_SIZE_LESS_THAN_256KB 1193 1095 1194 config PAGE_SIZE_LESS_THAN_256KB 1096 config PAGE_SIZE_LESS_THAN_256KB 1195 def_bool y 1097 def_bool y 1196 depends on !PAGE_SIZE_256KB 1098 depends on !PAGE_SIZE_256KB 1197 1099 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 1100 # This allows to use a set of generic functions to determine mmap base 1208 # address by giving priority to top-down sche 1101 # address by giving priority to top-down scheme only if the process 1209 # is not in legacy mode (compat task, unlimit 1102 # is not in legacy mode (compat task, unlimited stack size or 1210 # sysctl_legacy_va_layout). 1103 # sysctl_legacy_va_layout). 1211 # Architecture that selects this option can p 1104 # Architecture that selects this option can provide its own version of: 1212 # - STACK_RND_MASK 1105 # - STACK_RND_MASK 1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1106 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1214 bool 1107 bool 1215 depends on MMU 1108 depends on MMU 1216 select ARCH_HAS_ELF_RANDOMIZE 1109 select ARCH_HAS_ELF_RANDOMIZE 1217 1110 1218 config HAVE_OBJTOOL 1111 config HAVE_OBJTOOL 1219 bool 1112 bool 1220 1113 1221 config HAVE_JUMP_LABEL_HACK 1114 config HAVE_JUMP_LABEL_HACK 1222 bool 1115 bool 1223 1116 1224 config HAVE_NOINSTR_HACK 1117 config HAVE_NOINSTR_HACK 1225 bool 1118 bool 1226 1119 1227 config HAVE_NOINSTR_VALIDATION 1120 config HAVE_NOINSTR_VALIDATION 1228 bool 1121 bool 1229 1122 1230 config HAVE_UACCESS_VALIDATION 1123 config HAVE_UACCESS_VALIDATION 1231 bool 1124 bool 1232 select OBJTOOL 1125 select OBJTOOL 1233 1126 1234 config HAVE_STACK_VALIDATION 1127 config HAVE_STACK_VALIDATION 1235 bool 1128 bool 1236 help 1129 help 1237 Architecture supports objtool compi 1130 Architecture supports objtool compile-time frame pointer rule 1238 validation. 1131 validation. 1239 1132 1240 config HAVE_RELIABLE_STACKTRACE 1133 config HAVE_RELIABLE_STACKTRACE 1241 bool 1134 bool 1242 help 1135 help 1243 Architecture has either save_stack_ 1136 Architecture has either save_stack_trace_tsk_reliable() or 1244 arch_stack_walk_reliable() function 1137 arch_stack_walk_reliable() function which only returns a stack trace 1245 if it can guarantee the trace is re 1138 if it can guarantee the trace is reliable. 1246 1139 1247 config HAVE_ARCH_HASH 1140 config HAVE_ARCH_HASH 1248 bool 1141 bool 1249 default n 1142 default n 1250 help 1143 help 1251 If this is set, the architecture pr 1144 If this is set, the architecture provides an <asm/hash.h> 1252 file which provides platform-specif 1145 file which provides platform-specific implementations of some 1253 functions in <linux/hash.h> or fs/n 1146 functions in <linux/hash.h> or fs/namei.c. 1254 1147 1255 config HAVE_ARCH_NVRAM_OPS 1148 config HAVE_ARCH_NVRAM_OPS 1256 bool 1149 bool 1257 1150 1258 config ISA_BUS_API 1151 config ISA_BUS_API 1259 def_bool ISA 1152 def_bool ISA 1260 1153 1261 # 1154 # 1262 # ABI hall of shame 1155 # ABI hall of shame 1263 # 1156 # 1264 config CLONE_BACKWARDS 1157 config CLONE_BACKWARDS 1265 bool 1158 bool 1266 help 1159 help 1267 Architecture has tls passed as the 1160 Architecture has tls passed as the 4th argument of clone(2), 1268 not the 5th one. 1161 not the 5th one. 1269 1162 1270 config CLONE_BACKWARDS2 1163 config CLONE_BACKWARDS2 1271 bool 1164 bool 1272 help 1165 help 1273 Architecture has the first two argu 1166 Architecture has the first two arguments of clone(2) swapped. 1274 1167 1275 config CLONE_BACKWARDS3 1168 config CLONE_BACKWARDS3 1276 bool 1169 bool 1277 help 1170 help 1278 Architecture has tls passed as the 1171 Architecture has tls passed as the 3rd argument of clone(2), 1279 not the 5th one. 1172 not the 5th one. 1280 1173 1281 config ODD_RT_SIGACTION 1174 config ODD_RT_SIGACTION 1282 bool 1175 bool 1283 help 1176 help 1284 Architecture has unusual rt_sigacti 1177 Architecture has unusual rt_sigaction(2) arguments 1285 1178 1286 config OLD_SIGSUSPEND 1179 config OLD_SIGSUSPEND 1287 bool 1180 bool 1288 help 1181 help 1289 Architecture has old sigsuspend(2) 1182 Architecture has old sigsuspend(2) syscall, of one-argument variety 1290 1183 1291 config OLD_SIGSUSPEND3 1184 config OLD_SIGSUSPEND3 1292 bool 1185 bool 1293 help 1186 help 1294 Even weirder antique ABI - three-ar 1187 Even weirder antique ABI - three-argument sigsuspend(2) 1295 1188 1296 config OLD_SIGACTION 1189 config OLD_SIGACTION 1297 bool 1190 bool 1298 help 1191 help 1299 Architecture has old sigaction(2) s 1192 Architecture has old sigaction(2) syscall. Nope, not the same 1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1193 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1301 but fairly different variant of sig 1194 but fairly different variant of sigaction(2), thanks to OSF/1 1302 compatibility... 1195 compatibility... 1303 1196 1304 config COMPAT_OLD_SIGACTION 1197 config COMPAT_OLD_SIGACTION 1305 bool 1198 bool 1306 1199 1307 config COMPAT_32BIT_TIME 1200 config COMPAT_32BIT_TIME 1308 bool "Provide system calls for 32-bit 1201 bool "Provide system calls for 32-bit time_t" 1309 default !64BIT || COMPAT 1202 default !64BIT || COMPAT 1310 help 1203 help 1311 This enables 32 bit time_t support 1204 This enables 32 bit time_t support in addition to 64 bit time_t support. 1312 This is relevant on all 32-bit arch 1205 This is relevant on all 32-bit architectures, and 64-bit architectures 1313 as part of compat syscall handling. 1206 as part of compat syscall handling. 1314 1207 1315 config ARCH_NO_PREEMPT 1208 config ARCH_NO_PREEMPT 1316 bool 1209 bool 1317 1210 1318 config ARCH_SUPPORTS_RT 1211 config ARCH_SUPPORTS_RT 1319 bool 1212 bool 1320 1213 1321 config CPU_NO_EFFICIENT_FFS 1214 config CPU_NO_EFFICIENT_FFS 1322 def_bool n 1215 def_bool n 1323 1216 1324 config HAVE_ARCH_VMAP_STACK 1217 config HAVE_ARCH_VMAP_STACK 1325 def_bool n 1218 def_bool n 1326 help 1219 help 1327 An arch should select this symbol i 1220 An arch should select this symbol if it can support kernel stacks 1328 in vmalloc space. This means: 1221 in vmalloc space. This means: 1329 1222 1330 - vmalloc space must be large enoug 1223 - vmalloc space must be large enough to hold many kernel stacks. 1331 This may rule out many 32-bit arc 1224 This may rule out many 32-bit architectures. 1332 1225 1333 - Stacks in vmalloc space need to w 1226 - Stacks in vmalloc space need to work reliably. For example, if 1334 vmap page tables are created on d 1227 vmap page tables are created on demand, either this mechanism 1335 needs to work while the stack poi 1228 needs to work while the stack points to a virtual address with 1336 unpopulated page tables or arch c 1229 unpopulated page tables or arch code (switch_to() and switch_mm(), 1337 most likely) needs to ensure that 1230 most likely) needs to ensure that the stack's page table entries 1338 are populated before running on a 1231 are populated before running on a possibly unpopulated stack. 1339 1232 1340 - If the stack overflows into a gua 1233 - If the stack overflows into a guard page, something reasonable 1341 should happen. The definition of 1234 should happen. The definition of "reasonable" is flexible, but 1342 instantly rebooting without loggi 1235 instantly rebooting without logging anything would be unfriendly. 1343 1236 1344 config VMAP_STACK 1237 config VMAP_STACK 1345 default y 1238 default y 1346 bool "Use a virtually-mapped stack" 1239 bool "Use a virtually-mapped stack" 1347 depends on HAVE_ARCH_VMAP_STACK 1240 depends on HAVE_ARCH_VMAP_STACK 1348 depends on !KASAN || KASAN_HW_TAGS || 1241 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1349 help 1242 help 1350 Enable this if you want the use vir 1243 Enable this if you want the use virtually-mapped kernel stacks 1351 with guard pages. This causes kern 1244 with guard pages. This causes kernel stack overflows to be 1352 caught immediately rather than caus 1245 caught immediately rather than causing difficult-to-diagnose 1353 corruption. 1246 corruption. 1354 1247 1355 To use this with software KASAN mod 1248 To use this with software KASAN modes, the architecture must support 1356 backing virtual mappings with real 1249 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1357 must be enabled. 1250 must be enabled. 1358 1251 1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1252 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1360 def_bool n 1253 def_bool n 1361 help 1254 help 1362 An arch should select this symbol i 1255 An arch should select this symbol if it can support kernel stack 1363 offset randomization with calls to 1256 offset randomization with calls to add_random_kstack_offset() 1364 during syscall entry and choose_ran 1257 during syscall entry and choose_random_kstack_offset() during 1365 syscall exit. Careful removal of -f 1258 syscall exit. Careful removal of -fstack-protector-strong and 1366 -fstack-protector should also be ap 1259 -fstack-protector should also be applied to the entry code and 1367 closely examined, as the artificial 1260 closely examined, as the artificial stack bump looks like an array 1368 to the compiler, so it will attempt 1261 to the compiler, so it will attempt to add canary checks regardless 1369 of the static branch state. 1262 of the static branch state. 1370 1263 1371 config RANDOMIZE_KSTACK_OFFSET 1264 config RANDOMIZE_KSTACK_OFFSET 1372 bool "Support for randomizing kernel 1265 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT 1373 default y 1266 default y 1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1267 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1375 depends on INIT_STACK_NONE || !CC_IS_ 1268 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 1376 help 1269 help 1377 The kernel stack offset can be rand 1270 The kernel stack offset can be randomized (after pt_regs) by 1378 roughly 5 bits of entropy, frustrat 1271 roughly 5 bits of entropy, frustrating memory corruption 1379 attacks that depend on stack addres 1272 attacks that depend on stack address determinism or 1380 cross-syscall address exposures. 1273 cross-syscall address exposures. 1381 1274 1382 The feature is controlled via the " 1275 The feature is controlled via the "randomize_kstack_offset=on/off" 1383 kernel boot param, and if turned of 1276 kernel boot param, and if turned off has zero overhead due to its use 1384 of static branches (see JUMP_LABEL) 1277 of static branches (see JUMP_LABEL). 1385 1278 1386 If unsure, say Y. 1279 If unsure, say Y. 1387 1280 1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1281 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1389 bool "Default state of kernel stack o 1282 bool "Default state of kernel stack offset randomization" 1390 depends on RANDOMIZE_KSTACK_OFFSET 1283 depends on RANDOMIZE_KSTACK_OFFSET 1391 help 1284 help 1392 Kernel stack offset randomization i 1285 Kernel stack offset randomization is controlled by kernel boot param 1393 "randomize_kstack_offset=on/off", a 1286 "randomize_kstack_offset=on/off", and this config chooses the default 1394 boot state. 1287 boot state. 1395 1288 1396 config ARCH_OPTIONAL_KERNEL_RWX 1289 config ARCH_OPTIONAL_KERNEL_RWX 1397 def_bool n 1290 def_bool n 1398 1291 1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1292 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1400 def_bool n 1293 def_bool n 1401 1294 1402 config ARCH_HAS_STRICT_KERNEL_RWX 1295 config ARCH_HAS_STRICT_KERNEL_RWX 1403 def_bool n 1296 def_bool n 1404 1297 1405 config STRICT_KERNEL_RWX 1298 config STRICT_KERNEL_RWX 1406 bool "Make kernel text and rodata rea 1299 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1300 depends on ARCH_HAS_STRICT_KERNEL_RWX 1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1301 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1409 help 1302 help 1410 If this is set, kernel text and rod 1303 If this is set, kernel text and rodata memory will be made read-only, 1411 and non-text memory will be made no 1304 and non-text memory will be made non-executable. This provides 1412 protection against certain security 1305 protection against certain security exploits (e.g. executing the heap 1413 or modifying text) 1306 or modifying text) 1414 1307 1415 These features are considered stand 1308 These features are considered standard security practice these days. 1416 You should say Y here in almost all 1309 You should say Y here in almost all cases. 1417 1310 1418 config ARCH_HAS_STRICT_MODULE_RWX 1311 config ARCH_HAS_STRICT_MODULE_RWX 1419 def_bool n 1312 def_bool n 1420 1313 1421 config STRICT_MODULE_RWX 1314 config STRICT_MODULE_RWX 1422 bool "Set loadable kernel module data 1315 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 1316 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1317 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1425 help 1318 help 1426 If this is set, module text and rod 1319 If this is set, module text and rodata memory will be made read-only, 1427 and non-text memory will be made no 1320 and non-text memory will be made non-executable. This provides 1428 protection against certain security 1321 protection against certain security exploits (e.g. writing to text) 1429 1322 1430 # select if the architecture provides an asm/ 1323 # select if the architecture provides an asm/dma-direct.h header 1431 config ARCH_HAS_PHYS_TO_DMA 1324 config ARCH_HAS_PHYS_TO_DMA 1432 bool 1325 bool 1433 1326 1434 config HAVE_ARCH_COMPILER_H 1327 config HAVE_ARCH_COMPILER_H 1435 bool 1328 bool 1436 help 1329 help 1437 An architecture can select this if 1330 An architecture can select this if it provides an 1438 asm/compiler.h header that should b 1331 asm/compiler.h header that should be included after 1439 linux/compiler-*.h in order to over 1332 linux/compiler-*.h in order to override macro definitions that those 1440 headers generally provide. 1333 headers generally provide. 1441 1334 1442 config HAVE_ARCH_PREL32_RELOCATIONS 1335 config HAVE_ARCH_PREL32_RELOCATIONS 1443 bool 1336 bool 1444 help 1337 help 1445 May be selected by an architecture 1338 May be selected by an architecture if it supports place-relative 1446 32-bit relocations, both in the too 1339 32-bit relocations, both in the toolchain and in the module loader, 1447 in which case relative references c 1340 in which case relative references can be used in special sections 1448 for PCI fixup, initcalls etc which 1341 for PCI fixup, initcalls etc which are only half the size on 64 bit 1449 architectures, and don't require ru 1342 architectures, and don't require runtime relocation on relocatable 1450 kernels. 1343 kernels. 1451 1344 1452 config ARCH_USE_MEMREMAP_PROT 1345 config ARCH_USE_MEMREMAP_PROT 1453 bool 1346 bool 1454 1347 1455 config LOCK_EVENT_COUNTS 1348 config LOCK_EVENT_COUNTS 1456 bool "Locking event counts collection 1349 bool "Locking event counts collection" 1457 depends on DEBUG_FS 1350 depends on DEBUG_FS 1458 help 1351 help 1459 Enable light-weight counting of var 1352 Enable light-weight counting of various locking related events 1460 in the system with minimal performa 1353 in the system with minimal performance impact. This reduces 1461 the chance of application behavior 1354 the chance of application behavior change because of timing 1462 differences. The counts are reporte 1355 differences. The counts are reported via debugfs. 1463 1356 1464 # Select if the architecture has support for 1357 # Select if the architecture has support for applying RELR relocations. 1465 config ARCH_HAS_RELR 1358 config ARCH_HAS_RELR 1466 bool 1359 bool 1467 1360 1468 config RELR 1361 config RELR 1469 bool "Use RELR relocation packing" 1362 bool "Use RELR relocation packing" 1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1363 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1471 default y 1364 default y 1472 help 1365 help 1473 Store the kernel's dynamic relocati 1366 Store the kernel's dynamic relocations in the RELR relocation packing 1474 format. Requires a compatible linke 1367 format. Requires a compatible linker (LLD supports this feature), as 1475 well as compatible NM and OBJCOPY u 1368 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1476 are compatible). 1369 are compatible). 1477 1370 1478 config ARCH_HAS_MEM_ENCRYPT 1371 config ARCH_HAS_MEM_ENCRYPT 1479 bool 1372 bool 1480 1373 1481 config ARCH_HAS_CC_PLATFORM 1374 config ARCH_HAS_CC_PLATFORM 1482 bool 1375 bool 1483 1376 1484 config HAVE_SPARSE_SYSCALL_NR 1377 config HAVE_SPARSE_SYSCALL_NR 1485 bool 1378 bool 1486 help 1379 help 1487 An architecture should select this 1380 An architecture should select this if its syscall numbering is sparse 1488 to save space. For example, MIPS ar 1381 to save space. For example, MIPS architecture has a syscall array with 1489 entries at 4000, 5000 and 6000 loca 1382 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1490 related optimizations for a given a 1383 related optimizations for a given architecture. 1491 1384 1492 config ARCH_HAS_VDSO_DATA 1385 config ARCH_HAS_VDSO_DATA 1493 bool 1386 bool 1494 1387 1495 config HAVE_STATIC_CALL 1388 config HAVE_STATIC_CALL 1496 bool 1389 bool 1497 1390 1498 config HAVE_STATIC_CALL_INLINE 1391 config HAVE_STATIC_CALL_INLINE 1499 bool 1392 bool 1500 depends on HAVE_STATIC_CALL 1393 depends on HAVE_STATIC_CALL 1501 select OBJTOOL 1394 select OBJTOOL 1502 1395 1503 config HAVE_PREEMPT_DYNAMIC 1396 config HAVE_PREEMPT_DYNAMIC 1504 bool 1397 bool 1505 1398 1506 config HAVE_PREEMPT_DYNAMIC_CALL 1399 config HAVE_PREEMPT_DYNAMIC_CALL 1507 bool 1400 bool 1508 depends on HAVE_STATIC_CALL 1401 depends on HAVE_STATIC_CALL 1509 select HAVE_PREEMPT_DYNAMIC 1402 select HAVE_PREEMPT_DYNAMIC 1510 help 1403 help 1511 An architecture should select this 1404 An architecture should select this if it can handle the preemption 1512 model being selected at boot time u 1405 model being selected at boot time using static calls. 1513 1406 1514 Where an architecture selects HAVE_ 1407 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a 1515 preemption function will be patched 1408 preemption function will be patched directly. 1516 1409 1517 Where an architecture does not sele 1410 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any 1518 call to a preemption function will 1411 call to a preemption function will go through a trampoline, and the 1519 trampoline will be patched. 1412 trampoline will be patched. 1520 1413 1521 It is strongly advised to support i 1414 It is strongly advised to support inline static call to avoid any 1522 overhead. 1415 overhead. 1523 1416 1524 config HAVE_PREEMPT_DYNAMIC_KEY 1417 config HAVE_PREEMPT_DYNAMIC_KEY 1525 bool 1418 bool 1526 depends on HAVE_ARCH_JUMP_LABEL 1419 depends on HAVE_ARCH_JUMP_LABEL 1527 select HAVE_PREEMPT_DYNAMIC 1420 select HAVE_PREEMPT_DYNAMIC 1528 help 1421 help 1529 An architecture should select this 1422 An architecture should select this if it can handle the preemption 1530 model being selected at boot time u 1423 model being selected at boot time using static keys. 1531 1424 1532 Each preemption function will be gi 1425 Each preemption function will be given an early return based on a 1533 static key. This should have slight 1426 static key. This should have slightly lower overhead than non-inline 1534 static calls, as this effectively i 1427 static calls, as this effectively inlines each trampoline into the 1535 start of its callee. This may avoid 1428 start of its callee. This may avoid redundant work, and may 1536 integrate better with CFI schemes. 1429 integrate better with CFI schemes. 1537 1430 1538 This will have greater overhead tha 1431 This will have greater overhead than using inline static calls as 1539 the call to the preemption function 1432 the call to the preemption function cannot be entirely elided. 1540 1433 1541 config ARCH_WANT_LD_ORPHAN_WARN 1434 config ARCH_WANT_LD_ORPHAN_WARN 1542 bool 1435 bool 1543 help 1436 help 1544 An arch should select this symbol o 1437 An arch should select this symbol once all linker sections are explicitly 1545 included, size-asserted, or discard 1438 included, size-asserted, or discarded in the linker scripts. This is 1546 important because we never want exp 1439 important because we never want expected sections to be placed heuristically 1547 by the linker, since the locations 1440 by the linker, since the locations of such sections can change between linker 1548 versions. 1441 versions. 1549 1442 1550 config HAVE_ARCH_PFN_VALID 1443 config HAVE_ARCH_PFN_VALID 1551 bool 1444 bool 1552 1445 1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1446 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1554 bool 1447 bool 1555 1448 1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1449 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1557 bool 1450 bool 1558 1451 1559 config ARCH_SPLIT_ARG64 1452 config ARCH_SPLIT_ARG64 1560 bool 1453 bool 1561 help 1454 help 1562 If a 32-bit architecture requires 6 1455 If a 32-bit architecture requires 64-bit arguments to be split into 1563 pairs of 32-bit arguments, select t 1456 pairs of 32-bit arguments, select this option. 1564 1457 1565 config ARCH_HAS_ELFCORE_COMPAT 1458 config ARCH_HAS_ELFCORE_COMPAT 1566 bool 1459 bool 1567 1460 1568 config ARCH_HAS_PARANOID_L1D_FLUSH 1461 config ARCH_HAS_PARANOID_L1D_FLUSH 1569 bool 1462 bool 1570 1463 1571 config ARCH_HAVE_TRACE_MMIO_ACCESS 1464 config ARCH_HAVE_TRACE_MMIO_ACCESS 1572 bool 1465 bool 1573 1466 1574 config DYNAMIC_SIGFRAME 1467 config DYNAMIC_SIGFRAME 1575 bool 1468 bool 1576 1469 1577 # Select, if arch has a named attribute group 1470 # Select, if arch has a named attribute group bound to NUMA device nodes. 1578 config HAVE_ARCH_NODE_DEV_GROUP 1471 config HAVE_ARCH_NODE_DEV_GROUP 1579 bool 1472 bool 1580 1473 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 1474 config ARCH_HAS_NONLEAF_PMD_YOUNG 1590 bool 1475 bool 1591 help 1476 help 1592 Architectures that select this opti 1477 Architectures that select this option are capable of setting the 1593 accessed bit in non-leaf PMD entrie 1478 accessed bit in non-leaf PMD entries when using them as part of linear 1594 address translations. Page table wa 1479 address translations. Page table walkers that clear the accessed bit 1595 may use this capability to reduce t 1480 may use this capability to reduce their search space. 1596 1481 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" 1482 source "kernel/gcov/Kconfig" 1604 1483 1605 source "scripts/gcc-plugins/Kconfig" 1484 source "scripts/gcc-plugins/Kconfig" 1606 1485 1607 config FUNCTION_ALIGNMENT_4B 1486 config FUNCTION_ALIGNMENT_4B 1608 bool 1487 bool 1609 1488 1610 config FUNCTION_ALIGNMENT_8B 1489 config FUNCTION_ALIGNMENT_8B 1611 bool 1490 bool 1612 1491 1613 config FUNCTION_ALIGNMENT_16B 1492 config FUNCTION_ALIGNMENT_16B 1614 bool 1493 bool 1615 1494 1616 config FUNCTION_ALIGNMENT_32B 1495 config FUNCTION_ALIGNMENT_32B 1617 bool 1496 bool 1618 1497 1619 config FUNCTION_ALIGNMENT_64B 1498 config FUNCTION_ALIGNMENT_64B 1620 bool 1499 bool 1621 1500 1622 config FUNCTION_ALIGNMENT 1501 config FUNCTION_ALIGNMENT 1623 int 1502 int 1624 default 64 if FUNCTION_ALIGNMENT_64B 1503 default 64 if FUNCTION_ALIGNMENT_64B 1625 default 32 if FUNCTION_ALIGNMENT_32B 1504 default 32 if FUNCTION_ALIGNMENT_32B 1626 default 16 if FUNCTION_ALIGNMENT_16B 1505 default 16 if FUNCTION_ALIGNMENT_16B 1627 default 8 if FUNCTION_ALIGNMENT_8B 1506 default 8 if FUNCTION_ALIGNMENT_8B 1628 default 4 if FUNCTION_ALIGNMENT_4B 1507 default 4 if FUNCTION_ALIGNMENT_4B 1629 default 0 1508 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 1509 1646 endmenu 1510 endmenu
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.