| 1 | # SPDX-License-Identifier: GPL-2.0 |
| 2 | # |
| 3 | # General architecture dependent options |
| 4 | # |
| 5 | |
| 6 | config CRASH_CORE |
| 7 | bool |
| 8 | |
| 9 | config KEXEC_CORE |
| 10 | select CRASH_CORE |
| 11 | bool |
| 12 | |
| 13 | config HAVE_IMA_KEXEC |
| 14 | bool |
| 15 | |
| 16 | config OPROFILE |
| 17 | tristate "OProfile system profiling" |
| 18 | depends on PROFILING |
| 19 | depends on HAVE_OPROFILE |
| 20 | select RING_BUFFER |
| 21 | select RING_BUFFER_ALLOW_SWAP |
| 22 | help |
| 23 | OProfile is a profiling system capable of profiling the |
| 24 | whole system, include the kernel, kernel modules, libraries, |
| 25 | and applications. |
| 26 | |
| 27 | If unsure, say N. |
| 28 | |
| 29 | config OPROFILE_EVENT_MULTIPLEX |
| 30 | bool "OProfile multiplexing support (EXPERIMENTAL)" |
| 31 | default n |
| 32 | depends on OPROFILE && X86 |
| 33 | help |
| 34 | The number of hardware counters is limited. The multiplexing |
| 35 | feature enables OProfile to gather more events than counters |
| 36 | are provided by the hardware. This is realized by switching |
| 37 | between events at a user specified time interval. |
| 38 | |
| 39 | If unsure, say N. |
| 40 | |
| 41 | config HAVE_OPROFILE |
| 42 | bool |
| 43 | |
| 44 | config OPROFILE_NMI_TIMER |
| 45 | def_bool y |
| 46 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
| 47 | |
| 48 | config KPROBES |
| 49 | bool "Kprobes" |
| 50 | depends on MODULES |
| 51 | depends on HAVE_KPROBES |
| 52 | select KALLSYMS |
| 53 | help |
| 54 | Kprobes allows you to trap at almost any kernel address and |
| 55 | execute a callback function. register_kprobe() establishes |
| 56 | a probepoint and specifies the callback. Kprobes is useful |
| 57 | for kernel debugging, non-intrusive instrumentation and testing. |
| 58 | If in doubt, say "N". |
| 59 | |
| 60 | config JUMP_LABEL |
| 61 | bool "Optimize very unlikely/likely branches" |
| 62 | depends on HAVE_ARCH_JUMP_LABEL |
| 63 | help |
| 64 | This option enables a transparent branch optimization that |
| 65 | makes certain almost-always-true or almost-always-false branch |
| 66 | conditions even cheaper to execute within the kernel. |
| 67 | |
| 68 | Certain performance-sensitive kernel code, such as trace points, |
| 69 | scheduler functionality, networking code and KVM have such |
| 70 | branches and include support for this optimization technique. |
| 71 | |
| 72 | If it is detected that the compiler has support for "asm goto", |
| 73 | the kernel will compile such branches with just a nop |
| 74 | instruction. When the condition flag is toggled to true, the |
| 75 | nop will be converted to a jump instruction to execute the |
| 76 | conditional block of instructions. |
| 77 | |
| 78 | This technique lowers overhead and stress on the branch prediction |
| 79 | of the processor and generally makes the kernel faster. The update |
| 80 | of the condition is slower, but those are always very rare. |
| 81 | |
| 82 | ( On 32-bit x86, the necessary options added to the compiler |
| 83 | flags may increase the size of the kernel slightly. ) |
| 84 | |
| 85 | config STATIC_KEYS_SELFTEST |
| 86 | bool "Static key selftest" |
| 87 | depends on JUMP_LABEL |
| 88 | help |
| 89 | Boot time self-test of the branch patching code. |
| 90 | |
| 91 | config OPTPROBES |
| 92 | def_bool y |
| 93 | depends on KPROBES && HAVE_OPTPROBES |
| 94 | select TASKS_RCU if PREEMPT |
| 95 | |
| 96 | config KPROBES_ON_FTRACE |
| 97 | def_bool y |
| 98 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE |
| 99 | depends on DYNAMIC_FTRACE_WITH_REGS |
| 100 | help |
| 101 | If function tracer is enabled and the arch supports full |
| 102 | passing of pt_regs to function tracing, then kprobes can |
| 103 | optimize on top of function tracing. |
| 104 | |
| 105 | config UPROBES |
| 106 | def_bool n |
| 107 | depends on ARCH_SUPPORTS_UPROBES |
| 108 | help |
| 109 | Uprobes is the user-space counterpart to kprobes: they |
| 110 | enable instrumentation applications (such as 'perf probe') |
| 111 | to establish unintrusive probes in user-space binaries and |
| 112 | libraries, by executing handler functions when the probes |
| 113 | are hit by user-space applications. |
| 114 | |
| 115 | ( These probes come in the form of single-byte breakpoints, |
| 116 | managed by the kernel and kept transparent to the probed |
| 117 | application. ) |
| 118 | |
| 119 | config HAVE_64BIT_ALIGNED_ACCESS |
| 120 | def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS |
| 121 | help |
| 122 | Some architectures require 64 bit accesses to be 64 bit |
| 123 | aligned, which also requires structs containing 64 bit values |
| 124 | to be 64 bit aligned too. This includes some 32 bit |
| 125 | architectures which can do 64 bit accesses, as well as 64 bit |
| 126 | architectures without unaligned access. |
| 127 | |
| 128 | This symbol should be selected by an architecture if 64 bit |
| 129 | accesses are required to be 64 bit aligned in this way even |
| 130 | though it is not a 64 bit architecture. |
| 131 | |
| 132 | See Documentation/unaligned-memory-access.txt for more |
| 133 | information on the topic of unaligned memory accesses. |
| 134 | |
| 135 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
| 136 | bool |
| 137 | help |
| 138 | Some architectures are unable to perform unaligned accesses |
| 139 | without the use of get_unaligned/put_unaligned. Others are |
| 140 | unable to perform such accesses efficiently (e.g. trap on |
| 141 | unaligned access and require fixing it up in the exception |
| 142 | handler.) |
| 143 | |
| 144 | This symbol should be selected by an architecture if it can |
| 145 | perform unaligned accesses efficiently to allow different |
| 146 | code paths to be selected for these cases. Some network |
| 147 | drivers, for example, could opt to not fix up alignment |
| 148 | problems with received packets if doing so would not help |
| 149 | much. |
| 150 | |
| 151 | See Documentation/unaligned-memory-access.txt for more |
| 152 | information on the topic of unaligned memory accesses. |
| 153 | |
| 154 | config ARCH_USE_BUILTIN_BSWAP |
| 155 | bool |
| 156 | help |
| 157 | Modern versions of GCC (since 4.4) have builtin functions |
| 158 | for handling byte-swapping. Using these, instead of the old |
| 159 | inline assembler that the architecture code provides in the |
| 160 | __arch_bswapXX() macros, allows the compiler to see what's |
| 161 | happening and offers more opportunity for optimisation. In |
| 162 | particular, the compiler will be able to combine the byteswap |
| 163 | with a nearby load or store and use load-and-swap or |
| 164 | store-and-swap instructions if the architecture has them. It |
| 165 | should almost *never* result in code which is worse than the |
| 166 | hand-coded assembler in <asm/swab.h>. But just in case it |
| 167 | does, the use of the builtins is optional. |
| 168 | |
| 169 | Any architecture with load-and-swap or store-and-swap |
| 170 | instructions should set this. And it shouldn't hurt to set it |
| 171 | on architectures that don't have such instructions. |
| 172 | |
| 173 | config KRETPROBES |
| 174 | def_bool y |
| 175 | depends on KPROBES && HAVE_KRETPROBES |
| 176 | |
| 177 | config USER_RETURN_NOTIFIER |
| 178 | bool |
| 179 | depends on HAVE_USER_RETURN_NOTIFIER |
| 180 | help |
| 181 | Provide a kernel-internal notification when a cpu is about to |
| 182 | switch to user mode. |
| 183 | |
| 184 | config HAVE_IOREMAP_PROT |
| 185 | bool |
| 186 | |
| 187 | config HAVE_KPROBES |
| 188 | bool |
| 189 | |
| 190 | config HAVE_KRETPROBES |
| 191 | bool |
| 192 | |
| 193 | config HAVE_OPTPROBES |
| 194 | bool |
| 195 | |
| 196 | config HAVE_KPROBES_ON_FTRACE |
| 197 | bool |
| 198 | |
| 199 | config HAVE_FUNCTION_ERROR_INJECTION |
| 200 | bool |
| 201 | |
| 202 | config HAVE_NMI |
| 203 | bool |
| 204 | |
| 205 | # |
| 206 | # An arch should select this if it provides all these things: |
| 207 | # |
| 208 | # task_pt_regs() in asm/processor.h or asm/ptrace.h |
| 209 | # arch_has_single_step() if there is hardware single-step support |
| 210 | # arch_has_block_step() if there is hardware block-step support |
| 211 | # asm/syscall.h supplying asm-generic/syscall.h interface |
| 212 | # linux/regset.h user_regset interfaces |
| 213 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h |
| 214 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} |
| 215 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() |
| 216 | # signal delivery calls tracehook_signal_handler() |
| 217 | # |
| 218 | config HAVE_ARCH_TRACEHOOK |
| 219 | bool |
| 220 | |
| 221 | config HAVE_DMA_CONTIGUOUS |
| 222 | bool |
| 223 | |
| 224 | config GENERIC_SMP_IDLE_THREAD |
| 225 | bool |
| 226 | |
| 227 | config GENERIC_IDLE_POLL_SETUP |
| 228 | bool |
| 229 | |
| 230 | config ARCH_HAS_FORTIFY_SOURCE |
| 231 | bool |
| 232 | help |
| 233 | An architecture should select this when it can successfully |
| 234 | build and run with CONFIG_FORTIFY_SOURCE. |
| 235 | |
| 236 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
| 237 | config ARCH_HAS_SET_MEMORY |
| 238 | bool |
| 239 | |
| 240 | # Select if arch init_task must go in the __init_task_data section |
| 241 | config ARCH_TASK_STRUCT_ON_STACK |
| 242 | bool |
| 243 | |
| 244 | # Select if arch has its private alloc_task_struct() function |
| 245 | config ARCH_TASK_STRUCT_ALLOCATOR |
| 246 | bool |
| 247 | |
| 248 | config HAVE_ARCH_THREAD_STRUCT_WHITELIST |
| 249 | bool |
| 250 | depends on !ARCH_TASK_STRUCT_ALLOCATOR |
| 251 | help |
| 252 | An architecture should select this to provide hardened usercopy |
| 253 | knowledge about what region of the thread_struct should be |
| 254 | whitelisted for copying to userspace. Normally this is only the |
| 255 | FPU registers. Specifically, arch_thread_struct_whitelist() |
| 256 | should be implemented. Without this, the entire thread_struct |
| 257 | field in task_struct will be left whitelisted. |
| 258 | |
| 259 | # Select if arch has its private alloc_thread_stack() function |
| 260 | config ARCH_THREAD_STACK_ALLOCATOR |
| 261 | bool |
| 262 | |
| 263 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
| 264 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT |
| 265 | bool |
| 266 | |
| 267 | config HAVE_REGS_AND_STACK_ACCESS_API |
| 268 | bool |
| 269 | help |
| 270 | This symbol should be selected by an architecure if it supports |
| 271 | the API needed to access registers and stack entries from pt_regs, |
| 272 | declared in asm/ptrace.h |
| 273 | For example the kprobes-based event tracer needs this API. |
| 274 | |
| 275 | config HAVE_RSEQ |
| 276 | bool |
| 277 | depends on HAVE_REGS_AND_STACK_ACCESS_API |
| 278 | help |
| 279 | This symbol should be selected by an architecture if it |
| 280 | supports an implementation of restartable sequences. |
| 281 | |
| 282 | config HAVE_CLK |
| 283 | bool |
| 284 | help |
| 285 | The <linux/clk.h> calls support software clock gating and |
| 286 | thus are a key power management tool on many systems. |
| 287 | |
| 288 | config HAVE_HW_BREAKPOINT |
| 289 | bool |
| 290 | depends on PERF_EVENTS |
| 291 | |
| 292 | config HAVE_MIXED_BREAKPOINTS_REGS |
| 293 | bool |
| 294 | depends on HAVE_HW_BREAKPOINT |
| 295 | help |
| 296 | Depending on the arch implementation of hardware breakpoints, |
| 297 | some of them have separate registers for data and instruction |
| 298 | breakpoints addresses, others have mixed registers to store |
| 299 | them but define the access type in a control register. |
| 300 | Select this option if your arch implements breakpoints under the |
| 301 | latter fashion. |
| 302 | |
| 303 | config HAVE_USER_RETURN_NOTIFIER |
| 304 | bool |
| 305 | |
| 306 | config HAVE_PERF_EVENTS_NMI |
| 307 | bool |
| 308 | help |
| 309 | System hardware can generate an NMI using the perf event |
| 310 | subsystem. Also has support for calculating CPU cycle events |
| 311 | to determine how many clock cycles in a given period. |
| 312 | |
| 313 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
| 314 | bool |
| 315 | depends on HAVE_PERF_EVENTS_NMI |
| 316 | help |
| 317 | The arch chooses to use the generic perf-NMI-based hardlockup |
| 318 | detector. Must define HAVE_PERF_EVENTS_NMI. |
| 319 | |
| 320 | config HAVE_NMI_WATCHDOG |
| 321 | depends on HAVE_NMI |
| 322 | bool |
| 323 | help |
| 324 | The arch provides a low level NMI watchdog. It provides |
| 325 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). |
| 326 | |
| 327 | config HAVE_HARDLOCKUP_DETECTOR_ARCH |
| 328 | bool |
| 329 | select HAVE_NMI_WATCHDOG |
| 330 | help |
| 331 | The arch chooses to provide its own hardlockup detector, which is |
| 332 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config |
| 333 | interfaces and parameters provided by hardlockup detector subsystem. |
| 334 | |
| 335 | config HAVE_PERF_REGS |
| 336 | bool |
| 337 | help |
| 338 | Support selective register dumps for perf events. This includes |
| 339 | bit-mapping of each registers and a unique architecture id. |
| 340 | |
| 341 | config HAVE_PERF_USER_STACK_DUMP |
| 342 | bool |
| 343 | help |
| 344 | Support user stack dumps for perf event samples. This needs |
| 345 | access to the user stack pointer which is not unified across |
| 346 | architectures. |
| 347 | |
| 348 | config HAVE_ARCH_JUMP_LABEL |
| 349 | bool |
| 350 | |
| 351 | config HAVE_RCU_TABLE_FREE |
| 352 | bool |
| 353 | |
| 354 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
| 355 | bool |
| 356 | |
| 357 | config HAVE_ALIGNED_STRUCT_PAGE |
| 358 | bool |
| 359 | help |
| 360 | This makes sure that struct pages are double word aligned and that |
| 361 | e.g. the SLUB allocator can perform double word atomic operations |
| 362 | on a struct page for better performance. However selecting this |
| 363 | might increase the size of a struct page by a word. |
| 364 | |
| 365 | config HAVE_CMPXCHG_LOCAL |
| 366 | bool |
| 367 | |
| 368 | config HAVE_CMPXCHG_DOUBLE |
| 369 | bool |
| 370 | |
| 371 | config ARCH_WEAK_RELEASE_ACQUIRE |
| 372 | bool |
| 373 | |
| 374 | config ARCH_WANT_IPC_PARSE_VERSION |
| 375 | bool |
| 376 | |
| 377 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| 378 | bool |
| 379 | |
| 380 | config ARCH_WANT_OLD_COMPAT_IPC |
| 381 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| 382 | bool |
| 383 | |
| 384 | config HAVE_ARCH_SECCOMP_FILTER |
| 385 | bool |
| 386 | help |
| 387 | An arch should select this symbol if it provides all of these things: |
| 388 | - syscall_get_arch() |
| 389 | - syscall_get_arguments() |
| 390 | - syscall_rollback() |
| 391 | - syscall_set_return_value() |
| 392 | - SIGSYS siginfo_t support |
| 393 | - secure_computing is called from a ptrace_event()-safe context |
| 394 | - secure_computing return value is checked and a return value of -1 |
| 395 | results in the system call being skipped immediately. |
| 396 | - seccomp syscall wired up |
| 397 | |
| 398 | config SECCOMP_FILTER |
| 399 | def_bool y |
| 400 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET |
| 401 | help |
| 402 | Enable tasks to build secure computing environments defined |
| 403 | in terms of Berkeley Packet Filter programs which implement |
| 404 | task-defined system call filtering polices. |
| 405 | |
| 406 | See Documentation/userspace-api/seccomp_filter.rst for details. |
| 407 | |
| 408 | preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC)) |
| 409 | |
| 410 | config PLUGIN_HOSTCC |
| 411 | string |
| 412 | default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" |
| 413 | help |
| 414 | Host compiler used to build GCC plugins. This can be $(HOSTCXX), |
| 415 | $(HOSTCC), or a null string if GCC plugin is unsupported. |
| 416 | |
| 417 | config HAVE_GCC_PLUGINS |
| 418 | bool |
| 419 | help |
| 420 | An arch should select this symbol if it supports building with |
| 421 | GCC plugins. |
| 422 | |
| 423 | menuconfig GCC_PLUGINS |
| 424 | bool "GCC plugins" |
| 425 | depends on HAVE_GCC_PLUGINS |
| 426 | depends on PLUGIN_HOSTCC != "" |
| 427 | help |
| 428 | GCC plugins are loadable modules that provide extra features to the |
| 429 | compiler. They are useful for runtime instrumentation and static analysis. |
| 430 | |
| 431 | See Documentation/gcc-plugins.txt for details. |
| 432 | |
| 433 | config GCC_PLUGIN_CYC_COMPLEXITY |
| 434 | bool "Compute the cyclomatic complexity of a function" if EXPERT |
| 435 | depends on GCC_PLUGINS |
| 436 | depends on !COMPILE_TEST # too noisy |
| 437 | help |
| 438 | The complexity M of a function's control flow graph is defined as: |
| 439 | M = E - N + 2P |
| 440 | where |
| 441 | |
| 442 | E = the number of edges |
| 443 | N = the number of nodes |
| 444 | P = the number of connected components (exit nodes). |
| 445 | |
| 446 | Enabling this plugin reports the complexity to stderr during the |
| 447 | build. It mainly serves as a simple example of how to create a |
| 448 | gcc plugin for the kernel. |
| 449 | |
| 450 | config GCC_PLUGIN_SANCOV |
| 451 | bool |
| 452 | depends on GCC_PLUGINS |
| 453 | help |
| 454 | This plugin inserts a __sanitizer_cov_trace_pc() call at the start of |
| 455 | basic blocks. It supports all gcc versions with plugin support (from |
| 456 | gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" |
| 457 | by Dmitry Vyukov <dvyukov@google.com>. |
| 458 | |
| 459 | config GCC_PLUGIN_LATENT_ENTROPY |
| 460 | bool "Generate some entropy during boot and runtime" |
| 461 | depends on GCC_PLUGINS |
| 462 | help |
| 463 | By saying Y here the kernel will instrument some kernel code to |
| 464 | extract some entropy from both original and artificially created |
| 465 | program state. This will help especially embedded systems where |
| 466 | there is little 'natural' source of entropy normally. The cost |
| 467 | is some slowdown of the boot process (about 0.5%) and fork and |
| 468 | irq processing. |
| 469 | |
| 470 | Note that entropy extracted this way is not cryptographically |
| 471 | secure! |
| 472 | |
| 473 | This plugin was ported from grsecurity/PaX. More information at: |
| 474 | * https://grsecurity.net/ |
| 475 | * https://pax.grsecurity.net/ |
| 476 | |
| 477 | config GCC_PLUGIN_STRUCTLEAK |
| 478 | bool "Force initialization of variables containing userspace addresses" |
| 479 | depends on GCC_PLUGINS |
| 480 | # Currently STRUCTLEAK inserts initialization out of live scope of |
| 481 | # variables from KASAN point of view. This leads to KASAN false |
| 482 | # positive reports. Prohibit this combination for now. |
| 483 | depends on !KASAN_EXTRA |
| 484 | help |
| 485 | This plugin zero-initializes any structures containing a |
| 486 | __user attribute. This can prevent some classes of information |
| 487 | exposures. |
| 488 | |
| 489 | This plugin was ported from grsecurity/PaX. More information at: |
| 490 | * https://grsecurity.net/ |
| 491 | * https://pax.grsecurity.net/ |
| 492 | |
| 493 | config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL |
| 494 | bool "Force initialize all struct type variables passed by reference" |
| 495 | depends on GCC_PLUGIN_STRUCTLEAK |
| 496 | depends on !COMPILE_TEST |
| 497 | help |
| 498 | Zero initialize any struct type local variable that may be passed by |
| 499 | reference without having been initialized. |
| 500 | |
| 501 | config GCC_PLUGIN_STRUCTLEAK_VERBOSE |
| 502 | bool "Report forcefully initialized variables" |
| 503 | depends on GCC_PLUGIN_STRUCTLEAK |
| 504 | depends on !COMPILE_TEST # too noisy |
| 505 | help |
| 506 | This option will cause a warning to be printed each time the |
| 507 | structleak plugin finds a variable it thinks needs to be |
| 508 | initialized. Since not all existing initializers are detected |
| 509 | by the plugin, this can produce false positive warnings. |
| 510 | |
| 511 | config GCC_PLUGIN_RANDSTRUCT |
| 512 | bool "Randomize layout of sensitive kernel structures" |
| 513 | depends on GCC_PLUGINS |
| 514 | select MODVERSIONS if MODULES |
| 515 | help |
| 516 | If you say Y here, the layouts of structures that are entirely |
| 517 | function pointers (and have not been manually annotated with |
| 518 | __no_randomize_layout), or structures that have been explicitly |
| 519 | marked with __randomize_layout, will be randomized at compile-time. |
| 520 | This can introduce the requirement of an additional information |
| 521 | exposure vulnerability for exploits targeting these structure |
| 522 | types. |
| 523 | |
| 524 | Enabling this feature will introduce some performance impact, |
| 525 | slightly increase memory usage, and prevent the use of forensic |
| 526 | tools like Volatility against the system (unless the kernel |
| 527 | source tree isn't cleaned after kernel installation). |
| 528 | |
| 529 | The seed used for compilation is located at |
| 530 | scripts/gcc-plgins/randomize_layout_seed.h. It remains after |
| 531 | a make clean to allow for external modules to be compiled with |
| 532 | the existing seed and will be removed by a make mrproper or |
| 533 | make distclean. |
| 534 | |
| 535 | Note that the implementation requires gcc 4.7 or newer. |
| 536 | |
| 537 | This plugin was ported from grsecurity/PaX. More information at: |
| 538 | * https://grsecurity.net/ |
| 539 | * https://pax.grsecurity.net/ |
| 540 | |
| 541 | config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE |
| 542 | bool "Use cacheline-aware structure randomization" |
| 543 | depends on GCC_PLUGIN_RANDSTRUCT |
| 544 | depends on !COMPILE_TEST # do not reduce test coverage |
| 545 | help |
| 546 | If you say Y here, the RANDSTRUCT randomization will make a |
| 547 | best effort at restricting randomization to cacheline-sized |
| 548 | groups of elements. It will further not randomize bitfields |
| 549 | in structures. This reduces the performance hit of RANDSTRUCT |
| 550 | at the cost of weakened randomization. |
| 551 | |
| 552 | config HAVE_STACKPROTECTOR |
| 553 | bool |
| 554 | help |
| 555 | An arch should select this symbol if: |
| 556 | - it has implemented a stack canary (e.g. __stack_chk_guard) |
| 557 | |
| 558 | config CC_HAS_STACKPROTECTOR_NONE |
| 559 | def_bool $(cc-option,-fno-stack-protector) |
| 560 | |
| 561 | config STACKPROTECTOR |
| 562 | bool "Stack Protector buffer overflow detection" |
| 563 | depends on HAVE_STACKPROTECTOR |
| 564 | depends on $(cc-option,-fstack-protector) |
| 565 | default y |
| 566 | help |
| 567 | This option turns on the "stack-protector" GCC feature. This |
| 568 | feature puts, at the beginning of functions, a canary value on |
| 569 | the stack just before the return address, and validates |
| 570 | the value just before actually returning. Stack based buffer |
| 571 | overflows (that need to overwrite this return address) now also |
| 572 | overwrite the canary, which gets detected and the attack is then |
| 573 | neutralized via a kernel panic. |
| 574 | |
| 575 | Functions will have the stack-protector canary logic added if they |
| 576 | have an 8-byte or larger character array on the stack. |
| 577 | |
| 578 | This feature requires gcc version 4.2 or above, or a distribution |
| 579 | gcc with the feature backported ("-fstack-protector"). |
| 580 | |
| 581 | On an x86 "defconfig" build, this feature adds canary checks to |
| 582 | about 3% of all kernel functions, which increases kernel code size |
| 583 | by about 0.3%. |
| 584 | |
| 585 | config STACKPROTECTOR_STRONG |
| 586 | bool "Strong Stack Protector" |
| 587 | depends on STACKPROTECTOR |
| 588 | depends on $(cc-option,-fstack-protector-strong) |
| 589 | default y |
| 590 | help |
| 591 | Functions will have the stack-protector canary logic added in any |
| 592 | of the following conditions: |
| 593 | |
| 594 | - local variable's address used as part of the right hand side of an |
| 595 | assignment or function argument |
| 596 | - local variable is an array (or union containing an array), |
| 597 | regardless of array type or length |
| 598 | - uses register local variables |
| 599 | |
| 600 | This feature requires gcc version 4.9 or above, or a distribution |
| 601 | gcc with the feature backported ("-fstack-protector-strong"). |
| 602 | |
| 603 | On an x86 "defconfig" build, this feature adds canary checks to |
| 604 | about 20% of all kernel functions, which increases the kernel code |
| 605 | size by about 2%. |
| 606 | |
| 607 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
| 608 | bool |
| 609 | help |
| 610 | An architecture should select this if it can walk the kernel stack |
| 611 | frames to determine if an object is part of either the arguments |
| 612 | or local variables (i.e. that it excludes saved return addresses, |
| 613 | and similar) by implementing an inline arch_within_stack_frames(), |
| 614 | which is used by CONFIG_HARDENED_USERCOPY. |
| 615 | |
| 616 | config HAVE_CONTEXT_TRACKING |
| 617 | bool |
| 618 | help |
| 619 | Provide kernel/user boundaries probes necessary for subsystems |
| 620 | that need it, such as userspace RCU extended quiescent state. |
| 621 | Syscalls need to be wrapped inside user_exit()-user_enter() through |
| 622 | the slow path using TIF_NOHZ flag. Exceptions handlers must be |
| 623 | wrapped as well. Irqs are already protected inside |
| 624 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on |
| 625 | irq exit still need to be protected. |
| 626 | |
| 627 | config HAVE_VIRT_CPU_ACCOUNTING |
| 628 | bool |
| 629 | |
| 630 | config ARCH_HAS_SCALED_CPUTIME |
| 631 | bool |
| 632 | |
| 633 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
| 634 | bool |
| 635 | default y if 64BIT |
| 636 | help |
| 637 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. |
| 638 | Before enabling this option, arch code must be audited |
| 639 | to ensure there are no races in concurrent read/write of |
| 640 | cputime_t. For example, reading/writing 64-bit cputime_t on |
| 641 | some 32-bit arches may require multiple accesses, so proper |
| 642 | locking is needed to protect against concurrent accesses. |
| 643 | |
| 644 | |
| 645 | config HAVE_IRQ_TIME_ACCOUNTING |
| 646 | bool |
| 647 | help |
| 648 | Archs need to ensure they use a high enough resolution clock to |
| 649 | support irq time accounting and then call enable_sched_clock_irqtime(). |
| 650 | |
| 651 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
| 652 | bool |
| 653 | |
| 654 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
| 655 | bool |
| 656 | |
| 657 | config HAVE_ARCH_HUGE_VMAP |
| 658 | bool |
| 659 | |
| 660 | config HAVE_ARCH_SOFT_DIRTY |
| 661 | bool |
| 662 | |
| 663 | config HAVE_MOD_ARCH_SPECIFIC |
| 664 | bool |
| 665 | help |
| 666 | The arch uses struct mod_arch_specific to store data. Many arches |
| 667 | just need a simple module loader without arch specific data - those |
| 668 | should not enable this. |
| 669 | |
| 670 | config MODULES_USE_ELF_RELA |
| 671 | bool |
| 672 | help |
| 673 | Modules only use ELF RELA relocations. Modules with ELF REL |
| 674 | relocations will give an error. |
| 675 | |
| 676 | config MODULES_USE_ELF_REL |
| 677 | bool |
| 678 | help |
| 679 | Modules only use ELF REL relocations. Modules with ELF RELA |
| 680 | relocations will give an error. |
| 681 | |
| 682 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
| 683 | bool |
| 684 | help |
| 685 | Architecture doesn't only execute the irq handler on the irq stack |
| 686 | but also irq_exit(). This way we can process softirqs on this irq |
| 687 | stack instead of switching to a new one when we call __do_softirq() |
| 688 | in the end of an hardirq. |
| 689 | This spares a stack switch and improves cache usage on softirq |
| 690 | processing. |
| 691 | |
| 692 | config PGTABLE_LEVELS |
| 693 | int |
| 694 | default 2 |
| 695 | |
| 696 | config ARCH_HAS_ELF_RANDOMIZE |
| 697 | bool |
| 698 | help |
| 699 | An architecture supports choosing randomized locations for |
| 700 | stack, mmap, brk, and ET_DYN. Defined functions: |
| 701 | - arch_mmap_rnd() |
| 702 | - arch_randomize_brk() |
| 703 | |
| 704 | config HAVE_ARCH_MMAP_RND_BITS |
| 705 | bool |
| 706 | help |
| 707 | An arch should select this symbol if it supports setting a variable |
| 708 | number of bits for use in establishing the base address for mmap |
| 709 | allocations, has MMU enabled and provides values for both: |
| 710 | - ARCH_MMAP_RND_BITS_MIN |
| 711 | - ARCH_MMAP_RND_BITS_MAX |
| 712 | |
| 713 | config HAVE_EXIT_THREAD |
| 714 | bool |
| 715 | help |
| 716 | An architecture implements exit_thread. |
| 717 | |
| 718 | config ARCH_MMAP_RND_BITS_MIN |
| 719 | int |
| 720 | |
| 721 | config ARCH_MMAP_RND_BITS_MAX |
| 722 | int |
| 723 | |
| 724 | config ARCH_MMAP_RND_BITS_DEFAULT |
| 725 | int |
| 726 | |
| 727 | config ARCH_MMAP_RND_BITS |
| 728 | int "Number of bits to use for ASLR of mmap base address" if EXPERT |
| 729 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX |
| 730 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT |
| 731 | default ARCH_MMAP_RND_BITS_MIN |
| 732 | depends on HAVE_ARCH_MMAP_RND_BITS |
| 733 | help |
| 734 | This value can be used to select the number of bits to use to |
| 735 | determine the random offset to the base address of vma regions |
| 736 | resulting from mmap allocations. This value will be bounded |
| 737 | by the architecture's minimum and maximum supported values. |
| 738 | |
| 739 | This value can be changed after boot using the |
| 740 | /proc/sys/vm/mmap_rnd_bits tunable |
| 741 | |
| 742 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 743 | bool |
| 744 | help |
| 745 | An arch should select this symbol if it supports running applications |
| 746 | in compatibility mode, supports setting a variable number of bits for |
| 747 | use in establishing the base address for mmap allocations, has MMU |
| 748 | enabled and provides values for both: |
| 749 | - ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 750 | - ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 751 | |
| 752 | config ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 753 | int |
| 754 | |
| 755 | config ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 756 | int |
| 757 | |
| 758 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| 759 | int |
| 760 | |
| 761 | config ARCH_MMAP_RND_COMPAT_BITS |
| 762 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT |
| 763 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 764 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| 765 | default ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 766 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 767 | help |
| 768 | This value can be used to select the number of bits to use to |
| 769 | determine the random offset to the base address of vma regions |
| 770 | resulting from mmap allocations for compatible applications This |
| 771 | value will be bounded by the architecture's minimum and maximum |
| 772 | supported values. |
| 773 | |
| 774 | This value can be changed after boot using the |
| 775 | /proc/sys/vm/mmap_rnd_compat_bits tunable |
| 776 | |
| 777 | config HAVE_ARCH_COMPAT_MMAP_BASES |
| 778 | bool |
| 779 | help |
| 780 | This allows 64bit applications to invoke 32-bit mmap() syscall |
| 781 | and vice-versa 32-bit applications to call 64-bit mmap(). |
| 782 | Required for applications doing different bitness syscalls. |
| 783 | |
| 784 | config HAVE_COPY_THREAD_TLS |
| 785 | bool |
| 786 | help |
| 787 | Architecture provides copy_thread_tls to accept tls argument via |
| 788 | normal C parameter passing, rather than extracting the syscall |
| 789 | argument from pt_regs. |
| 790 | |
| 791 | config HAVE_STACK_VALIDATION |
| 792 | bool |
| 793 | help |
| 794 | Architecture supports the 'objtool check' host tool command, which |
| 795 | performs compile-time stack metadata validation. |
| 796 | |
| 797 | config HAVE_RELIABLE_STACKTRACE |
| 798 | bool |
| 799 | help |
| 800 | Architecture has a save_stack_trace_tsk_reliable() function which |
| 801 | only returns a stack trace if it can guarantee the trace is reliable. |
| 802 | |
| 803 | config HAVE_ARCH_HASH |
| 804 | bool |
| 805 | default n |
| 806 | help |
| 807 | If this is set, the architecture provides an <asm/hash.h> |
| 808 | file which provides platform-specific implementations of some |
| 809 | functions in <linux/hash.h> or fs/namei.c. |
| 810 | |
| 811 | config ISA_BUS_API |
| 812 | def_bool ISA |
| 813 | |
| 814 | # |
| 815 | # ABI hall of shame |
| 816 | # |
| 817 | config CLONE_BACKWARDS |
| 818 | bool |
| 819 | help |
| 820 | Architecture has tls passed as the 4th argument of clone(2), |
| 821 | not the 5th one. |
| 822 | |
| 823 | config CLONE_BACKWARDS2 |
| 824 | bool |
| 825 | help |
| 826 | Architecture has the first two arguments of clone(2) swapped. |
| 827 | |
| 828 | config CLONE_BACKWARDS3 |
| 829 | bool |
| 830 | help |
| 831 | Architecture has tls passed as the 3rd argument of clone(2), |
| 832 | not the 5th one. |
| 833 | |
| 834 | config ODD_RT_SIGACTION |
| 835 | bool |
| 836 | help |
| 837 | Architecture has unusual rt_sigaction(2) arguments |
| 838 | |
| 839 | config OLD_SIGSUSPEND |
| 840 | bool |
| 841 | help |
| 842 | Architecture has old sigsuspend(2) syscall, of one-argument variety |
| 843 | |
| 844 | config OLD_SIGSUSPEND3 |
| 845 | bool |
| 846 | help |
| 847 | Even weirder antique ABI - three-argument sigsuspend(2) |
| 848 | |
| 849 | config OLD_SIGACTION |
| 850 | bool |
| 851 | help |
| 852 | Architecture has old sigaction(2) syscall. Nope, not the same |
| 853 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), |
| 854 | but fairly different variant of sigaction(2), thanks to OSF/1 |
| 855 | compatibility... |
| 856 | |
| 857 | config COMPAT_OLD_SIGACTION |
| 858 | bool |
| 859 | |
| 860 | config 64BIT_TIME |
| 861 | def_bool ARCH_HAS_64BIT_TIME |
| 862 | help |
| 863 | This should be selected by all architectures that need to support |
| 864 | new system calls with a 64-bit time_t. This is relevant on all 32-bit |
| 865 | architectures, and 64-bit architectures as part of compat syscall |
| 866 | handling. |
| 867 | |
| 868 | config COMPAT_32BIT_TIME |
| 869 | def_bool (!64BIT && 64BIT_TIME) || COMPAT |
| 870 | help |
| 871 | This enables 32 bit time_t support in addition to 64 bit time_t support. |
| 872 | This is relevant on all 32-bit architectures, and 64-bit architectures |
| 873 | as part of compat syscall handling. |
| 874 | |
| 875 | config ARCH_NO_COHERENT_DMA_MMAP |
| 876 | bool |
| 877 | |
| 878 | config CPU_NO_EFFICIENT_FFS |
| 879 | def_bool n |
| 880 | |
| 881 | config HAVE_ARCH_VMAP_STACK |
| 882 | def_bool n |
| 883 | help |
| 884 | An arch should select this symbol if it can support kernel stacks |
| 885 | in vmalloc space. This means: |
| 886 | |
| 887 | - vmalloc space must be large enough to hold many kernel stacks. |
| 888 | This may rule out many 32-bit architectures. |
| 889 | |
| 890 | - Stacks in vmalloc space need to work reliably. For example, if |
| 891 | vmap page tables are created on demand, either this mechanism |
| 892 | needs to work while the stack points to a virtual address with |
| 893 | unpopulated page tables or arch code (switch_to() and switch_mm(), |
| 894 | most likely) needs to ensure that the stack's page table entries |
| 895 | are populated before running on a possibly unpopulated stack. |
| 896 | |
| 897 | - If the stack overflows into a guard page, something reasonable |
| 898 | should happen. The definition of "reasonable" is flexible, but |
| 899 | instantly rebooting without logging anything would be unfriendly. |
| 900 | |
| 901 | config VMAP_STACK |
| 902 | default y |
| 903 | bool "Use a virtually-mapped stack" |
| 904 | depends on HAVE_ARCH_VMAP_STACK && !KASAN |
| 905 | ---help--- |
| 906 | Enable this if you want the use virtually-mapped kernel stacks |
| 907 | with guard pages. This causes kernel stack overflows to be |
| 908 | caught immediately rather than causing difficult-to-diagnose |
| 909 | corruption. |
| 910 | |
| 911 | This is presently incompatible with KASAN because KASAN expects |
| 912 | the stack to map directly to the KASAN shadow map using a formula |
| 913 | that is incorrect if the stack is in vmalloc space. |
| 914 | |
| 915 | config ARCH_OPTIONAL_KERNEL_RWX |
| 916 | def_bool n |
| 917 | |
| 918 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 919 | def_bool n |
| 920 | |
| 921 | config ARCH_HAS_STRICT_KERNEL_RWX |
| 922 | def_bool n |
| 923 | |
| 924 | config STRICT_KERNEL_RWX |
| 925 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
| 926 | depends on ARCH_HAS_STRICT_KERNEL_RWX |
| 927 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 928 | help |
| 929 | If this is set, kernel text and rodata memory will be made read-only, |
| 930 | and non-text memory will be made non-executable. This provides |
| 931 | protection against certain security exploits (e.g. executing the heap |
| 932 | or modifying text) |
| 933 | |
| 934 | These features are considered standard security practice these days. |
| 935 | You should say Y here in almost all cases. |
| 936 | |
| 937 | config ARCH_HAS_STRICT_MODULE_RWX |
| 938 | def_bool n |
| 939 | |
| 940 | config STRICT_MODULE_RWX |
| 941 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
| 942 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES |
| 943 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 944 | help |
| 945 | If this is set, module text and rodata memory will be made read-only, |
| 946 | and non-text memory will be made non-executable. This provides |
| 947 | protection against certain security exploits (e.g. writing to text) |
| 948 | |
| 949 | # select if the architecture provides an asm/dma-direct.h header |
| 950 | config ARCH_HAS_PHYS_TO_DMA |
| 951 | bool |
| 952 | |
| 953 | config ARCH_HAS_REFCOUNT |
| 954 | bool |
| 955 | help |
| 956 | An architecture selects this when it has implemented refcount_t |
| 957 | using open coded assembly primitives that provide an optimized |
| 958 | refcount_t implementation, possibly at the expense of some full |
| 959 | refcount state checks of CONFIG_REFCOUNT_FULL=y. |
| 960 | |
| 961 | The refcount overflow check behavior, however, must be retained. |
| 962 | Catching overflows is the primary security concern for protecting |
| 963 | against bugs in reference counts. |
| 964 | |
| 965 | config REFCOUNT_FULL |
| 966 | bool "Perform full reference count validation at the expense of speed" |
| 967 | help |
| 968 | Enabling this switches the refcounting infrastructure from a fast |
| 969 | unchecked atomic_t implementation to a fully state checked |
| 970 | implementation, which can be (slightly) slower but provides protections |
| 971 | against various use-after-free conditions that can be used in |
| 972 | security flaw exploits. |
| 973 | |
| 974 | source "kernel/gcov/Kconfig" |