linux/include/linux/kernel.h
<<
>>
Prefs
   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_KERNEL_H
   3#define _LINUX_KERNEL_H
   4
   5#include <linux/stdarg.h>
   6#include <linux/align.h>
   7#include <linux/limits.h>
   8#include <linux/linkage.h>
   9#include <linux/stddef.h>
  10#include <linux/types.h>
  11#include <linux/compiler.h>
  12#include <linux/bitops.h>
  13#include <linux/kstrtox.h>
  14#include <linux/log2.h>
  15#include <linux/math.h>
  16#include <linux/minmax.h>
  17#include <linux/typecheck.h>
  18#include <linux/panic.h>
  19#include <linux/printk.h>
  20#include <linux/build_bug.h>
  21#include <linux/static_call_types.h>
  22#include <asm/byteorder.h>
  23
  24#include <uapi/linux/kernel.h>
  25
  26#define STACK_MAGIC     0xdeadbeef
  27
  28/**
  29 * REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value
  30 * @x: value to repeat
  31 *
  32 * NOTE: @x is not checked for > 0xff; larger values produce odd results.
  33 */
  34#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
  35
  36/* generic data direction definitions */
  37#define READ                    0
  38#define WRITE                   1
  39
  40/**
  41 * ARRAY_SIZE - get the number of elements in array @arr
  42 * @arr: array to be sized
  43 */
  44#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  45
  46#define PTR_IF(cond, ptr)       ((cond) ? (ptr) : NULL)
  47
  48#define u64_to_user_ptr(x) (            \
  49{                                       \
  50        typecheck(u64, (x));            \
  51        (void __user *)(uintptr_t)(x);  \
  52}                                       \
  53)
  54
  55#define typeof_member(T, m)     typeof(((T*)0)->m)
  56
  57#define _RET_IP_                (unsigned long)__builtin_return_address(0)
  58#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
  59
  60/**
  61 * upper_32_bits - return bits 32-63 of a number
  62 * @n: the number we're accessing
  63 *
  64 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
  65 * the "right shift count >= width of type" warning when that quantity is
  66 * 32-bits.
  67 */
  68#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
  69
  70/**
  71 * lower_32_bits - return bits 0-31 of a number
  72 * @n: the number we're accessing
  73 */
  74#define lower_32_bits(n) ((u32)((n) & 0xffffffff))
  75
  76/**
  77 * upper_16_bits - return bits 16-31 of a number
  78 * @n: the number we're accessing
  79 */
  80#define upper_16_bits(n) ((u16)((n) >> 16))
  81
  82/**
  83 * lower_16_bits - return bits 0-15 of a number
  84 * @n: the number we're accessing
  85 */
  86#define lower_16_bits(n) ((u16)((n) & 0xffff))
  87
  88struct completion;
  89struct user;
  90
  91#ifdef CONFIG_PREEMPT_VOLUNTARY
  92
  93extern int __cond_resched(void);
  94# define might_resched() __cond_resched()
  95
  96#elif defined(CONFIG_PREEMPT_DYNAMIC)
  97
  98extern int __cond_resched(void);
  99
 100DECLARE_STATIC_CALL(might_resched, __cond_resched);
 101
 102static __always_inline void might_resched(void)
 103{
 104        static_call_mod(might_resched)();
 105}
 106
 107#else
 108
 109# define might_resched() do { } while (0)
 110
 111#endif /* CONFIG_PREEMPT_* */
 112
 113#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 114extern void ___might_sleep(const char *file, int line, int preempt_offset);
 115extern void __might_sleep(const char *file, int line, int preempt_offset);
 116extern void __cant_sleep(const char *file, int line, int preempt_offset);
 117extern void __cant_migrate(const char *file, int line);
 118
 119/**
 120 * might_sleep - annotation for functions that can sleep
 121 *
 122 * this macro will print a stack trace if it is executed in an atomic
 123 * context (spinlock, irq-handler, ...). Additional sections where blocking is
 124 * not allowed can be annotated with non_block_start() and non_block_end()
 125 * pairs.
 126 *
 127 * This is a useful debugging help to be able to catch problems early and not
 128 * be bitten later when the calling function happens to sleep when it is not
 129 * supposed to.
 130 */
 131# define might_sleep() \
 132        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 133/**
 134 * cant_sleep - annotation for functions that cannot sleep
 135 *
 136 * this macro will print a stack trace if it is executed with preemption enabled
 137 */
 138# define cant_sleep() \
 139        do { __cant_sleep(__FILE__, __LINE__, 0); } while (0)
 140# define sched_annotate_sleep() (current->task_state_change = 0)
 141
 142/**
 143 * cant_migrate - annotation for functions that cannot migrate
 144 *
 145 * Will print a stack trace if executed in code which is migratable
 146 */
 147# define cant_migrate()                                                 \
 148        do {                                                            \
 149                if (IS_ENABLED(CONFIG_SMP))                             \
 150                        __cant_migrate(__FILE__, __LINE__);             \
 151        } while (0)
 152
 153/**
 154 * non_block_start - annotate the start of section where sleeping is prohibited
 155 *
 156 * This is on behalf of the oom reaper, specifically when it is calling the mmu
 157 * notifiers. The problem is that if the notifier were to block on, for example,
 158 * mutex_lock() and if the process which holds that mutex were to perform a
 159 * sleeping memory allocation, the oom reaper is now blocked on completion of
 160 * that memory allocation. Other blocking calls like wait_event() pose similar
 161 * issues.
 162 */
 163# define non_block_start() (current->non_block_count++)
 164/**
 165 * non_block_end - annotate the end of section where sleeping is prohibited
 166 *
 167 * Closes a section opened by non_block_start().
 168 */
 169# define non_block_end() WARN_ON(current->non_block_count-- == 0)
 170#else
 171  static inline void ___might_sleep(const char *file, int line,
 172                                   int preempt_offset) { }
 173  static inline void __might_sleep(const char *file, int line,
 174                                   int preempt_offset) { }
 175# define might_sleep() do { might_resched(); } while (0)
 176# define cant_sleep() do { } while (0)
 177# define cant_migrate()         do { } while (0)
 178# define sched_annotate_sleep() do { } while (0)
 179# define non_block_start() do { } while (0)
 180# define non_block_end() do { } while (0)
 181#endif
 182
 183#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 184
 185#if defined(CONFIG_MMU) && \
 186        (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
 187#define might_fault() __might_fault(__FILE__, __LINE__)
 188void __might_fault(const char *file, int line);
 189#else
 190static inline void might_fault(void) { }
 191#endif
 192
 193void do_exit(long error_code) __noreturn;
 194void complete_and_exit(struct completion *, long) __noreturn;
 195
 196extern int num_to_str(char *buf, int size,
 197                      unsigned long long num, unsigned int width);
 198
 199/* lib/printf utilities */
 200
 201extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 202extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 203extern __printf(3, 4)
 204int snprintf(char *buf, size_t size, const char *fmt, ...);
 205extern __printf(3, 0)
 206int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 207extern __printf(3, 4)
 208int scnprintf(char *buf, size_t size, const char *fmt, ...);
 209extern __printf(3, 0)
 210int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 211extern __printf(2, 3) __malloc
 212char *kasprintf(gfp_t gfp, const char *fmt, ...);
 213extern __printf(2, 0) __malloc
 214char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 215extern __printf(2, 0)
 216const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);
 217
 218extern __scanf(2, 3)
 219int sscanf(const char *, const char *, ...);
 220extern __scanf(2, 0)
 221int vsscanf(const char *, const char *, va_list);
 222
 223extern int no_hash_pointers_enable(char *str);
 224
 225extern int get_option(char **str, int *pint);
 226extern char *get_options(const char *str, int nints, int *ints);
 227extern unsigned long long memparse(const char *ptr, char **retptr);
 228extern bool parse_option_str(const char *str, const char *option);
 229extern char *next_arg(char *args, char **param, char **val);
 230
 231extern int core_kernel_text(unsigned long addr);
 232extern int init_kernel_text(unsigned long addr);
 233extern int core_kernel_data(unsigned long addr);
 234extern int __kernel_text_address(unsigned long addr);
 235extern int kernel_text_address(unsigned long addr);
 236extern int func_ptr_is_kernel_text(void *ptr);
 237
 238extern void bust_spinlocks(int yes);
 239
 240extern int root_mountflags;
 241
 242extern bool early_boot_irqs_disabled;
 243
 244/*
 245 * Values used for system_state. Ordering of the states must not be changed
 246 * as code checks for <, <=, >, >= STATE.
 247 */
 248extern enum system_states {
 249        SYSTEM_BOOTING,
 250        SYSTEM_SCHEDULING,
 251        SYSTEM_RUNNING,
 252        SYSTEM_HALT,
 253        SYSTEM_POWER_OFF,
 254        SYSTEM_RESTART,
 255        SYSTEM_SUSPEND,
 256} system_state;
 257
 258extern const char hex_asc[];
 259#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 260#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 261
 262static inline char *hex_byte_pack(char *buf, u8 byte)
 263{
 264        *buf++ = hex_asc_hi(byte);
 265        *buf++ = hex_asc_lo(byte);
 266        return buf;
 267}
 268
 269extern const char hex_asc_upper[];
 270#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 271#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 272
 273static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 274{
 275        *buf++ = hex_asc_upper_hi(byte);
 276        *buf++ = hex_asc_upper_lo(byte);
 277        return buf;
 278}
 279
 280extern int hex_to_bin(char ch);
 281extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 282extern char *bin2hex(char *dst, const void *src, size_t count);
 283
 284bool mac_pton(const char *s, u8 *mac);
 285
 286/*
 287 * General tracing related utility functions - trace_printk(),
 288 * tracing_on/tracing_off and tracing_start()/tracing_stop
 289 *
 290 * Use tracing_on/tracing_off when you want to quickly turn on or off
 291 * tracing. It simply enables or disables the recording of the trace events.
 292 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 293 * file, which gives a means for the kernel and userspace to interact.
 294 * Place a tracing_off() in the kernel where you want tracing to end.
 295 * From user space, examine the trace, and then echo 1 > tracing_on
 296 * to continue tracing.
 297 *
 298 * tracing_stop/tracing_start has slightly more overhead. It is used
 299 * by things like suspend to ram where disabling the recording of the
 300 * trace is not enough, but tracing must actually stop because things
 301 * like calling smp_processor_id() may crash the system.
 302 *
 303 * Most likely, you want to use tracing_on/tracing_off.
 304 */
 305
 306enum ftrace_dump_mode {
 307        DUMP_NONE,
 308        DUMP_ALL,
 309        DUMP_ORIG,
 310};
 311
 312#ifdef CONFIG_TRACING
 313void tracing_on(void);
 314void tracing_off(void);
 315int tracing_is_on(void);
 316void tracing_snapshot(void);
 317void tracing_snapshot_alloc(void);
 318
 319extern void tracing_start(void);
 320extern void tracing_stop(void);
 321
 322static inline __printf(1, 2)
 323void ____trace_printk_check_format(const char *fmt, ...)
 324{
 325}
 326#define __trace_printk_check_format(fmt, args...)                       \
 327do {                                                                    \
 328        if (0)                                                          \
 329                ____trace_printk_check_format(fmt, ##args);             \
 330} while (0)
 331
 332/**
 333 * trace_printk - printf formatting in the ftrace buffer
 334 * @fmt: the printf format for printing
 335 *
 336 * Note: __trace_printk is an internal function for trace_printk() and
 337 *       the @ip is passed in via the trace_printk() macro.
 338 *
 339 * This function allows a kernel developer to debug fast path sections
 340 * that printk is not appropriate for. By scattering in various
 341 * printk like tracing in the code, a developer can quickly see
 342 * where problems are occurring.
 343 *
 344 * This is intended as a debugging tool for the developer only.
 345 * Please refrain from leaving trace_printks scattered around in
 346 * your code. (Extra memory is used for special buffers that are
 347 * allocated when trace_printk() is used.)
 348 *
 349 * A little optimization trick is done here. If there's only one
 350 * argument, there's no need to scan the string for printf formats.
 351 * The trace_puts() will suffice. But how can we take advantage of
 352 * using trace_puts() when trace_printk() has only one argument?
 353 * By stringifying the args and checking the size we can tell
 354 * whether or not there are args. __stringify((__VA_ARGS__)) will
 355 * turn into "()\0" with a size of 3 when there are no args, anything
 356 * else will be bigger. All we need to do is define a string to this,
 357 * and then take its size and compare to 3. If it's bigger, use
 358 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 359 * let gcc optimize the rest.
 360 */
 361
 362#define trace_printk(fmt, ...)                          \
 363do {                                                    \
 364        char _______STR[] = __stringify((__VA_ARGS__)); \
 365        if (sizeof(_______STR) > 3)                     \
 366                do_trace_printk(fmt, ##__VA_ARGS__);    \
 367        else                                            \
 368                trace_puts(fmt);                        \
 369} while (0)
 370
 371#define do_trace_printk(fmt, args...)                                   \
 372do {                                                                    \
 373        static const char *trace_printk_fmt __used                      \
 374                __section("__trace_printk_fmt") =                       \
 375                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 376                                                                        \
 377        __trace_printk_check_format(fmt, ##args);                       \
 378                                                                        \
 379        if (__builtin_constant_p(fmt))                                  \
 380                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 381        else                                                            \
 382                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 383} while (0)
 384
 385extern __printf(2, 3)
 386int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 387
 388extern __printf(2, 3)
 389int __trace_printk(unsigned long ip, const char *fmt, ...);
 390
 391/**
 392 * trace_puts - write a string into the ftrace buffer
 393 * @str: the string to record
 394 *
 395 * Note: __trace_bputs is an internal function for trace_puts and
 396 *       the @ip is passed in via the trace_puts macro.
 397 *
 398 * This is similar to trace_printk() but is made for those really fast
 399 * paths that a developer wants the least amount of "Heisenbug" effects,
 400 * where the processing of the print format is still too much.
 401 *
 402 * This function allows a kernel developer to debug fast path sections
 403 * that printk is not appropriate for. By scattering in various
 404 * printk like tracing in the code, a developer can quickly see
 405 * where problems are occurring.
 406 *
 407 * This is intended as a debugging tool for the developer only.
 408 * Please refrain from leaving trace_puts scattered around in
 409 * your code. (Extra memory is used for special buffers that are
 410 * allocated when trace_puts() is used.)
 411 *
 412 * Returns: 0 if nothing was written, positive # if string was.
 413 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 414 */
 415
 416#define trace_puts(str) ({                                              \
 417        static const char *trace_printk_fmt __used                      \
 418                __section("__trace_printk_fmt") =                       \
 419                __builtin_constant_p(str) ? str : NULL;                 \
 420                                                                        \
 421        if (__builtin_constant_p(str))                                  \
 422                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 423        else                                                            \
 424                __trace_puts(_THIS_IP_, str, strlen(str));              \
 425})
 426extern int __trace_bputs(unsigned long ip, const char *str);
 427extern int __trace_puts(unsigned long ip, const char *str, int size);
 428
 429extern void trace_dump_stack(int skip);
 430
 431/*
 432 * The double __builtin_constant_p is because gcc will give us an error
 433 * if we try to allocate the static variable to fmt if it is not a
 434 * constant. Even with the outer if statement.
 435 */
 436#define ftrace_vprintk(fmt, vargs)                                      \
 437do {                                                                    \
 438        if (__builtin_constant_p(fmt)) {                                \
 439                static const char *trace_printk_fmt __used              \
 440                  __section("__trace_printk_fmt") =                     \
 441                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 442                                                                        \
 443                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 444        } else                                                          \
 445                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 446} while (0)
 447
 448extern __printf(2, 0) int
 449__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 450
 451extern __printf(2, 0) int
 452__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 453
 454extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 455#else
 456static inline void tracing_start(void) { }
 457static inline void tracing_stop(void) { }
 458static inline void trace_dump_stack(int skip) { }
 459
 460static inline void tracing_on(void) { }
 461static inline void tracing_off(void) { }
 462static inline int tracing_is_on(void) { return 0; }
 463static inline void tracing_snapshot(void) { }
 464static inline void tracing_snapshot_alloc(void) { }
 465
 466static inline __printf(1, 2)
 467int trace_printk(const char *fmt, ...)
 468{
 469        return 0;
 470}
 471static __printf(1, 0) inline int
 472ftrace_vprintk(const char *fmt, va_list ap)
 473{
 474        return 0;
 475}
 476static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 477#endif /* CONFIG_TRACING */
 478
 479/* This counts to 12. Any more, it will return 13th argument. */
 480#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n
 481#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
 482
 483#define __CONCAT(a, b) a ## b
 484#define CONCATENATE(a, b) __CONCAT(a, b)
 485
 486/**
 487 * container_of - cast a member of a structure out to the containing structure
 488 * @ptr:        the pointer to the member.
 489 * @type:       the type of the container struct this is embedded in.
 490 * @member:     the name of the member within the struct.
 491 *
 492 */
 493#define container_of(ptr, type, member) ({                              \
 494        void *__mptr = (void *)(ptr);                                   \
 495        BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) &&   \
 496                         !__same_type(*(ptr), void),                    \
 497                         "pointer type mismatch in container_of()");    \
 498        ((type *)(__mptr - offsetof(type, member))); })
 499
 500/**
 501 * container_of_safe - cast a member of a structure out to the containing structure
 502 * @ptr:        the pointer to the member.
 503 * @type:       the type of the container struct this is embedded in.
 504 * @member:     the name of the member within the struct.
 505 *
 506 * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
 507 */
 508#define container_of_safe(ptr, type, member) ({                         \
 509        void *__mptr = (void *)(ptr);                                   \
 510        BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) &&   \
 511                         !__same_type(*(ptr), void),                    \
 512                         "pointer type mismatch in container_of()");    \
 513        IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) :                     \
 514                ((type *)(__mptr - offsetof(type, member))); })
 515
 516/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 517#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 518# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 519#endif
 520
 521/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
 522#define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
 523        (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
 524         BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
 525         /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
 526         BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
 527         BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
 528         /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
 529         BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
 530         /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
 531         BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
 532         (perms))
 533#endif
 534