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