linux/include/linux/kernel.h
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   1#ifndef _LINUX_KERNEL_H
   2#define _LINUX_KERNEL_H
   3
   4
   5#include <stdarg.h>
   6#include <linux/linkage.h>
   7#include <linux/stddef.h>
   8#include <linux/types.h>
   9#include <linux/compiler.h>
  10#include <linux/bitops.h>
  11#include <linux/log2.h>
  12#include <linux/typecheck.h>
  13#include <linux/printk.h>
  14#include <asm/byteorder.h>
  15#include <uapi/linux/kernel.h>
  16
  17#define USHRT_MAX       ((u16)(~0U))
  18#define SHRT_MAX        ((s16)(USHRT_MAX>>1))
  19#define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
  20#define INT_MAX         ((int)(~0U>>1))
  21#define INT_MIN         (-INT_MAX - 1)
  22#define UINT_MAX        (~0U)
  23#define LONG_MAX        ((long)(~0UL>>1))
  24#define LONG_MIN        (-LONG_MAX - 1)
  25#define ULONG_MAX       (~0UL)
  26#define LLONG_MAX       ((long long)(~0ULL>>1))
  27#define LLONG_MIN       (-LLONG_MAX - 1)
  28#define ULLONG_MAX      (~0ULL)
  29#define SIZE_MAX        (~(size_t)0)
  30
  31#define U8_MAX          ((u8)~0U)
  32#define S8_MAX          ((s8)(U8_MAX>>1))
  33#define S8_MIN          ((s8)(-S8_MAX - 1))
  34#define U16_MAX         ((u16)~0U)
  35#define S16_MAX         ((s16)(U16_MAX>>1))
  36#define S16_MIN         ((s16)(-S16_MAX - 1))
  37#define U32_MAX         ((u32)~0U)
  38#define S32_MAX         ((s32)(U32_MAX>>1))
  39#define S32_MIN         ((s32)(-S32_MAX - 1))
  40#define U64_MAX         ((u64)~0ULL)
  41#define S64_MAX         ((s64)(U64_MAX>>1))
  42#define S64_MIN         ((s64)(-S64_MAX - 1))
  43
  44#define STACK_MAGIC     0xdeadbeef
  45
  46#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
  47
  48#define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
  49#define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
  50#define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  51#define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  52
  53#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  54
  55#define u64_to_user_ptr(x) (            \
  56{                                       \
  57        typecheck(u64, x);              \
  58        (void __user *)(uintptr_t)x;    \
  59}                                       \
  60)
  61
  62/*
  63 * This looks more complex than it should be. But we need to
  64 * get the type for the ~ right in round_down (it needs to be
  65 * as wide as the result!), and we want to evaluate the macro
  66 * arguments just once each.
  67 */
  68#define __round_mask(x, y) ((__typeof__(x))((y)-1))
  69#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
  70#define round_down(x, y) ((x) & ~__round_mask(x, y))
  71
  72#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  73#define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
  74#define DIV_ROUND_UP_ULL(ll,d) \
  75        ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
  76
  77#if BITS_PER_LONG == 32
  78# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
  79#else
  80# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
  81#endif
  82
  83/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
  84#define roundup(x, y) (                                 \
  85{                                                       \
  86        const typeof(y) __y = y;                        \
  87        (((x) + (__y - 1)) / __y) * __y;                \
  88}                                                       \
  89)
  90#define rounddown(x, y) (                               \
  91{                                                       \
  92        typeof(x) __x = (x);                            \
  93        __x - (__x % (y));                              \
  94}                                                       \
  95)
  96
  97/*
  98 * Divide positive or negative dividend by positive divisor and round
  99 * to closest integer. Result is undefined for negative divisors and
 100 * for negative dividends if the divisor variable type is unsigned.
 101 */
 102#define DIV_ROUND_CLOSEST(x, divisor)(                  \
 103{                                                       \
 104        typeof(x) __x = x;                              \
 105        typeof(divisor) __d = divisor;                  \
 106        (((typeof(x))-1) > 0 ||                         \
 107         ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
 108                (((__x) + ((__d) / 2)) / (__d)) :       \
 109                (((__x) - ((__d) / 2)) / (__d));        \
 110}                                                       \
 111)
 112/*
 113 * Same as above but for u64 dividends. divisor must be a 32-bit
 114 * number.
 115 */
 116#define DIV_ROUND_CLOSEST_ULL(x, divisor)(              \
 117{                                                       \
 118        typeof(divisor) __d = divisor;                  \
 119        unsigned long long _tmp = (x) + (__d) / 2;      \
 120        do_div(_tmp, __d);                              \
 121        _tmp;                                           \
 122}                                                       \
 123)
 124
 125/*
 126 * Multiplies an integer by a fraction, while avoiding unnecessary
 127 * overflow or loss of precision.
 128 */
 129#define mult_frac(x, numer, denom)(                     \
 130{                                                       \
 131        typeof(x) quot = (x) / (denom);                 \
 132        typeof(x) rem  = (x) % (denom);                 \
 133        (quot * (numer)) + ((rem * (numer)) / (denom)); \
 134}                                                       \
 135)
 136
 137
 138#define _RET_IP_                (unsigned long)__builtin_return_address(0)
 139#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 140
 141#ifdef CONFIG_LBDAF
 142# include <asm/div64.h>
 143# define sector_div(a, b) do_div(a, b)
 144#else
 145# define sector_div(n, b)( \
 146{ \
 147        int _res; \
 148        _res = (n) % (b); \
 149        (n) /= (b); \
 150        _res; \
 151} \
 152)
 153#endif
 154
 155/**
 156 * upper_32_bits - return bits 32-63 of a number
 157 * @n: the number we're accessing
 158 *
 159 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 160 * the "right shift count >= width of type" warning when that quantity is
 161 * 32-bits.
 162 */
 163#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 164
 165/**
 166 * lower_32_bits - return bits 0-31 of a number
 167 * @n: the number we're accessing
 168 */
 169#define lower_32_bits(n) ((u32)(n))
 170
 171struct completion;
 172struct pt_regs;
 173struct user;
 174
 175#ifdef CONFIG_PREEMPT_VOLUNTARY
 176extern int _cond_resched(void);
 177# define might_resched() _cond_resched()
 178#else
 179# define might_resched() do { } while (0)
 180#endif
 181
 182#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 183  void ___might_sleep(const char *file, int line, int preempt_offset);
 184  void __might_sleep(const char *file, int line, int preempt_offset);
 185/**
 186 * might_sleep - annotation for functions that can sleep
 187 *
 188 * this macro will print a stack trace if it is executed in an atomic
 189 * context (spinlock, irq-handler, ...).
 190 *
 191 * This is a useful debugging help to be able to catch problems early and not
 192 * be bitten later when the calling function happens to sleep when it is not
 193 * supposed to.
 194 */
 195# define might_sleep() \
 196        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 197# define sched_annotate_sleep() (current->task_state_change = 0)
 198#else
 199  static inline void ___might_sleep(const char *file, int line,
 200                                   int preempt_offset) { }
 201  static inline void __might_sleep(const char *file, int line,
 202                                   int preempt_offset) { }
 203# define might_sleep() do { might_resched(); } while (0)
 204# define sched_annotate_sleep() do { } while (0)
 205#endif
 206
 207#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 208
 209/**
 210 * abs - return absolute value of an argument
 211 * @x: the value.  If it is unsigned type, it is converted to signed type first.
 212 *     char is treated as if it was signed (regardless of whether it really is)
 213 *     but the macro's return type is preserved as char.
 214 *
 215 * Return: an absolute value of x.
 216 */
 217#define abs(x)  __abs_choose_expr(x, long long,                         \
 218                __abs_choose_expr(x, long,                              \
 219                __abs_choose_expr(x, int,                               \
 220                __abs_choose_expr(x, short,                             \
 221                __abs_choose_expr(x, char,                              \
 222                __builtin_choose_expr(                                  \
 223                        __builtin_types_compatible_p(typeof(x), char),  \
 224                        (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
 225                        ((void)0)))))))
 226
 227#define __abs_choose_expr(x, type, other) __builtin_choose_expr(        \
 228        __builtin_types_compatible_p(typeof(x),   signed type) ||       \
 229        __builtin_types_compatible_p(typeof(x), unsigned type),         \
 230        ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
 231
 232/**
 233 * reciprocal_scale - "scale" a value into range [0, ep_ro)
 234 * @val: value
 235 * @ep_ro: right open interval endpoint
 236 *
 237 * Perform a "reciprocal multiplication" in order to "scale" a value into
 238 * range [0, ep_ro), where the upper interval endpoint is right-open.
 239 * This is useful, e.g. for accessing a index of an array containing
 240 * ep_ro elements, for example. Think of it as sort of modulus, only that
 241 * the result isn't that of modulo. ;) Note that if initial input is a
 242 * small value, then result will return 0.
 243 *
 244 * Return: a result based on val in interval [0, ep_ro).
 245 */
 246static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
 247{
 248        return (u32)(((u64) val * ep_ro) >> 32);
 249}
 250
 251#if defined(CONFIG_MMU) && \
 252        (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
 253#define might_fault() __might_fault(__FILE__, __LINE__)
 254void __might_fault(const char *file, int line);
 255#else
 256static inline void might_fault(void) { }
 257#endif
 258
 259extern struct atomic_notifier_head panic_notifier_list;
 260extern long (*panic_blink)(int state);
 261__printf(1, 2)
 262void panic(const char *fmt, ...)
 263        __noreturn __cold;
 264void nmi_panic(struct pt_regs *regs, const char *msg);
 265extern void oops_enter(void);
 266extern void oops_exit(void);
 267void print_oops_end_marker(void);
 268extern int oops_may_print(void);
 269void do_exit(long error_code)
 270        __noreturn;
 271void complete_and_exit(struct completion *, long)
 272        __noreturn;
 273
 274/* Internal, do not use. */
 275int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 276int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 277
 278int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 279int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 280
 281/**
 282 * kstrtoul - convert a string to an unsigned long
 283 * @s: The start of the string. The string must be null-terminated, and may also
 284 *  include a single newline before its terminating null. The first character
 285 *  may also be a plus sign, but not a minus sign.
 286 * @base: The number base to use. The maximum supported base is 16. If base is
 287 *  given as 0, then the base of the string is automatically detected with the
 288 *  conventional semantics - If it begins with 0x the number will be parsed as a
 289 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 290 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 291 * @res: Where to write the result of the conversion on success.
 292 *
 293 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 294 * Used as a replacement for the obsolete simple_strtoull. Return code must
 295 * be checked.
 296*/
 297static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 298{
 299        /*
 300         * We want to shortcut function call, but
 301         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 302         */
 303        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 304            __alignof__(unsigned long) == __alignof__(unsigned long long))
 305                return kstrtoull(s, base, (unsigned long long *)res);
 306        else
 307                return _kstrtoul(s, base, res);
 308}
 309
 310/**
 311 * kstrtol - convert a string to a long
 312 * @s: The start of the string. The string must be null-terminated, and may also
 313 *  include a single newline before its terminating null. The first character
 314 *  may also be a plus sign or a minus sign.
 315 * @base: The number base to use. The maximum supported base is 16. If base is
 316 *  given as 0, then the base of the string is automatically detected with the
 317 *  conventional semantics - If it begins with 0x the number will be parsed as a
 318 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 319 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 320 * @res: Where to write the result of the conversion on success.
 321 *
 322 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 323 * Used as a replacement for the obsolete simple_strtoull. Return code must
 324 * be checked.
 325 */
 326static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 327{
 328        /*
 329         * We want to shortcut function call, but
 330         * __builtin_types_compatible_p(long, long long) = 0.
 331         */
 332        if (sizeof(long) == sizeof(long long) &&
 333            __alignof__(long) == __alignof__(long long))
 334                return kstrtoll(s, base, (long long *)res);
 335        else
 336                return _kstrtol(s, base, res);
 337}
 338
 339int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 340int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 341
 342static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 343{
 344        return kstrtoull(s, base, res);
 345}
 346
 347static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 348{
 349        return kstrtoll(s, base, res);
 350}
 351
 352static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 353{
 354        return kstrtouint(s, base, res);
 355}
 356
 357static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 358{
 359        return kstrtoint(s, base, res);
 360}
 361
 362int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 363int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 364int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 365int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 366int __must_check kstrtobool(const char *s, bool *res);
 367
 368int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 369int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 370int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 371int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 372int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 373int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 374int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 375int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 376int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 377int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 378int __must_check kstrtobool_from_user(const char __user *s, size_t count, bool *res);
 379
 380static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 381{
 382        return kstrtoull_from_user(s, count, base, res);
 383}
 384
 385static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 386{
 387        return kstrtoll_from_user(s, count, base, res);
 388}
 389
 390static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 391{
 392        return kstrtouint_from_user(s, count, base, res);
 393}
 394
 395static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 396{
 397        return kstrtoint_from_user(s, count, base, res);
 398}
 399
 400/* Obsolete, do not use.  Use kstrto<foo> instead */
 401
 402extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 403extern long simple_strtol(const char *,char **,unsigned int);
 404extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 405extern long long simple_strtoll(const char *,char **,unsigned int);
 406
 407extern int num_to_str(char *buf, int size, unsigned long long num);
 408
 409/* lib/printf utilities */
 410
 411extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 412extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 413extern __printf(3, 4)
 414int snprintf(char *buf, size_t size, const char *fmt, ...);
 415extern __printf(3, 0)
 416int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 417extern __printf(3, 4)
 418int scnprintf(char *buf, size_t size, const char *fmt, ...);
 419extern __printf(3, 0)
 420int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 421extern __printf(2, 3) __malloc
 422char *kasprintf(gfp_t gfp, const char *fmt, ...);
 423extern __printf(2, 0) __malloc
 424char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 425extern __printf(2, 0)
 426const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);
 427
 428extern __scanf(2, 3)
 429int sscanf(const char *, const char *, ...);
 430extern __scanf(2, 0)
 431int vsscanf(const char *, const char *, va_list);
 432
 433extern int get_option(char **str, int *pint);
 434extern char *get_options(const char *str, int nints, int *ints);
 435extern unsigned long long memparse(const char *ptr, char **retptr);
 436extern bool parse_option_str(const char *str, const char *option);
 437
 438extern int core_kernel_text(unsigned long addr);
 439extern int core_kernel_data(unsigned long addr);
 440extern int __kernel_text_address(unsigned long addr);
 441extern int kernel_text_address(unsigned long addr);
 442extern int func_ptr_is_kernel_text(void *ptr);
 443
 444unsigned long int_sqrt(unsigned long);
 445
 446extern void bust_spinlocks(int yes);
 447extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 448extern int panic_timeout;
 449extern int panic_on_oops;
 450extern int panic_on_unrecovered_nmi;
 451extern int panic_on_io_nmi;
 452extern int panic_on_warn;
 453extern int sysctl_panic_on_rcu_stall;
 454extern int sysctl_panic_on_stackoverflow;
 455
 456extern bool crash_kexec_post_notifiers;
 457
 458/*
 459 * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
 460 * holds a CPU number which is executing panic() currently. A value of
 461 * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
 462 */
 463extern atomic_t panic_cpu;
 464#define PANIC_CPU_INVALID       -1
 465
 466/*
 467 * Only to be used by arch init code. If the user over-wrote the default
 468 * CONFIG_PANIC_TIMEOUT, honor it.
 469 */
 470static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 471{
 472        if (panic_timeout == arch_default_timeout)
 473                panic_timeout = timeout;
 474}
 475extern const char *print_tainted(void);
 476enum lockdep_ok {
 477        LOCKDEP_STILL_OK,
 478        LOCKDEP_NOW_UNRELIABLE
 479};
 480extern void add_taint(unsigned flag, enum lockdep_ok);
 481extern int test_taint(unsigned flag);
 482extern unsigned long get_taint(void);
 483extern int root_mountflags;
 484
 485extern bool early_boot_irqs_disabled;
 486
 487/* Values used for system_state */
 488extern enum system_states {
 489        SYSTEM_BOOTING,
 490        SYSTEM_RUNNING,
 491        SYSTEM_HALT,
 492        SYSTEM_POWER_OFF,
 493        SYSTEM_RESTART,
 494} system_state;
 495
 496#define TAINT_PROPRIETARY_MODULE        0
 497#define TAINT_FORCED_MODULE             1
 498#define TAINT_CPU_OUT_OF_SPEC           2
 499#define TAINT_FORCED_RMMOD              3
 500#define TAINT_MACHINE_CHECK             4
 501#define TAINT_BAD_PAGE                  5
 502#define TAINT_USER                      6
 503#define TAINT_DIE                       7
 504#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 505#define TAINT_WARN                      9
 506#define TAINT_CRAP                      10
 507#define TAINT_FIRMWARE_WORKAROUND       11
 508#define TAINT_OOT_MODULE                12
 509#define TAINT_UNSIGNED_MODULE           13
 510#define TAINT_SOFTLOCKUP                14
 511#define TAINT_LIVEPATCH                 15
 512
 513extern const char hex_asc[];
 514#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 515#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 516
 517static inline char *hex_byte_pack(char *buf, u8 byte)
 518{
 519        *buf++ = hex_asc_hi(byte);
 520        *buf++ = hex_asc_lo(byte);
 521        return buf;
 522}
 523
 524extern const char hex_asc_upper[];
 525#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 526#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 527
 528static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 529{
 530        *buf++ = hex_asc_upper_hi(byte);
 531        *buf++ = hex_asc_upper_lo(byte);
 532        return buf;
 533}
 534
 535extern int hex_to_bin(char ch);
 536extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 537extern char *bin2hex(char *dst, const void *src, size_t count);
 538
 539bool mac_pton(const char *s, u8 *mac);
 540
 541/*
 542 * General tracing related utility functions - trace_printk(),
 543 * tracing_on/tracing_off and tracing_start()/tracing_stop
 544 *
 545 * Use tracing_on/tracing_off when you want to quickly turn on or off
 546 * tracing. It simply enables or disables the recording of the trace events.
 547 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 548 * file, which gives a means for the kernel and userspace to interact.
 549 * Place a tracing_off() in the kernel where you want tracing to end.
 550 * From user space, examine the trace, and then echo 1 > tracing_on
 551 * to continue tracing.
 552 *
 553 * tracing_stop/tracing_start has slightly more overhead. It is used
 554 * by things like suspend to ram where disabling the recording of the
 555 * trace is not enough, but tracing must actually stop because things
 556 * like calling smp_processor_id() may crash the system.
 557 *
 558 * Most likely, you want to use tracing_on/tracing_off.
 559 */
 560
 561enum ftrace_dump_mode {
 562        DUMP_NONE,
 563        DUMP_ALL,
 564        DUMP_ORIG,
 565};
 566
 567#ifdef CONFIG_TRACING
 568void tracing_on(void);
 569void tracing_off(void);
 570int tracing_is_on(void);
 571void tracing_snapshot(void);
 572void tracing_snapshot_alloc(void);
 573
 574extern void tracing_start(void);
 575extern void tracing_stop(void);
 576
 577static inline __printf(1, 2)
 578void ____trace_printk_check_format(const char *fmt, ...)
 579{
 580}
 581#define __trace_printk_check_format(fmt, args...)                       \
 582do {                                                                    \
 583        if (0)                                                          \
 584                ____trace_printk_check_format(fmt, ##args);             \
 585} while (0)
 586
 587/**
 588 * trace_printk - printf formatting in the ftrace buffer
 589 * @fmt: the printf format for printing
 590 *
 591 * Note: __trace_printk is an internal function for trace_printk and
 592 *       the @ip is passed in via the trace_printk macro.
 593 *
 594 * This function allows a kernel developer to debug fast path sections
 595 * that printk is not appropriate for. By scattering in various
 596 * printk like tracing in the code, a developer can quickly see
 597 * where problems are occurring.
 598 *
 599 * This is intended as a debugging tool for the developer only.
 600 * Please refrain from leaving trace_printks scattered around in
 601 * your code. (Extra memory is used for special buffers that are
 602 * allocated when trace_printk() is used)
 603 *
 604 * A little optization trick is done here. If there's only one
 605 * argument, there's no need to scan the string for printf formats.
 606 * The trace_puts() will suffice. But how can we take advantage of
 607 * using trace_puts() when trace_printk() has only one argument?
 608 * By stringifying the args and checking the size we can tell
 609 * whether or not there are args. __stringify((__VA_ARGS__)) will
 610 * turn into "()\0" with a size of 3 when there are no args, anything
 611 * else will be bigger. All we need to do is define a string to this,
 612 * and then take its size and compare to 3. If it's bigger, use
 613 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 614 * let gcc optimize the rest.
 615 */
 616
 617#define trace_printk(fmt, ...)                          \
 618do {                                                    \
 619        char _______STR[] = __stringify((__VA_ARGS__)); \
 620        if (sizeof(_______STR) > 3)                     \
 621                do_trace_printk(fmt, ##__VA_ARGS__);    \
 622        else                                            \
 623                trace_puts(fmt);                        \
 624} while (0)
 625
 626#define do_trace_printk(fmt, args...)                                   \
 627do {                                                                    \
 628        static const char *trace_printk_fmt __used                      \
 629                __attribute__((section("__trace_printk_fmt"))) =        \
 630                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 631                                                                        \
 632        __trace_printk_check_format(fmt, ##args);                       \
 633                                                                        \
 634        if (__builtin_constant_p(fmt))                                  \
 635                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 636        else                                                            \
 637                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 638} while (0)
 639
 640extern __printf(2, 3)
 641int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 642
 643extern __printf(2, 3)
 644int __trace_printk(unsigned long ip, const char *fmt, ...);
 645
 646/**
 647 * trace_puts - write a string into the ftrace buffer
 648 * @str: the string to record
 649 *
 650 * Note: __trace_bputs is an internal function for trace_puts and
 651 *       the @ip is passed in via the trace_puts macro.
 652 *
 653 * This is similar to trace_printk() but is made for those really fast
 654 * paths that a developer wants the least amount of "Heisenbug" affects,
 655 * where the processing of the print format is still too much.
 656 *
 657 * This function allows a kernel developer to debug fast path sections
 658 * that printk is not appropriate for. By scattering in various
 659 * printk like tracing in the code, a developer can quickly see
 660 * where problems are occurring.
 661 *
 662 * This is intended as a debugging tool for the developer only.
 663 * Please refrain from leaving trace_puts scattered around in
 664 * your code. (Extra memory is used for special buffers that are
 665 * allocated when trace_puts() is used)
 666 *
 667 * Returns: 0 if nothing was written, positive # if string was.
 668 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 669 */
 670
 671#define trace_puts(str) ({                                              \
 672        static const char *trace_printk_fmt __used                      \
 673                __attribute__((section("__trace_printk_fmt"))) =        \
 674                __builtin_constant_p(str) ? str : NULL;                 \
 675                                                                        \
 676        if (__builtin_constant_p(str))                                  \
 677                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 678        else                                                            \
 679                __trace_puts(_THIS_IP_, str, strlen(str));              \
 680})
 681extern int __trace_bputs(unsigned long ip, const char *str);
 682extern int __trace_puts(unsigned long ip, const char *str, int size);
 683
 684extern void trace_dump_stack(int skip);
 685
 686/*
 687 * The double __builtin_constant_p is because gcc will give us an error
 688 * if we try to allocate the static variable to fmt if it is not a
 689 * constant. Even with the outer if statement.
 690 */
 691#define ftrace_vprintk(fmt, vargs)                                      \
 692do {                                                                    \
 693        if (__builtin_constant_p(fmt)) {                                \
 694                static const char *trace_printk_fmt __used              \
 695                  __attribute__((section("__trace_printk_fmt"))) =      \
 696                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 697                                                                        \
 698                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 699        } else                                                          \
 700                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 701} while (0)
 702
 703extern __printf(2, 0) int
 704__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 705
 706extern __printf(2, 0) int
 707__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 708
 709extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 710#else
 711static inline void tracing_start(void) { }
 712static inline void tracing_stop(void) { }
 713static inline void trace_dump_stack(int skip) { }
 714
 715static inline void tracing_on(void) { }
 716static inline void tracing_off(void) { }
 717static inline int tracing_is_on(void) { return 0; }
 718static inline void tracing_snapshot(void) { }
 719static inline void tracing_snapshot_alloc(void) { }
 720
 721static inline __printf(1, 2)
 722int trace_printk(const char *fmt, ...)
 723{
 724        return 0;
 725}
 726static __printf(1, 0) inline int
 727ftrace_vprintk(const char *fmt, va_list ap)
 728{
 729        return 0;
 730}
 731static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 732#endif /* CONFIG_TRACING */
 733
 734/*
 735 * min()/max()/clamp() macros that also do
 736 * strict type-checking.. See the
 737 * "unnecessary" pointer comparison.
 738 */
 739#define min(x, y) ({                            \
 740        typeof(x) _min1 = (x);                  \
 741        typeof(y) _min2 = (y);                  \
 742        (void) (&_min1 == &_min2);              \
 743        _min1 < _min2 ? _min1 : _min2; })
 744
 745#define max(x, y) ({                            \
 746        typeof(x) _max1 = (x);                  \
 747        typeof(y) _max2 = (y);                  \
 748        (void) (&_max1 == &_max2);              \
 749        _max1 > _max2 ? _max1 : _max2; })
 750
 751#define min3(x, y, z) min((typeof(x))min(x, y), z)
 752#define max3(x, y, z) max((typeof(x))max(x, y), z)
 753
 754/**
 755 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 756 * @x: value1
 757 * @y: value2
 758 */
 759#define min_not_zero(x, y) ({                   \
 760        typeof(x) __x = (x);                    \
 761        typeof(y) __y = (y);                    \
 762        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 763
 764/**
 765 * clamp - return a value clamped to a given range with strict typechecking
 766 * @val: current value
 767 * @lo: lowest allowable value
 768 * @hi: highest allowable value
 769 *
 770 * This macro does strict typechecking of lo/hi to make sure they are of the
 771 * same type as val.  See the unnecessary pointer comparisons.
 772 */
 773#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
 774
 775/*
 776 * ..and if you can't take the strict
 777 * types, you can specify one yourself.
 778 *
 779 * Or not use min/max/clamp at all, of course.
 780 */
 781#define min_t(type, x, y) ({                    \
 782        type __min1 = (x);                      \
 783        type __min2 = (y);                      \
 784        __min1 < __min2 ? __min1: __min2; })
 785
 786#define max_t(type, x, y) ({                    \
 787        type __max1 = (x);                      \
 788        type __max2 = (y);                      \
 789        __max1 > __max2 ? __max1: __max2; })
 790
 791/**
 792 * clamp_t - return a value clamped to a given range using a given type
 793 * @type: the type of variable to use
 794 * @val: current value
 795 * @lo: minimum allowable value
 796 * @hi: maximum allowable value
 797 *
 798 * This macro does no typechecking and uses temporary variables of type
 799 * 'type' to make all the comparisons.
 800 */
 801#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
 802
 803/**
 804 * clamp_val - return a value clamped to a given range using val's type
 805 * @val: current value
 806 * @lo: minimum allowable value
 807 * @hi: maximum allowable value
 808 *
 809 * This macro does no typechecking and uses temporary variables of whatever
 810 * type the input argument 'val' is.  This is useful when val is an unsigned
 811 * type and min and max are literals that will otherwise be assigned a signed
 812 * integer type.
 813 */
 814#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 815
 816
 817/*
 818 * swap - swap value of @a and @b
 819 */
 820#define swap(a, b) \
 821        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 822
 823/**
 824 * container_of - cast a member of a structure out to the containing structure
 825 * @ptr:        the pointer to the member.
 826 * @type:       the type of the container struct this is embedded in.
 827 * @member:     the name of the member within the struct.
 828 *
 829 */
 830#define container_of(ptr, type, member) ({                      \
 831        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 832        (type *)( (char *)__mptr - offsetof(type,member) );})
 833
 834/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 835#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 836# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 837#endif
 838
 839/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
 840#define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
 841        (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
 842         BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
 843         /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
 844         BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
 845         BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
 846         /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
 847         BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
 848         /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
 849         BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
 850         (perms))
 851#endif
 852