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 <linux/dynamic_debug.h>
  15#include <asm/byteorder.h>
  16#include <uapi/linux/kernel.h>
  17
  18#define USHRT_MAX       ((u16)(~0U))
  19#define SHRT_MAX        ((s16)(USHRT_MAX>>1))
  20#define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
  21#define INT_MAX         ((int)(~0U>>1))
  22#define INT_MIN         (-INT_MAX - 1)
  23#define UINT_MAX        (~0U)
  24#define LONG_MAX        ((long)(~0UL>>1))
  25#define LONG_MIN        (-LONG_MAX - 1)
  26#define ULONG_MAX       (~0UL)
  27#define LLONG_MAX       ((long long)(~0ULL>>1))
  28#define LLONG_MIN       (-LLONG_MAX - 1)
  29#define ULLONG_MAX      (~0ULL)
  30#define SIZE_MAX        (~(size_t)0)
  31
  32#define U8_MAX          ((u8)~0U)
  33#define S8_MAX          ((s8)(U8_MAX>>1))
  34#define S8_MIN          ((s8)(-S8_MAX - 1))
  35#define U16_MAX         ((u16)~0U)
  36#define S16_MAX         ((s16)(U16_MAX>>1))
  37#define S16_MIN         ((s16)(-S16_MAX - 1))
  38#define U32_MAX         ((u32)~0U)
  39#define S32_MAX         ((s32)(U32_MAX>>1))
  40#define S32_MIN         ((s32)(-S32_MAX - 1))
  41#define U64_MAX         ((u64)~0ULL)
  42#define S64_MAX         ((s64)(U64_MAX>>1))
  43#define S64_MIN         ((s64)(-S64_MAX - 1))
  44
  45#define STACK_MAGIC     0xdeadbeef
  46
  47#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
  48
  49#define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
  50#define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
  51#define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  52#define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  53
  54#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  55
  56/*
  57 * This looks more complex than it should be. But we need to
  58 * get the type for the ~ right in round_down (it needs to be
  59 * as wide as the result!), and we want to evaluate the macro
  60 * arguments just once each.
  61 */
  62#define __round_mask(x, y) ((__typeof__(x))((y)-1))
  63#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
  64#define round_down(x, y) ((x) & ~__round_mask(x, y))
  65
  66#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  67#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  68#define DIV_ROUND_UP_ULL(ll,d) \
  69        ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
  70
  71#if BITS_PER_LONG == 32
  72# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
  73#else
  74# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
  75#endif
  76
  77/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
  78#define roundup(x, y) (                                 \
  79{                                                       \
  80        const typeof(y) __y = y;                        \
  81        (((x) + (__y - 1)) / __y) * __y;                \
  82}                                                       \
  83)
  84#define rounddown(x, y) (                               \
  85{                                                       \
  86        typeof(x) __x = (x);                            \
  87        __x - (__x % (y));                              \
  88}                                                       \
  89)
  90
  91/*
  92 * Divide positive or negative dividend by positive divisor and round
  93 * to closest integer. Result is undefined for negative divisors and
  94 * for negative dividends if the divisor variable type is unsigned.
  95 */
  96#define DIV_ROUND_CLOSEST(x, divisor)(                  \
  97{                                                       \
  98        typeof(x) __x = x;                              \
  99        typeof(divisor) __d = divisor;                  \
 100        (((typeof(x))-1) > 0 ||                         \
 101         ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
 102                (((__x) + ((__d) / 2)) / (__d)) :       \
 103                (((__x) - ((__d) / 2)) / (__d));        \
 104}                                                       \
 105)
 106/*
 107 * Same as above but for u64 dividends. divisor must be a 32-bit
 108 * number.
 109 */
 110#define DIV_ROUND_CLOSEST_ULL(x, divisor)(              \
 111{                                                       \
 112        typeof(divisor) __d = divisor;                  \
 113        unsigned long long _tmp = (x) + (__d) / 2;      \
 114        do_div(_tmp, __d);                              \
 115        _tmp;                                           \
 116}                                                       \
 117)
 118
 119/*
 120 * Multiplies an integer by a fraction, while avoiding unnecessary
 121 * overflow or loss of precision.
 122 */
 123#define mult_frac(x, numer, denom)(                     \
 124{                                                       \
 125        typeof(x) quot = (x) / (denom);                 \
 126        typeof(x) rem  = (x) % (denom);                 \
 127        (quot * (numer)) + ((rem * (numer)) / (denom)); \
 128}                                                       \
 129)
 130
 131
 132#define _RET_IP_                (unsigned long)__builtin_return_address(0)
 133#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 134
 135#ifdef CONFIG_LBDAF
 136# include <asm/div64.h>
 137# define sector_div(a, b) do_div(a, b)
 138#else
 139# define sector_div(n, b)( \
 140{ \
 141        int _res; \
 142        _res = (n) % (b); \
 143        (n) /= (b); \
 144        _res; \
 145} \
 146)
 147#endif
 148
 149/**
 150 * upper_32_bits - return bits 32-63 of a number
 151 * @n: the number we're accessing
 152 *
 153 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 154 * the "right shift count >= width of type" warning when that quantity is
 155 * 32-bits.
 156 */
 157#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 158
 159/**
 160 * lower_32_bits - return bits 0-31 of a number
 161 * @n: the number we're accessing
 162 */
 163#define lower_32_bits(n) ((u32)(n))
 164
 165struct completion;
 166struct pt_regs;
 167struct user;
 168
 169#ifdef CONFIG_PREEMPT_VOLUNTARY
 170extern int _cond_resched(void);
 171# define might_resched() _cond_resched()
 172#else
 173# define might_resched() do { } while (0)
 174#endif
 175
 176#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 177  void ___might_sleep(const char *file, int line, int preempt_offset);
 178  void __might_sleep(const char *file, int line, int preempt_offset);
 179/**
 180 * might_sleep - annotation for functions that can sleep
 181 *
 182 * this macro will print a stack trace if it is executed in an atomic
 183 * context (spinlock, irq-handler, ...).
 184 *
 185 * This is a useful debugging help to be able to catch problems early and not
 186 * be bitten later when the calling function happens to sleep when it is not
 187 * supposed to.
 188 */
 189# define might_sleep() \
 190        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 191# define sched_annotate_sleep() (current->task_state_change = 0)
 192#else
 193  static inline void ___might_sleep(const char *file, int line,
 194                                   int preempt_offset) { }
 195  static inline void __might_sleep(const char *file, int line,
 196                                   int preempt_offset) { }
 197# define might_sleep() do { might_resched(); } while (0)
 198# define sched_annotate_sleep() do { } while (0)
 199#endif
 200
 201#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 202
 203/**
 204 * abs - return absolute value of an argument
 205 * @x: the value.  If it is unsigned type, it is converted to signed type first.
 206 *     char is treated as if it was signed (regardless of whether it really is)
 207 *     but the macro's return type is preserved as char.
 208 *
 209 * Return: an absolute value of x.
 210 */
 211#define abs(x)  __abs_choose_expr(x, long long,                         \
 212                __abs_choose_expr(x, long,                              \
 213                __abs_choose_expr(x, int,                               \
 214                __abs_choose_expr(x, short,                             \
 215                __abs_choose_expr(x, char,                              \
 216                __builtin_choose_expr(                                  \
 217                        __builtin_types_compatible_p(typeof(x), char),  \
 218                        (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
 219                        ((void)0)))))))
 220
 221#define __abs_choose_expr(x, type, other) __builtin_choose_expr(        \
 222        __builtin_types_compatible_p(typeof(x),   signed type) ||       \
 223        __builtin_types_compatible_p(typeof(x), unsigned type),         \
 224        ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
 225
 226/**
 227 * reciprocal_scale - "scale" a value into range [0, ep_ro)
 228 * @val: value
 229 * @ep_ro: right open interval endpoint
 230 *
 231 * Perform a "reciprocal multiplication" in order to "scale" a value into
 232 * range [0, ep_ro), where the upper interval endpoint is right-open.
 233 * This is useful, e.g. for accessing a index of an array containing
 234 * ep_ro elements, for example. Think of it as sort of modulus, only that
 235 * the result isn't that of modulo. ;) Note that if initial input is a
 236 * small value, then result will return 0.
 237 *
 238 * Return: a result based on val in interval [0, ep_ro).
 239 */
 240static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
 241{
 242        return (u32)(((u64) val * ep_ro) >> 32);
 243}
 244
 245#if defined(CONFIG_MMU) && \
 246        (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
 247#define might_fault() __might_fault(__FILE__, __LINE__)
 248void __might_fault(const char *file, int line);
 249#else
 250static inline void might_fault(void) { }
 251#endif
 252
 253extern struct atomic_notifier_head panic_notifier_list;
 254extern long (*panic_blink)(int state);
 255__printf(1, 2)
 256void panic(const char *fmt, ...)
 257        __noreturn __cold;
 258void nmi_panic_self_stop(struct pt_regs *);
 259extern void oops_enter(void);
 260extern void oops_exit(void);
 261void print_oops_end_marker(void);
 262extern int oops_may_print(void);
 263void do_exit(long error_code)
 264        __noreturn;
 265void complete_and_exit(struct completion *, long)
 266        __noreturn;
 267
 268/* Internal, do not use. */
 269int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 270int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 271
 272int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 273int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 274
 275/**
 276 * kstrtoul - convert a string to an unsigned long
 277 * @s: The start of the string. The string must be null-terminated, and may also
 278 *  include a single newline before its terminating null. The first character
 279 *  may also be a plus sign, but not a minus sign.
 280 * @base: The number base to use. The maximum supported base is 16. If base is
 281 *  given as 0, then the base of the string is automatically detected with the
 282 *  conventional semantics - If it begins with 0x the number will be parsed as a
 283 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 284 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 285 * @res: Where to write the result of the conversion on success.
 286 *
 287 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 288 * Used as a replacement for the obsolete simple_strtoull. Return code must
 289 * be checked.
 290*/
 291static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 292{
 293        /*
 294         * We want to shortcut function call, but
 295         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 296         */
 297        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 298            __alignof__(unsigned long) == __alignof__(unsigned long long))
 299                return kstrtoull(s, base, (unsigned long long *)res);
 300        else
 301                return _kstrtoul(s, base, res);
 302}
 303
 304/**
 305 * kstrtol - convert a string to a long
 306 * @s: The start of the string. The string must be null-terminated, and may also
 307 *  include a single newline before its terminating null. The first character
 308 *  may also be a plus sign or a minus sign.
 309 * @base: The number base to use. The maximum supported base is 16. If base is
 310 *  given as 0, then the base of the string is automatically detected with the
 311 *  conventional semantics - If it begins with 0x the number will be parsed as a
 312 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 313 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 314 * @res: Where to write the result of the conversion on success.
 315 *
 316 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 317 * Used as a replacement for the obsolete simple_strtoull. Return code must
 318 * be checked.
 319 */
 320static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 321{
 322        /*
 323         * We want to shortcut function call, but
 324         * __builtin_types_compatible_p(long, long long) = 0.
 325         */
 326        if (sizeof(long) == sizeof(long long) &&
 327            __alignof__(long) == __alignof__(long long))
 328                return kstrtoll(s, base, (long long *)res);
 329        else
 330                return _kstrtol(s, base, res);
 331}
 332
 333int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 334int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 335
 336static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 337{
 338        return kstrtoull(s, base, res);
 339}
 340
 341static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 342{
 343        return kstrtoll(s, base, res);
 344}
 345
 346static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 347{
 348        return kstrtouint(s, base, res);
 349}
 350
 351static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 352{
 353        return kstrtoint(s, base, res);
 354}
 355
 356int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 357int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 358int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 359int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 360
 361int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 362int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 363int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 364int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 365int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 366int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 367int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 368int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 369int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 370int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 371
 372static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 373{
 374        return kstrtoull_from_user(s, count, base, res);
 375}
 376
 377static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 378{
 379        return kstrtoll_from_user(s, count, base, res);
 380}
 381
 382static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 383{
 384        return kstrtouint_from_user(s, count, base, res);
 385}
 386
 387static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 388{
 389        return kstrtoint_from_user(s, count, base, res);
 390}
 391
 392/* Obsolete, do not use.  Use kstrto<foo> instead */
 393
 394extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 395extern long simple_strtol(const char *,char **,unsigned int);
 396extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 397extern long long simple_strtoll(const char *,char **,unsigned int);
 398
 399extern int num_to_str(char *buf, int size, unsigned long long num);
 400
 401/* lib/printf utilities */
 402
 403extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 404extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 405extern __printf(3, 4)
 406int snprintf(char *buf, size_t size, const char *fmt, ...);
 407extern __printf(3, 0)
 408int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 409extern __printf(3, 4)
 410int scnprintf(char *buf, size_t size, const char *fmt, ...);
 411extern __printf(3, 0)
 412int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 413extern __printf(2, 3)
 414char *kasprintf(gfp_t gfp, const char *fmt, ...);
 415extern __printf(2, 0)
 416char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 417extern __printf(2, 0)
 418const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);
 419
 420extern __scanf(2, 3)
 421int sscanf(const char *, const char *, ...);
 422extern __scanf(2, 0)
 423int vsscanf(const char *, const char *, va_list);
 424
 425extern int get_option(char **str, int *pint);
 426extern char *get_options(const char *str, int nints, int *ints);
 427extern unsigned long long memparse(const char *ptr, char **retptr);
 428extern bool parse_option_str(const char *str, const char *option);
 429
 430extern int core_kernel_text(unsigned long addr);
 431extern int core_kernel_data(unsigned long addr);
 432extern int __kernel_text_address(unsigned long addr);
 433extern int kernel_text_address(unsigned long addr);
 434extern int func_ptr_is_kernel_text(void *ptr);
 435
 436unsigned long int_sqrt(unsigned long);
 437
 438extern void bust_spinlocks(int yes);
 439extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 440extern int panic_timeout;
 441extern int panic_on_oops;
 442extern int panic_on_unrecovered_nmi;
 443extern int panic_on_io_nmi;
 444extern int panic_on_warn;
 445extern int sysctl_panic_on_stackoverflow;
 446
 447extern bool crash_kexec_post_notifiers;
 448
 449/*
 450 * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
 451 * holds a CPU number which is executing panic() currently. A value of
 452 * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
 453 */
 454extern atomic_t panic_cpu;
 455#define PANIC_CPU_INVALID       -1
 456
 457/*
 458 * A variant of panic() called from NMI context. We return if we've already
 459 * panicked on this CPU. If another CPU already panicked, loop in
 460 * nmi_panic_self_stop() which can provide architecture dependent code such
 461 * as saving register state for crash dump.
 462 */
 463#define nmi_panic(regs, fmt, ...)                                       \
 464do {                                                                    \
 465        int old_cpu, cpu;                                               \
 466                                                                        \
 467        cpu = raw_smp_processor_id();                                   \
 468        old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);   \
 469                                                                        \
 470        if (old_cpu == PANIC_CPU_INVALID)                               \
 471                panic(fmt, ##__VA_ARGS__);                              \
 472        else if (old_cpu != cpu)                                        \
 473                nmi_panic_self_stop(regs);                              \
 474} while (0)
 475
 476/*
 477 * Only to be used by arch init code. If the user over-wrote the default
 478 * CONFIG_PANIC_TIMEOUT, honor it.
 479 */
 480static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 481{
 482        if (panic_timeout == arch_default_timeout)
 483                panic_timeout = timeout;
 484}
 485extern const char *print_tainted(void);
 486enum lockdep_ok {
 487        LOCKDEP_STILL_OK,
 488        LOCKDEP_NOW_UNRELIABLE
 489};
 490extern void add_taint(unsigned flag, enum lockdep_ok);
 491extern int test_taint(unsigned flag);
 492extern unsigned long get_taint(void);
 493extern int root_mountflags;
 494
 495extern bool early_boot_irqs_disabled;
 496
 497/* Values used for system_state */
 498extern enum system_states {
 499        SYSTEM_BOOTING,
 500        SYSTEM_RUNNING,
 501        SYSTEM_HALT,
 502        SYSTEM_POWER_OFF,
 503        SYSTEM_RESTART,
 504} system_state;
 505
 506#define TAINT_PROPRIETARY_MODULE        0
 507#define TAINT_FORCED_MODULE             1
 508#define TAINT_CPU_OUT_OF_SPEC           2
 509#define TAINT_FORCED_RMMOD              3
 510#define TAINT_MACHINE_CHECK             4
 511#define TAINT_BAD_PAGE                  5
 512#define TAINT_USER                      6
 513#define TAINT_DIE                       7
 514#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 515#define TAINT_WARN                      9
 516#define TAINT_CRAP                      10
 517#define TAINT_FIRMWARE_WORKAROUND       11
 518#define TAINT_OOT_MODULE                12
 519#define TAINT_UNSIGNED_MODULE           13
 520#define TAINT_SOFTLOCKUP                14
 521#define TAINT_LIVEPATCH                 15
 522
 523extern const char hex_asc[];
 524#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 525#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 526
 527static inline char *hex_byte_pack(char *buf, u8 byte)
 528{
 529        *buf++ = hex_asc_hi(byte);
 530        *buf++ = hex_asc_lo(byte);
 531        return buf;
 532}
 533
 534extern const char hex_asc_upper[];
 535#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 536#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 537
 538static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 539{
 540        *buf++ = hex_asc_upper_hi(byte);
 541        *buf++ = hex_asc_upper_lo(byte);
 542        return buf;
 543}
 544
 545extern int hex_to_bin(char ch);
 546extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 547extern char *bin2hex(char *dst, const void *src, size_t count);
 548
 549bool mac_pton(const char *s, u8 *mac);
 550
 551/*
 552 * General tracing related utility functions - trace_printk(),
 553 * tracing_on/tracing_off and tracing_start()/tracing_stop
 554 *
 555 * Use tracing_on/tracing_off when you want to quickly turn on or off
 556 * tracing. It simply enables or disables the recording of the trace events.
 557 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 558 * file, which gives a means for the kernel and userspace to interact.
 559 * Place a tracing_off() in the kernel where you want tracing to end.
 560 * From user space, examine the trace, and then echo 1 > tracing_on
 561 * to continue tracing.
 562 *
 563 * tracing_stop/tracing_start has slightly more overhead. It is used
 564 * by things like suspend to ram where disabling the recording of the
 565 * trace is not enough, but tracing must actually stop because things
 566 * like calling smp_processor_id() may crash the system.
 567 *
 568 * Most likely, you want to use tracing_on/tracing_off.
 569 */
 570
 571enum ftrace_dump_mode {
 572        DUMP_NONE,
 573        DUMP_ALL,
 574        DUMP_ORIG,
 575};
 576
 577#ifdef CONFIG_TRACING
 578void tracing_on(void);
 579void tracing_off(void);
 580int tracing_is_on(void);
 581void tracing_snapshot(void);
 582void tracing_snapshot_alloc(void);
 583
 584extern void tracing_start(void);
 585extern void tracing_stop(void);
 586
 587static inline __printf(1, 2)
 588void ____trace_printk_check_format(const char *fmt, ...)
 589{
 590}
 591#define __trace_printk_check_format(fmt, args...)                       \
 592do {                                                                    \
 593        if (0)                                                          \
 594                ____trace_printk_check_format(fmt, ##args);             \
 595} while (0)
 596
 597/**
 598 * trace_printk - printf formatting in the ftrace buffer
 599 * @fmt: the printf format for printing
 600 *
 601 * Note: __trace_printk is an internal function for trace_printk and
 602 *       the @ip is passed in via the trace_printk macro.
 603 *
 604 * This function allows a kernel developer to debug fast path sections
 605 * that printk is not appropriate for. By scattering in various
 606 * printk like tracing in the code, a developer can quickly see
 607 * where problems are occurring.
 608 *
 609 * This is intended as a debugging tool for the developer only.
 610 * Please refrain from leaving trace_printks scattered around in
 611 * your code. (Extra memory is used for special buffers that are
 612 * allocated when trace_printk() is used)
 613 *
 614 * A little optization trick is done here. If there's only one
 615 * argument, there's no need to scan the string for printf formats.
 616 * The trace_puts() will suffice. But how can we take advantage of
 617 * using trace_puts() when trace_printk() has only one argument?
 618 * By stringifying the args and checking the size we can tell
 619 * whether or not there are args. __stringify((__VA_ARGS__)) will
 620 * turn into "()\0" with a size of 3 when there are no args, anything
 621 * else will be bigger. All we need to do is define a string to this,
 622 * and then take its size and compare to 3. If it's bigger, use
 623 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 624 * let gcc optimize the rest.
 625 */
 626
 627#define trace_printk(fmt, ...)                          \
 628do {                                                    \
 629        char _______STR[] = __stringify((__VA_ARGS__)); \
 630        if (sizeof(_______STR) > 3)                     \
 631                do_trace_printk(fmt, ##__VA_ARGS__);    \
 632        else                                            \
 633                trace_puts(fmt);                        \
 634} while (0)
 635
 636#define do_trace_printk(fmt, args...)                                   \
 637do {                                                                    \
 638        static const char *trace_printk_fmt                             \
 639                __attribute__((section("__trace_printk_fmt"))) =        \
 640                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 641                                                                        \
 642        __trace_printk_check_format(fmt, ##args);                       \
 643                                                                        \
 644        if (__builtin_constant_p(fmt))                                  \
 645                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 646        else                                                            \
 647                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 648} while (0)
 649
 650extern __printf(2, 3)
 651int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 652
 653extern __printf(2, 3)
 654int __trace_printk(unsigned long ip, const char *fmt, ...);
 655
 656/**
 657 * trace_puts - write a string into the ftrace buffer
 658 * @str: the string to record
 659 *
 660 * Note: __trace_bputs is an internal function for trace_puts and
 661 *       the @ip is passed in via the trace_puts macro.
 662 *
 663 * This is similar to trace_printk() but is made for those really fast
 664 * paths that a developer wants the least amount of "Heisenbug" affects,
 665 * where the processing of the print format is still too much.
 666 *
 667 * This function allows a kernel developer to debug fast path sections
 668 * that printk is not appropriate for. By scattering in various
 669 * printk like tracing in the code, a developer can quickly see
 670 * where problems are occurring.
 671 *
 672 * This is intended as a debugging tool for the developer only.
 673 * Please refrain from leaving trace_puts scattered around in
 674 * your code. (Extra memory is used for special buffers that are
 675 * allocated when trace_puts() is used)
 676 *
 677 * Returns: 0 if nothing was written, positive # if string was.
 678 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 679 */
 680
 681#define trace_puts(str) ({                                              \
 682        static const char *trace_printk_fmt                             \
 683                __attribute__((section("__trace_printk_fmt"))) =        \
 684                __builtin_constant_p(str) ? str : NULL;                 \
 685                                                                        \
 686        if (__builtin_constant_p(str))                                  \
 687                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 688        else                                                            \
 689                __trace_puts(_THIS_IP_, str, strlen(str));              \
 690})
 691extern int __trace_bputs(unsigned long ip, const char *str);
 692extern int __trace_puts(unsigned long ip, const char *str, int size);
 693
 694extern void trace_dump_stack(int skip);
 695
 696/*
 697 * The double __builtin_constant_p is because gcc will give us an error
 698 * if we try to allocate the static variable to fmt if it is not a
 699 * constant. Even with the outer if statement.
 700 */
 701#define ftrace_vprintk(fmt, vargs)                                      \
 702do {                                                                    \
 703        if (__builtin_constant_p(fmt)) {                                \
 704                static const char *trace_printk_fmt                     \
 705                  __attribute__((section("__trace_printk_fmt"))) =      \
 706                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 707                                                                        \
 708                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 709        } else                                                          \
 710                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 711} while (0)
 712
 713extern __printf(2, 0) int
 714__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 715
 716extern __printf(2, 0) int
 717__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 718
 719extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 720#else
 721static inline void tracing_start(void) { }
 722static inline void tracing_stop(void) { }
 723static inline void trace_dump_stack(int skip) { }
 724
 725static inline void tracing_on(void) { }
 726static inline void tracing_off(void) { }
 727static inline int tracing_is_on(void) { return 0; }
 728static inline void tracing_snapshot(void) { }
 729static inline void tracing_snapshot_alloc(void) { }
 730
 731static inline __printf(1, 2)
 732int trace_printk(const char *fmt, ...)
 733{
 734        return 0;
 735}
 736static __printf(1, 0) inline int
 737ftrace_vprintk(const char *fmt, va_list ap)
 738{
 739        return 0;
 740}
 741static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 742#endif /* CONFIG_TRACING */
 743
 744/*
 745 * min()/max()/clamp() macros that also do
 746 * strict type-checking.. See the
 747 * "unnecessary" pointer comparison.
 748 */
 749#define min(x, y) ({                            \
 750        typeof(x) _min1 = (x);                  \
 751        typeof(y) _min2 = (y);                  \
 752        (void) (&_min1 == &_min2);              \
 753        _min1 < _min2 ? _min1 : _min2; })
 754
 755#define max(x, y) ({                            \
 756        typeof(x) _max1 = (x);                  \
 757        typeof(y) _max2 = (y);                  \
 758        (void) (&_max1 == &_max2);              \
 759        _max1 > _max2 ? _max1 : _max2; })
 760
 761#define min3(x, y, z) min((typeof(x))min(x, y), z)
 762#define max3(x, y, z) max((typeof(x))max(x, y), z)
 763
 764/**
 765 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 766 * @x: value1
 767 * @y: value2
 768 */
 769#define min_not_zero(x, y) ({                   \
 770        typeof(x) __x = (x);                    \
 771        typeof(y) __y = (y);                    \
 772        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 773
 774/**
 775 * clamp - return a value clamped to a given range with strict typechecking
 776 * @val: current value
 777 * @lo: lowest allowable value
 778 * @hi: highest allowable value
 779 *
 780 * This macro does strict typechecking of lo/hi to make sure they are of the
 781 * same type as val.  See the unnecessary pointer comparisons.
 782 */
 783#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
 784
 785/*
 786 * ..and if you can't take the strict
 787 * types, you can specify one yourself.
 788 *
 789 * Or not use min/max/clamp at all, of course.
 790 */
 791#define min_t(type, x, y) ({                    \
 792        type __min1 = (x);                      \
 793        type __min2 = (y);                      \
 794        __min1 < __min2 ? __min1: __min2; })
 795
 796#define max_t(type, x, y) ({                    \
 797        type __max1 = (x);                      \
 798        type __max2 = (y);                      \
 799        __max1 > __max2 ? __max1: __max2; })
 800
 801/**
 802 * clamp_t - return a value clamped to a given range using a given type
 803 * @type: the type of variable to use
 804 * @val: current value
 805 * @lo: minimum allowable value
 806 * @hi: maximum allowable value
 807 *
 808 * This macro does no typechecking and uses temporary variables of type
 809 * 'type' to make all the comparisons.
 810 */
 811#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
 812
 813/**
 814 * clamp_val - return a value clamped to a given range using val's type
 815 * @val: current value
 816 * @lo: minimum allowable value
 817 * @hi: maximum allowable value
 818 *
 819 * This macro does no typechecking and uses temporary variables of whatever
 820 * type the input argument 'val' is.  This is useful when val is an unsigned
 821 * type and min and max are literals that will otherwise be assigned a signed
 822 * integer type.
 823 */
 824#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 825
 826
 827/*
 828 * swap - swap value of @a and @b
 829 */
 830#define swap(a, b) \
 831        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 832
 833/**
 834 * container_of - cast a member of a structure out to the containing structure
 835 * @ptr:        the pointer to the member.
 836 * @type:       the type of the container struct this is embedded in.
 837 * @member:     the name of the member within the struct.
 838 *
 839 */
 840#define container_of(ptr, type, member) ({                      \
 841        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 842        (type *)( (char *)__mptr - offsetof(type,member) );})
 843
 844/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 845#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 846# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 847#endif
 848
 849/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
 850#define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
 851        (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
 852         BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
 853         /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
 854         BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
 855         BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
 856         /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
 857         BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
 858         /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
 859         BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
 860         (perms))
 861#endif
 862