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/*
 108 * Multiplies an integer by a fraction, while avoiding unnecessary
 109 * overflow or loss of precision.
 110 */
 111#define mult_frac(x, numer, denom)(                     \
 112{                                                       \
 113        typeof(x) quot = (x) / (denom);                 \
 114        typeof(x) rem  = (x) % (denom);                 \
 115        (quot * (numer)) + ((rem * (numer)) / (denom)); \
 116}                                                       \
 117)
 118
 119
 120#define _RET_IP_                (unsigned long)__builtin_return_address(0)
 121#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 122
 123#ifdef CONFIG_LBDAF
 124# include <asm/div64.h>
 125# define sector_div(a, b) do_div(a, b)
 126#else
 127# define sector_div(n, b)( \
 128{ \
 129        int _res; \
 130        _res = (n) % (b); \
 131        (n) /= (b); \
 132        _res; \
 133} \
 134)
 135#endif
 136
 137/**
 138 * upper_32_bits - return bits 32-63 of a number
 139 * @n: the number we're accessing
 140 *
 141 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 142 * the "right shift count >= width of type" warning when that quantity is
 143 * 32-bits.
 144 */
 145#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 146
 147/**
 148 * lower_32_bits - return bits 0-31 of a number
 149 * @n: the number we're accessing
 150 */
 151#define lower_32_bits(n) ((u32)(n))
 152
 153struct completion;
 154struct pt_regs;
 155struct user;
 156
 157#ifdef CONFIG_PREEMPT_VOLUNTARY
 158extern int _cond_resched(void);
 159# define might_resched() _cond_resched()
 160#else
 161# define might_resched() do { } while (0)
 162#endif
 163
 164#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 165  void __might_sleep(const char *file, int line, int preempt_offset);
 166/**
 167 * might_sleep - annotation for functions that can sleep
 168 *
 169 * this macro will print a stack trace if it is executed in an atomic
 170 * context (spinlock, irq-handler, ...).
 171 *
 172 * This is a useful debugging help to be able to catch problems early and not
 173 * be bitten later when the calling function happens to sleep when it is not
 174 * supposed to.
 175 */
 176# define might_sleep() \
 177        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 178#else
 179  static inline void __might_sleep(const char *file, int line,
 180                                   int preempt_offset) { }
 181# define might_sleep() do { might_resched(); } while (0)
 182#endif
 183
 184#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 185
 186/*
 187 * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
 188 * input types abs() returns a signed long.
 189 * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 190 * for those.
 191 */
 192#define abs(x) ({                                               \
 193                long ret;                                       \
 194                if (sizeof(x) == sizeof(long)) {                \
 195                        long __x = (x);                         \
 196                        ret = (__x < 0) ? -__x : __x;           \
 197                } else {                                        \
 198                        int __x = (x);                          \
 199                        ret = (__x < 0) ? -__x : __x;           \
 200                }                                               \
 201                ret;                                            \
 202        })
 203
 204#define abs64(x) ({                             \
 205                s64 __x = (x);                  \
 206                (__x < 0) ? -__x : __x;         \
 207        })
 208
 209/**
 210 * reciprocal_scale - "scale" a value into range [0, ep_ro)
 211 * @val: value
 212 * @ep_ro: right open interval endpoint
 213 *
 214 * Perform a "reciprocal multiplication" in order to "scale" a value into
 215 * range [0, ep_ro), where the upper interval endpoint is right-open.
 216 * This is useful, e.g. for accessing a index of an array containing
 217 * ep_ro elements, for example. Think of it as sort of modulus, only that
 218 * the result isn't that of modulo. ;) Note that if initial input is a
 219 * small value, then result will return 0.
 220 *
 221 * Return: a result based on val in interval [0, ep_ro).
 222 */
 223static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
 224{
 225        return (u32)(((u64) val * ep_ro) >> 32);
 226}
 227
 228#if defined(CONFIG_MMU) && \
 229        (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
 230void might_fault(void);
 231#else
 232static inline void might_fault(void) { }
 233#endif
 234
 235extern struct atomic_notifier_head panic_notifier_list;
 236extern long (*panic_blink)(int state);
 237__printf(1, 2)
 238void panic(const char *fmt, ...)
 239        __noreturn __cold;
 240extern void oops_enter(void);
 241extern void oops_exit(void);
 242void print_oops_end_marker(void);
 243extern int oops_may_print(void);
 244void do_exit(long error_code)
 245        __noreturn;
 246void complete_and_exit(struct completion *, long)
 247        __noreturn;
 248
 249/* Internal, do not use. */
 250int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 251int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 252
 253int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 254int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 255
 256/**
 257 * kstrtoul - convert a string to an unsigned long
 258 * @s: The start of the string. The string must be null-terminated, and may also
 259 *  include a single newline before its terminating null. The first character
 260 *  may also be a plus sign, but not a minus sign.
 261 * @base: The number base to use. The maximum supported base is 16. If base is
 262 *  given as 0, then the base of the string is automatically detected with the
 263 *  conventional semantics - If it begins with 0x the number will be parsed as a
 264 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 265 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 266 * @res: Where to write the result of the conversion on success.
 267 *
 268 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 269 * Used as a replacement for the obsolete simple_strtoull. Return code must
 270 * be checked.
 271*/
 272static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 273{
 274        /*
 275         * We want to shortcut function call, but
 276         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 277         */
 278        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 279            __alignof__(unsigned long) == __alignof__(unsigned long long))
 280                return kstrtoull(s, base, (unsigned long long *)res);
 281        else
 282                return _kstrtoul(s, base, res);
 283}
 284
 285/**
 286 * kstrtol - convert a string to a long
 287 * @s: The start of the string. The string must be null-terminated, and may also
 288 *  include a single newline before its terminating null. The first character
 289 *  may also be a plus sign or a minus sign.
 290 * @base: The number base to use. The maximum supported base is 16. If base is
 291 *  given as 0, then the base of the string is automatically detected with the
 292 *  conventional semantics - If it begins with 0x the number will be parsed as a
 293 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 294 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 295 * @res: Where to write the result of the conversion on success.
 296 *
 297 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 298 * Used as a replacement for the obsolete simple_strtoull. Return code must
 299 * be checked.
 300 */
 301static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 302{
 303        /*
 304         * We want to shortcut function call, but
 305         * __builtin_types_compatible_p(long, long long) = 0.
 306         */
 307        if (sizeof(long) == sizeof(long long) &&
 308            __alignof__(long) == __alignof__(long long))
 309                return kstrtoll(s, base, (long long *)res);
 310        else
 311                return _kstrtol(s, base, res);
 312}
 313
 314int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 315int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 316
 317static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 318{
 319        return kstrtoull(s, base, res);
 320}
 321
 322static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 323{
 324        return kstrtoll(s, base, res);
 325}
 326
 327static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 328{
 329        return kstrtouint(s, base, res);
 330}
 331
 332static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 333{
 334        return kstrtoint(s, base, res);
 335}
 336
 337int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 338int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 339int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 340int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 341
 342int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 343int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 344int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 345int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 346int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 347int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 348int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 349int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 350int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 351int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 352
 353static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 354{
 355        return kstrtoull_from_user(s, count, base, res);
 356}
 357
 358static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 359{
 360        return kstrtoll_from_user(s, count, base, res);
 361}
 362
 363static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 364{
 365        return kstrtouint_from_user(s, count, base, res);
 366}
 367
 368static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 369{
 370        return kstrtoint_from_user(s, count, base, res);
 371}
 372
 373/* Obsolete, do not use.  Use kstrto<foo> instead */
 374
 375extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 376extern long simple_strtol(const char *,char **,unsigned int);
 377extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 378extern long long simple_strtoll(const char *,char **,unsigned int);
 379#define strict_strtoul  kstrtoul
 380#define strict_strtol   kstrtol
 381#define strict_strtoull kstrtoull
 382#define strict_strtoll  kstrtoll
 383
 384extern int num_to_str(char *buf, int size, unsigned long long num);
 385
 386/* lib/printf utilities */
 387
 388extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 389extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 390extern __printf(3, 4)
 391int snprintf(char *buf, size_t size, const char *fmt, ...);
 392extern __printf(3, 0)
 393int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 394extern __printf(3, 4)
 395int scnprintf(char *buf, size_t size, const char *fmt, ...);
 396extern __printf(3, 0)
 397int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 398extern __printf(2, 3)
 399char *kasprintf(gfp_t gfp, const char *fmt, ...);
 400extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 401
 402extern __scanf(2, 3)
 403int sscanf(const char *, const char *, ...);
 404extern __scanf(2, 0)
 405int vsscanf(const char *, const char *, va_list);
 406
 407extern int get_option(char **str, int *pint);
 408extern char *get_options(const char *str, int nints, int *ints);
 409extern unsigned long long memparse(const char *ptr, char **retptr);
 410
 411extern int core_kernel_text(unsigned long addr);
 412extern int core_kernel_data(unsigned long addr);
 413extern int __kernel_text_address(unsigned long addr);
 414extern int kernel_text_address(unsigned long addr);
 415extern int func_ptr_is_kernel_text(void *ptr);
 416
 417struct pid;
 418extern struct pid *session_of_pgrp(struct pid *pgrp);
 419
 420unsigned long int_sqrt(unsigned long);
 421
 422extern void bust_spinlocks(int yes);
 423extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 424extern int panic_timeout;
 425extern int panic_on_oops;
 426extern int panic_on_unrecovered_nmi;
 427extern int panic_on_io_nmi;
 428extern int sysctl_panic_on_stackoverflow;
 429/*
 430 * Only to be used by arch init code. If the user over-wrote the default
 431 * CONFIG_PANIC_TIMEOUT, honor it.
 432 */
 433static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 434{
 435        if (panic_timeout == arch_default_timeout)
 436                panic_timeout = timeout;
 437}
 438extern const char *print_tainted(void);
 439enum lockdep_ok {
 440        LOCKDEP_STILL_OK,
 441        LOCKDEP_NOW_UNRELIABLE
 442};
 443extern void add_taint(unsigned flag, enum lockdep_ok);
 444extern int test_taint(unsigned flag);
 445extern unsigned long get_taint(void);
 446extern int root_mountflags;
 447
 448extern bool early_boot_irqs_disabled;
 449
 450/* Values used for system_state */
 451extern enum system_states {
 452        SYSTEM_BOOTING,
 453        SYSTEM_RUNNING,
 454        SYSTEM_HALT,
 455        SYSTEM_POWER_OFF,
 456        SYSTEM_RESTART,
 457} system_state;
 458
 459#define TAINT_PROPRIETARY_MODULE        0
 460#define TAINT_FORCED_MODULE             1
 461#define TAINT_UNSAFE_SMP                2
 462#define TAINT_FORCED_RMMOD              3
 463#define TAINT_MACHINE_CHECK             4
 464#define TAINT_BAD_PAGE                  5
 465#define TAINT_USER                      6
 466#define TAINT_DIE                       7
 467#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 468#define TAINT_WARN                      9
 469#define TAINT_CRAP                      10
 470#define TAINT_FIRMWARE_WORKAROUND       11
 471#define TAINT_OOT_MODULE                12
 472
 473extern const char hex_asc[];
 474#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 475#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 476
 477static inline char *hex_byte_pack(char *buf, u8 byte)
 478{
 479        *buf++ = hex_asc_hi(byte);
 480        *buf++ = hex_asc_lo(byte);
 481        return buf;
 482}
 483
 484extern const char hex_asc_upper[];
 485#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 486#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 487
 488static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 489{
 490        *buf++ = hex_asc_upper_hi(byte);
 491        *buf++ = hex_asc_upper_lo(byte);
 492        return buf;
 493}
 494
 495static inline char * __deprecated pack_hex_byte(char *buf, u8 byte)
 496{
 497        return hex_byte_pack(buf, byte);
 498}
 499
 500extern int hex_to_bin(char ch);
 501extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 502
 503int mac_pton(const char *s, u8 *mac);
 504
 505/*
 506 * General tracing related utility functions - trace_printk(),
 507 * tracing_on/tracing_off and tracing_start()/tracing_stop
 508 *
 509 * Use tracing_on/tracing_off when you want to quickly turn on or off
 510 * tracing. It simply enables or disables the recording of the trace events.
 511 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 512 * file, which gives a means for the kernel and userspace to interact.
 513 * Place a tracing_off() in the kernel where you want tracing to end.
 514 * From user space, examine the trace, and then echo 1 > tracing_on
 515 * to continue tracing.
 516 *
 517 * tracing_stop/tracing_start has slightly more overhead. It is used
 518 * by things like suspend to ram where disabling the recording of the
 519 * trace is not enough, but tracing must actually stop because things
 520 * like calling smp_processor_id() may crash the system.
 521 *
 522 * Most likely, you want to use tracing_on/tracing_off.
 523 */
 524#ifdef CONFIG_RING_BUFFER
 525/* trace_off_permanent stops recording with no way to bring it back */
 526void tracing_off_permanent(void);
 527#else
 528static inline void tracing_off_permanent(void) { }
 529#endif
 530
 531enum ftrace_dump_mode {
 532        DUMP_NONE,
 533        DUMP_ALL,
 534        DUMP_ORIG,
 535};
 536
 537#ifdef CONFIG_TRACING
 538void tracing_on(void);
 539void tracing_off(void);
 540int tracing_is_on(void);
 541void tracing_snapshot(void);
 542void tracing_snapshot_alloc(void);
 543
 544extern void tracing_start(void);
 545extern void tracing_stop(void);
 546
 547static inline __printf(1, 2)
 548void ____trace_printk_check_format(const char *fmt, ...)
 549{
 550}
 551#define __trace_printk_check_format(fmt, args...)                       \
 552do {                                                                    \
 553        if (0)                                                          \
 554                ____trace_printk_check_format(fmt, ##args);             \
 555} while (0)
 556
 557/**
 558 * trace_printk - printf formatting in the ftrace buffer
 559 * @fmt: the printf format for printing
 560 *
 561 * Note: __trace_printk is an internal function for trace_printk and
 562 *       the @ip is passed in via the trace_printk macro.
 563 *
 564 * This function allows a kernel developer to debug fast path sections
 565 * that printk is not appropriate for. By scattering in various
 566 * printk like tracing in the code, a developer can quickly see
 567 * where problems are occurring.
 568 *
 569 * This is intended as a debugging tool for the developer only.
 570 * Please refrain from leaving trace_printks scattered around in
 571 * your code. (Extra memory is used for special buffers that are
 572 * allocated when trace_printk() is used)
 573 *
 574 * A little optization trick is done here. If there's only one
 575 * argument, there's no need to scan the string for printf formats.
 576 * The trace_puts() will suffice. But how can we take advantage of
 577 * using trace_puts() when trace_printk() has only one argument?
 578 * By stringifying the args and checking the size we can tell
 579 * whether or not there are args. __stringify((__VA_ARGS__)) will
 580 * turn into "()\0" with a size of 3 when there are no args, anything
 581 * else will be bigger. All we need to do is define a string to this,
 582 * and then take its size and compare to 3. If it's bigger, use
 583 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 584 * let gcc optimize the rest.
 585 */
 586
 587#define trace_printk(fmt, ...)                          \
 588do {                                                    \
 589        char _______STR[] = __stringify((__VA_ARGS__)); \
 590        if (sizeof(_______STR) > 3)                     \
 591                do_trace_printk(fmt, ##__VA_ARGS__);    \
 592        else                                            \
 593                trace_puts(fmt);                        \
 594} while (0)
 595
 596#define do_trace_printk(fmt, args...)                                   \
 597do {                                                                    \
 598        static const char *trace_printk_fmt                             \
 599                __attribute__((section("__trace_printk_fmt"))) =        \
 600                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 601                                                                        \
 602        __trace_printk_check_format(fmt, ##args);                       \
 603                                                                        \
 604        if (__builtin_constant_p(fmt))                                  \
 605                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 606        else                                                            \
 607                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 608} while (0)
 609
 610extern __printf(2, 3)
 611int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 612
 613extern __printf(2, 3)
 614int __trace_printk(unsigned long ip, const char *fmt, ...);
 615
 616/**
 617 * trace_puts - write a string into the ftrace buffer
 618 * @str: the string to record
 619 *
 620 * Note: __trace_bputs is an internal function for trace_puts and
 621 *       the @ip is passed in via the trace_puts macro.
 622 *
 623 * This is similar to trace_printk() but is made for those really fast
 624 * paths that a developer wants the least amount of "Heisenbug" affects,
 625 * where the processing of the print format is still too much.
 626 *
 627 * This function allows a kernel developer to debug fast path sections
 628 * that printk is not appropriate for. By scattering in various
 629 * printk like tracing in the code, a developer can quickly see
 630 * where problems are occurring.
 631 *
 632 * This is intended as a debugging tool for the developer only.
 633 * Please refrain from leaving trace_puts scattered around in
 634 * your code. (Extra memory is used for special buffers that are
 635 * allocated when trace_puts() is used)
 636 *
 637 * Returns: 0 if nothing was written, positive # if string was.
 638 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 639 */
 640
 641#define trace_puts(str) ({                                              \
 642        static const char *trace_printk_fmt                             \
 643                __attribute__((section("__trace_printk_fmt"))) =        \
 644                __builtin_constant_p(str) ? str : NULL;                 \
 645                                                                        \
 646        if (__builtin_constant_p(str))                                  \
 647                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 648        else                                                            \
 649                __trace_puts(_THIS_IP_, str, strlen(str));              \
 650})
 651extern int __trace_bputs(unsigned long ip, const char *str);
 652extern int __trace_puts(unsigned long ip, const char *str, int size);
 653
 654extern void trace_dump_stack(int skip);
 655
 656/*
 657 * The double __builtin_constant_p is because gcc will give us an error
 658 * if we try to allocate the static variable to fmt if it is not a
 659 * constant. Even with the outer if statement.
 660 */
 661#define ftrace_vprintk(fmt, vargs)                                      \
 662do {                                                                    \
 663        if (__builtin_constant_p(fmt)) {                                \
 664                static const char *trace_printk_fmt                     \
 665                  __attribute__((section("__trace_printk_fmt"))) =      \
 666                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 667                                                                        \
 668                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 669        } else                                                          \
 670                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 671} while (0)
 672
 673extern int
 674__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 675
 676extern int
 677__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 678
 679extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 680#else
 681static inline void tracing_start(void) { }
 682static inline void tracing_stop(void) { }
 683static inline void trace_dump_stack(int skip) { }
 684
 685static inline void tracing_on(void) { }
 686static inline void tracing_off(void) { }
 687static inline int tracing_is_on(void) { return 0; }
 688static inline void tracing_snapshot(void) { }
 689static inline void tracing_snapshot_alloc(void) { }
 690
 691static inline __printf(1, 2)
 692int trace_printk(const char *fmt, ...)
 693{
 694        return 0;
 695}
 696static inline int
 697ftrace_vprintk(const char *fmt, va_list ap)
 698{
 699        return 0;
 700}
 701static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 702#endif /* CONFIG_TRACING */
 703
 704/*
 705 * min()/max()/clamp() macros that also do
 706 * strict type-checking.. See the
 707 * "unnecessary" pointer comparison.
 708 */
 709#define min(x, y) ({                            \
 710        typeof(x) _min1 = (x);                  \
 711        typeof(y) _min2 = (y);                  \
 712        (void) (&_min1 == &_min2);              \
 713        _min1 < _min2 ? _min1 : _min2; })
 714
 715#define max(x, y) ({                            \
 716        typeof(x) _max1 = (x);                  \
 717        typeof(y) _max2 = (y);                  \
 718        (void) (&_max1 == &_max2);              \
 719        _max1 > _max2 ? _max1 : _max2; })
 720
 721#define min3(x, y, z) ({                        \
 722        typeof(x) _min1 = (x);                  \
 723        typeof(y) _min2 = (y);                  \
 724        typeof(z) _min3 = (z);                  \
 725        (void) (&_min1 == &_min2);              \
 726        (void) (&_min1 == &_min3);              \
 727        _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
 728                (_min2 < _min3 ? _min2 : _min3); })
 729
 730#define max3(x, y, z) ({                        \
 731        typeof(x) _max1 = (x);                  \
 732        typeof(y) _max2 = (y);                  \
 733        typeof(z) _max3 = (z);                  \
 734        (void) (&_max1 == &_max2);              \
 735        (void) (&_max1 == &_max3);              \
 736        _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
 737                (_max2 > _max3 ? _max2 : _max3); })
 738
 739/**
 740 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 741 * @x: value1
 742 * @y: value2
 743 */
 744#define min_not_zero(x, y) ({                   \
 745        typeof(x) __x = (x);                    \
 746        typeof(y) __y = (y);                    \
 747        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 748
 749/**
 750 * clamp - return a value clamped to a given range with strict typechecking
 751 * @val: current value
 752 * @min: minimum allowable value
 753 * @max: maximum allowable value
 754 *
 755 * This macro does strict typechecking of min/max to make sure they are of the
 756 * same type as val.  See the unnecessary pointer comparisons.
 757 */
 758#define clamp(val, min, max) ({                 \
 759        typeof(val) __val = (val);              \
 760        typeof(min) __min = (min);              \
 761        typeof(max) __max = (max);              \
 762        (void) (&__val == &__min);              \
 763        (void) (&__val == &__max);              \
 764        __val = __val < __min ? __min: __val;   \
 765        __val > __max ? __max: __val; })
 766
 767/*
 768 * ..and if you can't take the strict
 769 * types, you can specify one yourself.
 770 *
 771 * Or not use min/max/clamp at all, of course.
 772 */
 773#define min_t(type, x, y) ({                    \
 774        type __min1 = (x);                      \
 775        type __min2 = (y);                      \
 776        __min1 < __min2 ? __min1: __min2; })
 777
 778#define max_t(type, x, y) ({                    \
 779        type __max1 = (x);                      \
 780        type __max2 = (y);                      \
 781        __max1 > __max2 ? __max1: __max2; })
 782
 783/**
 784 * clamp_t - return a value clamped to a given range using a given type
 785 * @type: the type of variable to use
 786 * @val: current value
 787 * @min: minimum allowable value
 788 * @max: maximum allowable value
 789 *
 790 * This macro does no typechecking and uses temporary variables of type
 791 * 'type' to make all the comparisons.
 792 */
 793#define clamp_t(type, val, min, max) ({         \
 794        type __val = (val);                     \
 795        type __min = (min);                     \
 796        type __max = (max);                     \
 797        __val = __val < __min ? __min: __val;   \
 798        __val > __max ? __max: __val; })
 799
 800/**
 801 * clamp_val - return a value clamped to a given range using val's type
 802 * @val: current value
 803 * @min: minimum allowable value
 804 * @max: maximum allowable value
 805 *
 806 * This macro does no typechecking and uses temporary variables of whatever
 807 * type the input argument 'val' is.  This is useful when val is an unsigned
 808 * type and min and max are literals that will otherwise be assigned a signed
 809 * integer type.
 810 */
 811#define clamp_val(val, min, max) ({             \
 812        typeof(val) __val = (val);              \
 813        typeof(val) __min = (min);              \
 814        typeof(val) __max = (max);              \
 815        __val = __val < __min ? __min: __val;   \
 816        __val > __max ? __max: __val; })
 817
 818
 819/*
 820 * swap - swap value of @a and @b
 821 */
 822#define swap(a, b) \
 823        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 824
 825/**
 826 * container_of - cast a member of a structure out to the containing structure
 827 * @ptr:        the pointer to the member.
 828 * @type:       the type of the container struct this is embedded in.
 829 * @member:     the name of the member within the struct.
 830 *
 831 */
 832#define container_of(ptr, type, member) ({                      \
 833        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 834        (type *)( (char *)__mptr - offsetof(type,member) );})
 835
 836/* Trap pasters of __FUNCTION__ at compile-time */
 837#define __FUNCTION__ (__func__)
 838
 839/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 840#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 841# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 842#endif
 843
 844#endif
 845
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