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() handles unsigned and signed longs, ints, shorts and chars.  For all
 205 * input types abs() returns a signed long.
 206 * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 207 * for those.
 208 */
 209#define abs(x) ({                                               \
 210                long ret;                                       \
 211                if (sizeof(x) == sizeof(long)) {                \
 212                        long __x = (x);                         \
 213                        ret = (__x < 0) ? -__x : __x;           \
 214                } else {                                        \
 215                        int __x = (x);                          \
 216                        ret = (__x < 0) ? -__x : __x;           \
 217                }                                               \
 218                ret;                                            \
 219        })
 220
 221#define abs64(x) ({                             \
 222                s64 __x = (x);                  \
 223                (__x < 0) ? -__x : __x;         \
 224        })
 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;
 258extern void oops_enter(void);
 259extern void oops_exit(void);
 260void print_oops_end_marker(void);
 261extern int oops_may_print(void);
 262void do_exit(long error_code)
 263        __noreturn;
 264void complete_and_exit(struct completion *, long)
 265        __noreturn;
 266
 267/* Internal, do not use. */
 268int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 269int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 270
 271int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 272int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 273
 274/**
 275 * kstrtoul - convert a string to an unsigned long
 276 * @s: The start of the string. The string must be null-terminated, and may also
 277 *  include a single newline before its terminating null. The first character
 278 *  may also be a plus sign, but not a minus sign.
 279 * @base: The number base to use. The maximum supported base is 16. If base is
 280 *  given as 0, then the base of the string is automatically detected with the
 281 *  conventional semantics - If it begins with 0x the number will be parsed as a
 282 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 283 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 284 * @res: Where to write the result of the conversion on success.
 285 *
 286 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 287 * Used as a replacement for the obsolete simple_strtoull. Return code must
 288 * be checked.
 289*/
 290static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 291{
 292        /*
 293         * We want to shortcut function call, but
 294         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 295         */
 296        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 297            __alignof__(unsigned long) == __alignof__(unsigned long long))
 298                return kstrtoull(s, base, (unsigned long long *)res);
 299        else
 300                return _kstrtoul(s, base, res);
 301}
 302
 303/**
 304 * kstrtol - convert a string to a long
 305 * @s: The start of the string. The string must be null-terminated, and may also
 306 *  include a single newline before its terminating null. The first character
 307 *  may also be a plus sign or a minus sign.
 308 * @base: The number base to use. The maximum supported base is 16. If base is
 309 *  given as 0, then the base of the string is automatically detected with the
 310 *  conventional semantics - If it begins with 0x the number will be parsed as a
 311 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 312 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 313 * @res: Where to write the result of the conversion on success.
 314 *
 315 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 316 * Used as a replacement for the obsolete simple_strtoull. Return code must
 317 * be checked.
 318 */
 319static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 320{
 321        /*
 322         * We want to shortcut function call, but
 323         * __builtin_types_compatible_p(long, long long) = 0.
 324         */
 325        if (sizeof(long) == sizeof(long long) &&
 326            __alignof__(long) == __alignof__(long long))
 327                return kstrtoll(s, base, (long long *)res);
 328        else
 329                return _kstrtol(s, base, res);
 330}
 331
 332int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 333int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 334
 335static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 336{
 337        return kstrtoull(s, base, res);
 338}
 339
 340static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 341{
 342        return kstrtoll(s, base, res);
 343}
 344
 345static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 346{
 347        return kstrtouint(s, base, res);
 348}
 349
 350static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 351{
 352        return kstrtoint(s, base, res);
 353}
 354
 355int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 356int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 357int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 358int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 359
 360int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 361int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 362int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 363int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 364int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 365int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 366int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 367int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 368int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 369int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 370
 371static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 372{
 373        return kstrtoull_from_user(s, count, base, res);
 374}
 375
 376static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 377{
 378        return kstrtoll_from_user(s, count, base, res);
 379}
 380
 381static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 382{
 383        return kstrtouint_from_user(s, count, base, res);
 384}
 385
 386static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 387{
 388        return kstrtoint_from_user(s, count, base, res);
 389}
 390
 391/* Obsolete, do not use.  Use kstrto<foo> instead */
 392
 393extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 394extern long simple_strtol(const char *,char **,unsigned int);
 395extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 396extern long long simple_strtoll(const char *,char **,unsigned int);
 397
 398extern int num_to_str(char *buf, int size, unsigned long long num);
 399
 400/* lib/printf utilities */
 401
 402extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 403extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 404extern __printf(3, 4)
 405int snprintf(char *buf, size_t size, const char *fmt, ...);
 406extern __printf(3, 0)
 407int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 408extern __printf(3, 4)
 409int scnprintf(char *buf, size_t size, const char *fmt, ...);
 410extern __printf(3, 0)
 411int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 412extern __printf(2, 3)
 413char *kasprintf(gfp_t gfp, const char *fmt, ...);
 414extern __printf(2, 0)
 415char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 416
 417extern __scanf(2, 3)
 418int sscanf(const char *, const char *, ...);
 419extern __scanf(2, 0)
 420int vsscanf(const char *, const char *, va_list);
 421
 422extern int get_option(char **str, int *pint);
 423extern char *get_options(const char *str, int nints, int *ints);
 424extern unsigned long long memparse(const char *ptr, char **retptr);
 425extern bool parse_option_str(const char *str, const char *option);
 426
 427extern int core_kernel_text(unsigned long addr);
 428extern int core_kernel_data(unsigned long addr);
 429extern int __kernel_text_address(unsigned long addr);
 430extern int kernel_text_address(unsigned long addr);
 431extern int func_ptr_is_kernel_text(void *ptr);
 432
 433unsigned long int_sqrt(unsigned long);
 434
 435extern void bust_spinlocks(int yes);
 436extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 437extern int panic_timeout;
 438extern int panic_on_oops;
 439extern int panic_on_unrecovered_nmi;
 440extern int panic_on_io_nmi;
 441extern int panic_on_warn;
 442extern int sysctl_panic_on_stackoverflow;
 443
 444extern bool crash_kexec_post_notifiers;
 445
 446/*
 447 * Only to be used by arch init code. If the user over-wrote the default
 448 * CONFIG_PANIC_TIMEOUT, honor it.
 449 */
 450static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 451{
 452        if (panic_timeout == arch_default_timeout)
 453                panic_timeout = timeout;
 454}
 455extern const char *print_tainted(void);
 456enum lockdep_ok {
 457        LOCKDEP_STILL_OK,
 458        LOCKDEP_NOW_UNRELIABLE
 459};
 460extern void add_taint(unsigned flag, enum lockdep_ok);
 461extern int test_taint(unsigned flag);
 462extern unsigned long get_taint(void);
 463extern int root_mountflags;
 464
 465extern bool early_boot_irqs_disabled;
 466
 467/* Values used for system_state */
 468extern enum system_states {
 469        SYSTEM_BOOTING,
 470        SYSTEM_RUNNING,
 471        SYSTEM_HALT,
 472        SYSTEM_POWER_OFF,
 473        SYSTEM_RESTART,
 474} system_state;
 475
 476#define TAINT_PROPRIETARY_MODULE        0
 477#define TAINT_FORCED_MODULE             1
 478#define TAINT_CPU_OUT_OF_SPEC           2
 479#define TAINT_FORCED_RMMOD              3
 480#define TAINT_MACHINE_CHECK             4
 481#define TAINT_BAD_PAGE                  5
 482#define TAINT_USER                      6
 483#define TAINT_DIE                       7
 484#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 485#define TAINT_WARN                      9
 486#define TAINT_CRAP                      10
 487#define TAINT_FIRMWARE_WORKAROUND       11
 488#define TAINT_OOT_MODULE                12
 489#define TAINT_UNSIGNED_MODULE           13
 490#define TAINT_SOFTLOCKUP                14
 491#define TAINT_LIVEPATCH                 15
 492
 493extern const char hex_asc[];
 494#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 495#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 496
 497static inline char *hex_byte_pack(char *buf, u8 byte)
 498{
 499        *buf++ = hex_asc_hi(byte);
 500        *buf++ = hex_asc_lo(byte);
 501        return buf;
 502}
 503
 504extern const char hex_asc_upper[];
 505#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 506#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 507
 508static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 509{
 510        *buf++ = hex_asc_upper_hi(byte);
 511        *buf++ = hex_asc_upper_lo(byte);
 512        return buf;
 513}
 514
 515extern int hex_to_bin(char ch);
 516extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 517extern char *bin2hex(char *dst, const void *src, size_t count);
 518
 519bool mac_pton(const char *s, u8 *mac);
 520
 521/*
 522 * General tracing related utility functions - trace_printk(),
 523 * tracing_on/tracing_off and tracing_start()/tracing_stop
 524 *
 525 * Use tracing_on/tracing_off when you want to quickly turn on or off
 526 * tracing. It simply enables or disables the recording of the trace events.
 527 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 528 * file, which gives a means for the kernel and userspace to interact.
 529 * Place a tracing_off() in the kernel where you want tracing to end.
 530 * From user space, examine the trace, and then echo 1 > tracing_on
 531 * to continue tracing.
 532 *
 533 * tracing_stop/tracing_start has slightly more overhead. It is used
 534 * by things like suspend to ram where disabling the recording of the
 535 * trace is not enough, but tracing must actually stop because things
 536 * like calling smp_processor_id() may crash the system.
 537 *
 538 * Most likely, you want to use tracing_on/tracing_off.
 539 */
 540
 541enum ftrace_dump_mode {
 542        DUMP_NONE,
 543        DUMP_ALL,
 544        DUMP_ORIG,
 545};
 546
 547#ifdef CONFIG_TRACING
 548void tracing_on(void);
 549void tracing_off(void);
 550int tracing_is_on(void);
 551void tracing_snapshot(void);
 552void tracing_snapshot_alloc(void);
 553
 554extern void tracing_start(void);
 555extern void tracing_stop(void);
 556
 557static inline __printf(1, 2)
 558void ____trace_printk_check_format(const char *fmt, ...)
 559{
 560}
 561#define __trace_printk_check_format(fmt, args...)                       \
 562do {                                                                    \
 563        if (0)                                                          \
 564                ____trace_printk_check_format(fmt, ##args);             \
 565} while (0)
 566
 567/**
 568 * trace_printk - printf formatting in the ftrace buffer
 569 * @fmt: the printf format for printing
 570 *
 571 * Note: __trace_printk is an internal function for trace_printk and
 572 *       the @ip is passed in via the trace_printk macro.
 573 *
 574 * This function allows a kernel developer to debug fast path sections
 575 * that printk is not appropriate for. By scattering in various
 576 * printk like tracing in the code, a developer can quickly see
 577 * where problems are occurring.
 578 *
 579 * This is intended as a debugging tool for the developer only.
 580 * Please refrain from leaving trace_printks scattered around in
 581 * your code. (Extra memory is used for special buffers that are
 582 * allocated when trace_printk() is used)
 583 *
 584 * A little optization trick is done here. If there's only one
 585 * argument, there's no need to scan the string for printf formats.
 586 * The trace_puts() will suffice. But how can we take advantage of
 587 * using trace_puts() when trace_printk() has only one argument?
 588 * By stringifying the args and checking the size we can tell
 589 * whether or not there are args. __stringify((__VA_ARGS__)) will
 590 * turn into "()\0" with a size of 3 when there are no args, anything
 591 * else will be bigger. All we need to do is define a string to this,
 592 * and then take its size and compare to 3. If it's bigger, use
 593 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 594 * let gcc optimize the rest.
 595 */
 596
 597#define trace_printk(fmt, ...)                          \
 598do {                                                    \
 599        char _______STR[] = __stringify((__VA_ARGS__)); \
 600        if (sizeof(_______STR) > 3)                     \
 601                do_trace_printk(fmt, ##__VA_ARGS__);    \
 602        else                                            \
 603                trace_puts(fmt);                        \
 604} while (0)
 605
 606#define do_trace_printk(fmt, args...)                                   \
 607do {                                                                    \
 608        static const char *trace_printk_fmt                             \
 609                __attribute__((section("__trace_printk_fmt"))) =        \
 610                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 611                                                                        \
 612        __trace_printk_check_format(fmt, ##args);                       \
 613                                                                        \
 614        if (__builtin_constant_p(fmt))                                  \
 615                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 616        else                                                            \
 617                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 618} while (0)
 619
 620extern __printf(2, 3)
 621int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 622
 623extern __printf(2, 3)
 624int __trace_printk(unsigned long ip, const char *fmt, ...);
 625
 626/**
 627 * trace_puts - write a string into the ftrace buffer
 628 * @str: the string to record
 629 *
 630 * Note: __trace_bputs is an internal function for trace_puts and
 631 *       the @ip is passed in via the trace_puts macro.
 632 *
 633 * This is similar to trace_printk() but is made for those really fast
 634 * paths that a developer wants the least amount of "Heisenbug" affects,
 635 * where the processing of the print format is still too much.
 636 *
 637 * This function allows a kernel developer to debug fast path sections
 638 * that printk is not appropriate for. By scattering in various
 639 * printk like tracing in the code, a developer can quickly see
 640 * where problems are occurring.
 641 *
 642 * This is intended as a debugging tool for the developer only.
 643 * Please refrain from leaving trace_puts scattered around in
 644 * your code. (Extra memory is used for special buffers that are
 645 * allocated when trace_puts() is used)
 646 *
 647 * Returns: 0 if nothing was written, positive # if string was.
 648 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 649 */
 650
 651#define trace_puts(str) ({                                              \
 652        static const char *trace_printk_fmt                             \
 653                __attribute__((section("__trace_printk_fmt"))) =        \
 654                __builtin_constant_p(str) ? str : NULL;                 \
 655                                                                        \
 656        if (__builtin_constant_p(str))                                  \
 657                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 658        else                                                            \
 659                __trace_puts(_THIS_IP_, str, strlen(str));              \
 660})
 661extern int __trace_bputs(unsigned long ip, const char *str);
 662extern int __trace_puts(unsigned long ip, const char *str, int size);
 663
 664extern void trace_dump_stack(int skip);
 665
 666/*
 667 * The double __builtin_constant_p is because gcc will give us an error
 668 * if we try to allocate the static variable to fmt if it is not a
 669 * constant. Even with the outer if statement.
 670 */
 671#define ftrace_vprintk(fmt, vargs)                                      \
 672do {                                                                    \
 673        if (__builtin_constant_p(fmt)) {                                \
 674                static const char *trace_printk_fmt                     \
 675                  __attribute__((section("__trace_printk_fmt"))) =      \
 676                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 677                                                                        \
 678                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 679        } else                                                          \
 680                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 681} while (0)
 682
 683extern __printf(2, 0) int
 684__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 685
 686extern __printf(2, 0) int
 687__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 688
 689extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 690#else
 691static inline void tracing_start(void) { }
 692static inline void tracing_stop(void) { }
 693static inline void trace_dump_stack(int skip) { }
 694
 695static inline void tracing_on(void) { }
 696static inline void tracing_off(void) { }
 697static inline int tracing_is_on(void) { return 0; }
 698static inline void tracing_snapshot(void) { }
 699static inline void tracing_snapshot_alloc(void) { }
 700
 701static inline __printf(1, 2)
 702int trace_printk(const char *fmt, ...)
 703{
 704        return 0;
 705}
 706static __printf(1, 0) inline int
 707ftrace_vprintk(const char *fmt, va_list ap)
 708{
 709        return 0;
 710}
 711static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 712#endif /* CONFIG_TRACING */
 713
 714/*
 715 * min()/max()/clamp() macros that also do
 716 * strict type-checking.. See the
 717 * "unnecessary" pointer comparison.
 718 */
 719#define min(x, y) ({                            \
 720        typeof(x) _min1 = (x);                  \
 721        typeof(y) _min2 = (y);                  \
 722        (void) (&_min1 == &_min2);              \
 723        _min1 < _min2 ? _min1 : _min2; })
 724
 725#define max(x, y) ({                            \
 726        typeof(x) _max1 = (x);                  \
 727        typeof(y) _max2 = (y);                  \
 728        (void) (&_max1 == &_max2);              \
 729        _max1 > _max2 ? _max1 : _max2; })
 730
 731#define min3(x, y, z) min((typeof(x))min(x, y), z)
 732#define max3(x, y, z) max((typeof(x))max(x, y), z)
 733
 734/**
 735 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 736 * @x: value1
 737 * @y: value2
 738 */
 739#define min_not_zero(x, y) ({                   \
 740        typeof(x) __x = (x);                    \
 741        typeof(y) __y = (y);                    \
 742        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 743
 744/**
 745 * clamp - return a value clamped to a given range with strict typechecking
 746 * @val: current value
 747 * @lo: lowest allowable value
 748 * @hi: highest allowable value
 749 *
 750 * This macro does strict typechecking of lo/hi to make sure they are of the
 751 * same type as val.  See the unnecessary pointer comparisons.
 752 */
 753#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
 754
 755/*
 756 * ..and if you can't take the strict
 757 * types, you can specify one yourself.
 758 *
 759 * Or not use min/max/clamp at all, of course.
 760 */
 761#define min_t(type, x, y) ({                    \
 762        type __min1 = (x);                      \
 763        type __min2 = (y);                      \
 764        __min1 < __min2 ? __min1: __min2; })
 765
 766#define max_t(type, x, y) ({                    \
 767        type __max1 = (x);                      \
 768        type __max2 = (y);                      \
 769        __max1 > __max2 ? __max1: __max2; })
 770
 771/**
 772 * clamp_t - return a value clamped to a given range using a given type
 773 * @type: the type of variable to use
 774 * @val: current value
 775 * @lo: minimum allowable value
 776 * @hi: maximum allowable value
 777 *
 778 * This macro does no typechecking and uses temporary variables of type
 779 * 'type' to make all the comparisons.
 780 */
 781#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
 782
 783/**
 784 * clamp_val - return a value clamped to a given range using val's type
 785 * @val: current value
 786 * @lo: minimum allowable value
 787 * @hi: maximum allowable value
 788 *
 789 * This macro does no typechecking and uses temporary variables of whatever
 790 * type the input argument 'val' is.  This is useful when val is an unsigned
 791 * type and min and max are literals that will otherwise be assigned a signed
 792 * integer type.
 793 */
 794#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 795
 796
 797/*
 798 * swap - swap value of @a and @b
 799 */
 800#define swap(a, b) \
 801        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 802
 803/**
 804 * container_of - cast a member of a structure out to the containing structure
 805 * @ptr:        the pointer to the member.
 806 * @type:       the type of the container struct this is embedded in.
 807 * @member:     the name of the member within the struct.
 808 *
 809 */
 810#define container_of(ptr, type, member) ({                      \
 811        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 812        (type *)( (char *)__mptr - offsetof(type,member) );})
 813
 814/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 815#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 816# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 817#endif
 818
 819/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
 820#define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
 821        (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
 822         BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
 823         /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
 824         BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
 825         BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
 826         /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
 827         BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
 828         /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
 829         BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
 830         (perms))
 831#endif
 832