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))
 247void might_fault(void);
 248#else
 249static inline void might_fault(void) { }
 250#endif
 251
 252extern struct atomic_notifier_head panic_notifier_list;
 253extern long (*panic_blink)(int state);
 254__printf(1, 2)
 255void panic(const char *fmt, ...)
 256        __noreturn __cold;
 257extern void oops_enter(void);
 258extern void oops_exit(void);
 259void print_oops_end_marker(void);
 260extern int oops_may_print(void);
 261void do_exit(long error_code)
 262        __noreturn;
 263void complete_and_exit(struct completion *, long)
 264        __noreturn;
 265
 266/* Internal, do not use. */
 267int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 268int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 269
 270int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 271int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 272
 273/**
 274 * kstrtoul - convert a string to an unsigned long
 275 * @s: The start of the string. The string must be null-terminated, and may also
 276 *  include a single newline before its terminating null. The first character
 277 *  may also be a plus sign, but not a minus sign.
 278 * @base: The number base to use. The maximum supported base is 16. If base is
 279 *  given as 0, then the base of the string is automatically detected with the
 280 *  conventional semantics - If it begins with 0x the number will be parsed as a
 281 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 282 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 283 * @res: Where to write the result of the conversion on success.
 284 *
 285 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 286 * Used as a replacement for the obsolete simple_strtoull. Return code must
 287 * be checked.
 288*/
 289static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 290{
 291        /*
 292         * We want to shortcut function call, but
 293         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 294         */
 295        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 296            __alignof__(unsigned long) == __alignof__(unsigned long long))
 297                return kstrtoull(s, base, (unsigned long long *)res);
 298        else
 299                return _kstrtoul(s, base, res);
 300}
 301
 302/**
 303 * kstrtol - convert a string to a long
 304 * @s: The start of the string. The string must be null-terminated, and may also
 305 *  include a single newline before its terminating null. The first character
 306 *  may also be a plus sign or a minus sign.
 307 * @base: The number base to use. The maximum supported base is 16. If base is
 308 *  given as 0, then the base of the string is automatically detected with the
 309 *  conventional semantics - If it begins with 0x the number will be parsed as a
 310 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 311 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 312 * @res: Where to write the result of the conversion on success.
 313 *
 314 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 315 * Used as a replacement for the obsolete simple_strtoull. Return code must
 316 * be checked.
 317 */
 318static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 319{
 320        /*
 321         * We want to shortcut function call, but
 322         * __builtin_types_compatible_p(long, long long) = 0.
 323         */
 324        if (sizeof(long) == sizeof(long long) &&
 325            __alignof__(long) == __alignof__(long long))
 326                return kstrtoll(s, base, (long long *)res);
 327        else
 328                return _kstrtol(s, base, res);
 329}
 330
 331int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 332int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 333
 334static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 335{
 336        return kstrtoull(s, base, res);
 337}
 338
 339static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 340{
 341        return kstrtoll(s, base, res);
 342}
 343
 344static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 345{
 346        return kstrtouint(s, base, res);
 347}
 348
 349static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 350{
 351        return kstrtoint(s, base, res);
 352}
 353
 354int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 355int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 356int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 357int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 358
 359int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 360int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 361int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 362int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 363int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 364int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 365int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 366int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 367int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 368int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 369
 370static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 371{
 372        return kstrtoull_from_user(s, count, base, res);
 373}
 374
 375static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 376{
 377        return kstrtoll_from_user(s, count, base, res);
 378}
 379
 380static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 381{
 382        return kstrtouint_from_user(s, count, base, res);
 383}
 384
 385static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 386{
 387        return kstrtoint_from_user(s, count, base, res);
 388}
 389
 390/* Obsolete, do not use.  Use kstrto<foo> instead */
 391
 392extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 393extern long simple_strtol(const char *,char **,unsigned int);
 394extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 395extern long long simple_strtoll(const char *,char **,unsigned int);
 396
 397extern int num_to_str(char *buf, int size, unsigned long long num);
 398
 399/* lib/printf utilities */
 400
 401extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 402extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 403extern __printf(3, 4)
 404int snprintf(char *buf, size_t size, const char *fmt, ...);
 405extern __printf(3, 0)
 406int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 407extern __printf(3, 4)
 408int scnprintf(char *buf, size_t size, const char *fmt, ...);
 409extern __printf(3, 0)
 410int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 411extern __printf(2, 3)
 412char *kasprintf(gfp_t gfp, const char *fmt, ...);
 413extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 414
 415extern __scanf(2, 3)
 416int sscanf(const char *, const char *, ...);
 417extern __scanf(2, 0)
 418int vsscanf(const char *, const char *, va_list);
 419
 420extern int get_option(char **str, int *pint);
 421extern char *get_options(const char *str, int nints, int *ints);
 422extern unsigned long long memparse(const char *ptr, char **retptr);
 423extern bool parse_option_str(const char *str, const char *option);
 424
 425extern int core_kernel_text(unsigned long addr);
 426extern int core_kernel_data(unsigned long addr);
 427extern int __kernel_text_address(unsigned long addr);
 428extern int kernel_text_address(unsigned long addr);
 429extern int func_ptr_is_kernel_text(void *ptr);
 430
 431unsigned long int_sqrt(unsigned long);
 432
 433extern void bust_spinlocks(int yes);
 434extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 435extern int panic_timeout;
 436extern int panic_on_oops;
 437extern int panic_on_unrecovered_nmi;
 438extern int panic_on_io_nmi;
 439extern int panic_on_warn;
 440extern int sysctl_panic_on_stackoverflow;
 441/*
 442 * Only to be used by arch init code. If the user over-wrote the default
 443 * CONFIG_PANIC_TIMEOUT, honor it.
 444 */
 445static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 446{
 447        if (panic_timeout == arch_default_timeout)
 448                panic_timeout = timeout;
 449}
 450extern const char *print_tainted(void);
 451enum lockdep_ok {
 452        LOCKDEP_STILL_OK,
 453        LOCKDEP_NOW_UNRELIABLE
 454};
 455extern void add_taint(unsigned flag, enum lockdep_ok);
 456extern int test_taint(unsigned flag);
 457extern unsigned long get_taint(void);
 458extern int root_mountflags;
 459
 460extern bool early_boot_irqs_disabled;
 461
 462/* Values used for system_state */
 463extern enum system_states {
 464        SYSTEM_BOOTING,
 465        SYSTEM_RUNNING,
 466        SYSTEM_HALT,
 467        SYSTEM_POWER_OFF,
 468        SYSTEM_RESTART,
 469} system_state;
 470
 471#define TAINT_PROPRIETARY_MODULE        0
 472#define TAINT_FORCED_MODULE             1
 473#define TAINT_CPU_OUT_OF_SPEC           2
 474#define TAINT_FORCED_RMMOD              3
 475#define TAINT_MACHINE_CHECK             4
 476#define TAINT_BAD_PAGE                  5
 477#define TAINT_USER                      6
 478#define TAINT_DIE                       7
 479#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 480#define TAINT_WARN                      9
 481#define TAINT_CRAP                      10
 482#define TAINT_FIRMWARE_WORKAROUND       11
 483#define TAINT_OOT_MODULE                12
 484#define TAINT_UNSIGNED_MODULE           13
 485#define TAINT_SOFTLOCKUP                14
 486#define TAINT_LIVEPATCH                 15
 487
 488extern const char hex_asc[];
 489#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 490#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 491
 492static inline char *hex_byte_pack(char *buf, u8 byte)
 493{
 494        *buf++ = hex_asc_hi(byte);
 495        *buf++ = hex_asc_lo(byte);
 496        return buf;
 497}
 498
 499extern const char hex_asc_upper[];
 500#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
 501#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
 502
 503static inline char *hex_byte_pack_upper(char *buf, u8 byte)
 504{
 505        *buf++ = hex_asc_upper_hi(byte);
 506        *buf++ = hex_asc_upper_lo(byte);
 507        return buf;
 508}
 509
 510extern int hex_to_bin(char ch);
 511extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 512extern char *bin2hex(char *dst, const void *src, size_t count);
 513
 514bool mac_pton(const char *s, u8 *mac);
 515
 516/*
 517 * General tracing related utility functions - trace_printk(),
 518 * tracing_on/tracing_off and tracing_start()/tracing_stop
 519 *
 520 * Use tracing_on/tracing_off when you want to quickly turn on or off
 521 * tracing. It simply enables or disables the recording of the trace events.
 522 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 523 * file, which gives a means for the kernel and userspace to interact.
 524 * Place a tracing_off() in the kernel where you want tracing to end.
 525 * From user space, examine the trace, and then echo 1 > tracing_on
 526 * to continue tracing.
 527 *
 528 * tracing_stop/tracing_start has slightly more overhead. It is used
 529 * by things like suspend to ram where disabling the recording of the
 530 * trace is not enough, but tracing must actually stop because things
 531 * like calling smp_processor_id() may crash the system.
 532 *
 533 * Most likely, you want to use tracing_on/tracing_off.
 534 */
 535#ifdef CONFIG_RING_BUFFER
 536/* trace_off_permanent stops recording with no way to bring it back */
 537void tracing_off_permanent(void);
 538#else
 539static inline void tracing_off_permanent(void) { }
 540#endif
 541
 542enum ftrace_dump_mode {
 543        DUMP_NONE,
 544        DUMP_ALL,
 545        DUMP_ORIG,
 546};
 547
 548#ifdef CONFIG_TRACING
 549void tracing_on(void);
 550void tracing_off(void);
 551int tracing_is_on(void);
 552void tracing_snapshot(void);
 553void tracing_snapshot_alloc(void);
 554
 555extern void tracing_start(void);
 556extern void tracing_stop(void);
 557
 558static inline __printf(1, 2)
 559void ____trace_printk_check_format(const char *fmt, ...)
 560{
 561}
 562#define __trace_printk_check_format(fmt, args...)                       \
 563do {                                                                    \
 564        if (0)                                                          \
 565                ____trace_printk_check_format(fmt, ##args);             \
 566} while (0)
 567
 568/**
 569 * trace_printk - printf formatting in the ftrace buffer
 570 * @fmt: the printf format for printing
 571 *
 572 * Note: __trace_printk is an internal function for trace_printk and
 573 *       the @ip is passed in via the trace_printk macro.
 574 *
 575 * This function allows a kernel developer to debug fast path sections
 576 * that printk is not appropriate for. By scattering in various
 577 * printk like tracing in the code, a developer can quickly see
 578 * where problems are occurring.
 579 *
 580 * This is intended as a debugging tool for the developer only.
 581 * Please refrain from leaving trace_printks scattered around in
 582 * your code. (Extra memory is used for special buffers that are
 583 * allocated when trace_printk() is used)
 584 *
 585 * A little optization trick is done here. If there's only one
 586 * argument, there's no need to scan the string for printf formats.
 587 * The trace_puts() will suffice. But how can we take advantage of
 588 * using trace_puts() when trace_printk() has only one argument?
 589 * By stringifying the args and checking the size we can tell
 590 * whether or not there are args. __stringify((__VA_ARGS__)) will
 591 * turn into "()\0" with a size of 3 when there are no args, anything
 592 * else will be bigger. All we need to do is define a string to this,
 593 * and then take its size and compare to 3. If it's bigger, use
 594 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 595 * let gcc optimize the rest.
 596 */
 597
 598#define trace_printk(fmt, ...)                          \
 599do {                                                    \
 600        char _______STR[] = __stringify((__VA_ARGS__)); \
 601        if (sizeof(_______STR) > 3)                     \
 602                do_trace_printk(fmt, ##__VA_ARGS__);    \
 603        else                                            \
 604                trace_puts(fmt);                        \
 605} while (0)
 606
 607#define do_trace_printk(fmt, args...)                                   \
 608do {                                                                    \
 609        static const char *trace_printk_fmt                             \
 610                __attribute__((section("__trace_printk_fmt"))) =        \
 611                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 612                                                                        \
 613        __trace_printk_check_format(fmt, ##args);                       \
 614                                                                        \
 615        if (__builtin_constant_p(fmt))                                  \
 616                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 617        else                                                            \
 618                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 619} while (0)
 620
 621extern __printf(2, 3)
 622int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 623
 624extern __printf(2, 3)
 625int __trace_printk(unsigned long ip, const char *fmt, ...);
 626
 627/**
 628 * trace_puts - write a string into the ftrace buffer
 629 * @str: the string to record
 630 *
 631 * Note: __trace_bputs is an internal function for trace_puts and
 632 *       the @ip is passed in via the trace_puts macro.
 633 *
 634 * This is similar to trace_printk() but is made for those really fast
 635 * paths that a developer wants the least amount of "Heisenbug" affects,
 636 * where the processing of the print format is still too much.
 637 *
 638 * This function allows a kernel developer to debug fast path sections
 639 * that printk is not appropriate for. By scattering in various
 640 * printk like tracing in the code, a developer can quickly see
 641 * where problems are occurring.
 642 *
 643 * This is intended as a debugging tool for the developer only.
 644 * Please refrain from leaving trace_puts scattered around in
 645 * your code. (Extra memory is used for special buffers that are
 646 * allocated when trace_puts() is used)
 647 *
 648 * Returns: 0 if nothing was written, positive # if string was.
 649 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 650 */
 651
 652#define trace_puts(str) ({                                              \
 653        static const char *trace_printk_fmt                             \
 654                __attribute__((section("__trace_printk_fmt"))) =        \
 655                __builtin_constant_p(str) ? str : NULL;                 \
 656                                                                        \
 657        if (__builtin_constant_p(str))                                  \
 658                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
 659        else                                                            \
 660                __trace_puts(_THIS_IP_, str, strlen(str));              \
 661})
 662extern int __trace_bputs(unsigned long ip, const char *str);
 663extern int __trace_puts(unsigned long ip, const char *str, int size);
 664
 665extern void trace_dump_stack(int skip);
 666
 667/*
 668 * The double __builtin_constant_p is because gcc will give us an error
 669 * if we try to allocate the static variable to fmt if it is not a
 670 * constant. Even with the outer if statement.
 671 */
 672#define ftrace_vprintk(fmt, vargs)                                      \
 673do {                                                                    \
 674        if (__builtin_constant_p(fmt)) {                                \
 675                static const char *trace_printk_fmt                     \
 676                  __attribute__((section("__trace_printk_fmt"))) =      \
 677                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 678                                                                        \
 679                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 680        } else                                                          \
 681                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 682} while (0)
 683
 684extern int
 685__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 686
 687extern int
 688__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 689
 690extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 691#else
 692static inline void tracing_start(void) { }
 693static inline void tracing_stop(void) { }
 694static inline void trace_dump_stack(int skip) { }
 695
 696static inline void tracing_on(void) { }
 697static inline void tracing_off(void) { }
 698static inline int tracing_is_on(void) { return 0; }
 699static inline void tracing_snapshot(void) { }
 700static inline void tracing_snapshot_alloc(void) { }
 701
 702static inline __printf(1, 2)
 703int trace_printk(const char *fmt, ...)
 704{
 705        return 0;
 706}
 707static inline int
 708ftrace_vprintk(const char *fmt, va_list ap)
 709{
 710        return 0;
 711}
 712static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 713#endif /* CONFIG_TRACING */
 714
 715/*
 716 * min()/max()/clamp() macros that also do
 717 * strict type-checking.. See the
 718 * "unnecessary" pointer comparison.
 719 */
 720#define min(x, y) ({                            \
 721        typeof(x) _min1 = (x);                  \
 722        typeof(y) _min2 = (y);                  \
 723        (void) (&_min1 == &_min2);              \
 724        _min1 < _min2 ? _min1 : _min2; })
 725
 726#define max(x, y) ({                            \
 727        typeof(x) _max1 = (x);                  \
 728        typeof(y) _max2 = (y);                  \
 729        (void) (&_max1 == &_max2);              \
 730        _max1 > _max2 ? _max1 : _max2; })
 731
 732#define min3(x, y, z) min((typeof(x))min(x, y), z)
 733#define max3(x, y, z) max((typeof(x))max(x, y), z)
 734
 735/**
 736 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 737 * @x: value1
 738 * @y: value2
 739 */
 740#define min_not_zero(x, y) ({                   \
 741        typeof(x) __x = (x);                    \
 742        typeof(y) __y = (y);                    \
 743        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 744
 745/**
 746 * clamp - return a value clamped to a given range with strict typechecking
 747 * @val: current value
 748 * @lo: lowest allowable value
 749 * @hi: highest allowable value
 750 *
 751 * This macro does strict typechecking of lo/hi to make sure they are of the
 752 * same type as val.  See the unnecessary pointer comparisons.
 753 */
 754#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
 755
 756/*
 757 * ..and if you can't take the strict
 758 * types, you can specify one yourself.
 759 *
 760 * Or not use min/max/clamp at all, of course.
 761 */
 762#define min_t(type, x, y) ({                    \
 763        type __min1 = (x);                      \
 764        type __min2 = (y);                      \
 765        __min1 < __min2 ? __min1: __min2; })
 766
 767#define max_t(type, x, y) ({                    \
 768        type __max1 = (x);                      \
 769        type __max2 = (y);                      \
 770        __max1 > __max2 ? __max1: __max2; })
 771
 772/**
 773 * clamp_t - return a value clamped to a given range using a given type
 774 * @type: the type of variable to use
 775 * @val: current value
 776 * @lo: minimum allowable value
 777 * @hi: maximum allowable value
 778 *
 779 * This macro does no typechecking and uses temporary variables of type
 780 * 'type' to make all the comparisons.
 781 */
 782#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
 783
 784/**
 785 * clamp_val - return a value clamped to a given range using val's type
 786 * @val: current value
 787 * @lo: minimum allowable value
 788 * @hi: maximum allowable value
 789 *
 790 * This macro does no typechecking and uses temporary variables of whatever
 791 * type the input argument 'val' is.  This is useful when val is an unsigned
 792 * type and min and max are literals that will otherwise be assigned a signed
 793 * integer type.
 794 */
 795#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 796
 797
 798/*
 799 * swap - swap value of @a and @b
 800 */
 801#define swap(a, b) \
 802        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 803
 804/**
 805 * container_of - cast a member of a structure out to the containing structure
 806 * @ptr:        the pointer to the member.
 807 * @type:       the type of the container struct this is embedded in.
 808 * @member:     the name of the member within the struct.
 809 *
 810 */
 811#define container_of(ptr, type, member) ({                      \
 812        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 813        (type *)( (char *)__mptr - offsetof(type,member) );})
 814
 815/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 816#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 817# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 818#endif
 819
 820/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
 821#define VERIFY_OCTAL_PERMISSIONS(perms)                                 \
 822        (BUILD_BUG_ON_ZERO((perms) < 0) +                               \
 823         BUILD_BUG_ON_ZERO((perms) > 0777) +                            \
 824         /* User perms >= group perms >= other perms */                 \
 825         BUILD_BUG_ON_ZERO(((perms) >> 6) < (((perms) >> 3) & 7)) +     \
 826         BUILD_BUG_ON_ZERO((((perms) >> 3) & 7) < ((perms) & 7)) +      \
 827         /* Other writable?  Generally considered a bad idea. */        \
 828         BUILD_BUG_ON_ZERO((perms) & 2) +                               \
 829         (perms))
 830#endif
 831