xref: /linux-6.15/include/linux/kernel.h (revision 6ed7ffdd)
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 STACK_MAGIC	0xdeadbeef
33 
34 #define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
35 
36 #define ALIGN(x, a)		__ALIGN_KERNEL((x), (a))
37 #define __ALIGN_MASK(x, mask)	__ALIGN_KERNEL_MASK((x), (mask))
38 #define PTR_ALIGN(p, a)		((typeof(p))ALIGN((unsigned long)(p), (a)))
39 #define IS_ALIGNED(x, a)		(((x) & ((typeof(x))(a) - 1)) == 0)
40 
41 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
42 
43 /*
44  * This looks more complex than it should be. But we need to
45  * get the type for the ~ right in round_down (it needs to be
46  * as wide as the result!), and we want to evaluate the macro
47  * arguments just once each.
48  */
49 #define __round_mask(x, y) ((__typeof__(x))((y)-1))
50 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
51 #define round_down(x, y) ((x) & ~__round_mask(x, y))
52 
53 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
54 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
55 #define DIV_ROUND_UP_ULL(ll,d) \
56 	({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
57 
58 #if BITS_PER_LONG == 32
59 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
60 #else
61 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
62 #endif
63 
64 /* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
65 #define roundup(x, y) (					\
66 {							\
67 	const typeof(y) __y = y;			\
68 	(((x) + (__y - 1)) / __y) * __y;		\
69 }							\
70 )
71 #define rounddown(x, y) (				\
72 {							\
73 	typeof(x) __x = (x);				\
74 	__x - (__x % (y));				\
75 }							\
76 )
77 
78 /*
79  * Divide positive or negative dividend by positive divisor and round
80  * to closest integer. Result is undefined for negative divisors and
81  * for negative dividends if the divisor variable type is unsigned.
82  */
83 #define DIV_ROUND_CLOSEST(x, divisor)(			\
84 {							\
85 	typeof(x) __x = x;				\
86 	typeof(divisor) __d = divisor;			\
87 	(((typeof(x))-1) > 0 ||				\
88 	 ((typeof(divisor))-1) > 0 || (__x) > 0) ?	\
89 		(((__x) + ((__d) / 2)) / (__d)) :	\
90 		(((__x) - ((__d) / 2)) / (__d));	\
91 }							\
92 )
93 
94 /*
95  * Multiplies an integer by a fraction, while avoiding unnecessary
96  * overflow or loss of precision.
97  */
98 #define mult_frac(x, numer, denom)(			\
99 {							\
100 	typeof(x) quot = (x) / (denom);			\
101 	typeof(x) rem  = (x) % (denom);			\
102 	(quot * (numer)) + ((rem * (numer)) / (denom));	\
103 }							\
104 )
105 
106 
107 #define _RET_IP_		(unsigned long)__builtin_return_address(0)
108 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
109 
110 #ifdef CONFIG_LBDAF
111 # include <asm/div64.h>
112 # define sector_div(a, b) do_div(a, b)
113 #else
114 # define sector_div(n, b)( \
115 { \
116 	int _res; \
117 	_res = (n) % (b); \
118 	(n) /= (b); \
119 	_res; \
120 } \
121 )
122 #endif
123 
124 /**
125  * upper_32_bits - return bits 32-63 of a number
126  * @n: the number we're accessing
127  *
128  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
129  * the "right shift count >= width of type" warning when that quantity is
130  * 32-bits.
131  */
132 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
133 
134 /**
135  * lower_32_bits - return bits 0-31 of a number
136  * @n: the number we're accessing
137  */
138 #define lower_32_bits(n) ((u32)(n))
139 
140 struct completion;
141 struct pt_regs;
142 struct user;
143 
144 #ifdef CONFIG_PREEMPT_VOLUNTARY
145 extern int _cond_resched(void);
146 # define might_resched() _cond_resched()
147 #else
148 # define might_resched() do { } while (0)
149 #endif
150 
151 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
152   void __might_sleep(const char *file, int line, int preempt_offset);
153 /**
154  * might_sleep - annotation for functions that can sleep
155  *
156  * this macro will print a stack trace if it is executed in an atomic
157  * context (spinlock, irq-handler, ...).
158  *
159  * This is a useful debugging help to be able to catch problems early and not
160  * be bitten later when the calling function happens to sleep when it is not
161  * supposed to.
162  */
163 # define might_sleep() \
164 	do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
165 #else
166   static inline void __might_sleep(const char *file, int line,
167 				   int preempt_offset) { }
168 # define might_sleep() do { might_resched(); } while (0)
169 #endif
170 
171 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
172 
173 /*
174  * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
175  * input types abs() returns a signed long.
176  * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
177  * for those.
178  */
179 #define abs(x) ({						\
180 		long ret;					\
181 		if (sizeof(x) == sizeof(long)) {		\
182 			long __x = (x);				\
183 			ret = (__x < 0) ? -__x : __x;		\
184 		} else {					\
185 			int __x = (x);				\
186 			ret = (__x < 0) ? -__x : __x;		\
187 		}						\
188 		ret;						\
189 	})
190 
191 #define abs64(x) ({				\
192 		s64 __x = (x);			\
193 		(__x < 0) ? -__x : __x;		\
194 	})
195 
196 #ifdef CONFIG_PROVE_LOCKING
197 void might_fault(void);
198 #else
199 static inline void might_fault(void)
200 {
201 	might_sleep();
202 }
203 #endif
204 
205 extern struct atomic_notifier_head panic_notifier_list;
206 extern long (*panic_blink)(int state);
207 __printf(1, 2)
208 void panic(const char *fmt, ...)
209 	__noreturn __cold;
210 extern void oops_enter(void);
211 extern void oops_exit(void);
212 void print_oops_end_marker(void);
213 extern int oops_may_print(void);
214 void do_exit(long error_code)
215 	__noreturn;
216 void complete_and_exit(struct completion *, long)
217 	__noreturn;
218 
219 /* Internal, do not use. */
220 int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
221 int __must_check _kstrtol(const char *s, unsigned int base, long *res);
222 
223 int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
224 int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
225 
226 /**
227  * kstrtoul - convert a string to an unsigned long
228  * @s: The start of the string. The string must be null-terminated, and may also
229  *  include a single newline before its terminating null. The first character
230  *  may also be a plus sign, but not a minus sign.
231  * @base: The number base to use. The maximum supported base is 16. If base is
232  *  given as 0, then the base of the string is automatically detected with the
233  *  conventional semantics - If it begins with 0x the number will be parsed as a
234  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
235  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
236  * @res: Where to write the result of the conversion on success.
237  *
238  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
239  * Used as a replacement for the obsolete simple_strtoull. Return code must
240  * be checked.
241 */
242 static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
243 {
244 	/*
245 	 * We want to shortcut function call, but
246 	 * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
247 	 */
248 	if (sizeof(unsigned long) == sizeof(unsigned long long) &&
249 	    __alignof__(unsigned long) == __alignof__(unsigned long long))
250 		return kstrtoull(s, base, (unsigned long long *)res);
251 	else
252 		return _kstrtoul(s, base, res);
253 }
254 
255 /**
256  * kstrtol - convert a string to a long
257  * @s: The start of the string. The string must be null-terminated, and may also
258  *  include a single newline before its terminating null. The first character
259  *  may also be a plus sign or a minus sign.
260  * @base: The number base to use. The maximum supported base is 16. If base is
261  *  given as 0, then the base of the string is automatically detected with the
262  *  conventional semantics - If it begins with 0x the number will be parsed as a
263  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
264  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
265  * @res: Where to write the result of the conversion on success.
266  *
267  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
268  * Used as a replacement for the obsolete simple_strtoull. Return code must
269  * be checked.
270  */
271 static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
272 {
273 	/*
274 	 * We want to shortcut function call, but
275 	 * __builtin_types_compatible_p(long, long long) = 0.
276 	 */
277 	if (sizeof(long) == sizeof(long long) &&
278 	    __alignof__(long) == __alignof__(long long))
279 		return kstrtoll(s, base, (long long *)res);
280 	else
281 		return _kstrtol(s, base, res);
282 }
283 
284 int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
285 int __must_check kstrtoint(const char *s, unsigned int base, int *res);
286 
287 static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
288 {
289 	return kstrtoull(s, base, res);
290 }
291 
292 static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
293 {
294 	return kstrtoll(s, base, res);
295 }
296 
297 static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
298 {
299 	return kstrtouint(s, base, res);
300 }
301 
302 static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
303 {
304 	return kstrtoint(s, base, res);
305 }
306 
307 int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
308 int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
309 int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
310 int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
311 
312 int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
313 int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
314 int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
315 int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
316 int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
317 int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
318 int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
319 int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
320 int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
321 int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
322 
323 static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
324 {
325 	return kstrtoull_from_user(s, count, base, res);
326 }
327 
328 static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
329 {
330 	return kstrtoll_from_user(s, count, base, res);
331 }
332 
333 static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
334 {
335 	return kstrtouint_from_user(s, count, base, res);
336 }
337 
338 static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
339 {
340 	return kstrtoint_from_user(s, count, base, res);
341 }
342 
343 /* Obsolete, do not use.  Use kstrto<foo> instead */
344 
345 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
346 extern long simple_strtol(const char *,char **,unsigned int);
347 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
348 extern long long simple_strtoll(const char *,char **,unsigned int);
349 #define strict_strtoul	kstrtoul
350 #define strict_strtol	kstrtol
351 #define strict_strtoull	kstrtoull
352 #define strict_strtoll	kstrtoll
353 
354 extern int num_to_str(char *buf, int size, unsigned long long num);
355 
356 /* lib/printf utilities */
357 
358 extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
359 extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
360 extern __printf(3, 4)
361 int snprintf(char *buf, size_t size, const char *fmt, ...);
362 extern __printf(3, 0)
363 int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
364 extern __printf(3, 4)
365 int scnprintf(char *buf, size_t size, const char *fmt, ...);
366 extern __printf(3, 0)
367 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
368 extern __printf(2, 3)
369 char *kasprintf(gfp_t gfp, const char *fmt, ...);
370 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
371 
372 extern __scanf(2, 3)
373 int sscanf(const char *, const char *, ...);
374 extern __scanf(2, 0)
375 int vsscanf(const char *, const char *, va_list);
376 
377 extern int get_option(char **str, int *pint);
378 extern char *get_options(const char *str, int nints, int *ints);
379 extern unsigned long long memparse(const char *ptr, char **retptr);
380 
381 extern int core_kernel_text(unsigned long addr);
382 extern int core_kernel_data(unsigned long addr);
383 extern int __kernel_text_address(unsigned long addr);
384 extern int kernel_text_address(unsigned long addr);
385 extern int func_ptr_is_kernel_text(void *ptr);
386 
387 struct pid;
388 extern struct pid *session_of_pgrp(struct pid *pgrp);
389 
390 unsigned long int_sqrt(unsigned long);
391 
392 extern void bust_spinlocks(int yes);
393 extern void wake_up_klogd(void);
394 extern int oops_in_progress;		/* If set, an oops, panic(), BUG() or die() is in progress */
395 extern int panic_timeout;
396 extern int panic_on_oops;
397 extern int panic_on_unrecovered_nmi;
398 extern int panic_on_io_nmi;
399 extern int sysctl_panic_on_stackoverflow;
400 extern const char *print_tainted(void);
401 enum lockdep_ok {
402 	LOCKDEP_STILL_OK,
403 	LOCKDEP_NOW_UNRELIABLE
404 };
405 extern void add_taint(unsigned flag, enum lockdep_ok);
406 extern int test_taint(unsigned flag);
407 extern unsigned long get_taint(void);
408 extern int root_mountflags;
409 
410 extern bool early_boot_irqs_disabled;
411 
412 /* Values used for system_state */
413 extern enum system_states {
414 	SYSTEM_BOOTING,
415 	SYSTEM_RUNNING,
416 	SYSTEM_HALT,
417 	SYSTEM_POWER_OFF,
418 	SYSTEM_RESTART,
419 } system_state;
420 
421 #define TAINT_PROPRIETARY_MODULE	0
422 #define TAINT_FORCED_MODULE		1
423 #define TAINT_UNSAFE_SMP		2
424 #define TAINT_FORCED_RMMOD		3
425 #define TAINT_MACHINE_CHECK		4
426 #define TAINT_BAD_PAGE			5
427 #define TAINT_USER			6
428 #define TAINT_DIE			7
429 #define TAINT_OVERRIDDEN_ACPI_TABLE	8
430 #define TAINT_WARN			9
431 #define TAINT_CRAP			10
432 #define TAINT_FIRMWARE_WORKAROUND	11
433 #define TAINT_OOT_MODULE		12
434 
435 extern const char hex_asc[];
436 #define hex_asc_lo(x)	hex_asc[((x) & 0x0f)]
437 #define hex_asc_hi(x)	hex_asc[((x) & 0xf0) >> 4]
438 
439 static inline char *hex_byte_pack(char *buf, u8 byte)
440 {
441 	*buf++ = hex_asc_hi(byte);
442 	*buf++ = hex_asc_lo(byte);
443 	return buf;
444 }
445 
446 static inline char * __deprecated pack_hex_byte(char *buf, u8 byte)
447 {
448 	return hex_byte_pack(buf, byte);
449 }
450 
451 extern int hex_to_bin(char ch);
452 extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
453 
454 /*
455  * General tracing related utility functions - trace_printk(),
456  * tracing_on/tracing_off and tracing_start()/tracing_stop
457  *
458  * Use tracing_on/tracing_off when you want to quickly turn on or off
459  * tracing. It simply enables or disables the recording of the trace events.
460  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
461  * file, which gives a means for the kernel and userspace to interact.
462  * Place a tracing_off() in the kernel where you want tracing to end.
463  * From user space, examine the trace, and then echo 1 > tracing_on
464  * to continue tracing.
465  *
466  * tracing_stop/tracing_start has slightly more overhead. It is used
467  * by things like suspend to ram where disabling the recording of the
468  * trace is not enough, but tracing must actually stop because things
469  * like calling smp_processor_id() may crash the system.
470  *
471  * Most likely, you want to use tracing_on/tracing_off.
472  */
473 #ifdef CONFIG_RING_BUFFER
474 /* trace_off_permanent stops recording with no way to bring it back */
475 void tracing_off_permanent(void);
476 #else
477 static inline void tracing_off_permanent(void) { }
478 #endif
479 
480 enum ftrace_dump_mode {
481 	DUMP_NONE,
482 	DUMP_ALL,
483 	DUMP_ORIG,
484 };
485 
486 #ifdef CONFIG_TRACING
487 void tracing_on(void);
488 void tracing_off(void);
489 int tracing_is_on(void);
490 
491 extern void tracing_start(void);
492 extern void tracing_stop(void);
493 extern void ftrace_off_permanent(void);
494 
495 static inline __printf(1, 2)
496 void ____trace_printk_check_format(const char *fmt, ...)
497 {
498 }
499 #define __trace_printk_check_format(fmt, args...)			\
500 do {									\
501 	if (0)								\
502 		____trace_printk_check_format(fmt, ##args);		\
503 } while (0)
504 
505 /**
506  * trace_printk - printf formatting in the ftrace buffer
507  * @fmt: the printf format for printing
508  *
509  * Note: __trace_printk is an internal function for trace_printk and
510  *       the @ip is passed in via the trace_printk macro.
511  *
512  * This function allows a kernel developer to debug fast path sections
513  * that printk is not appropriate for. By scattering in various
514  * printk like tracing in the code, a developer can quickly see
515  * where problems are occurring.
516  *
517  * This is intended as a debugging tool for the developer only.
518  * Please refrain from leaving trace_printks scattered around in
519  * your code.
520  */
521 
522 #define trace_printk(fmt, args...)					\
523 do {									\
524 	static const char *trace_printk_fmt				\
525 		__attribute__((section("__trace_printk_fmt"))) =	\
526 		__builtin_constant_p(fmt) ? fmt : NULL;			\
527 									\
528 	__trace_printk_check_format(fmt, ##args);			\
529 									\
530 	if (__builtin_constant_p(fmt))					\
531 		__trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);	\
532 	else								\
533 		__trace_printk(_THIS_IP_, fmt, ##args);			\
534 } while (0)
535 
536 extern __printf(2, 3)
537 int __trace_bprintk(unsigned long ip, const char *fmt, ...);
538 
539 extern __printf(2, 3)
540 int __trace_printk(unsigned long ip, const char *fmt, ...);
541 
542 extern void trace_dump_stack(void);
543 
544 /*
545  * The double __builtin_constant_p is because gcc will give us an error
546  * if we try to allocate the static variable to fmt if it is not a
547  * constant. Even with the outer if statement.
548  */
549 #define ftrace_vprintk(fmt, vargs)					\
550 do {									\
551 	if (__builtin_constant_p(fmt)) {				\
552 		static const char *trace_printk_fmt			\
553 		  __attribute__((section("__trace_printk_fmt"))) =	\
554 			__builtin_constant_p(fmt) ? fmt : NULL;		\
555 									\
556 		__ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);	\
557 	} else								\
558 		__ftrace_vprintk(_THIS_IP_, fmt, vargs);		\
559 } while (0)
560 
561 extern int
562 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
563 
564 extern int
565 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
566 
567 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
568 #else
569 static inline void tracing_start(void) { }
570 static inline void tracing_stop(void) { }
571 static inline void ftrace_off_permanent(void) { }
572 static inline void trace_dump_stack(void) { }
573 
574 static inline void tracing_on(void) { }
575 static inline void tracing_off(void) { }
576 static inline int tracing_is_on(void) { return 0; }
577 
578 static inline __printf(1, 2)
579 int trace_printk(const char *fmt, ...)
580 {
581 	return 0;
582 }
583 static inline int
584 ftrace_vprintk(const char *fmt, va_list ap)
585 {
586 	return 0;
587 }
588 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
589 #endif /* CONFIG_TRACING */
590 
591 /*
592  * min()/max()/clamp() macros that also do
593  * strict type-checking.. See the
594  * "unnecessary" pointer comparison.
595  */
596 #define min(x, y) ({				\
597 	typeof(x) _min1 = (x);			\
598 	typeof(y) _min2 = (y);			\
599 	(void) (&_min1 == &_min2);		\
600 	_min1 < _min2 ? _min1 : _min2; })
601 
602 #define max(x, y) ({				\
603 	typeof(x) _max1 = (x);			\
604 	typeof(y) _max2 = (y);			\
605 	(void) (&_max1 == &_max2);		\
606 	_max1 > _max2 ? _max1 : _max2; })
607 
608 #define min3(x, y, z) ({			\
609 	typeof(x) _min1 = (x);			\
610 	typeof(y) _min2 = (y);			\
611 	typeof(z) _min3 = (z);			\
612 	(void) (&_min1 == &_min2);		\
613 	(void) (&_min1 == &_min3);		\
614 	_min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
615 		(_min2 < _min3 ? _min2 : _min3); })
616 
617 #define max3(x, y, z) ({			\
618 	typeof(x) _max1 = (x);			\
619 	typeof(y) _max2 = (y);			\
620 	typeof(z) _max3 = (z);			\
621 	(void) (&_max1 == &_max2);		\
622 	(void) (&_max1 == &_max3);		\
623 	_max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
624 		(_max2 > _max3 ? _max2 : _max3); })
625 
626 /**
627  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
628  * @x: value1
629  * @y: value2
630  */
631 #define min_not_zero(x, y) ({			\
632 	typeof(x) __x = (x);			\
633 	typeof(y) __y = (y);			\
634 	__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
635 
636 /**
637  * clamp - return a value clamped to a given range with strict typechecking
638  * @val: current value
639  * @min: minimum allowable value
640  * @max: maximum allowable value
641  *
642  * This macro does strict typechecking of min/max to make sure they are of the
643  * same type as val.  See the unnecessary pointer comparisons.
644  */
645 #define clamp(val, min, max) ({			\
646 	typeof(val) __val = (val);		\
647 	typeof(min) __min = (min);		\
648 	typeof(max) __max = (max);		\
649 	(void) (&__val == &__min);		\
650 	(void) (&__val == &__max);		\
651 	__val = __val < __min ? __min: __val;	\
652 	__val > __max ? __max: __val; })
653 
654 /*
655  * ..and if you can't take the strict
656  * types, you can specify one yourself.
657  *
658  * Or not use min/max/clamp at all, of course.
659  */
660 #define min_t(type, x, y) ({			\
661 	type __min1 = (x);			\
662 	type __min2 = (y);			\
663 	__min1 < __min2 ? __min1: __min2; })
664 
665 #define max_t(type, x, y) ({			\
666 	type __max1 = (x);			\
667 	type __max2 = (y);			\
668 	__max1 > __max2 ? __max1: __max2; })
669 
670 /**
671  * clamp_t - return a value clamped to a given range using a given type
672  * @type: the type of variable to use
673  * @val: current value
674  * @min: minimum allowable value
675  * @max: maximum allowable value
676  *
677  * This macro does no typechecking and uses temporary variables of type
678  * 'type' to make all the comparisons.
679  */
680 #define clamp_t(type, val, min, max) ({		\
681 	type __val = (val);			\
682 	type __min = (min);			\
683 	type __max = (max);			\
684 	__val = __val < __min ? __min: __val;	\
685 	__val > __max ? __max: __val; })
686 
687 /**
688  * clamp_val - return a value clamped to a given range using val's type
689  * @val: current value
690  * @min: minimum allowable value
691  * @max: maximum allowable value
692  *
693  * This macro does no typechecking and uses temporary variables of whatever
694  * type the input argument 'val' is.  This is useful when val is an unsigned
695  * type and min and max are literals that will otherwise be assigned a signed
696  * integer type.
697  */
698 #define clamp_val(val, min, max) ({		\
699 	typeof(val) __val = (val);		\
700 	typeof(val) __min = (min);		\
701 	typeof(val) __max = (max);		\
702 	__val = __val < __min ? __min: __val;	\
703 	__val > __max ? __max: __val; })
704 
705 
706 /*
707  * swap - swap value of @a and @b
708  */
709 #define swap(a, b) \
710 	do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
711 
712 /**
713  * container_of - cast a member of a structure out to the containing structure
714  * @ptr:	the pointer to the member.
715  * @type:	the type of the container struct this is embedded in.
716  * @member:	the name of the member within the struct.
717  *
718  */
719 #define container_of(ptr, type, member) ({			\
720 	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
721 	(type *)( (char *)__mptr - offsetof(type,member) );})
722 
723 /* Trap pasters of __FUNCTION__ at compile-time */
724 #define __FUNCTION__ (__func__)
725 
726 /* This helps us to avoid #ifdef CONFIG_SYMBOL_PREFIX */
727 #ifdef CONFIG_SYMBOL_PREFIX
728 #define SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
729 #else
730 #define SYMBOL_PREFIX ""
731 #endif
732 
733 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
734 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
735 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
736 #endif
737 
738 extern int do_sysinfo(struct sysinfo *info);
739 
740 #endif
741