[librseq.git] / include / rseq / rseq.h

/* SPDX-License-Identifier: LGPL-2.1-only OR MIT */
/*
 * rseq.h
 *
 * (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#ifndef RSEQ_H
#define RSEQ_H

#include <stdint.h>
#include <stdbool.h>
#include <pthread.h>
#include <signal.h>
#include <sched.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <linux/rseq.h>

/*
 * Empty code injection macros, override when testing.
 * It is important to consider that the ASM injection macros need to be
 * fully reentrant (e.g. do not modify the stack).
 */
#ifndef RSEQ_INJECT_ASM
#define RSEQ_INJECT_ASM(n)
#endif

#ifndef RSEQ_INJECT_C
#define RSEQ_INJECT_C(n)
#endif

#ifndef RSEQ_INJECT_INPUT
#define RSEQ_INJECT_INPUT
#endif

#ifndef RSEQ_INJECT_CLOBBER
#define RSEQ_INJECT_CLOBBER
#endif

#ifndef RSEQ_INJECT_FAILED
#define RSEQ_INJECT_FAILED
#endif

#ifdef __cplusplus
extern "C" {
#endif

extern __thread struct rseq __rseq_abi;

#ifdef __cplusplus
}
#endif

#define rseq_likely(x)		__builtin_expect(!!(x), 1)
#define rseq_unlikely(x)	__builtin_expect(!!(x), 0)
#define rseq_barrier()		__asm__ __volatile__("" : : : "memory")

#define RSEQ_ACCESS_ONCE(x)	(*(__volatile__  __typeof__(x) *)&(x))
#define RSEQ_WRITE_ONCE(x, v)	__extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
#define RSEQ_READ_ONCE(x)	RSEQ_ACCESS_ONCE(x)

#define __rseq_str_1(x)	#x
#define __rseq_str(x)		__rseq_str_1(x)

#define rseq_log(fmt, args...)						       \
	fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
		## args, __func__)

#define rseq_bug(fmt, args...)		\
	do {				\
		rseq_log(fmt, ##args);	\
		abort();		\
	} while (0)

#if defined(__x86_64__) || defined(__i386__)
#include <rseq/rseq-x86.h>
#elif defined(__ARMEL__) || defined(__ARMEB__)
#include <rseq/rseq-arm.h>
#elif defined (__AARCH64EL__)
#include <rseq/rseq-arm64.h>
#elif defined(__PPC__)
#include <rseq/rseq-ppc.h>
#elif defined(__mips__)
#include <rseq/rseq-mips.h>
#elif defined(__s390__)
#include <rseq/rseq-s390.h>
#else
#error unsupported target
#endif

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Register rseq for the current thread. This needs to be called once
 * by any thread which uses restartable sequences, before they start
 * using restartable sequences, to ensure restartable sequences
 * succeed. A restartable sequence executed from a non-registered
 * thread will always fail.
 */
int rseq_register_current_thread(void);

/*
 * Unregister rseq for current thread.
 */
int rseq_unregister_current_thread(void);

/*
 * Restartable sequence fallback for reading the current CPU number.
 */
int32_t rseq_fallback_current_cpu(void);

int rseq_available(void);

/*
 * Values returned can be either the current CPU number, -1 (rseq is
 * uninitialized), or -2 (rseq initialization has failed).
 */
static inline int32_t rseq_current_cpu_raw(void)
{
	return RSEQ_READ_ONCE(__rseq_abi.cpu_id);
}

/*
 * Returns a possible CPU number, which is typically the current CPU.
 * The returned CPU number can be used to prepare for an rseq critical
 * section, which will confirm whether the cpu number is indeed the
 * current one, and whether rseq is initialized.
 *
 * The CPU number returned by rseq_cpu_start should always be validated
 * by passing it to a rseq asm sequence, or by comparing it to the
 * return value of rseq_current_cpu_raw() if the rseq asm sequence
 * does not need to be invoked.
 */
static inline uint32_t rseq_cpu_start(void)
{
	return RSEQ_READ_ONCE(__rseq_abi.cpu_id_start);
}

static inline uint32_t rseq_current_cpu(void)
{
	int32_t cpu;

	cpu = rseq_current_cpu_raw();
	if (rseq_unlikely(cpu < 0))
		cpu = rseq_fallback_current_cpu();
	return cpu;
}

static inline void rseq_clear_rseq_cs(void)
{
#ifdef __LP64__
	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr, 0);
#else
	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr.ptr32, 0);
#endif
}

/*
 * rseq_prepare_unload() should be invoked by each thread executing a rseq
 * critical section at least once between their last critical section and
 * library unload of the library defining the rseq critical section
 * (struct rseq_cs). This also applies to use of rseq in code generated by
 * JIT: rseq_prepare_unload() should be invoked at least once by each
 * thread executing a rseq critical section before reclaim of the memory
 * holding the struct rseq_cs.
 */
static inline void rseq_prepare_unload(void)
{
	rseq_clear_rseq_cs();
}

#ifdef __cplusplus
}
#endif

#endif  /* RSEQ_H_ */
Commit	Line	Data
744d0b8b	1	/* SPDX-License-Identifier: LGPL-2.1-only OR MIT */
784b0012 MD	2	/*
	3	* rseq.h
	4	*
	5	* (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	6	*/
	7
	8	#ifndef RSEQ_H
	9	#define RSEQ_H
	10
	11	#include <stdint.h>
	12	#include <stdbool.h>
	13	#include <pthread.h>
	14	#include <signal.h>
	15	#include <sched.h>
	16	#include <errno.h>
	17	#include <stdio.h>
	18	#include <stdlib.h>
	19	#include <sched.h>
	20	#include <linux/rseq.h>
	21
	22	/*
	23	* Empty code injection macros, override when testing.
	24	* It is important to consider that the ASM injection macros need to be
	25	* fully reentrant (e.g. do not modify the stack).
	26	*/
	27	#ifndef RSEQ_INJECT_ASM
	28	#define RSEQ_INJECT_ASM(n)
	29	#endif
	30
	31	#ifndef RSEQ_INJECT_C
	32	#define RSEQ_INJECT_C(n)
	33	#endif
	34
	35	#ifndef RSEQ_INJECT_INPUT
	36	#define RSEQ_INJECT_INPUT
	37	#endif
	38
	39	#ifndef RSEQ_INJECT_CLOBBER
	40	#define RSEQ_INJECT_CLOBBER
	41	#endif
	42
	43	#ifndef RSEQ_INJECT_FAILED
	44	#define RSEQ_INJECT_FAILED
	45	#endif
	46
15260018	47	#ifdef __cplusplus
60a27517 MG	48	extern "C" {
	49	#endif
	50
78fd8175	51	extern __thread struct rseq __rseq_abi;
784b0012	52
15260018	53	#ifdef __cplusplus
60a27517 MG	54	}
	55	#endif
	56
784b0012 MD	57	#define rseq_likely(x) __builtin_expect(!!(x), 1)
	58	#define rseq_unlikely(x) __builtin_expect(!!(x), 0)
	59	#define rseq_barrier() __asm__ __volatile__("" : : : "memory")
	60
	61	#define RSEQ_ACCESS_ONCE(x) ((__volatile__ __typeof__(x) )&(x))
	62	#define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
	63	#define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
	64
	65	#define __rseq_str_1(x) #x
	66	#define __rseq_str(x) __rseq_str_1(x)
	67
	68	#define rseq_log(fmt, args...) \
	69	fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
	70	## args, __func__)
	71
	72	#define rseq_bug(fmt, args...) \
	73	do { \
	74	rseq_log(fmt, ##args); \
	75	abort(); \
	76	} while (0)
	77
	78	#if defined(__x86_64__) \|\| defined(__i386__)
	79	#include <rseq/rseq-x86.h>
510fdec0	80	#elif defined(__ARMEL__) \|\| defined(__ARMEB__)
784b0012	81	#include <rseq/rseq-arm.h>
d78a16c2 MD	82	#elif defined (__AARCH64EL__)
d78a16c2 MD	83	#include <rseq/rseq-arm64.h>
784b0012 MD	84	#elif defined(__PPC__)
	85	#include <rseq/rseq-ppc.h>
	86	#elif defined(__mips__)
	87	#include <rseq/rseq-mips.h>
4969e3fa MD	88	#elif defined(__s390__)
4969e3fa MD	89	#include <rseq/rseq-s390.h>
784b0012 MD	90	#else
	91	#error unsupported target
	92	#endif
	93
15260018	94	#ifdef __cplusplus
60a27517 MG	95	extern "C" {
	96	#endif
	97
784b0012 MD	98	/*
	99	* Register rseq for the current thread. This needs to be called once
	100	* by any thread which uses restartable sequences, before they start
	101	* using restartable sequences, to ensure restartable sequences
	102	* succeed. A restartable sequence executed from a non-registered
	103	* thread will always fail.
	104	*/
	105	int rseq_register_current_thread(void);
	106
	107	/*
	108	* Unregister rseq for current thread.
	109	*/
	110	int rseq_unregister_current_thread(void);
	111
	112	/*
	113	* Restartable sequence fallback for reading the current CPU number.
	114	*/
	115	int32_t rseq_fallback_current_cpu(void);
	116
52e82b87 MD	117	int rseq_available(void);
52e82b87 MD	118
784b0012 MD	119	/*
	120	* Values returned can be either the current CPU number, -1 (rseq is
	121	* uninitialized), or -2 (rseq initialization has failed).
	122	*/
	123	static inline int32_t rseq_current_cpu_raw(void)
	124	{
78fd8175	125	return RSEQ_READ_ONCE(__rseq_abi.cpu_id);
784b0012 MD	126	}
	127
	128	/*
	129	* Returns a possible CPU number, which is typically the current CPU.
	130	* The returned CPU number can be used to prepare for an rseq critical
	131	* section, which will confirm whether the cpu number is indeed the
	132	* current one, and whether rseq is initialized.
	133	*
	134	* The CPU number returned by rseq_cpu_start should always be validated
	135	* by passing it to a rseq asm sequence, or by comparing it to the
	136	* return value of rseq_current_cpu_raw() if the rseq asm sequence
	137	* does not need to be invoked.
	138	*/
	139	static inline uint32_t rseq_cpu_start(void)
	140	{
78fd8175	141	return RSEQ_READ_ONCE(__rseq_abi.cpu_id_start);
784b0012 MD	142	}
	143
	144	static inline uint32_t rseq_current_cpu(void)
	145	{
	146	int32_t cpu;
	147
	148	cpu = rseq_current_cpu_raw();
	149	if (rseq_unlikely(cpu < 0))
	150	cpu = rseq_fallback_current_cpu();
	151	return cpu;
	152	}
	153
	154	static inline void rseq_clear_rseq_cs(void)
	155	{
	156	#ifdef __LP64__
78fd8175	157	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr, 0);
784b0012	158	#else
78fd8175	159	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr.ptr32, 0);
784b0012 MD	160	#endif
	161	}
	162
	163	/*
	164	* rseq_prepare_unload() should be invoked by each thread executing a rseq
	165	* critical section at least once between their last critical section and
	166	* library unload of the library defining the rseq critical section
	167	* (struct rseq_cs). This also applies to use of rseq in code generated by
	168	* JIT: rseq_prepare_unload() should be invoked at least once by each
	169	* thread executing a rseq critical section before reclaim of the memory
	170	* holding the struct rseq_cs.
	171	*/
	172	static inline void rseq_prepare_unload(void)
	173	{
	174	rseq_clear_rseq_cs();
	175	}
	176
15260018	177	#ifdef __cplusplus
60a27517 MG	178	}
	179	#endif
	180
784b0012	181	#endif /* RSEQ_H_ */