[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

extern __thread struct rseq __rseq_abi;
extern int __rseq_handled;

#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__)
#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

/*
 * 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();
}

#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
78fd8175	47	extern __thread struct rseq __rseq_abi;
17f997bc	48	extern int __rseq_handled;
784b0012 MD	49
	50	#define rseq_likely(x) __builtin_expect(!!(x), 1)
	51	#define rseq_unlikely(x) __builtin_expect(!!(x), 0)
	52	#define rseq_barrier() __asm__ __volatile__("" : : : "memory")
	53
	54	#define RSEQ_ACCESS_ONCE(x) ((__volatile__ __typeof__(x) )&(x))
	55	#define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
	56	#define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
	57
	58	#define __rseq_str_1(x) #x
	59	#define __rseq_str(x) __rseq_str_1(x)
	60
	61	#define rseq_log(fmt, args...) \
	62	fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
	63	## args, __func__)
	64
	65	#define rseq_bug(fmt, args...) \
	66	do { \
	67	rseq_log(fmt, ##args); \
	68	abort(); \
	69	} while (0)
	70
	71	#if defined(__x86_64__) \|\| defined(__i386__)
	72	#include <rseq/rseq-x86.h>
	73	#elif defined(__ARMEL__)
	74	#include <rseq/rseq-arm.h>
d78a16c2 MD	75	#elif defined (__AARCH64EL__)
d78a16c2 MD	76	#include <rseq/rseq-arm64.h>
784b0012 MD	77	#elif defined(__PPC__)
	78	#include <rseq/rseq-ppc.h>
	79	#elif defined(__mips__)
	80	#include <rseq/rseq-mips.h>
4969e3fa MD	81	#elif defined(__s390__)
4969e3fa MD	82	#include <rseq/rseq-s390.h>
784b0012 MD	83	#else
	84	#error unsupported target
	85	#endif
	86
	87	/*
	88	* Register rseq for the current thread. This needs to be called once
	89	* by any thread which uses restartable sequences, before they start
	90	* using restartable sequences, to ensure restartable sequences
	91	* succeed. A restartable sequence executed from a non-registered
	92	* thread will always fail.
	93	*/
	94	int rseq_register_current_thread(void);
	95
	96	/*
	97	* Unregister rseq for current thread.
	98	*/
	99	int rseq_unregister_current_thread(void);
	100
	101	/*
	102	* Restartable sequence fallback for reading the current CPU number.
	103	*/
	104	int32_t rseq_fallback_current_cpu(void);
	105
52e82b87 MD	106	int rseq_available(void);
52e82b87 MD	107
784b0012 MD	108	/*
	109	* Values returned can be either the current CPU number, -1 (rseq is
	110	* uninitialized), or -2 (rseq initialization has failed).
	111	*/
	112	static inline int32_t rseq_current_cpu_raw(void)
	113	{
78fd8175	114	return RSEQ_READ_ONCE(__rseq_abi.cpu_id);
784b0012 MD	115	}
	116
	117	/*
	118	* Returns a possible CPU number, which is typically the current CPU.
	119	* The returned CPU number can be used to prepare for an rseq critical
	120	* section, which will confirm whether the cpu number is indeed the
	121	* current one, and whether rseq is initialized.
	122	*
	123	* The CPU number returned by rseq_cpu_start should always be validated
	124	* by passing it to a rseq asm sequence, or by comparing it to the
	125	* return value of rseq_current_cpu_raw() if the rseq asm sequence
	126	* does not need to be invoked.
	127	*/
	128	static inline uint32_t rseq_cpu_start(void)
	129	{
78fd8175	130	return RSEQ_READ_ONCE(__rseq_abi.cpu_id_start);
784b0012 MD	131	}
	132
	133	static inline uint32_t rseq_current_cpu(void)
	134	{
	135	int32_t cpu;
	136
	137	cpu = rseq_current_cpu_raw();
	138	if (rseq_unlikely(cpu < 0))
	139	cpu = rseq_fallback_current_cpu();
	140	return cpu;
	141	}
	142
	143	static inline void rseq_clear_rseq_cs(void)
	144	{
	145	#ifdef __LP64__
78fd8175	146	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr, 0);
784b0012	147	#else
78fd8175	148	RSEQ_WRITE_ONCE(__rseq_abi.rseq_cs.ptr.ptr32, 0);
784b0012 MD	149	#endif
	150	}
	151
	152	/*
	153	* rseq_prepare_unload() should be invoked by each thread executing a rseq
	154	* critical section at least once between their last critical section and
	155	* library unload of the library defining the rseq critical section
	156	* (struct rseq_cs). This also applies to use of rseq in code generated by
	157	* JIT: rseq_prepare_unload() should be invoked at least once by each
	158	* thread executing a rseq critical section before reclaim of the memory
	159	* holding the struct rseq_cs.
	160	*/
	161	static inline void rseq_prepare_unload(void)
	162	{
	163	rseq_clear_rseq_cs();
	164	}
	165
	166	#endif /* RSEQ_H_ */