[linux-2.6-block.git] / include / uapi / linux / rseq.h

/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_RSEQ_H
#define _UAPI_LINUX_RSEQ_H

/*
 * linux/rseq.h
 *
 * Restartable sequences system call API
 *
 * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/types.h>
#include <asm/byteorder.h>

enum rseq_cpu_id_state {
	RSEQ_CPU_ID_UNINITIALIZED		= -1,
	RSEQ_CPU_ID_REGISTRATION_FAILED		= -2,
};

enum rseq_flags {
	RSEQ_FLAG_UNREGISTER = (1 << 0),
};

enum rseq_cs_flags_bit {
	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT	= 0,
	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT	= 1,
	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT	= 2,
};

enum rseq_cs_flags {
	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT	=
		(1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL	=
		(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE	=
		(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
};

/*
 * struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always
 * contained within a single cache-line. It is usually declared as
 * link-time constant data.
 */
struct rseq_cs {
	/* Version of this structure. */
	__u32 version;
	/* enum rseq_cs_flags */
	__u32 flags;
	__u64 start_ip;
	/* Offset from start_ip. */
	__u64 post_commit_offset;
	__u64 abort_ip;
} __attribute__((aligned(4 * sizeof(__u64))));

/*
 * struct rseq is aligned on 4 * 8 bytes to ensure it is always
 * contained within a single cache-line.
 *
 * A single struct rseq per thread is allowed.
 */
struct rseq {
	/*
	 * Restartable sequences cpu_id_start field. Updated by the
	 * kernel. Read by user-space with single-copy atomicity
	 * semantics. This field should only be read by the thread which
	 * registered this data structure. Aligned on 32-bit. Always
	 * contains a value in the range of possible CPUs, although the
	 * value may not be the actual current CPU (e.g. if rseq is not
	 * initialized). This CPU number value should always be compared
	 * against the value of the cpu_id field before performing a rseq
	 * commit or returning a value read from a data structure indexed
	 * using the cpu_id_start value.
	 */
	__u32 cpu_id_start;
	/*
	 * Restartable sequences cpu_id field. Updated by the kernel.
	 * Read by user-space with single-copy atomicity semantics. This
	 * field should only be read by the thread which registered this
	 * data structure. Aligned on 32-bit. Values
	 * RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
	 * have a special semantic: the former means "rseq uninitialized",
	 * and latter means "rseq initialization failed". This value is
	 * meant to be read within rseq critical sections and compared
	 * with the cpu_id_start value previously read, before performing
	 * the commit instruction, or read and compared with the
	 * cpu_id_start value before returning a value loaded from a data
	 * structure indexed using the cpu_id_start value.
	 */
	__u32 cpu_id;
	/*
	 * Restartable sequences rseq_cs field.
	 *
	 * Contains NULL when no critical section is active for the current
	 * thread, or holds a pointer to the currently active struct rseq_cs.
	 *
	 * Updated by user-space, which sets the address of the currently
	 * active rseq_cs at the beginning of assembly instruction sequence
	 * block, and set to NULL by the kernel when it restarts an assembly
	 * instruction sequence block, as well as when the kernel detects that
	 * it is preempting or delivering a signal outside of the range
	 * targeted by the rseq_cs. Also needs to be set to NULL by user-space
	 * before reclaiming memory that contains the targeted struct rseq_cs.
	 *
	 * Read and set by the kernel. Set by user-space with single-copy
	 * atomicity semantics. This field should only be updated by the
	 * thread which registered this data structure. Aligned on 64-bit.
	 */
	union {
		__u64 ptr64;
#ifdef __LP64__
		__u64 ptr;
#else
		struct {
#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN)
			__u32 padding;		/* Initialized to zero. */
			__u32 ptr32;
#else /* LITTLE */
			__u32 ptr32;
			__u32 padding;		/* Initialized to zero. */
#endif /* ENDIAN */
		} ptr;
#endif
	} rseq_cs;

	/*
	 * Restartable sequences flags field.
	 *
	 * This field should only be updated by the thread which
	 * registered this data structure. Read by the kernel.
	 * Mainly used for single-stepping through rseq critical sections
	 * with debuggers.
	 *
	 * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
	 *     Inhibit instruction sequence block restart on preemption
	 *     for this thread.
	 * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
	 *     Inhibit instruction sequence block restart on signal
	 *     delivery for this thread.
	 * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
	 *     Inhibit instruction sequence block restart on migration for
	 *     this thread.
	 */
	__u32 flags;
} __attribute__((aligned(4 * sizeof(__u64))));

#endif /* _UAPI_LINUX_RSEQ_H */
Commit	Line	Data
d7822b1e MD	1	/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
	2	#ifndef _UAPI_LINUX_RSEQ_H
	3	#define _UAPI_LINUX_RSEQ_H
	4
	5	/*
	6	* linux/rseq.h
	7	*
	8	* Restartable sequences system call API
	9	*
	10	* Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	11	*/
	12
ec9c82e0 MD	13	#include <linux/types.h>
ec9c82e0 MD	14	#include <asm/byteorder.h>
d7822b1e MD	15
	16	enum rseq_cpu_id_state {
	17	RSEQ_CPU_ID_UNINITIALIZED = -1,
	18	RSEQ_CPU_ID_REGISTRATION_FAILED = -2,
	19	};
	20
	21	enum rseq_flags {
	22	RSEQ_FLAG_UNREGISTER = (1 << 0),
	23	};
	24
	25	enum rseq_cs_flags_bit {
	26	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
	27	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
	28	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
	29	};
	30
	31	enum rseq_cs_flags {
	32	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT =
	33	(1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
	34	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL =
	35	(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
	36	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =
	37	(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
	38	};
	39
	40	/*
	41	* struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always
	42	* contained within a single cache-line. It is usually declared as
	43	* link-time constant data.
	44	*/
	45	struct rseq_cs {
	46	/* Version of this structure. */
	47	__u32 version;
	48	/* enum rseq_cs_flags */
	49	__u32 flags;
e96d7135	50	__u64 start_ip;
d7822b1e	51	/* Offset from start_ip. */
e96d7135 MD	52	__u64 post_commit_offset;
e96d7135 MD	53	__u64 abort_ip;
d7822b1e MD	54	} __attribute__((aligned(4 * sizeof(__u64))));
	55
	56	/*
	57	* struct rseq is aligned on 4 * 8 bytes to ensure it is always
	58	* contained within a single cache-line.
	59	*
	60	* A single struct rseq per thread is allowed.
	61	*/
	62	struct rseq {
	63	/*
	64	* Restartable sequences cpu_id_start field. Updated by the
0fb9a1ab MD	65	* kernel. Read by user-space with single-copy atomicity
	66	* semantics. This field should only be read by the thread which
	67	* registered this data structure. Aligned on 32-bit. Always
	68	* contains a value in the range of possible CPUs, although the
	69	* value may not be the actual current CPU (e.g. if rseq is not
	70	* initialized). This CPU number value should always be compared
	71	* against the value of the cpu_id field before performing a rseq
	72	* commit or returning a value read from a data structure indexed
	73	* using the cpu_id_start value.
d7822b1e MD	74	*/
	75	__u32 cpu_id_start;
	76	/*
0fb9a1ab MD	77	* Restartable sequences cpu_id field. Updated by the kernel.
	78	* Read by user-space with single-copy atomicity semantics. This
	79	* field should only be read by the thread which registered this
	80	* data structure. Aligned on 32-bit. Values
	81	* RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
	82	* have a special semantic: the former means "rseq uninitialized",
	83	* and latter means "rseq initialization failed". This value is
	84	* meant to be read within rseq critical sections and compared
	85	* with the cpu_id_start value previously read, before performing
	86	* the commit instruction, or read and compared with the
	87	* cpu_id_start value before returning a value loaded from a data
	88	* structure indexed using the cpu_id_start value.
d7822b1e MD	89	*/
	90	__u32 cpu_id;
	91	/*
	92	* Restartable sequences rseq_cs field.
	93	*
	94	* Contains NULL when no critical section is active for the current
	95	* thread, or holds a pointer to the currently active struct rseq_cs.
	96	*
	97	* Updated by user-space, which sets the address of the currently
	98	* active rseq_cs at the beginning of assembly instruction sequence
	99	* block, and set to NULL by the kernel when it restarts an assembly
	100	* instruction sequence block, as well as when the kernel detects that
	101	* it is preempting or delivering a signal outside of the range
	102	* targeted by the rseq_cs. Also needs to be set to NULL by user-space
	103	* before reclaiming memory that contains the targeted struct rseq_cs.
	104	*
0fb9a1ab MD	105	* Read and set by the kernel. Set by user-space with single-copy
	106	* atomicity semantics. This field should only be updated by the
	107	* thread which registered this data structure. Aligned on 64-bit.
d7822b1e	108	*/
ec9c82e0 MD	109	union {
	110	__u64 ptr64;
	111	#ifdef __LP64__
	112	__u64 ptr;
	113	#else
	114	struct {
	115	#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) \|\| defined(__BIG_ENDIAN)
	116	__u32 padding; /* Initialized to zero. */
	117	__u32 ptr32;
	118	#else /* LITTLE */
	119	__u32 ptr32;
	120	__u32 padding; /* Initialized to zero. */
	121	#endif /* ENDIAN */
	122	} ptr;
	123	#endif
	124	} rseq_cs;
	125
d7822b1e	126	/*
0fb9a1ab MD	127	* Restartable sequences flags field.
	128	*
	129	* This field should only be updated by the thread which
	130	* registered this data structure. Read by the kernel.
	131	* Mainly used for single-stepping through rseq critical sections
	132	* with debuggers.
d7822b1e	133	*
d7822b1e	134	* - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
0fb9a1ab MD	135	* Inhibit instruction sequence block restart on preemption
0fb9a1ab MD	136	* for this thread.
d7822b1e	137	* - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
0fb9a1ab MD	138	* Inhibit instruction sequence block restart on signal
0fb9a1ab MD	139	* delivery for this thread.
d7822b1e	140	* - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
0fb9a1ab MD	141	* Inhibit instruction sequence block restart on migration for
0fb9a1ab MD	142	* this thread.
d7822b1e MD	143	*/
	144	__u32 flags;
	145	} __attribute__((aligned(4 * sizeof(__u64))));
	146
	147	#endif /* _UAPI_LINUX_RSEQ_H */