/* SPDX-License-Identifier: LGPL-2.1 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 <stddef.h>
#include "rseq-abi.h"
#include "compiler.h"

#ifndef rseq_sizeof_field
#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
#endif

#ifndef rseq_offsetofend
#define rseq_offsetofend(TYPE, MEMBER) \
        (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER))
#endif

/*
 * 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

#include "rseq-thread-pointer.h"

/* Offset from the thread pointer to the rseq area. */
extern ptrdiff_t rseq_offset;

/*
 * The rseq ABI is composed of extensible feature fields. The extensions
 * are done by appending additional fields at the end of the structure.
 * The rseq_size defines the size of the active feature set which can be
 * used by the application for the current rseq registration. Features
 * starting at offset >= rseq_size are inactive and should not be used.
 *
 * The rseq_size is the intersection between the available allocation
 * size for the rseq area and the feature size supported by the kernel.
 * unsuccessful.
 */
extern unsigned int rseq_size;

/* Flags used during rseq registration. */
extern unsigned int rseq_flags;

enum rseq_mo {
        RSEQ_MO_RELAXED = 0,
        RSEQ_MO_CONSUME = 1,    /* Unused */
        RSEQ_MO_ACQUIRE = 2,    /* Unused */
        RSEQ_MO_RELEASE = 3,
        RSEQ_MO_ACQ_REL = 4,    /* Unused */
        RSEQ_MO_SEQ_CST = 5,    /* Unused */
};

enum rseq_percpu_mode {
        RSEQ_PERCPU_CPU_ID = 0,
        RSEQ_PERCPU_MM_CID = 1,
};

static inline struct rseq_abi *rseq_get_abi(void)
{
        return (struct rseq_abi *) ((uintptr_t) rseq_thread_pointer() + rseq_offset);
}

#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-x86.h>
#elif defined(__ARMEL__)
#include <rseq-arm.h>
#elif defined (__AARCH64EL__)
#include <rseq-arm64.h>
#elif defined(__PPC__)
#include <rseq-ppc.h>
#elif defined(__mips__)
#include <rseq-mips.h>
#elif defined(__s390__)
#include <rseq-s390.h>
#elif defined(__riscv)
#include <rseq-riscv.h>
#elif defined(__or1k__)
#include <rseq-or1k.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);

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

/*
 * Returns true if rseq is supported.
 */
bool 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_ACCESS_ONCE(rseq_get_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_ACCESS_ONCE(rseq_get_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 bool rseq_node_id_available(void)
{
        return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id);
}

/*
 * Current NUMA node number.
 */
static inline uint32_t rseq_current_node_id(void)
{
        assert(rseq_node_id_available());
        return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id);
}

static inline bool rseq_mm_cid_available(void)
{
        return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, mm_cid);
}

static inline uint32_t rseq_current_mm_cid(void)
{
        return RSEQ_ACCESS_ONCE(rseq_get_abi()->mm_cid);
}

static inline void rseq_clear_rseq_cs(void)
{
        RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);
}

/*
 * 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) or the code referred to by the struct rseq_cs start_ip and
 * post_commit_offset fields. 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 or reclaim of the code pointed to by struct
 * rseq_cs start_ip and post_commit_offset fields.
 */
static inline void rseq_prepare_unload(void)
{
        rseq_clear_rseq_cs();
}

static inline __attribute__((always_inline))
int rseq_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                       intptr_t *v, intptr_t expect,
                       intptr_t newv, int cpu)
{
        if (rseq_mo != RSEQ_MO_RELAXED)
                return -1;
        switch (percpu_mode) {
        case RSEQ_PERCPU_CPU_ID:
                return rseq_cmpeqv_storev_relaxed_cpu_id(v, expect, newv, cpu);
        case RSEQ_PERCPU_MM_CID:
                return rseq_cmpeqv_storev_relaxed_mm_cid(v, expect, newv, cpu);
        }
        return -1;
}

/*
 * Compare @v against @expectnot. When it does _not_ match, load @v
 * into @load, and store the content of *@v + voffp into @v.
 */
static inline __attribute__((always_inline))
int rseq_cmpnev_storeoffp_load(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                               intptr_t *v, intptr_t expectnot, long voffp, intptr_t *load,
                               int cpu)
{
        if (rseq_mo != RSEQ_MO_RELAXED)
                return -1;
        switch (percpu_mode) {
        case RSEQ_PERCPU_CPU_ID:
                return rseq_cmpnev_storeoffp_load_relaxed_cpu_id(v, expectnot, voffp, load, cpu);
        case RSEQ_PERCPU_MM_CID:
                return rseq_cmpnev_storeoffp_load_relaxed_mm_cid(v, expectnot, voffp, load, cpu);
        }
        return -1;
}

static inline __attribute__((always_inline))
int rseq_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
              intptr_t *v, intptr_t count, int cpu)
{
        if (rseq_mo != RSEQ_MO_RELAXED)
                return -1;
        switch (percpu_mode) {
        case RSEQ_PERCPU_CPU_ID:
                return rseq_addv_relaxed_cpu_id(v, count, cpu);
        case RSEQ_PERCPU_MM_CID:
                return rseq_addv_relaxed_mm_cid(v, count, cpu);
        }
        return -1;
}

#ifdef RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV
/*
 *   pval = *(ptr+off)
 *  *pval += inc;
 */
static inline __attribute__((always_inline))
int rseq_offset_deref_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                           intptr_t *ptr, long off, intptr_t inc, int cpu)
{
        if (rseq_mo != RSEQ_MO_RELAXED)
                return -1;
        switch (percpu_mode) {
        case RSEQ_PERCPU_CPU_ID:
                return rseq_offset_deref_addv_relaxed_cpu_id(ptr, off, inc, cpu);
        case RSEQ_PERCPU_MM_CID:
                return rseq_offset_deref_addv_relaxed_mm_cid(ptr, off, inc, cpu);
        }
        return -1;
}
#endif

static inline __attribute__((always_inline))
int rseq_cmpeqv_trystorev_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                                 intptr_t *v, intptr_t expect,
                                 intptr_t *v2, intptr_t newv2,
                                 intptr_t newv, int cpu)
{
        switch (rseq_mo) {
        case RSEQ_MO_RELAXED:
                switch (percpu_mode) {
                case RSEQ_PERCPU_CPU_ID:
                        return rseq_cmpeqv_trystorev_storev_relaxed_cpu_id(v, expect, v2, newv2, newv, cpu);
                case RSEQ_PERCPU_MM_CID:
                        return rseq_cmpeqv_trystorev_storev_relaxed_mm_cid(v, expect, v2, newv2, newv, cpu);
                }
                return -1;
        case RSEQ_MO_RELEASE:
                switch (percpu_mode) {
                case RSEQ_PERCPU_CPU_ID:
                        return rseq_cmpeqv_trystorev_storev_release_cpu_id(v, expect, v2, newv2, newv, cpu);
                case RSEQ_PERCPU_MM_CID:
                        return rseq_cmpeqv_trystorev_storev_release_mm_cid(v, expect, v2, newv2, newv, cpu);
                }
                return -1;
        default:
                return -1;
        }
}

static inline __attribute__((always_inline))
int rseq_cmpeqv_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                              intptr_t *v, intptr_t expect,
                              intptr_t *v2, intptr_t expect2,
                              intptr_t newv, int cpu)
{
        if (rseq_mo != RSEQ_MO_RELAXED)
                return -1;
        switch (percpu_mode) {
        case RSEQ_PERCPU_CPU_ID:
                return rseq_cmpeqv_cmpeqv_storev_relaxed_cpu_id(v, expect, v2, expect2, newv, cpu);
        case RSEQ_PERCPU_MM_CID:
                return rseq_cmpeqv_cmpeqv_storev_relaxed_mm_cid(v, expect, v2, expect2, newv, cpu);
        }
        return -1;
}

static inline __attribute__((always_inline))
int rseq_cmpeqv_trymemcpy_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode,
                                 intptr_t *v, intptr_t expect,
                                 void *dst, void *src, size_t len,
                                 intptr_t newv, int cpu)
{
        switch (rseq_mo) {
        case RSEQ_MO_RELAXED:
                switch (percpu_mode) {
                case RSEQ_PERCPU_CPU_ID:
                        return rseq_cmpeqv_trymemcpy_storev_relaxed_cpu_id(v, expect, dst, src, len, newv, cpu);
                case RSEQ_PERCPU_MM_CID:
                        return rseq_cmpeqv_trymemcpy_storev_relaxed_mm_cid(v, expect, dst, src, len, newv, cpu);
                }
                return -1;
        case RSEQ_MO_RELEASE:
                switch (percpu_mode) {
                case RSEQ_PERCPU_CPU_ID:
                        return rseq_cmpeqv_trymemcpy_storev_release_cpu_id(v, expect, dst, src, len, newv, cpu);
                case RSEQ_PERCPU_MM_CID:
                        return rseq_cmpeqv_trymemcpy_storev_release_mm_cid(v, expect, dst, src, len, newv, cpu);
                }
                return -1;
        default:
                return -1;
        }
}

#endif  /* RSEQ_H_ */