// SPDX-License-Identifier: GPL-2.0
/*
 * perf_hooks.c
 *
 * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
 * Copyright (C) 2016 Huawei Inc.
 */

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <setjmp.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include "util/debug.h"
#include "util/perf-hooks.h"

static sigjmp_buf jmpbuf;
static const struct perf_hook_desc *current_perf_hook;

void perf_hooks__invoke(const struct perf_hook_desc *desc)
{
        if (!(desc && desc->p_hook_func && *desc->p_hook_func))
                return;

        if (sigsetjmp(jmpbuf, 1)) {
                pr_warning("Fatal error (SEGFAULT) in perf hook '%s'\n",
                           desc->hook_name);
                *(current_perf_hook->p_hook_func) = NULL;
        } else {
                current_perf_hook = desc;
                (**desc->p_hook_func)(desc->hook_ctx);
        }
        current_perf_hook = NULL;
}

void perf_hooks__recover(void)
{
        if (current_perf_hook)
                siglongjmp(jmpbuf, 1);
}

#define PERF_HOOK(name)                                 \
perf_hook_func_t __perf_hook_func_##name = NULL;        \
struct perf_hook_desc __perf_hook_desc_##name =         \
        {.hook_name = #name,                            \
         .p_hook_func = &__perf_hook_func_##name,       \
         .hook_ctx = NULL};
#include "perf-hooks-list.h"
#undef PERF_HOOK

#define PERF_HOOK(name)         \
        &__perf_hook_desc_##name,

static struct perf_hook_desc *perf_hooks[] = {
#include "perf-hooks-list.h"
};
#undef PERF_HOOK

int perf_hooks__set_hook(const char *hook_name,
                         perf_hook_func_t hook_func,
                         void *hook_ctx)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(perf_hooks); i++) {
                if (strcmp(hook_name, perf_hooks[i]->hook_name) != 0)
                        continue;

                if (*(perf_hooks[i]->p_hook_func))
                        pr_warning("Overwrite existing hook: %s\n", hook_name);
                *(perf_hooks[i]->p_hook_func) = hook_func;
                perf_hooks[i]->hook_ctx = hook_ctx;
                return 0;
        }
        return -ENOENT;
}

perf_hook_func_t perf_hooks__get_hook(const char *hook_name)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(perf_hooks); i++) {
                if (strcmp(hook_name, perf_hooks[i]->hook_name) != 0)
                        continue;

                return *(perf_hooks[i]->p_hook_func);
        }
        return ERR_PTR(-ENOENT);
}