perf-hooks.c

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// 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 <setjmp.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include "util/util.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);
}