root/tools/perf/util/perf-hooks.c

DEFINITIONS

1. perf_hooks__invoke
2. perf_hooks__recover
3. perf_hooks__set_hook
4. perf_hooks__get_hook

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * perf_hooks.c
   4  *
   5  * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
   6  * Copyright (C) 2016 Huawei Inc.
   7  */
   8 
   9 #include <errno.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <setjmp.h>
  13 #include <linux/err.h>
  14 #include <linux/kernel.h>
  15 #include "util/debug.h"
  16 #include "util/perf-hooks.h"
  17 
  18 static sigjmp_buf jmpbuf;
  19 static const struct perf_hook_desc *current_perf_hook;
  20 
  21 void perf_hooks__invoke(const struct perf_hook_desc *desc)
  22 {
  23         if (!(desc && desc->p_hook_func && *desc->p_hook_func))
  24                 return;
  25 
  26         if (sigsetjmp(jmpbuf, 1)) {
  27                 pr_warning("Fatal error (SEGFAULT) in perf hook '%s'\n",
  28                            desc->hook_name);
  29                 *(current_perf_hook->p_hook_func) = NULL;
  30         } else {
  31                 current_perf_hook = desc;
  32                 (**desc->p_hook_func)(desc->hook_ctx);
  33         }
  34         current_perf_hook = NULL;
  35 }
  36 
  37 void perf_hooks__recover(void)
  38 {
  39         if (current_perf_hook)
  40                 siglongjmp(jmpbuf, 1);
  41 }
  42 
  43 #define PERF_HOOK(name)                                 \
  44 perf_hook_func_t __perf_hook_func_##name = NULL;        \
  45 struct perf_hook_desc __perf_hook_desc_##name =         \
  46         {.hook_name = #name,                            \
  47          .p_hook_func = &__perf_hook_func_##name,       \
  48          .hook_ctx = NULL};
  49 #include "perf-hooks-list.h"
  50 #undef PERF_HOOK
  51 
  52 #define PERF_HOOK(name)         \
  53         &__perf_hook_desc_##name,
  54 
  55 static struct perf_hook_desc *perf_hooks[] = {
  56 #include "perf-hooks-list.h"
  57 };
  58 #undef PERF_HOOK
  59 
  60 int perf_hooks__set_hook(const char *hook_name,
  61                          perf_hook_func_t hook_func,
  62                          void *hook_ctx)
  63 {
  64         unsigned int i;
  65 
  66         for (i = 0; i < ARRAY_SIZE(perf_hooks); i++) {
  67                 if (strcmp(hook_name, perf_hooks[i]->hook_name) != 0)
  68                         continue;
  69 
  70                 if (*(perf_hooks[i]->p_hook_func))
  71                         pr_warning("Overwrite existing hook: %s\n", hook_name);
  72                 *(perf_hooks[i]->p_hook_func) = hook_func;
  73                 perf_hooks[i]->hook_ctx = hook_ctx;
  74                 return 0;
  75         }
  76         return -ENOENT;
  77 }
  78 
  79 perf_hook_func_t perf_hooks__get_hook(const char *hook_name)
  80 {
  81         unsigned int i;
  82 
  83         for (i = 0; i < ARRAY_SIZE(perf_hooks); i++) {
  84                 if (strcmp(hook_name, perf_hooks[i]->hook_name) != 0)
  85                         continue;
  86 
  87                 return *(perf_hooks[i]->p_hook_func);
  88         }
  89         return ERR_PTR(-ENOENT);
  90 }