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 
perf_hooks__invoke(const struct perf_hook_desc * desc)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 
perf_hooks__recover(void)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 
perf_hooks__set_hook(const char * hook_name,perf_hook_func_t hook_func,void * hook_ctx)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 
perf_hooks__get_hook(const char * hook_name)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 }
91