[v3,04/30] perf tools: Introduce perf hooks

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 67d2a90..fa26865 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -37,6 +37,7 @@ 
 #include "util/llvm-utils.h"
 #include "util/bpf-loader.h"
 #include "util/trigger.h"
+#include "util/perf-hooks.h"
 #include "asm/bug.h"
 
 #include <unistd.h>
@@ -206,6 +207,12 @@  static void sig_handler(int sig)
 	done = 1;
 }
 
+static void sigsegv_handler(int sig)
+{
+	perf_hooks__recover();
+	sighandler_dump_stack(sig);
+}
+
 static void record__sig_exit(void)
 {
 	if (signr == -1)
@@ -833,6 +840,7 @@  static int __cmd_record(struct record *rec, int argc, const char **argv)
 	signal(SIGCHLD, sig_handler);
 	signal(SIGINT, sig_handler);
 	signal(SIGTERM, sig_handler);
+	signal(SIGSEGV, sigsegv_handler);
 
 	if (rec->opts.auxtrace_snapshot_mode || rec->switch_output) {
 		signal(SIGUSR2, snapshot_sig_handler);
@@ -970,6 +978,7 @@  static int __cmd_record(struct record *rec, int argc, const char **argv)
 
 	trigger_ready(&auxtrace_snapshot_trigger);
 	trigger_ready(&switch_output_trigger);
+	perf_hooks__invoke_record_start();
 	for (;;) {
 		unsigned long long hits = rec->samples;
 
@@ -1114,6 +1123,8 @@  static int __cmd_record(struct record *rec, int argc, const char **argv)
 		}
 	}
 
+	perf_hooks__invoke_record_end();
+
 	if (!err && !quiet) {
 		char samples[128];
 		const char *postfix = rec->timestamp_filename ?
diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 8a4ce49..af3ec94 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -42,6 +42,7 @@  perf-y += backward-ring-buffer.o
 perf-y += sdt.o
 perf-y += is_printable_array.o
 perf-y += bitmap.o
+perf-y += perf-hooks.o
 
 $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
 	$(call rule_mkdir)
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 778668a..dab83f7 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -230,6 +230,10 @@  static struct test generic_tests[] = {
 		.func = test__bitmap_print,
 	},
 	{
+		.desc = "Test perf hooks",
+		.func = test__perf_hooks,
+	},
+	{
 		.func = NULL,
 	},
 };
diff --git a/tools/perf/tests/perf-hooks.c b/tools/perf/tests/perf-hooks.c
new file mode 100644
index 0000000..9338cb2
--- /dev/null
+++ b/tools/perf/tests/perf-hooks.c
@@ -0,0 +1,44 @@ 
+#include <signal.h>
+#include <stdlib.h>
+
+#include "tests.h"
+#include "debug.h"
+#include "util.h"
+#include "perf-hooks.h"
+
+static void sigsegv_handler(int sig __maybe_unused)
+{
+	pr_debug("SIGSEGV is observed as expected, try to recover.\n");
+	perf_hooks__recover();
+	signal(SIGSEGV, SIG_DFL);
+	raise(SIGSEGV);
+	exit(-1);
+}
+
+static int hook_flags;
+
+static void the_hook(void)
+{
+	int *p = NULL;
+
+	hook_flags = 1234;
+
+	/* Generate a segfault, test perf_hooks__recover */
+	*p = 0;
+}
+
+int test__perf_hooks(int subtest __maybe_unused)
+{
+	signal(SIGSEGV, sigsegv_handler);
+	perf_hooks__set_hook("test", the_hook);
+	perf_hooks__invoke_test();
+
+	/* hook is triggered? */
+	if (hook_flags != 1234)
+		return TEST_FAIL;
+
+	/* the buggy hook is removed? */
+	if (perf_hooks__get_hook("test"))
+		return TEST_FAIL;
+	return TEST_OK;
+}
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index 7c196c5..3a1f98f 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -91,6 +91,7 @@  int test__cpu_map_print(int subtest);
 int test__sdt_event(int subtest);
 int test__is_printable_array(int subtest);
 int test__bitmap_print(int subtest);
+int test__perf_hooks(int subtest);
 
 #if defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 1dc67ef..b2a47aa 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -123,6 +123,8 @@  libperf-$(CONFIG_LIBELF) += genelf.o
 libperf-$(CONFIG_DWARF) += genelf_debug.o
 endif
 
+libperf-y += perf-hooks.o
+
 CFLAGS_config.o   += -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
 # avoid compiler warnings in 32-bit mode
 CFLAGS_genelf_debug.o  += -Wno-packed
diff --git a/tools/perf/util/perf-hooks-list.h b/tools/perf/util/perf-hooks-list.h
new file mode 100644
index 0000000..2867c07
--- /dev/null
+++ b/tools/perf/util/perf-hooks-list.h
@@ -0,0 +1,3 @@ 
+PERF_HOOK(record_start)
+PERF_HOOK(record_end)
+PERF_HOOK(test)
diff --git a/tools/perf/util/perf-hooks.c b/tools/perf/util/perf-hooks.c
new file mode 100644
index 0000000..4ce88e3
--- /dev/null
+++ b/tools/perf/util/perf-hooks.c
@@ -0,0 +1,84 @@ 
+/*
+ * 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 "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)();
+	}
+	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};
+#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)
+{
+	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;
+		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);
+}
diff --git a/tools/perf/util/perf-hooks.h b/tools/perf/util/perf-hooks.h
new file mode 100644
index 0000000..1d482b2
--- /dev/null
+++ b/tools/perf/util/perf-hooks.h
@@ -0,0 +1,37 @@ 
+#ifndef PERF_UTIL_PERF_HOOKS_H
+#define PERF_UTIL_PERF_HOOKS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void (*perf_hook_func_t)(void);
+struct perf_hook_desc {
+	const char * const hook_name;
+	perf_hook_func_t * const p_hook_func;
+};
+
+extern void perf_hooks__invoke(const struct perf_hook_desc *);
+extern void perf_hooks__recover(void);
+
+#define PERF_HOOK(name)					\
+extern struct perf_hook_desc __perf_hook_desc_##name;	\
+static inline void perf_hooks__invoke_##name(void)	\
+{ 							\
+	perf_hooks__invoke(&__perf_hook_desc_##name);	\
+}
+
+#include "perf-hooks-list.h"
+#undef PERF_HOOK
+
+extern int
+perf_hooks__set_hook(const char *hook_name,
+		     perf_hook_func_t hook_func);
+
+extern perf_hook_func_t
+perf_hooks__get_hook(const char *hook_name);
+
+#ifdef __cplusplus
+}
+#endif
+#endif