[PATCH v4 18/18] perf clang jit: Export getpid() to perf hook

[Wang Nan]

After this patch perf hooks can retrive pid of perf itself by calling
getpid. It is important for excluding event from perf.

This commit is also an example to show how to export more helpers to
hooked script.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/util/c++/bpf-helper-str.c | 1 +
 tools/perf/util/c++/clang.cpp        | 1 +
 2 files changed, 2 insertions(+)

diff --git a/tools/perf/util/c++/bpf-helper-str.c b/tools/perf/util/c++/bpf-helper-str.c
index f4d6d57..1ad6ec0 100644
--- a/tools/perf/util/c++/bpf-helper-str.c
+++ b/tools/perf/util/c++/bpf-helper-str.c
@@ -12,6 +12,7 @@ const char clang_builtin_bpf_helper_str[] =
 "#define SEC(NAME) __attribute__((section(NAME), used))\n"
 "extern int printf(const char *, ...);\n"
 "extern int puts(const char *);\n"
+"extern int getpid(void);\n"
 "extern int perf_map_update_elem(void *, void *, void *, void *, unsigned long);\n"
 "extern int perf_map_lookup_elem(void *, void *, void *, void *);\n"
 "extern int perf_map_get_next_key(void *, void *, void *, void *);\n"
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index d49305a..ca5264c 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -239,6 +239,7 @@ static std::map<const std::string, const void *> exported_funcs =
 	EXPORT(test__clang_callback),
 	EXPORT(printf),
 	EXPORT(puts),
+	EXPORT(getpid),
 	EXPORT(JIT_HELPER_FUNC_NAME(map_update_elem)),
 	EXPORT(JIT_HELPER_FUNC_NAME(map_lookup_elem)),
 	EXPORT(JIT_HELPER_FUNC_NAME(map_get_next_key)),
-- 
2.10.1