perf tools: Add feature detection for gelf_getnote()

That is not present on some libelf implementations, such as the one used
in Alpine Linux: libelf-0.8.13.

This ends up disabling the SDT code, that relies on this function.

One alternative would be to provide an weak fallback implementation or
the open coded variant used by the buildid sysfs notes reading code.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-82lh22ybedy9b9lych8xj12g@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 17 insertions, 0 deletions

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 3dd529bb0604..fe12bee57418 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -40,6 +40,7 @@ FEATURE_TESTS_BASIC :=			\
         libbfd                          \
         libelf                          \
         libelf-getphdrnum               \
+        libelf-gelf_getnote             \
         libelf-getshdrstrndx            \
         libelf-mmap                     \
         libnuma                         \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 674711629ef0..d6017c1abdb0 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -17,6 +17,7 @@ FILES=					\
         test-cplus-demangle.bin         \
         test-libelf.bin                 \
         test-libelf-getphdrnum.bin      \
+        test-libelf-gelf_getnote.bin    \
         test-libelf-getshdrstrndx.bin   \
         test-libelf-mmap.bin            \
         test-libnuma.bin                \
@@ -99,6 +100,9 @@ $(OUTPUT)test-libelf-mmap.bin:
 $(OUTPUT)test-libelf-getphdrnum.bin:
         $(BUILD) -lelf
 
+$(OUTPUT)test-libelf-gelf_getnote.bin:
+        $(BUILD) -lelf
+
 $(OUTPUT)test-libelf-getshdrstrndx.bin:
         $(BUILD) -lelf
 
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index 7433cca33306..843aed024a3a 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -49,6 +49,10 @@
 # include "test-libelf-getphdrnum.c"
 #undef main
 
+#define main main_test_libelf_gelf_getnote
+# include "test-libelf-gelf_getnote.c"
+#undef main
+
 #define main main_test_libelf_getshdrstrndx
 # include "test-libelf-getshdrstrndx.c"
 #undef main
@@ -153,6 +157,7 @@ int main(int argc, char *argv[])
         main_test_dwarf();
         main_test_dwarf_getlocations();
         main_test_libelf_getphdrnum();
+        main_test_libelf_gelf_getnote();
         main_test_libelf_getshdrstrndx();
         main_test_libunwind();
         main_test_libaudit();
diff --git a/tools/build/feature/test-libelf-gelf_getnote.c b/tools/build/feature/test-libelf-gelf_getnote.c
new file mode 100644
index 000000000000..d78cf4d5271f
--- /dev/null
+++ b/tools/build/feature/test-libelf-gelf_getnote.c
@@ -0,0 +1,7 @@
+#include <stdlib.h>
+#include <gelf.h>
+
+int main(void)
+{
+        return gelf_getnote(NULL, 0, NULL, NULL, NULL);
+}