perf probe: Check if dwarf_getlocations() is available

If not, tell the user that:

  config/Makefile:273: Old libdw.h, finding variables at given 'perf probe' point will not work, install elfutils-devel/libdw-dev >= 0.157

And return -ENOTSUPP in die_get_var_range(), failing features that
need it, like the one pointed out above.

This fixes the build on older systems, such as Ubuntu 12.04.5.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Vinson Lee <vlee@freedesktop.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-9l7luqkq4gfnx7vrklkq4obs@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

6 files changed, 38 insertions, 0 deletions

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 6b7707270aa3..9f878619077a 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -30,6 +30,7 @@ endef
 FEATURE_TESTS_BASIC :=                  \
         backtrace                       \
         dwarf                           \
+        dwarf_getlocations              \
         fortify-source                  \
         sync-compare-and-swap           \
         glibc                           \
@@ -78,6 +79,7 @@ endif
 
 FEATURE_DISPLAY ?=                      \
         dwarf                           \
+        dwarf_getlocations              \
         glibc                           \
         gtk2                            \
         libaudit                        \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index c5f4c417428d..4ae94dbfdab9 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -3,6 +3,7 @@ FILES=					\
         test-backtrace.bin              \
         test-bionic.bin                 \
         test-dwarf.bin                  \
+        test-dwarf_getlocations.bin     \
         test-fortify-source.bin         \
         test-sync-compare-and-swap.bin  \
         test-glibc.bin                  \
@@ -82,6 +83,9 @@ endif
 $(OUTPUT)test-dwarf.bin:
         $(BUILD) $(DWARFLIBS)
 
+$(OUTPUT)test-dwarf_getlocations.bin:
+        $(BUILD) $(DWARFLIBS)
+
 $(OUTPUT)test-libelf-mmap.bin:
         $(BUILD) -lelf
 
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index e499a36c1e4a..a282e8cb84f3 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -41,6 +41,10 @@
 # include "test-dwarf.c"
 #undef main
 
+#define main main_test_dwarf_getlocations
+# include "test-dwarf_getlocations.c"
+#undef main
+
 #define main main_test_libelf_getphdrnum
 # include "test-libelf-getphdrnum.c"
 #undef main
@@ -143,6 +147,7 @@ int main(int argc, char *argv[])
         main_test_libelf_mmap();
         main_test_glibc();
         main_test_dwarf();
+        main_test_dwarf_getlocations();
         main_test_libelf_getphdrnum();
         main_test_libunwind();
         main_test_libaudit();
diff --git a/tools/build/feature/test-dwarf_getlocations.c b/tools/build/feature/test-dwarf_getlocations.c
new file mode 100644
index 000000000000..70162699dd43
--- /dev/null
+++ b/tools/build/feature/test-dwarf_getlocations.c
@@ -0,0 +1,12 @@
+#include <stdlib.h>
+#include <elfutils/libdw.h>
+
+int main(void)
+{
+        Dwarf_Addr base, start, end;
+        Dwarf_Attribute attr;
+        Dwarf_Op *op;
+        size_t nops;
+        ptrdiff_t offset = 0;
+        return (int)dwarf_getlocations(&attr, offset, &base, &start, &end, &op, &nops);
+}
diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index f7d7f5a1cad5..6f8f6430f2bf 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -268,6 +268,12 @@ else
     ifneq ($(feature-dwarf), 1)
       msg := $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.138, disables dwarf support. Please install new elfutils-devel/libdw-dev);
       NO_DWARF := 1
+    else
+      ifneq ($(feature-dwarf_getlocations), 1)
+        msg := $(warning Old libdw.h, finding variables at given 'perf probe' point will not work, install elfutils-devel/libdw-dev >= 0.157);
+      else
+        CFLAGS += -DHAVE_DWARF_GETLOCATIONS
+      endif # dwarf_getlocations
     endif # Dwarf support
   endif # libelf support
 endif # NO_LIBELF
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 577e600c8eb1..aea189b41cc8 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -959,6 +959,7 @@ int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
         return 0;
 }
 
+#ifdef HAVE_DWARF_GETLOCATIONS
 /**
  * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
  * @sp_die: a subprogram DIE
@@ -1080,3 +1081,11 @@ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
 
         return ret;
 }
+#else
+int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
+                      Dwarf_Die *vr_die __maybe_unused,
+                      struct strbuf *buf __maybe_unused)
+{
+        return -ENOTSUP;
+}
+#endif