[PATCH 06/10] perf probe: Check if dwarf_getlocations() is available

From: Arnaldo Carvalho de Melo
Date: Thu May 12 2016 - 16:06:35 EST


From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

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@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Vinson Lee <vlee@xxxxxxxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-9l7luqkq4gfnx7vrklkq4obs@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/build/Makefile.feature | 2 ++
tools/build/feature/Makefile | 4 ++++
tools/build/feature/test-all.c | 5 +++++
tools/build/feature/test-dwarf_getlocations.c | 12 ++++++++++++
tools/perf/config/Makefile | 6 ++++++
tools/perf/util/dwarf-aux.c | 9 +++++++++
6 files changed, 38 insertions(+)
create mode 100644 tools/build/feature/test-dwarf_getlocations.c

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
--
2.5.5