Commit f1f13af9 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf callchain: Cache eh/debug frame offset for dwarf unwind 



When libunwind tries to resolve callchains it needs to know the offset
of .eh_frame_hdr or .debug_frame to access the dso.

Since it will always return the same result for a given DSO, just cache
the result as an optimization.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1422518843-25818-41-git-send-email-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 459a3df7

tools/perf/util/dso.h

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ struct dso { 
		u32		 status_seen;

		size_t		 file_size;

		struct list_head open_entry;

		u64		 frame_offset;

	} data;



	union { /* Tool specific area */

tools/perf/util/unwind-libunwind.c

+20 −11
Original line number Diff line number Diff line
@@ -266,14 +266,17 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, 
				     u64 *fde_count)

{

	int ret = -EINVAL, fd;

	u64 offset;

	u64 offset = dso->data.frame_offset;



	if (offset == 0) {

		fd = dso__data_fd(dso, machine);

		if (fd < 0)

			return -EINVAL;



		/* Check the .eh_frame section for unwinding info */

		offset = elf_section_offset(fd, ".eh_frame_hdr");

		dso->data.frame_offset = offset;

	}



	if (offset)

		ret = unwind_spec_ehframe(dso, machine, offset,
@@ -287,14 +290,20 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, 
static int read_unwind_spec_debug_frame(struct dso *dso,

					struct machine *machine, u64 *offset)

{

	int fd = dso__data_fd(dso, machine);

	int fd;

	u64 ofs = dso->data.frame_offset;



	if (ofs == 0) {

		fd = dso__data_fd(dso, machine);

		if (fd < 0)

			return -EINVAL;



		/* Check the .debug_frame section for unwinding info */

	*offset = elf_section_offset(fd, ".debug_frame");

		ofs = elf_section_offset(fd, ".debug_frame");

		dso->data.frame_offset = ofs;

	}



	*offset = ofs;

	if (*offset)

		return 0;

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