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

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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: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
This commit is contained in:
Namhyung Kim 2015-01-29 17:07:21 +09:00 • committed by Arnaldo Carvalho de Melo
commit f1f13af99a
2 changed files with 21 additions and 11 deletions
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1
tools/perf/util/dso.h
View file

@ -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 */

31
tools/perf/util/unwind-libunwind.c
View file

@ -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;
fd = dso__data_fd(dso, machine);
if (fd < 0)
return -EINVAL;
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");
/* 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 (fd < 0)
return -EINVAL;
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");
/* Check the .debug_frame section for unwinding info */
ofs = elf_section_offset(fd, ".debug_frame");
dso->data.frame_offset = ofs;
}
*offset = ofs;
if (*offset)
return 0;