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: Namhyung 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: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -139,6 +139,7 @@ struct dso {
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u32 status_seen;
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size_t file_size;
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struct list_head open_entry;
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u64 frame_offset;
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} data;
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union { /* Tool specific area */
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@ -266,14 +266,17 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
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u64 *fde_count)
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{
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int ret = -EINVAL, fd;
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u64 offset;
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u64 offset = dso->data.frame_offset;
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if (offset == 0) {
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fd = dso__data_fd(dso, machine);
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if (fd < 0)
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return -EINVAL;
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/* Check the .eh_frame section for unwinding info */
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offset = elf_section_offset(fd, ".eh_frame_hdr");
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dso->data.frame_offset = offset;
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}
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if (offset)
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ret = unwind_spec_ehframe(dso, machine, offset,
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@ -287,14 +290,20 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
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static int read_unwind_spec_debug_frame(struct dso *dso,
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struct machine *machine, u64 *offset)
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{
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int fd = dso__data_fd(dso, machine);
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int fd;
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u64 ofs = dso->data.frame_offset;
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if (ofs == 0) {
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fd = dso__data_fd(dso, machine);
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if (fd < 0)
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return -EINVAL;
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/* Check the .debug_frame section for unwinding info */
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*offset = elf_section_offset(fd, ".debug_frame");
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ofs = elf_section_offset(fd, ".debug_frame");
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dso->data.frame_offset = ofs;
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}
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*offset = ofs;
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if (*offset)
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return 0;
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