perf callchain: Separate eh/debug frame offset cache.

Commit f1f13af99a90 ("perf callchain: Cache eh/debug frame offset for
dwarf unwind") introduces a cache for .debug_frame and .eh_frame_hdr.
Unfortunately, it makes them share a same cache (dso->frame_offset).
Which causes unwind failure on ARM:

   $ perf test unwind
  Test dwarf unwind: FAILED!

The reason is that, if a dso has '.debug_frame' but doesn't have
'.eh_frame_hdr' (like ARM), dso->frame_offset will be filled by offset
of '.debug_frame' during the first time calling of find_proc_info() ->
read_unwind_spec_debug_frame(), and be regarded to '.eh_frame_hdr' when
the second time calling of find_proc_info() ->
read_unwind_spec_eh_frame(), since '.eh_frame_hdr' is checked prior to
'.debug_frame'.

This patch solves the problem by creating two cache fields for
'.eh_frame_hdr' and '.debug_frame'.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/55028BA0.1030701@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 6 insertions, 5 deletions

diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index ced92841ff97..408c65f1a757 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -139,7 +139,8 @@ struct dso {
                 u32              status_seen;
                 size_t           file_size;
                 struct list_head open_entry;
-                u64              frame_offset;
+                u64              debug_frame_offset;
+                u64              eh_frame_hdr_offset;
         } data;
 
         union { /* Tool specific area */
diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index e3c40a520a25..7b09a443a280 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -266,7 +266,7 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
                                      u64 *fde_count)
 {
         int ret = -EINVAL, fd;
-        u64 offset = dso->data.frame_offset;
+        u64 offset = dso->data.eh_frame_hdr_offset;
 
         if (offset == 0) {
                 fd = dso__data_fd(dso, machine);
@@ -275,7 +275,7 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
 
                 /* Check the .eh_frame section for unwinding info */
                 offset = elf_section_offset(fd, ".eh_frame_hdr");
-                dso->data.frame_offset = offset;
+                dso->data.eh_frame_hdr_offset = offset;
         }
 
         if (offset)
@@ -291,7 +291,7 @@ static int read_unwind_spec_debug_frame(struct dso *dso,
                                         struct machine *machine, u64 *offset)
 {
         int fd;
-        u64 ofs = dso->data.frame_offset;
+        u64 ofs = dso->data.debug_frame_offset;
 
         if (ofs == 0) {
                 fd = dso__data_fd(dso, machine);
@@ -300,7 +300,7 @@ static int read_unwind_spec_debug_frame(struct dso *dso,
 
                 /* Check the .debug_frame section for unwinding info */
                 ofs = elf_section_offset(fd, ".debug_frame");
-                dso->data.frame_offset = ofs;
+                dso->data.debug_frame_offset = ofs;
         }
 
         *offset = ofs;