Applies to linux-2.6-tip/master or acme/perf-core
ARM ELF files use symbols with special names $a, $t, $d to
identify regions of ARM code, Thumb code and data within code
sections. This can cause confusing output from the perf tools,
especially for partially stripped binaries, or binaries
containing user-added zero-sized symbols (which may occur in
hand-written assembler which hasn't been fully annotated with
.size directives).
This patch filters out these symbols at load time.
Addressing architecture-specific cases in this way could get
quite messy-- if one architecture-specific hack is needed in
the symbol loading loop, more might be needed over time.
Adding a generic per-architecture symbol filtering hook might
help to mitigate this if more cases need to be supported.
Switching to libbfd as a generic image-handling backend for all
architectures might be a better long-term solution, since
libelf seems to be essentially a low-level parsing library only
at this stage, and doesn't deal with all the architecture
specifics. There's a generic bfd_is_target_special_symbol()
function which is used by binutils to filter out architecture-
specific symbols which are not "normal" symbols, which could
help us for this case.
Dave Martin (1):
perf symbols: ignore mapping symbols on ARM
tools/perf/util/symbol.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
Applies to linux-2.6-tip/master or acme/perf-core
ARM ELF files use symbols with special names $a, $t, $d to
identify regions of ARM code, Thumb code and data within code
sections. This can cause confusing output from the perf tools,
especially for partially stripped binaries, or binaries
containing user-added zero-sized symbols (which may occur in
hand-written assembler which hasn't been fully annotated with
.size directives).
This patch filters out these symbols at load time.
Signed-off-by: Dave Martin <[email protected]>
---
tools/perf/util/symbol.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b6f5970..1a36773 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1079,6 +1079,16 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
if (!is_label && !elf_sym__is_a(&sym, map->type))
continue;
+ /* Reject ARM ELF "mapping symbols": these aren't unique and
+ * don't identify functions, so will confuse the profile
+ * output: */
+ if (ehdr.e_machine == EM_ARM) {
+ if (!strcmp(elf_name, "$a") ||
+ !strcmp(elf_name, "$d") ||
+ !strcmp(elf_name, "$t"))
+ continue;
+ }
+
if (opdsec && sym.st_shndx == opdidx) {
u32 offset = sym.st_value - opdshdr.sh_addr;
u64 *opd = opddata->d_buf + offset;
--
1.7.0.4
Em Mon, Aug 09, 2010 at 12:21:18PM +0100, Dave Martin escreveu:
> + /* Reject ARM ELF "mapping symbols": these aren't unique and
> + * don't identify functions, so will confuse the profile
> + * output: */
> + if (ehdr.e_machine == EM_ARM) {
> + if (!strcmp(elf_name, "$a") ||
> + !strcmp(elf_name, "$d") ||
> + !strcmp(elf_name, "$t"))
> + continue;
> + }
> +
Thanks, applied.
Commit-ID: 696b97a5d2de9e2b22699300835e675dfffe8592
Gitweb: http://git.kernel.org/tip/696b97a5d2de9e2b22699300835e675dfffe8592
Author: Dave Martin <[email protected]>
AuthorDate: Mon, 9 Aug 2010 12:21:18 +0100
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Tue, 10 Aug 2010 16:10:36 -0300
perf symbols: Ignore mapping symbols on ARM
ARM ELF files use symbols with special names $a, $t, $d to identify regions of
ARM code, Thumb code and data within code sections. This can cause confusing
output from the perf tools, especially for partially stripped binaries, or
binaries containing user-added zero-sized symbols (which may occur in
hand-written assembler which hasn't been fully annotated with .size
directives).
This patch filters out these symbols at load time.
LKML-Reference: <[email protected]>
Signed-off-by: Dave Martin <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b6f5970..1a36773 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1079,6 +1079,16 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
if (!is_label && !elf_sym__is_a(&sym, map->type))
continue;
+ /* Reject ARM ELF "mapping symbols": these aren't unique and
+ * don't identify functions, so will confuse the profile
+ * output: */
+ if (ehdr.e_machine == EM_ARM) {
+ if (!strcmp(elf_name, "$a") ||
+ !strcmp(elf_name, "$d") ||
+ !strcmp(elf_name, "$t"))
+ continue;
+ }
+
if (opdsec && sym.st_shndx == opdidx) {
u32 offset = sym.st_value - opdshdr.sh_addr;
u64 *opd = opddata->d_buf + offset;