Hi Arnaldo,
These 2 patches are in my local tree for a long time. They are
mandatory for android users. Without them resoluting symbol for
Android platform is incorrect for many shared objects.
Namhyung has given his Acked-by to patch 2/2.
Thank you.
Wang Nan (2):
perf tools: Record text offset in dso to calculate objdump address
perf tools: Adjust symbol for shared objects
tools/perf/util/map.c | 14 ++++++++++++++
tools/perf/util/symbol-elf.c | 13 +++----------
2 files changed, 17 insertions(+), 10 deletions(-)
--
1.8.3.4
In this patch, the offset of '.text' section is stored into dso
and used here to re-calculate address to objdump.
In most of the cases, executable code is in '.text' section, so the
adjustment made to a symbol in dso__load_sym (using
sym.st_value -= shdr.sh_addr - shdr.sh_offset) should equal to
'sym.st_value -= dso->text_offset'. Therefore, adding text_offset back
get objdump address from symbol address (rip). However, it is not true
for kernel and kernel module since there could be multiple executable
sections with different offset. Exclude kernel for this reason.
After this patch, even dso->adjust_symbols is set to true for shared
objects, map__rip_2objdump() and map__objdump_2mem() would return
correct result, so perf behavior of annotate won't be changed.
Signed-off-by: Wang Nan <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Cody P Schafer <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kirill Smelkov <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: [email protected]
---
tools/perf/util/map.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 171b6d1..02c3186 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -431,6 +431,13 @@ u64 map__rip_2objdump(struct map *map, u64 rip)
if (map->dso->rel)
return rip - map->pgoff;
+ /*
+ * kernel modules also have DSO_TYPE_USER in dso->kernel,
+ * but all kernel modules are ET_REL, so won't get here.
+ */
+ if (map->dso->kernel == DSO_TYPE_USER)
+ return rip + map->dso->text_offset;
+
return map->unmap_ip(map, rip) - map->reloc;
}
@@ -454,6 +461,13 @@ u64 map__objdump_2mem(struct map *map, u64 ip)
if (map->dso->rel)
return map->unmap_ip(map, ip + map->pgoff);
+ /*
+ * kernel modules also have DSO_TYPE_USER in dso->kernel,
+ * but all kernel modules are ET_REL, so won't get here.
+ */
+ if (map->dso->kernel == DSO_TYPE_USER)
+ return map->unmap_ip(map, ip - map->dso->text_offset);
+
return ip + map->reloc;
}
--
1.8.3.4
He Kuang reported a problem that perf fails to get correct symbol on
Android platform in [1]. The problem can be reproduced on normal x86_64
platform. I will describe the reproducing steps in detail at the end of
commit message.
The reason of this problem is the missing of symbol adjustment for normal
shared objects. In most of the cases skipping adjustment is okay. However,
when '.text' section have different 'address' and 'offset' the result is wrong.
I checked all shared objects in my working platform, only wine dll objects and
debug objects (in .debug) have this problem. However, it is common on Android.
For example:
$ readelf -S ./libsurfaceflinger.so | grep \.text
[10] .text PROGBITS 0000000000029030 00012030
This patch enables symbol adjustment for dynamic objects so the symbol
address got from elfutils would be adjusted correctly.
Now nearly all types of ELF files should adjust symbols. Makes
ss->adjust_symbols default to true.
Steps to reproduce the problem:
$ cat ./Makefile
PWD := $(shell pwd)
LDFLAGS += "-Wl,-rpath=$(PWD)"
CFLAGS += -g
main: main.c libbuggy.so
libbuggy.so: buggy.c
gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@
clean:
rm -rf main libbuggy.so *.o
$ cat ./buggy.c
int fib(int x)
{
return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2);
}
$ cat ./main.c
#include <stdio.h>
extern int fib(int x);
int main()
{
int i;
for (i = 0; i < 40; i++)
printf("%d\n", fib(i));
return 0;
}
$ make
$ perf record ./main
...
$ perf report --stdio
# Overhead Command Shared Object Symbol
# ........ ....... ................. ...............................
#
14.97% main libbuggy.so [.] 0x000000000000066c
8.68% main libbuggy.so [.] 0x00000000000006aa
8.52% main libbuggy.so [.] fib@plt
7.95% main libbuggy.so [.] 0x0000000000000664
5.94% main libbuggy.so [.] 0x00000000000006a9
5.35% main libbuggy.so [.] 0x0000000000000678
...
The correct result should be (after this patch):
# Overhead Command Shared Object Symbol
# ........ ....... ................. ...............................
#
91.47% main libbuggy.so [.] fib
8.52% main libbuggy.so [.] fib@plt
0.00% main [kernel.kallsyms] [k] kmem_cache_free
[1] http://lkml.kernel.org/g/[email protected]
Signed-off-by: Wang Nan <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Cody P Schafer <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kirill Smelkov <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: [email protected]
---
tools/perf/util/symbol-elf.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index bc229a7..3f9d679 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -709,17 +709,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
if (ss->opdshdr.sh_type != SHT_PROGBITS)
ss->opdsec = NULL;
- if (dso->kernel == DSO_TYPE_USER) {
- GElf_Shdr shdr;
- ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
- ehdr.e_type == ET_REL ||
- dso__is_vdso(dso) ||
- elf_section_by_name(elf, &ehdr, &shdr,
- ".gnu.prelink_undo",
- NULL) != NULL);
- } else {
+ if (dso->kernel == DSO_TYPE_USER)
+ ss->adjust_symbols = true;
+ else
ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
- }
ss->name = strdup(name);
if (!ss->name) {
--
1.8.3.4
Em Thu, Apr 07, 2016 at 10:24:31AM +0000, Wang Nan escreveu:
> He Kuang reported a problem that perf fails to get correct symbol on
> Android platform in [1]. The problem can be reproduced on normal x86_64
> platform. I will describe the reproducing steps in detail at the end of
> commit message.
>
> The reason of this problem is the missing of symbol adjustment for normal
> shared objects. In most of the cases skipping adjustment is okay. However,
> when '.text' section have different 'address' and 'offset' the result is wrong.
> I checked all shared objects in my working platform, only wine dll objects and
> debug objects (in .debug) have this problem. However, it is common on Android.
> For example:
>
> $ readelf -S ./libsurfaceflinger.so | grep \.text
> [10] .text PROGBITS 0000000000029030 00012030
I saved the output of 'perf report' --tui and --stdio before this patch
and after it, it seems to have fixed a few issues with a 'fixdep' binary
generated by by the perf build, things like:
--- perf.hist.before 2016-04-07 16:44:18.220217602 -0300
+++ perf.hist.3 2016-04-07 16:51:18.320693627 -0300
@@ -3538,6 +3538,7 @@
0.01% 0.01% cc1 cc1 [.] cselib_hash_rtx
+ 0.01% 0.00% fixdep fixdep [.] main
0.01% 0.00% CompositorTileW chrome [.] 0xffffaaa40bca467f
@@ -3549,6 +3550,7 @@
0.01% 0.00% ld [unknown] [.] 0x0000559d84243798
+ 0.01% 0.00% fixdep fixdep [.] print_deps
0.01% 0.01% cc1 [kernel.vmlinux] [k] memset_erms
@@ -5916,8 +5918,6 @@
0.01% 0.00% grep [kernel.vmlinux] [k] handle_mm_fault
- 0.01% 0.00% fixdep fixdep [.] 0xffffffffffc00c09
- 0.01% 0.00% fixdep fixdep [.] 0xffffffffffc00c7c
0.01% 0.01% CompositorTileW chrome [.] 0x00000000013ba770
> This patch enables symbol adjustment for dynamic objects so the symbol
> address got from elfutils would be adjusted correctly.
>
> Now nearly all types of ELF files should adjust symbols. Makes
> ss->adjust_symbols default to true.
>
> Steps to reproduce the problem:
Followed them and found the same results as you describe, thanks a lot for doing this!
- Arnaldo
> $ cat ./Makefile
> PWD := $(shell pwd)
> LDFLAGS += "-Wl,-rpath=$(PWD)"
> CFLAGS += -g
> main: main.c libbuggy.so
> libbuggy.so: buggy.c
> gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@
> clean:
> rm -rf main libbuggy.so *.o
>
> $ cat ./buggy.c
> int fib(int x)
> {
> return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2);
> }
>
> $ cat ./main.c
> #include <stdio.h>
>
> extern int fib(int x);
> int main()
> {
> int i;
>
> for (i = 0; i < 40; i++)
> printf("%d\n", fib(i));
> return 0;
> }
>
> $ make
> $ perf record ./main
> ...
> $ perf report --stdio
> # Overhead Command Shared Object Symbol
> # ........ ....... ................. ...............................
> #
> 14.97% main libbuggy.so [.] 0x000000000000066c
> 8.68% main libbuggy.so [.] 0x00000000000006aa
> 8.52% main libbuggy.so [.] fib@plt
> 7.95% main libbuggy.so [.] 0x0000000000000664
> 5.94% main libbuggy.so [.] 0x00000000000006a9
> 5.35% main libbuggy.so [.] 0x0000000000000678
> ...
>
> The correct result should be (after this patch):
>
> # Overhead Command Shared Object Symbol
> # ........ ....... ................. ...............................
> #
> 91.47% main libbuggy.so [.] fib
> 8.52% main libbuggy.so [.] fib@plt
> 0.00% main [kernel.kallsyms] [k] kmem_cache_free
>
> [1] http://lkml.kernel.org/g/[email protected]
>
> Signed-off-by: Wang Nan <[email protected]>
> Acked-by: Namhyung Kim <[email protected]>
> Cc: Adrian Hunter <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Cody P Schafer <[email protected]>
> Cc: He Kuang <[email protected]>
> Cc: Jiri Olsa <[email protected]>
> Cc: Kirill Smelkov <[email protected]>
> Cc: Masami Hiramatsu <[email protected]>
> Cc: Li Zefan <[email protected]>
> Cc: [email protected]
> ---
> tools/perf/util/symbol-elf.c | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index bc229a7..3f9d679 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -709,17 +709,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
> if (ss->opdshdr.sh_type != SHT_PROGBITS)
> ss->opdsec = NULL;
>
> - if (dso->kernel == DSO_TYPE_USER) {
> - GElf_Shdr shdr;
> - ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
> - ehdr.e_type == ET_REL ||
> - dso__is_vdso(dso) ||
> - elf_section_by_name(elf, &ehdr, &shdr,
> - ".gnu.prelink_undo",
> - NULL) != NULL);
> - } else {
> + if (dso->kernel == DSO_TYPE_USER)
> + ss->adjust_symbols = true;
> + else
> ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
> - }
>
> ss->name = strdup(name);
> if (!ss->name) {
> --
> 1.8.3.4
Commit-ID: a58f7033ba892b7d299954b94471450d72623039
Gitweb: http://git.kernel.org/tip/a58f7033ba892b7d299954b94471450d72623039
Author: Wang Nan <[email protected]>
AuthorDate: Thu, 7 Apr 2016 10:24:30 +0000
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Fri, 8 Apr 2016 09:58:14 -0300
perf symbols: Record text offset in dso to calculate objdump address
In this patch, the offset of '.text' section is stored into dso
and used here to re-calculate address to objdump.
In most of the cases, executable code is in '.text' section, so the
adjustment made to a symbol in dso__load_sym (using
sym.st_value -= shdr.sh_addr - shdr.sh_offset) should equal to
'sym.st_value -= dso->text_offset'. Therefore, adding text_offset back
get objdump address from symbol address (rip). However, it is not true
for kernel and kernel module since there could be multiple executable
sections with different offset. Exclude kernel for this reason.
After this patch, even dso->adjust_symbols is set to true for shared
objects, map__rip_2objdump() and map__objdump_2mem() would return
correct result, so perf behavior of annotate won't be changed.
Signed-off-by: Wang Nan <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Cody P Schafer <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kirill Smelkov <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/map.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 171b6d1..02c3186 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -431,6 +431,13 @@ u64 map__rip_2objdump(struct map *map, u64 rip)
if (map->dso->rel)
return rip - map->pgoff;
+ /*
+ * kernel modules also have DSO_TYPE_USER in dso->kernel,
+ * but all kernel modules are ET_REL, so won't get here.
+ */
+ if (map->dso->kernel == DSO_TYPE_USER)
+ return rip + map->dso->text_offset;
+
return map->unmap_ip(map, rip) - map->reloc;
}
@@ -454,6 +461,13 @@ u64 map__objdump_2mem(struct map *map, u64 ip)
if (map->dso->rel)
return map->unmap_ip(map, ip + map->pgoff);
+ /*
+ * kernel modules also have DSO_TYPE_USER in dso->kernel,
+ * but all kernel modules are ET_REL, so won't get here.
+ */
+ if (map->dso->kernel == DSO_TYPE_USER)
+ return map->unmap_ip(map, ip - map->dso->text_offset);
+
return ip + map->reloc;
}
Commit-ID: 99e87f7bb7268cf644add87130590966fd5d0d17
Gitweb: http://git.kernel.org/tip/99e87f7bb7268cf644add87130590966fd5d0d17
Author: Wang Nan <[email protected]>
AuthorDate: Thu, 7 Apr 2016 10:24:31 +0000
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Fri, 8 Apr 2016 09:58:15 -0300
perf symbols: Adjust symbol for shared objects
He Kuang reported a problem that perf fails to get correct symbol on
Android platform in [1]. The problem can be reproduced on normal x86_64
platform. I will describe the reproducing steps in detail at the end of
commit message.
The reason of this problem is the missing of symbol adjustment for normal
shared objects. In most of the cases skipping adjustment is okay. However,
when '.text' section have different 'address' and 'offset' the result is wrong.
I checked all shared objects in my working platform, only wine dll objects and
debug objects (in .debug) have this problem. However, it is common on Android.
For example:
$ readelf -S ./libsurfaceflinger.so | grep \.text
[10] .text PROGBITS 0000000000029030 00012030
This patch enables symbol adjustment for dynamic objects so the symbol
address got from elfutils would be adjusted correctly.
Now nearly all types of ELF files should adjust symbols. Makes
ss->adjust_symbols default to true.
Steps to reproduce the problem:
$ cat ./Makefile
PWD := $(shell pwd)
LDFLAGS += "-Wl,-rpath=$(PWD)"
CFLAGS += -g
main: main.c libbuggy.so
libbuggy.so: buggy.c
gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@
clean:
rm -rf main libbuggy.so *.o
$ cat ./buggy.c
int fib(int x)
{
return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2);
}
$ cat ./main.c
#include <stdio.h>
extern int fib(int x);
int main()
{
int i;
for (i = 0; i < 40; i++)
printf("%d\n", fib(i));
return 0;
}
$ make
$ perf record ./main
...
$ perf report --stdio
# Overhead Command Shared Object Symbol
# ........ ....... ................. ...............................
#
14.97% main libbuggy.so [.] 0x000000000000066c
8.68% main libbuggy.so [.] 0x00000000000006aa
8.52% main libbuggy.so [.] fib@plt
7.95% main libbuggy.so [.] 0x0000000000000664
5.94% main libbuggy.so [.] 0x00000000000006a9
5.35% main libbuggy.so [.] 0x0000000000000678
...
The correct result should be (after this patch):
# Overhead Command Shared Object Symbol
# ........ ....... ................. ...............................
#
91.47% main libbuggy.so [.] fib
8.52% main libbuggy.so [.] fib@plt
0.00% main [kernel.kallsyms] [k] kmem_cache_free
[1] http://lkml.kernel.org/g/[email protected]
Signed-off-by: Wang Nan <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Cody P Schafer <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kirill Smelkov <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol-elf.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index bc229a7..3f9d679 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -709,17 +709,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
if (ss->opdshdr.sh_type != SHT_PROGBITS)
ss->opdsec = NULL;
- if (dso->kernel == DSO_TYPE_USER) {
- GElf_Shdr shdr;
- ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
- ehdr.e_type == ET_REL ||
- dso__is_vdso(dso) ||
- elf_section_by_name(elf, &ehdr, &shdr,
- ".gnu.prelink_undo",
- NULL) != NULL);
- } else {
+ if (dso->kernel == DSO_TYPE_USER)
+ ss->adjust_symbols = true;
+ else
ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
- }
ss->name = strdup(name);
if (!ss->name) {