Hello,
This patchset addresses possible problem on kernel symbol matching.
Since commit 5b7ba82a7591 ("perf symbols: Load kernel maps before
using"), when perf record process samples to construct build-id table,
it loads kernel map and it replaces dso->long_name. But perf report
doesn't know about name other than [kernel.kallsyms] it failed to find
existing kernel dso and falls back to running kernel's kallsyms.
So it's possible to report incorrect symbols for kernel functions if
it runs on a different kernel:
Before:
$ perf report
# Children Self Command Shared Object Symbol
# ........ ........ ....... ................. ...............................
#
72.15% 0.00% swapper [kernel.kallsyms] [k] set_curr_task_rt
72.15% 0.00% swapper [kernel.kallsyms] [k] native_calibrate_tsc
72.15% 0.00% swapper [kernel.kallsyms] [k] tsc_refine_calibration_work
71.87% 71.87% swapper [kernel.kallsyms] [k] module_finalize
...
After (for the same perf.data):
72.15% 0.00% swapper [kernel.vmlinux] [k] cpu_startup_entry
72.15% 0.00% swapper [kernel.vmlinux] [k] arch_cpu_idle
72.15% 0.00% swapper [kernel.vmlinux] [k] default_idle
71.87% 71.87% swapper [kernel.vmlinux] [k] native_safe_halt
In this patch, it's now changed to try to search a kernel dso in the
existing dso list which was constructed during build-id table parsing
so it'll always have a build-id. If not found, search "[kernel.kallsyms]".
The patch 1-2 are to support module compression as some distro
(e.g. Arch) already does it. The patch 3-5 are cleanup of build-id
handling functions. The patch 6-7 are the main change of this series
and finally patch 8 is just for suggestion which can be squashed into
the previous patch or simply dropped.
* changes from v5)
- keep dsos__hit_all() in util/build-id.c (Adrian)
- fix bug in is_kernel_module function (Jiri)
- add missing zlib test to test-all.c (Jiri)
- move disable_buildid_cache function also
You can get it on 'perf/vmlinux-v6' branch in my tree:
git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
Any comments are welcome, thanks
Namhyung
Cc: Adrian Hunter <adrian.hunter@intel.com>
Namhyung Kim (8):
perf tools: Preparation for compressed kernel module support
perf tools: Add gzip decompression support for kernel module
perf tools: Rename dsos__write_buildid_table()
perf build-id: Move build-id related functions to util/build-id.c
perf tools: Move disable_buildid_cache() to util/build-id.c
perf record: Do not save pathname in ./debug/.build-id directory for
vmlinux
perf tools: Fix build-id matching on vmlinux
perf tools: Make vmlinux short name more like kallsyms short name
tools/perf/Makefile.perf | 7 +
tools/perf/builtin-record.c | 11 +
tools/perf/config/Makefile | 15 +-
tools/perf/config/feature-checks/Makefile | 6 +-
tools/perf/config/feature-checks/test-all.c | 5 +
tools/perf/config/feature-checks/test-zlib.c | 9 +
tools/perf/util/build-id.c | 345 ++++++++++++++++++++++++++
tools/perf/util/build-id.h | 12 +
tools/perf/util/dso.c | 71 ++++++
tools/perf/util/dso.h | 7 +
tools/perf/util/header.c | 353 +--------------------------
tools/perf/util/header.h | 8 +-
tools/perf/util/machine.c | 38 ++-
tools/perf/util/symbol-elf.c | 35 ++-
tools/perf/util/symbol.c | 19 +-
tools/perf/util/symbol.h | 1 +
tools/perf/util/util.h | 6 +-
tools/perf/util/zlib.c | 78 ++++++
18 files changed, 658 insertions(+), 368 deletions(-)
create mode 100644 tools/perf/config/feature-checks/test-zlib.c
create mode 100644 tools/perf/util/zlib.c
--
2.1.2
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