diff options
author | Namhyung Kim <namhyung@kernel.org> | 2023-07-24 17:19:29 -0700 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2023-07-28 19:01:16 -0300 |
commit | 69a87a32f5cd8b262cb2195b045f96c63aede734 (patch) | |
tree | eac3256e20772fbad7d137afb4a2ac1ebd6b03e8 /tools/perf/util/machine.c | |
parent | f9dd531c5b82037f0f8f9ffc04ce0c09840fba2e (diff) |
perf machine: Include data symbols in the kernel map
When 'perf record -d' is used, it needs data mmaps to symbolize global
data. But it missed to collect kernel data maps so it cannot symbolize
them. Instead of having a separate map, just increase the kernel map
size to include the data section.
Probably we can have a separate kernel map for data, but the current
code assumes a single kernel map. So it'd require more changes in other
places and looks error-prone. I decided not to go that way for now.
Also it seems the kernel module size already includes the data section.
For example, my system has the following.
$ grep -e _stext -e _etext -e _edata /proc/kallsyms
ffffffff99800000 T _stext
ffffffff9a601ac8 T _etext
ffffffff9b446a00 D _edata
Size of the text section is (0x9a601ac8 - 0x99800000 = 0xe01ac8) and
size including data section is (0x9b446a00 - 0x99800000 = 0x1c46a00).
Before:
$ perf record -d true
$ perf report -D | grep MMAP | head -1
0 0 0x460 [0x60]: PERF_RECORD_MMAP -1/0: [0xffffffff99800000(0xe01ac8) @ 0xffffffff99800000]: x [kernel.kallsyms]_text
^^^^^^^^
here
After:
$ perf report -D | grep MMAP | head -1
0 0 0x460 [0x60]: PERF_RECORD_MMAP -1/0: [0xffffffff99800000(0x1c46a00) @ 0xffffffff99800000]: x [kernel.kallsyms]_text
^^^^^^^^^
Instead of just replacing it to _edata, try _edata first and then fall
back to _etext just in case.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230725001929.368041-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/machine.c')
-rw-r--r-- | tools/perf/util/machine.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 4e62843d51b7..11de3ca8d4fa 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1216,7 +1216,9 @@ static int machine__get_running_kernel_start(struct machine *machine, *start = addr; - err = kallsyms__get_function_start(filename, "_etext", &addr); + err = kallsyms__get_symbol_start(filename, "_edata", &addr); + if (err) + err = kallsyms__get_function_start(filename, "_etext", &addr); if (!err) *end = addr; |