This is a note to let you know that I've just added the patch titled
perf machine: Include data symbols in the kernel map
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-machine-include-data-symbols-in-the-kernel-map.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d9b0d9f13d180a904a07c9bfea4ecad3ab4d7d12
Author: Namhyung Kim <namhyung@xxxxxxxxxx>
Date: Mon Jul 24 17:19:29 2023 -0700
perf machine: Include data symbols in the kernel map
[ Upstream commit 69a87a32f5cd8b262cb2195b045f96c63aede734 ]
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@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230725001929.368041-2-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Stable-dep-of: 7a93786c3062 ("perf machine: Don't ignore _etext when not a text symbol")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 8c3addc2e9e1e..e7f970681efce 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -950,7 +950,9 @@ 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;
