Thread (1 message) 1 message, 1 author, 2025-02-05
STALE541d

[PATCH 6.12 270/590] perf machine: Dont ignore _etext when not a text symbol

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2025-02-05 14:32:29
Also in: linux-patches, stable
Subsystem: performance events subsystem, the rest · Maintainers: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Leroy <redacted>

[ Upstream commit 7a93786c306296f15e728b1dbd949a319e4e3d19 ]

Depending on how vmlinux.lds is written, _etext might be the very first
data symbol instead of the very last text symbol.

Don't require it to be a text symbol, accept any symbol type.

Comitter notes:

See the first Link for further discussion, but it all boils down to
this:

 ---
  # grep -e _stext -e _etext -e _edata /proc/kallsyms
  c0000000 T _stext
  c08b8000 D _etext

  So there is no _edata and _etext is not text

  $ ppc-linux-objdump -x vmlinux | grep -e _stext -e _etext -e _edata
  c0000000 g       .head.text	00000000 _stext
  c08b8000 g       .rodata	00000000 _etext
  c1378000 g       .sbss	00000000 _edata
 ---

Fixes: ed9adb2035b5be58 ("perf machine: Read also the end of the kernel")
Signed-off-by: Christophe Leroy <redacted>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <redacted>
Link: https://lore.kernel.org/r/b3ee1994d95257cb7f2de037c5030ba7d1bed404.1736327613.git.christophe.leroy@csgroup.eu (local)
Signed-off-by: Arnaldo Carvalho de Melo <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/util/machine.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 27d5345d2b307..9be2f4479f525 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1003,7 +1003,7 @@ static int machine__get_running_kernel_start(struct machine *machine,
 
 	err = kallsyms__get_symbol_start(filename, "_edata", &addr);
 	if (err)
-		err = kallsyms__get_function_start(filename, "_etext", &addr);
+		err = kallsyms__get_symbol_start(filename, "_etext", &addr);
 	if (!err)
 		*end = addr;
 
-- 
2.39.5



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