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authorNamhyung Kim <namhyung@kernel.org>2023-07-24 17:19:29 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2023-07-28 19:01:16 -0300
commit69a87a32f5cd8b262cb2195b045f96c63aede734 (patch)
treeeac3256e20772fbad7d137afb4a2ac1ebd6b03e8 /tools/perf/util/machine.c
parentf9dd531c5b82037f0f8f9ffc04ce0c09840fba2e (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.c4
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;