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authorArnaldo Carvalho de Melo <[email protected]>2017-11-14 11:03:19 -0300
committerArnaldo Carvalho de Melo <[email protected]>2017-11-16 14:50:02 -0300
commit6c4439545517c9d6155e85f1a508be38408fb0b4 (patch)
treefa7a80c6f518c1d8412f9355272d6aead20942ef
parent9c39ed90153d95d362004ed0d5e259ec46af3803 (diff)
perf record: Ignore kptr_restrict when not sampling the kernel
If we're not sampling the kernel, we shouldn't care about kptr_restrict neither synthesize anything for assisting in resolving kernel samples, like the reference relocation symbol or kernel modules information. Before: $ cat /proc/sys/kernel/kptr_restrict /proc/sys/kernel/perf_event_paranoid 2 2 $ perf record sleep 1 WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted, check /proc/sys/kernel/kptr_restrict. Samples in kernel functions may not be resolved if a suitable vmlinux file is not found in the buildid cache or in the vmlinux path. Samples in kernel modules won't be resolved at all. If some relocation was applied (e.g. kexec) symbols may be misresolved even with a suitable vmlinux or kallsyms file. Couldn't record kernel reference relocation symbol Symbol resolution may be skewed if relocation was used (e.g. kexec). Check /proc/kallsyms permission or run as root. [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ] $ perf evlist -v cycles:uppp: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, exclude_kernel: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 $ After: $ perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (10 samples) ] $ Cc: Adrian Hunter <[email protected]> Cc: David Ahern <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Wang Nan <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
-rw-r--r--tools/perf/builtin-record.c26
1 files changed, 14 insertions, 12 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 5f78ce943407..003255910c05 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -765,17 +765,19 @@ static int record__synthesize(struct record *rec, bool tail)
goto out;
}
- err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
- machine);
- WARN_ONCE(err < 0, "Couldn't record kernel reference relocation symbol\n"
- "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
- "Check /proc/kallsyms permission or run as root.\n");
-
- err = perf_event__synthesize_modules(tool, process_synthesized_event,
- machine);
- WARN_ONCE(err < 0, "Couldn't record kernel module information.\n"
- "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
- "Check /proc/modules permission or run as root.\n");
+ if (!perf_evlist__exclude_kernel(rec->evlist)) {
+ err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
+ machine);
+ WARN_ONCE(err < 0, "Couldn't record kernel reference relocation symbol\n"
+ "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
+ "Check /proc/kallsyms permission or run as root.\n");
+
+ err = perf_event__synthesize_modules(tool, process_synthesized_event,
+ machine);
+ WARN_ONCE(err < 0, "Couldn't record kernel module information.\n"
+ "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
+ "Check /proc/modules permission or run as root.\n");
+ }
if (perf_guest) {
machines__process_guests(&session->machines,
@@ -1709,7 +1711,7 @@ int cmd_record(int argc, const char **argv)
err = -ENOMEM;
- if (symbol_conf.kptr_restrict)
+ if (symbol_conf.kptr_restrict && !perf_evlist__exclude_kernel(rec->evlist))
pr_warning(
"WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,\n"
"check /proc/sys/kernel/kptr_restrict.\n\n"