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-rw-r--r--tools/perf/builtin-report.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 498c6f7..99156c3 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -116,6 +116,9 @@ static int process_sample_event(union perf_event *event,
if (al.filtered || (hide_unresolved && al.sym == NULL))
return 0;
+ if (al.map != NULL)
+ al.map->dso->hit = 1;
+
if (perf_session__add_hist_entry(session, &al, sample, evsel)) {
pr_debug("problem incrementing symbol period, skipping event\n");
return -1;
@@ -249,6 +252,8 @@ static int __cmd_report(void)
u64 nr_samples;
struct perf_session *session;
struct perf_evsel *pos;
+ struct map *kernel_map;
+ struct kmap *kernel_kmap;
const char *help = "For a higher level overview, try: perf report --sort comm,dso";
signal(SIGINT, sig_handler);
@@ -268,6 +273,27 @@ static int __cmd_report(void)
if (ret)
goto out_delete;
+ kernel_map = session->host_machine.vmlinux_maps[MAP__FUNCTION];
+ kernel_kmap = map__kmap(kernel_map);
+ if (kernel_map == NULL ||
+ (kernel_map->dso->hit &&
+ (kernel_kmap->ref_reloc_sym == NULL ||
+ kernel_kmap->ref_reloc_sym->addr == 0))) {
+ const struct dso *kdso = kernel_map->dso;
+
+ ui__warning("Kernel address maps "
+ "(/proc/{kallsyms,modules}) were restricted, "
+ "check /proc/sys/kernel/kptr_restrict before "
+ "running 'perf record'.\n\n%s\n\n"
+ "Samples in kernel modules can't be resolved "
+ "as well.\n\n",
+ RB_EMPTY_ROOT(&kdso->symbols[MAP__FUNCTION]) ?
+ "As no suitable kallsyms nor vmlinux was found, "
+ "kernel samples can't be resolved." :
+ "If some relocation was applied (e.g. kexec) "
+ "symbols may be misresolved.");
+ }
+
if (dump_trace) {
perf_session__fprintf_nr_events(session, stdout);
goto out_delete;