perf tools: Make it possible to see perf's kernel and module memory m…

…appings

Dump kmaps if using 'perf --debug kmaps' or verbose > 2 (e.g. -vvv) for
tools 'perf script' and 'perf report' if there is no browser.

Example:

  $ perf --debug kmaps script 2>&1 >/dev/null | grep kvm.intel
  build id event received for /lib/modules/6.7.2-local/kernel/arch/x86/kvm/kvm-intel.ko: 0691d75e10e72ebbbd45a44c59f6d00a5604badf [20]
  Map: 0-3a3 4f5d8 [kvm_intel].modinfo
  Map: 0-5240 5f280 [kvm_intel]__versions
  Map: 0-30 64 [kvm_intel].note.Linux
  Map: 0-14 644c0 [kvm_intel].orc_header
  Map: 0-5297 43680 [kvm_intel].rodata
  Map: 0-5bee 3b837 [kvm_intel].text.unlikely
  Map: 0-7e0 41430 [kvm_intel].noinstr.text
  Map: 0-2080 713c0 [kvm_intel].bss
  Map: 0-26 705c8 [kvm_intel].data..read_mostly
  Map: 0-5888 6a4c0 [kvm_intel].data
  Map: 0-22 70220 [kvm_intel].data.once
  Map: 0-40 705f0 [kvm_intel].data..percpu
  Map: 0-1685 41d20 [kvm_intel].init.text
  Map: 0-4b8 6fd60 [kvm_intel].init.data
  Map: 0-380 70248 [kvm_intel]__dyndbg
  Map: 0-8 70218 [kvm_intel].exit.data
  Map: 0-438 4f980 [kvm_intel]__param
  Map: 0-5f5 4ca0f [kvm_intel].rodata.str1.1
  Map: 0-3657 493b8 [kvm_intel].rodata.str1.8
  Map: 0-e0 70640 [kvm_intel].data..ro_after_init
  Map: 0-500 70ec0 [kvm_intel].gnu.linkonce.this_module
  Map: ffffffffc13a7000-ffffffffc1421000 a0 /lib/modules/6.7.2-local/kernel/arch/x86/kvm/kvm-intel.ko

The example above shows how the module section mappings are all wrong
except for the main .text mapping at 0xffffffffc13a7000.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Like Xu <like.xu.linux@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240208085326.13432-2-adrian.hunter@intel.com

tools/perf/Documentation/perf.txt

@@ -63,6 +63,8 @@ OPTIONS
                              in browser mode
           perf-event-open  - Print perf_event_open() arguments and
                              return value
+          kmaps            - Print kernel and module maps (perf script
+                             and perf report without browser)
 
 --debug-file::
 	Write debug output to a specified file.

tools/perf/builtin-report.c

@@ -1766,6 +1766,8 @@ int cmd_report(int argc, const char **argv)
 	} else
 		ret = 0;
 
+	if (!use_browser && (verbose > 2 || debug_kmaps))
+		perf_session__dump_kmaps(session);
 error:
 	if (report.ptime_range) {
 		itrace_synth_opts__clear_time_range(&itrace_synth_opts);

tools/perf/builtin-script.c

@@ -4378,6 +4378,9 @@ int cmd_script(int argc, const char **argv)
 
 	flush_scripting();
 
+	if (verbose > 2 || debug_kmaps)
+		perf_session__dump_kmaps(session);
+
 out_delete:
 	if (script.ptime_range) {
 		itrace_synth_opts__clear_time_range(&itrace_synth_opts);

tools/perf/util/debug.c

@@ -33,6 +33,7 @@
 #endif
 
 int verbose;
+int debug_kmaps;
 int debug_peo_args;
 bool dump_trace = false, quiet = false;
 int debug_ordered_events;
@@ -229,6 +230,7 @@ static struct sublevel_option debug_opts[] = {
 	{ .name = "stderr",		.value_ptr = &redirect_to_stderr},
 	{ .name = "data-convert",	.value_ptr = &debug_data_convert },
 	{ .name = "perf-event-open",	.value_ptr = &debug_peo_args },
+	{ .name = "kmaps",		.value_ptr = &debug_kmaps },
 	{ .name = NULL, }
 };
 
@@ -267,6 +269,7 @@ int perf_quiet_option(void)
 	/* For debug variables that are used as bool types, set to 0. */
 	redirect_to_stderr = 0;
 	debug_peo_args = 0;
+	debug_kmaps = 0;
 
 	return 0;
 }

tools/perf/util/debug.h

@@ -9,6 +9,7 @@
 #include <linux/compiler.h>
 
 extern int verbose;
+extern int debug_kmaps;
 extern int debug_peo_args;
 extern bool quiet, dump_trace;
 extern int debug_ordered_events;

tools/perf/util/python.c

@@ -181,6 +181,7 @@ int perf_bpf_filter__destroy(struct evsel *evsel __maybe_unused)
  * implementing 'verbose' and 'eprintf'.
  */
 int verbose;
+int debug_kmaps;
 int debug_peo_args;
 
 int eprintf(int level, int var, const char *fmt, ...);

tools/perf/util/session.c

@@ -2720,6 +2720,17 @@ size_t perf_session__fprintf(struct perf_session *session, FILE *fp)
 	return machine__fprintf(&session->machines.host, fp);
 }
 
+void perf_session__dump_kmaps(struct perf_session *session)
+{
+	int save_verbose = verbose;
+
+	fflush(stdout);
+	fprintf(stderr, "Kernel and module maps:\n");
+	verbose = 0; /* Suppress verbose to print a summary only */
+	maps__fprintf(machine__kernel_maps(&session->machines.host), stderr);
+	verbose = save_verbose;
+}
+
 struct evsel *perf_session__find_first_evtype(struct perf_session *session,
 					      unsigned int type)
 {

tools/perf/util/session.h

@@ -133,6 +133,8 @@ size_t perf_session__fprintf_dsos_buildid(struct perf_session *session, FILE *fp
 size_t perf_session__fprintf_nr_events(struct perf_session *session, FILE *fp,
 				       bool skip_empty);
 
+void perf_session__dump_kmaps(struct perf_session *session);
+
 struct evsel *perf_session__find_first_evtype(struct perf_session *session,
 					    unsigned int type);