perf report: Allow user to specify path to kallsyms file

This is useful for analyzing a perf data file on a different system than
the one data was collected on and still include symbols from loaded
kernel modules in the output.

Commiter note: Updated the man page accordingly.

LKML-Reference: <1291775986-16475-1-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 13 insertions, 2 deletions

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 59a1f57f2bb7..fefea77ec6e9 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -104,6 +104,9 @@ OPTIONS
 --vmlinux=<file>::
         vmlinux pathname
 
+--kallsyms=<file>::
+        kallsyms pathname
+
 -m::
 --modules::
         Load module symbols. WARNING: This should only be used with -k and
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 904519fba434..b6a2a899aa8f 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -443,6 +443,8 @@ static const struct option options[] = {
                     "dump raw trace in ASCII"),
         OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
                    "file", "vmlinux pathname"),
+        OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
+                   "file", "kallsyms pathname"),
         OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
         OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
                     "load module symbols - WARNING: use only with -k and LIVE kernel"),
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a348906b587d..f40c076aeb7b 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1830,8 +1830,8 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
         const char *kallsyms_filename = NULL;
         char *kallsyms_allocated_filename = NULL;
         /*
-         * Step 1: if the user specified a vmlinux filename, use it and only
-         * it, reporting errors to the user if it cannot be used.
+         * Step 1: if the user specified a kallsyms or vmlinux filename, use
+         * it and only it, reporting errors to the user if it cannot be used.
          *
          * For instance, try to analyse an ARM perf.data file _without_ a
          * build-id, or if the user specifies the wrong path to the right
@@ -1844,6 +1844,11 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
          * validation in dso__load_vmlinux and will bail out if they don't
          * match.
          */
+        if (symbol_conf.kallsyms_name != NULL) {
+                kallsyms_filename = symbol_conf.kallsyms_name;
+                goto do_kallsyms;
+        }
+
         if (symbol_conf.vmlinux_name != NULL) {
                 err = dso__load_vmlinux(self, map,
                                         symbol_conf.vmlinux_name, filter);
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 038f2201ee09..12defbe18c13 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -72,6 +72,7 @@ struct symbol_conf {
                         show_cpu_utilization,
                         initialized;
         const char      *vmlinux_name,
+                        *kallsyms_name,
                         *source_prefix,
                         *field_sep;
         const char      *default_guest_vmlinux_name,