perf tools: Add kallsyms__get_function_start()

Separate out the logic used to find the start address of the reference
symbol used to track kernel relocation.  kallsyms__get_function_start()
is used in subsequent patches.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1391004884-10334-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 1fc1c2f..17476df 100644 (file)
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -470,6 +470,17 @@ static int find_symbol_cb(void *arg, const char *name, char type,
        return 1;
 }
 
+u64 kallsyms__get_function_start(const char *kallsyms_filename,
+                                const char *symbol_name)
+{
+       struct process_symbol_args args = { .name = symbol_name, };
+
+       if (kallsyms__parse(kallsyms_filename, &args, find_symbol_cb) <= 0)
+               return 0;
+
+       return args.start;
+}
+
 int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
                                       perf_event__handler_t process,
                                       struct machine *machine,
@@ -480,13 +491,13 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
        char path[PATH_MAX];
        char name_buff[PATH_MAX];
        struct map *map;
+       u64 start;
        int err;
        /*
         * We should get this from /sys/kernel/sections/.text, but till that is
         * available use this, and after it is use this as a fallback for older
         * kernels.
         */
-       struct process_symbol_args args = { .name = symbol_name, };
        union perf_event *event = zalloc((sizeof(event->mmap) +
                                          machine->id_hdr_size));
        if (event == NULL) {
@@ -513,7 +524,8 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
                }
        }
 
-       if (kallsyms__parse(filename, &args, find_symbol_cb) <= 0) {
+       start = kallsyms__get_function_start(filename, symbol_name);
+       if (!start) {
                free(event);
                return -ENOENT;
        }
@@ -525,7 +537,7 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
        event->mmap.header.type = PERF_RECORD_MMAP;
        event->mmap.header.size = (sizeof(event->mmap) -
                        (sizeof(event->mmap.filename) - size) + machine->id_hdr_size);
-       event->mmap.pgoff = args.start;
+       event->mmap.pgoff = start;
        event->mmap.start = map->start;
        event->mmap.len   = map->end - event->mmap.start;
        event->mmap.pid   = machine->pid;

diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index faf6e21..66a0c03 100644 (file)
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -279,4 +279,7 @@ size_t perf_event__fprintf_mmap2(union perf_event *event, FILE *fp);
 size_t perf_event__fprintf_task(union perf_event *event, FILE *fp);
 size_t perf_event__fprintf(union perf_event *event, FILE *fp);
 
+u64 kallsyms__get_function_start(const char *kallsyms_filename,
+                                const char *symbol_name);
+
 #endif /* __PERF_RECORD_H */