perf record: Get ref_reloc_sym from kernel map

Now that ref_reloc_sym is set up when the kernel map is created,
'perf record' does not need to pass the symbol names to
perf_event__synthesize_kernel_mmap() which can read the values needed
from ref_reloc_sym directly.

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/1391004884-10334-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 9 insertions, 30 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 3c394bf16fa8..af47531b82ec 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -287,10 +287,7 @@ static void perf_event__synthesize_guest_os(struct machine *machine, void *data)
          * have no _text sometimes.
          */
         err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
-                                                 machine, "_text");
-        if (err < 0)
-                err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
-                                                         machine, "_stext");
+                                                 machine);
         if (err < 0)
                 pr_err("Couldn't record guest kernel [%d]'s reference"
                        " relocation symbol.\n", machine->pid);
@@ -457,10 +454,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
         }
 
         err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
-                                                 machine, "_text");
-        if (err < 0)
-                err = perf_event__synthesize_kernel_mmap(tool, process_synthesized_event,
-                                                         machine, "_stext");
+                                                 machine);
         if (err < 0)
                 pr_err("Couldn't record kernel reference relocation symbol\n"
                        "Symbol resolution may be skewed if relocation was used (e.g. kexec).\n"
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 17476df5c7b2..b0f3ca850e9e 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -483,15 +483,13 @@ u64 kallsyms__get_function_start(const char *kallsyms_filename,
 
 int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
                                        perf_event__handler_t process,
-                                       struct machine *machine,
-                                       const char *symbol_name)
+                                       struct machine *machine)
 {
         size_t size;
-        const char *filename, *mmap_name;
-        char path[PATH_MAX];
+        const char *mmap_name;
         char name_buff[PATH_MAX];
         struct map *map;
-        u64 start;
+        struct kmap *kmap;
         int err;
         /*
          * We should get this from /sys/kernel/sections/.text, but till that is
@@ -513,31 +511,19 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
                  * see kernel/perf_event.c __perf_event_mmap
                  */
                 event->header.misc = PERF_RECORD_MISC_KERNEL;
-                filename = "/proc/kallsyms";
         } else {
                 event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
-                if (machine__is_default_guest(machine))
-                        filename = (char *) symbol_conf.default_guest_kallsyms;
-                else {
-                        sprintf(path, "%s/proc/kallsyms", machine->root_dir);
-                        filename = path;
-                }
-        }
-
-        start = kallsyms__get_function_start(filename, symbol_name);
-        if (!start) {
-                free(event);
-                return -ENOENT;
         }
 
         map = machine->vmlinux_maps[MAP__FUNCTION];
+        kmap = map__kmap(map);
         size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
-                        "%s%s", mmap_name, symbol_name) + 1;
+                        "%s%s", mmap_name, kmap->ref_reloc_sym->name) + 1;
         size = PERF_ALIGN(size, sizeof(u64));
         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 = start;
+        event->mmap.pgoff = kmap->ref_reloc_sym->addr;
         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 66a0c0392863..851fa06f4a42 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -214,8 +214,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
                                    struct machine *machine, bool mmap_data);
 int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
                                        perf_event__handler_t process,
-                                       struct machine *machine,
-                                       const char *symbol_name);
+                                       struct machine *machine);
 
 int perf_event__synthesize_modules(struct perf_tool *tool,
                                    perf_event__handler_t process,