kernel-fxtec-pro1x/tools/perf/util/vdso.c
Jiri Olsa 7dbf4dcfe2 perf tools: Back [vdso] DSO with real data
Storing data for VDSO shared object, because we need it for the post
unwind processing.

The VDSO shared object is same for all process on a running system, so
it makes no difference when we store it inside the tracer - perf.

When [vdso] map memory is hit, we retrieve [vdso] DSO image and store it
into temporary file.

During the build-id processing phase, the [vdso] DSO image is stored in
build-id db, and build-id reference is made inside perf.data. The
build-id vdso file object is called '[vdso]'. We don't use temporary
file name which gets removed when record is finished.

During report phase the vdso build-id object is treated as any other
build-id DSO object.

Adding following API for vdso object:

  bool is_vdso_map(const char *filename)
    - returns true if the filename matches vdso map name

  struct dso *vdso__dso_findnew(struct list_head *head)
    - find/create proper vdso DSO object

  vdso__exit(void)
    - removes temporary VDSO image if there's any

This change makes backtrace dwarf post unwind possible from [vdso] maps.

Following output is current report of [vdso] sample dwarf backtrace:

  # Overhead  Command      Shared Object                         Symbol
  # ........  .......  .................  .............................
  #
      99.52%       ex  [vdso]             [.] 0x00007fff3ace89af
                   |
                   --- 0x7fff3ace89af

Following output is new report of [vdso] sample dwarf backtrace:

  # Overhead  Command      Shared Object                         Symbol
  # ........  .......  .................  .............................
  #
      99.52%       ex  [vdso]             [.] 0x00000000000009af
                   |
                   --- 0x7fff3ace89af
                       main
                       __libc_start_main
                       _start

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347295819-23177-5-git-send-email-jolsa@redhat.com
[ committer note: s/ALIGN/PERF_ALIGN/g to cope with the android build changes ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2012-09-11 12:08:30 -03:00

111 lines
1.7 KiB
C

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <linux/kernel.h>
#include "vdso.h"
#include "util.h"
#include "symbol.h"
#include "linux/string.h"
static bool vdso_found;
static char vdso_file[] = "/tmp/perf-vdso.so-XXXXXX";
static int find_vdso_map(void **start, void **end)
{
FILE *maps;
char line[128];
int found = 0;
maps = fopen("/proc/self/maps", "r");
if (!maps) {
pr_err("vdso: cannot open maps\n");
return -1;
}
while (!found && fgets(line, sizeof(line), maps)) {
int m = -1;
/* We care only about private r-x mappings. */
if (2 != sscanf(line, "%p-%p r-xp %*x %*x:%*x %*u %n",
start, end, &m))
continue;
if (m < 0)
continue;
if (!strncmp(&line[m], VDSO__MAP_NAME,
sizeof(VDSO__MAP_NAME) - 1))
found = 1;
}
fclose(maps);
return !found;
}
static char *get_file(void)
{
char *vdso = NULL;
char *buf = NULL;
void *start, *end;
size_t size;
int fd;
if (vdso_found)
return vdso_file;
if (find_vdso_map(&start, &end))
return NULL;
size = end - start;
buf = memdup(start, size);
if (!buf)
return NULL;
fd = mkstemp(vdso_file);
if (fd < 0)
goto out;
if (size == (size_t) write(fd, buf, size))
vdso = vdso_file;
close(fd);
out:
free(buf);
vdso_found = (vdso != NULL);
return vdso;
}
void vdso__exit(void)
{
if (vdso_found)
unlink(vdso_file);
}
struct dso *vdso__dso_findnew(struct list_head *head)
{
struct dso *dso = dsos__find(head, VDSO__MAP_NAME);
if (!dso) {
char *file;
file = get_file();
if (!file)
return NULL;
dso = dso__new(VDSO__MAP_NAME);
if (dso != NULL) {
dsos__add(head, dso);
dso__set_long_name(dso, file);
}
}
return dso;
}