linux/tools/perf/util/vdso.c
Arnaldo Carvalho de Melo d3a7c489c7 perf tools: Reference count struct dso
This has a different model than the 'thread' and 'map' struct lifetimes:
there is not a definitive "don't use this DSO anymore" event, i.e. we may
get many 'struct map' holding references to the '/usr/lib64/libc-2.20.so'
DSO but then at some point some DSO may have no references but we still
don't want to straight away release its resources, because "soon" we may
get a new 'struct map' that needs it and we want to reuse its symtab or
other resources.

So we need some way to garbage collect it when crossing some memory
usage threshold, which is left for anoter patch, for now it is
sufficient to release it when calling dsos__exit(), i.e. when deleting
the whole list as part of deleting the 'struct machine' containing it,
which will leave only referenced objects being used.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/tip-majzgz07cm90t2tejrjy4clf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-06-08 10:31:40 -03:00

328 lines
6.4 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 "machine.h"
#include "thread.h"
#include "linux/string.h"
#include "debug.h"
/*
* Include definition of find_vdso_map() also used in perf-read-vdso.c for
* building perf-read-vdso32 and perf-read-vdsox32.
*/
#include "find-vdso-map.c"
#define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
struct vdso_file {
bool found;
bool error;
char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
const char *dso_name;
const char *read_prog;
};
struct vdso_info {
struct vdso_file vdso;
#if BITS_PER_LONG == 64
struct vdso_file vdso32;
struct vdso_file vdsox32;
#endif
};
static struct vdso_info *vdso_info__new(void)
{
static const struct vdso_info vdso_info_init = {
.vdso = {
.temp_file_name = VDSO__TEMP_FILE_NAME,
.dso_name = DSO__NAME_VDSO,
},
#if BITS_PER_LONG == 64
.vdso32 = {
.temp_file_name = VDSO__TEMP_FILE_NAME,
.dso_name = DSO__NAME_VDSO32,
.read_prog = "perf-read-vdso32",
},
.vdsox32 = {
.temp_file_name = VDSO__TEMP_FILE_NAME,
.dso_name = DSO__NAME_VDSOX32,
.read_prog = "perf-read-vdsox32",
},
#endif
};
return memdup(&vdso_info_init, sizeof(vdso_info_init));
}
static char *get_file(struct vdso_file *vdso_file)
{
char *vdso = NULL;
char *buf = NULL;
void *start, *end;
size_t size;
int fd;
if (vdso_file->found)
return vdso_file->temp_file_name;
if (vdso_file->error || find_vdso_map(&start, &end))
return NULL;
size = end - start;
buf = memdup(start, size);
if (!buf)
return NULL;
fd = mkstemp(vdso_file->temp_file_name);
if (fd < 0)
goto out;
if (size == (size_t) write(fd, buf, size))
vdso = vdso_file->temp_file_name;
close(fd);
out:
free(buf);
vdso_file->found = (vdso != NULL);
vdso_file->error = !vdso_file->found;
return vdso;
}
void machine__exit_vdso(struct machine *machine)
{
struct vdso_info *vdso_info = machine->vdso_info;
if (!vdso_info)
return;
if (vdso_info->vdso.found)
unlink(vdso_info->vdso.temp_file_name);
#if BITS_PER_LONG == 64
if (vdso_info->vdso32.found)
unlink(vdso_info->vdso32.temp_file_name);
if (vdso_info->vdsox32.found)
unlink(vdso_info->vdsox32.temp_file_name);
#endif
zfree(&machine->vdso_info);
}
static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
const char *long_name)
{
struct dso *dso;
dso = dso__new(short_name);
if (dso != NULL) {
__dsos__add(&machine->dsos, dso);
dso__set_long_name(dso, long_name, false);
}
return dso;
}
#if BITS_PER_LONG == 64
static enum dso_type machine__thread_dso_type(struct machine *machine,
struct thread *thread)
{
enum dso_type dso_type = DSO__TYPE_UNKNOWN;
struct map *map;
struct dso *dso;
map = map_groups__first(thread->mg, MAP__FUNCTION);
for (; map ; map = map_groups__next(map)) {
dso = map->dso;
if (!dso || dso->long_name[0] != '/')
continue;
dso_type = dso__type(dso, machine);
if (dso_type != DSO__TYPE_UNKNOWN)
break;
}
return dso_type;
}
static int vdso__do_copy_compat(FILE *f, int fd)
{
char buf[4096];
size_t count;
while (1) {
count = fread(buf, 1, sizeof(buf), f);
if (ferror(f))
return -errno;
if (feof(f))
break;
if (count && writen(fd, buf, count) != (ssize_t)count)
return -errno;
}
return 0;
}
static int vdso__copy_compat(const char *prog, int fd)
{
FILE *f;
int err;
f = popen(prog, "r");
if (!f)
return -errno;
err = vdso__do_copy_compat(f, fd);
if (pclose(f) == -1)
return -errno;
return err;
}
static int vdso__create_compat_file(const char *prog, char *temp_name)
{
int fd, err;
fd = mkstemp(temp_name);
if (fd < 0)
return -errno;
err = vdso__copy_compat(prog, fd);
if (close(fd) == -1)
return -errno;
return err;
}
static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
{
int err;
if (vdso_file->found)
return vdso_file->temp_file_name;
if (vdso_file->error)
return NULL;
err = vdso__create_compat_file(vdso_file->read_prog,
vdso_file->temp_file_name);
if (err) {
pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
vdso_file->error = true;
return NULL;
}
vdso_file->found = true;
return vdso_file->temp_file_name;
}
static struct dso *__machine__findnew_compat(struct machine *machine,
struct vdso_file *vdso_file)
{
const char *file_name;
struct dso *dso;
pthread_rwlock_wrlock(&machine->dsos.lock);
dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
if (dso)
goto out_unlock;
file_name = vdso__get_compat_file(vdso_file);
if (!file_name)
goto out_unlock;
dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
out_unlock:
pthread_rwlock_unlock(&machine->dsos.lock);
return dso;
}
static int __machine__findnew_vdso_compat(struct machine *machine,
struct thread *thread,
struct vdso_info *vdso_info,
struct dso **dso)
{
enum dso_type dso_type;
dso_type = machine__thread_dso_type(machine, thread);
#ifndef HAVE_PERF_READ_VDSO32
if (dso_type == DSO__TYPE_32BIT)
return 0;
#endif
#ifndef HAVE_PERF_READ_VDSOX32
if (dso_type == DSO__TYPE_X32BIT)
return 0;
#endif
switch (dso_type) {
case DSO__TYPE_32BIT:
*dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
return 1;
case DSO__TYPE_X32BIT:
*dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
return 1;
case DSO__TYPE_UNKNOWN:
case DSO__TYPE_64BIT:
default:
return 0;
}
}
#endif
struct dso *machine__findnew_vdso(struct machine *machine,
struct thread *thread __maybe_unused)
{
struct vdso_info *vdso_info;
struct dso *dso = NULL;
pthread_rwlock_wrlock(&machine->dsos.lock);
if (!machine->vdso_info)
machine->vdso_info = vdso_info__new();
vdso_info = machine->vdso_info;
if (!vdso_info)
goto out_unlock;
#if BITS_PER_LONG == 64
if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
goto out_unlock;
#endif
dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
if (!dso) {
char *file;
file = get_file(&vdso_info->vdso);
if (file)
dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
}
out_unlock:
dso__get(dso);
pthread_rwlock_unlock(&machine->dsos.lock);
return dso;
}
bool dso__is_vdso(struct dso *dso)
{
return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
!strcmp(dso->short_name, DSO__NAME_VDSO32) ||
!strcmp(dso->short_name, DSO__NAME_VDSOX32);
}