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authorDave Martin <dave.martin@linaro.org>2010-07-30 09:08:08 -0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2010-07-30 09:53:30 -0300
commit21916c380d93ab59d6d07ee198fb31c8f1338e26 (patch)
tree8d7d491ea6549b74144efa5ba63c4240f84a874a /tools
parent6e406257b3794009e3b7a6d48b54beb547719565 (diff)
downloadlwn-21916c380d93ab59d6d07ee198fb31c8f1338e26.tar.gz
lwn-21916c380d93ab59d6d07ee198fb31c8f1338e26.zip
perf tools: Factor out buildid reading and make it implicit in dso__load
If we have a buildid, then we never want to load an image which has no buildid, or which has a different buildid, so it makes sense for the check to be built into dso__load and not done separately. This is fine for old distros which don't use buildid at all since we do no check in that case. This refactoring also alleviates some subtle race condition issues by not opening ELF images twice to check the buildid and then load the symbols, which could lead to weirdness if an image is replaced under our feet. Signed-off-by: Dave Martin <dave.martin@linaro.org> LKML-Reference: <new-submission> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/symbol.c80
1 files changed, 47 insertions, 33 deletions
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 242d2b216f46..b812ace91c60 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -26,6 +26,8 @@
#define NT_GNU_BUILD_ID 3
#endif
+static bool dso__build_id_equal(const struct dso *self, u8 *build_id);
+static int elf_read_build_id(Elf *elf, void *bf, size_t size);
static void dsos__add(struct list_head *head, struct dso *dso);
static struct map *map__new2(u64 start, struct dso *dso, enum map_type type);
static int dso__load_kernel_sym(struct dso *self, struct map *map,
@@ -993,6 +995,17 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
goto out_elf_end;
}
+ if (self->has_build_id) {
+ u8 build_id[BUILD_ID_SIZE];
+
+ if (elf_read_build_id(elf, build_id,
+ BUILD_ID_SIZE) != BUILD_ID_SIZE)
+ goto out_elf_end;
+
+ if (!dso__build_id_equal(self, build_id))
+ goto out_elf_end;
+ }
+
sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
if (sec == NULL) {
sec = elf_section_by_name(elf, &ehdr, &shdr, ".dynsym", NULL);
@@ -1193,37 +1206,26 @@ bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
*/
#define NOTE_ALIGN(n) (((n) + 3) & -4U)
-int filename__read_build_id(const char *filename, void *bf, size_t size)
+static int elf_read_build_id(Elf *elf, void *bf, size_t size)
{
- int fd, err = -1;
+ int err = -1;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *data;
Elf_Scn *sec;
Elf_Kind ek;
void *ptr;
- Elf *elf;
if (size < BUILD_ID_SIZE)
goto out;
- fd = open(filename, O_RDONLY);
- if (fd < 0)
- goto out;
-
- elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
- if (elf == NULL) {
- pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
- goto out_close;
- }
-
ek = elf_kind(elf);
if (ek != ELF_K_ELF)
- goto out_elf_end;
+ goto out;
if (gelf_getehdr(elf, &ehdr) == NULL) {
pr_err("%s: cannot get elf header.\n", __func__);
- goto out_elf_end;
+ goto out;
}
sec = elf_section_by_name(elf, &ehdr, &shdr,
@@ -1232,12 +1234,12 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
sec = elf_section_by_name(elf, &ehdr, &shdr,
".notes", NULL);
if (sec == NULL)
- goto out_elf_end;
+ goto out;
}
data = elf_getdata(sec, NULL);
if (data == NULL)
- goto out_elf_end;
+ goto out;
ptr = data->d_buf;
while (ptr < (data->d_buf + data->d_size)) {
@@ -1259,7 +1261,31 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
}
ptr += descsz;
}
-out_elf_end:
+
+out:
+ return err;
+}
+
+int filename__read_build_id(const char *filename, void *bf, size_t size)
+{
+ int fd, err = -1;
+ Elf *elf;
+
+ if (size < BUILD_ID_SIZE)
+ goto out;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ goto out;
+
+ elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+ if (elf == NULL) {
+ pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
+ goto out_close;
+ }
+
+ err = elf_read_build_id(elf, bf, size);
+
elf_end(elf);
out_close:
close(fd);
@@ -1335,7 +1361,6 @@ int dso__load(struct dso *self, struct map *map, symbol_filter_t filter)
{
int size = PATH_MAX;
char *name;
- u8 build_id[BUILD_ID_SIZE];
int ret = -1;
int fd;
struct machine *machine;
@@ -1382,16 +1407,14 @@ more:
self->long_name);
break;
case DSO__ORIG_BUILDID:
- if (filename__read_build_id(self->long_name, build_id,
- sizeof(build_id))) {
+ if (self->has_build_id) {
char build_id_hex[BUILD_ID_SIZE * 2 + 1];
- build_id__sprintf(build_id, sizeof(build_id),
+ build_id__sprintf(self->build_id,
+ sizeof(self->build_id),
build_id_hex);
snprintf(name, size,
"/usr/lib/debug/.build-id/%.2s/%s.debug",
build_id_hex, build_id_hex + 2);
- if (self->has_build_id)
- goto compare_build_id;
break;
}
self->origin++;
@@ -1410,15 +1433,6 @@ more:
default:
goto out;
}
-
- if (self->has_build_id) {
- if (filename__read_build_id(name, build_id,
- sizeof(build_id)) < 0)
- goto more;
-compare_build_id:
- if (!dso__build_id_equal(self, build_id))
- goto more;
- }
open_file:
fd = open(name, O_RDONLY);
} while (fd < 0);