[PATCH RFC v2 bpf-next 7/9] selftests/bpf: Replace extract_build_id with read_build_id

Jiri Olsa
2023-02-28T09:34:05Z

Replacing extract_build_id with read_build_id that parses out
build id directly from elf without using readelf tool.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../bpf/prog_tests/stacktrace_build_id.c | 19 ++++++--------
.../bpf/prog_tests/stacktrace_build_id_nmi.c | 17 +++++--------
tools/testing/selftests/bpf/test_progs.c | 25 -------------------
tools/testing/selftests/bpf/test_progs.h | 1 -
4 files changed, 13 insertions(+), 49 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c
index 9ad09a6c538a..9e4b76ee356f 100644
--- a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c
+++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c
@@ -7,13 +7,12 @@ void test_stacktrace_build_id(void)

int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
struct test_stacktrace_build_id *skel;
- int err, stack_trace_len;
+ int err, stack_trace_len, build_id_size;
__u32 key, prev_key, val, duration = 0;
- char buf[256];
- int i, j;
+ char buf[BPF_BUILD_ID_SIZE];
struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
int build_id_matches = 0;
- int retry = 1;
+ int i, retry = 1;

retry:
skel = test_stacktrace_build_id__open_and_load();
@@ -52,9 +51,10 @@ void test_stacktrace_build_id(void)
"err %d errno %d\n", err, errno))
goto cleanup;

- err = extract_build_id(buf, 256);
+ build_id_size = read_build_id("./urandom_read", buf);
+ err = build_id_size < 0 ? build_id_size : 0;

- if (CHECK(err, "get build_id with readelf",
+ if (CHECK(err, "read_build_id",
"err %d errno %d\n", err, errno))
goto cleanup;

@@ -64,8 +64,6 @@ void test_stacktrace_build_id(void)
goto cleanup;

do {
- char build_id[64];
-
err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
if (CHECK(err, "lookup_elem from stackmap",
"err %d, errno %d\n", err, errno))
@@ -73,10 +71,7 @@ void test_stacktrace_build_id(void)
for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
id_offs[i].offset != 0) {
- for (j = 0; j < 20; ++j)
- sprintf(build_id + 2 * j, "%02x",
- id_offs[i].build_id[j] & 0xff);
- if (strstr(buf, build_id) != NULL)
+ if (memcmp(buf, id_offs[i].build_id, build_id_size) == 0)
build_id_matches = 1;
}
prev_key = key;
diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
index f4ea1a215ce4..8d84149ebcc7 100644
--- a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
+++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
@@ -28,11 +28,10 @@ void test_stacktrace_build_id_nmi(void)
.config = PERF_COUNT_HW_CPU_CYCLES,
};
__u32 key, prev_key, val, duration = 0;
- char buf[256];
- int i, j;
+ char buf[BPF_BUILD_ID_SIZE];
struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
- int build_id_matches = 0;
- int retry = 1;
+ int build_id_matches = 0, build_id_size;
+ int i, retry = 1;

attr.sample_freq = read_perf_max_sample_freq();

@@ -94,7 +93,8 @@ void test_stacktrace_build_id_nmi(void)
"err %d errno %d\n", err, errno))
goto cleanup;

- err = extract_build_id(buf, 256);
+ build_id_size = read_build_id("./urandom_read", buf);
+ err = build_id_size < 0 ? build_id_size : 0;

if (CHECK(err, "get build_id with readelf",
"err %d errno %d\n", err, errno))
@@ -106,8 +106,6 @@ void test_stacktrace_build_id_nmi(void)
goto cleanup;

do {
- char build_id[64];
-
err = bpf_map__lookup_elem(skel->maps.stackmap, &key, sizeof(key),
id_offs, sizeof(id_offs), 0);
if (CHECK(err, "lookup_elem from stackmap",
@@ -116,10 +114,7 @@ void test_stacktrace_build_id_nmi(void)
for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
id_offs[i].offset != 0) {
- for (j = 0; j < 20; ++j)
- sprintf(build_id + 2 * j, "%02x",
- id_offs[i].build_id[j] & 0xff);
- if (strstr(buf, build_id) != NULL)
+ if (memcmp(buf, id_offs[i].build_id, build_id_size) == 0)
build_id_matches = 1;
}
prev_key = key;
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 6d5e3022c75f..9813d53c4878 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -591,31 +591,6 @@ int compare_stack_ips(int smap_fd, int amap_fd, int stack_trace_len)
return err;
}

-int extract_build_id(char *build_id, size_t size)
-{
- FILE *fp;
- char *line = NULL;
- size_t len = 0;
-
- fp = popen("readelf -n ./urandom_read | grep 'Build ID'", "r");
- if (fp == NULL)
- return -1;
-
- if (getline(&line, &len, fp) == -1)
- goto err;
- pclose(fp);
-
- if (len > size)
- len = size;
- memcpy(build_id, line, len);
- build_id[len] = '\0';
- free(line);
- return 0;
-err:
- pclose(fp);
- return -1;
-}
-
static int finit_module(int fd, const char *param_values, int flags)
{
return syscall(__NR_finit_module, fd, param_values, flags);
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 9fbdc57c5b57..3825c2797a4b 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -404,7 +404,6 @@ static inline void *u64_to_ptr(__u64 ptr)
int bpf_find_map(const char *test, struct bpf_object *obj, const char *name);
int compare_map_keys(int map1_fd, int map2_fd);
int compare_stack_ips(int smap_fd, int amap_fd, int stack_trace_len);
-int extract_build_id(char *build_id, size_t size);
int kern_sync_rcu(void);
int trigger_module_test_read(int read_sz);
int trigger_module_test_write(int write_sz);
--
2.39.2