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    SubjectRe: [PATCH RFC v2 bpf-next 7/9] selftests/bpf: Replace extract_build_id with read_build_id
    On Tue, Feb 28, 2023 at 1:33 AM Jiri Olsa <jolsa@kernel.org> wrote:
    >
    > 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>
    > ---

    small nit below, but looks good. Thanks for clean up!

    Acked-by: Andrii Nakryiko <andrii@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);

    nit: "urandom_read" vs "./urandom_read" matters only when executing
    binary, not when opening a file. So all these "./" just creates
    unnecessary confusion, IMO

    > + 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
    >

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