* [PATCHv4 bpf-next 2/3] selftests/bpf: Add read_build_id function
2023-03-31 9:31 [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function Jiri Olsa
2023-03-31 9:31 ` [PATCHv4 bpf-next 1/3] selftests/bpf: Add err.h header Jiri Olsa
@ 2023-03-31 9:31 ` Jiri Olsa
2023-03-31 9:31 ` [PATCHv4 bpf-next 3/3] selftests/bpf: Replace extract_build_id with read_build_id Jiri Olsa
2023-03-31 16:50 ` [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Jiri Olsa @ 2023-03-31 9:31 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: bpf, Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo
Adding read_build_id function that parses out build id from
specified binary.
It will replace extract_build_id and also be used in following
changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/testing/selftests/bpf/trace_helpers.c | 82 +++++++++++++++++++++
tools/testing/selftests/bpf/trace_helpers.h | 5 ++
2 files changed, 87 insertions(+)
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 934bf28fc888..9b070cdf44ac 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -11,6 +11,9 @@
#include <linux/perf_event.h>
#include <sys/mman.h>
#include "trace_helpers.h"
+#include <linux/limits.h>
+#include <libelf.h>
+#include <gelf.h>
#define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe"
#define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe"
@@ -234,3 +237,82 @@ ssize_t get_rel_offset(uintptr_t addr)
fclose(f);
return -EINVAL;
}
+
+static int
+parse_build_id_buf(const void *note_start, Elf32_Word note_size, char *build_id)
+{
+ Elf32_Word note_offs = 0;
+
+ while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
+ Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
+
+ if (nhdr->n_type == 3 && nhdr->n_namesz == sizeof("GNU") &&
+ !strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 &&
+ nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
+ memcpy(build_id, note_start + note_offs +
+ ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), nhdr->n_descsz);
+ memset(build_id + nhdr->n_descsz, 0, BPF_BUILD_ID_SIZE - nhdr->n_descsz);
+ return (int) nhdr->n_descsz;
+ }
+
+ note_offs = note_offs + sizeof(Elf32_Nhdr) +
+ ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
+ }
+
+ return -ENOENT;
+}
+
+/* Reads binary from *path* file and returns it in the *build_id* buffer
+ * with *size* which is expected to be at least BPF_BUILD_ID_SIZE bytes.
+ * Returns size of build id on success. On error the error value is
+ * returned.
+ */
+int read_build_id(const char *path, char *build_id, size_t size)
+{
+ int fd, err = -EINVAL;
+ Elf *elf = NULL;
+ GElf_Ehdr ehdr;
+ size_t max, i;
+
+ if (size < BPF_BUILD_ID_SIZE)
+ return -EINVAL;
+
+ fd = open(path, O_RDONLY | O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ (void)elf_version(EV_CURRENT);
+
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf)
+ goto out;
+ if (elf_kind(elf) != ELF_K_ELF)
+ goto out;
+ if (!gelf_getehdr(elf, &ehdr))
+ goto out;
+
+ for (i = 0; i < ehdr.e_phnum; i++) {
+ GElf_Phdr mem, *phdr;
+ char *data;
+
+ phdr = gelf_getphdr(elf, i, &mem);
+ if (!phdr)
+ goto out;
+ if (phdr->p_type != PT_NOTE)
+ continue;
+ data = elf_rawfile(elf, &max);
+ if (!data)
+ goto out;
+ if (phdr->p_offset + phdr->p_memsz > max)
+ goto out;
+ err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id);
+ if (err > 0)
+ break;
+ }
+
+out:
+ if (elf)
+ elf_end(elf);
+ close(fd);
+ return err;
+}
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 53efde0e2998..876f3e711df6 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -4,6 +4,9 @@
#include <bpf/libbpf.h>
+#define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask))
+#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a)-1)
+
struct ksym {
long addr;
char *name;
@@ -23,4 +26,6 @@ void read_trace_pipe(void);
ssize_t get_uprobe_offset(const void *addr);
ssize_t get_rel_offset(uintptr_t addr);
+int read_build_id(const char *path, char *build_id, size_t size);
+
#endif
--
2.39.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCHv4 bpf-next 3/3] selftests/bpf: Replace extract_build_id with read_build_id
2023-03-31 9:31 [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function Jiri Olsa
2023-03-31 9:31 ` [PATCHv4 bpf-next 1/3] selftests/bpf: Add err.h header Jiri Olsa
2023-03-31 9:31 ` [PATCHv4 bpf-next 2/3] selftests/bpf: Add read_build_id function Jiri Olsa
@ 2023-03-31 9:31 ` Jiri Olsa
2023-03-31 16:50 ` [PATCHv4 bpf-next 0/3] selftests/bpf: Add read_build_id function patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Jiri Olsa @ 2023-03-31 9:31 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: bpf, Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo
Replacing extract_build_id with read_build_id that parses out
build id directly from elf without using readelf tool.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
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..b7ba5cd47d96 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, sizeof(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..47558b0d7f66 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, sizeof(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 d903e6a72a96..ea82921110da 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -629,31 +629,6 @@ 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 4b06b8347cd4..10ba43250668 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -405,7 +405,6 @@ 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
^ permalink raw reply related [flat|nested] 5+ messages in thread