From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next 06/11] libbpf: add per-program log buffer setter and getter
Date: Sun, 5 Dec 2021 12:32:29 -0800 [thread overview]
Message-ID: <20211205203234.1322242-7-andrii@kernel.org> (raw)
In-Reply-To: <20211205203234.1322242-1-andrii@kernel.org>
Allow to set user-provided log buffer on a per-program basis ([0]). This
gives great deal of flexibility in terms of which programs are loaded
with logging enabled and where corresponding logs go.
Log buffer set with bpf_program__set_log_buf() overrides kernel_log_buf
and kernel_log_size settings set at bpf_object open time through
bpf_object_open_opts, if any.
Adjust bpf_object_load_prog_instance() logic to not perform own log buf
allocation and load retry if custom log buffer is provided by the user.
[0] Closes: https://github.com/libbpf/libbpf/issues/418
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf.c | 86 ++++++++++++++++++++++++++++++++--------
tools/lib/bpf/libbpf.h | 7 ++++
tools/lib/bpf/libbpf.map | 2 +
3 files changed, 78 insertions(+), 17 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3fd4e3d5a11f..00807bf8719f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -331,7 +331,11 @@ struct bpf_program {
struct reloc_desc *reloc_desc;
int nr_reloc;
- int log_level;
+
+ /* BPF verifier log settings */
+ char *log_buf;
+ size_t log_size;
+ __u32 log_level;
struct {
int nr;
@@ -713,6 +717,9 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
prog->instances.fds = NULL;
prog->instances.nr = -1;
+ /* inherit object's log_level */
+ prog->log_level = obj->log_level;
+
prog->sec_name = strdup(sec_name);
if (!prog->sec_name)
goto errout;
@@ -6591,8 +6598,10 @@ static int bpf_object_load_prog_instance(struct bpf_object *obj, struct bpf_prog
const char *prog_name = NULL;
char *cp, errmsg[STRERR_BUFSIZE];
size_t log_buf_size = 0;
- char *log_buf = NULL;
+ char *log_buf = NULL, *tmp;
int btf_fd, ret, err;
+ bool own_log_buf = true;
+ __u32 log_level = prog->log_level;
if (prog->type == BPF_PROG_TYPE_UNSPEC) {
/*
@@ -6627,7 +6636,7 @@ static int bpf_object_load_prog_instance(struct bpf_object *obj, struct bpf_prog
load_attr.line_info_rec_size = prog->line_info_rec_size;
load_attr.line_info_cnt = prog->line_info_cnt;
}
- load_attr.log_level = prog->log_level;
+ load_attr.log_level = log_level;
load_attr.prog_flags = prog->prog_flags;
load_attr.fd_array = obj->fd_array;
@@ -6648,21 +6657,42 @@ static int bpf_object_load_prog_instance(struct bpf_object *obj, struct bpf_prog
*prog_fd = -1;
return 0;
}
-retry_load:
- if (log_buf_size) {
- log_buf = malloc(log_buf_size);
- if (!log_buf)
- return -ENOMEM;
- *log_buf = 0;
+retry_load:
+ /* if log_level is zero, we don't request logs initiallly even if
+ * custom log_buf is specified; if the program load fails, then we'll
+ * bump log_level to 1 and use either custom log_buf or we'll allocate
+ * our own and retry the load to get details on what failed
+ */
+ if (log_level) {
+ if (prog->log_buf) {
+ log_buf = prog->log_buf;
+ log_buf_size = prog->log_size;
+ own_log_buf = false;
+ } else if (obj->log_buf) {
+ log_buf = obj->log_buf;
+ log_buf_size = obj->log_size;
+ own_log_buf = false;
+ } else {
+ log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size * 2);
+ tmp = realloc(log_buf, log_buf_size);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ log_buf = tmp;
+ log_buf[0] = '\0';
+ own_log_buf = true;
+ }
}
load_attr.log_buf = log_buf;
load_attr.log_size = log_buf_size;
- ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
+ load_attr.log_level = log_level;
+ ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
if (ret >= 0) {
- if (log_buf && load_attr.log_level) {
+ if (log_level && own_log_buf) {
pr_debug("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
prog->name, log_buf);
}
@@ -6690,19 +6720,20 @@ static int bpf_object_load_prog_instance(struct bpf_object *obj, struct bpf_prog
goto out;
}
- if (!log_buf || errno == ENOSPC) {
- log_buf_size = max((size_t)BPF_LOG_BUF_SIZE,
- log_buf_size << 1);
- free(log_buf);
+ if (log_level == 0) {
+ log_level = 1;
goto retry_load;
}
+ /* on ENOSPC, increase log buffer size, unless custom log_buf is specified */
+ if (own_log_buf && errno == ENOSPC && log_buf_size < UINT_MAX / 2)
+ goto retry_load;
ret = -errno;
cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
pr_warn("prog '%s': BPF program load failed: %s\n", prog->name, cp);
pr_perm_msg(ret);
- if (log_buf && log_buf[0] != '\0') {
+ if (own_log_buf && log_buf && log_buf[0] != '\0') {
pr_warn("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
prog->name, log_buf);
}
@@ -6712,7 +6743,8 @@ static int bpf_object_load_prog_instance(struct bpf_object *obj, struct bpf_prog
}
out:
- free(log_buf);
+ if (own_log_buf)
+ free(log_buf);
return ret;
}
@@ -8498,6 +8530,26 @@ int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
return 0;
}
+const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size)
+{
+ *log_size = prog->log_size;
+ return prog->log_buf;
+}
+
+int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size)
+{
+ if (log_size && !log_buf)
+ return -EINVAL;
+ if (prog->log_size > UINT_MAX)
+ return -EINVAL;
+ if (prog->obj->loaded)
+ return -EBUSY;
+
+ prog->log_buf = log_buf;
+ prog->log_size = log_size;
+ return 0;
+}
+
#define SEC_DEF(sec_pfx, ptype, atype, flags, ...) { \
.sec = sec_pfx, \
.prog_type = BPF_PROG_TYPE_##ptype, \
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index ae7cda7ad731..82fd61b674c5 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -538,8 +538,15 @@ bpf_program__set_expected_attach_type(struct bpf_program *prog,
LIBBPF_API __u32 bpf_program__flags(const struct bpf_program *prog);
LIBBPF_API int bpf_program__set_flags(struct bpf_program *prog, __u32 flags);
+
+/* Per-program log level and log buffer getters/setters.
+ * See bpf_object_open_opts comments regarding log_level and log_buf
+ * interactions.
+ */
LIBBPF_API __u32 bpf_program__log_level(const struct bpf_program *prog);
LIBBPF_API int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level);
+LIBBPF_API const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size);
+LIBBPF_API int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size);
LIBBPF_API int
bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 08cdfe840436..4d483af7dba6 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -423,6 +423,8 @@ LIBBPF_0.6.0 {
LIBBPF_0.7.0 {
global:
bpf_btf_load;
+ bpf_program__log_buf;
bpf_program__log_level;
+ bpf_program__set_log_buf;
bpf_program__set_log_level;
};
--
2.30.2
next prev parent reply other threads:[~2021-12-05 20:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-05 20:32 [PATCH bpf-next 00/11] Enhance and rework logging controls in libbpf Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 01/11] libbpf: add OPTS-based bpf_btf_load() API Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 02/11] libbpf: allow passing preallocated log_buf when loading BTF into kernel Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 03/11] libbpf: allow passing user log setting through bpf_object_open_opts Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 04/11] libbpf: improve logging around BPF program loading Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 05/11] libbpf: preserve kernel error code and remove kprobe prog type guessing Andrii Nakryiko
2021-12-05 20:32 ` Andrii Nakryiko [this message]
2021-12-07 19:41 ` [PATCH bpf-next 06/11] libbpf: add per-program log buffer setter and getter Alexei Starovoitov
2021-12-07 22:48 ` Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 07/11] libbpf: deprecate bpf_object__load_xattr() Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 08/11] selftests/bpf: replace all uses of bpf_load_btf() with bpf_btf_load() Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 09/11] selftests/bpf: add test for libbpf's custom log_buf behavior Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 10/11] selftests/bpf: remove the only use of deprecated bpf_object__load_xattr() Andrii Nakryiko
2021-12-05 20:32 ` [PATCH bpf-next 11/11] bpftool: switch bpf_object__load_xattr() to bpf_object__load() Andrii Nakryiko
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