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libbpf: Add OPTS-based bpf_btf_load() API

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Similar to previous bpf_prog_load() and bpf_map_create() APIs, add
bpf_btf_load() API which is taking optional OPTS struct. Schedule
bpf_load_btf() for deprecation in v0.8 ([0]).

This makes naming consistent with BPF_BTF_LOAD command, sets up an API
for extensibility in the future, moves options parameters (log-related
fields) into optional options, and also allows to pass log_level
directly.

It also removes log buffer auto-allocation logic from low-level API
(consistent with bpf_prog_load() behavior), but preserves a special
treatment of log_level == 0 with non-NULL log_buf, which matches
low-level bpf_prog_load() and high-level libbpf APIs for BTF and program
loading behaviors.

  [0] Closes: https://github.com/libbpf/libbpf/issues/419

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-3-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko
2021-12-09 11:38:30 -08:00
committed by Andrii Nakryiko
parent 896a3ae0d0
commit 3c93f7ddb2
4 changed files with 69 additions and 12 deletions
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59
src/bpf.c
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@@ -1047,24 +1047,65 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd)
return libbpf_err_errno(fd);
}
int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
bool do_log)
int bpf_btf_load(const void *btf_data, size_t btf_size, const struct bpf_btf_load_opts *opts)
{
union bpf_attr attr = {};
const size_t attr_sz = offsetofend(union bpf_attr, btf_log_level);
union bpf_attr attr;
char *log_buf;
size_t log_size;
__u32 log_level;
int fd;
attr.btf = ptr_to_u64(btf);
memset(&attr, 0, attr_sz);
if (!OPTS_VALID(opts, bpf_btf_load_opts))
return libbpf_err(-EINVAL);
log_buf = OPTS_GET(opts, log_buf, NULL);
log_size = OPTS_GET(opts, log_size, 0);
log_level = OPTS_GET(opts, log_level, 0);
if (log_size > UINT_MAX)
return libbpf_err(-EINVAL);
if (log_size && !log_buf)
return libbpf_err(-EINVAL);
attr.btf = ptr_to_u64(btf_data);
attr.btf_size = btf_size;
/* log_level == 0 and log_buf != NULL means "try loading without
* log_buf, but retry with log_buf and log_level=1 on error", which is
* consistent across low-level and high-level BTF and program loading
* APIs within libbpf and provides a sensible behavior in practice
*/
if (log_level) {
attr.btf_log_buf = ptr_to_u64(log_buf);
attr.btf_log_size = (__u32)log_size;
attr.btf_log_level = log_level;
}
fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
if (fd < 0 && log_buf && log_level == 0) {
attr.btf_log_buf = ptr_to_u64(log_buf);
attr.btf_log_size = (__u32)log_size;
attr.btf_log_level = 1;
fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
}
return libbpf_err_errno(fd);
}
int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size, bool do_log)
{
LIBBPF_OPTS(bpf_btf_load_opts, opts);
int fd;
retry:
if (do_log && log_buf && log_buf_size) {
attr.btf_log_level = 1;
attr.btf_log_size = log_buf_size;
attr.btf_log_buf = ptr_to_u64(log_buf);
opts.log_buf = log_buf;
opts.log_size = log_buf_size;
opts.log_level = 1;
}
fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, sizeof(attr));
fd = bpf_btf_load(btf, btf_size, &opts);
if (fd < 0 && !do_log && log_buf && log_buf_size) {
do_log = true;
goto retry;