diff options
| author | Ian Rogers <irogers@google.com> | 2024-01-25 15:18:40 -0800 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-01-29 16:42:42 -0800 |
| commit | f2e4040c82d3fddd11fa7c64e8f810e6f9cb7460 (patch) | |
| tree | f413ae5bdb8800f9612a875e827cc811bd3639b9 /tools/lib/bpf/btf.c | |
| parent | aecaa3ed48c3ae74c06f5e8ef0746b69c62397f1 (diff) | |
libbpf: Add some details for BTF parsing failures
As CONFIG_DEBUG_INFO_BTF is default off the existing "failed to find
valid kernel BTF" message makes diagnosing the kernel build issue somewhat
cryptic. Add a little more detail with the hope of helping users.
Before:
```
libbpf: failed to find valid kernel BTF
libbpf: Error loading vmlinux BTF: -3
```
After not accessible:
```
libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled?
libbpf: failed to find valid kernel BTF
libbpf: Error loading vmlinux BTF: -3
```
After not readable:
```
libbpf: failed to read kernel BTF from (/sys/kernel/btf/vmlinux): -1
```
Closes: https://lore.kernel.org/bpf/CAP-5=fU+DN_+Y=Y4gtELUsJxKNDDCOvJzPHvjUVaUoeFAzNnig@mail.gmail.com/
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240125231840.1647951-1-irogers@google.com
Diffstat (limited to 'tools/lib/bpf/btf.c')
| -rw-r--r-- | tools/lib/bpf/btf.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index ec92b87cae01..95db88b36cf3 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -4932,10 +4932,9 @@ static int btf_dedup_remap_types(struct btf_dedup *d) */ struct btf *btf__load_vmlinux_btf(void) { + const char *sysfs_btf_path = "/sys/kernel/btf/vmlinux"; + /* fall back locations, trying to find vmlinux on disk */ const char *locations[] = { - /* try canonical vmlinux BTF through sysfs first */ - "/sys/kernel/btf/vmlinux", - /* fall back to trying to find vmlinux on disk otherwise */ "/boot/vmlinux-%1$s", "/lib/modules/%1$s/vmlinux-%1$s", "/lib/modules/%1$s/build/vmlinux", @@ -4949,8 +4948,23 @@ struct btf *btf__load_vmlinux_btf(void) struct btf *btf; int i, err; - uname(&buf); + /* is canonical sysfs location accessible? */ + if (faccessat(AT_FDCWD, sysfs_btf_path, F_OK, AT_EACCESS) < 0) { + pr_warn("kernel BTF is missing at '%s', was CONFIG_DEBUG_INFO_BTF enabled?\n", + sysfs_btf_path); + } else { + btf = btf__parse(sysfs_btf_path, NULL); + if (!btf) { + err = -errno; + pr_warn("failed to read kernel BTF from '%s': %d\n", sysfs_btf_path, err); + return libbpf_err_ptr(err); + } + pr_debug("loaded kernel BTF from '%s'\n", path); + return btf; + } + /* try fallback locations */ + uname(&buf); for (i = 0; i < ARRAY_SIZE(locations); i++) { snprintf(path, PATH_MAX, locations[i], buf.release); |