| Message ID | 90f81508ecc57bc0da318e0fe0f45cfe49b17ea7.1600417359.git.Tony.Ambardar@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | fix BTF usage on embedded systems | expand |
Tony Ambardar wrote: > Code in btf__parse_raw() fails to detect raw BTF of non-native endianness > and assumes it must be ELF data, which then fails to parse as ELF and > yields a misleading error message: > > root:/# bpftool btf dump file /sys/kernel/btf/vmlinux > libbpf: failed to get EHDR from /sys/kernel/btf/vmlinux > > For example, this could occur after cross-compiling a BTF-enabled kernel > for a target with non-native endianness, which is currently unsupported. > > Check for correct endianness and emit a clearer error message: > > root:/# bpftool btf dump file /sys/kernel/btf/vmlinux > libbpf: non-native BTF endianness is not supported > > Fixes: 94a1fedd63ed ("libbpf: Add btf__parse_raw() and generic btf__parse() APIs") > > Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> > --- > tools/lib/bpf/btf.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > index 7dfca7016aaa..6bdbc389b493 100644 > --- a/tools/lib/bpf/btf.c > +++ b/tools/lib/bpf/btf.c > @@ -659,6 +659,12 @@ struct btf *btf__parse_raw(const char *path) > err = -EIO; > goto err_out; > } > + if (magic == __bswap_16(BTF_MAGIC)) { > + /* non-native endian raw BTF */ > + pr_warn("non-native BTF endianness is not supported\n"); > + err = -LIBBPF_ERRNO__ENDIAN; > + goto err_out; > + } > if (magic != BTF_MAGIC) { > /* definitely not a raw BTF */ > err = -EPROTO; > -- > 2.25.1 > Acked-by: John Fastabend <john.fastabend@gmail.com>
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 7dfca7016aaa..6bdbc389b493 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -659,6 +659,12 @@ struct btf *btf__parse_raw(const char *path) err = -EIO; goto err_out; } + if (magic == __bswap_16(BTF_MAGIC)) { + /* non-native endian raw BTF */ + pr_warn("non-native BTF endianness is not supported\n"); + err = -LIBBPF_ERRNO__ENDIAN; + goto err_out; + } if (magic != BTF_MAGIC) { /* definitely not a raw BTF */ err = -EPROTO;
Code in btf__parse_raw() fails to detect raw BTF of non-native endianness and assumes it must be ELF data, which then fails to parse as ELF and yields a misleading error message: root:/# bpftool btf dump file /sys/kernel/btf/vmlinux libbpf: failed to get EHDR from /sys/kernel/btf/vmlinux For example, this could occur after cross-compiling a BTF-enabled kernel for a target with non-native endianness, which is currently unsupported. Check for correct endianness and emit a clearer error message: root:/# bpftool btf dump file /sys/kernel/btf/vmlinux libbpf: non-native BTF endianness is not supported Fixes: 94a1fedd63ed ("libbpf: Add btf__parse_raw() and generic btf__parse() APIs") Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> --- tools/lib/bpf/btf.c | 6 ++++++ 1 file changed, 6 insertions(+)