On Fri, Jan 26, 2024 at 02:09:44PM -0800, Andrii Nakryiko wrote: > Android implementation of libc errors out with -EINVAL in faccessat() if > passed AT_EACCESS ([0]), this leads to ridiculous issue with libbpf > refusing to load /sys/kernel/btf/vmlinux on Androids ([1]). Fix by > detecting Android and redefining AT_EACCESS to 0, it's equivalent on > Android. > > [0] https://android.googlesource.com/platform/bionic/+/refs/heads/android13-release/libc/bionic/faccessat.cpp#50 > [1] https://github.com/libbpf/libbpf-bootstrap/issues/250#issuecomment-1911324250 > > Fixes: 6a4ab8869d0b ("libbpf: Fix the case of running as non-root with capabilities") > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> jirka > --- > tools/lib/bpf/libbpf_internal.h | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h > index 930cc9616527..5b30f3b67a02 100644 > --- a/tools/lib/bpf/libbpf_internal.h > +++ b/tools/lib/bpf/libbpf_internal.h > @@ -19,6 +19,20 @@ > #include <libelf.h> > #include "relo_core.h" > > +/* Android's libc doesn't support AT_EACCESS in faccessat() implementation > + * ([0]), and just returns -EINVAL even if file exists and is accessible. > + * See [1] for issues caused by this. > + * > + * So just redefine it to 0 on Android. > + * > + * [0] https://android.googlesource.com/platform/bionic/+/refs/heads/android13-release/libc/bionic/faccessat.cpp#50 > + * [1] https://github.com/libbpf/libbpf-bootstrap/issues/250#issuecomment-1911324250 > + */ > +#ifdef __ANDROID__ > +#undef AT_EACCESS > +#define AT_EACCESS 0 > +#endif > + > /* make sure libbpf doesn't use kernel-only integer typedefs */ > #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64 > > -- > 2.34.1 > >
