[PATCH 5.15 522/917] libbpf: Fix endianness detection in BPF_CORE_READ_BITFIELD_PROBED()

Greg Kroah-Hartman
2021-11-15T23:44:18Z

From: Ilya Leoshkevich <iii@linux.ibm.com>

[ Upstream commit 45f2bebc8079788f62f22d9e8b2819afb1789d7b ]

__BYTE_ORDER is supposed to be defined by a libc, and __BYTE_ORDER__ -
by a compiler. bpf_core_read.h checks __BYTE_ORDER == __LITTLE_ENDIAN,
which is true if neither are defined, leading to incorrect behavior on
big-endian hosts if libc headers are not included, which is often the
case.

Fixes: ee26dade0e3b ("libbpf: Add support for relocatable bitfields")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211026010831.748682-2-iii@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/bpf_core_read.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 09ebe3db5f2f8..e4aa9996a5501 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -40,7 +40,7 @@ enum bpf_enum_value_kind {
#define __CORE_RELO(src, field, info) \
__builtin_preserve_field_info((src)->field, BPF_FIELD_##info)

-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \
bpf_probe_read_kernel( \
(void *)dst, \
--
2.33.0