1 files changed, 30 insertions, 11 deletions

diff --git a/tools/testing/selftests/bpf/bpf_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index 19d0604f8694..487cbfb89beb 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -1,23 +1,42 @@
 #ifndef __BPF_ENDIAN__
 #define __BPF_ENDIAN__
 
-#include <asm/byteorder.h>
+#include <linux/swab.h>
 
-#if __BYTE_ORDER == __LITTLE_ENDIAN
-# define __bpf_ntohs(x)         __builtin_bswap16(x)
-# define __bpf_htons(x)         __builtin_bswap16(x)
-#elif __BYTE_ORDER == __BIG_ENDIAN
-# define __bpf_ntohs(x)         (x)
-# define __bpf_htons(x)         (x)
+/* LLVM's BPF target selects the endianness of the CPU
+ * it compiles on, or the user specifies (bpfel/bpfeb),
+ * respectively. The used __BYTE_ORDER__ is defined by
+ * the compiler, we cannot rely on __BYTE_ORDER from
+ * libc headers, since it doesn't reflect the actual
+ * requested byte order.
+ *
+ * Note, LLVM's BPF target has different __builtin_bswapX()
+ * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
+ * in bpfel and bpfeb case, which means below, that we map
+ * to cpu_to_be16(). We could use it unconditionally in BPF
+ * case, but better not rely on it, so that this header here
+ * can be used from application and BPF program side, which
+ * use different targets.
+ */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+# define __bpf_ntohs(x)                 __builtin_bswap16(x)
+# define __bpf_htons(x)                 __builtin_bswap16(x)
+# define __bpf_constant_ntohs(x)        ___constant_swab16(x)
+# define __bpf_constant_htons(x)        ___constant_swab16(x)
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+# define __bpf_ntohs(x)                 (x)
+# define __bpf_htons(x)                 (x)
+# define __bpf_constant_ntohs(x)        (x)
+# define __bpf_constant_htons(x)        (x)
 #else
-# error "Fix your __BYTE_ORDER?!"
+# error "Fix your compiler's __BYTE_ORDER__?!"
 #endif
 
 #define bpf_htons(x)                            \
         (__builtin_constant_p(x) ?              \
-         __constant_htons(x) : __bpf_htons(x))
+         __bpf_constant_htons(x) : __bpf_htons(x))
 #define bpf_ntohs(x)                            \
         (__builtin_constant_p(x) ?              \
-         __constant_ntohs(x) : __bpf_ntohs(x))
+         __bpf_constant_ntohs(x) : __bpf_ntohs(x))
 
-#endif
+#endif /* __BPF_ENDIAN__ */