[PATCH 1/3] arm: include: asm: swab: mask rev16 instruction for clang

Pavo Banicevic
2021-07-27T14:12:48Z

From: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>

The samples/bpf with clang -emit-llvm reuses linux headers to build
bpf samples, and this w/a only for samples (samples/bpf/Makefile
CLANG-bpf).

It allows to build samples/bpf for arm bpf using clang.
In another way clang -emit-llvm generates errors like:

CLANG-bpf samples/bpf/tc_l2_redirect_kern.o
<inline asm>:1:2: error: invalid register/token name
rev16 r3, r0

This decision is arguable, probably there is another way, but
it doesn't have impact on samples/bpf, so it's easier just ignore
it for clang, at least for now.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
---
arch/arm/include/asm/swab.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/arm/include/asm/swab.h b/arch/arm/include/asm/swab.h
index c6051823048b..a9fd9cd33d5e 100644
--- a/arch/arm/include/asm/swab.h
+++ b/arch/arm/include/asm/swab.h
@@ -25,8 +25,11 @@ static inline __attribute_const__ __u32 __arch_swahb32(__u32 x)
__asm__ ("rev16 %0, %1" : "=r" (x) : "r" (x));
return x;
}
+
+#ifndef __clang__
#define __arch_swahb32 __arch_swahb32
#define __arch_swab16(x) ((__u16)__arch_swahb32(x))
+#endif

static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
{
--
2.32.0