On 3/21/2024 4:18 PM, Artem Savkov wrote:
In case when is64 == 1 in emit(A64_REV32(is64, dst, dst), ctx) the
generated insn reverses byte order for both high and low 32-bit words,
resuling in an incorrect swap as indicated by the jit test:
[ 9757.262607] test_bpf: #312 BSWAP 16: 0x0123456789abcdef -> 0xefcd jited:1 8 PASS
[ 9757.264435] test_bpf: #313 BSWAP 32: 0x0123456789abcdef -> 0xefcdab89 jited:1 ret 1460850314 != -271733879 (0x5712ce8a != 0xefcdab89)FAIL (1 times)
[ 9757.266260] test_bpf: #314 BSWAP 64: 0x0123456789abcdef -> 0x67452301 jited:1 8 PASS
[ 9757.268000] test_bpf: #315 BSWAP 64: 0x0123456789abcdef >> 32 -> 0xefcdab89 jited:1 8 PASS
[ 9757.269686] test_bpf: #316 BSWAP 16: 0xfedcba9876543210 -> 0x1032 jited:1 8 PASS
[ 9757.271380] test_bpf: #317 BSWAP 32: 0xfedcba9876543210 -> 0x10325476 jited:1 ret -1460850316 != 271733878 (0xa8ed3174 != 0x10325476)FAIL (1 times)
[ 9757.273022] test_bpf: #318 BSWAP 64: 0xfedcba9876543210 -> 0x98badcfe jited:1 7 PASS
[ 9757.274721] test_bpf: #319 BSWAP 64: 0xfedcba9876543210 >> 32 -> 0x10325476 jited:1 9 PASS
Fix this by forcing 32bit variant of rev32.
Fixes: 1104247f3f979 ("bpf, arm64: Support unconditional bswap")
Signed-off-by: Artem Savkov <asavkov@xxxxxxxxxx>
Tested-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
Acked-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
---
arch/arm64/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index c5b461dda4385..c3ededd23cbf6 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -943,7 +943,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit(A64_UXTH(is64, dst, dst), ctx);
break;
case 32:
- emit(A64_REV32(is64, dst, dst), ctx);
+ emit(A64_REV32(0, dst, dst), ctx);
/* upper 32 bits already cleared */
break;
case 64:
Acked-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
