6.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Artem Savkov asavkov@redhat.com
[ Upstream commit a51cd6bf8e10793103c5870ff9e4db295a843604 ]
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@redhat.com Tested-by: Puranjay Mohan puranjay12@gmail.com Acked-by: Puranjay Mohan puranjay12@gmail.com Acked-by: Xu Kuohai xukuohai@huawei.com Message-ID: 20240321081809.158803-1-asavkov@redhat.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 582c4c2491edc..00217d8d034b7 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -876,7 +876,7 @@ 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: