From: Xu Kuohai <xukuohai@huaweicloud.com>
To: Artem Savkov <asavkov@redhat.com>, Xi Wang <xi.wang@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, netdev@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org,
Puranjay Mohan <puranjay12@gmail.com>
Subject: Re: [PATCH bpf-next v2] arm64: bpf: fix 32bit unconditional bswap
Date: Thu, 21 Mar 2024 16:32:48 +0800 [thread overview]
Message-ID: <dec82e88-6961-4bf6-92b7-9acc753aaad4@huaweicloud.com> (raw)
In-Reply-To: <20240321081809.158803-1-asavkov@redhat.com>
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@redhat.com>
> Tested-by: Puranjay Mohan <puranjay12@gmail.com>
> Acked-by: Puranjay Mohan <puranjay12@gmail.com>
> ---
> 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@huawei.com>
next prev parent reply other threads:[~2024-03-21 8:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-13 14:02 [PATCH bpf-next] arm64: bpf: zero upper bits after rev32 Artem Savkov
2024-03-20 5:59 ` Alexei Starovoitov
2024-03-20 11:34 ` Xu Kuohai
2024-03-20 13:38 ` Artem Savkov
2024-03-20 15:46 ` Puranjay Mohan
2024-03-20 16:15 ` Xi Wang
2024-03-21 2:00 ` Xu Kuohai
2024-03-21 8:18 ` [PATCH bpf-next v2] arm64: bpf: fix 32bit unconditional bswap Artem Savkov
2024-03-21 8:32 ` Xu Kuohai [this message]
2024-03-21 11:00 ` patchwork-bot+netdevbpf
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