From: Yonghong Song <yhs@meta.com>
To: Eduard Zingerman <eddyz87@gmail.com>, Yonghong Song <yhs@fb.com>,
bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Fangrui Song <maskray@google.com>,
kernel-team@fb.com
Subject: Re: [PATCH bpf-next v2 05/15] bpf: Support new signed div/mod instructions.
Date: Tue, 18 Jul 2023 19:30:43 -0700 [thread overview]
Message-ID: <5cdd79d3-d4c7-b119-ebcb-b8b143c79a01@meta.com> (raw)
In-Reply-To: <b8a16850c0482bf64f30b41c7dcb8b33ea6a6f61.camel@gmail.com>
On 7/18/23 4:00 PM, Eduard Zingerman wrote:
> On Wed, 2023-07-12 at 23:07 -0700, Yonghong Song wrote:
>> Add interpreter/jit support for new signed div/mod insns.
>> The new signed div/mod instructions are encoded with
>> unsigned div/mod instructions plus insn->off == 1.
>> Also add basic verifier support to ensure new insns get
>> accepted.
>>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>> arch/x86/net/bpf_jit_comp.c | 27 +++++++----
>> kernel/bpf/core.c | 96 ++++++++++++++++++++++++++++++-------
>> kernel/bpf/verifier.c | 6 ++-
>> 3 files changed, 103 insertions(+), 26 deletions(-)
>>
>> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
>> index adda5e7626b4..3176b60d25c7 100644
>> --- a/arch/x86/net/bpf_jit_comp.c
>> +++ b/arch/x86/net/bpf_jit_comp.c
>> @@ -1194,15 +1194,26 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
>> /* mov rax, dst_reg */
>> emit_mov_reg(&prog, is64, BPF_REG_0, dst_reg);
>>
>> - /*
>> - * xor edx, edx
>> - * equivalent to 'xor rdx, rdx', but one byte less
>> - */
>> - EMIT2(0x31, 0xd2);
>> + if (insn->off == 0) {
>> + /*
>> + * xor edx, edx
>> + * equivalent to 'xor rdx, rdx', but one byte less
>> + */
>> + EMIT2(0x31, 0xd2);
>>
>> - /* div src_reg */
>> - maybe_emit_1mod(&prog, src_reg, is64);
>> - EMIT2(0xF7, add_1reg(0xF0, src_reg));
>> + /* div src_reg */
>> + maybe_emit_1mod(&prog, src_reg, is64);
>> + EMIT2(0xF7, add_1reg(0xF0, src_reg));
>> + } else {
>> + if (BPF_CLASS(insn->code) == BPF_ALU)
>> + EMIT1(0x99); /* cltd */
>> + else
>> + EMIT2(0x48, 0x99); /* cqto */
>
> Nitpick: I can't find names cltd/cqto in the Intel instruction manual,
> instead it uses names cdq/cqo for these instructions.
> (See Vol. 2A pages 3-315 and 3-497)
I got these asm names from
https://defuse.ca/online-x86-assembler.htm
I will check the Intel insn manual and make the change
accordingly.
>
>> +
>> + /* idiv src_reg */
>> + maybe_emit_1mod(&prog, src_reg, is64);
>> + EMIT2(0xF7, add_1reg(0xF8, src_reg));
>> + }
>>
>> if (BPF_OP(insn->code) == BPF_MOD &&
>> dst_reg != BPF_REG_3)
[...]
next prev parent reply other threads:[~2023-07-19 2:31 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-13 6:07 [PATCH bpf-next v2 00/15] bpf: Support new insns from cpu v4 Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 01/15] bpf: Support new sign-extension load insns Yonghong Song
2023-07-14 18:13 ` Alexei Starovoitov
2023-07-14 23:22 ` Yonghong Song
2023-07-17 1:39 ` Eduard Zingerman
2023-07-19 0:15 ` Eduard Zingerman
2023-07-19 2:28 ` Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 02/15] bpf: Fix sign-extension ctx member accesses Yonghong Song
2023-07-17 1:40 ` Eduard Zingerman
2023-07-19 0:40 ` Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 03/15] bpf: Support new sign-extension mov insns Yonghong Song
2023-07-17 1:41 ` Eduard Zingerman
2023-07-19 1:17 ` Yonghong Song
2023-07-19 12:53 ` Eduard Zingerman
2023-07-19 15:59 ` Fangrui Song
2023-07-19 16:57 ` Eduard Zingerman
2023-07-13 6:07 ` [PATCH bpf-next v2 04/15] bpf: Support new unconditional bswap instruction Yonghong Song
2023-07-17 1:42 ` Eduard Zingerman
2023-07-19 1:22 ` Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 05/15] bpf: Support new signed div/mod instructions Yonghong Song
2023-07-18 23:00 ` Eduard Zingerman
2023-07-19 2:30 ` Yonghong Song [this message]
2023-07-19 2:44 ` Alexei Starovoitov
2023-07-19 6:57 ` Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 06/15] bpf: Fix jit blinding with new sdiv/smov insns Yonghong Song
2023-07-13 6:07 ` [PATCH bpf-next v2 07/15] bpf: Support new 32bit offset jmp instruction Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 08/15] selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing Yonghong Song
2023-07-13 6:18 ` Fangrui Song
2023-07-13 6:25 ` Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 09/15] selftests/bpf: Add unit tests for new sign-extension load insns Yonghong Song
2023-07-18 23:06 ` Eduard Zingerman
2023-07-13 6:08 ` [PATCH bpf-next v2 10/15] selftests/bpf: Add unit tests for new sign-extension mov insns Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 11/15] selftests/bpf: Add unit tests for new bswap insns Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 12/15] selftests/bpf: Add unit tests for new sdiv/smod insns Yonghong Song
2023-07-18 23:10 ` Eduard Zingerman
2023-07-13 6:08 ` [PATCH bpf-next v2 13/15] selftests/bpf: Add unit tests for new gotol insn Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 14/15] selftests/bpf: Test ldsx with more complex cases Yonghong Song
2023-07-13 6:08 ` [PATCH bpf-next v2 15/15] docs/bpf: Add documentation for new instructions Yonghong Song
2023-07-14 18:28 ` Alexei Starovoitov
2023-07-14 23:26 ` Yonghong Song
2023-07-14 23:33 ` Dave Thaler
2023-07-14 23:33 ` [Bpf] " Dave Thaler
2023-07-15 0:23 ` Alexei Starovoitov
2023-07-15 0:23 ` [Bpf] " Alexei Starovoitov
2023-07-14 23:34 ` Dave Thaler
2023-07-14 23:34 ` [Bpf] " Dave Thaler
2023-07-17 1:39 ` [PATCH bpf-next v2 00/15] bpf: Support new insns from cpu v4 Eduard Zingerman
2023-07-17 16:56 ` Alexei Starovoitov
2023-07-17 17:04 ` Eduard Zingerman
2023-07-17 21:52 ` Yonghong Song
2023-07-21 14:56 ` Jose E. Marchesi
2023-07-24 0:17 ` Jose E. Marchesi
2023-07-24 1:04 ` Jose E. Marchesi
2023-07-24 2:35 ` Yonghong Song
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