* [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
@ 2022-01-27 8:32 Hou Tao
2022-01-27 10:48 ` Brendan Jackman
2022-01-27 21:50 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 5+ messages in thread
From: Hou Tao @ 2022-01-27 8:32 UTC (permalink / raw)
To: Alexei Starovoitov, John Fastabend
Cc: Martin KaFai Lau, Yonghong Song, Daniel Borkmann,
Andrii Nakryiko, David S . Miller, Jakub Kicinski,
Brendan Jackman, netdev, bpf, houtao1
According to the LLVM commit (https://reviews.llvm.org/D72184),
sync_fetch_and_sub() is implemented as a negation followed by
sync_fetch_and_add(), so there will be no BPF_SUB op and just
remove it.
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
arch/x86/net/bpf_jit_comp.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index ce1f86f245c9..5d643ebb1e56 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -787,7 +787,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
/* emit opcode */
switch (atomic_op) {
case BPF_ADD:
- case BPF_SUB:
case BPF_AND:
case BPF_OR:
case BPF_XOR:
--
2.29.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
2022-01-27 8:32 [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op Hou Tao
@ 2022-01-27 10:48 ` Brendan Jackman
2022-01-27 21:51 ` Daniel Borkmann
2022-01-27 21:50 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 5+ messages in thread
From: Brendan Jackman @ 2022-01-27 10:48 UTC (permalink / raw)
To: Hou Tao
Cc: Alexei Starovoitov, John Fastabend, Martin KaFai Lau,
Yonghong Song, Daniel Borkmann, Andrii Nakryiko,
David S . Miller, Jakub Kicinski, netdev, bpf
Yep - BPF_SUB is also excluded in Documentation/networking/filter.rst,
plus the interpreter and verifier don't support it.
Thanks,
Acked-by: Brendan Jackman <jackmanb@google.com>
On Thu, 27 Jan 2022 at 09:17, Hou Tao <houtao1@huawei.com> wrote:
>
> According to the LLVM commit (https://reviews.llvm.org/D72184),
> sync_fetch_and_sub() is implemented as a negation followed by
> sync_fetch_and_add(), so there will be no BPF_SUB op and just
> remove it.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
> arch/x86/net/bpf_jit_comp.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index ce1f86f245c9..5d643ebb1e56 100644
> --- a/arch/x86/net/bpf_jit_comp.c
> +++ b/arch/x86/net/bpf_jit_comp.c
> @@ -787,7 +787,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
> /* emit opcode */
> switch (atomic_op) {
> case BPF_ADD:
> - case BPF_SUB:
> case BPF_AND:
> case BPF_OR:
> case BPF_XOR:
> --
> 2.29.2
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
2022-01-27 10:48 ` Brendan Jackman
@ 2022-01-27 21:51 ` Daniel Borkmann
2022-01-28 2:40 ` John Fastabend
0 siblings, 1 reply; 5+ messages in thread
From: Daniel Borkmann @ 2022-01-27 21:51 UTC (permalink / raw)
To: Brendan Jackman, Hou Tao
Cc: Alexei Starovoitov, John Fastabend, Martin KaFai Lau,
Yonghong Song, Andrii Nakryiko, David S . Miller, Jakub Kicinski,
netdev, bpf
On 1/27/22 11:48 AM, Brendan Jackman wrote:
> Yep - BPF_SUB is also excluded in Documentation/networking/filter.rst,
> plus the interpreter and verifier don't support it.
>
> Thanks,
>
> Acked-by: Brendan Jackman <jackmanb@google.com>
I was wondering about verifier specifically as well. Added a note to the
commit log that verifier rejects BPF_SUB while applying, thanks!
> On Thu, 27 Jan 2022 at 09:17, Hou Tao <houtao1@huawei.com> wrote:
>>
>> According to the LLVM commit (https://reviews.llvm.org/D72184),
>> sync_fetch_and_sub() is implemented as a negation followed by
>> sync_fetch_and_add(), so there will be no BPF_SUB op and just
>> remove it.
>>
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>> arch/x86/net/bpf_jit_comp.c | 1 -
>> 1 file changed, 1 deletion(-)
>>
>> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
>> index ce1f86f245c9..5d643ebb1e56 100644
>> --- a/arch/x86/net/bpf_jit_comp.c
>> +++ b/arch/x86/net/bpf_jit_comp.c
>> @@ -787,7 +787,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
>> /* emit opcode */
>> switch (atomic_op) {
>> case BPF_ADD:
>> - case BPF_SUB:
>> case BPF_AND:
>> case BPF_OR:
>> case BPF_XOR:
>> --
>> 2.29.2
>>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
2022-01-27 21:51 ` Daniel Borkmann
@ 2022-01-28 2:40 ` John Fastabend
0 siblings, 0 replies; 5+ messages in thread
From: John Fastabend @ 2022-01-28 2:40 UTC (permalink / raw)
To: Daniel Borkmann, Brendan Jackman, Hou Tao
Cc: Alexei Starovoitov, John Fastabend, Martin KaFai Lau,
Yonghong Song, Andrii Nakryiko, David S . Miller, Jakub Kicinski,
netdev, bpf
Daniel Borkmann wrote:
> On 1/27/22 11:48 AM, Brendan Jackman wrote:
> > Yep - BPF_SUB is also excluded in Documentation/networking/filter.rst,
> > plus the interpreter and verifier don't support it.
> >
> > Thanks,
> >
> > Acked-by: Brendan Jackman <jackmanb@google.com>
>
> I was wondering about verifier specifically as well. Added a note to the
> commit log that verifier rejects BPF_SUB while applying, thanks!
>
Thanks for the follow up Hou/Brendan LGTM as well. After its been
merged, but ACK from me as well.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
2022-01-27 8:32 [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op Hou Tao
2022-01-27 10:48 ` Brendan Jackman
@ 2022-01-27 21:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 5+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-01-27 21:50 UTC (permalink / raw)
To: Hou Tao
Cc: ast, john.fastabend, kafai, yhs, daniel, andrii, davem, kuba,
jackmanb, netdev, bpf
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:
On Thu, 27 Jan 2022 16:32:40 +0800 you wrote:
> According to the LLVM commit (https://reviews.llvm.org/D72184),
> sync_fetch_and_sub() is implemented as a negation followed by
> sync_fetch_and_add(), so there will be no BPF_SUB op and just
> remove it.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
>
> [...]
Here is the summary with links:
- [bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op
https://git.kernel.org/bpf/bpf-next/c/b6ec79518ef0
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-01-28 2:40 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2022-01-27 8:32 [PATCH bpf-next] bpf, x86: remove unnecessary handling of BPF_SUB atomic op Hou Tao
2022-01-27 10:48 ` Brendan Jackman
2022-01-27 21:51 ` Daniel Borkmann
2022-01-28 2:40 ` John Fastabend
2022-01-27 21:50 ` patchwork-bot+netdevbpf
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