Re: [PATCH bpf] bpf, docs: Correct the example of BPF_XOR

From: David Vernet
Date: Tue Nov 29 2022 - 13:54:20 EST


On Tue, Nov 29, 2022 at 09:45:58PM +0800, Zheng Yejian wrote:
> Refer to description of BPF_XOR, dst_reg should be used but not src_reg
> in the examples.
>
> Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
> ---
> Documentation/bpf/instruction-set.rst | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
> index 5d798437dad4..e672d5ec6cc7 100644
> --- a/Documentation/bpf/instruction-set.rst
> +++ b/Documentation/bpf/instruction-set.rst
> @@ -122,11 +122,11 @@ BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below)
>
> ``BPF_XOR | BPF_K | BPF_ALU`` means::
>
> - src_reg = (u32) src_reg ^ (u32) imm32
> + dst_reg = (u32) dst_reg ^ (u32) imm32

Shouldn't this be

dst_reg = (u32) dst_reg ^ (u32) src_reg

Same idea below for 64 bit

>
> ``BPF_XOR | BPF_K | BPF_ALU64`` means::
>
> - src_reg = src_reg ^ imm32
> + dst_reg = dst_reg ^ imm32
>
>
> Byte swap instructions
> --
> 2.25.1
>