Re: [PATCH v2 3/4] powerpc64/bpf: Add support for indirect jump

[Hari Bathini <hbathini@linux.ibm.com>]

On 27/02/26 7:13 am, adubey@linux.ibm.com wrote:
> From: Abhishek Dubey <adubey@linux.ibm.com>
> 
> Add support for a new instruction
> 
> 	BPF_JMP|BPF_X|BPF_JA, SRC=0, DST=Rx, off=0, imm=0
> 
> which does an indirect jump to a location stored in Rx. The
> register Rx should have type PTR_TO_INSN. This new type ensures
> that the Rx register contains a value (or a range of values)
> loaded from a correct jump table – map of type instruction array.
> 
> Support indirect jump to all registers in powerpc64 JIT using
> the ctr register. Move Rx content to ctr register, then invoke
> bctr instruction to branch to address stored in ctr register.
> Skip save and restore of TOC as the jump is always within the
> program context.
> 

Looks good to me.

Acked-by: Hari Bathini <hbathini@linux.ibm.com>

> Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
> ---
>   arch/powerpc/net/bpf_jit_comp64.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index c1d011046d8b..2cb550ca1dec 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -1627,6 +1627,14 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
>   			addrs[++i] = ctx->idx * 4;
>   			break;
>   
> +		/*
> +		 * JUMP reg
> +		 */
> +		case BPF_JMP | BPF_JA | BPF_X:
> +			EMIT(PPC_RAW_MTCTR(dst_reg));
> +			EMIT(PPC_RAW_BCTR());
> +			break;
> +
>   		/*
>   		 * Return/Exit
>   		 */