2023-09-07 18:22:52

by Russell King (Oracle)

Subject: Re: [PATCH bpf-next v2 6/8] arm32, bpf: add support for 64 bit division instruction

On Wed, Sep 06, 2023 at 06:33:18PM +0000, Puranjay Mohan wrote:
> + /* Recover {R3, R2} and {R1, R0} from stack if they are not Rd */
> + if (rd[1] != ARM_R0 && rd[1] != ARM_R2) {
> + emit(ARM_POP(BIT(ARM_R0) | BIT(ARM_R1)), ctx);
> + emit(ARM_POP(BIT(ARM_R2) | BIT(ARM_R3)), ctx);
> + } else if (rd[1] != ARM_R0) {
> + emit(ARM_POP(BIT(ARM_R0) | BIT(ARM_R1)), ctx);
> + emit(ARM_ADD_I(ARM_SP, ARM_SP, 8), ctx);
> + } else if (rd[1] != ARM_R2) {
> + emit(ARM_ADD_I(ARM_SP, ARM_SP, 8), ctx);
> + emit(ARM_POP(BIT(ARM_R2) | BIT(ARM_R3)), ctx);
> + } else {
> + emit(ARM_ADD_I(ARM_SP, ARM_SP, 16), ctx);
> + }

As mentioned in the continuing discussion of the previous patch series,
all these cases aren't reachable.

Thanks.

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