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

[Russell King (Oracle)]

On Wed, Sep 06, 2023 at 09:29:19AM +0000, Puranjay Mohan wrote:
> On Tue, Sep 05 2023, Russell King (Oracle) wrote:
> 
> > On Tue, Sep 05, 2023 at 09:06:19PM +0000, Puranjay Mohan wrote:
> Actually, there can also be a situation where rd[1] != ARM_R0 && rd[1] != ARM_R2,
> so should I do it like:
> 
>  	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);
>  	}

Are you sure all four states are possible?

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