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

[Puranjay Mohan]

On Wed, Sep 06 2023, Russell King (Oracle) wrote:

> 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?

ohh!

I just realized that the last else will never run.
rd[1] can never be equal to both ARM_R0 and ARM_R2.
Will fix it in V3 as I already sent out the V2.

I need to learn to leave patches on the list for few days before re-spinning.

Thanks,
Puranjay