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

[Russell King (Oracle)]

On Tue, Sep 05, 2023 at 09:06:19PM +0000, Puranjay Mohan wrote:
> +cont:
> +
> +	/* Call appropriate function */
> +	if (sign)
> +		emit_mov_i(ARM_IP, op == BPF_DIV ? (u32)jit_sdiv64 : (u32)jit_smod64, ctx);
> +	else
> +		emit_mov_i(ARM_IP, op == BPF_DIV ? (u32)jit_udiv64 : (u32)jit_mod64, ctx);

Same comment as the previous patch here.

> +
> +	emit_blx_r(ARM_IP, ctx);
> +
> +	/* Save return value */
> +	if (rd[1] != ARM_R0) {
> +		emit(ARM_MOV_R(rd[0], ARM_R1), ctx);
> +		emit(ARM_MOV_R(rd[1], ARM_R0), ctx);
> +	}
> +
> +	/* Recover {R1, R0} from stack if it is not Rd */
> +	if (rd[1] != ARM_R0)
> +		emit(ARM_POP(BIT(ARM_R0) | BIT(ARM_R1)), ctx);
> +	else
> +		emit(ARM_ADD_I(ARM_SP, ARM_SP, 8), ctx);
> +
> +	/* Recover {R3, R2} from stack if it is not Rd */
> +	if (rd[1] != ARM_R2)
> +		emit(ARM_POP(BIT(ARM_R2) | BIT(ARM_R3)), ctx);
> +	else
> +		emit(ARM_ADD_I(ARM_SP, ARM_SP, 8), ctx);

	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);
	}

Hmm?

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