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Date:   Tue, 5 Sep 2023 22:50:23 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Puranjay Mohan <puranjay12@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>,
        Yonghong Song <yonghong.song@linux.dev>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Shubham Bansal <illusionist.neo@gmail.com>,
        Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
        bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next 6/8] arm32, bpf: add support for 64 bit division
 instruction
Message-ID: <ZPein8oS5egqGwzp@shell.armlinux.org.uk>
References: <20230905210621.1711859-1-puranjay12@gmail.com>
 <20230905210621.1711859-7-puranjay12@gmail.com>
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>
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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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