From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E981FC433EF for ; Mon, 25 Oct 2021 02:11:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3E0161002 for ; Mon, 25 Oct 2021 02:11:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231912AbhJYCOI (ORCPT ); Sun, 24 Oct 2021 22:14:08 -0400 Received: from mail.loongson.cn ([114.242.206.163]:34686 "EHLO loongson.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231516AbhJYCOG (ORCPT ); Sun, 24 Oct 2021 22:14:06 -0400 Received: from localhost.localdomain (unknown [111.9.175.10]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9Cx9OVXEnZhn5IfAA--.56913S3; Mon, 25 Oct 2021 10:11:37 +0800 (CST) Subject: Re: [PATCH 4/4] MIPS: Add is_jr_ra_ins() to end the loop early To: "Maciej W. Rozycki" References: <1610454557-25867-1-git-send-email-hejinyang@loongson.cn> <1610454557-25867-5-git-send-email-hejinyang@loongson.cn> Cc: Thomas Bogendoerfer , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Burton , Jun-Ru Chang From: Jinyang He Message-ID: <228e5765-6fe6-9cdc-4d37-2a0e4406ee8e@loongson.cn> Date: Mon, 25 Oct 2021 10:11:35 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf9Cx9OVXEnZhn5IfAA--.56913S3 X-Coremail-Antispam: 1UD129KBjvJXoW7AF1kuryDKw1kKw1fWr4xXrb_yoW8uF4UpF 45A3Z8KrW8X34fK3sxtrWrXryYqrs5KwsxKFWxtrW0v3Z8Wr1xZrySyrs0k3y8Ar1Fk3W0 vF90vr1jkw1qv3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUklb7Iv0xC_Kw4lb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjc xK6I8E87Iv6xkF7I0E14v26F4UJVW0owAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40E FcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr 0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxk0xIA0c2IEe2xFo4CEbIxv r21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxV WUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI 7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r 1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4U MIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7IU56c_DUUUU U== X-CM-SenderInfo: pkhmx0p1dqwqxorr0wxvrqhubq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/24/2021 02:32 AM, Maciej W. Rozycki wrote: > On Tue, 12 Jan 2021, Jinyang He wrote: > >> For those leaf functions, they are likely to have no stack operations. >> Add is_jr_ra_ins() to determine whether jr ra has been touched before >> the frame_size is found. Without this patch, the get frame_size operation >> may be out of range and get the frame_size from the next nested function. >> >> Signed-off-by: Jinyang He >> --- >> arch/mips/kernel/process.c | 34 +++++++++++++++++++++++++++++++++- >> 1 file changed, 33 insertions(+), 1 deletion(-) >> >> diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c >> index bef8f8d..9e6f194 100644 >> --- a/arch/mips/kernel/process.c >> +++ b/arch/mips/kernel/process.c >> @@ -205,6 +205,36 @@ struct mips_frame_info { >> #define J_TARGET(pc,target) \ >> (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) >> >> +static inline int is_jr_ra_ins(union mips_instruction *ip) >> +{ >> +#ifdef CONFIG_CPU_MICROMIPS >> + /* >> + * jr16 ra >> + * jr ra >> + */ >> + if (mm_insn_16bit(ip->word >> 16)) { >> + if (ip->mm16_r5_format.opcode == mm_pool16c_op && >> + ip->mm16_r5_format.rt == mm_jr16_op && >> + ip->mm16_r5_format.imm == 31) >> + return 1; >> + return 0; >> + } >> + >> + if (ip->r_format.opcode == mm_pool32a_op && >> + ip->r_format.func == mm_pool32axf_op && >> + ((ip->u_format.uimmediate >> 6) & GENMASK(9,0)) == mm_jalr_op && >> + ip->r_format.rs == 31) >> + return 1; >> + return 0; >> +#else > Without looking into it much, this is likely missing the point, because > while technically inteed JR and JR16 can be used with $ra in microMIPS > machine code (there's JRS too), in reality either JRC or JRADDIUSP will. > > [Wading through e-mail recovered from mid-Jan linux-mips.org crash.] > > Maciej You are right, I missed the point. I have refered to microMIPS64 Instruction Set. JRC and JRADDIUSP also can be used with $ra in microMIPS. I am not sure what compiler do at epilogue. But when we call $ra without saving $ra, it means return, I think. I will fix it later. Thanks, Jinyang.