From nobody Thu Apr 2 19:51:32 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DECFDECAAD8 for ; Wed, 21 Sep 2022 07:41:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229987AbiIUHlr (ORCPT ); Wed, 21 Sep 2022 03:41:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230317AbiIUHl1 (ORCPT ); Wed, 21 Sep 2022 03:41:27 -0400 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6A7BF303C3 for ; Wed, 21 Sep 2022 00:41:25 -0700 (PDT) Received: from localhost.localdomain.localdomain (unknown [111.9.175.10]) by localhost.localdomain (Coremail) with SMTP id AQAAf8CxT+AZwCpjyE0fAA--.52706S2; Wed, 21 Sep 2022 15:41:15 +0800 (CST) From: Jinyang He To: Huacai Chen , WANG Xuerui , Oleg Nesterov Cc: Jinyang He , loongarch@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v2] LoongArch: Remove unused kernel stack padding Date: Wed, 21 Sep 2022 15:41:13 +0800 Message-Id: <1663746073-12584-1-git-send-email-hejinyang@loongson.cn> X-Mailer: git-send-email 2.1.0 X-CM-TRANSID: AQAAf8CxT+AZwCpjyE0fAA--.52706S2 X-Coremail-Antispam: 1UD129KBjvJXoWxZF4DKw4DuF4Uur4UKF4UArb_yoWrXry7pF 9rAw1DGr4jkFnYyryDtrs8ZryDJwn7Kw1aga17ta4rArnFqF1rZryxAryDXFyYqa95Kay0 gFy3Kwsxta15X3JanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUym14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij64vI r41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8Gjc xK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0 cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8V AvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E 14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUywZ7UUUUU= X-CM-SenderInfo: pkhmx0p1dqwqxorr0wxvrqhubq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Kernel stack padding looks like obey MIPS o32 Calling Convention, as LoongArch is inspired by MIPS and keep it. Remove it avoid not clear code. Link: https://lore.kernel.org/loongarch/1662130897-13156-1-git-send-email-h= ejinyang@loongson.cn/ Signed-off-by: Jinyang He --- v2: Remove TOP_OF_KERNEL_STACK_PADDING Remove 'init stack pointer' in head.S arch/loongarch/include/asm/processor.h | 2 +- arch/loongarch/include/asm/ptrace.h | 2 +- arch/loongarch/kernel/head.S | 3 +-- arch/loongarch/kernel/process.c | 4 ++-- arch/loongarch/kernel/switch.S | 2 +- 5 files changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/includ= e/asm/processor.h index 1c4b4308378d..780e0d39f638 100644 --- a/arch/loongarch/include/asm/processor.h +++ b/arch/loongarch/include/asm/processor.h @@ -194,7 +194,7 @@ static inline void flush_thread(void) unsigned long __get_wchan(struct task_struct *p); =20 #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \ - THREAD_SIZE - 32 - sizeof(struct pt_regs)) + THREAD_SIZE - sizeof(struct pt_regs)) #define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk)) #define KSTK_EIP(tsk) (task_pt_regs(tsk)->csr_era) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[3]) diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/a= sm/ptrace.h index 17838c6b7ccd..82649a78fec1 100644 --- a/arch/loongarch/include/asm/ptrace.h +++ b/arch/loongarch/include/asm/ptrace.h @@ -133,7 +133,7 @@ static inline void die_if_kernel(const char *str, struc= t pt_regs *regs) #define current_pt_regs() \ ({ \ unsigned long sp =3D (unsigned long)__builtin_frame_address(0); \ - (struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1 - 32) - 1; \ + (struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1) - 1; \ }) =20 /* Helpers for working with the user stack pointer */ diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S index 4d352230fbc3..0e1752fbc857 100644 --- a/arch/loongarch/kernel/head.S +++ b/arch/loongarch/kernel/head.S @@ -81,10 +81,9 @@ SYM_CODE_START(kernel_entry) # kernel entry point =20 la.pcrel tp, init_thread_union /* Set the SP after an empty pt_regs. */ - PTR_LI sp, (_THREAD_SIZE - 32 - PT_SIZE) + PTR_LI sp, (_THREAD_SIZE - PT_SIZE) PTR_ADD sp, sp, tp set_saved_sp sp, t0, t1 - PTR_ADDI sp, sp, -4 * SZREG # init stack pointer =20 bl start_kernel =20 diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/proces= s.c index 660492f064e7..dae087d6c458 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -129,7 +129,7 @@ int copy_thread(struct task_struct *p, const struct ker= nel_clone_args *args) unsigned long clone_flags =3D args->flags; struct pt_regs *childregs, *regs =3D current_pt_regs(); =20 - childksp =3D (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; + childksp =3D (unsigned long)task_stack_page(p) + THREAD_SIZE; =20 /* set up new TSS. */ childregs =3D (struct pt_regs *) childksp - 1; @@ -236,7 +236,7 @@ bool in_task_stack(unsigned long stack, struct task_str= uct *task, struct stack_info *info) { unsigned long begin =3D (unsigned long)task_stack_page(task); - unsigned long end =3D begin + THREAD_SIZE - 32; + unsigned long end =3D begin + THREAD_SIZE; =20 if (stack < begin || stack >=3D end) return false; diff --git a/arch/loongarch/kernel/switch.S b/arch/loongarch/kernel/switch.S index 43ebbc3990f7..202a163cb32f 100644 --- a/arch/loongarch/kernel/switch.S +++ b/arch/loongarch/kernel/switch.S @@ -26,7 +26,7 @@ SYM_FUNC_START(__switch_to) move tp, a2 cpu_restore_nonscratch a1 =20 - li.w t0, _THREAD_SIZE - 32 + li.w t0, _THREAD_SIZE PTR_ADD t0, t0, tp set_saved_sp t0, t1, t2 =20 --=20 2.31.1