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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D74E2CF8844 for ; Thu, 20 Nov 2025 12:04:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jv8wO1DtfkXsY/ae1Dg1/DwE8bP+V8jd6aqheqjiOgc=; b=TQs20KiW7ca27wyGR78O/8nb0z NScZlqAmhGPAsG+KGeoPY097tKsIOtrsxNKpSf9Fzd3iSOYjrN93WirrjOEzSSzhJELQE3NBfbPRB E4gViD2Rb1jW7Vk0Pgryuu8oX9d3eg8OBmm1JrzSgrsSV3lFkIvcxTVMuTeCflTPjYF6aYfxdG/B5 WVc7193w1NAX5MWRKBl7gtAVeg7tEx3hFZHnFGgO3gULaUr3NvlKRx8atxW04wkhDFFlgNxjuXSkb XRjkqMVtfd+ysG1EWWhbhxlAnS2rtgvgU8reT/5sFCSwAwGv0OmheLDhM+dsEOeuCZsWPT6RjvwR9 TTkJoung==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vM3OM-00000006dEh-2jAF; Thu, 20 Nov 2025 12:04:02 +0000 Received: from canpmsgout02.his.huawei.com ([113.46.200.217]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vM3OJ-00000006dDq-1PUI for linux-arm-kernel@lists.infradead.org; Thu, 20 Nov 2025 12:04:01 +0000 dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=jv8wO1DtfkXsY/ae1Dg1/DwE8bP+V8jd6aqheqjiOgc=; b=uMi81M090SzQpqt08FtTaGHZap8RoTOn41f2uoRuD3XvHjjAujVzUsQypK5sBntqbNvqK1JHf 3S0BpZTCKAMBQlch3lOYW/gAADx8wNxsQhQ6OZbTL+7vRqIC/KH6vveGLYgOOTqNPJl1EEax75O EsdG5hHKqxRUDUiGXbZUzh4= Received: from mail.maildlp.com (unknown [172.19.88.105]) by canpmsgout02.his.huawei.com (SkyGuard) with ESMTPS id 4dBxlv0v4LzcZxv; Thu, 20 Nov 2025 20:01:47 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id 688BE140159; Thu, 20 Nov 2025 20:03:51 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 20 Nov 2025 20:03:49 +0800 Message-ID: <7b317981-659c-fa02-d569-f832bfc09c9c@huawei.com> Date: Thu, 20 Nov 2025 20:03:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v7 03/11] arm64/ptrace: Refator el0_svc_common() Content-Language: en-US To: Kevin Brodsky , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20251117133048.53182-1-ruanjinjie@huawei.com> <20251117133048.53182-4-ruanjinjie@huawei.com> <57c2c83c-9eea-40e0-9f95-47f21b1c75be@arm.com> From: Jinjie Ruan In-Reply-To: <57c2c83c-9eea-40e0-9f95-47f21b1c75be@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf500011.china.huawei.com (7.185.36.131) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251120_040400_012169_32E5F2A0 X-CRM114-Status: GOOD ( 22.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2025/11/19 1:10, Kevin Brodsky wrote: > In subject: s/refator/refactor/ > > Also nit: this is less about ptrace than about syscall entry, so maybe > "arm64/syscall:"? > > On 17/11/2025 14:30, Jinjie Ruan wrote: >> Compared to the generic entry code, arm64 terminate the process > > s/terminate/terminates/ (similar observation for other commit messages) Will update it. > >> after report_syscall_exit() if the syscall is issued within >> a restartable sequence. > > Presumably this implies that forcing SIGSEGV before or after calling the > tracing handlers makes no difference, if so it should be clarified. It seems that it need a separate patch to clarify. > >> In preparation for moving arm64 over to the generic entry code, >> refactor el0_svc_common() as below: >> >> - Extract syscall_exit_to_user_mode_prepare() to replace the >> the combination of read_thread_flags() and syscall_trace_exit(), >> also move the syscall exit check logic into it. >> >> - Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is >> not needed. >> >> - Move has_syscall_work() helper into asm/syscall.h, which will be >> reused by ptrace.c. >> >> Signed-off-by: Jinjie Ruan >> --- >> arch/arm64/include/asm/syscall.h | 7 ++++++- >> arch/arm64/kernel/ptrace.c | 10 +++++++++- >> arch/arm64/kernel/syscall.c | 26 +++++--------------------- >> 3 files changed, 20 insertions(+), 23 deletions(-) >> >> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h >> index d69f590a989b..6225981fbbdb 100644 >> --- a/arch/arm64/include/asm/syscall.h >> +++ b/arch/arm64/include/asm/syscall.h >> @@ -114,7 +114,12 @@ static inline int syscall_get_arch(struct task_struct *task) >> return AUDIT_ARCH_AARCH64; >> } >> >> +static inline bool has_syscall_work(unsigned long flags) >> +{ >> + return unlikely(flags & _TIF_SYSCALL_WORK); >> +} >> + >> int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags); >> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); >> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs); >> >> #endif /* __ASM_SYSCALL_H */ >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c >> index bbb868f6b292..95984bbf53db 100644 >> --- a/arch/arm64/kernel/ptrace.c >> +++ b/arch/arm64/kernel/ptrace.c >> @@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) >> return regs->syscallno; >> } >> >> -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) >> +static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) >> { >> audit_syscall_exit(regs); >> >> @@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) >> >> if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)) >> report_syscall_exit(regs); >> +} >> + >> +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) >> +{ >> + unsigned long flags = read_thread_flags(); >> >> rseq_syscall(regs); >> + >> + if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) >> + syscall_trace_exit(regs, flags); > > Since we're trying to align as much with the generic code as possible, > we might as well rename this function to syscall_exit_work() as well. Yes, syscall_trace_exit() is very similar to syscall_exit_work(). > >> } >> >> /* >> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c >> index 6e3fe760e0bb..9713b038d750 100644 >> --- a/arch/arm64/kernel/syscall.c >> +++ b/arch/arm64/kernel/syscall.c >> @@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, >> choose_random_kstack_offset(get_random_u16()); >> } >> >> -static inline bool has_syscall_work(unsigned long flags) >> -{ >> - return unlikely(flags & _TIF_SYSCALL_WORK); >> -} >> - >> static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, >> const syscall_fn_t syscall_table[]) >> { >> @@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, >> if (scno == NO_SYSCALL) >> syscall_set_return_value(current, regs, -ENOSYS, 0); >> scno = syscall_trace_enter(regs, regs->syscallno, flags); >> - if (scno == NO_SYSCALL) >> - goto trace_exit; > > Why not keep the goto instead of duplicating the call? It could be > renamed if necessary. That is good. > > - Kevin > >> + if (scno == NO_SYSCALL) { >> + syscall_exit_to_user_mode_prepare(regs); >> + return; >> + } >> } >> >> invoke_syscall(regs, scno, sc_nr, syscall_table); >> >> - /* >> - * The tracing status may have changed under our feet, so we have to >> - * check again. However, if we were tracing entry, then we always trace >> - * exit regardless, as the old entry assembly did. >> - */ >> - if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) { >> - flags = read_thread_flags(); >> - if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) >> - return; >> - } >> - >> -trace_exit: >> - flags = read_thread_flags(); >> - syscall_trace_exit(regs, flags); >> + syscall_exit_to_user_mode_prepare(regs); >> } >> >> void do_el0_svc(struct pt_regs *regs) >