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 D1F39CD37B9 for ; Mon, 11 May 2026 09:22:31 +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-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:To:From:Reply-To:Cc:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=H41jepRbzKsmWnrdzhr6aJyxunmF1jWnbMyJErzNgrQ=; b=OXDNS+FvVFDhvIr5sJsufBRzpM zj0wsSR3t8g3D1vqZizdQWPgYWZbAGaUPZnwi8XmPwi103lMpWW3jXjFyD1f8wjPbShRXF1vqBUqV pAWPSGYcUaz/oDGYhvh1UjOi7krHpZbyx2d79ThRH/sQUT5DpH4UhMcBOWiKxy4amWzY+bVo+PULD wJMypwWwDyWzfF9nyLGvz381503XHJwgUEWkPFvonP7snMdCLFsMRpEk65dz+G3mmL9J+eK0GDjBy JuLZ1VM4UOmzhsbz07ONj/6Z1elJQ8l5YCqzAqUDOzU1jE0QgBcR6AKTRMV6BF3OhVAPv5zEHtrAA BaIBVA9w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMMqE-0000000CtCk-1yKq; Mon, 11 May 2026 09:22:22 +0000 Received: from canpmsgout10.his.huawei.com ([113.46.200.225]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMMq0-0000000CswX-2cRG for linux-arm-kernel@lists.infradead.org; Mon, 11 May 2026 09:22:14 +0000 dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=H41jepRbzKsmWnrdzhr6aJyxunmF1jWnbMyJErzNgrQ=; b=efqEWLdnU/91H/vAw2v4t5dsy47yDyd+SyPfD6F22lXtHYHWXsyVWt/GXLJ6poUmGo9fSna9v BU8yd49n8l4qnQCXBIU5UDcbLGqHgb13UJX8UGW+xGWGebyVJ/JlYk8L8halWW9P+arywlzJ5ny Fqn8ufDm4CkYtawriZz/E+o= Received: from mail.maildlp.com (unknown [172.19.163.15]) by canpmsgout10.his.huawei.com (SkyGuard) with ESMTPS id 4gDYvQ5wZ8z1K96p; Mon, 11 May 2026 17:14:26 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id 5371740573; Mon, 11 May 2026 17:22:01 +0800 (CST) Received: from huawei.com (10.90.53.73) 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; Mon, 11 May 2026 17:21:59 +0800 From: Jinjie Ruan To: , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v15 07/11] arm64: syscall: Introduce syscall_exit_to_user_mode_work() Date: Mon, 11 May 2026 17:20:59 +0800 Message-ID: <20260511092103.1974980-8-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260511092103.1974980-1-ruanjinjie@huawei.com> References: <20260511092103.1974980-1-ruanjinjie@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.90.53.73] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To dggpemf500011.china.huawei.com (7.185.36.131) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260511_022209_155466_8B13779C X-CRM114-Status: GOOD ( 17.00 ) 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 Refactor the system call exit path to align with the generic entry framework. This consolidates thread flag checking, rseq handling, and syscall tracing into a structure that mirrors the generic syscall_exit_to_user_mode_work() implementation. [Rationale] The generic entry code employs a hierarchical approach for syscall exit work: 1. syscall_exit_to_user_mode_work(): The entry point that handles rseq and checks if further exit work (tracing/audit) is required. 2. syscall_exit_work(): Performs the actual tracing, auditing, and ptrace reporting. [Changes] - Rename and Encapsulate: Rename syscall_trace_exit() to syscall_exit_work() and make it static, as it is now an internal helper for the exit path. - New Entry Point: Implement syscall_exit_to_user_mode_work() to replace the manual flag-reading logic in el0_svc_common(). This function now encapsulates the rseq_syscall() call and the conditional execution of syscall_exit_work(). - Simplify el0_svc_common(): Remove the complex conditional checks for tracing and CONFIG_DEBUG_RSEQ at the end of the syscall path, delegating this responsibility to the new helper. - Helper Migration: Move has_syscall_work() to asm/syscall.h to allow its reuse across ptrace.c and syscall.c. - Clean up RSEQ: Remove the explicit IS_ENABLED(CONFIG_DEBUG_RSEQ) check in the caller, as rseq_syscall() is already a no-op when the config is disabled. Cc: Mark Rutland Cc: Will Deacon Cc: Catalin Marinas Reviewed-by: Linus Walleij Reviewed-by: Yeoreum Yun Reviewed-by: Kevin Brodsky Signed-off-by: Jinjie Ruan --- v15 - Make syscall_exit_to_user_mode_work() __always_inline to keep the fast-path performance as Sashiko pointed out. --- arch/arm64/include/asm/syscall.h | 18 +++++++++++++++++- arch/arm64/kernel/ptrace.c | 5 +---- arch/arm64/kernel/syscall.c | 20 +------------------- 3 files changed, 19 insertions(+), 24 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 30b203ef156b..b331e09b937f 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -8,6 +8,7 @@ #include #include #include +#include typedef long (*syscall_fn_t)(const struct pt_regs *regs); @@ -121,6 +122,21 @@ static inline int syscall_get_arch(struct task_struct *task) } int syscall_trace_enter(struct pt_regs *regs, unsigned long flags); -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); +void syscall_exit_work(struct pt_regs *regs, unsigned long flags); + +static inline bool has_syscall_work(unsigned long flags) +{ + return unlikely(flags & _TIF_SYSCALL_WORK); +} + +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +{ + unsigned long flags = read_thread_flags(); + + rseq_syscall(regs); + + if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) + syscall_exit_work(regs, flags); +} #endif /* __ASM_SYSCALL_H */ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 15a45eeb56da..256aa20377e1 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -28,7 +28,6 @@ #include #include #include -#include #include #include @@ -2454,10 +2453,8 @@ int syscall_trace_enter(struct pt_regs *regs, unsigned long flags) return syscall; } -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) +void syscall_exit_work(struct pt_regs *regs, unsigned long flags) { - rseq_syscall(regs); - audit_syscall_exit(regs); if (flags & _TIF_SYSCALL_TRACEPOINT) diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index f6f87b042995..dac7bcc4bbdf 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -54,11 +54,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, syscall_set_return_value(current, regs, 0, ret); } -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[]) { @@ -120,21 +115,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, } 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_work(regs); } void do_el0_svc(struct pt_regs *regs) -- 2.34.1