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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 715D6C48BD1 for ; Wed, 9 Jun 2021 12:20:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52D6860E0C for ; Wed, 9 Jun 2021 12:20:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239768AbhFIMWd (ORCPT ); Wed, 9 Jun 2021 08:22:33 -0400 Received: from foss.arm.com ([217.140.110.172]:58628 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235842AbhFIMWZ (ORCPT ); Wed, 9 Jun 2021 08:22:25 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 95DB21480; Wed, 9 Jun 2021 05:20:30 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 791353F73D; Wed, 9 Jun 2021 05:20:27 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: benh@kernel.crashing.org, boqun.feng@gmail.com, bp@alien8.de, catalin.marinas@arm.com, dvyukov@google.com, elver@google.com, ink@jurassic.park.msu.ru, jonas@southpole.se, juri.lelli@redhat.com, linux@armlinux.org.uk, luto@kernel.org, mark.rutland@arm.com, mattst88@gmail.com, mingo@redhat.com, monstr@monstr.eu, mpe@ellerman.id.au, paulmck@kernel.org, paulus@samba.org, peterz@infradead.org, rth@twiddle.net, shorne@gmail.com, stefan.kristiansson@saunalahti.fi, tglx@linutronix.de, vincent.guittot@linaro.org, will@kernel.org Subject: [RFC PATCH 06/10] arm64: read thread flags Date: Wed, 9 Jun 2021 13:19:57 +0100 Message-Id: <20210609122001.18277-7-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210609122001.18277-1-mark.rutland@arm.com> References: <20210609122001.18277-1-mark.rutland@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, we should snapshot the flags prior to using them. Let's use the new helpers to do so on arm64. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon --- arch/arm64/kernel/ptrace.c | 4 ++-- arch/arm64/kernel/signal.c | 2 +- arch/arm64/kernel/syscall.c | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index eb2f73939b7b..a6103b997664 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1834,7 +1834,7 @@ static void tracehook_report_syscall(struct pt_regs *regs, int syscall_trace_enter(struct pt_regs *regs) { - unsigned long flags = READ_ONCE(current_thread_info()->flags); + unsigned long flags = read_thread_flags(); if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); @@ -1857,7 +1857,7 @@ int syscall_trace_enter(struct pt_regs *regs) void syscall_trace_exit(struct pt_regs *regs) { - unsigned long flags = READ_ONCE(current_thread_info()->flags); + unsigned long flags = read_thread_flags(); audit_syscall_exit(regs); diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 6237486ff6bb..ed113659425d 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -945,7 +945,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, } local_daif_mask(); - thread_flags = READ_ONCE(current_thread_info()->flags); + thread_flags = read_thead_flags(); } while (thread_flags & _TIF_WORK_MASK); } diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index 263d6c1a525f..badf1789dc3d 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -84,7 +84,7 @@ void syscall_trace_exit(struct pt_regs *regs); static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, const syscall_fn_t syscall_table[]) { - unsigned long flags = current_thread_info()->flags; + unsigned long flags = read_thread_flags(); regs->orig_x0 = regs->regs[0]; regs->syscallno = scno; @@ -151,7 +151,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, */ if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) { local_daif_mask(); - flags = current_thread_info()->flags; + flags = read_thread_flags(); if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) return; local_daif_restore(DAIF_PROCCTX); -- 2.11.0