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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 75D41C4332B for ; Tue, 26 Jan 2021 20:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E62122A83 for ; Tue, 26 Jan 2021 20:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728207AbhAZFBr (ORCPT ); Tue, 26 Jan 2021 00:01:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:37502 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731158AbhAYSvj (ORCPT ); Mon, 25 Jan 2021 13:51:39 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8DF552083E; Mon, 25 Jan 2021 18:51:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611600675; bh=4xlM1I/vK0Zb5Neahpka7frgpb4IyD1ETQ1CY5n6wIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JLTMsNw/VvlnFb37JjiGsRdGrSKcZsoNnHq4T6TF1nDYAYzXnyLVjopKCnlrczdrs ow5stpSs/1ieuYZf3ace1U10eNTUeEEI7d6ScklWrTZOCIGl4BkeiRSFEe/57t30zR Uq1k2YSfj84vXLI132fDzGSiC9YVzn7/XkSdGZ6s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Will Deacon , James Morse , Catalin Marinas , Sasha Levin Subject: [PATCH 5.10 090/199] arm64: entry: remove redundant IRQ flag tracing Date: Mon, 25 Jan 2021 19:38:32 +0100 Message-Id: <20210125183220.070116605@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210125183216.245315437@linuxfoundation.org> References: <20210125183216.245315437@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mark Rutland [ Upstream commit df06824767cc9a32fbdb0e3d3b7e169292a5b5fe ] All EL0 returns go via ret_to_user(), which masks IRQs and notifies lockdep and tracing before calling into do_notify_resume(). Therefore, there's no need for do_notify_resume() to call trace_hardirqs_off(), and the comment is stale. The call is simply redundant. In ret_to_user() we call exit_to_user_mode(), which notifies lockdep and tracing the IRQs will be enabled in userspace, so there's no need for el0_svc_common() to call trace_hardirqs_on() before returning. Further, at the start of ret_to_user() we call trace_hardirqs_off(), so not only is this redundant, but it is immediately undone. In addition to being redundant, the trace_hardirqs_on() in el0_svc_common() leaves lockdep inconsistent with the hardware state, and is liable to cause issues for any C code or instrumentation between this and the call to trace_hardirqs_off() which undoes it in ret_to_user(). This patch removes the redundant tracing calls and associated stale comments. Fixes: 23529049c684 ("arm64: entry: fix non-NMI user<->kernel transitions") Signed-off-by: Mark Rutland Acked-by: Will Deacon Cc: James Morse Cc: Will Deacon Link: https://lore.kernel.org/r/20210107145310.44616-1-mark.rutland@arm.com Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- arch/arm64/kernel/signal.c | 7 ------- arch/arm64/kernel/syscall.c | 9 +-------- 2 files changed, 1 insertion(+), 15 deletions(-) diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index a8184cad88907..50852992752b0 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -914,13 +914,6 @@ static void do_signal(struct pt_regs *regs) asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) { - /* - * The assembly code enters us with IRQs off, but it hasn't - * informed the tracing code of that for efficiency reasons. - * Update the trace code with the current status. - */ - trace_hardirqs_off(); - do { /* Check valid user FS if needed */ addr_limit_user_check(); diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index f8f758e4a3064..6fa8cfb8232aa 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -165,15 +165,8 @@ 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; - if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) { - /* - * We're off to userspace, where interrupts are - * always enabled after we restore the flags from - * the SPSR. - */ - trace_hardirqs_on(); + if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) return; - } local_daif_restore(DAIF_PROCCTX); } -- 2.27.0