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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 EB29EC47083 for ; Wed, 2 Jun 2021 16:48:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D774A610A1 for ; Wed, 2 Jun 2021 16:48:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230412AbhFBQuf (ORCPT ); Wed, 2 Jun 2021 12:50:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:33758 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231419AbhFBQuZ (ORCPT ); Wed, 2 Jun 2021 12:50:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5EDB361C36; Wed, 2 Jun 2021 16:48:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622652521; bh=JTF5Ih+wHsSwNkOV9+aFa0YhP8VlA+J9HSmVI6cfyrc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d0MsGlrtYz97dhtHYFoqXe73OcbHD1F9P3uHPb6fqi6zpINGnEEV/SbAxDe/+MqfO ywHUj/bbt75wx8bYB2RAxQTHaaTyBY/dFL3BGe9AAFToaKvbrhiR9PrkUCz8ZYjtBP EBp3Qzm4wD3BxZSw3/KWXbDhoBC73/VbeL5DtZ8I0KQypJ8lpx7c1Zgbd2dVR7Dt79 v9EVXMW2g0zgHozZ4qgu4dXkJZ/vYGujKAb/qL3RM/DJpUX0P84q7Hj1xp2ia+7R92 zyBkb9FZkbkMSid0vSD/i1m1wgdSQuObtiXh3R1NwV2uBWZ5EHzUCx+1vVJpJ62zai byUIJ9sttE7Pw== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , Valentin Schneider , kernel-team@android.com Subject: [PATCH v8 18/19] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Date: Wed, 2 Jun 2021 17:47:18 +0100 Message-Id: <20210602164719.31777-19-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210602164719.31777-1-will@kernel.org> References: <20210602164719.31777-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The scheduler now knows enough about these braindead systems to place 32-bit tasks accordingly, so throw out the safety checks and allow the ret-to-user path to avoid do_notify_resume() if there is nothing to do. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/kernel/process.c | 14 +------------- arch/arm64/kernel/signal.c | 26 -------------------------- 2 files changed, 1 insertion(+), 39 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 3aea06fdd1f9..5581c376644e 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -528,15 +528,6 @@ static void erratum_1418040_thread_switch(struct task_struct *prev, write_sysreg(val, cntkctl_el1); } -static void compat_thread_switch(struct task_struct *next) -{ - if (!is_compat_thread(task_thread_info(next))) - return; - - if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) - set_tsk_thread_flag(next, TIF_NOTIFY_RESUME); -} - static void update_sctlr_el1(u64 sctlr) { /* @@ -578,7 +569,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, ssbs_thread_switch(next); erratum_1418040_thread_switch(prev, next); ptrauth_thread_switch_user(next); - compat_thread_switch(next); /* * Complete any pending TLB or cache maintenance on this CPU in case @@ -680,10 +670,8 @@ void arch_setup_new_exec(void) * at the point of execve(), although we try a bit harder to * honour the cpuset hierarchy. */ - if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) { + if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) force_compatible_cpus_allowed_ptr(current); - set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); - } } else if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) { relax_compatible_cpus_allowed_ptr(current); } diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index f8192f4ae0b8..6237486ff6bb 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -911,19 +911,6 @@ static void do_signal(struct pt_regs *regs) restore_saved_sigmask(); } -static bool cpu_affinity_invalid(struct pt_regs *regs) -{ - if (!compat_user_mode(regs)) - return false; - - /* - * We're preemptible, but a reschedule will cause us to check the - * affinity again. - */ - return !cpumask_test_cpu(raw_smp_processor_id(), - system_32bit_el0_cpumask()); -} - asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) { @@ -951,19 +938,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, if (thread_flags & _TIF_NOTIFY_RESUME) { tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); - - /* - * If we reschedule after checking the affinity - * then we must ensure that TIF_NOTIFY_RESUME - * is set so that we check the affinity again. - * Since tracehook_notify_resume() clears the - * flag, ensure that the compiler doesn't move - * it after the affinity check. - */ - barrier(); - - if (cpu_affinity_invalid(regs)) - force_sig(SIGKILL); } if (thread_flags & _TIF_FOREIGN_FPSTATE) -- 2.32.0.rc0.204.g9fa02ecfa5-goog