From patchwork Thu Apr 10 14:21:39 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 14046592 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 1101FC3601E for ; Thu, 10 Apr 2025 14:24:21 +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:MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=qgGOsLRSny5mKTi2HoGDW1pf/YDOLuQ0yEc3IdQg7SM=; b=Hkb277atuqms8dxYhcQn9GY+IM 26r/gaSv6ei29rBy2WzyoD7vkDpVq/BZaEz7gHBEc/IHIY6H6T30Ycx+PsVw9N9luYMtqriFh10Qw eJL0ZKbxgiTfH3PNs39KicNsisiE1y6rlDh9XS36BtwQ27M1L7wkUFjj0yJGATce/7XB3tUnnf6XO xKIGxcGlGbx3++RdqvY2bbcTYVZUU8mDhwEHpimBcG9HumbVneHepB02fQzxc/+9hy8KFRdyStuXz K14+bAGRSKNZmneZx5tjgYfJK+njgn9NW3t8WmCDEBTnnVaPOBaB4AEGc5Em0yNpgwI/WCZ8+tv9p hbIknQGg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2sp5-0000000Apu1-051V; Thu, 10 Apr 2025 14:24:07 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2smm-0000000ApPv-2Sin for linux-arm-kernel@lists.infradead.org; Thu, 10 Apr 2025 14:21:46 +0000 Date: Thu, 10 Apr 2025 16:21:39 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1744294901; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=qgGOsLRSny5mKTi2HoGDW1pf/YDOLuQ0yEc3IdQg7SM=; b=K5bRj0DI46s7Hj9YciNz7p79NgRoiK+VKZfyrYmgeNkkYjW9p03DbT0+vYM6xhBRt+WsgY JDapZJ3+wGjR6I/2IPYMW5jAdOWCgbFkI7oG07evYmXdhBYd4/+HBg8NeCJ6Bj/5+d0Gsv +/XJVhZ836sw88bEFz3LnSJjepQN2n7eMfLPF4dK5nk2KPaGmeA4h1+rJEfsWYISbU+nBz JW2LaqFJOTF2vUVYubwYrkPN0twoJFU4lgESqxtbxYMrrgXYpit4sYqOkjsWfLdjUc3ZPO M00YpYdkJZo0FfuJXgMdfdM25pWBg1SjCwshk1YW0/9AMBqRir/cdzPy8N+kzQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1744294901; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=qgGOsLRSny5mKTi2HoGDW1pf/YDOLuQ0yEc3IdQg7SM=; b=eUIZDpyaNmHI7BKC7kTfcAqjOuqXbl3qk39GrtfBWrDlTihMu/RDdo6A46ss6oLV+VVDg5 +XlOZWNwKcE3zICQ== From: Sebastian Andrzej Siewior To: linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Jinjie Ruan , Juri Lelli , Kristina Martsenko , Mark Brown , Mark Rutland , Mike Galbraith , Neeraj Upadhyay , Peter Collingbourne , Petr Tesarik , Phil Auld , Thiago Jung Bauermann , Thomas Gleixner , Valentin Schneider , Will Deacon Subject: [PATCH v2] arm64: enable PREEMPT_LAZY Message-ID: <20250410142139.h5iV134E@linutronix.de> MIME-Version: 1.0 Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250410_072144_911781_C561EF2E X-CRM114-Status: GOOD ( 11.59 ) 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 From: Mark Rutland For an architecture to enable CONFIG_ARCH_HAS_RESCHED_LAZY, two things are required: 1) Adding a TIF_NEED_RESCHED_LAZY flag definition 2) Checking for TIF_NEED_RESCHED_LAZY in the appropriate locations 2) is handled in a generic manner by CONFIG_GENERIC_ENTRY, which isn't (yet) implemented for arm64. However, outside of core scheduler code, TIF_NEED_RESCHED_LAZY only needs to be checked on a kernel exit, meaning: o return/entry to userspace. o return/entry to guest. The return/entry to a guest is all handled by xfer_to_guest_mode_handle_work() which already does the right thing, so it can be left as-is. arm64 doesn't use common entry's exit_to_user_mode_prepare(), so update its return to user path to check for TIF_NEED_RESCHED_LAZY and call into schedule() accordingly. Link: https://lore.kernel.org/linux-rt-users/20241216190451.1c61977c@mordecai.tesarici.cz/ Link: https://lore.kernel.org/all/xhsmh4j0fl0p3.mognet@vschneid-thinkpadt14sgen2i.remote.csb/ Signed-off-by: Mark Rutland [testdrive, _TIF_WORK_MASK fixlet and changelog.] Signed-off-by: Mike Galbraith [Another round of testing; changelog faff] Signed-off-by: Valentin Schneider Reviewed-by: Sebastian Andrzej Siewior Acked-by: Mark Rutland Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20250305104925.189198-2-vschneid@redhat.com Signed-off-by: Sebastian Andrzej Siewior --- v1…v2: Repost of https://lore.kernel.org/all/20250305104925.189198-1-vschneid@redhat.com arch/arm64/Kconfig | 1 + arch/arm64/include/asm/thread_info.h | 16 +++++++++------- arch/arm64/kernel/entry-common.c | 2 +- 3 files changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index a182295e6f08b..84e3094b00ef2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -42,6 +42,7 @@ config ARM64 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE select ARCH_HAS_NONLEAF_PMD_YOUNG if ARM64_HAFT + select ARCH_HAS_PREEMPT_LAZY select ARCH_HAS_PTDUMP select ARCH_HAS_PTE_DEVMAP select ARCH_HAS_PTE_SPECIAL diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 1114c1c3300a1..4443ef2789758 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -59,11 +59,12 @@ void arch_setup_new_exec(void); #define TIF_SIGPENDING 0 /* signal pending */ #define TIF_NEED_RESCHED 1 /* rescheduling necessary */ -#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */ -#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */ -#define TIF_UPROBE 4 /* uprobe breakpoint or singlestep */ -#define TIF_MTE_ASYNC_FAULT 5 /* MTE Asynchronous Tag Check Fault */ -#define TIF_NOTIFY_SIGNAL 6 /* signal notifications exist */ +#define TIF_NEED_RESCHED_LAZY 2 /* Lazy rescheduling needed */ +#define TIF_NOTIFY_RESUME 3 /* callback before returning to user */ +#define TIF_FOREIGN_FPSTATE 4 /* CPU's FP state is not current's */ +#define TIF_UPROBE 5 /* uprobe breakpoint or singlestep */ +#define TIF_MTE_ASYNC_FAULT 6 /* MTE Asynchronous Tag Check Fault */ +#define TIF_NOTIFY_SIGNAL 7 /* signal notifications exist */ #define TIF_SYSCALL_TRACE 8 /* syscall trace active */ #define TIF_SYSCALL_AUDIT 9 /* syscall auditing */ #define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ @@ -85,6 +86,7 @@ void arch_setup_new_exec(void); #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) +#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE) #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) @@ -100,10 +102,10 @@ void arch_setup_new_exec(void); #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) #define _TIF_TSC_SIGSEGV (1 << TIF_TSC_SIGSEGV) -#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ +#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \ _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \ - _TIF_NOTIFY_SIGNAL) + _TIF_NOTIFY_SIGNAL | _TIF_SIGPENDING) #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index b260ddc4d3e9a..7993fab0cab4c 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -132,7 +132,7 @@ static void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) do { local_irq_enable(); - if (thread_flags & _TIF_NEED_RESCHED) + if (thread_flags & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)) schedule(); if (thread_flags & _TIF_UPROBE)