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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83790C43334 for ; Tue, 14 Jun 2022 16:22:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242212AbiFNQWb (ORCPT ); Tue, 14 Jun 2022 12:22:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237661AbiFNQW0 (ORCPT ); Tue, 14 Jun 2022 12:22:26 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 52BA4DF8; Tue, 14 Jun 2022 09:22:24 -0700 (PDT) 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 E098B169E; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > 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 BFF43CCA485 for ; Tue, 14 Jun 2022 16:22:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: 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: List-Owner; bh=MxUbKjBJKub9aTD5lq/2amjj2Ch93aJtBq80IkQqnt0=; b=qxTeLrnbFdQS2D yq2fCJ4mdfHt+MTphawyNmB1ySx5buuwbaoqljdKGmHX9XfJuYWI6avMPEZNcnF4mInnNkSBLZtTw TZh3CG2IuRGAr7vGaDJrFIYya9azowo3qjPh8iJvuIeuIr68AXFxJlmyWptAXjFev4YiZr5hB62pw /UT7QYB+onDWUZWJuQ2svZBQFFAotjqOeaI2gPPcyYIuP/cfXDKknQRAPkNnK+aK5nXouhNAm6heo 8M+LJ0/QOzbVlXlkXlW3eA5M89KzeQbscZo9uHEi/a3QFUIj07FRdm/cu8sbaX1ywU6BOTMZFX0PX 7TImOMkbnEzImxRhrUZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o19JF-00AJmd-M0; Tue, 14 Jun 2022 16:22:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o19JB-00AJks-Ez; Tue, 14 Jun 2022 16:22:27 +0000 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 DFB341692; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220614_092225_647161_F0029F93 X-CRM114-Status: GOOD ( 27.80 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc 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 smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 833F8C43334 for ; Tue, 14 Jun 2022 16:22:29 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 14C7D83339; Tue, 14 Jun 2022 16:22:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id KV5JsxnGX_2e; Tue, 14 Jun 2022 16:22:27 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp1.osuosl.org (Postfix) with ESMTPS id 4B0B58333F; Tue, 14 Jun 2022 16:22:27 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0C96EC0039; Tue, 14 Jun 2022 16:22:27 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0295FC002D for ; Tue, 14 Jun 2022 16:22:26 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id D452A40B70 for ; Tue, 14 Jun 2022 16:22:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id hgwJRLMe75Gl for ; Tue, 14 Jun 2022 16:22:24 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp2.osuosl.org (Postfix) with ESMTP id A08E140B65 for ; Tue, 14 Jun 2022 16:22:24 +0000 (UTC) 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 DFB341692; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> Cc: juri.lelli@redhat.com, rafael@kernel.org, benh@kernel.crashing.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualization@lists.linux-foundation.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, khilman@kernel.org, linux-csky@vger.kernel.org, pv-drivers@vmware.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, Arnd Bergmann , ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, paulmck@kernel.org, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization 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 4EE02C43334 for ; Tue, 14 Jun 2022 16:43:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: 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: List-Owner; bh=xpmQ5VQ4txFOnMTtApzEJNTITXM5ATjPRipHXTaE3bM=; b=Xxzgtas77tDLOe s+8UliYHbs9pTBScgkDB4eHdNMlbbFwvBQKKZKgbR/+ANncZoWfLebgwt/sz4GmpZmXNxi0ghy/gK 5HBmHeRFMiIx64heVrCf6LjV1ZNtvSKqjgqJoOk7bIgZDJa6/+OEJRugPTJfWuIUa9Kh/Om71GlHA FhjuG06JZv3qlapq/l1bYkpryvRlOZmmiO2AYPvVTMEPBLkKZ0iUw5jdsxOCJytsOZFIMsBUMF7ri oYV12+qV2pYlEJ4mQk2zF/PGKZKDb24MZTXz7hFYU//ZKq1cqUHaGE2T+gju0hxNpoW3riPQ42Q7H 3IS3kqEt+vI1NJoBNfMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o19de-00AP3R-UF; Tue, 14 Jun 2022 16:43:34 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o19JB-00AJks-Ez; Tue, 14 Jun 2022 16:22:27 +0000 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 DFB341692; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220614_092225_647161_F0029F93 X-CRM114-Status: GOOD ( 27.80 ) X-Mailman-Approved-At: Tue, 14 Jun 2022 09:43:33 -0700 X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 mail.librecores.org (lists.librecores.org [88.198.125.70]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7E84CCA480 for ; Tue, 14 Jun 2022 20:01:59 +0000 (UTC) Received: from [172.31.1.100] (localhost.localdomain [127.0.0.1]) by mail.librecores.org (Postfix) with ESMTP id 16C6E249AB; Tue, 14 Jun 2022 22:01:59 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mail.librecores.org (Postfix) with ESMTP id AB43024940 for ; Tue, 14 Jun 2022 18:22:24 +0200 (CEST) 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 DFB341692; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> X-Mailman-Approved-At: Tue, 14 Jun 2022 22:01:55 +0200 X-BeenThere: openrisc@lists.librecores.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Discussion around the OpenRISC processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: juri.lelli@redhat.com, rafael@kernel.org, benh@kernel.crashing.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualization@lists.linux-foundation.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, khilman@kernel.org, linux-csky@vger.kernel.org, pv-drivers@vmware.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, Arnd Bergmann , ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, paulmck@kernel.org, hca@linux.ibm.com, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: openrisc-bounces@lists.librecores.org Sender: "OpenRISC" On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 84C3DCCA47A for ; Tue, 14 Jun 2022 22:12:32 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LN2jq0fBdz3g4l for ; Wed, 15 Jun 2022 08:12:31 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=mark.rutland@arm.com; receiver=) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4LMtyS25XWz3bpF for ; Wed, 15 Jun 2022 02:22:54 +1000 (AEST) 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 DFB341692; Tue, 14 Jun 2022 09:22:23 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.41.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 113C43F66F; Tue, 14 Jun 2022 09:22:05 -0700 (PDT) Date: Tue, 14 Jun 2022 17:22:02 +0100 From: Mark Rutland To: Peter Zijlstra Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> X-Mailman-Approved-At: Wed, 15 Jun 2022 08:01:46 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: juri.lelli@redhat.com, rafael@kernel.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualization@lists.linux-foundati on.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, khilman@kernel.org, linux-csky@vger.kernel.org, pv-drivers@vmware.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de , jacob.jun.pan@linux.intel.com, Arnd Bergmann , ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, paulmck@kernel.org, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfa ult.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Date: Tue, 14 Jun 2022 16:22:02 +0000 Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Message-Id: List-Id: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> In-Reply-To: <20220608144517.188449351@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Date: Tue, 14 Jun 2022 17:22:02 +0100 Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.188449351@infradead.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20220608144517.188449351@infradead.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, ao On Wed, Jun 08, 2022 at 04:27:43PM +0200, Peter Zijlstra wrote: > Current arch_cpu_idle() is called with IRQs disabled, but will return > with IRQs enabled. > > However, the very first thing the generic code does after calling > arch_cpu_idle() is raw_local_irq_disable(). This means that > architectures that can idle with IRQs disabled end up doing a > pointless 'enable-disable' dance. > > Therefore, push this IRQ disabling into the idle function, meaning > that those architectures can avoid the pointless IRQ state flipping. > > Signed-off-by: Peter Zijlstra (Intel) Nice! Acked-by: Mark Rutland [arm64] Mark. > --- > arch/alpha/kernel/process.c | 1 - > arch/arc/kernel/process.c | 3 +++ > arch/arm/kernel/process.c | 1 - > arch/arm/mach-gemini/board-dt.c | 3 ++- > arch/arm64/kernel/idle.c | 1 - > arch/csky/kernel/process.c | 1 - > arch/csky/kernel/smp.c | 2 +- > arch/hexagon/kernel/process.c | 1 - > arch/ia64/kernel/process.c | 1 + > arch/microblaze/kernel/process.c | 1 - > arch/mips/kernel/idle.c | 8 +++----- > arch/nios2/kernel/process.c | 1 - > arch/openrisc/kernel/process.c | 1 + > arch/parisc/kernel/process.c | 2 -- > arch/powerpc/kernel/idle.c | 5 ++--- > arch/riscv/kernel/process.c | 1 - > arch/s390/kernel/idle.c | 1 - > arch/sh/kernel/idle.c | 1 + > arch/sparc/kernel/leon_pmc.c | 4 ++++ > arch/sparc/kernel/process_32.c | 1 - > arch/sparc/kernel/process_64.c | 3 ++- > arch/um/kernel/process.c | 1 - > arch/x86/coco/tdx/tdx.c | 3 +++ > arch/x86/kernel/process.c | 15 ++++----------- > arch/xtensa/kernel/process.c | 1 + > kernel/sched/idle.c | 2 -- > 26 files changed, 28 insertions(+), 37 deletions(-) > > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -57,7 +57,6 @@ EXPORT_SYMBOL(pm_power_off); > void arch_cpu_idle(void) > { > wtint(0); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_dead(void) > --- a/arch/arc/kernel/process.c > +++ b/arch/arc/kernel/process.c > @@ -114,6 +114,8 @@ void arch_cpu_idle(void) > "sleep %0 \n" > : > :"I"(arg)); /* can't be "r" has to be embedded const */ > + > + raw_local_irq_disable(); > } > > #else /* ARC700 */ > @@ -122,6 +124,7 @@ void arch_cpu_idle(void) > { > /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ > __asm__ __volatile__("sleep 0x3 \n"); > + raw_local_irq_disable(); > } > > #endif > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -78,7 +78,6 @@ void arch_cpu_idle(void) > arm_pm_idle(); > else > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void arch_cpu_idle_prepare(void) > --- a/arch/arm/mach-gemini/board-dt.c > +++ b/arch/arm/mach-gemini/board-dt.c > @@ -42,8 +42,9 @@ static void gemini_idle(void) > */ > > /* FIXME: Enabling interrupts here is racy! */ > - local_irq_enable(); > + raw_local_irq_enable(); > cpu_do_idle(); > + raw_local_irq_disable(); > } > > static void __init gemini_init_machine(void) > --- a/arch/arm64/kernel/idle.c > +++ b/arch/arm64/kernel/idle.c > @@ -42,5 +42,4 @@ void noinstr arch_cpu_idle(void) > * tricks > */ > cpu_do_idle(); > - raw_local_irq_enable(); > } > --- a/arch/csky/kernel/process.c > +++ b/arch/csky/kernel/process.c > @@ -101,6 +101,5 @@ void arch_cpu_idle(void) > #ifdef CONFIG_CPU_PM_STOP > asm volatile("stop\n"); > #endif > - raw_local_irq_enable(); > } > #endif > --- a/arch/csky/kernel/smp.c > +++ b/arch/csky/kernel/smp.c > @@ -314,7 +314,7 @@ void arch_cpu_idle_dead(void) > while (!secondary_stack) > arch_cpu_idle(); > > - local_irq_disable(); > + raw_local_irq_disable(); > > asm volatile( > "mov sp, %0\n" > --- a/arch/hexagon/kernel/process.c > +++ b/arch/hexagon/kernel/process.c > @@ -44,7 +44,6 @@ void arch_cpu_idle(void) > { > __vmwait(); > /* interrupts wake us up, but irqs are still disabled */ > - raw_local_irq_enable(); > } > > /* > --- a/arch/ia64/kernel/process.c > +++ b/arch/ia64/kernel/process.c > @@ -241,6 +241,7 @@ void arch_cpu_idle(void) > (*mark_idle)(1); > > raw_safe_halt(); > + raw_local_irq_disable(); > > if (mark_idle) > (*mark_idle)(0); > --- a/arch/microblaze/kernel/process.c > +++ b/arch/microblaze/kernel/process.c > @@ -138,5 +138,4 @@ int dump_fpu(struct pt_regs *regs, elf_f > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > --- a/arch/mips/kernel/idle.c > +++ b/arch/mips/kernel/idle.c > @@ -33,13 +33,13 @@ static void __cpuidle r3081_wait(void) > { > unsigned long cfg = read_c0_conf(); > write_c0_conf(cfg | R30XX_CONF_HALT); > - raw_local_irq_enable(); > } > > void __cpuidle r4k_wait(void) > { > raw_local_irq_enable(); > __r4k_wait(); > + raw_local_irq_disable(); > } > > /* > @@ -57,7 +57,6 @@ void __cpuidle r4k_wait_irqoff(void) > " .set arch=r4000 \n" > " wait \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -77,7 +76,6 @@ static void __cpuidle rm7k_wait_irqoff(v > " wait \n" > " mtc0 $1, $12 # stalls until W stage \n" > " .set pop \n"); > - raw_local_irq_enable(); > } > > /* > @@ -103,6 +101,8 @@ static void __cpuidle au1k_wait(void) > " nop \n" > " .set pop \n" > : : "r" (au1k_wait), "r" (c0status)); > + > + raw_local_irq_disable(); > } > > static int __initdata nowait; > @@ -245,8 +245,6 @@ void arch_cpu_idle(void) > { > if (cpu_wait) > cpu_wait(); > - else > - raw_local_irq_enable(); > } > > #ifdef CONFIG_CPU_IDLE > --- a/arch/nios2/kernel/process.c > +++ b/arch/nios2/kernel/process.c > @@ -33,7 +33,6 @@ EXPORT_SYMBOL(pm_power_off); > > void arch_cpu_idle(void) > { > - raw_local_irq_enable(); > } > > /* > --- a/arch/openrisc/kernel/process.c > +++ b/arch/openrisc/kernel/process.c > @@ -102,6 +102,7 @@ void arch_cpu_idle(void) > raw_local_irq_enable(); > if (mfspr(SPR_UPR) & SPR_UPR_PMP) > mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME); > + raw_local_irq_disable(); > } > > void (*pm_power_off)(void) = NULL; > --- a/arch/parisc/kernel/process.c > +++ b/arch/parisc/kernel/process.c > @@ -187,8 +187,6 @@ void arch_cpu_idle_dead(void) > > void __cpuidle arch_cpu_idle(void) > { > - raw_local_irq_enable(); > - > /* nop on real hardware, qemu will idle sleep. */ > asm volatile("or %%r10,%%r10,%%r10\n":::); > } > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -51,10 +51,9 @@ void arch_cpu_idle(void) > * Some power_save functions return with > * interrupts enabled, some don't. > */ > - if (irqs_disabled()) > - raw_local_irq_enable(); > + if (!irqs_disabled()) > + raw_local_irq_disable(); > } else { > - raw_local_irq_enable(); > /* > * Go into low thread priority and possibly > * low power mode. > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -39,7 +39,6 @@ extern asmlinkage void ret_from_kernel_t > void arch_cpu_idle(void) > { > cpu_do_idle(); > - raw_local_irq_enable(); > } > > void __show_regs(struct pt_regs *regs) > --- a/arch/s390/kernel/idle.c > +++ b/arch/s390/kernel/idle.c > @@ -66,7 +66,6 @@ void arch_cpu_idle(void) > idle->idle_count++; > account_idle_time(cputime_to_nsecs(idle_time)); > raw_write_seqcount_end(&idle->seqcount); > - raw_local_irq_enable(); > } > > static ssize_t show_idle_count(struct device *dev, > --- a/arch/sh/kernel/idle.c > +++ b/arch/sh/kernel/idle.c > @@ -25,6 +25,7 @@ void default_idle(void) > raw_local_irq_enable(); > /* Isn't this racy ? */ > cpu_sleep(); > + raw_local_irq_disable(); > clear_bl_bit(); > } > > --- a/arch/sparc/kernel/leon_pmc.c > +++ b/arch/sparc/kernel/leon_pmc.c > @@ -57,6 +57,8 @@ static void pmc_leon_idle_fixup(void) > "lda [%0] %1, %%g0\n" > : > : "r"(address), "i"(ASI_LEON_BYPASS)); > + > + raw_local_irq_disable(); > } > > /* > @@ -70,6 +72,8 @@ static void pmc_leon_idle(void) > > /* For systems without power-down, this will be no-op */ > __asm__ __volatile__ ("wr %g0, %asr19\n\t"); > + > + raw_local_irq_disable(); > } > > /* Install LEON Power Down function */ > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -71,7 +71,6 @@ void arch_cpu_idle(void) > { > if (sparc_idle) > (*sparc_idle)(); > - raw_local_irq_enable(); > } > > /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */ > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -59,7 +59,6 @@ void arch_cpu_idle(void) > { > if (tlb_type != hypervisor) { > touch_nmi_watchdog(); > - raw_local_irq_enable(); > } else { > unsigned long pstate; > > @@ -90,6 +89,8 @@ void arch_cpu_idle(void) > "wrpr %0, %%g0, %%pstate" > : "=&r" (pstate) > : "i" (PSTATE_IE)); > + > + raw_local_irq_disable(); > } > } > > --- a/arch/um/kernel/process.c > +++ b/arch/um/kernel/process.c > @@ -216,7 +216,6 @@ void arch_cpu_idle(void) > { > cpu_tasks[current_thread_info()->cpu].pid = os_getpid(); > um_idle_sleep(); > - raw_local_irq_enable(); > } > > int __cant_sleep(void) { > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -178,6 +178,9 @@ void __cpuidle tdx_safe_halt(void) > */ > if (__halt(irq_disabled, do_sti)) > WARN_ONCE(1, "HLT instruction emulation failed\n"); > + > + /* XXX I can't make sense of what @do_sti actually does */ > + raw_local_irq_disable(); > } > > static bool read_msr(struct pt_regs *regs) > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -699,6 +699,7 @@ EXPORT_SYMBOL(boot_option_idle_override) > void __cpuidle default_idle(void) > { > raw_safe_halt(); > + raw_local_irq_disable(); > } > #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) > EXPORT_SYMBOL(default_idle); > @@ -804,13 +805,7 @@ static void amd_e400_idle(void) > > default_idle(); > > - /* > - * The switch back from broadcast mode needs to be called with > - * interrupts disabled. > - */ > - raw_local_irq_disable(); > tick_broadcast_exit(); > - raw_local_irq_enable(); > } > > /* > @@ -849,12 +844,10 @@ static __cpuidle void mwait_idle(void) > } > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (!need_resched()) > + if (!need_resched()) { > __sti_mwait(0, 0); > - else > - raw_local_irq_enable(); > - } else { > - raw_local_irq_enable(); > + raw_local_irq_disable(); > + } > } > __current_clr_polling(); > } > --- a/arch/xtensa/kernel/process.c > +++ b/arch/xtensa/kernel/process.c > @@ -183,6 +183,7 @@ void coprocessor_flush_release_all(struc > void arch_cpu_idle(void) > { > platform_idle(); > + raw_local_irq_disable(); > } > > /* > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -79,7 +79,6 @@ void __weak arch_cpu_idle_dead(void) { } > void __weak arch_cpu_idle(void) > { > cpu_idle_force_poll = 1; > - raw_local_irq_enable(); > } > > /** > @@ -96,7 +95,6 @@ void __cpuidle default_idle_call(void) > > cpuidle_rcu_enter(); > arch_cpu_idle(); > - raw_local_irq_disable(); > cpuidle_rcu_exit(); > > start_critical_timings(); > >