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Thu, 12 Jan 2023 20:57:07 +0100 (CET) Message-ID: <20230112195540.618076436@infradead.org> User-Agent: quilt/0.66 Date: Thu, 12 Jan 2023 20:43:35 +0100 From: Peter Zijlstra To: peterz@infradead.org Cc: richard.henderson@linaro.org, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, nsekhar@ti.com, brgl@bgdev.pl, 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, krzysztof.kozlowski@linaro.org, alim.akhtar@samsung.com, 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, npiggin@gmail.com, christophe.leroy@csgroup.eu, 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, mark.rutland@arm.com, 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, andersson@kernel.org, konrad.dybcio@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, atishp@atishpatra.org, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, dennis@kernel.org, tj@kernel.org, cl@linux.com, rostedt@goodmis.org, mhiramat@kernel.org, frederic@kernel.org, paulmck@kernel.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, Andrew Morton , jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-omap@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, 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, 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, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, kasan-dev@googlegroups.com, "Gautham R. Shenoy" , "Rafael J. Wysocki" , Ulf Hansson Subject: [PATCH v3 21/51] arch/idle: Change arch_cpu_idle() IRQ behaviour References: <20230112194314.845371875@infradead.org> MIME-Version: 1.0 X-Mailman-Approved-At: Thu, 12 Jan 2023 13:49:35 -0800 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: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org 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) Reviewed-by: Gautham R. Shenoy Acked-by: Mark Rutland [arm64] Acked-by: Rafael J. Wysocki Acked-by: Guo Ren Acked-by: Frederic Weisbecker Tested-by: Tony Lindgren Tested-by: Ulf Hansson --- 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/loongarch/kernel/idle.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 -- 27 files changed, 29 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 @@ -100,6 +100,5 @@ 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 @@ -309,7 +309,7 @@ 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 @@ -242,6 +242,7 @@ void arch_cpu_idle(void) (*mark_idle)(1); raw_safe_halt(); + raw_local_irq_disable(); if (mark_idle) (*mark_idle)(0); --- a/arch/loongarch/kernel/idle.c +++ b/arch/loongarch/kernel/idle.c @@ -13,4 +13,5 @@ void __cpuidle arch_cpu_idle(void) { raw_local_irq_enable(); __arch_cpu_idle(); /* idle instruction needs irq enabled */ + raw_local_irq_disable(); } --- a/arch/microblaze/kernel/process.c +++ b/arch/microblaze/kernel/process.c @@ -140,5 +140,4 @@ 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 @@ -217,7 +217,6 @@ 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 @@ -223,6 +223,9 @@ 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 int read_msr(struct pt_regs *regs, struct ve_info *ve) --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -701,6 +701,7 @@ 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); @@ -806,13 +807,7 @@ 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(); } /* @@ -870,12 +865,10 @@ 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) ct_cpuidle_enter(); arch_cpu_idle(); - raw_local_irq_disable(); ct_cpuidle_exit(); start_critical_timings();