arch/idle: Change arch_cpu_idle() behavior: always exit with IRQs disabled

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) <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Tested-by: Tony Lindgren <[e-mail]>
Tested-by: Ulf Hansson <[e-mail]>
Reviewed-by: Gautham R. Shenoy <[e-mail]>
Acked-by: Mark Rutland <[e-mail]> [arm64]
Acked-by: Rafael J. Wysocki <[e-mail]>
Acked-by: Guo Ren <[e-mail]>
Acked-by: Frederic Weisbecker <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/alpha/kernel/process.c

···
 void arch_cpu_idle(void)
 {
 	wtint(0);
-	raw_local_irq_enable();
 }
 
 void arch_cpu_idle_dead(void)

arch/arc/kernel/process.c

···
 		"sleep %0	\n"
 		:
 		:"I"(arg)); /* can't be "r" has to be embedded const */
+
+	raw_local_irq_disable();
 }
 
 #else	/* ARC700 */
···
 {
 	/* sleep, but enable both set E1/E2 (levels of interrupts) before committing */
 	__asm__ __volatile__("sleep 0x3	\n");
+	raw_local_irq_disable();
 }
 
 #endif

arch/arm/kernel/process.c

···
 		arm_pm_idle();
 	else
 		cpu_do_idle();
-	raw_local_irq_enable();
 }
 
 void arch_cpu_idle_prepare(void)

arch/arm/mach-gemini/board-dt.c

···
 	 */
 
 	/* 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)

arch/arm64/kernel/idle.c

···
 	 * tricks
 	 */
 	cpu_do_idle();
-	raw_local_irq_enable();
 }

arch/csky/kernel/process.c

···
 #ifdef CONFIG_CPU_PM_STOP
 	asm volatile("stop\n");
 #endif
-	raw_local_irq_enable();
 }
 #endif

arch/csky/kernel/smp.c

···
 	while (!secondary_stack)
 		arch_cpu_idle();
 
-	local_irq_disable();
+	raw_local_irq_disable();
 
 	asm volatile(
 		"mov	sp, %0\n"

arch/hexagon/kernel/process.c

···
 {
 	__vmwait();
 	/*  interrupts wake us up, but irqs are still disabled */
-	raw_local_irq_enable();
 }
 
 /*

arch/ia64/kernel/process.c

···
 		(*mark_idle)(1);
 
 	raw_safe_halt();
+	raw_local_irq_disable();
 
 	if (mark_idle)
 		(*mark_idle)(0);

arch/loongarch/kernel/idle.c

···
 {
 	raw_local_irq_enable();
 	__arch_cpu_idle(); /* idle instruction needs irq enabled */
+	raw_local_irq_disable();
 }

arch/microblaze/kernel/process.c

···
 
 void arch_cpu_idle(void)
 {
-       raw_local_irq_enable();
 }

arch/mips/kernel/idle.c

···
 {
 	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();
 }
 
 /*
···
 		"	.set	arch=r4000	\n"
 		"	wait			\n"
 		"	.set	pop		\n");
-	raw_local_irq_enable();
 }
 
 /*
···
 		"	wait						\n"
 		"	mtc0	$1, $12		# stalls until W stage	\n"
 		"	.set	pop					\n");
-	raw_local_irq_enable();
 }
 
 /*
···
 	"	nop				\n"
 	"	.set	pop			\n"
 	: : "r" (au1k_wait), "r" (c0status));
+
+	raw_local_irq_disable();
 }
 
 static int __initdata nowait;
···
 {
 	if (cpu_wait)
 		cpu_wait();
-	else
-		raw_local_irq_enable();
 }
 
 #ifdef CONFIG_CPU_IDLE

arch/nios2/kernel/process.c

···
 
 void arch_cpu_idle(void)
 {
-	raw_local_irq_enable();
 }
 
 /*

arch/openrisc/kernel/process.c

···
 	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;

arch/parisc/kernel/process.c

···
 
 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":::);
 }

arch/powerpc/kernel/idle.c

···
 		 * 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.

arch/riscv/kernel/process.c

···
 void arch_cpu_idle(void)
 {
 	cpu_do_idle();
-	raw_local_irq_enable();
 }
 
 void __show_regs(struct pt_regs *regs)

arch/s390/kernel/idle.c

···
 	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,

arch/sh/kernel/idle.c

···
 	raw_local_irq_enable();
 	/* Isn't this racy ? */
 	cpu_sleep();
+	raw_local_irq_disable();
 	clear_bl_bit();
 }
 

arch/sparc/kernel/leon_pmc.c

···
 		"lda	[%0] %1, %%g0\n"
 		:
 		: "r"(address), "i"(ASI_LEON_BYPASS));
+
+	raw_local_irq_disable();
 }
 
 /*
···
 
 	/* 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 */

arch/sparc/kernel/process_32.c

···
 {
 	if (sparc_idle)
 		(*sparc_idle)();
-	raw_local_irq_enable();
 }
 
 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */

arch/sparc/kernel/process_64.c

···
 {
 	if (tlb_type != hypervisor) {
 		touch_nmi_watchdog();
-		raw_local_irq_enable();
 	} else {
 		unsigned long pstate;
 
···
 			"wrpr %0, %%g0, %%pstate"
 			: "=&r" (pstate)
 			: "i" (PSTATE_IE));
+
+		raw_local_irq_disable();
 	}
 }
 

arch/um/kernel/process.c

···
 {
 	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 	um_idle_sleep();
-	raw_local_irq_enable();
 }
 
 int __cant_sleep(void) {

arch/x86/coco/tdx/tdx.c

···
 	 */
 	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)

arch/x86/kernel/process.c

···
 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);
···
 
 	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();
 }
 
 /*
···
 		}
 
 		__monitor((void *)&current_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();
 }

arch/xtensa/kernel/process.c

···
 void arch_cpu_idle(void)
 {
 	platform_idle();
+	raw_local_irq_disable();
 }
 
 /*

kernel/sched/idle.c

···
 void __weak arch_cpu_idle(void)
 {
 	cpu_idle_force_poll = 1;
-	raw_local_irq_enable();
 }
 
 /**
···
 
 		ct_cpuidle_enter();
 		arch_cpu_idle();
-		raw_local_irq_disable();
 		ct_cpuidle_exit();
 
 		start_critical_timings();