Commit 16824255 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by H. Peter Anvin
Browse files

x86, acpi, idle: Restructure the mwait idle routines 



People seem to delight in writing wrong and broken mwait idle routines;
collapse the lot.

This leaves mwait_play_dead() the sole remaining user of __mwait() and
new __mwait() users are probably doing it wrong.

Also remove __sti_mwait() as its unused.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jacob Jun Pan <jacob.jun.pan@linux.intel.com>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Len Brown <lenb@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Acked-by: default avatarRafael Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131212141654.616820819@infradead.org


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 40e2d7f9

arch/x86/include/asm/mwait.h

+40 −0
Original line number Diff line number Diff line 
#ifndef _ASM_X86_MWAIT_H

#define _ASM_X86_MWAIT_H



#include <linux/sched.h>



#define MWAIT_SUBSTATE_MASK		0xf

#define MWAIT_CSTATE_MASK		0xf

#define MWAIT_SUBSTATE_SIZE		4
@@ -13,4 +15,42 @@ 


#define MWAIT_ECX_INTERRUPT_BREAK	0x1



static inline void __monitor(const void *eax, unsigned long ecx,

			     unsigned long edx)

{

	/* "monitor %eax, %ecx, %edx;" */

	asm volatile(".byte 0x0f, 0x01, 0xc8;"

		     :: "a" (eax), "c" (ecx), "d"(edx));

}



static inline void __mwait(unsigned long eax, unsigned long ecx)

{

	/* "mwait %eax, %ecx;" */

	asm volatile(".byte 0x0f, 0x01, 0xc9;"

		     :: "a" (eax), "c" (ecx));

}



/*

 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,

 * which can obviate IPI to trigger checking of need_resched.

 * We execute MONITOR against need_resched and enter optimized wait state

 * through MWAIT. Whenever someone changes need_resched, we would be woken

 * up from MWAIT (without an IPI).

 *

 * New with Core Duo processors, MWAIT can take some hints based on CPU

 * capability.

 */

static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)

{

	if (!current_set_polling_and_test()) {

		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))

			clflush((void *)&current_thread_info()->flags);



		__monitor((void *)&current_thread_info()->flags, 0, 0);

		if (!need_resched())

			__mwait(eax, ecx);

	}

	__current_clr_polling();

}



#endif /* _ASM_X86_MWAIT_H */

arch/x86/include/asm/processor.h

+0 −23
Original line number Diff line number Diff line
@@ -700,29 +700,6 @@ static inline void sync_core(void) 
#endif

}



static inline void __monitor(const void *eax, unsigned long ecx,

			     unsigned long edx)

{

	/* "monitor %eax, %ecx, %edx;" */

	asm volatile(".byte 0x0f, 0x01, 0xc8;"

		     :: "a" (eax), "c" (ecx), "d"(edx));

}



static inline void __mwait(unsigned long eax, unsigned long ecx)

{

	/* "mwait %eax, %ecx;" */

	asm volatile(".byte 0x0f, 0x01, 0xc9;"

		     :: "a" (eax), "c" (ecx));

}



static inline void __sti_mwait(unsigned long eax, unsigned long ecx)

{

	trace_hardirqs_on();

	/* "mwait %eax, %ecx;" */

	asm volatile("sti; .byte 0x0f, 0x01, 0xc9;"

		     :: "a" (eax), "c" (ecx));

}



extern void select_idle_routine(const struct cpuinfo_x86 *c);

extern void init_amd_e400_c1e_mask(void);

arch/x86/kernel/acpi/cstate.c

+0 −23
Original line number Diff line number Diff line
@@ -150,29 +150,6 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu, 
}

EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);



/*

 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,

 * which can obviate IPI to trigger checking of need_resched.

 * We execute MONITOR against need_resched and enter optimized wait state

 * through MWAIT. Whenever someone changes need_resched, we would be woken

 * up from MWAIT (without an IPI).

 *

 * New with Core Duo processors, MWAIT can take some hints based on CPU

 * capability.

 */

void mwait_idle_with_hints(unsigned long ax, unsigned long cx)

{

	if (!need_resched()) {

		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))

			clflush((void *)&current_thread_info()->flags);



		__monitor((void *)&current_thread_info()->flags, 0, 0);

		smp_mb();

		if (!need_resched())

			__mwait(ax, cx);

	}

}



void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)

{

	unsigned int cpu = smp_processor_id();

drivers/acpi/acpi_pad.c

+1 −4
Original line number Diff line number Diff line
@@ -193,10 +193,7 @@ static int power_saving_thread(void *data) 
					CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);

			stop_critical_timings();



			__monitor((void *)&current_thread_info()->flags, 0, 0);

			smp_mb();

			if (!need_resched())

				__mwait(power_saving_mwait_eax, 1);

			mwait_idle_with_hints(power_saving_mwait_eax, 1);



			start_critical_timings();

			if (lapic_marked_unstable)

drivers/acpi/processor_idle.c

+0 −15
Original line number Diff line number Diff line
@@ -727,11 +727,6 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev, 
	if (unlikely(!pr))

		return -EINVAL;



	if (cx->entry_method == ACPI_CSTATE_FFH) {

		if (current_set_polling_and_test())

			return -EINVAL;

	}



	lapic_timer_state_broadcast(pr, cx, 1);

	acpi_idle_do_entry(cx);
@@ -785,11 +780,6 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev, 
	if (unlikely(!pr))

		return -EINVAL;



	if (cx->entry_method == ACPI_CSTATE_FFH) {

		if (current_set_polling_and_test())

			return -EINVAL;

	}



	/*

	 * Must be done before busmaster disable as we might need to

	 * access HPET !
@@ -841,11 +831,6 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev, 
		}

	}



	if (cx->entry_method == ACPI_CSTATE_FFH) {

		if (current_set_polling_and_test())

			return -EINVAL;

	}



	acpi_unlazy_tlb(smp_processor_id());



	/* Tell the scheduler that we are going deep-idle: */

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