Commit 40607ee9 authored by Peter Zijlstra (Intel)'s avatar Peter Zijlstra (Intel) Committed by Ingo Molnar
Browse files

preempt/dynamic: Provide irqentry_exit_cond_resched() static call 



Provide static call to control IRQ preemption (called in CONFIG_PREEMPT)
so that we can override its behaviour when preempt= is overriden.

Since the default behaviour is full preemption, its call is
initialized to provide IRQ preemption when preempt= isn't passed.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-8-frederic@kernel.org
parent 2c9a98d3

include/linux/entry-common.h

+4 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef __LINUX_ENTRYCOMMON_H

#define __LINUX_ENTRYCOMMON_H



#include <linux/static_call_types.h>

#include <linux/tracehook.h>

#include <linux/syscalls.h>

#include <linux/seccomp.h>
@@ -454,6 +455,9 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs); 
 * Conditional reschedule with additional sanity checks.

 */

void irqentry_exit_cond_resched(void);

#ifdef CONFIG_PREEMPT_DYNAMIC

DECLARE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);

#endif



/**

 * irqentry_exit - Handle return from exception that used irqentry_enter()

kernel/entry/common.c

+9 −1
Original line number Diff line number Diff line
@@ -385,6 +385,9 @@ void irqentry_exit_cond_resched(void) 
			preempt_schedule_irq();

	}

}

#ifdef CONFIG_PREEMPT_DYNAMIC

DEFINE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);

#endif



noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)

{
@@ -411,8 +414,13 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) 
		}



		instrumentation_begin();

		if (IS_ENABLED(CONFIG_PREEMPTION))

		if (IS_ENABLED(CONFIG_PREEMPTION)) {

#ifdef CONFIG_PREEMT_DYNAMIC

			static_call(irqentry_exit_cond_resched)();

#else

			irqentry_exit_cond_resched();

#endif

		}

		/* Covers both tracing and lockdep */

		trace_hardirqs_on();

		instrumentation_end();