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Commit 0587d409 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/time: return with irqs disabled from psw_idle 



Modify the psw_idle waiting logic in entry[64].S to return with
interrupts disabled. This avoids potential issues with udelay
and interrupt loops as interrupts are not reenabled after
clock comparator interrupts.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 6b169ac9

arch/s390/kernel/entry.S

+2 −2
Original line number Diff line number Diff line
@@ -886,13 +886,13 @@ cleanup_idle: 
	stm	%r9,%r10,__LC_SYSTEM_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__TIMER_IDLE_EXIT(%r2)

	# prepare return psw

	n	%r8,BASED(cleanup_idle_wait)	# clear wait state bit

	n	%r8,BASED(cleanup_idle_wait)	# clear irq & wait state bits

	l	%r9,24(%r11)			# return from psw_idle

	br	%r14

cleanup_idle_insn:

	.long	psw_idle_lpsw + 0x80000000

cleanup_idle_wait:

	.long	0xfffdffff

	.long	0xfcfdffff



/*

 * Integer constants

arch/s390/kernel/entry64.S

+1 −1
Original line number Diff line number Diff line
@@ -929,7 +929,7 @@ cleanup_idle: 
	stg	%r9,__LC_SYSTEM_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__TIMER_IDLE_EXIT(%r2)

	# prepare return psw

	nihh	%r8,0xfffd		# clear wait state bit

	nihh	%r8,0xfcfd		# clear irq & wait state bits

	lg	%r9,48(%r11)		# return from psw_idle

	br	%r14

cleanup_idle_insn:

arch/s390/kernel/process.c

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ void arch_cpu_idle(void) 
	}

	/* Halt the cpu and keep track of cpu time accounting. */

	vtime_stop_cpu();

	local_irq_enable();

}



void arch_cpu_idle_exit(void)

arch/s390/kernel/time.c

+0 −1
Original line number Diff line number Diff line
@@ -92,7 +92,6 @@ void clock_comparator_work(void) 
	struct clock_event_device *cd;



	S390_lowcore.clock_comparator = -1ULL;

	set_clock_comparator(S390_lowcore.clock_comparator);

	cd = &__get_cpu_var(comparators);

	cd->event_handler(cd);

}

arch/s390/lib/delay.c

+0 −2
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ static void __udelay_disabled(unsigned long long usecs) 
	do {

		set_clock_comparator(end);

		vtime_stop_cpu();

		local_irq_disable();

	} while (get_tod_clock() < end);

	lockdep_on();

	__ctl_load(cr0, 0, 0);
@@ -64,7 +63,6 @@ static void __udelay_enabled(unsigned long long usecs) 
			set_clock_comparator(end);

		}

		vtime_stop_cpu();

		local_irq_disable();

		if (clock_saved)

			local_tick_enable(clock_saved);

	} while (get_tod_clock() < end);