b1cae1f84a
With commit 58c644ba512c ("sched/idle: Fix arch_cpu_idle() vs
tracing") common code calls arch_cpu_idle() with a lockdep state that
tells irqs are on.
This doesn't work very well for s390: psw_idle() will enable interrupts
to wait for an interrupt. As soon as an interrupt occurs the interrupt
handler will verify if the old context was psw_idle(). If that is the
case the interrupt enablement bits in the old program status word will
be cleared.
A subsequent test in both the external as well as the io interrupt
handler checks if in the old context interrupts were enabled. Due to
the above patching of the old program status word it is assumed the
old context had interrupts disabled, and therefore a call to
TRACE_IRQS_OFF (aka trace_hardirqs_off_caller) is skipped. Which in
turn makes lockdep incorrectly "think" that interrupts are enabled
within the interrupt handler.
Fix this by unconditionally calling TRACE_IRQS_OFF when entering
interrupt handlers. Also call unconditionally TRACE_IRQS_ON when
leaving interrupts handlers.
This leaves the special psw_idle() case, which now returns with
interrupts disabled, but has an "irqs on" lockdep state. So callers of
psw_idle() must adjust the state on their own, if required. This is
currently only __udelay_disabled().
Fixes: 58c644ba512c ("sched/idle: Fix arch_cpu_idle() vs tracing")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Precise Delay Loops for S390
|
|
*
|
|
* Copyright IBM Corp. 1999, 2008
|
|
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
|
|
* Heiko Carstens <heiko.carstens@de.ibm.com>,
|
|
*/
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/timex.h>
|
|
#include <linux/export.h>
|
|
#include <linux/irqflags.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/irq.h>
|
|
#include <asm/vtimer.h>
|
|
#include <asm/div64.h>
|
|
#include <asm/idle.h>
|
|
|
|
void __delay(unsigned long loops)
|
|
{
|
|
/*
|
|
* To end the bloody studid and useless discussion about the
|
|
* BogoMips number I took the liberty to define the __delay
|
|
* function in a way that that resulting BogoMips number will
|
|
* yield the megahertz number of the cpu. The important function
|
|
* is udelay and that is done using the tod clock. -- martin.
|
|
*/
|
|
asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
|
|
}
|
|
EXPORT_SYMBOL(__delay);
|
|
|
|
static void __udelay_disabled(unsigned long long usecs)
|
|
{
|
|
unsigned long cr0, cr0_new, psw_mask;
|
|
struct s390_idle_data idle;
|
|
u64 end;
|
|
|
|
end = get_tod_clock() + (usecs << 12);
|
|
__ctl_store(cr0, 0, 0);
|
|
cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
|
|
cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
|
|
__ctl_load(cr0_new, 0, 0);
|
|
psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
|
|
set_clock_comparator(end);
|
|
set_cpu_flag(CIF_IGNORE_IRQ);
|
|
psw_idle(&idle, psw_mask);
|
|
trace_hardirqs_off();
|
|
clear_cpu_flag(CIF_IGNORE_IRQ);
|
|
set_clock_comparator(S390_lowcore.clock_comparator);
|
|
__ctl_load(cr0, 0, 0);
|
|
}
|
|
|
|
static void __udelay_enabled(unsigned long long usecs)
|
|
{
|
|
u64 clock_saved, end;
|
|
|
|
end = get_tod_clock_fast() + (usecs << 12);
|
|
do {
|
|
clock_saved = 0;
|
|
if (tod_after(S390_lowcore.clock_comparator, end)) {
|
|
clock_saved = local_tick_disable();
|
|
set_clock_comparator(end);
|
|
}
|
|
enabled_wait();
|
|
if (clock_saved)
|
|
local_tick_enable(clock_saved);
|
|
} while (get_tod_clock_fast() < end);
|
|
}
|
|
|
|
/*
|
|
* Waits for 'usecs' microseconds using the TOD clock comparator.
|
|
*/
|
|
void __udelay(unsigned long long usecs)
|
|
{
|
|
unsigned long flags;
|
|
|
|
preempt_disable();
|
|
local_irq_save(flags);
|
|
if (in_irq()) {
|
|
__udelay_disabled(usecs);
|
|
goto out;
|
|
}
|
|
if (in_softirq()) {
|
|
if (raw_irqs_disabled_flags(flags))
|
|
__udelay_disabled(usecs);
|
|
else
|
|
__udelay_enabled(usecs);
|
|
goto out;
|
|
}
|
|
if (raw_irqs_disabled_flags(flags)) {
|
|
local_bh_disable();
|
|
__udelay_disabled(usecs);
|
|
_local_bh_enable();
|
|
goto out;
|
|
}
|
|
__udelay_enabled(usecs);
|
|
out:
|
|
local_irq_restore(flags);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(__udelay);
|
|
|
|
/*
|
|
* Simple udelay variant. To be used on startup and reboot
|
|
* when the interrupt handler isn't working.
|
|
*/
|
|
void udelay_simple(unsigned long long usecs)
|
|
{
|
|
u64 end;
|
|
|
|
end = get_tod_clock_fast() + (usecs << 12);
|
|
while (get_tod_clock_fast() < end)
|
|
cpu_relax();
|
|
}
|
|
|
|
void __ndelay(unsigned long long nsecs)
|
|
{
|
|
u64 end;
|
|
|
|
nsecs <<= 9;
|
|
do_div(nsecs, 125);
|
|
end = get_tod_clock_fast() + nsecs;
|
|
if (nsecs & ~0xfffUL)
|
|
__udelay(nsecs >> 12);
|
|
while (get_tod_clock_fast() < end)
|
|
barrier();
|
|
}
|
|
EXPORT_SYMBOL(__ndelay);
|