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um: Implement ndelay/udelay in time-travel mode

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In external or inf-cpu time-travel mode, ndelay/udelay currently
just waste CPU time since the simulation time doesn't advance.
Implement them properly in this case.

Note that the "if (time_travel_mode == ...)" parts compile out
if CONFIG_UML_TIME_TRAVEL_SUPPORT isn't set, time_travel_mode is
defined to TT_MODE_OFF in that case.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Johannes Berg 2020-02-13 14:26:48 +01:00 committed by Richard Weinberger
parent 88ce642492
commit 0bc8fb4dda
4 changed files with 42 additions and 1 deletions
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1
arch/um/include/asm/Kbuild
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@ -3,7 +3,6 @@ generic-y += bpf_perf_event.h
generic-y += bug.h
generic-y += compat.h
generic-y += current.h
generic-y += delay.h
generic-y += device.h
generic-y += emergency-restart.h
generic-y += exec.h

30
arch/um/include/asm/delay.h Normal file
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@ -0,0 +1,30 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __UM_DELAY_H
#define __UM_DELAY_H
#include <asm-generic/delay.h>
#include <linux/time-internal.h>
static inline void um_ndelay(unsigned long nsecs)
{
if (time_travel_mode == TT_MODE_INFCPU ||
time_travel_mode == TT_MODE_EXTERNAL) {
time_travel_ndelay(nsecs);
return;
}
ndelay(nsecs);
}
#undef ndelay
#define ndelay um_ndelay
static inline void um_udelay(unsigned long usecs)
{
if (time_travel_mode == TT_MODE_INFCPU ||
time_travel_mode == TT_MODE_EXTERNAL) {
time_travel_ndelay(1000 * usecs);
return;
}
udelay(usecs);
}
#undef udelay
#define udelay um_udelay
#endif /* __UM_DELAY_H */

6
arch/um/include/linux/time-internal.h
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@ -75,4 +75,10 @@ static inline void time_travel_wait_readable(int fd)
{
}
#endif /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
/*
* Without CONFIG_UML_TIME_TRAVEL_SUPPORT this is a linker error if used,
* which is intentional since we really shouldn't link it in that case.
*/
void time_travel_ndelay(unsigned long nsec);
#endif /* __TIMER_INTERNAL_H__ */

6
arch/um/kernel/time.c
View File

@ -374,6 +374,12 @@ static void time_travel_update_time(unsigned long long next, bool idle)
time_travel_del_event(&ne);
}
void time_travel_ndelay(unsigned long nsec)
{
time_travel_update_time(time_travel_time + nsec, false);
}
EXPORT_SYMBOL(time_travel_ndelay);
void time_travel_add_irq_event(struct time_travel_event *e)
{
BUG_ON(time_travel_mode != TT_MODE_EXTERNAL);