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um: Define timers on a per-CPU basis

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Define timers on a per-CPU basis to enable each CPU to have its
own timer. This is a preparation for adding SMP support.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027001815.1666872-5-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Tiwei Bie 2025-10-27 08:18:11 +08:00 committed by Johannes Berg
parent 2670917c2f
commit 9c82de55d4
6 changed files with 69 additions and 31 deletions
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3
arch/um/include/linux/time-internal.h
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@ -90,4 +90,7 @@ extern unsigned long tt_extra_sched_jiffies;
* which is intentional since we really shouldn't link it in that case.
*/
void time_travel_ndelay(unsigned long nsec);
int um_setup_timer(void);
#endif /* __TIMER_INTERNAL_H__ */

6
arch/um/include/shared/os.h
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@ -269,9 +269,9 @@ extern void os_warn(const char *fmt, ...)
/* time.c */
extern void os_idle_sleep(void);
extern int os_timer_create(void);
extern int os_timer_set_interval(unsigned long long nsecs);
extern int os_timer_one_shot(unsigned long long nsecs);
extern void os_timer_disable(void);
extern int os_timer_set_interval(int cpu, unsigned long long nsecs);
extern int os_timer_one_shot(int cpu, unsigned long long nsecs);
extern void os_timer_disable(int cpu);
extern long long os_persistent_clock_emulation(void);
extern long long os_nsecs(void);

2
arch/um/kernel/irq.c
View File

@ -683,7 +683,7 @@ void __init init_IRQ(void)
{
int i;
irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_edge_irq);
irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_percpu_irq);
for (i = 1; i < UM_LAST_SIGNAL_IRQ; i++)
irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);

58
arch/um/kernel/time.c
View File

@ -625,9 +625,10 @@ void time_travel_sleep(void)
* controller application.
*/
unsigned long long next = S64_MAX;
int cpu = raw_smp_processor_id();
if (time_travel_mode == TT_MODE_BASIC)
os_timer_disable();
os_timer_disable(cpu);
time_travel_update_time(next, true);
@ -638,9 +639,9 @@ void time_travel_sleep(void)
* This is somewhat wrong - we should get the first
* one sooner like the os_timer_one_shot() below...
*/
os_timer_set_interval(time_travel_timer_interval);
os_timer_set_interval(cpu, time_travel_timer_interval);
} else {
os_timer_one_shot(time_travel_timer_event.time - next);
os_timer_one_shot(cpu, time_travel_timer_event.time - next);
}
}
}
@ -758,6 +759,8 @@ extern u64 time_travel_ext_req(u32 op, u64 time);
#define time_travel_del_event(e) do { } while (0)
#endif
static struct clock_event_device timer_clockevent[NR_CPUS];
void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
{
unsigned long flags;
@ -780,12 +783,14 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
static int itimer_shutdown(struct clock_event_device *evt)
{
int cpu = evt - &timer_clockevent[0];
if (time_travel_mode != TT_MODE_OFF)
time_travel_del_event(&time_travel_timer_event);
if (time_travel_mode != TT_MODE_INFCPU &&
time_travel_mode != TT_MODE_EXTERNAL)
os_timer_disable();
os_timer_disable(cpu);
return 0;
}
@ -793,6 +798,7 @@ static int itimer_shutdown(struct clock_event_device *evt)
static int itimer_set_periodic(struct clock_event_device *evt)
{
unsigned long long interval = NSEC_PER_SEC / HZ;
int cpu = evt - &timer_clockevent[0];
if (time_travel_mode != TT_MODE_OFF) {
time_travel_del_event(&time_travel_timer_event);
@ -805,7 +811,7 @@ static int itimer_set_periodic(struct clock_event_device *evt)
if (time_travel_mode != TT_MODE_INFCPU &&
time_travel_mode != TT_MODE_EXTERNAL)
os_timer_set_interval(interval);
os_timer_set_interval(cpu, interval);
return 0;
}
@ -825,7 +831,7 @@ static int itimer_next_event(unsigned long delta,
if (time_travel_mode != TT_MODE_INFCPU &&
time_travel_mode != TT_MODE_EXTERNAL)
return os_timer_one_shot(delta);
return os_timer_one_shot(raw_smp_processor_id(), delta);
return 0;
}
@ -835,10 +841,9 @@ static int itimer_one_shot(struct clock_event_device *evt)
return itimer_next_event(0, evt);
}
static struct clock_event_device timer_clockevent = {
static struct clock_event_device _timer_clockevent = {
.name = "posix-timer",
.rating = 250,
.cpumask = cpu_possible_mask,
.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT,
.set_state_shutdown = itimer_shutdown,
@ -856,6 +861,9 @@ static struct clock_event_device timer_clockevent = {
static irqreturn_t um_timer(int irq, void *dev)
{
int cpu = raw_smp_processor_id();
struct clock_event_device *evt = &timer_clockevent[cpu];
/*
* Interrupt the (possibly) running userspace process, technically this
* should only happen if userspace is currently executing.
@ -867,7 +875,7 @@ static irqreturn_t um_timer(int irq, void *dev)
get_current()->mm)
os_alarm_process(get_current()->mm->context.id.pid);
(*timer_clockevent.event_handler)(&timer_clockevent);
evt->event_handler(evt);
return IRQ_HANDLED;
}
@ -904,7 +912,24 @@ static struct clocksource timer_clocksource = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init um_timer_setup(void)
int um_setup_timer(void)
{
int cpu = raw_smp_processor_id();
struct clock_event_device *evt = &timer_clockevent[cpu];
int err;
err = os_timer_create();
if (err)
return err;
memcpy(evt, &_timer_clockevent, sizeof(*evt));
evt->cpumask = cpumask_of(cpu);
clockevents_register_device(evt);
return 0;
}
static void __init um_timer_init(void)
{
int err;
@ -913,8 +938,8 @@ static void __init um_timer_setup(void)
printk(KERN_ERR "register_timer : request_irq failed - "
"errno = %d\n", -err);
err = os_timer_create();
if (err != 0) {
err = um_setup_timer();
if (err) {
printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
return;
}
@ -924,7 +949,6 @@ static void __init um_timer_setup(void)
printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
return;
}
clockevents_register_device(&timer_clockevent);
}
void read_persistent_clock64(struct timespec64 *ts)
@ -945,7 +969,7 @@ void read_persistent_clock64(struct timespec64 *ts)
void __init time_init(void)
{
timer_set_signal_handler();
late_time_init = um_timer_setup;
late_time_init = um_timer_init;
}
#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
@ -961,21 +985,21 @@ static int setup_time_travel(char *str)
{
if (strcmp(str, "=inf-cpu") == 0) {
time_travel_mode = TT_MODE_INFCPU;
timer_clockevent.name = "time-travel-timer-infcpu";
_timer_clockevent.name = "time-travel-timer-infcpu";
timer_clocksource.name = "time-travel-clock";
return 1;
}
if (strncmp(str, "=ext:", 5) == 0) {
time_travel_mode = TT_MODE_EXTERNAL;
timer_clockevent.name = "time-travel-timer-external";
_timer_clockevent.name = "time-travel-timer-external";
timer_clocksource.name = "time-travel-clock-external";
return time_travel_connect_external(str + 5);
}
if (!*str) {
time_travel_mode = TT_MODE_BASIC;
timer_clockevent.name = "time-travel-timer";
_timer_clockevent.name = "time-travel-timer";
timer_clocksource.name = "time-travel-clock";
return 1;
}

2
arch/um/os-Linux/main.c
View File

@ -171,7 +171,7 @@ int __init main(int argc, char **argv, char **envp)
*/
/* stop timers and set timer signal to be ignored */
os_timer_disable();
os_timer_disable(0);
/* disable SIGIO for the fds and set SIGIO to be ignored */
err = deactivate_all_fds();

29
arch/um/os-Linux/time.c
View File

@ -17,7 +17,7 @@
#include <string.h>
#include "internal.h"
static timer_t event_high_res_timer = 0;
static timer_t event_high_res_timer[CONFIG_NR_CPUS] = { 0 };
static inline long long timespec_to_ns(const struct timespec *ts)
{
@ -32,20 +32,30 @@ long long os_persistent_clock_emulation(void)
return timespec_to_ns(&realtime_tp);
}
#ifndef sigev_notify_thread_id
#define sigev_notify_thread_id _sigev_un._tid
#endif
/**
* os_timer_create() - create an new posix (interval) timer
*/
int os_timer_create(void)
{
timer_t *t = &event_high_res_timer;
timer_t *t = &event_high_res_timer[0];
struct sigevent sev = {
.sigev_notify = SIGEV_THREAD_ID,
.sigev_signo = SIGALRM,
.sigev_value.sival_ptr = t,
.sigev_notify_thread_id = gettid(),
};
if (timer_create(CLOCK_MONOTONIC, NULL, t) == -1)
if (timer_create(CLOCK_MONOTONIC, &sev, t) == -1)
return -1;
return 0;
}
int os_timer_set_interval(unsigned long long nsecs)
int os_timer_set_interval(int cpu, unsigned long long nsecs)
{
struct itimerspec its;
@ -55,13 +65,13 @@ int os_timer_set_interval(unsigned long long nsecs)
its.it_interval.tv_sec = nsecs / UM_NSEC_PER_SEC;
its.it_interval.tv_nsec = nsecs % UM_NSEC_PER_SEC;
if (timer_settime(event_high_res_timer, 0, &its, NULL) == -1)
if (timer_settime(event_high_res_timer[cpu], 0, &its, NULL) == -1)
return -errno;
return 0;
}
int os_timer_one_shot(unsigned long long nsecs)
int os_timer_one_shot(int cpu, unsigned long long nsecs)
{
struct itimerspec its = {
.it_value.tv_sec = nsecs / UM_NSEC_PER_SEC,
@ -71,19 +81,20 @@ int os_timer_one_shot(unsigned long long nsecs)
.it_interval.tv_nsec = 0, // we cheat here
};
timer_settime(event_high_res_timer, 0, &its, NULL);
timer_settime(event_high_res_timer[cpu], 0, &its, NULL);
return 0;
}
/**
* os_timer_disable() - disable the posix (interval) timer
* @cpu: the CPU for which the timer is to be disabled
*/
void os_timer_disable(void)
void os_timer_disable(int cpu)
{
struct itimerspec its;
memset(&its, 0, sizeof(struct itimerspec));
timer_settime(event_high_res_timer, 0, &its, NULL);
timer_settime(event_high_res_timer[cpu], 0, &its, NULL);
}
long long os_nsecs(void)