diff options
Diffstat (limited to 'arch/um/kernel/time.c')
| -rw-r--r-- | arch/um/kernel/time.c | 131 |
1 files changed, 124 insertions, 7 deletions
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c index 0c572a48158e..6a051b078359 100644 --- a/arch/um/kernel/time.c +++ b/arch/um/kernel/time.c @@ -19,11 +19,29 @@ #include <kern_util.h> #include <os.h> #include <timer-internal.h> +#include <shared/init.h> + +#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT +enum time_travel_mode time_travel_mode; +unsigned long long time_travel_time; +enum time_travel_timer_mode time_travel_timer_mode; +unsigned long long time_travel_timer_expiry; +unsigned long long time_travel_timer_interval; + +static bool time_travel_start_set; +static unsigned long long time_travel_start; +#else +#define time_travel_start_set 0 +#define time_travel_start 0 +#endif void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) { unsigned long flags; + if (time_travel_mode != TT_MODE_OFF) + time_travel_set_time(time_travel_timer_expiry); + local_irq_save(flags); do_IRQ(TIMER_IRQ, regs); local_irq_restore(flags); @@ -31,26 +49,47 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) static int itimer_shutdown(struct clock_event_device *evt) { - os_timer_disable(); + if (time_travel_mode != TT_MODE_OFF) + time_travel_set_timer(TT_TMR_DISABLED, 0); + + if (time_travel_mode != TT_MODE_INFCPU) + os_timer_disable(); + return 0; } static int itimer_set_periodic(struct clock_event_device *evt) { - os_timer_set_interval(NULL, NULL); + unsigned long long interval = NSEC_PER_SEC / HZ; + + if (time_travel_mode != TT_MODE_OFF) + time_travel_set_timer(TT_TMR_PERIODIC, + time_travel_time + interval); + + if (time_travel_mode != TT_MODE_INFCPU) + os_timer_set_interval(interval); + return 0; } static int itimer_next_event(unsigned long delta, struct clock_event_device *evt) { - return os_timer_one_shot(delta); + delta += 1; + + if (time_travel_mode != TT_MODE_OFF) + time_travel_set_timer(TT_TMR_ONESHOT, + time_travel_time + delta); + + if (time_travel_mode != TT_MODE_INFCPU) + return os_timer_one_shot(delta); + + return 0; } static int itimer_one_shot(struct clock_event_device *evt) { - os_timer_one_shot(1); - return 0; + return itimer_next_event(0, evt); } static struct clock_event_device timer_clockevent = { @@ -87,6 +126,17 @@ static irqreturn_t um_timer(int irq, void *dev) static u64 timer_read(struct clocksource *cs) { + if (time_travel_mode != TT_MODE_OFF) { + /* + * We make reading the timer cost a bit so that we don't get + * stuck in loops that expect time to move more than the + * exact requested sleep amount, e.g. python's socket server, + * see https://bugs.python.org/issue37026. + */ + time_travel_set_time(time_travel_time + TIMER_MULTIPLIER); + return time_travel_time / TIMER_MULTIPLIER; + } + return os_nsecs() / TIMER_MULTIPLIER; } @@ -107,7 +157,7 @@ static void __init um_timer_setup(void) printk(KERN_ERR "register_timer : request_irq failed - " "errno = %d\n", -err); - err = os_timer_create(NULL); + err = os_timer_create(); if (err != 0) { printk(KERN_ERR "creation of timer failed - errno = %d\n", -err); return; @@ -123,7 +173,12 @@ static void __init um_timer_setup(void) void read_persistent_clock64(struct timespec64 *ts) { - long long nsecs = os_persistent_clock_emulation(); + long long nsecs; + + if (time_travel_start_set) + nsecs = time_travel_start + time_travel_time; + else + nsecs = os_persistent_clock_emulation(); set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC, nsecs % NSEC_PER_SEC); @@ -134,3 +189,65 @@ void __init time_init(void) timer_set_signal_handler(); late_time_init = um_timer_setup; } + +#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT +unsigned long calibrate_delay_is_known(void) +{ + if (time_travel_mode == TT_MODE_INFCPU) + return 1; + return 0; +} + +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_clocksource.name = "time-travel-clock"; + return 1; + } + + if (!*str) { + time_travel_mode = TT_MODE_BASIC; + timer_clockevent.name = "time-travel-timer"; + timer_clocksource.name = "time-travel-clock"; + return 1; + } + + return -EINVAL; +} + +__setup("time-travel", setup_time_travel); +__uml_help(setup_time_travel, +"time-travel\n" +"This option just enables basic time travel mode, in which the clock/timers\n" +"inside the UML instance skip forward when there's nothing to do, rather than\n" +"waiting for real time to elapse. However, instance CPU speed is limited by\n" +"the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n" +"clock (but quicker when there's nothing to do).\n" +"\n" +"time-travel=inf-cpu\n" +"This enables time travel mode with infinite processing power, in which there\n" +"are no wall clock timers, and any CPU processing happens - as seen from the\n" +"guest - instantly. This can be useful for accurate simulation regardless of\n" +"debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n" +"easily lead to getting stuck (e.g. if anything in the system busy loops).\n"); + +int setup_time_travel_start(char *str) +{ + int err; + + err = kstrtoull(str, 0, &time_travel_start); + if (err) + return err; + + time_travel_start_set = 1; + return 1; +} + +__setup("time-travel-start", setup_time_travel_start); +__uml_help(setup_time_travel_start, +"time-travel-start=<seconds>\n" +"Configure the UML instance's wall clock to start at this value rather than\n" +"the host's wall clock at the time of UML boot.\n"); +#endif |