arch/um/kernel/time.c

   1 /*
   2  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
   3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   4  * Copyright (C) 2012-2014 Cisco Systems
   5  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   6  * Licensed under the GPL
   7  */
   8
   9 #include <linux/clockchips.h>
  10 #include <linux/init.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/mm.h>
  14 #include <linux/sched.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/threads.h>
  17 #include <asm/irq.h>
  18 #include <asm/param.h>
  19 #include <kern_util.h>
  20 #include <os.h>
  21 #include <timer-internal.h>
  22 #include <shared/init.h>
  23
  24 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
  25 enum time_travel_mode time_travel_mode;
  26 unsigned long long time_travel_time;
  27 enum time_travel_timer_mode time_travel_timer_mode;
  28 unsigned long long time_travel_timer_expiry;
  29 unsigned long long time_travel_timer_interval;
  30
  31 static bool time_travel_start_set;
  32 static unsigned long long time_travel_start;
  33 #else
  34 #define time_travel_start_set 0
  35 #define time_travel_start 0
  36 #endif
  37
  38 void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
  39 {
  40         unsigned long flags;
  41
  42         if (time_travel_mode != TT_MODE_OFF)
  43                 time_travel_set_time(time_travel_timer_expiry);
  44
  45         local_irq_save(flags);
  46         do_IRQ(TIMER_IRQ, regs);
  47         local_irq_restore(flags);
  48 }
  49
  50 static int itimer_shutdown(struct clock_event_device *evt)
  51 {
  52         if (time_travel_mode != TT_MODE_OFF)
  53                 time_travel_set_timer_mode(TT_TMR_DISABLED);
  54
  55         if (time_travel_mode != TT_MODE_INFCPU)
  56                 os_timer_disable();
  57
  58         return 0;
  59 }
  60
  61 static int itimer_set_periodic(struct clock_event_device *evt)
  62 {
  63         unsigned long long interval = NSEC_PER_SEC / HZ;
  64
  65         if (time_travel_mode != TT_MODE_OFF) {
  66                 time_travel_set_timer_mode(TT_TMR_PERIODIC);
  67                 time_travel_set_timer_expiry(time_travel_time + interval);
  68         }
  69
  70         if (time_travel_mode != TT_MODE_INFCPU)
  71                 os_timer_set_interval(interval);
  72
  73         return 0;
  74 }
  75
  76 static int itimer_next_event(unsigned long delta,
  77                              struct clock_event_device *evt)
  78 {
  79         delta += 1;
  80
  81         if (time_travel_mode != TT_MODE_OFF) {
  82                 time_travel_set_timer_mode(TT_TMR_ONESHOT);
  83                 time_travel_set_timer_expiry(time_travel_time + delta);
  84         }
  85
  86         if (time_travel_mode != TT_MODE_INFCPU)
  87                 return os_timer_one_shot(delta);
  88
  89         return 0;
  90 }
  91
  92 static int itimer_one_shot(struct clock_event_device *evt)
  93 {
  94         return itimer_next_event(0, evt);
  95 }
  96
  97 static struct clock_event_device timer_clockevent = {
  98         .name                   = "posix-timer",
  99         .rating                 = 250,
 100         .cpumask                = cpu_possible_mask,
 101         .features               = CLOCK_EVT_FEAT_PERIODIC |
 102                                   CLOCK_EVT_FEAT_ONESHOT,
 103         .set_state_shutdown     = itimer_shutdown,
 104         .set_state_periodic     = itimer_set_periodic,
 105         .set_state_oneshot      = itimer_one_shot,
 106         .set_next_event         = itimer_next_event,
 107         .shift                  = 0,
 108         .max_delta_ns           = 0xffffffff,
 109         .max_delta_ticks        = 0xffffffff,
 110         .min_delta_ns           = TIMER_MIN_DELTA,
 111         .min_delta_ticks        = TIMER_MIN_DELTA, // microsecond resolution should be enough for anyone, same as 640K RAM
 112         .irq                    = 0,
 113         .mult                   = 1,
 114 };
 115
 116 static irqreturn_t um_timer(int irq, void *dev)
 117 {
 118         if (get_current()->mm != NULL)
 119         {
 120         /* userspace - relay signal, results in correct userspace timers */
 121                 os_alarm_process(get_current()->mm->context.id.u.pid);
 122         }
 123
 124         (*timer_clockevent.event_handler)(&timer_clockevent);
 125
 126         return IRQ_HANDLED;
 127 }
 128
 129 static u64 timer_read(struct clocksource *cs)
 130 {
 131         if (time_travel_mode != TT_MODE_OFF) {
 132                 /*
 133                  * We make reading the timer cost a bit so that we don't get
 134                  * stuck in loops that expect time to move more than the
 135                  * exact requested sleep amount, e.g. python's socket server,
 136                  * see https://bugs.python.org/issue37026.
 137                  */
 138                 time_travel_set_time(time_travel_time + TIMER_MULTIPLIER);
 139                 return time_travel_time / TIMER_MULTIPLIER;
 140         }
 141
 142         return os_nsecs() / TIMER_MULTIPLIER;
 143 }
 144
 145 static struct clocksource timer_clocksource = {
 146         .name           = "timer",
 147         .rating         = 300,
 148         .read           = timer_read,
 149         .mask           = CLOCKSOURCE_MASK(64),
 150         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 151 };
 152
 153 static void __init um_timer_setup(void)
 154 {
 155         int err;
 156
 157         err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
 158         if (err != 0)
 159                 printk(KERN_ERR "register_timer : request_irq failed - "
 160                        "errno = %d\n", -err);
 161
 162         err = os_timer_create();
 163         if (err != 0) {
 164                 printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
 165                 return;
 166         }
 167
 168         err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
 169         if (err) {
 170                 printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
 171                 return;
 172         }
 173         clockevents_register_device(&timer_clockevent);
 174 }
 175
 176 void read_persistent_clock64(struct timespec64 *ts)
 177 {
 178         long long nsecs;
 179
 180         if (time_travel_start_set)
 181                 nsecs = time_travel_start + time_travel_time;
 182         else
 183                 nsecs = os_persistent_clock_emulation();
 184
 185         set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC,
 186                                   nsecs % NSEC_PER_SEC);
 187 }
 188
 189 void __init time_init(void)
 190 {
 191         timer_set_signal_handler();
 192         late_time_init = um_timer_setup;
 193 }
 194
 195 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 196 unsigned long calibrate_delay_is_known(void)
 197 {
 198         if (time_travel_mode == TT_MODE_INFCPU)
 199                 return 1;
 200         return 0;
 201 }
 202
 203 int setup_time_travel(char *str)
 204 {
 205         if (strcmp(str, "=inf-cpu") == 0) {
 206                 time_travel_mode = TT_MODE_INFCPU;
 207                 timer_clockevent.name = "time-travel-timer-infcpu";
 208                 timer_clocksource.name = "time-travel-clock";
 209                 return 1;
 210         }
 211
 212         if (!*str) {
 213                 time_travel_mode = TT_MODE_BASIC;
 214                 timer_clockevent.name = "time-travel-timer";
 215                 timer_clocksource.name = "time-travel-clock";
 216                 return 1;
 217         }
 218
 219         return -EINVAL;
 220 }
 221
 222 __setup("time-travel", setup_time_travel);
 223 __uml_help(setup_time_travel,
 224 "time-travel\n"
 225 "This option just enables basic time travel mode, in which the clock/timers\n"
 226 "inside the UML instance skip forward when there's nothing to do, rather than\n"
 227 "waiting for real time to elapse. However, instance CPU speed is limited by\n"
 228 "the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n"
 229 "clock (but quicker when there's nothing to do).\n"
 230 "\n"
 231 "time-travel=inf-cpu\n"
 232 "This enables time travel mode with infinite processing power, in which there\n"
 233 "are no wall clock timers, and any CPU processing happens - as seen from the\n"
 234 "guest - instantly. This can be useful for accurate simulation regardless of\n"
 235 "debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n"
 236 "easily lead to getting stuck (e.g. if anything in the system busy loops).\n");
 237
 238 int setup_time_travel_start(char *str)
 239 {
 240         int err;
 241
 242         err = kstrtoull(str, 0, &time_travel_start);
 243         if (err)
 244                 return err;
 245
 246         time_travel_start_set = 1;
 247         return 1;
 248 }
 249
 250 __setup("time-travel-start", setup_time_travel_start);
 251 __uml_help(setup_time_travel_start,
 252 "time-travel-start=<seconds>\n"
 253 "Configure the UML instance's wall clock to start at this value rather than\n"
 254 "the host's wall clock at the time of UML boot.\n");
 255 #endif