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(TT_TMR_DISABLED, 0);
  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(TT_TMR_PERIODIC,
  67                                       time_travel_time + interval);
  68
  69         if (time_travel_mode != TT_MODE_INFCPU)
  70                 os_timer_set_interval(interval);
  71
  72         return 0;
  73 }
  74
  75 static int itimer_next_event(unsigned long delta,
  76                              struct clock_event_device *evt)
  77 {
  78         delta += 1;
  79
  80         if (time_travel_mode != TT_MODE_OFF)
  81                 time_travel_set_timer(TT_TMR_ONESHOT,
  82                                       time_travel_time + delta);
  83
  84         if (time_travel_mode != TT_MODE_INFCPU)
  85                 return os_timer_one_shot(delta);
  86
  87         return 0;
  88 }
  89
  90 static int itimer_one_shot(struct clock_event_device *evt)
  91 {
  92         return itimer_next_event(0, evt);
  93 }
  94
  95 static struct clock_event_device timer_clockevent = {
  96         .name                   = "posix-timer",
  97         .rating                 = 250,
  98         .cpumask                = cpu_possible_mask,
  99         .features               = CLOCK_EVT_FEAT_PERIODIC |
 100                                   CLOCK_EVT_FEAT_ONESHOT,
 101         .set_state_shutdown     = itimer_shutdown,
 102         .set_state_periodic     = itimer_set_periodic,
 103         .set_state_oneshot      = itimer_one_shot,
 104         .set_next_event         = itimer_next_event,
 105         .shift                  = 0,
 106         .max_delta_ns           = 0xffffffff,
 107         .max_delta_ticks        = 0xffffffff,
 108         .min_delta_ns           = TIMER_MIN_DELTA,
 109         .min_delta_ticks        = TIMER_MIN_DELTA, // microsecond resolution should be enough for anyone, same as 640K RAM
 110         .irq                    = 0,
 111         .mult                   = 1,
 112 };
 113
 114 static irqreturn_t um_timer(int irq, void *dev)
 115 {
 116         if (get_current()->mm != NULL)
 117         {
 118         /* userspace - relay signal, results in correct userspace timers */
 119                 os_alarm_process(get_current()->mm->context.id.u.pid);
 120         }
 121
 122         (*timer_clockevent.event_handler)(&timer_clockevent);
 123
 124         return IRQ_HANDLED;
 125 }
 126
 127 static u64 timer_read(struct clocksource *cs)
 128 {
 129         if (time_travel_mode != TT_MODE_OFF) {
 130                 /*
 131                  * We make reading the timer cost a bit so that we don't get
 132                  * stuck in loops that expect time to move more than the
 133                  * exact requested sleep amount, e.g. python's socket server,
 134                  * see https://bugs.python.org/issue37026.
 135                  */
 136                 time_travel_set_time(time_travel_time + TIMER_MULTIPLIER);
 137                 return time_travel_time / TIMER_MULTIPLIER;
 138         }
 139
 140         return os_nsecs() / TIMER_MULTIPLIER;
 141 }
 142
 143 static struct clocksource timer_clocksource = {
 144         .name           = "timer",
 145         .rating         = 300,
 146         .read           = timer_read,
 147         .mask           = CLOCKSOURCE_MASK(64),
 148         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 149 };
 150
 151 static void __init um_timer_setup(void)
 152 {
 153         int err;
 154
 155         err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
 156         if (err != 0)
 157                 printk(KERN_ERR "register_timer : request_irq failed - "
 158                        "errno = %d\n", -err);
 159
 160         err = os_timer_create();
 161         if (err != 0) {
 162                 printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
 163                 return;
 164         }
 165
 166         err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
 167         if (err) {
 168                 printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
 169                 return;
 170         }
 171         clockevents_register_device(&timer_clockevent);
 172 }
 173
 174 void read_persistent_clock64(struct timespec64 *ts)
 175 {
 176         long long nsecs;
 177
 178         if (time_travel_start_set)
 179                 nsecs = time_travel_start + time_travel_time;
 180         else
 181                 nsecs = os_persistent_clock_emulation();
 182
 183         set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC,
 184                                   nsecs % NSEC_PER_SEC);
 185 }
 186
 187 void __init time_init(void)
 188 {
 189         timer_set_signal_handler();
 190         late_time_init = um_timer_setup;
 191 }
 192
 193 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 194 unsigned long calibrate_delay_is_known(void)
 195 {
 196         if (time_travel_mode == TT_MODE_INFCPU)
 197                 return 1;
 198         return 0;
 199 }
 200
 201 int setup_time_travel(char *str)
 202 {
 203         if (strcmp(str, "=inf-cpu") == 0) {
 204                 time_travel_mode = TT_MODE_INFCPU;
 205                 timer_clockevent.name = "time-travel-timer-infcpu";
 206                 timer_clocksource.name = "time-travel-clock";
 207                 return 1;
 208         }
 209
 210         if (!*str) {
 211                 time_travel_mode = TT_MODE_BASIC;
 212                 timer_clockevent.name = "time-travel-timer";
 213                 timer_clocksource.name = "time-travel-clock";
 214                 return 1;
 215         }
 216
 217         return -EINVAL;
 218 }
 219
 220 __setup("time-travel", setup_time_travel);
 221 __uml_help(setup_time_travel,
 222 "time-travel\n"
 223 "This option just enables basic time travel mode, in which the clock/timers\n"
 224 "inside the UML instance skip forward when there's nothing to do, rather than\n"
 225 "waiting for real time to elapse. However, instance CPU speed is limited by\n"
 226 "the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n"
 227 "clock (but quicker when there's nothing to do).\n"
 228 "\n"
 229 "time-travel=inf-cpu\n"
 230 "This enables time travel mode with infinite processing power, in which there\n"
 231 "are no wall clock timers, and any CPU processing happens - as seen from the\n"
 232 "guest - instantly. This can be useful for accurate simulation regardless of\n"
 233 "debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n"
 234 "easily lead to getting stuck (e.g. if anything in the system busy loops).\n");
 235
 236 int setup_time_travel_start(char *str)
 237 {
 238         int err;
 239
 240         err = kstrtoull(str, 0, &time_travel_start);
 241         if (err)
 242                 return err;
 243
 244         time_travel_start_set = 1;
 245         return 1;
 246 }
 247
 248 __setup("time-travel-start", setup_time_travel_start);
 249 __uml_help(setup_time_travel_start,
 250 "time-travel-start=<seconds>\n"
 251 "Configure the UML instance's wall clock to start at this value rather than\n"
 252 "the host's wall clock at the time of UML boot.\n");
 253 #endif