1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk}) 4 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) 5 * Copyright (C) 2012-2014 Cisco Systems 6 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 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 /* 43 * In basic time-travel mode we still get real interrupts 44 * (signals) but since we don't read time from the OS, we 45 * must update the simulated time here to the expiry when 46 * we get a signal. 47 * This is not the case in inf-cpu mode, since there we 48 * never get any real signals from the OS. 49 */ 50 if (time_travel_mode == TT_MODE_BASIC) 51 time_travel_set_time(time_travel_timer_expiry); 52 53 local_irq_save(flags); 54 do_IRQ(TIMER_IRQ, regs); 55 local_irq_restore(flags); 56 } 57 58 static int itimer_shutdown(struct clock_event_device *evt) 59 { 60 if (time_travel_mode != TT_MODE_OFF) 61 time_travel_set_timer_mode(TT_TMR_DISABLED); 62 63 if (time_travel_mode != TT_MODE_INFCPU) 64 os_timer_disable(); 65 66 return 0; 67 } 68 69 static int itimer_set_periodic(struct clock_event_device *evt) 70 { 71 unsigned long long interval = NSEC_PER_SEC / HZ; 72 73 if (time_travel_mode != TT_MODE_OFF) { 74 time_travel_set_timer_mode(TT_TMR_PERIODIC); 75 time_travel_set_timer_expiry(time_travel_time + interval); 76 time_travel_set_timer_interval(interval); 77 } 78 79 if (time_travel_mode != TT_MODE_INFCPU) 80 os_timer_set_interval(interval); 81 82 return 0; 83 } 84 85 static int itimer_next_event(unsigned long delta, 86 struct clock_event_device *evt) 87 { 88 delta += 1; 89 90 if (time_travel_mode != TT_MODE_OFF) { 91 time_travel_set_timer_mode(TT_TMR_ONESHOT); 92 time_travel_set_timer_expiry(time_travel_time + delta); 93 } 94 95 if (time_travel_mode != TT_MODE_INFCPU) 96 return os_timer_one_shot(delta); 97 98 return 0; 99 } 100 101 static int itimer_one_shot(struct clock_event_device *evt) 102 { 103 return itimer_next_event(0, evt); 104 } 105 106 static struct clock_event_device timer_clockevent = { 107 .name = "posix-timer", 108 .rating = 250, 109 .cpumask = cpu_possible_mask, 110 .features = CLOCK_EVT_FEAT_PERIODIC | 111 CLOCK_EVT_FEAT_ONESHOT, 112 .set_state_shutdown = itimer_shutdown, 113 .set_state_periodic = itimer_set_periodic, 114 .set_state_oneshot = itimer_one_shot, 115 .set_next_event = itimer_next_event, 116 .shift = 0, 117 .max_delta_ns = 0xffffffff, 118 .max_delta_ticks = 0xffffffff, 119 .min_delta_ns = TIMER_MIN_DELTA, 120 .min_delta_ticks = TIMER_MIN_DELTA, // microsecond resolution should be enough for anyone, same as 640K RAM 121 .irq = 0, 122 .mult = 1, 123 }; 124 125 static irqreturn_t um_timer(int irq, void *dev) 126 { 127 if (get_current()->mm != NULL) 128 { 129 /* userspace - relay signal, results in correct userspace timers */ 130 os_alarm_process(get_current()->mm->context.id.u.pid); 131 } 132 133 (*timer_clockevent.event_handler)(&timer_clockevent); 134 135 return IRQ_HANDLED; 136 } 137 138 static u64 timer_read(struct clocksource *cs) 139 { 140 if (time_travel_mode != TT_MODE_OFF) { 141 /* 142 * We make reading the timer cost a bit so that we don't get 143 * stuck in loops that expect time to move more than the 144 * exact requested sleep amount, e.g. python's socket server, 145 * see https://bugs.python.org/issue37026. 146 */ 147 time_travel_set_time(time_travel_time + TIMER_MULTIPLIER); 148 return time_travel_time / TIMER_MULTIPLIER; 149 } 150 151 return os_nsecs() / TIMER_MULTIPLIER; 152 } 153 154 static struct clocksource timer_clocksource = { 155 .name = "timer", 156 .rating = 300, 157 .read = timer_read, 158 .mask = CLOCKSOURCE_MASK(64), 159 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 160 }; 161 162 static void __init um_timer_setup(void) 163 { 164 int err; 165 166 err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL); 167 if (err != 0) 168 printk(KERN_ERR "register_timer : request_irq failed - " 169 "errno = %d\n", -err); 170 171 err = os_timer_create(); 172 if (err != 0) { 173 printk(KERN_ERR "creation of timer failed - errno = %d\n", -err); 174 return; 175 } 176 177 err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER); 178 if (err) { 179 printk(KERN_ERR "clocksource_register_hz returned %d\n", err); 180 return; 181 } 182 clockevents_register_device(&timer_clockevent); 183 } 184 185 void read_persistent_clock64(struct timespec64 *ts) 186 { 187 long long nsecs; 188 189 if (time_travel_start_set) 190 nsecs = time_travel_start + time_travel_time; 191 else 192 nsecs = os_persistent_clock_emulation(); 193 194 set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC, 195 nsecs % NSEC_PER_SEC); 196 } 197 198 void __init time_init(void) 199 { 200 timer_set_signal_handler(); 201 late_time_init = um_timer_setup; 202 } 203 204 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT 205 unsigned long calibrate_delay_is_known(void) 206 { 207 if (time_travel_mode == TT_MODE_INFCPU) 208 return 1; 209 return 0; 210 } 211 212 int setup_time_travel(char *str) 213 { 214 if (strcmp(str, "=inf-cpu") == 0) { 215 time_travel_mode = TT_MODE_INFCPU; 216 timer_clockevent.name = "time-travel-timer-infcpu"; 217 timer_clocksource.name = "time-travel-clock"; 218 return 1; 219 } 220 221 if (!*str) { 222 time_travel_mode = TT_MODE_BASIC; 223 timer_clockevent.name = "time-travel-timer"; 224 timer_clocksource.name = "time-travel-clock"; 225 return 1; 226 } 227 228 return -EINVAL; 229 } 230 231 __setup("time-travel", setup_time_travel); 232 __uml_help(setup_time_travel, 233 "time-travel\n" 234 "This option just enables basic time travel mode, in which the clock/timers\n" 235 "inside the UML instance skip forward when there's nothing to do, rather than\n" 236 "waiting for real time to elapse. However, instance CPU speed is limited by\n" 237 "the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n" 238 "clock (but quicker when there's nothing to do).\n" 239 "\n" 240 "time-travel=inf-cpu\n" 241 "This enables time travel mode with infinite processing power, in which there\n" 242 "are no wall clock timers, and any CPU processing happens - as seen from the\n" 243 "guest - instantly. This can be useful for accurate simulation regardless of\n" 244 "debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n" 245 "easily lead to getting stuck (e.g. if anything in the system busy loops).\n"); 246 247 int setup_time_travel_start(char *str) 248 { 249 int err; 250 251 err = kstrtoull(str, 0, &time_travel_start); 252 if (err) 253 return err; 254 255 time_travel_start_set = 1; 256 return 1; 257 } 258 259 __setup("time-travel-start", setup_time_travel_start); 260 __uml_help(setup_time_travel_start, 261 "time-travel-start=<seconds>\n" 262 "Configure the UML instance's wall clock to start at this value rather than\n" 263 "the host's wall clock at the time of UML boot.\n"); 264 #endif 265