1 /*
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6 #include <stddef.h>
7 #include <errno.h>
8 #include <signal.h>
9 #include <time.h>
10 #include <sys/time.h>
11 #include <kern_util.h>
12 #include <os.h>
13 #include "internal.h"
14
set_interval(void)15 int set_interval(void)
16 {
17 int usec = UM_USEC_PER_SEC / UM_HZ;
18 struct itimerval interval = ((struct itimerval) { { 0, usec },
19 { 0, usec } });
20
21 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
22 return -errno;
23
24 return 0;
25 }
26
timer_one_shot(int ticks)27 int timer_one_shot(int ticks)
28 {
29 unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
30 unsigned long sec = usec / UM_USEC_PER_SEC;
31 struct itimerval interval;
32
33 usec %= UM_USEC_PER_SEC;
34 interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
35
36 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
37 return -errno;
38
39 return 0;
40 }
41
42 /**
43 * timeval_to_ns - Convert timeval to nanoseconds
44 * @ts: pointer to the timeval variable to be converted
45 *
46 * Returns the scalar nanosecond representation of the timeval
47 * parameter.
48 *
49 * Ripped from linux/time.h because it's a kernel header, and thus
50 * unusable from here.
51 */
timeval_to_ns(const struct timeval * tv)52 static inline long long timeval_to_ns(const struct timeval *tv)
53 {
54 return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
55 tv->tv_usec * UM_NSEC_PER_USEC;
56 }
57
disable_timer(void)58 long long disable_timer(void)
59 {
60 struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
61 long long remain, max = UM_NSEC_PER_SEC / UM_HZ;
62
63 if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
64 printk(UM_KERN_ERR "disable_timer - setitimer failed, "
65 "errno = %d\n", errno);
66
67 remain = timeval_to_ns(&time.it_value);
68 if (remain > max)
69 remain = max;
70
71 return remain;
72 }
73
os_nsecs(void)74 long long os_nsecs(void)
75 {
76 struct timeval tv;
77
78 gettimeofday(&tv, NULL);
79 return timeval_to_ns(&tv);
80 }
81
82 #ifdef UML_CONFIG_NO_HZ_COMMON
after_sleep_interval(struct timespec * ts)83 static int after_sleep_interval(struct timespec *ts)
84 {
85 return 0;
86 }
87
deliver_alarm(void)88 static void deliver_alarm(void)
89 {
90 alarm_handler(SIGVTALRM, NULL, NULL);
91 }
92
sleep_time(unsigned long long nsecs)93 static unsigned long long sleep_time(unsigned long long nsecs)
94 {
95 return nsecs;
96 }
97
98 #else
99 unsigned long long last_tick;
100 unsigned long long skew;
101
deliver_alarm(void)102 static void deliver_alarm(void)
103 {
104 unsigned long long this_tick = os_nsecs();
105 int one_tick = UM_NSEC_PER_SEC / UM_HZ;
106
107 /* Protection against the host's time going backwards */
108 if ((last_tick != 0) && (this_tick < last_tick))
109 this_tick = last_tick;
110
111 if (last_tick == 0)
112 last_tick = this_tick - one_tick;
113
114 skew += this_tick - last_tick;
115
116 while (skew >= one_tick) {
117 alarm_handler(SIGVTALRM, NULL, NULL);
118 skew -= one_tick;
119 }
120
121 last_tick = this_tick;
122 }
123
sleep_time(unsigned long long nsecs)124 static unsigned long long sleep_time(unsigned long long nsecs)
125 {
126 return nsecs > skew ? nsecs - skew : 0;
127 }
128
timespec_to_us(const struct timespec * ts)129 static inline long long timespec_to_us(const struct timespec *ts)
130 {
131 return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
132 ts->tv_nsec / UM_NSEC_PER_USEC;
133 }
134
after_sleep_interval(struct timespec * ts)135 static int after_sleep_interval(struct timespec *ts)
136 {
137 int usec = UM_USEC_PER_SEC / UM_HZ;
138 long long start_usecs = timespec_to_us(ts);
139 struct timeval tv;
140 struct itimerval interval;
141
142 /*
143 * It seems that rounding can increase the value returned from
144 * setitimer to larger than the one passed in. Over time,
145 * this will cause the remaining time to be greater than the
146 * tick interval. If this happens, then just reduce the first
147 * tick to the interval value.
148 */
149 if (start_usecs > usec)
150 start_usecs = usec;
151
152 start_usecs -= skew / UM_NSEC_PER_USEC;
153 if (start_usecs < 0)
154 start_usecs = 0;
155
156 tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC,
157 .tv_usec = start_usecs % UM_USEC_PER_SEC });
158 interval = ((struct itimerval) { { 0, usec }, tv });
159
160 if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
161 return -errno;
162
163 return 0;
164 }
165 #endif
166
idle_sleep(unsigned long long nsecs)167 void idle_sleep(unsigned long long nsecs)
168 {
169 struct timespec ts;
170
171 /*
172 * nsecs can come in as zero, in which case, this starts a
173 * busy loop. To prevent this, reset nsecs to the tick
174 * interval if it is zero.
175 */
176 if (nsecs == 0)
177 nsecs = UM_NSEC_PER_SEC / UM_HZ;
178
179 nsecs = sleep_time(nsecs);
180 ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC,
181 .tv_nsec = nsecs % UM_NSEC_PER_SEC });
182
183 if (nanosleep(&ts, &ts) == 0)
184 deliver_alarm();
185 after_sleep_interval(&ts);
186 }
187