1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/*
* linux/kernel/itimer.c
*
* Copyright (C) 1992 Darren Senn
*/
/* These are all the functions necessary to implement itimers */
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
/*
* change timeval to jiffies, trying to avoid the
* most obvious overflows..
*
* The tv_*sec values are signed, but nothing seems to
* indicate whether we really should use them as signed values
* when doing itimers. POSIX doesn't mention this (but if
* alarm() uses itimers without checking, we have to use unsigned
* arithmetic).
*/
static unsigned long tvtojiffies(struct timeval *value)
{
unsigned long sec = (unsigned) value->tv_sec;
unsigned long usec = (unsigned) value->tv_usec;
if (sec > (ULONG_MAX / HZ))
return ULONG_MAX;
usec += 1000000 / HZ - 1;
usec /= 1000000 / HZ;
return HZ*sec+usec;
}
static void jiffiestotv(unsigned long jiffies, struct timeval *value)
{
value->tv_usec = (jiffies % HZ) * (1000000 / HZ);
value->tv_sec = jiffies / HZ;
}
static int _getitimer(int which, struct itimerval *value)
{
register unsigned long val, interval;
switch (which) {
case ITIMER_REAL:
interval = current->it_real_incr;
val = 0;
if (del_timer(¤t->real_timer)) {
unsigned long now = jiffies;
val = current->real_timer.expires;
add_timer(¤t->real_timer);
/* look out for negative/zero itimer.. */
if (val <= now)
val = now+1;
val -= now;
}
break;
case ITIMER_VIRTUAL:
val = current->it_virt_value;
interval = current->it_virt_incr;
break;
case ITIMER_PROF:
val = current->it_prof_value;
interval = current->it_prof_incr;
break;
default:
return(-EINVAL);
}
jiffiestotv(val, &value->it_value);
jiffiestotv(interval, &value->it_interval);
return 0;
}
/* SMP: Only we modify our itimer values. */
asmlinkage int sys_getitimer(int which, struct itimerval *value)
{
int error = -EFAULT;
struct itimerval get_buffer;
if (value) {
error = _getitimer(which, &get_buffer);
if (!error)
error = copy_to_user(value, &get_buffer, sizeof(get_buffer))
? -EFAULT : 0;
}
return error;
}
void it_real_fn(unsigned long __data)
{
struct task_struct * p = (struct task_struct *) __data;
unsigned long interval;
send_sig(SIGALRM, p, 1);
interval = p->it_real_incr;
if (interval) {
unsigned long timeout = jiffies + interval;
/* check for overflow */
if (timeout < interval)
timeout = ULONG_MAX;
p->real_timer.expires = timeout;
add_timer(&p->real_timer);
}
}
int _setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
register unsigned long i, j;
int k;
i = tvtojiffies(&value->it_interval);
j = tvtojiffies(&value->it_value);
if (ovalue && (k = _getitimer(which, ovalue)) < 0)
return k;
switch (which) {
case ITIMER_REAL:
del_timer(¤t->real_timer);
current->it_real_value = j;
current->it_real_incr = i;
if (!j)
break;
i = j + jiffies;
/* check for overflow.. */
if (i < j)
i = ULONG_MAX;
current->real_timer.expires = i;
add_timer(¤t->real_timer);
break;
case ITIMER_VIRTUAL:
if (j)
j++;
current->it_virt_value = j;
current->it_virt_incr = i;
break;
case ITIMER_PROF:
if (j)
j++;
current->it_prof_value = j;
current->it_prof_incr = i;
break;
default:
return -EINVAL;
}
return 0;
}
/* SMP: Again, only we play with our itimers, and signals are SMP safe
* now so that is not an issue at all anymore.
*/
asmlinkage int sys_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct itimerval set_buffer, get_buffer;
int error;
if (value) {
if(verify_area(VERIFY_READ, value, sizeof(*value)))
return -EFAULT;
if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
return -EFAULT;
} else
memset((char *) &set_buffer, 0, sizeof(set_buffer));
error = _setitimer(which, &set_buffer, ovalue ? &get_buffer : 0);
if (error || !ovalue)
return error;
if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
return -EFAULT;
return 0;
}
|
