ia64/xen-unstable

view extras/mini-os/time.c @ 7238:971e7c7411b3

Raise an exception if an error appears on the pipes to our children, and make
sure that the child's pipes are closed even under that exception. Move the
handling of POLLHUP to the end of the loop, so that we guarantee to read any
remaining data from the child if POLLHUP and POLLIN appear at the same time.

Signed-off-by: Ewan Mellor <ewan@xensource.com>
author emellor@ewan
date Thu Oct 06 10:13:11 2005 +0100 (2005-10-06)
parents 06d84bf87159
children f8087c9297aa
line source
1 /* -*- Mode:C; c-basic-offset:4; tab-width:4 -*-
2 ****************************************************************************
3 * (C) 2003 - Rolf Neugebauer - Intel Research Cambridge
4 * (C) 2002-2003 - Keir Fraser - University of Cambridge
5 * (C) 2005 - Grzegorz Milos - Intel Research Cambridge
6 ****************************************************************************
7 *
8 * File: time.c
9 * Author: Rolf Neugebauer and Keir Fraser
10 * Changes: Grzegorz Milos
11 *
12 * Description: Simple time and timer functions
13 *
14 * Permission is hereby granted, free of charge, to any person obtaining a copy
15 * of this software and associated documentation files (the "Software"), to
16 * deal in the Software without restriction, including without limitation the
17 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
18 * sell copies of the Software, and to permit persons to whom the Software is
19 * furnished to do so, subject to the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
30 * DEALINGS IN THE SOFTWARE.
31 */
34 #include <os.h>
35 #include <traps.h>
36 #include <types.h>
37 #include <hypervisor.h>
38 #include <events.h>
39 #include <time.h>
40 #include <lib.h>
42 /************************************************************************
43 * Time functions
44 *************************************************************************/
46 /* These are peridically updated in shared_info, and then copied here. */
47 struct shadow_time_info {
48 u64 tsc_timestamp; /* TSC at last update of time vals. */
49 u64 system_timestamp; /* Time, in nanosecs, since boot. */
50 u32 tsc_to_nsec_mul;
51 u32 tsc_to_usec_mul;
52 int tsc_shift;
53 u32 version;
54 };
55 static struct timespec shadow_ts;
56 static u32 shadow_ts_version;
58 static struct shadow_time_info shadow;
61 #ifndef rmb
62 #define rmb() __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
63 #endif
65 #define HANDLE_USEC_OVERFLOW(_tv) \
66 do { \
67 while ( (_tv)->tv_usec >= 1000000 ) \
68 { \
69 (_tv)->tv_usec -= 1000000; \
70 (_tv)->tv_sec++; \
71 } \
72 } while ( 0 )
74 static inline int time_values_up_to_date(void)
75 {
76 struct vcpu_time_info *src = &HYPERVISOR_shared_info->vcpu_time[0];
78 return (shadow.version == src->version);
79 }
82 /*
83 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
84 * yielding a 64-bit result.
85 */
86 static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
87 {
88 u64 product;
89 #ifdef __i386__
90 u32 tmp1, tmp2;
91 #endif
93 if ( shift < 0 )
94 delta >>= -shift;
95 else
96 delta <<= shift;
98 #ifdef __i386__
99 __asm__ (
100 "mul %5 ; "
101 "mov %4,%%eax ; "
102 "mov %%edx,%4 ; "
103 "mul %5 ; "
104 "add %4,%%eax ; "
105 "xor %5,%5 ; "
106 "adc %5,%%edx ; "
107 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
108 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
109 #else
110 __asm__ (
111 "mul %%rdx ; shrd $32,%%rdx,%%rax"
112 : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
113 #endif
115 return product;
116 }
119 static unsigned long get_nsec_offset(void)
120 {
121 u64 now, delta;
122 rdtscll(now);
123 delta = now - shadow.tsc_timestamp;
124 return scale_delta(delta, shadow.tsc_to_nsec_mul, shadow.tsc_shift);
125 }
128 static void get_time_values_from_xen(void)
129 {
130 struct vcpu_time_info *src = &HYPERVISOR_shared_info->vcpu_time[0];
132 do {
133 shadow.version = src->version;
134 rmb();
135 shadow.tsc_timestamp = src->tsc_timestamp;
136 shadow.system_timestamp = src->system_time;
137 shadow.tsc_to_nsec_mul = src->tsc_to_system_mul;
138 shadow.tsc_shift = src->tsc_shift;
139 rmb();
140 }
141 while ((src->version & 1) | (shadow.version ^ src->version));
143 shadow.tsc_to_usec_mul = shadow.tsc_to_nsec_mul / 1000;
144 }
149 /* monotonic_clock(): returns # of nanoseconds passed since time_init()
150 * Note: This function is required to return accurate
151 * time even in the absence of multiple timer ticks.
152 */
153 u64 monotonic_clock(void)
154 {
155 u64 time;
156 u32 local_time_version;
158 do {
159 local_time_version = shadow.version;
160 rmb();
161 time = shadow.system_timestamp + get_nsec_offset();
162 if (!time_values_up_to_date())
163 get_time_values_from_xen();
164 rmb();
165 } while (local_time_version != shadow.version);
167 return time;
168 }
170 static void update_wallclock(void)
171 {
172 shared_info_t *s = HYPERVISOR_shared_info;
174 do {
175 shadow_ts_version = s->wc_version;
176 rmb();
177 shadow_ts.ts_sec = s->wc_sec;
178 shadow_ts.ts_nsec = s->wc_nsec;
179 rmb();
180 }
181 while ((s->wc_version & 1) | (shadow_ts_version ^ s->wc_version));
182 }
185 void gettimeofday(struct timeval *tv)
186 {
187 u64 nsec = monotonic_clock();
188 nsec += shadow_ts.ts_nsec;
191 tv->tv_sec = shadow_ts.ts_sec;
192 tv->tv_sec += NSEC_TO_SEC(nsec);
193 tv->tv_usec = NSEC_TO_USEC(nsec % 1000000000UL);
194 }
197 static void print_current_time(void)
198 {
199 struct timeval tv;
201 gettimeofday(&tv);
202 printk("T(s=%ld us=%ld)\n", tv.tv_sec, tv.tv_usec);
203 }
206 void block_domain(u32 millisecs)
207 {
208 struct timeval tv;
209 gettimeofday(&tv);
210 HYPERVISOR_set_timer_op(monotonic_clock() + 1000000LL * (s64) millisecs);
211 HYPERVISOR_block();
212 }
215 /*
216 * Just a dummy
217 */
218 static void timer_handler(int ev, struct pt_regs *regs)
219 {
220 static int i;
222 get_time_values_from_xen();
223 update_wallclock();
224 i++;
225 if (i >= 1000) {
226 print_current_time();
227 i = 0;
228 }
229 }
233 void init_time(void)
234 {
235 printk("Initialising timer interface\n");
236 bind_virq(VIRQ_TIMER, &timer_handler);
237 }