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
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
|
/*
* Copyright (C) 2004 PathScale, Inc
* Licensed under the GPL
*/
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <sys/mman.h>
#include "user_util.h"
#include "user.h"
#include "signal_kern.h"
#include "sysdep/sigcontext.h"
#include "sysdep/signal.h"
#include "sigcontext.h"
#include "mode.h"
#include "os.h"
/* These are the asynchronous signals. SIGVTALRM and SIGARLM are handled
* together under SIGVTALRM_BIT. SIGPROF is excluded because we want to
* be able to profile all of UML, not just the non-critical sections. If
* profiling is not thread-safe, then that is not my problem. We can disable
* profiling when SMP is enabled in that case.
*/
#define SIGIO_BIT 0
#define SIGIO_MASK (1 << SIGIO_BIT)
#define SIGVTALRM_BIT 1
#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
#define SIGALRM_BIT 2
#define SIGALRM_MASK (1 << SIGALRM_BIT)
static int signals_enabled = 1;
static int pending = 0;
void sig_handler(ARCH_SIGHDLR_PARAM)
{
struct sigcontext *sc;
int enabled;
/* Must be the first thing that this handler does - x86_64 stores
* the sigcontext in %rdx, and we need to save it before it has a
* chance to get trashed.
*/
ARCH_GET_SIGCONTEXT(sc, sig);
enabled = signals_enabled;
if(!enabled && (sig == SIGIO)){
pending |= SIGIO_MASK;
return;
}
block_signals();
CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
sig, sc);
set_signals(enabled);
}
extern int timer_irq_inited;
static void real_alarm_handler(int sig, struct sigcontext *sc)
{
if(!timer_irq_inited){
signals_enabled = 1;
return;
}
if(sig == SIGALRM)
switch_timers(0);
CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
sig, sc);
if(sig == SIGALRM)
switch_timers(1);
}
void alarm_handler(ARCH_SIGHDLR_PARAM)
{
struct sigcontext *sc;
int enabled;
ARCH_GET_SIGCONTEXT(sc, sig);
enabled = signals_enabled;
if(!signals_enabled){
if(sig == SIGVTALRM)
pending |= SIGVTALRM_MASK;
else pending |= SIGALRM_MASK;
return;
}
block_signals();
real_alarm_handler(sig, sc);
set_signals(enabled);
}
void set_sigstack(void *sig_stack, int size)
{
stack_t stack = ((stack_t) { .ss_flags = 0,
.ss_sp = (__ptr_t) sig_stack,
.ss_size = size - sizeof(void *) });
if(sigaltstack(&stack, NULL) != 0)
panic("enabling signal stack failed, errno = %d\n", errno);
}
void remove_sigstack(void)
{
stack_t stack = ((stack_t) { .ss_flags = SS_DISABLE,
.ss_sp = NULL,
.ss_size = 0 });
if(sigaltstack(&stack, NULL) != 0)
panic("disabling signal stack failed, errno = %d\n", errno);
}
void set_handler(int sig, void (*handler)(int), int flags, ...)
{
struct sigaction action;
va_list ap;
sigset_t sig_mask;
int mask;
va_start(ap, flags);
action.sa_handler = handler;
sigemptyset(&action.sa_mask);
while((mask = va_arg(ap, int)) != -1){
sigaddset(&action.sa_mask, mask);
}
va_end(ap);
action.sa_flags = flags;
action.sa_restorer = NULL;
if(sigaction(sig, &action, NULL) < 0)
panic("sigaction failed - errno = %d\n", errno);
sigemptyset(&sig_mask);
sigaddset(&sig_mask, sig);
if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
panic("sigprocmask failed - errno = %d\n", errno);
}
int change_sig(int signal, int on)
{
sigset_t sigset, old;
sigemptyset(&sigset);
sigaddset(&sigset, signal);
sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
return(!sigismember(&old, signal));
}
void block_signals(void)
{
signals_enabled = 0;
}
void unblock_signals(void)
{
int save_pending;
if(signals_enabled == 1)
return;
/* We loop because the IRQ handler returns with interrupts off. So,
* interrupts may have arrived and we need to re-enable them and
* recheck pending.
*/
while(1){
/* Save and reset save_pending after enabling signals. This
* way, pending won't be changed while we're reading it.
*/
signals_enabled = 1;
save_pending = pending;
if(save_pending == 0)
return;
pending = 0;
/* We have pending interrupts, so disable signals, as the
* handlers expect them off when they are called. They will
* be enabled again above.
*/
signals_enabled = 0;
/* Deal with SIGIO first because the alarm handler might
* schedule, leaving the pending SIGIO stranded until we come
* back here.
*/
if(save_pending & SIGIO_MASK)
CHOOSE_MODE_PROC(sig_handler_common_tt,
sig_handler_common_skas, SIGIO, NULL);
if(save_pending & SIGALRM_MASK)
real_alarm_handler(SIGALRM, NULL);
if(save_pending & SIGVTALRM_MASK)
real_alarm_handler(SIGVTALRM, NULL);
}
}
int get_signals(void)
{
return signals_enabled;
}
int set_signals(int enable)
{
int ret;
if(signals_enabled == enable)
return enable;
ret = signals_enabled;
if(enable)
unblock_signals();
else block_signals();
return ret;
}
void os_usr1_signal(int on)
{
change_sig(SIGUSR1, on);
}
|
