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7#include <stdlib.h>
8#include <stdarg.h>
9#include <errno.h>
10#include <signal.h>
11#include <strings.h>
12#include "as-layout.h"
13#include "kern_util.h"
14#include "os.h"
15#include "process.h"
16#include "sysdep/barrier.h"
17#include "sysdep/sigcontext.h"
18#include "user.h"
19
20
21#define barrier() __asm__ __volatile__("": : :"memory")
22
23void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
24 [SIGTRAP] = relay_signal,
25 [SIGFPE] = relay_signal,
26 [SIGILL] = relay_signal,
27 [SIGWINCH] = winch,
28 [SIGBUS] = bus_handler,
29 [SIGSEGV] = segv_handler,
30 [SIGIO] = sigio_handler,
31 [SIGVTALRM] = timer_handler };
32
33static void sig_handler_common(int sig, struct sigcontext *sc)
34{
35 struct uml_pt_regs r;
36 int save_errno = errno;
37
38 r.is_user = 0;
39 if (sig == SIGSEGV) {
40
41 copy_sc(&r, sc);
42 GET_FAULTINFO_FROM_SC(r.faultinfo, sc);
43 }
44
45
46 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
47 unblock_signals();
48
49 (*sig_info[sig])(sig, &r);
50
51 errno = save_errno;
52}
53
54
55
56
57
58
59
60#define SIGIO_BIT 0
61#define SIGIO_MASK (1 << SIGIO_BIT)
62
63#define SIGVTALRM_BIT 1
64#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
65
66static int signals_enabled;
67static unsigned int signals_pending;
68
69void sig_handler(int sig, struct sigcontext *sc)
70{
71 int enabled;
72
73 enabled = signals_enabled;
74 if (!enabled && (sig == SIGIO)) {
75 signals_pending |= SIGIO_MASK;
76 return;
77 }
78
79 block_signals();
80
81 sig_handler_common(sig, sc);
82
83 set_signals(enabled);
84}
85
86static void real_alarm_handler(struct sigcontext *sc)
87{
88 struct uml_pt_regs regs;
89
90 if (sc != NULL)
91 copy_sc(®s, sc);
92 regs.is_user = 0;
93 unblock_signals();
94 timer_handler(SIGVTALRM, ®s);
95}
96
97void alarm_handler(int sig, struct sigcontext *sc)
98{
99 int enabled;
100
101 enabled = signals_enabled;
102 if (!signals_enabled) {
103 signals_pending |= SIGVTALRM_MASK;
104 return;
105 }
106
107 block_signals();
108
109 real_alarm_handler(sc);
110 set_signals(enabled);
111}
112
113void timer_init(void)
114{
115 set_handler(SIGVTALRM, (__sighandler_t) alarm_handler,
116 SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGWINCH, -1);
117}
118
119void set_sigstack(void *sig_stack, int size)
120{
121 stack_t stack = ((stack_t) { .ss_flags = 0,
122 .ss_sp = (__ptr_t) sig_stack,
123 .ss_size = size - sizeof(void *) });
124
125 if (sigaltstack(&stack, NULL) != 0)
126 panic("enabling signal stack failed, errno = %d\n", errno);
127}
128
129static void (*handlers[_NSIG])(int sig, struct sigcontext *sc);
130
131void handle_signal(int sig, struct sigcontext *sc)
132{
133 unsigned long pending = 1UL << sig;
134
135 do {
136 int nested, bail;
137
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145
146
147
148 bail = to_irq_stack(&pending);
149 if (bail)
150 return;
151
152 nested = pending & 1;
153 pending &= ~1;
154
155 while ((sig = ffs(pending)) != 0){
156 sig--;
157 pending &= ~(1 << sig);
158 (*handlers[sig])(sig, sc);
159 }
160
161
162
163
164
165
166
167 if (!nested)
168 pending = from_irq_stack(nested);
169 } while (pending);
170}
171
172extern void hard_handler(int sig);
173
174void set_handler(int sig, void (*handler)(int), int flags, ...)
175{
176 struct sigaction action;
177 va_list ap;
178 sigset_t sig_mask;
179 int mask;
180
181 handlers[sig] = (void (*)(int, struct sigcontext *)) handler;
182 action.sa_handler = hard_handler;
183
184 sigemptyset(&action.sa_mask);
185
186 va_start(ap, flags);
187 while ((mask = va_arg(ap, int)) != -1)
188 sigaddset(&action.sa_mask, mask);
189 va_end(ap);
190
191 if (sig == SIGSEGV)
192 flags |= SA_NODEFER;
193
194 action.sa_flags = flags;
195 action.sa_restorer = NULL;
196 if (sigaction(sig, &action, NULL) < 0)
197 panic("sigaction failed - errno = %d\n", errno);
198
199 sigemptyset(&sig_mask);
200 sigaddset(&sig_mask, sig);
201 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
202 panic("sigprocmask failed - errno = %d\n", errno);
203}
204
205int change_sig(int signal, int on)
206{
207 sigset_t sigset;
208
209 sigemptyset(&sigset);
210 sigaddset(&sigset, signal);
211 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
212 return -errno;
213
214 return 0;
215}
216
217void block_signals(void)
218{
219 signals_enabled = 0;
220
221
222
223
224
225
226 barrier();
227}
228
229void unblock_signals(void)
230{
231 int save_pending;
232
233 if (signals_enabled == 1)
234 return;
235
236
237
238
239
240
241 while (1) {
242
243
244
245
246 signals_enabled = 1;
247
248
249
250
251
252 barrier();
253
254 save_pending = signals_pending;
255 if (save_pending == 0)
256 return;
257
258 signals_pending = 0;
259
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264
265
266 signals_enabled = 0;
267
268
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270
271
272
273 if (save_pending & SIGIO_MASK)
274 sig_handler_common(SIGIO, NULL);
275
276 if (save_pending & SIGVTALRM_MASK)
277 real_alarm_handler(NULL);
278 }
279}
280
281int get_signals(void)
282{
283 return signals_enabled;
284}
285
286int set_signals(int enable)
287{
288 int ret;
289 if (signals_enabled == enable)
290 return enable;
291
292 ret = signals_enabled;
293 if (enable)
294 unblock_signals();
295 else block_signals();
296
297 return ret;
298}
299