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9#include <stdlib.h>
10#include <stdarg.h>
11#include <errno.h>
12#include <signal.h>
13#include <strings.h>
14#include <as-layout.h>
15#include <kern_util.h>
16#include <os.h>
17#include <sysdep/mcontext.h>
18#include <um_malloc.h>
19
20void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
21 [SIGTRAP] = relay_signal,
22 [SIGFPE] = relay_signal,
23 [SIGILL] = relay_signal,
24 [SIGWINCH] = winch,
25 [SIGBUS] = bus_handler,
26 [SIGSEGV] = segv_handler,
27 [SIGIO] = sigio_handler,
28 [SIGALRM] = timer_handler
29};
30
31static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
32{
33 struct uml_pt_regs *r;
34 int save_errno = errno;
35
36 r = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
37 if (!r)
38 panic("out of memory");
39
40 r->is_user = 0;
41 if (sig == SIGSEGV) {
42
43 get_regs_from_mc(r, mc);
44 GET_FAULTINFO_FROM_MC(r->faultinfo, mc);
45 }
46
47
48 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
49 unblock_signals();
50
51 (*sig_info[sig])(sig, si, r);
52
53 errno = save_errno;
54
55 free(r);
56}
57
58
59
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61
62
63
64#define SIGIO_BIT 0
65#define SIGIO_MASK (1 << SIGIO_BIT)
66
67#define SIGALRM_BIT 1
68#define SIGALRM_MASK (1 << SIGALRM_BIT)
69
70static int signals_enabled;
71static unsigned int signals_pending;
72static unsigned int signals_active = 0;
73
74void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
75{
76 int enabled;
77
78 enabled = signals_enabled;
79 if (!enabled && (sig == SIGIO)) {
80 signals_pending |= SIGIO_MASK;
81 return;
82 }
83
84 block_signals();
85
86 sig_handler_common(sig, si, mc);
87
88 set_signals(enabled);
89}
90
91static void timer_real_alarm_handler(mcontext_t *mc)
92{
93 struct uml_pt_regs *regs;
94
95 regs = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
96 if (!regs)
97 panic("out of memory");
98
99 if (mc != NULL)
100 get_regs_from_mc(regs, mc);
101 timer_handler(SIGALRM, NULL, regs);
102
103 free(regs);
104}
105
106void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
107{
108 int enabled;
109
110 enabled = signals_enabled;
111 if (!signals_enabled) {
112 signals_pending |= SIGALRM_MASK;
113 return;
114 }
115
116 block_signals();
117
118 signals_active |= SIGALRM_MASK;
119
120 timer_real_alarm_handler(mc);
121
122 signals_active &= ~SIGALRM_MASK;
123
124 set_signals(enabled);
125}
126
127void deliver_alarm(void) {
128 timer_alarm_handler(SIGALRM, NULL, NULL);
129}
130
131void timer_set_signal_handler(void)
132{
133 set_handler(SIGALRM);
134}
135
136void set_sigstack(void *sig_stack, int size)
137{
138 stack_t stack = {
139 .ss_flags = 0,
140 .ss_sp = sig_stack,
141 .ss_size = size - sizeof(void *)
142 };
143
144 if (sigaltstack(&stack, NULL) != 0)
145 panic("enabling signal stack failed, errno = %d\n", errno);
146}
147
148static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
149 [SIGSEGV] = sig_handler,
150 [SIGBUS] = sig_handler,
151 [SIGILL] = sig_handler,
152 [SIGFPE] = sig_handler,
153 [SIGTRAP] = sig_handler,
154
155 [SIGIO] = sig_handler,
156 [SIGWINCH] = sig_handler,
157 [SIGALRM] = timer_alarm_handler
158};
159
160static void hard_handler(int sig, siginfo_t *si, void *p)
161{
162 struct ucontext *uc = p;
163 mcontext_t *mc = &uc->uc_mcontext;
164 unsigned long pending = 1UL << sig;
165
166 do {
167 int nested, bail;
168
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178
179 bail = to_irq_stack(&pending);
180 if (bail)
181 return;
182
183 nested = pending & 1;
184 pending &= ~1;
185
186 while ((sig = ffs(pending)) != 0){
187 sig--;
188 pending &= ~(1 << sig);
189 (*handlers[sig])(sig, (struct siginfo *)si, mc);
190 }
191
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195
196
197
198 if (!nested)
199 pending = from_irq_stack(nested);
200 } while (pending);
201}
202
203void set_handler(int sig)
204{
205 struct sigaction action;
206 int flags = SA_SIGINFO | SA_ONSTACK;
207 sigset_t sig_mask;
208
209 action.sa_sigaction = hard_handler;
210
211
212 sigemptyset(&action.sa_mask);
213 sigaddset(&action.sa_mask, SIGIO);
214 sigaddset(&action.sa_mask, SIGWINCH);
215 sigaddset(&action.sa_mask, SIGALRM);
216
217 if (sig == SIGSEGV)
218 flags |= SA_NODEFER;
219
220 if (sigismember(&action.sa_mask, sig))
221 flags |= SA_RESTART;
222
223 action.sa_flags = flags;
224 action.sa_restorer = NULL;
225 if (sigaction(sig, &action, NULL) < 0)
226 panic("sigaction failed - errno = %d\n", errno);
227
228 sigemptyset(&sig_mask);
229 sigaddset(&sig_mask, sig);
230 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
231 panic("sigprocmask failed - errno = %d\n", errno);
232}
233
234int change_sig(int signal, int on)
235{
236 sigset_t sigset;
237
238 sigemptyset(&sigset);
239 sigaddset(&sigset, signal);
240 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
241 return -errno;
242
243 return 0;
244}
245
246void block_signals(void)
247{
248 signals_enabled = 0;
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253
254
255 barrier();
256}
257
258void unblock_signals(void)
259{
260 int save_pending;
261
262 if (signals_enabled == 1)
263 return;
264
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267
268
269
270 while (1) {
271
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275 signals_enabled = 1;
276
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280
281 barrier();
282
283 save_pending = signals_pending;
284 if (save_pending == 0)
285 return;
286
287 signals_pending = 0;
288
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294
295 signals_enabled = 0;
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304
305 if (save_pending & SIGIO_MASK)
306 sig_handler_common(SIGIO, NULL, NULL);
307
308
309
310 if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
311 timer_real_alarm_handler(NULL);
312
313
314
315 if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
316 return;
317
318 }
319}
320
321int get_signals(void)
322{
323 return signals_enabled;
324}
325
326int set_signals(int enable)
327{
328 int ret;
329 if (signals_enabled == enable)
330 return enable;
331
332 ret = signals_enabled;
333 if (enable)
334 unblock_signals();
335 else block_signals();
336
337 return ret;
338}
339
340int os_is_signal_stack(void)
341{
342 stack_t ss;
343 sigaltstack(NULL, &ss);
344
345 return ss.ss_flags & SS_ONSTACK;
346}
347