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1/*
2 * Copyright (C) 2004 PathScale, Inc
3 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
5 */
6
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/* Copied from linux/compiler-gcc.h since we can't include it directly */
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 /* For segfaults, we want the data from the sigcontext. */
41 copy_sc(&r, sc);
42 GET_FAULTINFO_FROM_SC(r.faultinfo, sc);
43 }
44
45 /* enable signals if sig isn't IRQ signal */
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 * These are the asynchronous signals. SIGPROF is excluded because we want to
56 * be able to profile all of UML, not just the non-critical sections. If
57 * profiling is not thread-safe, then that is not my problem. We can disable
58 * profiling when SMP is enabled in that case.
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
138 /*
139 * pending comes back with one bit set for each
140 * interrupt that arrived while setting up the stack,
141 * plus a bit for this interrupt, plus the zero bit is
142 * set if this is a nested interrupt.
143 * If bail is true, then we interrupted another
144 * handler setting up the stack. In this case, we
145 * have to return, and the upper handler will deal
146 * with this interrupt.
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 * Again, pending comes back with a mask of signals
163 * that arrived while tearing down the stack. If this
164 * is non-zero, we just go back, set up the stack
165 * again, and handle the new interrupts.
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 * This must return with signals disabled, so this barrier
222 * ensures that writes are flushed out before the return.
223 * This might matter if gcc figures out how to inline this and
224 * decides to shuffle this code into the caller.
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 * We loop because the IRQ handler returns with interrupts off. So,
238 * interrupts may have arrived and we need to re-enable them and
239 * recheck signals_pending.
240 */
241 while (1) {
242 /*
243 * Save and reset save_pending after enabling signals. This
244 * way, signals_pending won't be changed while we're reading it.
245 */
246 signals_enabled = 1;
247
248 /*
249 * Setting signals_enabled and reading signals_pending must
250 * happen in this order.
251 */
252 barrier();
253
254 save_pending = signals_pending;
255 if (save_pending == 0)
256 return;
257
258 signals_pending = 0;
259
260 /*
261 * We have pending interrupts, so disable signals, as the
262 * handlers expect them off when they are called. They will
263 * be enabled again above.
264 */
265
266 signals_enabled = 0;
267
268 /*
269 * Deal with SIGIO first because the alarm handler might
270 * schedule, leaving the pending SIGIO stranded until we come
271 * back here.
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}
1/*
2 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
4 * Copyright (C) 2004 PathScale, Inc
5 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
6 * Licensed under the GPL
7 */
8
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 /* For segfaults, we want the data from the sigcontext. */
43 get_regs_from_mc(r, mc);
44 GET_FAULTINFO_FROM_MC(r->faultinfo, mc);
45 }
46
47 /* enable signals if sig isn't IRQ signal */
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 * These are the asynchronous signals. SIGPROF is excluded because we want to
60 * be able to profile all of UML, not just the non-critical sections. If
61 * profiling is not thread-safe, then that is not my problem. We can disable
62 * profiling when SMP is enabled in that case.
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
169 /*
170 * pending comes back with one bit set for each
171 * interrupt that arrived while setting up the stack,
172 * plus a bit for this interrupt, plus the zero bit is
173 * set if this is a nested interrupt.
174 * If bail is true, then we interrupted another
175 * handler setting up the stack. In this case, we
176 * have to return, and the upper handler will deal
177 * with this interrupt.
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
192 /*
193 * Again, pending comes back with a mask of signals
194 * that arrived while tearing down the stack. If this
195 * is non-zero, we just go back, set up the stack
196 * again, and handle the new interrupts.
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 /* block irq ones */
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; /* if it's an irq signal */
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;
249 /*
250 * This must return with signals disabled, so this barrier
251 * ensures that writes are flushed out before the return.
252 * This might matter if gcc figures out how to inline this and
253 * decides to shuffle this code into the caller.
254 */
255 barrier();
256}
257
258void unblock_signals(void)
259{
260 int save_pending;
261
262 if (signals_enabled == 1)
263 return;
264
265 /*
266 * We loop because the IRQ handler returns with interrupts off. So,
267 * interrupts may have arrived and we need to re-enable them and
268 * recheck signals_pending.
269 */
270 while (1) {
271 /*
272 * Save and reset save_pending after enabling signals. This
273 * way, signals_pending won't be changed while we're reading it.
274 */
275 signals_enabled = 1;
276
277 /*
278 * Setting signals_enabled and reading signals_pending must
279 * happen in this order.
280 */
281 barrier();
282
283 save_pending = signals_pending;
284 if (save_pending == 0)
285 return;
286
287 signals_pending = 0;
288
289 /*
290 * We have pending interrupts, so disable signals, as the
291 * handlers expect them off when they are called. They will
292 * be enabled again above.
293 */
294
295 signals_enabled = 0;
296
297 /*
298 * Deal with SIGIO first because the alarm handler might
299 * schedule, leaving the pending SIGIO stranded until we come
300 * back here.
301 *
302 * SIGIO's handler doesn't use siginfo or mcontext,
303 * so they can be NULL.
304 */
305 if (save_pending & SIGIO_MASK)
306 sig_handler_common(SIGIO, NULL, NULL);
307
308 /* Do not reenter the handler */
309
310 if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
311 timer_real_alarm_handler(NULL);
312
313 /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
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}