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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
4 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
5 * Copyright (C) 2004 PathScale, Inc
6 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
7 */
8
9#include <stdlib.h>
10#include <stdarg.h>
11#include <errno.h>
12#include <signal.h>
13#include <string.h>
14#include <strings.h>
15#include <as-layout.h>
16#include <kern_util.h>
17#include <os.h>
18#include <sysdep/mcontext.h>
19#include <um_malloc.h>
20#include <sys/ucontext.h>
21#include <timetravel.h>
22
23void (*sig_info[NSIG])(int, struct siginfo *, 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};
32
33static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
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 get_regs_from_mc(&r, mc);
42 GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
43 }
44
45 /* enable signals if sig isn't IRQ signal */
46 if ((sig != SIGIO) && (sig != SIGWINCH))
47 unblock_signals_trace();
48
49 (*sig_info[sig])(sig, si, &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 SIGALRM_BIT 1
64#define SIGALRM_MASK (1 << SIGALRM_BIT)
65
66int signals_enabled;
67#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT
68static int signals_blocked;
69#else
70#define signals_blocked 0
71#endif
72static unsigned int signals_pending;
73static unsigned int signals_active = 0;
74
75void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
76{
77 int enabled = signals_enabled;
78
79 if ((signals_blocked || !enabled) && (sig == SIGIO)) {
80 /*
81 * In TT_MODE_EXTERNAL, need to still call time-travel
82 * handlers unless signals are also blocked for the
83 * external time message processing. This will mark
84 * signals_pending by itself (only if necessary.)
85 */
86 if (!signals_blocked && time_travel_mode == TT_MODE_EXTERNAL)
87 sigio_run_timetravel_handlers();
88 else
89 signals_pending |= SIGIO_MASK;
90 return;
91 }
92
93 block_signals_trace();
94
95 sig_handler_common(sig, si, mc);
96
97 um_set_signals_trace(enabled);
98}
99
100static void timer_real_alarm_handler(mcontext_t *mc)
101{
102 struct uml_pt_regs regs;
103
104 if (mc != NULL)
105 get_regs_from_mc(®s, mc);
106 else
107 memset(®s, 0, sizeof(regs));
108 timer_handler(SIGALRM, NULL, ®s);
109}
110
111void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
112{
113 int enabled;
114
115 enabled = signals_enabled;
116 if (!signals_enabled) {
117 signals_pending |= SIGALRM_MASK;
118 return;
119 }
120
121 block_signals_trace();
122
123 signals_active |= SIGALRM_MASK;
124
125 timer_real_alarm_handler(mc);
126
127 signals_active &= ~SIGALRM_MASK;
128
129 um_set_signals_trace(enabled);
130}
131
132void deliver_alarm(void) {
133 timer_alarm_handler(SIGALRM, NULL, NULL);
134}
135
136void timer_set_signal_handler(void)
137{
138 set_handler(SIGALRM);
139}
140
141void set_sigstack(void *sig_stack, int size)
142{
143 stack_t stack = {
144 .ss_flags = 0,
145 .ss_sp = sig_stack,
146 .ss_size = size
147 };
148
149 if (sigaltstack(&stack, NULL) != 0)
150 panic("enabling signal stack failed, errno = %d\n", errno);
151}
152
153static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
154{
155 uml_pm_wake();
156}
157
158void register_pm_wake_signal(void)
159{
160 set_handler(SIGUSR1);
161}
162
163static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
164 [SIGSEGV] = sig_handler,
165 [SIGBUS] = sig_handler,
166 [SIGILL] = sig_handler,
167 [SIGFPE] = sig_handler,
168 [SIGTRAP] = sig_handler,
169
170 [SIGIO] = sig_handler,
171 [SIGWINCH] = sig_handler,
172 [SIGALRM] = timer_alarm_handler,
173
174 [SIGUSR1] = sigusr1_handler,
175};
176
177static void hard_handler(int sig, siginfo_t *si, void *p)
178{
179 ucontext_t *uc = p;
180 mcontext_t *mc = &uc->uc_mcontext;
181 unsigned long pending = 1UL << sig;
182
183 do {
184 int nested, bail;
185
186 /*
187 * pending comes back with one bit set for each
188 * interrupt that arrived while setting up the stack,
189 * plus a bit for this interrupt, plus the zero bit is
190 * set if this is a nested interrupt.
191 * If bail is true, then we interrupted another
192 * handler setting up the stack. In this case, we
193 * have to return, and the upper handler will deal
194 * with this interrupt.
195 */
196 bail = to_irq_stack(&pending);
197 if (bail)
198 return;
199
200 nested = pending & 1;
201 pending &= ~1;
202
203 while ((sig = ffs(pending)) != 0){
204 sig--;
205 pending &= ~(1 << sig);
206 (*handlers[sig])(sig, (struct siginfo *)si, mc);
207 }
208
209 /*
210 * Again, pending comes back with a mask of signals
211 * that arrived while tearing down the stack. If this
212 * is non-zero, we just go back, set up the stack
213 * again, and handle the new interrupts.
214 */
215 if (!nested)
216 pending = from_irq_stack(nested);
217 } while (pending);
218}
219
220void set_handler(int sig)
221{
222 struct sigaction action;
223 int flags = SA_SIGINFO | SA_ONSTACK;
224 sigset_t sig_mask;
225
226 action.sa_sigaction = hard_handler;
227
228 /* block irq ones */
229 sigemptyset(&action.sa_mask);
230 sigaddset(&action.sa_mask, SIGIO);
231 sigaddset(&action.sa_mask, SIGWINCH);
232 sigaddset(&action.sa_mask, SIGALRM);
233
234 if (sig == SIGSEGV)
235 flags |= SA_NODEFER;
236
237 if (sigismember(&action.sa_mask, sig))
238 flags |= SA_RESTART; /* if it's an irq signal */
239
240 action.sa_flags = flags;
241 action.sa_restorer = NULL;
242 if (sigaction(sig, &action, NULL) < 0)
243 panic("sigaction failed - errno = %d\n", errno);
244
245 sigemptyset(&sig_mask);
246 sigaddset(&sig_mask, sig);
247 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
248 panic("sigprocmask failed - errno = %d\n", errno);
249}
250
251void send_sigio_to_self(void)
252{
253 kill(os_getpid(), SIGIO);
254}
255
256int change_sig(int signal, int on)
257{
258 sigset_t sigset;
259
260 sigemptyset(&sigset);
261 sigaddset(&sigset, signal);
262 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
263 return -errno;
264
265 return 0;
266}
267
268void block_signals(void)
269{
270 signals_enabled = 0;
271 /*
272 * This must return with signals disabled, so this barrier
273 * ensures that writes are flushed out before the return.
274 * This might matter if gcc figures out how to inline this and
275 * decides to shuffle this code into the caller.
276 */
277 barrier();
278}
279
280void unblock_signals(void)
281{
282 int save_pending;
283
284 if (signals_enabled == 1)
285 return;
286
287 signals_enabled = 1;
288#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT
289 deliver_time_travel_irqs();
290#endif
291
292 /*
293 * We loop because the IRQ handler returns with interrupts off. So,
294 * interrupts may have arrived and we need to re-enable them and
295 * recheck signals_pending.
296 */
297 while (1) {
298 /*
299 * Save and reset save_pending after enabling signals. This
300 * way, signals_pending won't be changed while we're reading it.
301 *
302 * Setting signals_enabled and reading signals_pending must
303 * happen in this order, so have the barrier here.
304 */
305 barrier();
306
307 save_pending = signals_pending;
308 if (save_pending == 0)
309 return;
310
311 signals_pending = 0;
312
313 /*
314 * We have pending interrupts, so disable signals, as the
315 * handlers expect them off when they are called. They will
316 * be enabled again above. We need to trace this, as we're
317 * expected to be enabling interrupts already, but any more
318 * tracing that happens inside the handlers we call for the
319 * pending signals will mess up the tracing state.
320 */
321 signals_enabled = 0;
322 um_trace_signals_off();
323
324 /*
325 * Deal with SIGIO first because the alarm handler might
326 * schedule, leaving the pending SIGIO stranded until we come
327 * back here.
328 *
329 * SIGIO's handler doesn't use siginfo or mcontext,
330 * so they can be NULL.
331 */
332 if (save_pending & SIGIO_MASK)
333 sig_handler_common(SIGIO, NULL, NULL);
334
335 /* Do not reenter the handler */
336
337 if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
338 timer_real_alarm_handler(NULL);
339
340 /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
341
342 if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
343 return;
344
345 /* Re-enable signals and trace that we're doing so. */
346 um_trace_signals_on();
347 signals_enabled = 1;
348 }
349}
350
351int um_set_signals(int enable)
352{
353 int ret;
354 if (signals_enabled == enable)
355 return enable;
356
357 ret = signals_enabled;
358 if (enable)
359 unblock_signals();
360 else block_signals();
361
362 return ret;
363}
364
365int um_set_signals_trace(int enable)
366{
367 int ret;
368 if (signals_enabled == enable)
369 return enable;
370
371 ret = signals_enabled;
372 if (enable)
373 unblock_signals_trace();
374 else
375 block_signals_trace();
376
377 return ret;
378}
379
380#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT
381void mark_sigio_pending(void)
382{
383 signals_pending |= SIGIO_MASK;
384}
385
386void block_signals_hard(void)
387{
388 if (signals_blocked)
389 return;
390 signals_blocked = 1;
391 barrier();
392}
393
394void unblock_signals_hard(void)
395{
396 if (!signals_blocked)
397 return;
398 /* Must be set to 0 before we check the pending bits etc. */
399 signals_blocked = 0;
400 barrier();
401
402 if (signals_pending && signals_enabled) {
403 /* this is a bit inefficient, but that's not really important */
404 block_signals();
405 unblock_signals();
406 } else if (signals_pending & SIGIO_MASK) {
407 /* we need to run time-travel handlers even if not enabled */
408 sigio_run_timetravel_handlers();
409 }
410}
411#endif
412
413int os_is_signal_stack(void)
414{
415 stack_t ss;
416 sigaltstack(NULL, &ss);
417
418 return ss.ss_flags & SS_ONSTACK;
419}
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}