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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 "sysdep/mcontext.h"
16
17void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
18 [SIGTRAP] = relay_signal,
19 [SIGFPE] = relay_signal,
20 [SIGILL] = relay_signal,
21 [SIGWINCH] = winch,
22 [SIGBUS] = bus_handler,
23 [SIGSEGV] = segv_handler,
24 [SIGIO] = sigio_handler,
25 [SIGVTALRM] = timer_handler };
26
27static void sig_handler_common(int sig, mcontext_t *mc)
28{
29 struct uml_pt_regs r;
30 int save_errno = errno;
31
32 r.is_user = 0;
33 if (sig == SIGSEGV) {
34 /* For segfaults, we want the data from the sigcontext. */
35 get_regs_from_mc(&r, mc);
36 GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
37 }
38
39 /* enable signals if sig isn't IRQ signal */
40 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
41 unblock_signals();
42
43 (*sig_info[sig])(sig, &r);
44
45 errno = save_errno;
46}
47
48/*
49 * These are the asynchronous signals. SIGPROF is excluded because we want to
50 * be able to profile all of UML, not just the non-critical sections. If
51 * profiling is not thread-safe, then that is not my problem. We can disable
52 * profiling when SMP is enabled in that case.
53 */
54#define SIGIO_BIT 0
55#define SIGIO_MASK (1 << SIGIO_BIT)
56
57#define SIGVTALRM_BIT 1
58#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
59
60static int signals_enabled;
61static unsigned int signals_pending;
62
63void sig_handler(int sig, mcontext_t *mc)
64{
65 int enabled;
66
67 enabled = signals_enabled;
68 if (!enabled && (sig == SIGIO)) {
69 signals_pending |= SIGIO_MASK;
70 return;
71 }
72
73 block_signals();
74
75 sig_handler_common(sig, mc);
76
77 set_signals(enabled);
78}
79
80static void real_alarm_handler(mcontext_t *mc)
81{
82 struct uml_pt_regs regs;
83
84 if (mc != NULL)
85 get_regs_from_mc(®s, mc);
86 regs.is_user = 0;
87 unblock_signals();
88 timer_handler(SIGVTALRM, ®s);
89}
90
91void alarm_handler(int sig, mcontext_t *mc)
92{
93 int enabled;
94
95 enabled = signals_enabled;
96 if (!signals_enabled) {
97 signals_pending |= SIGVTALRM_MASK;
98 return;
99 }
100
101 block_signals();
102
103 real_alarm_handler(mc);
104 set_signals(enabled);
105}
106
107void timer_init(void)
108{
109 set_handler(SIGVTALRM);
110}
111
112void set_sigstack(void *sig_stack, int size)
113{
114 stack_t stack = ((stack_t) { .ss_flags = 0,
115 .ss_sp = (__ptr_t) sig_stack,
116 .ss_size = size - sizeof(void *) });
117
118 if (sigaltstack(&stack, NULL) != 0)
119 panic("enabling signal stack failed, errno = %d\n", errno);
120}
121
122static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = {
123 [SIGSEGV] = sig_handler,
124 [SIGBUS] = sig_handler,
125 [SIGILL] = sig_handler,
126 [SIGFPE] = sig_handler,
127 [SIGTRAP] = sig_handler,
128
129 [SIGIO] = sig_handler,
130 [SIGWINCH] = sig_handler,
131 [SIGVTALRM] = alarm_handler
132};
133
134
135static void hard_handler(int sig, siginfo_t *info, void *p)
136{
137 struct ucontext *uc = p;
138 mcontext_t *mc = &uc->uc_mcontext;
139 unsigned long pending = 1UL << sig;
140
141 do {
142 int nested, bail;
143
144 /*
145 * pending comes back with one bit set for each
146 * interrupt that arrived while setting up the stack,
147 * plus a bit for this interrupt, plus the zero bit is
148 * set if this is a nested interrupt.
149 * If bail is true, then we interrupted another
150 * handler setting up the stack. In this case, we
151 * have to return, and the upper handler will deal
152 * with this interrupt.
153 */
154 bail = to_irq_stack(&pending);
155 if (bail)
156 return;
157
158 nested = pending & 1;
159 pending &= ~1;
160
161 while ((sig = ffs(pending)) != 0){
162 sig--;
163 pending &= ~(1 << sig);
164 (*handlers[sig])(sig, mc);
165 }
166
167 /*
168 * Again, pending comes back with a mask of signals
169 * that arrived while tearing down the stack. If this
170 * is non-zero, we just go back, set up the stack
171 * again, and handle the new interrupts.
172 */
173 if (!nested)
174 pending = from_irq_stack(nested);
175 } while (pending);
176}
177
178void set_handler(int sig)
179{
180 struct sigaction action;
181 int flags = SA_SIGINFO | SA_ONSTACK;
182 sigset_t sig_mask;
183
184 action.sa_sigaction = hard_handler;
185
186 /* block irq ones */
187 sigemptyset(&action.sa_mask);
188 sigaddset(&action.sa_mask, SIGVTALRM);
189 sigaddset(&action.sa_mask, SIGIO);
190 sigaddset(&action.sa_mask, SIGWINCH);
191
192 if (sig == SIGSEGV)
193 flags |= SA_NODEFER;
194
195 if (sigismember(&action.sa_mask, sig))
196 flags |= SA_RESTART; /* if it's an irq signal */
197
198 action.sa_flags = flags;
199 action.sa_restorer = NULL;
200 if (sigaction(sig, &action, NULL) < 0)
201 panic("sigaction failed - errno = %d\n", errno);
202
203 sigemptyset(&sig_mask);
204 sigaddset(&sig_mask, sig);
205 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
206 panic("sigprocmask failed - errno = %d\n", errno);
207}
208
209int change_sig(int signal, int on)
210{
211 sigset_t sigset;
212
213 sigemptyset(&sigset);
214 sigaddset(&sigset, signal);
215 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
216 return -errno;
217
218 return 0;
219}
220
221void block_signals(void)
222{
223 signals_enabled = 0;
224 /*
225 * This must return with signals disabled, so this barrier
226 * ensures that writes are flushed out before the return.
227 * This might matter if gcc figures out how to inline this and
228 * decides to shuffle this code into the caller.
229 */
230 barrier();
231}
232
233void unblock_signals(void)
234{
235 int save_pending;
236
237 if (signals_enabled == 1)
238 return;
239
240 /*
241 * We loop because the IRQ handler returns with interrupts off. So,
242 * interrupts may have arrived and we need to re-enable them and
243 * recheck signals_pending.
244 */
245 while (1) {
246 /*
247 * Save and reset save_pending after enabling signals. This
248 * way, signals_pending won't be changed while we're reading it.
249 */
250 signals_enabled = 1;
251
252 /*
253 * Setting signals_enabled and reading signals_pending must
254 * happen in this order.
255 */
256 barrier();
257
258 save_pending = signals_pending;
259 if (save_pending == 0)
260 return;
261
262 signals_pending = 0;
263
264 /*
265 * We have pending interrupts, so disable signals, as the
266 * handlers expect them off when they are called. They will
267 * be enabled again above.
268 */
269
270 signals_enabled = 0;
271
272 /*
273 * Deal with SIGIO first because the alarm handler might
274 * schedule, leaving the pending SIGIO stranded until we come
275 * back here.
276 */
277 if (save_pending & SIGIO_MASK)
278 sig_handler_common(SIGIO, NULL);
279
280 if (save_pending & SIGVTALRM_MASK)
281 real_alarm_handler(NULL);
282 }
283}
284
285int get_signals(void)
286{
287 return signals_enabled;
288}
289
290int set_signals(int enable)
291{
292 int ret;
293 if (signals_enabled == enable)
294 return enable;
295
296 ret = signals_enabled;
297 if (enable)
298 unblock_signals();
299 else block_signals();
300
301 return ret;
302}
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}