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1da177e4 | 1 | /* |
2eb5f31b AI |
2 | * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk}) |
3 | * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) | |
1da177e4 | 4 | * Copyright (C) 2004 PathScale, Inc |
ba180fd4 | 5 | * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
1da177e4 LT |
6 | * Licensed under the GPL |
7 | */ | |
8 | ||
0805d89c | 9 | #include <stdlib.h> |
0805d89c | 10 | #include <stdarg.h> |
ba180fd4 JD |
11 | #include <errno.h> |
12 | #include <signal.h> | |
13 | #include <strings.h> | |
37185b33 AV |
14 | #include <as-layout.h> |
15 | #include <kern_util.h> | |
16 | #include <os.h> | |
17 | #include <sysdep/mcontext.h> | |
57a05d83 | 18 | #include <um_malloc.h> |
1da177e4 | 19 | |
72383d43 | 20 | void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { |
75ada8ff JD |
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, | |
2eb5f31b AI |
28 | [SIGALRM] = timer_handler |
29 | }; | |
75ada8ff | 30 | |
9a8c1359 | 31 | static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) |
75ada8ff | 32 | { |
b6024b21 | 33 | struct uml_pt_regs *r; |
e6a2d1f7 | 34 | int save_errno = errno; |
75ada8ff | 35 | |
57a05d83 | 36 | r = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC); |
b6024b21 EC |
37 | if (!r) |
38 | panic("out of memory"); | |
39 | ||
40 | r->is_user = 0; | |
75ada8ff | 41 | if (sig == SIGSEGV) { |
e6a2d1f7 | 42 | /* For segfaults, we want the data from the sigcontext. */ |
b6024b21 EC |
43 | get_regs_from_mc(r, mc); |
44 | GET_FAULTINFO_FROM_MC(r->faultinfo, mc); | |
e6a2d1f7 | 45 | } |
75ada8ff | 46 | |
e6a2d1f7 | 47 | /* enable signals if sig isn't IRQ signal */ |
2eb5f31b | 48 | if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM)) |
75ada8ff JD |
49 | unblock_signals(); |
50 | ||
b6024b21 | 51 | (*sig_info[sig])(sig, si, r); |
75ada8ff JD |
52 | |
53 | errno = save_errno; | |
b6024b21 EC |
54 | |
55 | free(r); | |
75ada8ff JD |
56 | } |
57 | ||
ba180fd4 | 58 | /* |
61b63c55 | 59 | * These are the asynchronous signals. SIGPROF is excluded because we want to |
1d7173ba JD |
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 | ||
2eb5f31b AI |
67 | #define SIGALRM_BIT 1 |
68 | #define SIGALRM_MASK (1 << SIGALRM_BIT) | |
1d7173ba | 69 | |
fce8c41c | 70 | static int signals_enabled; |
cfef8f34 | 71 | static unsigned int signals_pending; |
d5e3f5cb | 72 | static unsigned int signals_active = 0; |
1d7173ba | 73 | |
9a8c1359 | 74 | void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) |
1da177e4 | 75 | { |
1d7173ba JD |
76 | int enabled; |
77 | ||
1d7173ba | 78 | enabled = signals_enabled; |
ba180fd4 | 79 | if (!enabled && (sig == SIGIO)) { |
cfef8f34 | 80 | signals_pending |= SIGIO_MASK; |
1d7173ba JD |
81 | return; |
82 | } | |
83 | ||
84 | block_signals(); | |
85 | ||
d3c1cfcd | 86 | sig_handler_common(sig, si, mc); |
1d7173ba JD |
87 | |
88 | set_signals(enabled); | |
1da177e4 LT |
89 | } |
90 | ||
2eb5f31b | 91 | static void timer_real_alarm_handler(mcontext_t *mc) |
1da177e4 | 92 | { |
b6024b21 EC |
93 | struct uml_pt_regs *regs; |
94 | ||
57a05d83 | 95 | regs = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC); |
b6024b21 EC |
96 | if (!regs) |
97 | panic("out of memory"); | |
2ea5bc5e | 98 | |
248b74c7 | 99 | if (mc != NULL) |
b6024b21 EC |
100 | get_regs_from_mc(regs, mc); |
101 | timer_handler(SIGALRM, NULL, regs); | |
102 | ||
103 | free(regs); | |
1d7173ba JD |
104 | } |
105 | ||
2eb5f31b | 106 | void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) |
1d7173ba | 107 | { |
1d7173ba JD |
108 | int enabled; |
109 | ||
1d7173ba | 110 | enabled = signals_enabled; |
ba180fd4 | 111 | if (!signals_enabled) { |
2eb5f31b | 112 | signals_pending |= SIGALRM_MASK; |
1d7173ba JD |
113 | return; |
114 | } | |
115 | ||
116 | block_signals(); | |
117 | ||
d5e3f5cb AI |
118 | signals_active |= SIGALRM_MASK; |
119 | ||
2eb5f31b | 120 | timer_real_alarm_handler(mc); |
d5e3f5cb AI |
121 | |
122 | signals_active &= ~SIGALRM_MASK; | |
123 | ||
1d7173ba | 124 | set_signals(enabled); |
1da177e4 LT |
125 | } |
126 | ||
2eb5f31b AI |
127 | void deliver_alarm(void) { |
128 | timer_alarm_handler(SIGALRM, NULL, NULL); | |
129 | } | |
130 | ||
131 | void timer_set_signal_handler(void) | |
78a26e25 | 132 | { |
2eb5f31b | 133 | set_handler(SIGALRM); |
78a26e25 JD |
134 | } |
135 | ||
0805d89c GS |
136 | void set_sigstack(void *sig_stack, int size) |
137 | { | |
9a75551a HWH |
138 | stack_t stack = { |
139 | .ss_flags = 0, | |
140 | .ss_sp = sig_stack, | |
141 | .ss_size = size - sizeof(void *) | |
142 | }; | |
0805d89c | 143 | |
ba180fd4 | 144 | if (sigaltstack(&stack, NULL) != 0) |
0805d89c GS |
145 | panic("enabling signal stack failed, errno = %d\n", errno); |
146 | } | |
147 | ||
9a8c1359 | 148 | static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = { |
00361683 AV |
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, | |
2eb5f31b | 157 | [SIGALRM] = timer_alarm_handler |
00361683 | 158 | }; |
4b84c69b | 159 | |
d3c1cfcd | 160 | static void hard_handler(int sig, siginfo_t *si, void *p) |
c14b8494 | 161 | { |
248b74c7 AV |
162 | struct ucontext *uc = p; |
163 | mcontext_t *mc = &uc->uc_mcontext; | |
508a9274 | 164 | unsigned long pending = 1UL << sig; |
c14b8494 JD |
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 | */ | |
508a9274 | 179 | bail = to_irq_stack(&pending); |
ba180fd4 | 180 | if (bail) |
c14b8494 JD |
181 | return; |
182 | ||
183 | nested = pending & 1; | |
184 | pending &= ~1; | |
185 | ||
ba180fd4 | 186 | while ((sig = ffs(pending)) != 0){ |
c14b8494 JD |
187 | sig--; |
188 | pending &= ~(1 << sig); | |
9a8c1359 | 189 | (*handlers[sig])(sig, (struct siginfo *)si, mc); |
c14b8494 JD |
190 | } |
191 | ||
ba180fd4 JD |
192 | /* |
193 | * Again, pending comes back with a mask of signals | |
c14b8494 JD |
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 | */ | |
ba180fd4 | 198 | if (!nested) |
c14b8494 | 199 | pending = from_irq_stack(nested); |
ba180fd4 | 200 | } while (pending); |
c14b8494 JD |
201 | } |
202 | ||
00361683 | 203 | void set_handler(int sig) |
0805d89c GS |
204 | { |
205 | struct sigaction action; | |
e87df986 | 206 | int flags = SA_SIGINFO | SA_ONSTACK; |
1d7173ba | 207 | sigset_t sig_mask; |
0805d89c | 208 | |
7eb12255 | 209 | action.sa_sigaction = hard_handler; |
4b84c69b | 210 | |
e87df986 | 211 | /* block irq ones */ |
0805d89c | 212 | sigemptyset(&action.sa_mask); |
e87df986 AV |
213 | sigaddset(&action.sa_mask, SIGIO); |
214 | sigaddset(&action.sa_mask, SIGWINCH); | |
2eb5f31b | 215 | sigaddset(&action.sa_mask, SIGALRM); |
4b84c69b | 216 | |
e6a2d1f7 JD |
217 | if (sig == SIGSEGV) |
218 | flags |= SA_NODEFER; | |
219 | ||
e87df986 AV |
220 | if (sigismember(&action.sa_mask, sig)) |
221 | flags |= SA_RESTART; /* if it's an irq signal */ | |
222 | ||
223 | action.sa_flags = flags; | |
0805d89c | 224 | action.sa_restorer = NULL; |
ba180fd4 | 225 | if (sigaction(sig, &action, NULL) < 0) |
1d7173ba JD |
226 | panic("sigaction failed - errno = %d\n", errno); |
227 | ||
228 | sigemptyset(&sig_mask); | |
229 | sigaddset(&sig_mask, sig); | |
ba180fd4 | 230 | if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) |
1d7173ba | 231 | panic("sigprocmask failed - errno = %d\n", errno); |
0805d89c GS |
232 | } |
233 | ||
234 | int change_sig(int signal, int on) | |
235 | { | |
cfef8f34 | 236 | sigset_t sigset; |
0805d89c GS |
237 | |
238 | sigemptyset(&sigset); | |
239 | sigaddset(&sigset, signal); | |
cfef8f34 | 240 | if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) |
c9a3072d | 241 | return -errno; |
cfef8f34 JD |
242 | |
243 | return 0; | |
0805d89c GS |
244 | } |
245 | ||
0805d89c GS |
246 | void block_signals(void) |
247 | { | |
1d7173ba | 248 | signals_enabled = 0; |
ba180fd4 JD |
249 | /* |
250 | * This must return with signals disabled, so this barrier | |
53b17332 JD |
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 | */ | |
fce8c41c | 255 | barrier(); |
0805d89c GS |
256 | } |
257 | ||
258 | void unblock_signals(void) | |
259 | { | |
1d7173ba | 260 | int save_pending; |
0805d89c | 261 | |
ba180fd4 | 262 | if (signals_enabled == 1) |
1d7173ba | 263 | return; |
0805d89c | 264 | |
ba180fd4 JD |
265 | /* |
266 | * We loop because the IRQ handler returns with interrupts off. So, | |
1d7173ba | 267 | * interrupts may have arrived and we need to re-enable them and |
cfef8f34 | 268 | * recheck signals_pending. |
1d7173ba | 269 | */ |
5134d8fe | 270 | while (1) { |
ba180fd4 JD |
271 | /* |
272 | * Save and reset save_pending after enabling signals. This | |
cfef8f34 | 273 | * way, signals_pending won't be changed while we're reading it. |
1d7173ba JD |
274 | */ |
275 | signals_enabled = 1; | |
276 | ||
ba180fd4 | 277 | /* |
cfef8f34 | 278 | * Setting signals_enabled and reading signals_pending must |
53b17332 JD |
279 | * happen in this order. |
280 | */ | |
fce8c41c | 281 | barrier(); |
53b17332 | 282 | |
cfef8f34 | 283 | save_pending = signals_pending; |
fce8c41c | 284 | if (save_pending == 0) |
1d7173ba JD |
285 | return; |
286 | ||
cfef8f34 | 287 | signals_pending = 0; |
1d7173ba | 288 | |
ba180fd4 JD |
289 | /* |
290 | * We have pending interrupts, so disable signals, as the | |
1d7173ba JD |
291 | * handlers expect them off when they are called. They will |
292 | * be enabled again above. | |
293 | */ | |
294 | ||
295 | signals_enabled = 0; | |
296 | ||
ba180fd4 JD |
297 | /* |
298 | * Deal with SIGIO first because the alarm handler might | |
1d7173ba JD |
299 | * schedule, leaving the pending SIGIO stranded until we come |
300 | * back here. | |
d3c1cfcd MP |
301 | * |
302 | * SIGIO's handler doesn't use siginfo or mcontext, | |
303 | * so they can be NULL. | |
1d7173ba | 304 | */ |
ba180fd4 | 305 | if (save_pending & SIGIO_MASK) |
d3c1cfcd | 306 | sig_handler_common(SIGIO, NULL, NULL); |
1d7173ba | 307 | |
d5e3f5cb AI |
308 | /* Do not reenter the handler */ |
309 | ||
310 | if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK))) | |
2eb5f31b | 311 | timer_real_alarm_handler(NULL); |
d5e3f5cb AI |
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 | ||
1d7173ba | 318 | } |
0805d89c GS |
319 | } |
320 | ||
321 | int get_signals(void) | |
322 | { | |
1d7173ba | 323 | return signals_enabled; |
0805d89c GS |
324 | } |
325 | ||
326 | int set_signals(int enable) | |
327 | { | |
0805d89c | 328 | int ret; |
ba180fd4 | 329 | if (signals_enabled == enable) |
1d7173ba | 330 | return enable; |
0805d89c | 331 | |
1d7173ba | 332 | ret = signals_enabled; |
ba180fd4 | 333 | if (enable) |
1d7173ba JD |
334 | unblock_signals(); |
335 | else block_signals(); | |
0805d89c | 336 | |
1d7173ba | 337 | return ret; |
0805d89c | 338 | } |
f72c22e4 RW |
339 | |
340 | int os_is_signal_stack(void) | |
341 | { | |
342 | stack_t ss; | |
343 | sigaltstack(NULL, &ss); | |
344 | ||
345 | return ss.ss_flags & SS_ONSTACK; | |
346 | } |