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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2004 PathScale, Inc | |
ba180fd4 | 3 | * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
1da177e4 LT |
4 | * Licensed under the GPL |
5 | */ | |
6 | ||
0805d89c | 7 | #include <stdlib.h> |
0805d89c | 8 | #include <stdarg.h> |
ba180fd4 JD |
9 | #include <errno.h> |
10 | #include <signal.h> | |
11 | #include <strings.h> | |
37185b33 AV |
12 | #include <as-layout.h> |
13 | #include <kern_util.h> | |
14 | #include <os.h> | |
15 | #include <sysdep/mcontext.h> | |
d3c1cfcd | 16 | #include "internal.h" |
1da177e4 | 17 | |
72383d43 | 18 | void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { |
75ada8ff JD |
19 | [SIGTRAP] = relay_signal, |
20 | [SIGFPE] = relay_signal, | |
21 | [SIGILL] = relay_signal, | |
22 | [SIGWINCH] = winch, | |
23 | [SIGBUS] = bus_handler, | |
24 | [SIGSEGV] = segv_handler, | |
25 | [SIGIO] = sigio_handler, | |
26 | [SIGVTALRM] = timer_handler }; | |
27 | ||
d3c1cfcd | 28 | static void sig_handler_common(int sig, siginfo_t *si, mcontext_t *mc) |
75ada8ff | 29 | { |
e6a2d1f7 JD |
30 | struct uml_pt_regs r; |
31 | int save_errno = errno; | |
75ada8ff | 32 | |
e6a2d1f7 | 33 | r.is_user = 0; |
75ada8ff | 34 | if (sig == SIGSEGV) { |
e6a2d1f7 | 35 | /* For segfaults, we want the data from the sigcontext. */ |
ab1c0cc7 | 36 | get_regs_from_mc(&r, mc); |
248b74c7 | 37 | GET_FAULTINFO_FROM_MC(r.faultinfo, mc); |
e6a2d1f7 | 38 | } |
75ada8ff | 39 | |
e6a2d1f7 | 40 | /* enable signals if sig isn't IRQ signal */ |
75ada8ff JD |
41 | if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM)) |
42 | unblock_signals(); | |
43 | ||
d3c1cfcd | 44 | (*sig_info[sig])(sig, si, &r); |
75ada8ff JD |
45 | |
46 | errno = save_errno; | |
75ada8ff JD |
47 | } |
48 | ||
ba180fd4 | 49 | /* |
61b63c55 | 50 | * These are the asynchronous signals. SIGPROF is excluded because we want to |
1d7173ba JD |
51 | * be able to profile all of UML, not just the non-critical sections. If |
52 | * profiling is not thread-safe, then that is not my problem. We can disable | |
53 | * profiling when SMP is enabled in that case. | |
54 | */ | |
55 | #define SIGIO_BIT 0 | |
56 | #define SIGIO_MASK (1 << SIGIO_BIT) | |
57 | ||
58 | #define SIGVTALRM_BIT 1 | |
59 | #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT) | |
60 | ||
fce8c41c | 61 | static int signals_enabled; |
cfef8f34 | 62 | static unsigned int signals_pending; |
1d7173ba | 63 | |
d3c1cfcd | 64 | void sig_handler(int sig, siginfo_t *si, mcontext_t *mc) |
1da177e4 | 65 | { |
1d7173ba JD |
66 | int enabled; |
67 | ||
1d7173ba | 68 | enabled = signals_enabled; |
ba180fd4 | 69 | if (!enabled && (sig == SIGIO)) { |
cfef8f34 | 70 | signals_pending |= SIGIO_MASK; |
1d7173ba JD |
71 | return; |
72 | } | |
73 | ||
74 | block_signals(); | |
75 | ||
d3c1cfcd | 76 | sig_handler_common(sig, si, mc); |
1d7173ba JD |
77 | |
78 | set_signals(enabled); | |
1da177e4 LT |
79 | } |
80 | ||
248b74c7 | 81 | static void real_alarm_handler(mcontext_t *mc) |
1da177e4 | 82 | { |
77bf4400 | 83 | struct uml_pt_regs regs; |
2ea5bc5e | 84 | |
248b74c7 | 85 | if (mc != NULL) |
ab1c0cc7 | 86 | get_regs_from_mc(®s, mc); |
77bf4400 | 87 | regs.is_user = 0; |
2ea5bc5e | 88 | unblock_signals(); |
d3c1cfcd | 89 | timer_handler(SIGVTALRM, NULL, ®s); |
1d7173ba JD |
90 | } |
91 | ||
d3c1cfcd | 92 | void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) |
1d7173ba | 93 | { |
1d7173ba JD |
94 | int enabled; |
95 | ||
1d7173ba | 96 | enabled = signals_enabled; |
ba180fd4 | 97 | if (!signals_enabled) { |
cfef8f34 | 98 | signals_pending |= SIGVTALRM_MASK; |
1d7173ba JD |
99 | return; |
100 | } | |
101 | ||
102 | block_signals(); | |
103 | ||
248b74c7 | 104 | real_alarm_handler(mc); |
1d7173ba | 105 | set_signals(enabled); |
1da177e4 LT |
106 | } |
107 | ||
78a26e25 JD |
108 | void timer_init(void) |
109 | { | |
00361683 | 110 | set_handler(SIGVTALRM); |
78a26e25 JD |
111 | } |
112 | ||
0805d89c GS |
113 | void set_sigstack(void *sig_stack, int size) |
114 | { | |
115 | stack_t stack = ((stack_t) { .ss_flags = 0, | |
116 | .ss_sp = (__ptr_t) sig_stack, | |
117 | .ss_size = size - sizeof(void *) }); | |
118 | ||
ba180fd4 | 119 | if (sigaltstack(&stack, NULL) != 0) |
0805d89c GS |
120 | panic("enabling signal stack failed, errno = %d\n", errno); |
121 | } | |
122 | ||
d3c1cfcd | 123 | static void (*handlers[_NSIG])(int sig, siginfo_t *si, mcontext_t *mc) = { |
00361683 AV |
124 | [SIGSEGV] = sig_handler, |
125 | [SIGBUS] = sig_handler, | |
126 | [SIGILL] = sig_handler, | |
127 | [SIGFPE] = sig_handler, | |
128 | [SIGTRAP] = sig_handler, | |
129 | ||
130 | [SIGIO] = sig_handler, | |
131 | [SIGWINCH] = sig_handler, | |
132 | [SIGVTALRM] = alarm_handler | |
133 | }; | |
4b84c69b | 134 | |
248b74c7 | 135 | |
d3c1cfcd | 136 | static void hard_handler(int sig, siginfo_t *si, void *p) |
c14b8494 | 137 | { |
248b74c7 AV |
138 | struct ucontext *uc = p; |
139 | mcontext_t *mc = &uc->uc_mcontext; | |
508a9274 | 140 | unsigned long pending = 1UL << sig; |
c14b8494 JD |
141 | |
142 | do { | |
143 | int nested, bail; | |
144 | ||
145 | /* | |
146 | * pending comes back with one bit set for each | |
147 | * interrupt that arrived while setting up the stack, | |
148 | * plus a bit for this interrupt, plus the zero bit is | |
149 | * set if this is a nested interrupt. | |
150 | * If bail is true, then we interrupted another | |
151 | * handler setting up the stack. In this case, we | |
152 | * have to return, and the upper handler will deal | |
153 | * with this interrupt. | |
154 | */ | |
508a9274 | 155 | bail = to_irq_stack(&pending); |
ba180fd4 | 156 | if (bail) |
c14b8494 JD |
157 | return; |
158 | ||
159 | nested = pending & 1; | |
160 | pending &= ~1; | |
161 | ||
ba180fd4 | 162 | while ((sig = ffs(pending)) != 0){ |
c14b8494 JD |
163 | sig--; |
164 | pending &= ~(1 << sig); | |
d3c1cfcd | 165 | (*handlers[sig])(sig, si, mc); |
c14b8494 JD |
166 | } |
167 | ||
ba180fd4 JD |
168 | /* |
169 | * Again, pending comes back with a mask of signals | |
c14b8494 JD |
170 | * that arrived while tearing down the stack. If this |
171 | * is non-zero, we just go back, set up the stack | |
172 | * again, and handle the new interrupts. | |
173 | */ | |
ba180fd4 | 174 | if (!nested) |
c14b8494 | 175 | pending = from_irq_stack(nested); |
ba180fd4 | 176 | } while (pending); |
c14b8494 JD |
177 | } |
178 | ||
00361683 | 179 | void set_handler(int sig) |
0805d89c GS |
180 | { |
181 | struct sigaction action; | |
e87df986 | 182 | int flags = SA_SIGINFO | SA_ONSTACK; |
1d7173ba | 183 | sigset_t sig_mask; |
0805d89c | 184 | |
7eb12255 | 185 | action.sa_sigaction = hard_handler; |
4b84c69b | 186 | |
e87df986 | 187 | /* block irq ones */ |
0805d89c | 188 | sigemptyset(&action.sa_mask); |
e87df986 AV |
189 | sigaddset(&action.sa_mask, SIGVTALRM); |
190 | sigaddset(&action.sa_mask, SIGIO); | |
191 | sigaddset(&action.sa_mask, SIGWINCH); | |
4b84c69b | 192 | |
e6a2d1f7 JD |
193 | if (sig == SIGSEGV) |
194 | flags |= SA_NODEFER; | |
195 | ||
e87df986 AV |
196 | if (sigismember(&action.sa_mask, sig)) |
197 | flags |= SA_RESTART; /* if it's an irq signal */ | |
198 | ||
199 | action.sa_flags = flags; | |
0805d89c | 200 | action.sa_restorer = NULL; |
ba180fd4 | 201 | if (sigaction(sig, &action, NULL) < 0) |
1d7173ba JD |
202 | panic("sigaction failed - errno = %d\n", errno); |
203 | ||
204 | sigemptyset(&sig_mask); | |
205 | sigaddset(&sig_mask, sig); | |
ba180fd4 | 206 | if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) |
1d7173ba | 207 | panic("sigprocmask failed - errno = %d\n", errno); |
0805d89c GS |
208 | } |
209 | ||
210 | int change_sig(int signal, int on) | |
211 | { | |
cfef8f34 | 212 | sigset_t sigset; |
0805d89c GS |
213 | |
214 | sigemptyset(&sigset); | |
215 | sigaddset(&sigset, signal); | |
cfef8f34 | 216 | if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) |
c9a3072d | 217 | return -errno; |
cfef8f34 JD |
218 | |
219 | return 0; | |
0805d89c GS |
220 | } |
221 | ||
0805d89c GS |
222 | void block_signals(void) |
223 | { | |
1d7173ba | 224 | signals_enabled = 0; |
ba180fd4 JD |
225 | /* |
226 | * This must return with signals disabled, so this barrier | |
53b17332 JD |
227 | * ensures that writes are flushed out before the return. |
228 | * This might matter if gcc figures out how to inline this and | |
229 | * decides to shuffle this code into the caller. | |
230 | */ | |
fce8c41c | 231 | barrier(); |
0805d89c GS |
232 | } |
233 | ||
234 | void unblock_signals(void) | |
235 | { | |
1d7173ba | 236 | int save_pending; |
0805d89c | 237 | |
ba180fd4 | 238 | if (signals_enabled == 1) |
1d7173ba | 239 | return; |
0805d89c | 240 | |
ba180fd4 JD |
241 | /* |
242 | * We loop because the IRQ handler returns with interrupts off. So, | |
1d7173ba | 243 | * interrupts may have arrived and we need to re-enable them and |
cfef8f34 | 244 | * recheck signals_pending. |
1d7173ba | 245 | */ |
5134d8fe | 246 | while (1) { |
ba180fd4 JD |
247 | /* |
248 | * Save and reset save_pending after enabling signals. This | |
cfef8f34 | 249 | * way, signals_pending won't be changed while we're reading it. |
1d7173ba JD |
250 | */ |
251 | signals_enabled = 1; | |
252 | ||
ba180fd4 | 253 | /* |
cfef8f34 | 254 | * Setting signals_enabled and reading signals_pending must |
53b17332 JD |
255 | * happen in this order. |
256 | */ | |
fce8c41c | 257 | barrier(); |
53b17332 | 258 | |
cfef8f34 | 259 | save_pending = signals_pending; |
fce8c41c | 260 | if (save_pending == 0) |
1d7173ba JD |
261 | return; |
262 | ||
cfef8f34 | 263 | signals_pending = 0; |
1d7173ba | 264 | |
ba180fd4 JD |
265 | /* |
266 | * We have pending interrupts, so disable signals, as the | |
1d7173ba JD |
267 | * handlers expect them off when they are called. They will |
268 | * be enabled again above. | |
269 | */ | |
270 | ||
271 | signals_enabled = 0; | |
272 | ||
ba180fd4 JD |
273 | /* |
274 | * Deal with SIGIO first because the alarm handler might | |
1d7173ba JD |
275 | * schedule, leaving the pending SIGIO stranded until we come |
276 | * back here. | |
d3c1cfcd MP |
277 | * |
278 | * SIGIO's handler doesn't use siginfo or mcontext, | |
279 | * so they can be NULL. | |
1d7173ba | 280 | */ |
ba180fd4 | 281 | if (save_pending & SIGIO_MASK) |
d3c1cfcd | 282 | sig_handler_common(SIGIO, NULL, NULL); |
1d7173ba | 283 | |
ba180fd4 | 284 | if (save_pending & SIGVTALRM_MASK) |
61b63c55 | 285 | real_alarm_handler(NULL); |
1d7173ba | 286 | } |
0805d89c GS |
287 | } |
288 | ||
289 | int get_signals(void) | |
290 | { | |
1d7173ba | 291 | return signals_enabled; |
0805d89c GS |
292 | } |
293 | ||
294 | int set_signals(int enable) | |
295 | { | |
0805d89c | 296 | int ret; |
ba180fd4 | 297 | if (signals_enabled == enable) |
1d7173ba | 298 | return enable; |
0805d89c | 299 | |
1d7173ba | 300 | ret = signals_enabled; |
ba180fd4 | 301 | if (enable) |
1d7173ba JD |
302 | unblock_signals(); |
303 | else block_signals(); | |
0805d89c | 304 | |
1d7173ba | 305 | return ret; |
0805d89c | 306 | } |