Commit | Line | Data |
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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> | |
75ada8ff | 12 | #include "as-layout.h" |
edea1385 | 13 | #include "kern_util.h" |
cff65c4f | 14 | #include "os.h" |
ab1c0cc7 | 15 | #include "sysdep/mcontext.h" |
1da177e4 | 16 | |
75ada8ff JD |
17 | void (*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 | ||
248b74c7 | 27 | static void sig_handler_common(int sig, mcontext_t *mc) |
75ada8ff | 28 | { |
e6a2d1f7 JD |
29 | struct uml_pt_regs r; |
30 | int save_errno = errno; | |
75ada8ff | 31 | |
e6a2d1f7 | 32 | r.is_user = 0; |
75ada8ff | 33 | if (sig == SIGSEGV) { |
e6a2d1f7 | 34 | /* For segfaults, we want the data from the sigcontext. */ |
ab1c0cc7 | 35 | get_regs_from_mc(&r, mc); |
248b74c7 | 36 | GET_FAULTINFO_FROM_MC(r.faultinfo, mc); |
e6a2d1f7 | 37 | } |
75ada8ff | 38 | |
e6a2d1f7 | 39 | /* enable signals if sig isn't IRQ signal */ |
75ada8ff JD |
40 | if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM)) |
41 | unblock_signals(); | |
42 | ||
e6a2d1f7 | 43 | (*sig_info[sig])(sig, &r); |
75ada8ff JD |
44 | |
45 | errno = save_errno; | |
75ada8ff JD |
46 | } |
47 | ||
ba180fd4 | 48 | /* |
61b63c55 | 49 | * These are the asynchronous signals. SIGPROF is excluded because we want to |
1d7173ba JD |
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 | ||
fce8c41c | 60 | static int signals_enabled; |
cfef8f34 | 61 | static unsigned int signals_pending; |
1d7173ba | 62 | |
248b74c7 | 63 | void sig_handler(int sig, mcontext_t *mc) |
1da177e4 | 64 | { |
1d7173ba JD |
65 | int enabled; |
66 | ||
1d7173ba | 67 | enabled = signals_enabled; |
ba180fd4 | 68 | if (!enabled && (sig == SIGIO)) { |
cfef8f34 | 69 | signals_pending |= SIGIO_MASK; |
1d7173ba JD |
70 | return; |
71 | } | |
72 | ||
73 | block_signals(); | |
74 | ||
248b74c7 | 75 | sig_handler_common(sig, mc); |
1d7173ba JD |
76 | |
77 | set_signals(enabled); | |
1da177e4 LT |
78 | } |
79 | ||
248b74c7 | 80 | static void real_alarm_handler(mcontext_t *mc) |
1da177e4 | 81 | { |
77bf4400 | 82 | struct uml_pt_regs regs; |
2ea5bc5e | 83 | |
248b74c7 | 84 | if (mc != NULL) |
ab1c0cc7 | 85 | get_regs_from_mc(®s, mc); |
77bf4400 | 86 | regs.is_user = 0; |
2ea5bc5e | 87 | unblock_signals(); |
61b63c55 | 88 | timer_handler(SIGVTALRM, ®s); |
1d7173ba JD |
89 | } |
90 | ||
248b74c7 | 91 | void alarm_handler(int sig, mcontext_t *mc) |
1d7173ba | 92 | { |
1d7173ba JD |
93 | int enabled; |
94 | ||
1d7173ba | 95 | enabled = signals_enabled; |
ba180fd4 | 96 | if (!signals_enabled) { |
cfef8f34 | 97 | signals_pending |= SIGVTALRM_MASK; |
1d7173ba JD |
98 | return; |
99 | } | |
100 | ||
101 | block_signals(); | |
102 | ||
248b74c7 | 103 | real_alarm_handler(mc); |
1d7173ba | 104 | set_signals(enabled); |
1da177e4 LT |
105 | } |
106 | ||
78a26e25 JD |
107 | void timer_init(void) |
108 | { | |
00361683 | 109 | set_handler(SIGVTALRM); |
78a26e25 JD |
110 | } |
111 | ||
0805d89c GS |
112 | void 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 | ||
ba180fd4 | 118 | if (sigaltstack(&stack, NULL) != 0) |
0805d89c GS |
119 | panic("enabling signal stack failed, errno = %d\n", errno); |
120 | } | |
121 | ||
248b74c7 | 122 | static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = { |
00361683 AV |
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 | }; | |
4b84c69b | 133 | |
248b74c7 AV |
134 | |
135 | static void hard_handler(int sig, siginfo_t *info, void *p) | |
c14b8494 | 136 | { |
248b74c7 AV |
137 | struct ucontext *uc = p; |
138 | mcontext_t *mc = &uc->uc_mcontext; | |
508a9274 | 139 | unsigned long pending = 1UL << sig; |
c14b8494 JD |
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 | */ | |
508a9274 | 154 | bail = to_irq_stack(&pending); |
ba180fd4 | 155 | if (bail) |
c14b8494 JD |
156 | return; |
157 | ||
158 | nested = pending & 1; | |
159 | pending &= ~1; | |
160 | ||
ba180fd4 | 161 | while ((sig = ffs(pending)) != 0){ |
c14b8494 JD |
162 | sig--; |
163 | pending &= ~(1 << sig); | |
248b74c7 | 164 | (*handlers[sig])(sig, mc); |
c14b8494 JD |
165 | } |
166 | ||
ba180fd4 JD |
167 | /* |
168 | * Again, pending comes back with a mask of signals | |
c14b8494 JD |
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 | */ | |
ba180fd4 | 173 | if (!nested) |
c14b8494 | 174 | pending = from_irq_stack(nested); |
ba180fd4 | 175 | } while (pending); |
c14b8494 JD |
176 | } |
177 | ||
00361683 | 178 | void set_handler(int sig) |
0805d89c GS |
179 | { |
180 | struct sigaction action; | |
e87df986 | 181 | int flags = SA_SIGINFO | SA_ONSTACK; |
1d7173ba | 182 | sigset_t sig_mask; |
0805d89c | 183 | |
7eb12255 | 184 | action.sa_sigaction = hard_handler; |
4b84c69b | 185 | |
e87df986 | 186 | /* block irq ones */ |
0805d89c | 187 | sigemptyset(&action.sa_mask); |
e87df986 AV |
188 | sigaddset(&action.sa_mask, SIGVTALRM); |
189 | sigaddset(&action.sa_mask, SIGIO); | |
190 | sigaddset(&action.sa_mask, SIGWINCH); | |
4b84c69b | 191 | |
e6a2d1f7 JD |
192 | if (sig == SIGSEGV) |
193 | flags |= SA_NODEFER; | |
194 | ||
e87df986 AV |
195 | if (sigismember(&action.sa_mask, sig)) |
196 | flags |= SA_RESTART; /* if it's an irq signal */ | |
197 | ||
198 | action.sa_flags = flags; | |
0805d89c | 199 | action.sa_restorer = NULL; |
ba180fd4 | 200 | if (sigaction(sig, &action, NULL) < 0) |
1d7173ba JD |
201 | panic("sigaction failed - errno = %d\n", errno); |
202 | ||
203 | sigemptyset(&sig_mask); | |
204 | sigaddset(&sig_mask, sig); | |
ba180fd4 | 205 | if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) |
1d7173ba | 206 | panic("sigprocmask failed - errno = %d\n", errno); |
0805d89c GS |
207 | } |
208 | ||
209 | int change_sig(int signal, int on) | |
210 | { | |
cfef8f34 | 211 | sigset_t sigset; |
0805d89c GS |
212 | |
213 | sigemptyset(&sigset); | |
214 | sigaddset(&sigset, signal); | |
cfef8f34 | 215 | if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) |
c9a3072d | 216 | return -errno; |
cfef8f34 JD |
217 | |
218 | return 0; | |
0805d89c GS |
219 | } |
220 | ||
0805d89c GS |
221 | void block_signals(void) |
222 | { | |
1d7173ba | 223 | signals_enabled = 0; |
ba180fd4 JD |
224 | /* |
225 | * This must return with signals disabled, so this barrier | |
53b17332 JD |
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 | */ | |
fce8c41c | 230 | barrier(); |
0805d89c GS |
231 | } |
232 | ||
233 | void unblock_signals(void) | |
234 | { | |
1d7173ba | 235 | int save_pending; |
0805d89c | 236 | |
ba180fd4 | 237 | if (signals_enabled == 1) |
1d7173ba | 238 | return; |
0805d89c | 239 | |
ba180fd4 JD |
240 | /* |
241 | * We loop because the IRQ handler returns with interrupts off. So, | |
1d7173ba | 242 | * interrupts may have arrived and we need to re-enable them and |
cfef8f34 | 243 | * recheck signals_pending. |
1d7173ba | 244 | */ |
5134d8fe | 245 | while (1) { |
ba180fd4 JD |
246 | /* |
247 | * Save and reset save_pending after enabling signals. This | |
cfef8f34 | 248 | * way, signals_pending won't be changed while we're reading it. |
1d7173ba JD |
249 | */ |
250 | signals_enabled = 1; | |
251 | ||
ba180fd4 | 252 | /* |
cfef8f34 | 253 | * Setting signals_enabled and reading signals_pending must |
53b17332 JD |
254 | * happen in this order. |
255 | */ | |
fce8c41c | 256 | barrier(); |
53b17332 | 257 | |
cfef8f34 | 258 | save_pending = signals_pending; |
fce8c41c | 259 | if (save_pending == 0) |
1d7173ba JD |
260 | return; |
261 | ||
cfef8f34 | 262 | signals_pending = 0; |
1d7173ba | 263 | |
ba180fd4 JD |
264 | /* |
265 | * We have pending interrupts, so disable signals, as the | |
1d7173ba JD |
266 | * handlers expect them off when they are called. They will |
267 | * be enabled again above. | |
268 | */ | |
269 | ||
270 | signals_enabled = 0; | |
271 | ||
ba180fd4 JD |
272 | /* |
273 | * Deal with SIGIO first because the alarm handler might | |
1d7173ba JD |
274 | * schedule, leaving the pending SIGIO stranded until we come |
275 | * back here. | |
276 | */ | |
ba180fd4 | 277 | if (save_pending & SIGIO_MASK) |
e6a2d1f7 | 278 | sig_handler_common(SIGIO, NULL); |
1d7173ba | 279 | |
ba180fd4 | 280 | if (save_pending & SIGVTALRM_MASK) |
61b63c55 | 281 | real_alarm_handler(NULL); |
1d7173ba | 282 | } |
0805d89c GS |
283 | } |
284 | ||
285 | int get_signals(void) | |
286 | { | |
1d7173ba | 287 | return signals_enabled; |
0805d89c GS |
288 | } |
289 | ||
290 | int set_signals(int enable) | |
291 | { | |
0805d89c | 292 | int ret; |
ba180fd4 | 293 | if (signals_enabled == enable) |
1d7173ba | 294 | return enable; |
0805d89c | 295 | |
1d7173ba | 296 | ret = signals_enabled; |
ba180fd4 | 297 | if (enable) |
1d7173ba JD |
298 | unblock_signals(); |
299 | else block_signals(); | |
0805d89c | 300 | |
1d7173ba | 301 | return ret; |
0805d89c | 302 | } |