2 * Copyright (C) 2004 PathScale, Inc
3 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
12 #include "as-layout.h"
13 #include "kern_util.h"
16 #include "sysdep/barrier.h"
17 #include "sysdep/sigcontext.h"
19 void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
20 [SIGTRAP] = relay_signal,
21 [SIGFPE] = relay_signal,
22 [SIGILL] = relay_signal,
24 [SIGBUS] = bus_handler,
25 [SIGSEGV] = segv_handler,
26 [SIGIO] = sigio_handler,
27 [SIGVTALRM] = timer_handler };
29 static void sig_handler_common(int sig, struct sigcontext *sc)
32 int save_errno = errno;
36 /* For segfaults, we want the data from the sigcontext. */
38 GET_FAULTINFO_FROM_SC(r.faultinfo, sc);
41 /* enable signals if sig isn't IRQ signal */
42 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
45 (*sig_info[sig])(sig, &r);
51 * These are the asynchronous signals. SIGPROF is excluded because we want to
52 * be able to profile all of UML, not just the non-critical sections. If
53 * profiling is not thread-safe, then that is not my problem. We can disable
54 * profiling when SMP is enabled in that case.
57 #define SIGIO_MASK (1 << SIGIO_BIT)
59 #define SIGVTALRM_BIT 1
60 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
62 static int signals_enabled;
63 static unsigned int signals_pending;
65 void sig_handler(int sig, struct sigcontext *sc)
69 enabled = signals_enabled;
70 if (!enabled && (sig == SIGIO)) {
71 signals_pending |= SIGIO_MASK;
77 sig_handler_common(sig, sc);
82 static void real_alarm_handler(struct sigcontext *sc)
84 struct uml_pt_regs regs;
90 timer_handler(SIGVTALRM, ®s);
93 void alarm_handler(int sig, struct sigcontext *sc)
97 enabled = signals_enabled;
98 if (!signals_enabled) {
99 signals_pending |= SIGVTALRM_MASK;
105 real_alarm_handler(sc);
106 set_signals(enabled);
109 void timer_init(void)
111 set_handler(SIGVTALRM);
114 void set_sigstack(void *sig_stack, int size)
116 stack_t stack = ((stack_t) { .ss_flags = 0,
117 .ss_sp = (__ptr_t) sig_stack,
118 .ss_size = size - sizeof(void *) });
120 if (sigaltstack(&stack, NULL) != 0)
121 panic("enabling signal stack failed, errno = %d\n", errno);
124 static void (*handlers[_NSIG])(int sig, struct sigcontext *sc) = {
125 [SIGSEGV] = sig_handler,
126 [SIGBUS] = sig_handler,
127 [SIGILL] = sig_handler,
128 [SIGFPE] = sig_handler,
129 [SIGTRAP] = sig_handler,
131 [SIGIO] = sig_handler,
132 [SIGWINCH] = sig_handler,
133 [SIGVTALRM] = alarm_handler
136 static void handle_signal(int sig, struct sigcontext *sc)
138 unsigned long pending = 1UL << sig;
144 * pending comes back with one bit set for each
145 * interrupt that arrived while setting up the stack,
146 * plus a bit for this interrupt, plus the zero bit is
147 * set if this is a nested interrupt.
148 * If bail is true, then we interrupted another
149 * handler setting up the stack. In this case, we
150 * have to return, and the upper handler will deal
151 * with this interrupt.
153 bail = to_irq_stack(&pending);
157 nested = pending & 1;
160 while ((sig = ffs(pending)) != 0){
162 pending &= ~(1 << sig);
163 (*handlers[sig])(sig, sc);
167 * Again, pending comes back with a mask of signals
168 * that arrived while tearing down the stack. If this
169 * is non-zero, we just go back, set up the stack
170 * again, and handle the new interrupts.
173 pending = from_irq_stack(nested);
177 static void hard_handler(int sig, siginfo_t *info, void *p)
179 struct ucontext *uc = p;
180 handle_signal(sig, (struct sigcontext *) &uc->uc_mcontext);
183 void set_handler(int sig)
185 struct sigaction action;
186 int flags = SA_SIGINFO | SA_ONSTACK;
189 action.sa_sigaction = hard_handler;
192 sigemptyset(&action.sa_mask);
193 sigaddset(&action.sa_mask, SIGVTALRM);
194 sigaddset(&action.sa_mask, SIGIO);
195 sigaddset(&action.sa_mask, SIGWINCH);
200 if (sigismember(&action.sa_mask, sig))
201 flags |= SA_RESTART; /* if it's an irq signal */
203 action.sa_flags = flags;
204 action.sa_restorer = NULL;
205 if (sigaction(sig, &action, NULL) < 0)
206 panic("sigaction failed - errno = %d\n", errno);
208 sigemptyset(&sig_mask);
209 sigaddset(&sig_mask, sig);
210 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
211 panic("sigprocmask failed - errno = %d\n", errno);
214 int change_sig(int signal, int on)
218 sigemptyset(&sigset);
219 sigaddset(&sigset, signal);
220 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
226 void block_signals(void)
230 * This must return with signals disabled, so this barrier
231 * ensures that writes are flushed out before the return.
232 * This might matter if gcc figures out how to inline this and
233 * decides to shuffle this code into the caller.
238 void unblock_signals(void)
242 if (signals_enabled == 1)
246 * We loop because the IRQ handler returns with interrupts off. So,
247 * interrupts may have arrived and we need to re-enable them and
248 * recheck signals_pending.
252 * Save and reset save_pending after enabling signals. This
253 * way, signals_pending won't be changed while we're reading it.
258 * Setting signals_enabled and reading signals_pending must
259 * happen in this order.
263 save_pending = signals_pending;
264 if (save_pending == 0)
270 * We have pending interrupts, so disable signals, as the
271 * handlers expect them off when they are called. They will
272 * be enabled again above.
278 * Deal with SIGIO first because the alarm handler might
279 * schedule, leaving the pending SIGIO stranded until we come
282 if (save_pending & SIGIO_MASK)
283 sig_handler_common(SIGIO, NULL);
285 if (save_pending & SIGVTALRM_MASK)
286 real_alarm_handler(NULL);
290 int get_signals(void)
292 return signals_enabled;
295 int set_signals(int enable)
298 if (signals_enabled == enable)
301 ret = signals_enabled;
304 else block_signals();