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
14 #include <as-layout.h>
15 #include <kern_util.h>
17 #include <sysdep/mcontext.h>
19 void (*sig_info[NSIG])(int, struct siginfo *, 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 [SIGALRM] = timer_handler
30 static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
33 int save_errno = errno;
37 /* For segfaults, we want the data from the sigcontext. */
38 get_regs_from_mc(&r, mc);
39 GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
42 /* enable signals if sig isn't IRQ signal */
43 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
46 (*sig_info[sig])(sig, si, &r);
52 * These are the asynchronous signals. SIGPROF is excluded because we want to
53 * be able to profile all of UML, not just the non-critical sections. If
54 * profiling is not thread-safe, then that is not my problem. We can disable
55 * profiling when SMP is enabled in that case.
58 #define SIGIO_MASK (1 << SIGIO_BIT)
61 #define SIGALRM_MASK (1 << SIGALRM_BIT)
63 static int signals_enabled;
64 static unsigned int signals_pending;
65 static unsigned int signals_active = 0;
67 void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
71 enabled = signals_enabled;
72 if (!enabled && (sig == SIGIO)) {
73 signals_pending |= SIGIO_MASK;
79 sig_handler_common(sig, si, mc);
84 static void timer_real_alarm_handler(mcontext_t *mc)
86 struct uml_pt_regs regs;
89 get_regs_from_mc(®s, mc);
90 timer_handler(SIGALRM, NULL, ®s);
93 void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
97 enabled = signals_enabled;
98 if (!signals_enabled) {
99 signals_pending |= SIGALRM_MASK;
105 signals_active |= SIGALRM_MASK;
107 timer_real_alarm_handler(mc);
109 signals_active &= ~SIGALRM_MASK;
111 set_signals(enabled);
114 void deliver_alarm(void) {
115 timer_alarm_handler(SIGALRM, NULL, NULL);
118 void timer_set_signal_handler(void)
120 set_handler(SIGALRM);
123 void set_sigstack(void *sig_stack, int size)
128 .ss_size = size - sizeof(void *)
131 if (sigaltstack(&stack, NULL) != 0)
132 panic("enabling signal stack failed, errno = %d\n", errno);
135 static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
136 [SIGSEGV] = sig_handler,
137 [SIGBUS] = sig_handler,
138 [SIGILL] = sig_handler,
139 [SIGFPE] = sig_handler,
140 [SIGTRAP] = sig_handler,
142 [SIGIO] = sig_handler,
143 [SIGWINCH] = sig_handler,
144 [SIGALRM] = timer_alarm_handler
147 static void hard_handler(int sig, siginfo_t *si, void *p)
149 struct ucontext *uc = p;
150 mcontext_t *mc = &uc->uc_mcontext;
151 unsigned long pending = 1UL << sig;
157 * pending comes back with one bit set for each
158 * interrupt that arrived while setting up the stack,
159 * plus a bit for this interrupt, plus the zero bit is
160 * set if this is a nested interrupt.
161 * If bail is true, then we interrupted another
162 * handler setting up the stack. In this case, we
163 * have to return, and the upper handler will deal
164 * with this interrupt.
166 bail = to_irq_stack(&pending);
170 nested = pending & 1;
173 while ((sig = ffs(pending)) != 0){
175 pending &= ~(1 << sig);
176 (*handlers[sig])(sig, (struct siginfo *)si, mc);
180 * Again, pending comes back with a mask of signals
181 * that arrived while tearing down the stack. If this
182 * is non-zero, we just go back, set up the stack
183 * again, and handle the new interrupts.
186 pending = from_irq_stack(nested);
190 void set_handler(int sig)
192 struct sigaction action;
193 int flags = SA_SIGINFO | SA_ONSTACK;
196 action.sa_sigaction = hard_handler;
199 sigemptyset(&action.sa_mask);
200 sigaddset(&action.sa_mask, SIGIO);
201 sigaddset(&action.sa_mask, SIGWINCH);
202 sigaddset(&action.sa_mask, SIGALRM);
207 if (sigismember(&action.sa_mask, sig))
208 flags |= SA_RESTART; /* if it's an irq signal */
210 action.sa_flags = flags;
211 action.sa_restorer = NULL;
212 if (sigaction(sig, &action, NULL) < 0)
213 panic("sigaction failed - errno = %d\n", errno);
215 sigemptyset(&sig_mask);
216 sigaddset(&sig_mask, sig);
217 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
218 panic("sigprocmask failed - errno = %d\n", errno);
221 int change_sig(int signal, int on)
225 sigemptyset(&sigset);
226 sigaddset(&sigset, signal);
227 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
233 void block_signals(void)
237 * This must return with signals disabled, so this barrier
238 * ensures that writes are flushed out before the return.
239 * This might matter if gcc figures out how to inline this and
240 * decides to shuffle this code into the caller.
245 void unblock_signals(void)
249 if (signals_enabled == 1)
253 * We loop because the IRQ handler returns with interrupts off. So,
254 * interrupts may have arrived and we need to re-enable them and
255 * recheck signals_pending.
259 * Save and reset save_pending after enabling signals. This
260 * way, signals_pending won't be changed while we're reading it.
265 * Setting signals_enabled and reading signals_pending must
266 * happen in this order.
270 save_pending = signals_pending;
271 if (save_pending == 0)
277 * We have pending interrupts, so disable signals, as the
278 * handlers expect them off when they are called. They will
279 * be enabled again above.
285 * Deal with SIGIO first because the alarm handler might
286 * schedule, leaving the pending SIGIO stranded until we come
289 * SIGIO's handler doesn't use siginfo or mcontext,
290 * so they can be NULL.
292 if (save_pending & SIGIO_MASK)
293 sig_handler_common(SIGIO, NULL, NULL);
295 /* Do not reenter the handler */
297 if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
298 timer_real_alarm_handler(NULL);
300 /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
302 if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
308 int get_signals(void)
310 return signals_enabled;
313 int set_signals(int enable)
316 if (signals_enabled == enable)
319 ret = signals_enabled;
322 else block_signals();
327 int os_is_signal_stack(void)
330 sigaltstack(NULL, &ss);
332 return ss.ss_flags & SS_ONSTACK;