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 <sys/ucontext.h>
18 #include <sysdep/mcontext.h>
19 #include <um_malloc.h>
21 void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
22 [SIGTRAP] = relay_signal,
23 [SIGFPE] = relay_signal,
24 [SIGILL] = relay_signal,
26 [SIGBUS] = bus_handler,
27 [SIGSEGV] = segv_handler,
28 [SIGIO] = sigio_handler,
29 [SIGALRM] = timer_handler
32 static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
35 int save_errno = errno;
39 /* For segfaults, we want the data from the sigcontext. */
40 get_regs_from_mc(&r, mc);
41 GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
44 /* enable signals if sig isn't IRQ signal */
45 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
48 (*sig_info[sig])(sig, si, &r);
54 * These are the asynchronous signals. SIGPROF is excluded because we want to
55 * be able to profile all of UML, not just the non-critical sections. If
56 * profiling is not thread-safe, then that is not my problem. We can disable
57 * profiling when SMP is enabled in that case.
60 #define SIGIO_MASK (1 << SIGIO_BIT)
63 #define SIGALRM_MASK (1 << SIGALRM_BIT)
65 static int signals_enabled;
66 static unsigned int signals_pending;
68 void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
72 enabled = signals_enabled;
73 if (!enabled && (sig == SIGIO)) {
74 signals_pending |= SIGIO_MASK;
80 sig_handler_common(sig, si, mc);
85 static void timer_real_alarm_handler(mcontext_t *mc)
87 struct uml_pt_regs regs;
90 get_regs_from_mc(®s, mc);
91 timer_handler(SIGALRM, NULL, ®s);
94 void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
98 enabled = signals_enabled;
99 if (!signals_enabled) {
100 signals_pending |= SIGALRM_MASK;
106 timer_real_alarm_handler(mc);
107 set_signals(enabled);
110 void deliver_alarm(void) {
111 timer_alarm_handler(SIGALRM, NULL, NULL);
114 void timer_set_signal_handler(void)
116 set_handler(SIGALRM);
119 void set_sigstack(void *sig_stack, int size)
124 .ss_size = size - sizeof(void *)
127 if (sigaltstack(&stack, NULL) != 0)
128 panic("enabling signal stack failed, errno = %d\n", errno);
131 static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
132 [SIGSEGV] = sig_handler,
133 [SIGBUS] = sig_handler,
134 [SIGILL] = sig_handler,
135 [SIGFPE] = sig_handler,
136 [SIGTRAP] = sig_handler,
138 [SIGIO] = sig_handler,
139 [SIGWINCH] = sig_handler,
140 [SIGALRM] = timer_alarm_handler
143 static void hard_handler(int sig, siginfo_t *si, void *p)
146 mcontext_t *mc = &uc->uc_mcontext;
147 unsigned long pending = 1UL << sig;
153 * pending comes back with one bit set for each
154 * interrupt that arrived while setting up the stack,
155 * plus a bit for this interrupt, plus the zero bit is
156 * set if this is a nested interrupt.
157 * If bail is true, then we interrupted another
158 * handler setting up the stack. In this case, we
159 * have to return, and the upper handler will deal
160 * with this interrupt.
162 bail = to_irq_stack(&pending);
166 nested = pending & 1;
169 while ((sig = ffs(pending)) != 0){
171 pending &= ~(1 << sig);
172 (*handlers[sig])(sig, (struct siginfo *)si, mc);
176 * Again, pending comes back with a mask of signals
177 * that arrived while tearing down the stack. If this
178 * is non-zero, we just go back, set up the stack
179 * again, and handle the new interrupts.
182 pending = from_irq_stack(nested);
186 void set_handler(int sig)
188 struct sigaction action;
189 int flags = SA_SIGINFO | SA_ONSTACK;
192 action.sa_sigaction = hard_handler;
195 sigemptyset(&action.sa_mask);
196 sigaddset(&action.sa_mask, SIGIO);
197 sigaddset(&action.sa_mask, SIGWINCH);
198 sigaddset(&action.sa_mask, SIGALRM);
203 if (sigismember(&action.sa_mask, sig))
204 flags |= SA_RESTART; /* if it's an irq signal */
206 action.sa_flags = flags;
207 action.sa_restorer = NULL;
208 if (sigaction(sig, &action, NULL) < 0)
209 panic("sigaction failed - errno = %d\n", errno);
211 sigemptyset(&sig_mask);
212 sigaddset(&sig_mask, sig);
213 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
214 panic("sigprocmask failed - errno = %d\n", errno);
217 int change_sig(int signal, int on)
221 sigemptyset(&sigset);
222 sigaddset(&sigset, signal);
223 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
229 void block_signals(void)
233 * This must return with signals disabled, so this barrier
234 * ensures that writes are flushed out before the return.
235 * This might matter if gcc figures out how to inline this and
236 * decides to shuffle this code into the caller.
241 void unblock_signals(void)
245 if (signals_enabled == 1)
249 * We loop because the IRQ handler returns with interrupts off. So,
250 * interrupts may have arrived and we need to re-enable them and
251 * recheck signals_pending.
255 * Save and reset save_pending after enabling signals. This
256 * way, signals_pending won't be changed while we're reading it.
261 * Setting signals_enabled and reading signals_pending must
262 * happen in this order.
266 save_pending = signals_pending;
267 if (save_pending == 0)
273 * We have pending interrupts, so disable signals, as the
274 * handlers expect them off when they are called. They will
275 * be enabled again above.
281 * Deal with SIGIO first because the alarm handler might
282 * schedule, leaving the pending SIGIO stranded until we come
285 * SIGIO's handler doesn't use siginfo or mcontext,
286 * so they can be NULL.
288 if (save_pending & SIGIO_MASK)
289 sig_handler_common(SIGIO, NULL, NULL);
291 if (save_pending & SIGALRM_MASK)
292 timer_real_alarm_handler(NULL);
296 int get_signals(void)
298 return signals_enabled;
301 int set_signals(int enable)
304 if (signals_enabled == enable)
307 ret = signals_enabled;
310 else block_signals();
315 int os_is_signal_stack(void)
318 sigaltstack(NULL, &ss);
320 return ss.ss_flags & SS_ONSTACK;