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"
15 #include "sysdep/mcontext.h"
17 void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
18 [SIGTRAP] = relay_signal,
19 [SIGFPE] = relay_signal,
20 [SIGILL] = relay_signal,
22 [SIGBUS] = bus_handler,
23 [SIGSEGV] = segv_handler,
24 [SIGIO] = sigio_handler,
25 [SIGVTALRM] = timer_handler };
27 static void sig_handler_common(int sig, mcontext_t *mc)
30 int save_errno = errno;
34 /* For segfaults, we want the data from the sigcontext. */
35 get_regs_from_mc(&r, mc);
36 GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
39 /* enable signals if sig isn't IRQ signal */
40 if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
43 (*sig_info[sig])(sig, &r);
49 * These are the asynchronous signals. SIGPROF is excluded because we want to
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.
55 #define SIGIO_MASK (1 << SIGIO_BIT)
57 #define SIGVTALRM_BIT 1
58 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
60 static int signals_enabled;
61 static unsigned int signals_pending;
63 void sig_handler(int sig, mcontext_t *mc)
67 enabled = signals_enabled;
68 if (!enabled && (sig == SIGIO)) {
69 signals_pending |= SIGIO_MASK;
75 sig_handler_common(sig, mc);
80 static void real_alarm_handler(mcontext_t *mc)
82 struct uml_pt_regs regs;
85 get_regs_from_mc(®s, mc);
88 timer_handler(SIGVTALRM, ®s);
91 void alarm_handler(int sig, mcontext_t *mc)
95 enabled = signals_enabled;
96 if (!signals_enabled) {
97 signals_pending |= SIGVTALRM_MASK;
103 real_alarm_handler(mc);
104 set_signals(enabled);
107 void timer_init(void)
109 set_handler(SIGVTALRM);
112 void set_sigstack(void *sig_stack, int size)
114 stack_t stack = ((stack_t) { .ss_flags = 0,
115 .ss_sp = (__ptr_t) sig_stack,
116 .ss_size = size - sizeof(void *) });
118 if (sigaltstack(&stack, NULL) != 0)
119 panic("enabling signal stack failed, errno = %d\n", errno);
122 static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = {
123 [SIGSEGV] = sig_handler,
124 [SIGBUS] = sig_handler,
125 [SIGILL] = sig_handler,
126 [SIGFPE] = sig_handler,
127 [SIGTRAP] = sig_handler,
129 [SIGIO] = sig_handler,
130 [SIGWINCH] = sig_handler,
131 [SIGVTALRM] = alarm_handler
135 static void hard_handler(int sig, siginfo_t *info, void *p)
137 struct ucontext *uc = p;
138 mcontext_t *mc = &uc->uc_mcontext;
139 unsigned long pending = 1UL << sig;
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.
154 bail = to_irq_stack(&pending);
158 nested = pending & 1;
161 while ((sig = ffs(pending)) != 0){
163 pending &= ~(1 << sig);
164 (*handlers[sig])(sig, mc);
168 * Again, pending comes back with a mask of signals
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.
174 pending = from_irq_stack(nested);
178 void set_handler(int sig)
180 struct sigaction action;
181 int flags = SA_SIGINFO | SA_ONSTACK;
184 action.sa_sigaction = hard_handler;
187 sigemptyset(&action.sa_mask);
188 sigaddset(&action.sa_mask, SIGVTALRM);
189 sigaddset(&action.sa_mask, SIGIO);
190 sigaddset(&action.sa_mask, SIGWINCH);
195 if (sigismember(&action.sa_mask, sig))
196 flags |= SA_RESTART; /* if it's an irq signal */
198 action.sa_flags = flags;
199 action.sa_restorer = NULL;
200 if (sigaction(sig, &action, NULL) < 0)
201 panic("sigaction failed - errno = %d\n", errno);
203 sigemptyset(&sig_mask);
204 sigaddset(&sig_mask, sig);
205 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
206 panic("sigprocmask failed - errno = %d\n", errno);
209 int change_sig(int signal, int on)
213 sigemptyset(&sigset);
214 sigaddset(&sigset, signal);
215 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
221 void block_signals(void)
225 * This must return with signals disabled, so this barrier
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.
233 void unblock_signals(void)
237 if (signals_enabled == 1)
241 * We loop because the IRQ handler returns with interrupts off. So,
242 * interrupts may have arrived and we need to re-enable them and
243 * recheck signals_pending.
247 * Save and reset save_pending after enabling signals. This
248 * way, signals_pending won't be changed while we're reading it.
253 * Setting signals_enabled and reading signals_pending must
254 * happen in this order.
258 save_pending = signals_pending;
259 if (save_pending == 0)
265 * We have pending interrupts, so disable signals, as the
266 * handlers expect them off when they are called. They will
267 * be enabled again above.
273 * Deal with SIGIO first because the alarm handler might
274 * schedule, leaving the pending SIGIO stranded until we come
277 if (save_pending & SIGIO_MASK)
278 sig_handler_common(SIGIO, NULL);
280 if (save_pending & SIGVTALRM_MASK)
281 real_alarm_handler(NULL);
285 int get_signals(void)
287 return signals_enabled;
290 int set_signals(int enable)
293 if (signals_enabled == enable)
296 ret = signals_enabled;
299 else block_signals();