2 * Copyright (C) 2004 PathScale, Inc
3 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
13 #include "sysdep/barrier.h"
14 #include "sysdep/sigcontext.h"
18 * These are the asynchronous signals. SIGVTALRM and SIGARLM are handled
19 * together under SIGVTALRM_BIT. SIGPROF is excluded because we want to
20 * be able to profile all of UML, not just the non-critical sections. If
21 * profiling is not thread-safe, then that is not my problem. We can disable
22 * profiling when SMP is enabled in that case.
25 #define SIGIO_MASK (1 << SIGIO_BIT)
27 #define SIGVTALRM_BIT 1
28 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
31 #define SIGALRM_MASK (1 << SIGALRM_BIT)
34 * These are used by both the signal handlers and
35 * block/unblock_signals. I don't want modifications cached in a
36 * register - they must go straight to memory.
38 static volatile int signals_enabled = 1;
39 static volatile int pending = 0;
41 void sig_handler(int sig, struct sigcontext *sc)
45 enabled = signals_enabled;
46 if (!enabled && (sig == SIGIO)) {
47 pending |= SIGIO_MASK;
53 sig_handler_common_skas(sig, sc);
58 static void real_alarm_handler(int sig, struct sigcontext *sc)
60 struct uml_pt_regs regs;
69 timer_handler(sig, ®s);
75 void alarm_handler(int sig, struct sigcontext *sc)
79 enabled = signals_enabled;
80 if (!signals_enabled) {
82 pending |= SIGVTALRM_MASK;
83 else pending |= SIGALRM_MASK;
90 real_alarm_handler(sig, sc);
94 void set_sigstack(void *sig_stack, int size)
96 stack_t stack = ((stack_t) { .ss_flags = 0,
97 .ss_sp = (__ptr_t) sig_stack,
98 .ss_size = size - sizeof(void *) });
100 if (sigaltstack(&stack, NULL) != 0)
101 panic("enabling signal stack failed, errno = %d\n", errno);
104 void remove_sigstack(void)
106 stack_t stack = ((stack_t) { .ss_flags = SS_DISABLE,
110 if (sigaltstack(&stack, NULL) != 0)
111 panic("disabling signal stack failed, errno = %d\n", errno);
114 void (*handlers[_NSIG])(int sig, struct sigcontext *sc);
116 void handle_signal(int sig, struct sigcontext *sc)
118 unsigned long pending = 1UL << sig;
124 * pending comes back with one bit set for each
125 * interrupt that arrived while setting up the stack,
126 * plus a bit for this interrupt, plus the zero bit is
127 * set if this is a nested interrupt.
128 * If bail is true, then we interrupted another
129 * handler setting up the stack. In this case, we
130 * have to return, and the upper handler will deal
131 * with this interrupt.
133 bail = to_irq_stack(&pending);
137 nested = pending & 1;
140 while ((sig = ffs(pending)) != 0){
142 pending &= ~(1 << sig);
143 (*handlers[sig])(sig, sc);
147 * Again, pending comes back with a mask of signals
148 * that arrived while tearing down the stack. If this
149 * is non-zero, we just go back, set up the stack
150 * again, and handle the new interrupts.
153 pending = from_irq_stack(nested);
157 extern void hard_handler(int sig);
159 void set_handler(int sig, void (*handler)(int), int flags, ...)
161 struct sigaction action;
166 handlers[sig] = (void (*)(int, struct sigcontext *)) handler;
167 action.sa_handler = hard_handler;
169 sigemptyset(&action.sa_mask);
172 while ((mask = va_arg(ap, int)) != -1)
173 sigaddset(&action.sa_mask, mask);
176 action.sa_flags = flags;
177 action.sa_restorer = NULL;
178 if (sigaction(sig, &action, NULL) < 0)
179 panic("sigaction failed - errno = %d\n", errno);
181 sigemptyset(&sig_mask);
182 sigaddset(&sig_mask, sig);
183 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
184 panic("sigprocmask failed - errno = %d\n", errno);
187 int change_sig(int signal, int on)
189 sigset_t sigset, old;
191 sigemptyset(&sigset);
192 sigaddset(&sigset, signal);
193 sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
194 return !sigismember(&old, signal);
197 void block_signals(void)
201 * This must return with signals disabled, so this barrier
202 * ensures that writes are flushed out before the return.
203 * This might matter if gcc figures out how to inline this and
204 * decides to shuffle this code into the caller.
209 void unblock_signals(void)
213 if (signals_enabled == 1)
217 * We loop because the IRQ handler returns with interrupts off. So,
218 * interrupts may have arrived and we need to re-enable them and
223 * Save and reset save_pending after enabling signals. This
224 * way, pending won't be changed while we're reading it.
229 * Setting signals_enabled and reading pending must
230 * happen in this order.
234 save_pending = pending;
235 if (save_pending == 0) {
237 * This must return with signals enabled, so
238 * this barrier ensures that writes are
239 * flushed out before the return. This might
240 * matter if gcc figures out how to inline
241 * this (unlikely, given its size) and decides
242 * to shuffle this code into the caller.
251 * We have pending interrupts, so disable signals, as the
252 * handlers expect them off when they are called. They will
253 * be enabled again above.
259 * Deal with SIGIO first because the alarm handler might
260 * schedule, leaving the pending SIGIO stranded until we come
263 if (save_pending & SIGIO_MASK)
264 sig_handler_common_skas(SIGIO, NULL);
266 if (save_pending & SIGALRM_MASK)
267 real_alarm_handler(SIGALRM, NULL);
269 if (save_pending & SIGVTALRM_MASK)
270 real_alarm_handler(SIGVTALRM, NULL);
274 int get_signals(void)
276 return signals_enabled;
279 int set_signals(int enable)
282 if (signals_enabled == enable)
285 ret = signals_enabled;
288 else block_signals();