1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
4 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
5 * Copyright (C) 2004 PathScale, Inc
6 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
15 #include <as-layout.h>
16 #include <kern_util.h>
18 #include <sysdep/mcontext.h>
19 #include <um_malloc.h>
20 #include <sys/ucontext.h>
22 void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
23 [SIGTRAP] = relay_signal,
24 [SIGFPE] = relay_signal,
25 [SIGILL] = relay_signal,
27 [SIGBUS] = bus_handler,
28 [SIGSEGV] = segv_handler,
29 [SIGIO] = sigio_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))
46 unblock_signals_trace();
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;
67 static unsigned int signals_active = 0;
69 void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
73 enabled = signals_enabled;
74 if (!enabled && (sig == SIGIO)) {
75 signals_pending |= SIGIO_MASK;
79 block_signals_trace();
81 sig_handler_common(sig, si, mc);
83 set_signals_trace(enabled);
86 static void timer_real_alarm_handler(mcontext_t *mc)
88 struct uml_pt_regs regs;
91 get_regs_from_mc(®s, mc);
93 memset(®s, 0, sizeof(regs));
94 timer_handler(SIGALRM, NULL, ®s);
97 void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
101 enabled = signals_enabled;
102 if (!signals_enabled) {
103 signals_pending |= SIGALRM_MASK;
107 block_signals_trace();
109 signals_active |= SIGALRM_MASK;
111 timer_real_alarm_handler(mc);
113 signals_active &= ~SIGALRM_MASK;
115 set_signals_trace(enabled);
118 void deliver_alarm(void) {
119 timer_alarm_handler(SIGALRM, NULL, NULL);
122 void timer_set_signal_handler(void)
124 set_handler(SIGALRM);
127 void set_sigstack(void *sig_stack, int size)
132 .ss_size = size - sizeof(void *)
135 if (sigaltstack(&stack, NULL) != 0)
136 panic("enabling signal stack failed, errno = %d\n", errno);
139 static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
144 void register_pm_wake_signal(void)
146 set_handler(SIGUSR1);
149 static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
150 [SIGSEGV] = sig_handler,
151 [SIGBUS] = sig_handler,
152 [SIGILL] = sig_handler,
153 [SIGFPE] = sig_handler,
154 [SIGTRAP] = sig_handler,
156 [SIGIO] = sig_handler,
157 [SIGWINCH] = sig_handler,
158 [SIGALRM] = timer_alarm_handler,
160 [SIGUSR1] = sigusr1_handler,
163 static void hard_handler(int sig, siginfo_t *si, void *p)
166 mcontext_t *mc = &uc->uc_mcontext;
167 unsigned long pending = 1UL << sig;
173 * pending comes back with one bit set for each
174 * interrupt that arrived while setting up the stack,
175 * plus a bit for this interrupt, plus the zero bit is
176 * set if this is a nested interrupt.
177 * If bail is true, then we interrupted another
178 * handler setting up the stack. In this case, we
179 * have to return, and the upper handler will deal
180 * with this interrupt.
182 bail = to_irq_stack(&pending);
186 nested = pending & 1;
189 while ((sig = ffs(pending)) != 0){
191 pending &= ~(1 << sig);
192 (*handlers[sig])(sig, (struct siginfo *)si, mc);
196 * Again, pending comes back with a mask of signals
197 * that arrived while tearing down the stack. If this
198 * is non-zero, we just go back, set up the stack
199 * again, and handle the new interrupts.
202 pending = from_irq_stack(nested);
206 void set_handler(int sig)
208 struct sigaction action;
209 int flags = SA_SIGINFO | SA_ONSTACK;
212 action.sa_sigaction = hard_handler;
215 sigemptyset(&action.sa_mask);
216 sigaddset(&action.sa_mask, SIGIO);
217 sigaddset(&action.sa_mask, SIGWINCH);
218 sigaddset(&action.sa_mask, SIGALRM);
223 if (sigismember(&action.sa_mask, sig))
224 flags |= SA_RESTART; /* if it's an irq signal */
226 action.sa_flags = flags;
227 action.sa_restorer = NULL;
228 if (sigaction(sig, &action, NULL) < 0)
229 panic("sigaction failed - errno = %d\n", errno);
231 sigemptyset(&sig_mask);
232 sigaddset(&sig_mask, sig);
233 if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
234 panic("sigprocmask failed - errno = %d\n", errno);
237 int change_sig(int signal, int on)
241 sigemptyset(&sigset);
242 sigaddset(&sigset, signal);
243 if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
249 void block_signals(void)
253 * This must return with signals disabled, so this barrier
254 * ensures that writes are flushed out before the return.
255 * This might matter if gcc figures out how to inline this and
256 * decides to shuffle this code into the caller.
261 void unblock_signals(void)
265 if (signals_enabled == 1)
271 * We loop because the IRQ handler returns with interrupts off. So,
272 * interrupts may have arrived and we need to re-enable them and
273 * recheck signals_pending.
277 * Save and reset save_pending after enabling signals. This
278 * way, signals_pending won't be changed while we're reading it.
280 * Setting signals_enabled and reading signals_pending must
281 * happen in this order, so have the barrier here.
285 save_pending = signals_pending;
286 if (save_pending == 0)
292 * We have pending interrupts, so disable signals, as the
293 * handlers expect them off when they are called. They will
294 * be enabled again above. We need to trace this, as we're
295 * expected to be enabling interrupts already, but any more
296 * tracing that happens inside the handlers we call for the
297 * pending signals will mess up the tracing state.
300 um_trace_signals_off();
303 * Deal with SIGIO first because the alarm handler might
304 * schedule, leaving the pending SIGIO stranded until we come
307 * SIGIO's handler doesn't use siginfo or mcontext,
308 * so they can be NULL.
310 if (save_pending & SIGIO_MASK)
311 sig_handler_common(SIGIO, NULL, NULL);
313 /* Do not reenter the handler */
315 if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
316 timer_real_alarm_handler(NULL);
318 /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
320 if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
323 /* Re-enable signals and trace that we're doing so. */
324 um_trace_signals_on();
329 int get_signals(void)
331 return signals_enabled;
334 int set_signals(int enable)
337 if (signals_enabled == enable)
340 ret = signals_enabled;
343 else block_signals();
348 int set_signals_trace(int enable)
351 if (signals_enabled == enable)
354 ret = signals_enabled;
356 unblock_signals_trace();
358 block_signals_trace();
363 int os_is_signal_stack(void)
366 sigaltstack(NULL, &ss);
368 return ss.ss_flags & SS_ONSTACK;