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377 lines
8.2 KiB
377 lines
8.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk}) |
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* Copyright (C) 2015 Thomas Meyer ([email protected]) |
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* Copyright (C) 2004 PathScale, Inc |
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* Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
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*/ |
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#include <stdlib.h> |
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#include <stdarg.h> |
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#include <errno.h> |
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#include <signal.h> |
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#include <string.h> |
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#include <strings.h> |
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#include <as-layout.h> |
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#include <kern_util.h> |
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#include <os.h> |
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#include <sysdep/mcontext.h> |
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#include <um_malloc.h> |
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#include <sys/ucontext.h> |
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void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { |
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[SIGTRAP] = relay_signal, |
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[SIGFPE] = relay_signal, |
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[SIGILL] = relay_signal, |
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[SIGWINCH] = winch, |
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[SIGBUS] = bus_handler, |
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[SIGSEGV] = segv_handler, |
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[SIGIO] = sigio_handler, |
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}; |
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static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) |
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{ |
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struct uml_pt_regs r; |
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int save_errno = errno; |
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r.is_user = 0; |
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if (sig == SIGSEGV) { |
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/* For segfaults, we want the data from the sigcontext. */ |
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get_regs_from_mc(&r, mc); |
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GET_FAULTINFO_FROM_MC(r.faultinfo, mc); |
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} |
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/* enable signals if sig isn't IRQ signal */ |
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if ((sig != SIGIO) && (sig != SIGWINCH)) |
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unblock_signals_trace(); |
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(*sig_info[sig])(sig, si, &r); |
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errno = save_errno; |
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} |
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/* |
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* These are the asynchronous signals. SIGPROF is excluded because we want to |
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* be able to profile all of UML, not just the non-critical sections. If |
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* profiling is not thread-safe, then that is not my problem. We can disable |
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* profiling when SMP is enabled in that case. |
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*/ |
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#define SIGIO_BIT 0 |
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#define SIGIO_MASK (1 << SIGIO_BIT) |
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#define SIGALRM_BIT 1 |
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#define SIGALRM_MASK (1 << SIGALRM_BIT) |
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static int signals_enabled; |
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static unsigned int signals_pending; |
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static unsigned int signals_active = 0; |
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void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) |
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{ |
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int enabled; |
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enabled = signals_enabled; |
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if (!enabled && (sig == SIGIO)) { |
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signals_pending |= SIGIO_MASK; |
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return; |
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} |
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block_signals_trace(); |
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sig_handler_common(sig, si, mc); |
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set_signals_trace(enabled); |
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} |
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static void timer_real_alarm_handler(mcontext_t *mc) |
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{ |
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struct uml_pt_regs regs; |
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if (mc != NULL) |
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get_regs_from_mc(®s, mc); |
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else |
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memset(®s, 0, sizeof(regs)); |
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timer_handler(SIGALRM, NULL, ®s); |
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} |
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void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) |
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{ |
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int enabled; |
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enabled = signals_enabled; |
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if (!signals_enabled) { |
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signals_pending |= SIGALRM_MASK; |
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return; |
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} |
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block_signals_trace(); |
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signals_active |= SIGALRM_MASK; |
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timer_real_alarm_handler(mc); |
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signals_active &= ~SIGALRM_MASK; |
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set_signals_trace(enabled); |
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} |
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void deliver_alarm(void) { |
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timer_alarm_handler(SIGALRM, NULL, NULL); |
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} |
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void timer_set_signal_handler(void) |
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{ |
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set_handler(SIGALRM); |
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} |
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void set_sigstack(void *sig_stack, int size) |
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{ |
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stack_t stack = { |
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.ss_flags = 0, |
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.ss_sp = sig_stack, |
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.ss_size = size - sizeof(void *) |
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}; |
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if (sigaltstack(&stack, NULL) != 0) |
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panic("enabling signal stack failed, errno = %d\n", errno); |
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} |
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static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) |
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{ |
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uml_pm_wake(); |
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} |
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void register_pm_wake_signal(void) |
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{ |
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set_handler(SIGUSR1); |
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} |
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static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = { |
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[SIGSEGV] = sig_handler, |
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[SIGBUS] = sig_handler, |
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[SIGILL] = sig_handler, |
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[SIGFPE] = sig_handler, |
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[SIGTRAP] = sig_handler, |
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[SIGIO] = sig_handler, |
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[SIGWINCH] = sig_handler, |
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[SIGALRM] = timer_alarm_handler, |
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[SIGUSR1] = sigusr1_handler, |
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}; |
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static void hard_handler(int sig, siginfo_t *si, void *p) |
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{ |
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ucontext_t *uc = p; |
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mcontext_t *mc = &uc->uc_mcontext; |
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unsigned long pending = 1UL << sig; |
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do { |
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int nested, bail; |
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/* |
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* pending comes back with one bit set for each |
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* interrupt that arrived while setting up the stack, |
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* plus a bit for this interrupt, plus the zero bit is |
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* set if this is a nested interrupt. |
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* If bail is true, then we interrupted another |
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* handler setting up the stack. In this case, we |
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* have to return, and the upper handler will deal |
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* with this interrupt. |
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*/ |
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bail = to_irq_stack(&pending); |
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if (bail) |
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return; |
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nested = pending & 1; |
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pending &= ~1; |
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while ((sig = ffs(pending)) != 0){ |
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sig--; |
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pending &= ~(1 << sig); |
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(*handlers[sig])(sig, (struct siginfo *)si, mc); |
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} |
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/* |
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* Again, pending comes back with a mask of signals |
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* that arrived while tearing down the stack. If this |
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* is non-zero, we just go back, set up the stack |
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* again, and handle the new interrupts. |
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*/ |
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if (!nested) |
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pending = from_irq_stack(nested); |
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} while (pending); |
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} |
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void set_handler(int sig) |
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{ |
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struct sigaction action; |
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int flags = SA_SIGINFO | SA_ONSTACK; |
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sigset_t sig_mask; |
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action.sa_sigaction = hard_handler; |
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/* block irq ones */ |
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sigemptyset(&action.sa_mask); |
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sigaddset(&action.sa_mask, SIGIO); |
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sigaddset(&action.sa_mask, SIGWINCH); |
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sigaddset(&action.sa_mask, SIGALRM); |
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if (sig == SIGSEGV) |
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flags |= SA_NODEFER; |
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if (sigismember(&action.sa_mask, sig)) |
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flags |= SA_RESTART; /* if it's an irq signal */ |
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action.sa_flags = flags; |
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action.sa_restorer = NULL; |
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if (sigaction(sig, &action, NULL) < 0) |
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panic("sigaction failed - errno = %d\n", errno); |
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sigemptyset(&sig_mask); |
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sigaddset(&sig_mask, sig); |
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if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) |
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panic("sigprocmask failed - errno = %d\n", errno); |
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} |
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void send_sigio_to_self(void) |
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{ |
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kill(os_getpid(), SIGIO); |
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} |
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int change_sig(int signal, int on) |
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{ |
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sigset_t sigset; |
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sigemptyset(&sigset); |
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sigaddset(&sigset, signal); |
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if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) |
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return -errno; |
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return 0; |
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} |
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void block_signals(void) |
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{ |
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signals_enabled = 0; |
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/* |
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* This must return with signals disabled, so this barrier |
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* ensures that writes are flushed out before the return. |
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* This might matter if gcc figures out how to inline this and |
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* decides to shuffle this code into the caller. |
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*/ |
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barrier(); |
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} |
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void unblock_signals(void) |
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{ |
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int save_pending; |
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if (signals_enabled == 1) |
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return; |
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signals_enabled = 1; |
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#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT |
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deliver_time_travel_irqs(); |
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#endif |
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/* |
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* We loop because the IRQ handler returns with interrupts off. So, |
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* interrupts may have arrived and we need to re-enable them and |
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* recheck signals_pending. |
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*/ |
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while (1) { |
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/* |
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* Save and reset save_pending after enabling signals. This |
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* way, signals_pending won't be changed while we're reading it. |
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* |
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* Setting signals_enabled and reading signals_pending must |
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* happen in this order, so have the barrier here. |
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*/ |
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barrier(); |
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save_pending = signals_pending; |
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if (save_pending == 0) |
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return; |
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signals_pending = 0; |
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/* |
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* We have pending interrupts, so disable signals, as the |
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* handlers expect them off when they are called. They will |
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* be enabled again above. We need to trace this, as we're |
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* expected to be enabling interrupts already, but any more |
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* tracing that happens inside the handlers we call for the |
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* pending signals will mess up the tracing state. |
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*/ |
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signals_enabled = 0; |
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um_trace_signals_off(); |
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/* |
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* Deal with SIGIO first because the alarm handler might |
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* schedule, leaving the pending SIGIO stranded until we come |
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* back here. |
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* |
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* SIGIO's handler doesn't use siginfo or mcontext, |
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* so they can be NULL. |
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*/ |
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if (save_pending & SIGIO_MASK) |
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sig_handler_common(SIGIO, NULL, NULL); |
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/* Do not reenter the handler */ |
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if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK))) |
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timer_real_alarm_handler(NULL); |
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/* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */ |
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if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK)) |
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return; |
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/* Re-enable signals and trace that we're doing so. */ |
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um_trace_signals_on(); |
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signals_enabled = 1; |
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} |
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} |
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int get_signals(void) |
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{ |
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return signals_enabled; |
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} |
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int set_signals(int enable) |
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{ |
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int ret; |
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if (signals_enabled == enable) |
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return enable; |
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ret = signals_enabled; |
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if (enable) |
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unblock_signals(); |
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else block_signals(); |
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return ret; |
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} |
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int set_signals_trace(int enable) |
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{ |
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int ret; |
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if (signals_enabled == enable) |
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return enable; |
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ret = signals_enabled; |
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if (enable) |
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unblock_signals_trace(); |
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else |
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block_signals_trace(); |
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return ret; |
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} |
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int os_is_signal_stack(void) |
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{ |
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stack_t ss; |
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sigaltstack(NULL, &ss); |
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return ss.ss_flags & SS_ONSTACK; |
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}
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