![Hans-Werner Hilse](/assets/img/avatar_default.png)
__ptr_t type is a glibc-specific type, while the generally documented type is a void*. That's what other C libraries use, too. Signed-off-by: Hans-Werner Hilse <hwhilse@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at>
317 lines
6.7 KiB
C
317 lines
6.7 KiB
C
/*
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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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* Licensed under the GPL
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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 <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 "internal.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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[SIGVTALRM] = timer_handler };
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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) && (sig != SIGVTALRM))
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unblock_signals();
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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 SIGVTALRM_BIT 1
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#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
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static int signals_enabled;
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static unsigned int signals_pending;
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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();
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sig_handler_common(sig, si, mc);
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set_signals(enabled);
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}
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static void 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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regs.is_user = 0;
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unblock_signals();
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timer_handler(SIGVTALRM, NULL, ®s);
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}
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void 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 |= SIGVTALRM_MASK;
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return;
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}
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block_signals();
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real_alarm_handler(mc);
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set_signals(enabled);
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}
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void timer_init(void)
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{
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set_handler(SIGVTALRM);
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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 (*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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[SIGVTALRM] = alarm_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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struct ucontext *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, SIGVTALRM);
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sigaddset(&action.sa_mask, SIGIO);
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sigaddset(&action.sa_mask, SIGWINCH);
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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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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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/*
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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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signals_enabled = 1;
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/*
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* Setting signals_enabled and reading signals_pending must
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* happen in this order.
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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.
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*/
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signals_enabled = 0;
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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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if (save_pending & SIGVTALRM_MASK)
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real_alarm_handler(NULL);
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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 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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