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authorAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
committerAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /arch/um/os-Linux/signal.c
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
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fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'arch/um/os-Linux/signal.c')
-rw-r--r--arch/um/os-Linux/signal.c302
1 files changed, 302 insertions, 0 deletions
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
new file mode 100644
index 00000000000..2d22f1fcd8e
--- /dev/null
+++ b/arch/um/os-Linux/signal.c
@@ -0,0 +1,302 @@
+/*
+ * Copyright (C) 2004 PathScale, Inc
+ * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <signal.h>
+#include <strings.h>
+#include "as-layout.h"
+#include "kern_util.h"
+#include "os.h"
+#include "sysdep/mcontext.h"
+
+void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
+ [SIGTRAP] = relay_signal,
+ [SIGFPE] = relay_signal,
+ [SIGILL] = relay_signal,
+ [SIGWINCH] = winch,
+ [SIGBUS] = bus_handler,
+ [SIGSEGV] = segv_handler,
+ [SIGIO] = sigio_handler,
+ [SIGVTALRM] = timer_handler };
+
+static void sig_handler_common(int sig, mcontext_t *mc)
+{
+ struct uml_pt_regs r;
+ int save_errno = errno;
+
+ r.is_user = 0;
+ if (sig == SIGSEGV) {
+ /* For segfaults, we want the data from the sigcontext. */
+ get_regs_from_mc(&r, mc);
+ GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
+ }
+
+ /* enable signals if sig isn't IRQ signal */
+ if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
+ unblock_signals();
+
+ (*sig_info[sig])(sig, &r);
+
+ errno = save_errno;
+}
+
+/*
+ * These are the asynchronous signals. SIGPROF is excluded because we want to
+ * be able to profile all of UML, not just the non-critical sections. If
+ * profiling is not thread-safe, then that is not my problem. We can disable
+ * profiling when SMP is enabled in that case.
+ */
+#define SIGIO_BIT 0
+#define SIGIO_MASK (1 << SIGIO_BIT)
+
+#define SIGVTALRM_BIT 1
+#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
+
+static int signals_enabled;
+static unsigned int signals_pending;
+
+void sig_handler(int sig, mcontext_t *mc)
+{
+ int enabled;
+
+ enabled = signals_enabled;
+ if (!enabled && (sig == SIGIO)) {
+ signals_pending |= SIGIO_MASK;
+ return;
+ }
+
+ block_signals();
+
+ sig_handler_common(sig, mc);
+
+ set_signals(enabled);
+}
+
+static void real_alarm_handler(mcontext_t *mc)
+{
+ struct uml_pt_regs regs;
+
+ if (mc != NULL)
+ get_regs_from_mc(&regs, mc);
+ regs.is_user = 0;
+ unblock_signals();
+ timer_handler(SIGVTALRM, &regs);
+}
+
+void alarm_handler(int sig, mcontext_t *mc)
+{
+ int enabled;
+
+ enabled = signals_enabled;
+ if (!signals_enabled) {
+ signals_pending |= SIGVTALRM_MASK;
+ return;
+ }
+
+ block_signals();
+
+ real_alarm_handler(mc);
+ set_signals(enabled);
+}
+
+void timer_init(void)
+{
+ set_handler(SIGVTALRM);
+}
+
+void set_sigstack(void *sig_stack, int size)
+{
+ stack_t stack = ((stack_t) { .ss_flags = 0,
+ .ss_sp = (__ptr_t) sig_stack,
+ .ss_size = size - sizeof(void *) });
+
+ if (sigaltstack(&stack, NULL) != 0)
+ panic("enabling signal stack failed, errno = %d\n", errno);
+}
+
+static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = {
+ [SIGSEGV] = sig_handler,
+ [SIGBUS] = sig_handler,
+ [SIGILL] = sig_handler,
+ [SIGFPE] = sig_handler,
+ [SIGTRAP] = sig_handler,
+
+ [SIGIO] = sig_handler,
+ [SIGWINCH] = sig_handler,
+ [SIGVTALRM] = alarm_handler
+};
+
+
+static void hard_handler(int sig, siginfo_t *info, void *p)
+{
+ struct ucontext *uc = p;
+ mcontext_t *mc = &uc->uc_mcontext;
+ unsigned long pending = 1UL << sig;
+
+ do {
+ int nested, bail;
+
+ /*
+ * pending comes back with one bit set for each
+ * interrupt that arrived while setting up the stack,
+ * plus a bit for this interrupt, plus the zero bit is
+ * set if this is a nested interrupt.
+ * If bail is true, then we interrupted another
+ * handler setting up the stack. In this case, we
+ * have to return, and the upper handler will deal
+ * with this interrupt.
+ */
+ bail = to_irq_stack(&pending);
+ if (bail)
+ return;
+
+ nested = pending & 1;
+ pending &= ~1;
+
+ while ((sig = ffs(pending)) != 0){
+ sig--;
+ pending &= ~(1 << sig);
+ (*handlers[sig])(sig, mc);
+ }
+
+ /*
+ * Again, pending comes back with a mask of signals
+ * that arrived while tearing down the stack. If this
+ * is non-zero, we just go back, set up the stack
+ * again, and handle the new interrupts.
+ */
+ if (!nested)
+ pending = from_irq_stack(nested);
+ } while (pending);
+}
+
+void set_handler(int sig)
+{
+ struct sigaction action;
+ int flags = SA_SIGINFO | SA_ONSTACK;
+ sigset_t sig_mask;
+
+ action.sa_sigaction = hard_handler;
+
+ /* block irq ones */
+ sigemptyset(&action.sa_mask);
+ sigaddset(&action.sa_mask, SIGVTALRM);
+ sigaddset(&action.sa_mask, SIGIO);
+ sigaddset(&action.sa_mask, SIGWINCH);
+
+ if (sig == SIGSEGV)
+ flags |= SA_NODEFER;
+
+ if (sigismember(&action.sa_mask, sig))
+ flags |= SA_RESTART; /* if it's an irq signal */
+
+ action.sa_flags = flags;
+ action.sa_restorer = NULL;
+ if (sigaction(sig, &action, NULL) < 0)
+ panic("sigaction failed - errno = %d\n", errno);
+
+ sigemptyset(&sig_mask);
+ sigaddset(&sig_mask, sig);
+ if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
+ panic("sigprocmask failed - errno = %d\n", errno);
+}
+
+int change_sig(int signal, int on)
+{
+ sigset_t sigset;
+
+ sigemptyset(&sigset);
+ sigaddset(&sigset, signal);
+ if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
+ return -errno;
+
+ return 0;
+}
+
+void block_signals(void)
+{
+ signals_enabled = 0;
+ /*
+ * This must return with signals disabled, so this barrier
+ * ensures that writes are flushed out before the return.
+ * This might matter if gcc figures out how to inline this and
+ * decides to shuffle this code into the caller.
+ */
+ barrier();
+}
+
+void unblock_signals(void)
+{
+ int save_pending;
+
+ if (signals_enabled == 1)
+ return;
+
+ /*
+ * We loop because the IRQ handler returns with interrupts off. So,
+ * interrupts may have arrived and we need to re-enable them and
+ * recheck signals_pending.
+ */
+ while (1) {
+ /*
+ * Save and reset save_pending after enabling signals. This
+ * way, signals_pending won't be changed while we're reading it.
+ */
+ signals_enabled = 1;
+
+ /*
+ * Setting signals_enabled and reading signals_pending must
+ * happen in this order.
+ */
+ barrier();
+
+ save_pending = signals_pending;
+ if (save_pending == 0)
+ return;
+
+ signals_pending = 0;
+
+ /*
+ * We have pending interrupts, so disable signals, as the
+ * handlers expect them off when they are called. They will
+ * be enabled again above.
+ */
+
+ signals_enabled = 0;
+
+ /*
+ * Deal with SIGIO first because the alarm handler might
+ * schedule, leaving the pending SIGIO stranded until we come
+ * back here.
+ */
+ if (save_pending & SIGIO_MASK)
+ sig_handler_common(SIGIO, NULL);
+
+ if (save_pending & SIGVTALRM_MASK)
+ real_alarm_handler(NULL);
+ }
+}
+
+int get_signals(void)
+{
+ return signals_enabled;
+}
+
+int set_signals(int enable)
+{
+ int ret;
+ if (signals_enabled == enable)
+ return enable;
+
+ ret = signals_enabled;
+ if (enable)
+ unblock_signals();
+ else block_signals();
+
+ return ret;
+}