1 files changed, 229 insertions, 17 deletions

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index c7bfd5ee3925..f11b3124a0c8 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -4,27 +4,74 @@
  */
 
 #include <signal.h>
-#include "time_user.h"
-#include "mode.h"
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/mman.h>
+#include "user_util.h"
+#include "user.h"
+#include "signal_kern.h"
+#include "sysdep/sigcontext.h"
 #include "sysdep/signal.h"
+#include "sigcontext.h"
+#include "mode.h"
+#include "os.h"
+
+/* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
+ * together under SIGVTALRM_BIT.  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)
+
+#define SIGALRM_BIT 2
+#define SIGALRM_MASK (1 << SIGALRM_BIT)
+
+static int signals_enabled = 1;
+static int pending = 0;
 
 void sig_handler(ARCH_SIGHDLR_PARAM)
 {
 	struct sigcontext *sc;
+	int enabled;
+
+	/* Must be the first thing that this handler does - x86_64 stores
+	 * the sigcontext in %rdx, and we need to save it before it has a
+	 * chance to get trashed.
+	 */
 
 	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!enabled && (sig == SIGIO)){
+		pending |= SIGIO_MASK;
+		return;
+	}
+
+	block_signals();
+
 	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
 			 sig, sc);
+
+	set_signals(enabled);
 }
 
 extern int timer_irq_inited;
 
-void alarm_handler(ARCH_SIGHDLR_PARAM)
+static void real_alarm_handler(int sig, struct sigcontext *sc)
 {
-	struct sigcontext *sc;
-
-	ARCH_GET_SIGCONTEXT(sc, sig);
-	if(!timer_irq_inited) return;
+	if(!timer_irq_inited){
+		signals_enabled = 1;
+		return;
+	}
 
 	if(sig == SIGALRM)
 		switch_timers(0);
@@ -34,15 +81,180 @@ void alarm_handler(ARCH_SIGHDLR_PARAM)
 
 	if(sig == SIGALRM)
 		switch_timers(1);
+
 }
 
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
+void alarm_handler(ARCH_SIGHDLR_PARAM)
+{
+	struct sigcontext *sc;
+	int enabled;
+
+	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!signals_enabled){
+		if(sig == SIGVTALRM)
+			pending |= SIGVTALRM_MASK;
+		else pending |= SIGALRM_MASK;
+
+		return;
+	}
+
+	block_signals();
+
+	real_alarm_handler(sig, sc);
+	set_signals(enabled);
+}
+
+extern void do_boot_timer_handler(struct sigcontext * sc);
+
+void boot_timer_handler(ARCH_SIGHDLR_PARAM)
+{
+	struct sigcontext *sc;
+	int enabled;
+
+	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!enabled){
+		if(sig == SIGVTALRM)
+			pending |= SIGVTALRM_MASK;
+		else pending |= SIGALRM_MASK;
+		return;
+	}
+
+	block_signals();
+
+	do_boot_timer_handler(sc);
+	set_signals(enabled);
+}
+
+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);
+}
+
+void remove_sigstack(void)
+{
+	stack_t stack = ((stack_t) { .ss_flags	= SS_DISABLE,
+				     .ss_sp	= NULL,
+				     .ss_size	= 0 });
+
+	if(sigaltstack(&stack, NULL) != 0)
+		panic("disabling signal stack failed, errno = %d\n", errno);
+}
+
+void set_handler(int sig, void (*handler)(int), int flags, ...)
+{
+	struct sigaction action;
+	va_list ap;
+	sigset_t sig_mask;
+	int mask;
+
+	va_start(ap, flags);
+	action.sa_handler = handler;
+	sigemptyset(&action.sa_mask);
+	while((mask = va_arg(ap, int)) != -1){
+		sigaddset(&action.sa_mask, mask);
+	}
+	va_end(ap);
+	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, old;
+
+	sigemptyset(&sigset);
+	sigaddset(&sigset, signal);
+	sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
+	return(!sigismember(&old, signal));
+}
+
+void block_signals(void)
+{
+	signals_enabled = 0;
+}
+
+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 pending.
+	 */
+	while(1){
+		/* Save and reset save_pending after enabling signals.  This
+		 * way, pending won't be changed while we're reading it.
+		 */
+		signals_enabled = 1;
+
+		save_pending = pending;
+		if(save_pending == 0)
+			return;
+
+		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)
+			CHOOSE_MODE_PROC(sig_handler_common_tt,
+					 sig_handler_common_skas, SIGIO, NULL);
+
+		if(save_pending & SIGALRM_MASK)
+			real_alarm_handler(SIGALRM, NULL);
+
+		if(save_pending & SIGVTALRM_MASK)
+			real_alarm_handler(SIGVTALRM, 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;
+}
+
+void os_usr1_signal(int on)
+{
+	change_sig(SIGUSR1, on);
+}