1 files changed, 59 insertions, 43 deletions

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index e9800b0b5689..0fb0cc8d4757 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -9,11 +9,47 @@
 #include <errno.h>
 #include <signal.h>
 #include <strings.h>
+#include "as-layout.h"
+#include "kern_util.h"
 #include "os.h"
 #include "sysdep/barrier.h"
 #include "sysdep/sigcontext.h"
 #include "user.h"
 
+/* Copied from linux/compiler-gcc.h since we can't include it directly */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+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, struct sigcontext *sc)
+{
+        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. */
+                copy_sc(&r, sc);
+                GET_FAULTINFO_FROM_SC(r.faultinfo, sc);
+        }
+
+        /* 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
@@ -26,13 +62,8 @@
 #define SIGVTALRM_BIT 1
 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
 
-/*
- * These are used by both the signal handlers and
- * block/unblock_signals.  I don't want modifications cached in a
- * register - they must go straight to memory.
- */
-static volatile int signals_enabled = 1;
-static volatile int pending = 0;
+static int signals_enabled;
+static unsigned int signals_pending;
 
 void sig_handler(int sig, struct sigcontext *sc)
 {
@@ -40,13 +71,13 @@ void sig_handler(int sig, struct sigcontext *sc)
 
         enabled = signals_enabled;
         if (!enabled && (sig == SIGIO)) {
-                pending |= SIGIO_MASK;
+                signals_pending |= SIGIO_MASK;
                 return;
         }
 
         block_signals();
 
-        sig_handler_common_skas(sig, sc);
+        sig_handler_common(sig, sc);
 
         set_signals(enabled);
 }
@@ -68,7 +99,7 @@ void alarm_handler(int sig, struct sigcontext *sc)
 
         enabled = signals_enabled;
         if (!signals_enabled) {
-                pending |= SIGVTALRM_MASK;
+                signals_pending |= SIGVTALRM_MASK;
                 return;
         }
 
@@ -94,16 +125,6 @@ void set_sigstack(void *sig_stack, int size)
                 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 (*handlers[_NSIG])(int sig, struct sigcontext *sc);
 
 void handle_signal(int sig, struct sigcontext *sc)
@@ -166,6 +187,9 @@ void set_handler(int sig, void (*handler)(int), int flags, ...)
                 sigaddset(&action.sa_mask, mask);
         va_end(ap);
 
+        if (sig == SIGSEGV)
+                flags |= SA_NODEFER;
+
         action.sa_flags = flags;
         action.sa_restorer = NULL;
         if (sigaction(sig, &action, NULL) < 0)
@@ -179,12 +203,14 @@ void set_handler(int sig, void (*handler)(int), int flags, ...)
 
 int change_sig(int signal, int on)
 {
-        sigset_t sigset, old;
+        sigset_t sigset;
 
         sigemptyset(&sigset);
         sigaddset(&sigset, signal);
-        sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
-        return !sigismember(&old, signal);
+        if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
+                return -errno;
+
+        return 0;
 }
 
 void block_signals(void)
@@ -196,7 +222,7 @@ void block_signals(void)
          * This might matter if gcc figures out how to inline this and
          * decides to shuffle this code into the caller.
          */
-        mb();
+        barrier();
 }
 
 void unblock_signals(void)
@@ -209,36 +235,26 @@ void unblock_signals(void)
         /*
          * 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.
+         * recheck signals_pending.
          */
         while(1) {
                 /*
                  * Save and reset save_pending after enabling signals.  This
-                 * way, pending won't be changed while we're reading it.
+                 * way, signals_pending won't be changed while we're reading it.
                  */
                 signals_enabled = 1;
 
                 /*
-                 * Setting signals_enabled and reading pending must
+                 * Setting signals_enabled and reading signals_pending must
                  * happen in this order.
                  */
-                mb();
-
-                save_pending = pending;
-                if (save_pending == 0) {
-                        /*
-                         * This must return with signals enabled, so
-                         * this barrier ensures that writes are
-                         * flushed out before the return.  This might
-                         * matter if gcc figures out how to inline
-                         * this (unlikely, given its size) and decides
-                         * to shuffle this code into the caller.
-                         */
-                        mb();
+                barrier();
+
+                save_pending = signals_pending;
+                if (save_pending == 0)
                         return;
-                }
 
-                pending = 0;
+                signals_pending = 0;
 
                 /*
                  * We have pending interrupts, so disable signals, as the
@@ -254,7 +270,7 @@ void unblock_signals(void)
                  * back here.
                  */
                 if (save_pending & SIGIO_MASK)
-                        sig_handler_common_skas(SIGIO, NULL);
+                        sig_handler_common(SIGIO, NULL);
 
                 if (save_pending & SIGVTALRM_MASK)
                         real_alarm_handler(NULL);