3 files changed, 43 insertions, 27 deletions

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 2caa556db86d..2e86fd1ddc7b 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -822,21 +822,23 @@ static inline void syscall_restart32(unsigned long orig_i0, struct pt_regs *regs
  * want to handle. Thus you cannot kill init even with a SIGKILL even by
  * mistake.
  */
-void do_signal32(sigset_t *oldset, struct pt_regs * regs,
-                 int restart_syscall, unsigned long orig_i0)
+void do_signal32(sigset_t *oldset, struct pt_regs * regs)
 {
         struct k_sigaction ka;
+        unsigned long orig_i0;
+        int restart_syscall;
         siginfo_t info;
         int signr;
         
         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 
-        /* If the debugger messes with the program counter, it clears
-         * the "in syscall" bit, directing us to not perform a syscall
-         * restart.
-         */
-        if (restart_syscall && !pt_regs_is_syscall(regs))
-                restart_syscall = 0;
+        restart_syscall = 0;
+        orig_i0 = 0;
+        if (pt_regs_is_syscall(regs) &&
+            (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
+                restart_syscall = 1;
+                orig_i0 = regs->u_regs[UREG_G2];
+        }
 
         if (signr > 0) {
                 if (restart_syscall)
diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c
index 8ce247ac04cc..7dfaff64cd6b 100644
--- a/arch/sparc/kernel/signal_32.c
+++ b/arch/sparc/kernel/signal_32.c
@@ -519,10 +519,16 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
         siginfo_t info;
         int signr;
 
+        /* It's a lot of work and synchronization to add a new ptrace
+         * register for GDB to save and restore in order to get
+         * orig_i0 correct for syscall restarts when debugging.
+         *
+         * However, we luckily can use the fact that several registers
+         * are volatile across system calls.  One such register is
+         * %g2, so use that as a place to save away orig_i0.
+         */
         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
-                restart_syscall = 1;
-        else
-                restart_syscall = 0;
+                regs->u_regs[UREG_G2] = orig_i0;
 
         if (test_thread_flag(TIF_RESTORE_SIGMASK))
                 oldset = &current->saved_sigmask;
@@ -535,8 +541,12 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
          * the software "in syscall" bit, directing us to not perform
          * a syscall restart.
          */
-        if (restart_syscall && !pt_regs_is_syscall(regs))
-                restart_syscall = 0;
+        restart_syscall = 0;
+        if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
+                restart_syscall = 1;
+                orig_i0 = regs->u_regs[UREG_G2];
+        }
+
 
         if (signr > 0) {
                 if (restart_syscall)
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a2b81598d905..1ddf0dedb929 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -529,11 +529,17 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
         siginfo_t info;
         int signr;
         
+        /* It's a lot of work and synchronization to add a new ptrace
+         * register for GDB to save and restore in order to get
+         * orig_i0 correct for syscall restarts when debugging.
+         *
+         * However, we luckily can use the fact that several registers
+         * are volatile across system calls.  One such register is
+         * %g2, so use that as a place to save away orig_i0.
+         */
         if (pt_regs_is_syscall(regs) &&
-            (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
-                restart_syscall = 1;
-        } else
-                restart_syscall = 0;
+            (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY)))
+                regs->u_regs[UREG_G2] = orig_i0;
 
         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
                 oldset = &current->saved_sigmask;
@@ -542,22 +548,20 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 
 #ifdef CONFIG_COMPAT
         if (test_thread_flag(TIF_32BIT)) {
-                extern void do_signal32(sigset_t *, struct pt_regs *,
-                                        int restart_syscall,
-                                        unsigned long orig_i0);
-                do_signal32(oldset, regs, restart_syscall, orig_i0);
+                extern void do_signal32(sigset_t *, struct pt_regs *);
+                do_signal32(oldset, regs);
                 return;
         }
 #endif  
 
         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 
-        /* If the debugger messes with the program counter, it clears
-         * the software "in syscall" bit, directing us to not perform
-         * a syscall restart.
-         */
-        if (restart_syscall && !pt_regs_is_syscall(regs))
-                restart_syscall = 0;
+        restart_syscall = 0;
+        if (pt_regs_is_syscall(regs) &&
+            (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
+                restart_syscall = 1;
+                orig_i0 = regs->u_regs[UREG_G2];
+        }
 
         if (signr > 0) {
                 if (restart_syscall)