3 files changed, 40 insertions, 11 deletions

diff --git a/arch/sparc/include/asm/ptrace_64.h b/arch/sparc/include/asm/ptrace_64.h
index ec6d45c84cd0..390d92ac67cf 100644
--- a/arch/sparc/include/asm/ptrace_64.h
+++ b/arch/sparc/include/asm/ptrace_64.h
@@ -134,9 +134,9 @@ struct global_reg_snapshot {
         unsigned long           tnpc;
         unsigned long           o7;
         unsigned long           i7;
+        unsigned long           rpc;
         struct thread_info      *thread;
         unsigned long           pad1;
-        unsigned long           pad2;
 };
 
 #define __ARCH_WANT_COMPAT_SYS_PTRACE
@@ -315,9 +315,9 @@ extern void __show_regs(struct pt_regs *);
 #define GR_SNAP_TNPC    0x10
 #define GR_SNAP_O7      0x18
 #define GR_SNAP_I7      0x20
-#define GR_SNAP_THREAD  0x28
-#define GR_SNAP_PAD1    0x30
-#define GR_SNAP_PAD2    0x38
+#define GR_SNAP_RPC     0x28
+#define GR_SNAP_THREAD  0x30
+#define GR_SNAP_PAD1    0x38
 
 #endif  /*  __KERNEL__  */
 
diff --git a/arch/sparc64/kernel/process.c b/arch/sparc64/kernel/process.c
index 0f60547c24d9..fc8137a21ced 100644
--- a/arch/sparc64/kernel/process.c
+++ b/arch/sparc64/kernel/process.c
@@ -304,6 +304,19 @@ void show_regs(struct pt_regs *regs)
 struct global_reg_snapshot global_reg_snapshot[NR_CPUS];
 static DEFINE_SPINLOCK(global_reg_snapshot_lock);
 
+static bool kstack_valid(struct thread_info *tp, struct reg_window *rw)
+{
+        unsigned long thread_base, fp;
+
+        thread_base = (unsigned long) tp;
+        fp = (unsigned long) rw;
+
+        if (fp < (thread_base + sizeof(struct thread_info)) ||
+            fp >= (thread_base + THREAD_SIZE))
+                return false;
+        return true;
+}
+
 static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
                               int this_cpu)
 {
@@ -315,14 +328,22 @@ static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
         global_reg_snapshot[this_cpu].o7 = regs->u_regs[UREG_I7];
 
         if (regs->tstate & TSTATE_PRIV) {
+                struct thread_info *tp = current_thread_info();
                 struct reg_window *rw;
 
                 rw = (struct reg_window *)
                         (regs->u_regs[UREG_FP] + STACK_BIAS);
-                global_reg_snapshot[this_cpu].i7 = rw->ins[7];
-        } else
+                if (kstack_valid(tp, rw)) {
+                        global_reg_snapshot[this_cpu].i7 = rw->ins[7];
+                        rw = (struct reg_window *)
+                                (rw->ins[6] + STACK_BIAS);
+                        if (kstack_valid(tp, rw))
+                                global_reg_snapshot[this_cpu].rpc = rw->ins[7];
+                }
+        } else {
                 global_reg_snapshot[this_cpu].i7 = 0;
-
+                global_reg_snapshot[this_cpu].rpc = 0;
+        }
         global_reg_snapshot[this_cpu].thread = tp;
 }
 
@@ -375,13 +396,14 @@ static void sysrq_handle_globreg(int key, struct tty_struct *tty)
                        ((tp && tp->task) ? tp->task->pid : -1));
 
                 if (gp->tstate & TSTATE_PRIV) {
-                        printk("             TPC[%pS] O7[%pS] I7[%pS]\n",
+                        printk("             TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
                                (void *) gp->tpc,
                                (void *) gp->o7,
-                               (void *) gp->i7);
+                               (void *) gp->i7,
+                               (void *) gp->rpc);
                 } else {
-                        printk("             TPC[%lx] O7[%lx] I7[%lx]\n",
-                               gp->tpc, gp->o7, gp->i7);
+                        printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
+                               gp->tpc, gp->o7, gp->i7, gp->rpc);
                 }
         }
 
diff --git a/arch/sparc64/mm/ultra.S b/arch/sparc64/mm/ultra.S
index 4c8ca131ffaf..77ba88597cc5 100644
--- a/arch/sparc64/mm/ultra.S
+++ b/arch/sparc64/mm/ultra.S
@@ -531,6 +531,13 @@ xcall_fetch_glob_regs:
         stx             %g7, [%g1 + GR_SNAP_TNPC]
         stx             %o7, [%g1 + GR_SNAP_O7]
         stx             %i7, [%g1 + GR_SNAP_I7]
+        /* Don't try this at home kids... */
+        rdpr            %cwp, %g2
+        sub             %g2, 1, %g7
+        wrpr            %g7, %cwp
+        mov             %i7, %g7
+        wrpr            %g2, %cwp
+        stx             %g7, [%g1 + GR_SNAP_RPC]
         sethi           %hi(trap_block), %g7
         or              %g7, %lo(trap_block), %g7
         sllx            %g2, TRAP_BLOCK_SZ_SHIFT, %g2