3 files changed, 36 insertions, 13 deletions

diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index ab4ebb856c2a..b46728027195 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -224,7 +224,7 @@ work_resched:
 syscall_exit_work:
         ! r0: current_thread_info->flags
         ! r8: current_thread_info
-        tst     #_TIF_SYSCALL_TRACE, r0
+        tst     #_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP, r0
         bt/s    work_pending
          tst    #_TIF_NEED_RESCHED, r0
 #ifdef CONFIG_TRACE_IRQFLAGS
diff --git a/arch/sh/kernel/ptrace.c b/arch/sh/kernel/ptrace.c
index 04ca13a041c1..855f7246cfff 100644
--- a/arch/sh/kernel/ptrace.c
+++ b/arch/sh/kernel/ptrace.c
@@ -8,7 +8,6 @@
  * SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
  *
  */
-
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -20,8 +19,7 @@
 #include <linux/slab.h>
 #include <linux/security.h>
 #include <linux/signal.h>
-
-#include <asm/io.h>
+#include <linux/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -59,6 +57,23 @@ static inline int put_stack_long(struct task_struct *task, int offset,
         return 0;
 }
 
+static void ptrace_disable_singlestep(struct task_struct *child)
+{
+        clear_tsk_thread_flag(child, TIF_SINGLESTEP);
+
+        /*
+         * Ensure the UBC is not programmed at the next context switch.
+         *
+         * Normally this is not needed but there are sequences such as
+         * singlestep, signal delivery, and continue that leave the
+         * ubc_pc non-zero leading to spurious SIGTRAPs.
+         */
+        if (child->thread.ubc_pc != 0) {
+                ubc_usercnt -= 1;
+                child->thread.ubc_pc = 0;
+        }
+}
+
 /*
  * Called by kernel/ptrace.c when detaching..
  *
@@ -66,7 +81,7 @@ static inline int put_stack_long(struct task_struct *task, int offset,
  */
 void ptrace_disable(struct task_struct *child)
 {
-        /* nothing to do.. */
+        ptrace_disable_singlestep(child);
 }
 
 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
@@ -76,7 +91,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 
         switch (request) {
         /* when I and D space are separate, these will need to be fixed. */
-        case PTRACE_PEEKTEXT: /* read word at location addr. */ 
+        case PTRACE_PEEKTEXT: /* read word at location addr. */
         case PTRACE_PEEKDATA: {
                 unsigned long tmp;
                 int copied;
@@ -94,7 +109,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 unsigned long tmp;
 
                 ret = -EIO;
-                if ((addr & 3) || addr < 0 || 
+                if ((addr & 3) || addr < 0 ||
                     addr > sizeof(struct user) - 3)
                         break;
 
@@ -129,7 +144,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 
         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
                 ret = -EIO;
-                if ((addr & 3) || addr < 0 || 
+                if ((addr & 3) || addr < 0 ||
                     addr > sizeof(struct user) - 3)
                         break;
 
@@ -156,6 +171,9 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                         set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                 else
                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+                ptrace_disable_singlestep(child);
+
                 child->exit_code = data;
                 wake_up_process(child);
                 ret = 0;
@@ -163,14 +181,15 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
         }
 
 /*
- * make the child exit.  Best I can do is send it a sigkill. 
- * perhaps it should be put in the status that it wants to 
+ * make the child exit.  Best I can do is send it a sigkill.
+ * perhaps it should be put in the status that it wants to
  * exit.
  */
         case PTRACE_KILL: {
                 ret = 0;
                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
                         break;
+                ptrace_disable_singlestep(child);
                 child->exit_code = SIGKILL;
                 wake_up_process(child);
                 break;
@@ -196,6 +215,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                         ubc_usercnt += 1;
                 child->thread.ubc_pc = pc;
 
+                set_tsk_thread_flag(child, TIF_SINGLESTEP);
                 child->exit_code = data;
                 /* give it a chance to run. */
                 wake_up_process(child);
@@ -248,14 +268,15 @@ asmlinkage void do_syscall_trace(void)
 {
         struct task_struct *tsk = current;
 
-        if (!test_thread_flag(TIF_SYSCALL_TRACE))
+        if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
+            !test_thread_flag(TIF_SINGLESTEP))
                 return;
         if (!(tsk->ptrace & PT_PTRACED))
                 return;
         /* the 0x80 provides a way for the tracing parent to distinguish
            between a syscall stop and SIGTRAP delivery */
-        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-                                 ? 0x80 : 0));
+        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
+                                 !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
 
         /*
          * this isn't the same as continuing with a signal, but it will do
diff --git a/include/asm-sh/thread_info.h b/include/asm-sh/thread_info.h
index 279e70a77c75..31d55e3782d5 100644
--- a/include/asm-sh/thread_info.h
+++ b/include/asm-sh/thread_info.h
@@ -111,6 +111,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SIGPENDING          2       /* signal pending */
 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
 #define TIF_RESTORE_SIGMASK     4       /* restore signal mask in do_signal() */
+#define TIF_SINGLESTEP          5       /* singlestepping active */
 #define TIF_USEDFPU             16      /* FPU was used by this task this quantum (SMP) */
 #define TIF_POLLING_NRFLAG      17      /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE              18
@@ -121,6 +122,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_SINGLESTEP         (1<<TIF_SINGLESTEP)
 #define _TIF_USEDFPU            (1<<TIF_USEDFPU)
 #define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)