powerpc: Fix booke user_disable_single_step()

On booke processors, gdb is seeing spurious SIGTRAPs when setting a
watchpoint.

user_disable_single_step() simply quits when the DAC is non-zero.  It should
be clearing the DBCR0_IC and DBCR0_BT bits from the dbcr0 register and
TIF_SINGLESTEP from the thread flag.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 9fa2c7dcd05a..ef149880c145 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -736,15 +736,16 @@ void user_disable_single_step(struct task_struct *task)
 {
         struct pt_regs *regs = task->thread.regs;
 
-
-#if defined(CONFIG_BOOKE)
-        /* If DAC then do not single step, skip */
-        if (task->thread.dabr)
-                return;
-#endif
-
         if (regs != NULL) {
-#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
+#if defined(CONFIG_BOOKE)
+                /* If DAC don't clear DBCRO_IDM or MSR_DE */
+                if (task->thread.dabr)
+                        task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT);
+                else {
+                        task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT | DBCR0_IDM);
+                        regs->msr &= ~MSR_DE;
+                }
+#elif defined(CONFIG_40x)
                 task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT | DBCR0_IDM);
                 regs->msr &= ~MSR_DE;
 #else