hw-breakpoints: reset bits in dr6 after the corresponding exception is handled

This patch resets the bit in dr6 after the corresponding exception is
handled in code, so that we keep a clean track of the current virtual debug
status register.

[ Impact: keep track of breakpoints triggering completion ]

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 16ccbd77917f..11a4ad4d6253 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -540,8 +540,14 @@ kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
         struct die_args *arg = args;
 
         if (val == DIE_DEBUG && (arg->err & DR_STEP))
-                if (post_kmmio_handler(arg->err, arg->regs) == 1)
+                if (post_kmmio_handler(arg->err, arg->regs) == 1) {
+                        /*
+                         * Reset the BS bit in dr6 (pointed by args->err) to
+                         * denote completion of processing
+                         */
+                        (*(unsigned long *)ERR_PTR(arg->err)) &= ~DR_STEP;
                         return NOTIFY_STOP;
+                }
 
         return NOTIFY_DONE;
 }