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>
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 4867c9f..6945147 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -314,8 +314,12 @@
{
int i, cpu, rc = NOTIFY_STOP;
struct hw_breakpoint *bp;
- /* The DR6 value is stored in args->err */
- unsigned long dr7, dr6 = args->err;
+ unsigned long dr7, dr6;
+ unsigned long *dr6_p;
+
+ /* The DR6 value is pointed by args->err */
+ dr6_p = (unsigned long *)ERR_PTR(args->err);
+ dr6 = *dr6_p;
/* Do an early return if no trap bits are set in DR6 */
if ((dr6 & DR_TRAP_BITS) == 0)
@@ -352,6 +356,11 @@
rc = NOTIFY_DONE;
}
/*
+ * Reset the 'i'th TRAP bit in dr6 to denote completion of
+ * exception handling
+ */
+ (*dr6_p) &= ~(DR_TRAP0 << i);
+ /*
* bp can be NULL due to lazy debug register switching
* or due to the delay between updates of hbp_kernel_pos
* and this_hbp_kernel.
