ARM: hw_breakpoint: disable preemption during debug exception handling

[mv-sheeva.git] / arch / arm / kernel / hw_breakpoint.c

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index d37ed3501e5700a515510c34b01d02517bdc784f..eeba3800803249f0e7d8c0700afdcb84817701dd 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -24,6 +24,7 @@
 #define pr_fmt(fmt) "hw-breakpoint: " fmt
 
 #include <linux/errno.h>
+#include <linux/hardirq.h>
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/smp.h>
@@ -736,14 +737,17 @@ unlock:
 
 /*
  * Called from either the Data Abort Handler [watchpoint] or the
- * Prefetch Abort Handler [breakpoint].
+ * Prefetch Abort Handler [breakpoint] with preemption disabled.
  */
 static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
                                 struct pt_regs *regs)
 {
-       int ret = 1; /* Unhandled fault. */
+       int ret = 0;
        u32 dscr;
 
+       /* We must be called with preemption disabled. */
+       WARN_ON(preemptible());
+
        /* We only handle watchpoints and hardware breakpoints. */
        ARM_DBG_READ(c1, 0, dscr);
 
@@ -758,11 +762,15 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
                watchpoint_handler(addr, regs);
                break;
        default:
-               goto out;
+               ret = 1; /* Unhandled fault. */
        }
 
-       ret = 0;
-out:
+       /*
+        * Re-enable preemption after it was disabled in the
+        * low-level exception handling code.
+        */
+       preempt_enable();
+
        return ret;
 }