ARM: 6656/1: hw_breakpoint: avoid UNPREDICTABLE behaviour when reading DBGDSCR

[deliverable/linux.git] / arch / arm / kernel / hw_breakpoint.c

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index c9f3f046757046010ea1f95d13321f676f202d0a..ab02d8aadb77bf05bba6bc3664bf018b988d1a75 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -834,11 +834,11 @@ static void reset_ctrl_regs(void *unused)
 
        /*
         * v7 debug contains save and restore registers so that debug state
-        * can be maintained across low-power modes without leaving
-        * the debug logic powered up. It is IMPLEMENTATION DEFINED whether
-        * we can write to the debug registers out of reset, so we must
-        * unlock the OS Lock Access Register to avoid taking undefined
-        * instruction exceptions later on.
+        * can be maintained across low-power modes without leaving the debug
+        * logic powered up. It is IMPLEMENTATION DEFINED whether we can access
+        * the debug registers out of reset, so we must unlock the OS Lock
+        * Access Register to avoid taking undefined instruction exceptions
+        * later on.
         */
        if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
                /*
@@ -899,18 +899,18 @@ static int __init arch_hw_breakpoint_init(void)
                pr_info("%d breakpoint(s) reserved for watchpoint "
                                "single-step.\n", core_num_reserved_brps);
 
+       /*
+        * Reset the breakpoint resources. We assume that a halting
+        * debugger will leave the world in a nice state for us.
+        */
+       on_each_cpu(reset_ctrl_regs, NULL, 1);
+
        ARM_DBG_READ(c1, 0, dscr);
        if (dscr & ARM_DSCR_HDBGEN) {
+               max_watchpoint_len = 4;
                pr_warning("halting debug mode enabled. Assuming maximum "
-                               "watchpoint size of 4 bytes.");
+                          "watchpoint size of %u bytes.", max_watchpoint_len);
        } else {
-               /*
-                * Reset the breakpoint resources. We assume that a halting
-                * debugger will leave the world in a nice state for us.
-                */
-               smp_call_function(reset_ctrl_regs, NULL, 1);
-               reset_ctrl_regs(NULL);
-
                /* Work out the maximum supported watchpoint length. */
                max_watchpoint_len = get_max_wp_len();
                pr_info("maximum watchpoint size is %u bytes.\n",