ARM: 6864/1: hw_breakpoint: clear DBGVCR out of reset

BugLink: http://bugs.launchpad.net/bugs/769042

commit e89c0d7090c54d7b11b9b091e495a1ae345dd3ff upstream.

The DBGVCR, used for configuring vector catch debug events, is UNKNOWN
out of reset on ARMv7. When enabling monitor mode, this must be zeroed
to avoid UNPREDICTABLE behaviour.

This patch adds the zeroing code to the debug reset path.

Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Leann Ogasawara <leann.ogasawara@canonical.com>

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 44b84fe..7e9a0c7 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -868,6 +868,13 @@ static void reset_ctrl_regs(void *info)
                 */
                asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
                isb();
+
+               /*
+                * Clear any configured vector-catch events before
+                * enabling monitor mode.
+                */
+               asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
+               isb();
        }
 
        if (enable_monitor_mode())