arm64: Clear OSDLR_EL1 on CPU boot

commit 6fda41bf12615ee7c3ddac88155099b1a8cf8d00 upstream.

Some firmwares may reboot CPUs with OS Double Lock set. Make sure that
it is unlocked, in order to use debug exceptions.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 06ca574..262925b 100644 (file)
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -135,6 +135,7 @@ NOKPROBE_SYMBOL(disable_debug_monitors);
  */
 static int clear_os_lock(unsigned int cpu)
 {
+       write_sysreg(0, osdlr_el1);
        write_sysreg(0, oslar_el1);
        isb();
        return 0;