ARM: 8790/1: signal: always use __copy_to_user to save iwmmxt context

When setting a dummy iwmmxt context, create a local instance and
use __copy_to_user both cases whether iwmmxt is being used or not.
This has the benefit of disabling/enabling PAN once for the whole copy
intead of once per write.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 24a78cb..240a30e 100644 (file)
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -77,8 +77,6 @@ static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
                kframe->magic = IWMMXT_MAGIC;
                kframe->size = IWMMXT_STORAGE_SIZE;
                iwmmxt_task_copy(current_thread_info(), &kframe->storage);
-
-               err = __copy_to_user(frame, kframe, sizeof(*frame));
        } else {
                /*
                 * For bug-compatibility with older kernels, some space
@@ -86,10 +84,14 @@ static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
                 * Set the magic and size appropriately so that properly
                 * written userspace can skip it reliably:
                 */
-               __put_user_error(DUMMY_MAGIC, &frame->magic, err);
-               __put_user_error(IWMMXT_STORAGE_SIZE, &frame->size, err);
+               *kframe = (struct iwmmxt_sigframe) {
+                       .magic = DUMMY_MAGIC,
+                       .size  = IWMMXT_STORAGE_SIZE,
+               };
        }
 
+       err = __copy_to_user(frame, kframe, sizeof(*kframe));
+
        return err;
 }