[4.14,02/17] ARM: 8790/1: signal: always use __copy_to_user to save iwmmxt context

Message ID 20190110175150.5239-3-dave.long@linaro.org
State Superseded
Headers show
Series
  • V4.14 backport of more 32-bit arm spectre patches
Related show

Commit Message

David Long Jan. 10, 2019, 5:51 p.m.
From: Julien Thierry <julien.thierry@arm.com>


Commit 73839798af7ebc6c8d0c9271ebbbc148700e521f upstream.

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>

Signed-off-by: David A. Long <dave.long@linaro.org>

---
 arch/arm/kernel/signal.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

-- 
2.17.1

Patch

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 1dc1f39825b6..b12499cc3582 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -76,8 +76,6 @@  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
@@ -85,10 +83,14 @@  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;
 }