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Subject[PATCH 4.19 05/85] ARM: 8790/1: signal: always use __copy_to_user to save iwmmxt context
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/kernel/signal.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 76fe75d36312..464393d241e1 100644
--- 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;
}

--
2.19.1


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