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From a160443a0d967ea6394cd0d1b7a0ab8ef2da3ff1 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Tue, 29 Mar 2016 15:32:30 +0100
Subject: [PATCH 216/232] copy_from_user: CPU_SW_DOMAIN_PAN compatibility
The downstream copy_from_user acceleration must also play nice with
CONFIG_CPU_SW_DOMAIN_PAN.
See: https://github.com/raspberrypi/linux/issues/1381
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
arch/arm/lib/uaccess_with_memcpy.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/arch/arm/lib/uaccess_with_memcpy.c
+++ b/arch/arm/lib/uaccess_with_memcpy.c
@@ -186,6 +186,7 @@ out:
unsigned long noinline
__copy_from_user_memcpy(void *to, const void __user *from, unsigned long n)
{
+ unsigned long ua_flags;
int atomic;
if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
@@ -217,7 +218,9 @@ __copy_from_user_memcpy(void *to, const
if (tocopy > n)
tocopy = n;
+ ua_flags = uaccess_save_and_enable();
memcpy(to, (const void *)from, tocopy);
+ uaccess_restore(ua_flags);
to += tocopy;
from += tocopy;
n -= tocopy;
@@ -261,9 +264,14 @@ arm_copy_from_user(void *to, const void
* With frame pointer disabled, tail call optimization kicks in
* as well making this test almost invisible.
*/
- if (n < COPY_FROM_USER_THRESHOLD)
- return __copy_from_user_std(to, from, n);
- return __copy_from_user_memcpy(to, from, n);
+ if (n < COPY_TO_USER_THRESHOLD) {
+ unsigned long ua_flags = uaccess_save_and_enable();
+ n = __copy_from_user_std(to, from, n);
+ uaccess_restore(ua_flags);
+ } else {
+ n = __copy_from_user_memcpy(to, from, n);
+ }
+ return n;
}
static unsigned long noinline
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