[PATCH 4.9 06/16] ARM: 8795/1: spectre-v1.1: use put_user() for __put_user()

David Long
2019-02-14T14:49:44Z

From: Julien Thierry <julien.thierry@arm.com>

Commit e3aa6243434fd9a82e84bb79ab1abd14f2d9a5a7 upstream.

When Spectre mitigation is required, __put_user() needs to include
check_uaccess. This is already the case for put_user(), so just make
__put_user() an alias of put_user().

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/include/asm/uaccess.h | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 9ae888775743..b61acd62cffb 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -400,6 +400,14 @@ do { \
__pu_err; \
})

+#ifdef CONFIG_CPU_SPECTRE
+/*
+ * When mitigating Spectre variant 1.1, all accessors need to include
+ * verification of the address space.
+ */
+#define __put_user(x, ptr) put_user(x, ptr)
+
+#else
#define __put_user(x, ptr) \
({ \
long __pu_err = 0; \
@@ -407,12 +415,6 @@ do { \
__pu_err; \
})

-#define __put_user_error(x, ptr, err) \
-({ \
- __put_user_switch((x), (ptr), (err), __put_user_nocheck); \
- (void) 0; \
-})
-
#define __put_user_nocheck(x, __pu_ptr, __err, __size) \
do { \
unsigned long __pu_addr = (unsigned long)__pu_ptr; \
@@ -492,6 +494,7 @@ do { \
: "r" (x), "i" (-EFAULT) \
: "cc")

+#endif /* !CONFIG_CPU_SPECTRE */

#ifdef CONFIG_MMU
extern unsigned long __must_check
--
2.17.1