linux-kernel - [PATCH 4.19 07/17] ARM: 8795/1: spectre-v1.1: use put_user() for __put

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Date:   Wed, 13 Feb 2019 16:32:13 -0500
From:   David Long <dave.long@...aro.org>
To:     stable@...r.kernel.org,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Florian Fainelli <f.fainelli@...il.com>,
        Julien Thierry <julien.thierry@....com>,
        Tony Lindgren <tony@...mide.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     Will Deacon <will.deacon@....com>, Mark Brown <broonie@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4.19 07/17] ARM: 8795/1: spectre-v1.1: use put_user() for __put_user()

From: Julien Thierry <julien.thierry@....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@....com>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: David A. Long <dave.long@...aro.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 d65ef85fc617..1191e7da8fab 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -370,6 +370,14 @@ 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;						\
@@ -377,12 +385,6 @@ 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;	\
@@ -462,6 +464,7 @@ do {									\
 	: "r" (x), "i" (-EFAULT)				\
 	: "cc")
 
+#endif /* !CONFIG_CPU_SPECTRE */
 
 #ifdef CONFIG_MMU
 extern unsigned long __must_check
-- 
2.17.1