[v3,1/7] arm64: Factor out PAN enabling/disabling into separate uaccess_* macros
diff mbox

Message ID 1473788797-10879-2-git-send-email-catalin.marinas@arm.com
State New
Headers show

Commit Message

Catalin Marinas Sept. 13, 2016, 5:46 p.m. UTC
This patch moves the directly coded alternatives for turning PAN on/off
into separate uaccess_{enable,disable} macros or functions. The asm
macros take a few arguments which will be used in subsequent patches.

Note that any (unlikely) access that the compiler might generate between
uaccess_enable() and uaccess_disable(), other than those explicitly
specified by the user access code, will not be protected by PAN.

Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/futex.h       | 14 +++----
 arch/arm64/include/asm/uaccess.h     | 79 ++++++++++++++++++++++++++++++++----
 arch/arm64/kernel/armv8_deprecated.c | 10 ++---
 arch/arm64/lib/clear_user.S          |  8 ++--
 arch/arm64/lib/copy_from_user.S      |  8 ++--
 arch/arm64/lib/copy_in_user.S        |  8 ++--
 arch/arm64/lib/copy_to_user.S        |  8 ++--
 7 files changed, 95 insertions(+), 40 deletions(-)

Comments

Mark Rutland Sept. 15, 2016, 3:10 p.m. UTC | #1
Hi Catalin,

On Tue, Sep 13, 2016 at 06:46:31PM +0100, Catalin Marinas wrote:
> This patch moves the directly coded alternatives for turning PAN on/off
> into separate uaccess_{enable,disable} macros or functions. The asm
> macros take a few arguments which will be used in subsequent patches.
> 
> Note that any (unlikely) access that the compiler might generate between
> uaccess_enable() and uaccess_disable(), other than those explicitly
> specified by the user access code, will not be protected by PAN.

There's one missing include that I've noted below, along with a number
we can now drop. Otherwise, the important parts all look good to me.

With the includes fixed up:

Reviewed-by: Mark Rutland <mark.rutland@arm.com>

[...]

> Cc: Will Deacon <will.deacon@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  arch/arm64/include/asm/futex.h       | 14 +++----
>  arch/arm64/include/asm/uaccess.h     | 79 ++++++++++++++++++++++++++++++++----
>  arch/arm64/kernel/armv8_deprecated.c | 10 ++---
>  arch/arm64/lib/clear_user.S          |  8 ++--
>  arch/arm64/lib/copy_from_user.S      |  8 ++--
>  arch/arm64/lib/copy_in_user.S        |  8 ++--
>  arch/arm64/lib/copy_to_user.S        |  8 ++--
>  7 files changed, 95 insertions(+), 40 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
> index f2585cdd32c2..71dfa3b42313 100644
> --- a/arch/arm64/include/asm/futex.h
> +++ b/arch/arm64/include/asm/futex.h
> @@ -27,9 +27,9 @@
>  #include <asm/sysreg.h>
>  
>  #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)		\
> +do {									\
> +	uaccess_enable();						\
>  	asm volatile(							\
> -	ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,		\
> -		    CONFIG_ARM64_PAN)					\
>  "	prfm	pstl1strm, %2\n"					\
>  "1:	ldxr	%w1, %2\n"						\
>  	insn "\n"							\
> @@ -44,11 +44,11 @@
>  "	.popsection\n"							\
>  	_ASM_EXTABLE(1b, 4b)						\
>  	_ASM_EXTABLE(2b, 4b)						\
> -	ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,		\
> -		    CONFIG_ARM64_PAN)					\
>  	: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)	\
>  	: "r" (oparg), "Ir" (-EFAULT)					\
> -	: "memory")
> +	: "memory");							\
> +	uaccess_disable();						\
> +} while (0)

With the uaccess_{enable,disable}* macros, we can drop the includes for
<asm/alternative.h>, <asm/cpufeature.h>, and <asm/sysreg.h> from
futex.h, as we no longer (directly) use anything from those.

[...]

> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index c47257c91b77..cc6c32d4dcc4 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h

> @@ -321,4 +357,31 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count);
>  extern __must_check long strlen_user(const char __user *str);
>  extern __must_check long strnlen_user(const char __user *str, long n);
>  
> +#else	/* __ASSEMBLY__ */
> +
> +#include <asm/alternative.h>
> +#include <asm/assembler.h>

We also need <asm/sysreg.h> for SET_PSTATE_PAN()

Given we use that and <asm/alternative.h> either way, should we pull
those above the #ifdef __ASSEMBLY__? I have no feeling either way.

[...]

> diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
> index 42ffdb54e162..7156e7bfcd89 100644
> --- a/arch/arm64/kernel/armv8_deprecated.c
> +++ b/arch/arm64/kernel/armv8_deprecated.c
> @@ -281,9 +281,9 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table)
>   * Error-checking SWP macros implemented using ldxr{b}/stxr{b}
>   */
>  #define __user_swpX_asm(data, addr, res, temp, B)		\
> +do {								\
> +	uaccess_enable();					\
>  	__asm__ __volatile__(					\
> -	ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,	\
> -		    CONFIG_ARM64_PAN)				\
>  	"0:	ldxr"B"		%w2, [%3]\n"			\
>  	"1:	stxr"B"		%w0, %w1, [%3]\n"		\
>  	"	cbz		%w0, 2f\n"			\
> @@ -299,11 +299,11 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table)
>  	"	.popsection"					\
>  	_ASM_EXTABLE(0b, 4b)					\
>  	_ASM_EXTABLE(1b, 4b)					\
> -	ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,	\
> -		CONFIG_ARM64_PAN)				\
>  	: "=&r" (res), "+r" (data), "=&r" (temp)		\
>  	: "r" (addr), "i" (-EAGAIN), "i" (-EFAULT)		\
> -	: "memory")
> +	: "memory");						\
> +	uaccess_disable();					\
> +} while (0)

With this, we can drop the include of <asm/alternative.h>, though unlike
futex.h we need to keep <asm/cpufeature.h> and <asm/sysreg.h>.

[...]

> diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
> index 5d1cad3ce6d6..08b5f18ba604 100644
> --- a/arch/arm64/lib/clear_user.S
> +++ b/arch/arm64/lib/clear_user.S
> @@ -17,10 +17,10 @@
>   */
>  #include <linux/linkage.h>
>  
> -#include <asm/alternative.h>
>  #include <asm/assembler.h>
>  #include <asm/cpufeature.h>
>  #include <asm/sysreg.h>
> +#include <asm/uaccess.h>

As with futex.h, we can drop <asm/assembler.h>, <asm/cpufeature.h>, and
<asm/sysreg.h>, as the uaccess_{enable,disable}* macros mean we no
longer use anything from those directly.

[...]

> diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
> index 0b90497d4424..6505ec81f1da 100644
> --- a/arch/arm64/lib/copy_from_user.S
> +++ b/arch/arm64/lib/copy_from_user.S
> @@ -16,11 +16,11 @@
>  
>  #include <linux/linkage.h>
>  
> -#include <asm/alternative.h>
>  #include <asm/assembler.h>
>  #include <asm/cache.h>
>  #include <asm/cpufeature.h>
>  #include <asm/sysreg.h>
> +#include <asm/uaccess.h>

Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and
<asm/sysreg.h> here.

[...]

> diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
> index f7292dd08c84..9b04ff3ab610 100644
> --- a/arch/arm64/lib/copy_in_user.S
> +++ b/arch/arm64/lib/copy_in_user.S
> @@ -18,11 +18,11 @@
>  
>  #include <linux/linkage.h>
>  
> -#include <asm/alternative.h>
>  #include <asm/assembler.h>
>  #include <asm/cache.h>
>  #include <asm/cpufeature.h>
>  #include <asm/sysreg.h>
> +#include <asm/uaccess.h>

Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and
<asm/sysreg.h> here.

[...]

> diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
> index 7a7efe255034..8077e4f34d56 100644
> --- a/arch/arm64/lib/copy_to_user.S
> +++ b/arch/arm64/lib/copy_to_user.S
> @@ -16,11 +16,11 @@
>  
>  #include <linux/linkage.h>
>  
> -#include <asm/alternative.h>
>  #include <asm/assembler.h>
>  #include <asm/cache.h>
>  #include <asm/cpufeature.h>
>  #include <asm/sysreg.h>
> +#include <asm/uaccess.h>

Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and
<asm/sysreg.h> here.

Thanks,
Mark.

Patch
diff mbox

diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
index f2585cdd32c2..71dfa3b42313 100644
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -27,9 +27,9 @@ 
 #include <asm/sysreg.h>
 
 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)		\
+do {									\
+	uaccess_enable();						\
 	asm volatile(							\
-	ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,		\
-		    CONFIG_ARM64_PAN)					\
 "	prfm	pstl1strm, %2\n"					\
 "1:	ldxr	%w1, %2\n"						\
 	insn "\n"							\
@@ -44,11 +44,11 @@ 
 "	.popsection\n"							\
 	_ASM_EXTABLE(1b, 4b)						\
 	_ASM_EXTABLE(2b, 4b)						\
-	ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,		\
-		    CONFIG_ARM64_PAN)					\
 	: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)	\
 	: "r" (oparg), "Ir" (-EFAULT)					\
-	: "memory")
+	: "memory");							\
+	uaccess_disable();						\
+} while (0)
 
 static inline int
 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
@@ -118,8 +118,8 @@  futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 		return -EFAULT;
 
+	uaccess_enable();
 	asm volatile("// futex_atomic_cmpxchg_inatomic\n"
-ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 "	prfm	pstl1strm, %2\n"
 "1:	ldxr	%w1, %2\n"
 "	sub	%w3, %w1, %w4\n"
@@ -134,10 +134,10 @@  ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 "	.popsection\n"
 	_ASM_EXTABLE(1b, 4b)
 	_ASM_EXTABLE(2b, 4b)
-ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 	: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 	: "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 	: "memory");
+	uaccess_disable();
 
 	*uval = val;
 	return ret;
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c91b77..cc6c32d4dcc4 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -18,6 +18,8 @@ 
 #ifndef __ASM_UACCESS_H
 #define __ASM_UACCESS_H
 
+#ifndef __ASSEMBLY__
+
 /*
  * User space memory access functions
  */
@@ -112,6 +114,44 @@  static inline void set_fs(mm_segment_t fs)
 	"	.popsection\n"
 
 /*
+ * User access enabling/disabling.
+ */
+#define __uaccess_disable(alt)						\
+do {									\
+	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt,			\
+			CONFIG_ARM64_PAN));				\
+} while (0)
+
+#define __uaccess_enable(alt)						\
+do {									\
+	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt,			\
+			CONFIG_ARM64_PAN));				\
+} while (0)
+
+static inline void uaccess_disable(void)
+{
+	__uaccess_disable(ARM64_HAS_PAN);
+}
+
+static inline void uaccess_enable(void)
+{
+	__uaccess_enable(ARM64_HAS_PAN);
+}
+
+/*
+ * These functions are no-ops when UAO is present.
+ */
+static inline void uaccess_disable_not_uao(void)
+{
+	__uaccess_disable(ARM64_ALT_PAN_NOT_UAO);
+}
+
+static inline void uaccess_enable_not_uao(void)
+{
+	__uaccess_enable(ARM64_ALT_PAN_NOT_UAO);
+}
+
+/*
  * The "__xxx" versions of the user access functions do not verify the address
  * space - it must have been done previously with a separate "access_ok()"
  * call.
@@ -138,8 +178,7 @@  static inline void set_fs(mm_segment_t fs)
 do {									\
 	unsigned long __gu_val;						\
 	__chk_user_ptr(ptr);						\
-	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
-			CONFIG_ARM64_PAN));				\
+	uaccess_enable_not_uao();					\
 	switch (sizeof(*(ptr))) {					\
 	case 1:								\
 		__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr),  \
@@ -160,9 +199,8 @@  do {									\
 	default:							\
 		BUILD_BUG();						\
 	}								\
+	uaccess_disable_not_uao();					\
 	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
-	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
-			CONFIG_ARM64_PAN));				\
 } while (0)
 
 #define __get_user(x, ptr)						\
@@ -207,8 +245,7 @@  do {									\
 do {									\
 	__typeof__(*(ptr)) __pu_val = (x);				\
 	__chk_user_ptr(ptr);						\
-	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
-			CONFIG_ARM64_PAN));				\
+	uaccess_enable_not_uao();					\
 	switch (sizeof(*(ptr))) {					\
 	case 1:								\
 		__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr),	\
@@ -229,8 +266,7 @@  do {									\
 	default:							\
 		BUILD_BUG();						\
 	}								\
-	asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
-			CONFIG_ARM64_PAN));				\
+	uaccess_disable_not_uao();					\
 } while (0)
 
 #define __put_user(x, ptr)						\
@@ -321,4 +357,31 @@  extern long strncpy_from_user(char *dest, const char __user *src, long count);
 extern __must_check long strlen_user(const char __user *str);
 extern __must_check long strnlen_user(const char __user *str, long n);
 
+#else	/* __ASSEMBLY__ */
+
+#include <asm/alternative.h>
+#include <asm/assembler.h>
+
+/*
+ * User access enabling/disabling macros. These are no-ops when UAO is
+ * present.
+ */
+	.macro	uaccess_disable_not_uao, tmp1
+alternative_if_not ARM64_ALT_PAN_NOT_UAO
+	nop
+alternative_else
+	SET_PSTATE_PAN(1)
+alternative_endif
+	.endm
+
+	.macro	uaccess_enable_not_uao, tmp1, tmp2
+alternative_if_not ARM64_ALT_PAN_NOT_UAO
+	nop
+alternative_else
+	SET_PSTATE_PAN(0)
+alternative_endif
+	.endm
+
+#endif	/* __ASSEMBLY__ */
+
 #endif /* __ASM_UACCESS_H */
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index 42ffdb54e162..7156e7bfcd89 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -281,9 +281,9 @@  static void __init register_insn_emulation_sysctl(struct ctl_table *table)
  * Error-checking SWP macros implemented using ldxr{b}/stxr{b}
  */
 #define __user_swpX_asm(data, addr, res, temp, B)		\
+do {								\
+	uaccess_enable();					\
 	__asm__ __volatile__(					\
-	ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,	\
-		    CONFIG_ARM64_PAN)				\
 	"0:	ldxr"B"		%w2, [%3]\n"			\
 	"1:	stxr"B"		%w0, %w1, [%3]\n"		\
 	"	cbz		%w0, 2f\n"			\
@@ -299,11 +299,11 @@  static void __init register_insn_emulation_sysctl(struct ctl_table *table)
 	"	.popsection"					\
 	_ASM_EXTABLE(0b, 4b)					\
 	_ASM_EXTABLE(1b, 4b)					\
-	ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,	\
-		CONFIG_ARM64_PAN)				\
 	: "=&r" (res), "+r" (data), "=&r" (temp)		\
 	: "r" (addr), "i" (-EAGAIN), "i" (-EFAULT)		\
-	: "memory")
+	: "memory");						\
+	uaccess_disable();					\
+} while (0)
 
 #define __user_swp_asm(data, addr, res, temp) \
 	__user_swpX_asm(data, addr, res, temp, "")
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index 5d1cad3ce6d6..08b5f18ba604 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -17,10 +17,10 @@ 
  */
 #include <linux/linkage.h>
 
-#include <asm/alternative.h>
 #include <asm/assembler.h>
 #include <asm/cpufeature.h>
 #include <asm/sysreg.h>
+#include <asm/uaccess.h>
 
 	.text
 
@@ -33,8 +33,7 @@ 
  * Alignment fixed up by hardware.
  */
 ENTRY(__clear_user)
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_enable_not_uao x2, x3
 	mov	x2, x1			// save the size for fixup return
 	subs	x1, x1, #8
 	b.mi	2f
@@ -54,8 +53,7 @@  uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
 	b.mi	5f
 uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
 5:	mov	x0, #0
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_disable_not_uao x2
 	ret
 ENDPROC(__clear_user)
 
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 0b90497d4424..6505ec81f1da 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -16,11 +16,11 @@ 
 
 #include <linux/linkage.h>
 
-#include <asm/alternative.h>
 #include <asm/assembler.h>
 #include <asm/cache.h>
 #include <asm/cpufeature.h>
 #include <asm/sysreg.h>
+#include <asm/uaccess.h>
 
 /*
  * Copy from user space to a kernel buffer (alignment handled by the hardware)
@@ -67,12 +67,10 @@ 
 
 end	.req	x5
 ENTRY(__arch_copy_from_user)
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_enable_not_uao x3, x4
 	add	end, x0, x2
 #include "copy_template.S"
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_disable_not_uao x3
 	mov	x0, #0				// Nothing to copy
 	ret
 ENDPROC(__arch_copy_from_user)
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
index f7292dd08c84..9b04ff3ab610 100644
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -18,11 +18,11 @@ 
 
 #include <linux/linkage.h>
 
-#include <asm/alternative.h>
 #include <asm/assembler.h>
 #include <asm/cache.h>
 #include <asm/cpufeature.h>
 #include <asm/sysreg.h>
+#include <asm/uaccess.h>
 
 /*
  * Copy from user space to user space (alignment handled by the hardware)
@@ -68,12 +68,10 @@ 
 
 end	.req	x5
 ENTRY(__copy_in_user)
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_enable_not_uao x3, x4
 	add	end, x0, x2
 #include "copy_template.S"
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_disable_not_uao x3
 	mov	x0, #0
 	ret
 ENDPROC(__copy_in_user)
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 7a7efe255034..8077e4f34d56 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -16,11 +16,11 @@ 
 
 #include <linux/linkage.h>
 
-#include <asm/alternative.h>
 #include <asm/assembler.h>
 #include <asm/cache.h>
 #include <asm/cpufeature.h>
 #include <asm/sysreg.h>
+#include <asm/uaccess.h>
 
 /*
  * Copy to user space from a kernel buffer (alignment handled by the hardware)
@@ -66,12 +66,10 @@ 
 
 end	.req	x5
 ENTRY(__arch_copy_to_user)
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_enable_not_uao x3, x4
 	add	end, x0, x2
 #include "copy_template.S"
-ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
-	    CONFIG_ARM64_PAN)
+	uaccess_disable_not_uao x3
 	mov	x0, #0
 	ret
 ENDPROC(__arch_copy_to_user)