[PATCH v6 09/16] arm64: uaccess: Add PAN helper

James Morse
2018-01-08T15:38:11Z

Add __uaccess_{en,dis}able_hw_pan() helpers to set/clear the PSTATE.PAN
bit.

Signed-off-by: James Morse <james.morse-5wv7dgnIgG8@public.gmane.org>
---
arch/arm64/include/asm/uaccess.h | 12 ++++++++++++
arch/arm64/kernel/suspend.c | 4 ++--
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 6eadf55ebaf0..3821fab01d7d 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -168,6 +168,18 @@ static inline bool uaccess_ttbr0_enable(void)
}
#endif

+static inline void __uaccess_disable_hw_pan(void)
+{
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,
+ CONFIG_ARM64_PAN));
+}
+
+static inline void __uaccess_enable_hw_pan(void)
+{
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,
+ CONFIG_ARM64_PAN));
+}
+
#define __uaccess_disable(alt) \
do { \
if (!uaccess_ttbr0_disable()) \
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 3fe5ad884418..a307b9e13392 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -2,6 +2,7 @@
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/slab.h>
+#include <linux/uaccess.h>
#include <asm/alternative.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
@@ -51,8 +52,7 @@ void notrace __cpu_suspend_exit(void)
* PSTATE was not saved over suspend/resume, re-enable any detected
* features that might not have been set correctly.
*/
- asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,
- CONFIG_ARM64_PAN));
+ __uaccess_enable_hw_pan();
uao_thread_switch(current);

/*