ARM: uaccess: provide uaccess_save_and_enable() and uaccess_restore()
Provide uaccess_save_and_enable() and uaccess_restore() to permit
control of userspace visibility to the kernel, and hook these into
the appropriate places in the kernel where we need to access
userspace.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 5eed828..6795368 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -22,8 +22,11 @@
#ifdef CONFIG_SMP
#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
+({ \
+ unsigned int __ua_flags; \
smp_mb(); \
prefetchw(uaddr); \
+ __ua_flags = uaccess_save_and_enable(); \
__asm__ __volatile__( \
"1: ldrex %1, [%3]\n" \
" " insn "\n" \
@@ -34,12 +37,15 @@
__futex_atomic_ex_table("%5") \
: "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
- : "cc", "memory")
+ : "cc", "memory"); \
+ uaccess_restore(__ua_flags); \
+})
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
+ unsigned int __ua_flags;
int ret;
u32 val;
@@ -49,6 +55,7 @@
smp_mb();
/* Prefetching cannot fault */
prefetchw(uaddr);
+ __ua_flags = uaccess_save_and_enable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
"1: ldrex %1, [%4]\n"
" teq %1, %2\n"
@@ -61,6 +68,7 @@
: "=&r" (ret), "=&r" (val)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
: "cc", "memory");
+ uaccess_restore(__ua_flags);
smp_mb();
*uval = val;
@@ -73,6 +81,8 @@
#include <asm/domain.h>
#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
+({ \
+ unsigned int __ua_flags = uaccess_save_and_enable(); \
__asm__ __volatile__( \
"1: " TUSER(ldr) " %1, [%3]\n" \
" " insn "\n" \
@@ -81,12 +91,15 @@
__futex_atomic_ex_table("%5") \
: "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
- : "cc", "memory")
+ : "cc", "memory"); \
+ uaccess_restore(__ua_flags); \
+})
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
+ unsigned int __ua_flags;
int ret = 0;
u32 val;
@@ -94,6 +107,7 @@
return -EFAULT;
preempt_disable();
+ __ua_flags = uaccess_save_and_enable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
"1: " TUSER(ldr) " %1, [%4]\n"
" teq %1, %2\n"
@@ -103,6 +117,7 @@
: "+r" (ret), "=&r" (val)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
: "cc", "memory");
+ uaccess_restore(__ua_flags);
*uval = val;
preempt_enable();