ARM: 7528/1: uaccess: annotate [__]{get,put}_user functions with might_fault()

The user access functions may generate a fault, resulting in invocation
of a handler that may sleep.

This patch annotates the accessors with might_fault() so that we print a
warning if they are invoked from atomic context and help lockdep keep
track of mmap_sem.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 16 insertions, 2 deletions

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 6f83ad6e4d3d..77bd79f2ffdb 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -118,7 +118,7 @@ extern int __get_user_4(void *);
                 : "0" (__p), "r" (__l)                                  \
                 : __GUP_CLOBBER_##__s)
 
-#define get_user(x,p)                                                   \
+#define __get_user_check(x,p)                                                   \
         ({                                                              \
                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
@@ -141,6 +141,12 @@ extern int __get_user_4(void *);
                 __e;                                                    \
         })
 
+#define get_user(x,p)                                                   \
+        ({                                                              \
+                might_fault();                                          \
+                __get_user_check(x,p);                                  \
+         })
+
 extern int __put_user_1(void *, unsigned int);
 extern int __put_user_2(void *, unsigned int);
 extern int __put_user_4(void *, unsigned int);
@@ -155,7 +161,7 @@ extern int __put_user_8(void *, unsigned long long);
                 : "0" (__p), "r" (__r2), "r" (__l)                      \
                 : "ip", "lr", "cc")
 
-#define put_user(x,p)                                                   \
+#define __put_user_check(x,p)                                                   \
         ({                                                              \
                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
@@ -180,6 +186,12 @@ extern int __put_user_8(void *, unsigned long long);
                 __e;                                                    \
         })
 
+#define put_user(x,p)                                                   \
+        ({                                                              \
+                might_fault();                                          \
+                __put_user_check(x,p);                                  \
+         })
+
 #else /* CONFIG_MMU */
 
 /*
@@ -233,6 +245,7 @@ do {									\
         unsigned long __gu_addr = (unsigned long)(ptr);                 \
         unsigned long __gu_val;                                         \
         __chk_user_ptr(ptr);                                            \
+        might_fault();                                                  \
         switch (sizeof(*(ptr))) {                                       \
         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
@@ -314,6 +327,7 @@ do {									\
         unsigned long __pu_addr = (unsigned long)(ptr);                 \
         __typeof__(*(ptr)) __pu_val = (x);                              \
         __chk_user_ptr(ptr);                                            \
+        might_fault();                                                  \
         switch (sizeof(*(ptr))) {                                       \
         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \