x86: some lock annotations for user copy paths, v2

 - introduce might_fault()
 - handle the atomic user copy paths correctly

[ mingo@elte.hu: move might_sleep() outside of in_atomic(). ]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 5 insertions, 15 deletions

diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 8eedde2a9cac..7393152a252e 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -32,9 +32,7 @@ static inline int __movsl_is_ok(unsigned long a1, unsigned long a2, unsigned lon
 #define __do_strncpy_from_user(dst, src, count, res)                       \
 do {                                                                       \
         int __d0, __d1, __d2;                                              \
-        might_sleep();                                                     \
-        if (current->mm)                                                   \
-                might_lock_read(&current->mm->mmap_sem);                   \
+        might_fault();                                                     \
         __asm__ __volatile__(                                              \
                 "       testl %1,%1\n"                                     \
                 "       jz 2f\n"                                           \
@@ -121,9 +119,7 @@ EXPORT_SYMBOL(strncpy_from_user);
 #define __do_clear_user(addr,size)                                      \
 do {                                                                    \
         int __d0;                                                       \
-        might_sleep();                                                  \
-        if (current->mm)                                                \
-                might_lock_read(&current->mm->mmap_sem);                \
+        might_fault();                                                  \
         __asm__ __volatile__(                                           \
                 "0:     rep; stosl\n"                                   \
                 "       movl %2,%0\n"                                   \
@@ -193,9 +189,7 @@ long strnlen_user(const char __user *s, long n)
         unsigned long mask = -__addr_ok(s);
         unsigned long res, tmp;
 
-        might_sleep();
-        if (current->mm)
-                might_lock_read(&current->mm->mmap_sem);
+        might_fault();
 
         __asm__ __volatile__(
                 "       testl %0, %0\n"
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 847d12945998..64d6c84e6353 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -15,9 +15,7 @@
 #define __do_strncpy_from_user(dst,src,count,res)                          \
 do {                                                                       \
         long __d0, __d1, __d2;                                             \
-        might_sleep();                                                     \
-        if (current->mm)                                                   \
-                might_lock_read(&current->mm->mmap_sem);                   \
+        might_fault();                                                     \
         __asm__ __volatile__(                                              \
                 "       testq %1,%1\n"                                     \
                 "       jz 2f\n"                                           \
@@ -66,9 +64,7 @@ EXPORT_SYMBOL(strncpy_from_user);
 unsigned long __clear_user(void __user *addr, unsigned long size)
 {
         long __d0;
-        might_sleep();
-        if (current->mm)
-                might_lock_read(&current->mm->mmap_sem);
+        might_fault();
         /* no memory constraint because it doesn't change any memory gcc knows
            about */
         asm volatile(