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>

1 files changed, 15 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 1002f473f497..b8fdf4e5e65b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3016,3 +3016,18 @@ void print_vma_addr(char *prefix, unsigned long ip)
         }
         up_read(&current->mm->mmap_sem);
 }
+
+#ifdef CONFIG_PROVE_LOCKING
+void might_fault(void)
+{
+        might_sleep();
+        /*
+         * it would be nicer only to annotate paths which are not under
+         * pagefault_disable, however that requires a larger audit and
+         * providing helpers like get_user_atomic.
+         */
+        if (!in_atomic() && current->mm)
+                might_lock_read(&current->mm->mmap_sem);
+}
+EXPORT_SYMBOL(might_fault);
+#endif