um: adjust current_thread_info() for newer gcc versions

In some cases gcc >= 4.5.2 will optimize away current_thread_info().  To
prevent gcc from doing so the stack address has to be obtained via inline
asm.

Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index e2cf786bda0a..5bd1bad33fab 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -49,7 +49,10 @@ static inline struct thread_info *current_thread_info(void)
 {
         struct thread_info *ti;
         unsigned long mask = THREAD_SIZE - 1;
-        ti = (struct thread_info *) (((unsigned long) &ti) & ~mask);
+        void *p;
+
+        asm volatile ("" : "=r" (p) : "0" (&ti));
+        ti = (struct thread_info *) (((unsigned long)p) & ~mask);
         return ti;
 }