[PATCH 4.4 014/137] compiler-gcc: disable -ftracer for __noclone functions

From: Greg Kroah-Hartman
Date: Sun Apr 17 2016 - 22:37:15 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

commit 95272c29378ee7dc15f43fa2758cb28a5913a06d upstream.

-ftracer can duplicate asm blocks causing compilation to fail in
noclone functions. For example, KVM declares a global variable
in an asm like

asm("2: ... \n
.pushsection data \n
.global vmx_return \n
vmx_return: .long 2b");

and -ftracer causes a double declaration.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Reported-by: Linda Walsh <lkml@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

include/linux/compiler-gcc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -199,7 +199,7 @@
#define unreachable() __builtin_unreachable()

/* Mark a function definition as prohibited from being cloned. */
-#define __noclone __attribute__((__noclone__))
+#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))

#endif /* GCC_VERSION >= 40500 */