[PATCH] compiler-gcc: disable -ftracer for __noclone functions

From: Paolo Bonzini
Date: Thu Mar 31 2016 - 03:44:21 EST


-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: stable@xxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Reported-by: Linda Walsh <lkml@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
include/linux/compiler-gcc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 22ab246feed3..eeae401a2412 100644
--- 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 */

--
2.5.5