xadd() atomically adds a value and returns the previous value. This is needed to implement ticket locks.
This generic arm implementation uses the GCC __sync_fetch_and_add() builtin. This builtin resulted in suitable inlined asm for GCC 4.8.3 (arm64) and GCC 4.6.3 (arm32). Signed-off-by: David Vrabel <david.vra...@citrix.com> Acked-by: Ian Campbell <ian.campb...@citrix.com> --- xen/include/asm-arm/system.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/xen/include/asm-arm/system.h b/xen/include/asm-arm/system.h index ce3d38a..367af1d 100644 --- a/xen/include/asm-arm/system.h +++ b/xen/include/asm-arm/system.h @@ -51,6 +51,8 @@ # error "unknown ARM variant" #endif +#define xadd(x, v) __sync_fetch_and_add(x, v) + extern struct vcpu *__context_switch(struct vcpu *prev, struct vcpu *next); #endif -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
