Merge tag 'xen-arm64-3.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen into upstream

Introduce Xen support to ARM64

* tag 'xen-arm64-3.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen:
  MAINTAINERS: add myself as arm64/xen maintainer
  arm64/xen: introduce CONFIG_XEN and hypercall.S on ARM64
  arm64/xen: use XEN_IO_PROTO_ABI_ARM on ARM64
  arm64/xen: implement ioremap_cached on arm64
  arm64/xen: introduce asm/xen header files on arm64
  arm/xen: define xen_remap as ioremap_cached

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/sync_bitops.h b/arch/arm64/include/asm/sync_bitops.h
new file mode 100644
index 000000000000..8da0bf4f7659
--- /dev/null
+++ b/arch/arm64/include/asm/sync_bitops.h
@@ -0,0 +1,26 @@
+#ifndef __ASM_SYNC_BITOPS_H__
+#define __ASM_SYNC_BITOPS_H__
+
+#include <asm/bitops.h>
+#include <asm/cmpxchg.h>
+
+/* sync_bitops functions are equivalent to the SMP implementation of the
+ * original functions, independently from CONFIG_SMP being defined.
+ *
+ * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
+ * under Xen you might be communicating with a completely external entity
+ * who might be on another CPU (e.g. two uniprocessor guests communicating
+ * via event channels and grant tables). So we need a variant of the bit
+ * ops which are SMP safe even on a UP kernel.
+ */
+
+#define sync_set_bit(nr, p)            set_bit(nr, p)
+#define sync_clear_bit(nr, p)          clear_bit(nr, p)
+#define sync_change_bit(nr, p)         change_bit(nr, p)
+#define sync_test_and_set_bit(nr, p)   test_and_set_bit(nr, p)
+#define sync_test_and_clear_bit(nr, p) test_and_clear_bit(nr, p)
+#define sync_test_and_change_bit(nr, p)        test_and_change_bit(nr, p)
+#define sync_test_bit(nr, addr)                test_bit(nr, addr)
+#define sync_cmpxchg                   cmpxchg
+
+#endif