Enhance guest memory accessor macros so that source operands can be

pointers to const or arrays.

Only build-tested on ia64, and untested for powerpc (which, however,
is almost identical to ia64, except for an apparent bug in the original
version of __copy_field_{from,to}_guest in that the field offset was
multiplied by the field size).

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 23 insertions, 20 deletions

diff --git a/xen/include/xen/xencomm.h b/xen/include/xen/xencomm.h
index e961cc6681..95126ba67f 100644
--- a/xen/include/xen/xencomm.h
+++ b/xen/include/xen/xencomm.h
@@ -47,17 +47,17 @@ static inline unsigned long xencomm_inline_addr(const void *handle)
     ((hnd).p == NULL || xencomm_handle_is_null((hnd).p))
 
 /* Offset the given guest handle into the array it refers to. */
-#define guest_handle_add_offset(hnd, nr) ({         \
-    const typeof((hnd).p) _ptr;                     \
-    xencomm_add_offset((void **)&((hnd).p), nr * sizeof(*_ptr));   \
+#define guest_handle_add_offset(hnd, nr) ({                             \
+    const typeof((hnd).p) _ptr;                                         \
+    xencomm_add_offset((void **)&((hnd).p), nr * sizeof(*_ptr));        \
 })
 
 /* Cast a guest handle to the specified type of handle. */
 #define guest_handle_cast(hnd, type) ({         \
     type *_x = (hnd).p;                         \
-    XEN_GUEST_HANDLE(type) _y; \
-    set_xen_guest_handle(_y, _x); \
-    _y; \
+    XEN_GUEST_HANDLE(type) _y;                  \
+    set_xen_guest_handle(_y, _x);               \
+    _y;                                         \
 })
 
 /* Since we run in real mode, we can safely access all addresses. That also
@@ -87,29 +87,32 @@ static inline unsigned long xencomm_inline_addr(const void *handle)
     __copy_field_from_guest(ptr, hnd, field)
 
 #define __copy_to_guest_offset(hnd, idx, ptr, nr) ({                \
-    const typeof(ptr) _x = (hnd).p;                                 \
-    const typeof(ptr) _y = (ptr);                                   \
-    xencomm_copy_to_guest(_x, _y, sizeof(*_x)*(nr), sizeof(*_x)*(idx)); \
+    const typeof(*(ptr)) *_s = (ptr);                               \
+    void *_d = (hnd).p;                                             \
+    ((void)((hnd).p == (ptr)));                                     \
+    xencomm_copy_to_guest(_d, _s, sizeof(*_s)*(nr), sizeof(*_s)*(idx)); \
 })
 
 #define __copy_field_to_guest(hnd, ptr, field) ({                   \
-    const int _off = offsetof(typeof(*ptr), field);                  \
-    const typeof(&(ptr)->field) _x = &(hnd).p->field;               \
-    const typeof(&(ptr)->field) _y = &(ptr)->field;                 \
-    xencomm_copy_to_guest(_x, _y, sizeof(*_x), sizeof(*_x)*(_off)); \
+    unsigned int _off = offsetof(typeof(*(hnd).p), field);          \
+    const typeof(&(ptr)->field) _s = &(ptr)->field;                 \
+    void *_d = (hnd).p;                                             \
+    ((void)(&(hnd).p->field == &(ptr)->field));                     \
+    xencomm_copy_to_guest(_d, _s, sizeof(*_s), _off);               \
 })
 
 #define __copy_from_guest_offset(ptr, hnd, idx, nr) ({              \
-    const typeof(ptr) _x = (hnd).p;                                 \
-    const typeof(ptr) _y = (ptr);                                   \
-    xencomm_copy_from_guest(_y, _x, sizeof(*_x)*(nr), sizeof(*_x)*(idx));  \
+    const typeof(*(ptr)) *_s = (hnd).p;                             \
+    typeof(*(ptr)) *_d = (ptr);                                     \
+    xencomm_copy_from_guest(_d, _s, sizeof(*_d)*(nr), sizeof(*_d)*(idx)); \
 })
 
 #define __copy_field_from_guest(ptr, hnd, field) ({                 \
-    const int _off = offsetof(typeof(*ptr), field);                 \
-    const typeof(&(ptr)->field) _x = &(hnd).p->field;               \
-    const typeof(&(ptr)->field) _y = &(ptr)->field;                 \
-    xencomm_copy_to_guest(_y, _x, sizeof(*_x), sizeof(*_x)*(_off)); \
+    unsigned int _off = offsetof(typeof(*(hnd).p), field);          \
+    const void *_s = (hnd).p;                                       \
+    typeof(&(ptr)->field) _d = &(ptr)->field;                       \
+    ((void)(&(hnd).p->field == &(ptr)->field));                     \
+    xencomm_copy_from_guest(_d, _s, sizeof(*_d), _off);             \
 })
 
 #endif /* __XENCOMM_H__ */