[PATCH] guestcopy: evaluate {, __}copy{, _field}_to_guest*() arguments just once

[Jan Beulich <jbeulich@xxxxxxxx>]

There's nothing wrong with having e.g.

    copy_to_guest(uarg, ptr++, 1);

yet until now this would increment "ptr" twice.

Also drop a pair of unneeded parentheses from every instance at this
occasion.

Fixes: b7954cc59831 ("Enhance guest memory accessor macros so that source 
operands can be")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Arm side untested so far, as I don't have all the tool chain pieces
available at home.
---
This goes on top of the assumed v2 of Julien's "xen/guest_access: Harden
copy_to_guest_offset to prevent const dest operand".

--- a/xen/include/asm-arm/guest_access.h
+++ b/xen/include/asm-arm/guest_access.h
@@ -79,7 +79,7 @@ int access_guest_memory_by_ipa(struct do
     const typeof(*(ptr)) *_s = (ptr);                   \
     char (*_d)[sizeof(*_s)] = (void *)(hnd).p;          \
     void *__maybe_unused _t = (hnd).p;                  \
-    ((void)((hnd).p == (ptr)));                         \
+    (void)((hnd).p == _s);                              \
     raw_copy_to_guest(_d+(off), _s, sizeof(*_s)*(nr));  \
 })
 
@@ -106,7 +106,7 @@ int access_guest_memory_by_ipa(struct do
 #define copy_field_to_guest(hnd, ptr, field) ({         \
     const typeof(&(ptr)->field) _s = &(ptr)->field;     \
     void *_d = &(hnd).p->field;                         \
-    ((void)(&(hnd).p->field == &(ptr)->field));         \
+    (void)(&(hnd).p->field == _s);                      \
     raw_copy_to_guest(_d, _s, sizeof(*_s));             \
 })
 
@@ -129,7 +129,7 @@ int access_guest_memory_by_ipa(struct do
     const typeof(*(ptr)) *_s = (ptr);                   \
     char (*_d)[sizeof(*_s)] = (void *)(hnd).p;          \
     void *__maybe_unused _t = (hnd).p;                  \
-    ((void)((hnd).p == (ptr)));                         \
+    (void)((hnd).p == _s);                              \
     __raw_copy_to_guest(_d+(off), _s, sizeof(*_s)*(nr));\
 })
 
@@ -146,7 +146,7 @@ int access_guest_memory_by_ipa(struct do
 #define __copy_field_to_guest(hnd, ptr, field) ({       \
     const typeof(&(ptr)->field) _s = &(ptr)->field;     \
     void *_d = &(hnd).p->field;                         \
-    ((void)(&(hnd).p->field == &(ptr)->field));         \
+    (void)(&(hnd).p->field == _s);                      \
     __raw_copy_to_guest(_d, _s, sizeof(*_s));           \
 })
 
--- a/xen/include/asm-x86/guest_access.h
+++ b/xen/include/asm-x86/guest_access.h
@@ -88,7 +88,7 @@
     const typeof(*(ptr)) *_s = (ptr);                   \
     char (*_d)[sizeof(*_s)] = (void *)(hnd).p;          \
     void *__maybe_unused _t = (hnd).p;                  \
-    ((void)((hnd).p == (ptr)));                         \
+    (void)((hnd).p == _s);                              \
     raw_copy_to_guest(_d+(off), _s, sizeof(*_s)*(nr));  \
 })
 
@@ -111,7 +111,7 @@
 #define copy_field_to_guest(hnd, ptr, field) ({         \
     const typeof(&(ptr)->field) _s = &(ptr)->field;     \
     void *_d = &(hnd).p->field;                         \
-    ((void)(&(hnd).p->field == &(ptr)->field));         \
+    (void)(&(hnd).p->field == _s);                      \
     raw_copy_to_guest(_d, _s, sizeof(*_s));             \
 })
 
@@ -139,7 +139,7 @@
     const typeof(*(ptr)) *_s = (ptr);                   \
     char (*_d)[sizeof(*_s)] = (void *)(hnd).p;          \
     void *__maybe_unused _t = (hnd).p;                  \
-    ((void)((hnd).p == (ptr)));                         \
+    (void)((hnd).p == _s);                              \
     __raw_copy_to_guest(_d+(off), _s, sizeof(*_s)*(nr));\
 })
 
@@ -157,7 +157,7 @@
 #define __copy_field_to_guest(hnd, ptr, field) ({       \
     const typeof(&(ptr)->field) _s = &(ptr)->field;     \
     void *_d = &(hnd).p->field;                         \
-    ((void)(&(hnd).p->field == &(ptr)->field));         \
+    (void)(&(hnd).p->field == _s);                      \
     __raw_copy_to_guest(_d, _s, sizeof(*_s));           \
 })