x86: replace open-coded occurrences of sizeof_field()...

... with macro evaluations, now that it is available.

A recent patch imported the sizeof_field() macro from Linux. This patch makes
use of it in places where the construct is currently open-coded.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/cpu/vpmu_intel.c

@@ -90,8 +90,8 @@ static uint64_t __read_mostly global_ovf_ctrl_mask, global_ctrl_mask;
 static unsigned int __read_mostly regs_sz;
 /* Offset into context of the beginning of PMU register block */
 static const unsigned int regs_off =
-        sizeof(((struct xen_pmu_intel_ctxt *)0)->fixed_counters) +
-        sizeof(((struct xen_pmu_intel_ctxt *)0)->arch_counters);
+    sizeof_field(struct xen_pmu_intel_ctxt, fixed_counters) +
+    sizeof_field(struct xen_pmu_intel_ctxt, arch_counters);
 
 /*
  * QUIRK to workaround an issue on various family 6 cpus.

xen/arch/x86/setup.c

@@ -1617,19 +1617,19 @@ void __init noreturn __start_xen(unsigned long mbi_p)
     total_pages = nr_pages;
 
     /* Sanity check for unwanted bloat of certain hypercall structures. */
-    BUILD_BUG_ON(sizeof(((struct xen_platform_op *)0)->u) !=
-                 sizeof(((struct xen_platform_op *)0)->u.pad));
-    BUILD_BUG_ON(sizeof(((struct xen_domctl *)0)->u) !=
-                 sizeof(((struct xen_domctl *)0)->u.pad));
-    BUILD_BUG_ON(sizeof(((struct xen_sysctl *)0)->u) !=
-                 sizeof(((struct xen_sysctl *)0)->u.pad));
+    BUILD_BUG_ON(sizeof_field(struct xen_platform_op, u) !=
+                 sizeof_field(struct xen_platform_op, u.pad));
+    BUILD_BUG_ON(sizeof_field(struct xen_domctl, u) !=
+                 sizeof_field(struct xen_domctl, u.pad));
+    BUILD_BUG_ON(sizeof_field(struct xen_sysctl, u) !=
+                 sizeof_field(struct xen_sysctl, u.pad));
 
     BUILD_BUG_ON(sizeof(start_info_t) > PAGE_SIZE);
     BUILD_BUG_ON(sizeof(shared_info_t) > PAGE_SIZE);
     BUILD_BUG_ON(sizeof(struct vcpu_info) != 64);
 
-    BUILD_BUG_ON(sizeof(((struct compat_platform_op *)0)->u) !=
-                 sizeof(((struct compat_platform_op *)0)->u.pad));
+    BUILD_BUG_ON(sizeof_field(struct compat_platform_op, u) !=
+                 sizeof_field(struct compat_platform_op, u.pad));
     BUILD_BUG_ON(sizeof(start_info_compat_t) > PAGE_SIZE);
     BUILD_BUG_ON(sizeof(struct compat_vcpu_info) != 64);