x86_64/mm: express macro CNT using ISOLATE_LSB

The various definitions of macro CNT (and the related BUILD_BUG_ON)
can be rewritten using ISOLATE_LSB, encapsulating a violation of
MISRA C:2012 Rule 10.1.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/x86_64/mm.c

@@ -351,9 +351,9 @@ static int setup_compat_m2p_table(struct mem_hotadd_info *info)
                 ~((1UL << (L2_PAGETABLE_SHIFT - 2)) - 1) );
 
 #define MFN(x) (((x) << L2_PAGETABLE_SHIFT) / sizeof(unsigned int))
-#define CNT ((sizeof(*frame_table) & -sizeof(*frame_table)) / \
+#define CNT (ISOLATE_LSB(sizeof(*frame_table)) / \
              sizeof(*compat_machine_to_phys_mapping))
-    BUILD_BUG_ON((sizeof(*frame_table) & -sizeof(*frame_table)) % \
+    BUILD_BUG_ON(ISOLATE_LSB(sizeof(*frame_table)) % \
                  sizeof(*compat_machine_to_phys_mapping));
 
     for ( i = smap; i < emap; i += (1UL << (L2_PAGETABLE_SHIFT - 2)) )
@@ -410,10 +410,10 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
     va = RO_MPT_VIRT_START + smap * sizeof(*machine_to_phys_mapping);
 
 #define MFN(x) (((x) << L2_PAGETABLE_SHIFT) / sizeof(unsigned long))
-#define CNT ((sizeof(*frame_table) & -sizeof(*frame_table)) / \
+#define CNT (ISOLATE_LSB(sizeof(*frame_table)) / \
              sizeof(*machine_to_phys_mapping))
 
-    BUILD_BUG_ON((sizeof(*frame_table) & -sizeof(*frame_table)) % \
+    BUILD_BUG_ON(ISOLATE_LSB(sizeof(*frame_table)) % \
                  sizeof(*machine_to_phys_mapping));
 
     i = smap;
@@ -539,7 +539,7 @@ void __init paging_init(void)
     mpt_size  = (max_page * BYTES_PER_LONG) + (1UL << L2_PAGETABLE_SHIFT) - 1;
     mpt_size &= ~((1UL << L2_PAGETABLE_SHIFT) - 1UL);
 #define MFN(x) (((x) << L2_PAGETABLE_SHIFT) / sizeof(unsigned long))
-#define CNT ((sizeof(*frame_table) & -sizeof(*frame_table)) / \
+#define CNT (ISOLATE_LSB(sizeof(*frame_table)) / \
              sizeof(*machine_to_phys_mapping))
     BUILD_BUG_ON((sizeof(*frame_table) & ~sizeof(*frame_table)) % \
                  sizeof(*machine_to_phys_mapping));
@@ -666,7 +666,7 @@ void __init paging_init(void)
         mpt_size = 0;
 
 #define MFN(x) (((x) << L2_PAGETABLE_SHIFT) / sizeof(unsigned int))
-#define CNT ((sizeof(*frame_table) & -sizeof(*frame_table)) / \
+#define CNT (ISOLATE_LSB(sizeof(*frame_table)) / \
              sizeof(*compat_machine_to_phys_mapping))
     BUILD_BUG_ON((sizeof(*frame_table) & ~sizeof(*frame_table)) % \
                  sizeof(*compat_machine_to_phys_mapping));