diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h
index f163d9bb45..60686a3a55 100644
--- a/xen/arch/arm/include/asm/bitops.h
+++ b/xen/arch/arm/include/asm/bitops.h
@@ -22,8 +22,6 @@
 #define __set_bit(n,p)            set_bit(n,p)
 #define __clear_bit(n,p)          clear_bit(n,p)
 
-#define BITS_PER_BYTE           8
-
 #define ADDR (*(volatile int *) addr)
 #define CONST_ADDR (*(const volatile int *) addr)
 
@@ -75,7 +73,7 @@ bool clear_mask16_timeout(uint16_t mask, volatile void *p,
 
 #define arch_ffs(x)  ((x) ? 1 + __builtin_ctz(x) : 0)
 #define arch_ffsl(x) ((x) ? 1 + __builtin_ctzl(x) : 0)
-#define arch_fls(x)  ((x) ? 32 - __builtin_clz(x) : 0)
+#define arch_fls(x)  ((x) ? BITS_PER_INT - __builtin_clz(x) : 0)
 #define arch_flsl(x) ((x) ? BITS_PER_LONG - __builtin_clzl(x) : 0)
 
 #endif /* _ARM_BITOPS_H */
diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h
index 0a51142efd..5a02db6937 100644
--- a/xen/arch/arm/include/asm/config.h
+++ b/xen/arch/arm/include/asm/config.h
@@ -8,19 +8,11 @@
 #define __ARM_CONFIG_H__
 
 #if defined(CONFIG_ARM_64)
-# define LONG_BYTEORDER 3
 # define ELFSIZE 64
 #else
-# define LONG_BYTEORDER 2
 # define ELFSIZE 32
 #endif
 
-#define BYTES_PER_LONG (1 << LONG_BYTEORDER)
-#define BITS_PER_LONG (BYTES_PER_LONG << 3)
-#define POINTER_ALIGN BYTES_PER_LONG
-
-#define BITS_PER_LLONG 64
-
 /* xen_ulong_t is always 64 bits */
 #define BITS_PER_XEN_ULONG 64
 
diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h
index c942e9432e..e72942cca0 100644
--- a/xen/arch/ppc/include/asm/bitops.h
+++ b/xen/arch/ppc/include/asm/bitops.h
@@ -15,8 +15,6 @@
 #define __set_bit(n, p)         set_bit(n, p)
 #define __clear_bit(n, p)       clear_bit(n, p)
 
-#define BITS_PER_BYTE           8
-
 /* PPC bit number conversion */
 #define PPC_BITLSHIFT(be)    (BITS_PER_LONG - 1 - (be))
 #define PPC_BIT(bit)         (1UL << PPC_BITLSHIFT(bit))
@@ -121,7 +119,7 @@ static inline int test_and_set_bit(unsigned int nr, volatile void *addr)
 
 #define arch_ffs(x)  ((x) ? 1 + __builtin_ctz(x) : 0)
 #define arch_ffsl(x) ((x) ? 1 + __builtin_ctzl(x) : 0)
-#define arch_fls(x)  ((x) ? 32 - __builtin_clz(x) : 0)
+#define arch_fls(x)  ((x) ? BITS_PER_INT - __builtin_clz(x) : 0)
 #define arch_flsl(x) ((x) ? BITS_PER_LONG - __builtin_clzl(x) : 0)
 
 #define arch_hweightl(x) __builtin_popcountl(x)
diff --git a/xen/arch/ppc/include/asm/config.h b/xen/arch/ppc/include/asm/config.h
index 148fb3074d..8e32edd5a5 100644
--- a/xen/arch/ppc/include/asm/config.h
+++ b/xen/arch/ppc/include/asm/config.h
@@ -6,19 +6,12 @@
 #include <xen/page-size.h>
 
 #if defined(CONFIG_PPC64)
-#define LONG_BYTEORDER 3
 #define ELFSIZE        64
 #define MAX_VIRT_CPUS  1024u
 #else
 #error "Unsupported PowerPC variant"
 #endif
 
-#define BYTES_PER_LONG (1 << LONG_BYTEORDER)
-#define BITS_PER_LONG  (BYTES_PER_LONG << 3)
-#define POINTER_ALIGN  BYTES_PER_LONG
-
-#define BITS_PER_LLONG 64
-
 /* xen_ulong_t is always 64 bits */
 #define BITS_PER_XEN_ULONG 64
 
diff --git a/xen/arch/riscv/include/asm/config.h b/xen/arch/riscv/include/asm/config.h
index 7141bd9e46..314c97c20a 100644
--- a/xen/arch/riscv/include/asm/config.h
+++ b/xen/arch/riscv/include/asm/config.h
@@ -119,25 +119,12 @@
 #define HYPERVISOR_VIRT_START XEN_VIRT_START
 
 #if defined(CONFIG_RISCV_64)
-# define INT_BYTEORDER 2
-# define LONG_BYTEORDER 3
 # define ELFSIZE 64
 # define MAX_VIRT_CPUS 128u
 #else
 # error "Unsupported RISCV variant"
 #endif
 
-#define BYTES_PER_INT  (1 << INT_BYTEORDER)
-#define BITS_PER_INT  (BYTES_PER_INT << 3)
-
-#define BYTES_PER_LONG (1 << LONG_BYTEORDER)
-#define BITS_PER_LONG  (BYTES_PER_LONG << 3)
-#define POINTER_ALIGN  BYTES_PER_LONG
-
-#define BITS_PER_LLONG 64
-
-#define BITS_PER_BYTE 8
-
 /* xen_ulong_t is always 64 bits */
 #define BITS_PER_XEN_ULONG 64
 
diff --git a/xen/arch/x86/include/asm/config.h b/xen/arch/x86/include/asm/config.h
index 19746f956e..f0123a7de9 100644
--- a/xen/arch/x86/include/asm/config.h
+++ b/xen/arch/x86/include/asm/config.h
@@ -7,16 +7,8 @@
 #ifndef __X86_CONFIG_H__
 #define __X86_CONFIG_H__
 
-#define LONG_BYTEORDER 3
 #define CONFIG_PAGING_LEVELS 4
 
-#define BYTES_PER_LONG (1 << LONG_BYTEORDER)
-#define BITS_PER_LONG (BYTES_PER_LONG << 3)
-#define BITS_PER_BYTE 8
-#define POINTER_ALIGN BYTES_PER_LONG
-
-#define BITS_PER_LLONG 64
-
 #define BITS_PER_XEN_ULONG BITS_PER_LONG
 
 #define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS 1
diff --git a/xen/include/xen/config.h b/xen/include/xen/config.h
index d888b2314d..dbbf2fce62 100644
--- a/xen/include/xen/config.h
+++ b/xen/include/xen/config.h
@@ -98,4 +98,13 @@
 #define ZERO_BLOCK_PTR ((void *)-1L)
 #endif
 
+#define BYTES_PER_LONG  __SIZEOF_LONG__
+
+#define BITS_PER_BYTE   __CHAR_BIT__
+#define BITS_PER_INT    (__SIZEOF_INT__ << 3)
+#define BITS_PER_LONG   (BYTES_PER_LONG << 3)
+#define BITS_PER_LLONG  (__SIZEOF_LONG_LONG__ << 3)
+
+#define POINTER_ALIGN   __SIZEOF_POINTER__
+
 #endif /* __XEN_CONFIG_H__ */
