arm64: fix build warning for ARM64_MEMSTART_SHIFT

When building with W=1, the following warning occurs.

arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
  129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
      |                                         ^~~~~~~~~
arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
  142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
      |     ^~~~~~~~~~~~~~~~~~~~

The generic PUD_SHIFT was defined in include/asm-generic/pgtable-nopud.h,
however the #ifndef __ASSEMBLY__ guard in this header file makes it unavailable
for assembly files. While someone .S file include the <asm/kernel-pgtable.h>,
the build warning would occur. Now move the macro ARM64_MEMSTART_SHIFT and
ARM64_MEMSTART_ALIGN to arch/arm64/mm/init.c where it is used only, to avoid
this issue.

Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230804075615.3334756-1-chris.zjh@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Zhang Jianhua

arch/arm64/include/asm/kernel-pgtable.h

@@ -118,31 +118,4 @@
 #define SWAPPER_RX_MMUFLAGS	(SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
 #endif
 
-/*
- * To make optimal use of block mappings when laying out the linear
- * mapping, round down the base of physical memory to a size that can
- * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
- * (64k granule), or a multiple that can be mapped using contiguous bits
- * in the page tables: 32 * PMD_SIZE (16k granule)
- */
-#if defined(CONFIG_ARM64_4K_PAGES)
-#define ARM64_MEMSTART_SHIFT		PUD_SHIFT
-#elif defined(CONFIG_ARM64_16K_PAGES)
-#define ARM64_MEMSTART_SHIFT		CONT_PMD_SHIFT
-#else
-#define ARM64_MEMSTART_SHIFT		PMD_SHIFT
-#endif
-
-/*
- * sparsemem vmemmap imposes an additional requirement on the alignment of
- * memstart_addr, due to the fact that the base of the vmemmap region
- * has a direct correspondence, and needs to appear sufficiently aligned
- * in the virtual address space.
- */
-#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
-#define ARM64_MEMSTART_ALIGN	(1UL << SECTION_SIZE_BITS)
-#else
-#define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
-#endif
-
 #endif	/* __ASM_KERNEL_PGTABLE_H */

arch/arm64/mm/init.c

@@ -73,6 +73,33 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
 
 #define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
 
+/*
+ * To make optimal use of block mappings when laying out the linear
+ * mapping, round down the base of physical memory to a size that can
+ * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE
+ * (64k granule), or a multiple that can be mapped using contiguous bits
+ * in the page tables: 32 * PMD_SIZE (16k granule)
+ */
+#if defined(CONFIG_ARM64_4K_PAGES)
+#define ARM64_MEMSTART_SHIFT		PUD_SHIFT
+#elif defined(CONFIG_ARM64_16K_PAGES)
+#define ARM64_MEMSTART_SHIFT		CONT_PMD_SHIFT
+#else
+#define ARM64_MEMSTART_SHIFT		PMD_SHIFT
+#endif
+
+/*
+ * sparsemem vmemmap imposes an additional requirement on the alignment of
+ * memstart_addr, due to the fact that the base of the vmemmap region
+ * has a direct correspondence, and needs to appear sufficiently aligned
+ * in the virtual address space.
+ */
+#if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
+#define ARM64_MEMSTART_ALIGN	(1UL << SECTION_SIZE_BITS)
+#else
+#define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
+#endif
+
 static int __init reserve_crashkernel_low(unsigned long long low_size)
 {
 	unsigned long long low_base;