arm64: mm: Consolidate early page table allocation

The logic for early allocation of page tables is duplicated between
pgd_kernel_pgtable_alloc() and pgd_pgtable_alloc(). Drop the duplication
by calling one from the other and renaming pgd_kernel_pgtable_alloc()
accordingly.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/mm/mmu.c

@@ -371,7 +371,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
 	} while (pgdp++, addr = next, addr != end);
 }
 
-static phys_addr_t pgd_kernel_pgtable_alloc(int shift)
+static phys_addr_t __pgd_pgtable_alloc(int shift)
 {
 	void *ptr = (void *)__get_free_page(PGALLOC_GFP);
 	BUG_ON(!ptr);
@@ -383,8 +383,7 @@ static phys_addr_t pgd_kernel_pgtable_alloc(int shift)
 
 static phys_addr_t pgd_pgtable_alloc(int shift)
 {
-	void *ptr = (void *)__get_free_page(PGALLOC_GFP);
-	BUG_ON(!ptr);
+	phys_addr_t pa = __pgd_pgtable_alloc(shift);
 
 	/*
 	 * Call proper page table ctor in case later we need to
@@ -395,13 +394,11 @@ static phys_addr_t pgd_pgtable_alloc(int shift)
 	 * folded, and if so pgtable_pmd_page_ctor() becomes nop.
 	 */
 	if (shift == PAGE_SHIFT)
-		BUG_ON(!pgtable_page_ctor(virt_to_page(ptr)));
+		BUG_ON(!pgtable_page_ctor(phys_to_page(pa)));
 	else if (shift == PMD_SHIFT)
-		BUG_ON(!pgtable_pmd_page_ctor(virt_to_page(ptr)));
+		BUG_ON(!pgtable_pmd_page_ctor(phys_to_page(pa)));
 
-	/* Ensure the zeroed page is visible to the page table walker */
-	dsb(ishst);
-	return __pa(ptr);
+	return pa;
 }
 
 /*
@@ -605,7 +602,7 @@ static int __init map_entry_trampoline(void)
 	/* Map only the text into the trampoline page table */
 	memset(tramp_pg_dir, 0, PGD_SIZE);
 	__create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
-			     prot, pgd_kernel_pgtable_alloc, 0);
+			     prot, __pgd_pgtable_alloc, 0);
 
 	/* Map both the text and data into the kernel page table */
 	__set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
@@ -1077,8 +1074,7 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
 		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
-			     size, PAGE_KERNEL, pgd_kernel_pgtable_alloc,
-			     flags);
+			     size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);
 
 	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
 			   altmap, want_memblock);