arm64: Do not initialise the fixmap page tables in head.S

The early_ioremap_init() function already handles fixmap pte
initialisation, so upgrade this to cover all of pud/pmd/pte and remove
one page from swapper_pg_dir.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Jungseok Lee <jungseoklee85@gmail.com>

arch/arm64/include/asm/page.h

@@ -33,11 +33,11 @@
 
 /*
  * The idmap and swapper page tables need some space reserved in the kernel
- * image. The idmap only requires a pgd and a next level table to (section) map
- * the kernel, while the swapper also maps the FDT and requires an additional
- * table to map an early UART. See __create_page_tables for more information.
+ * image. Both require a pgd and a next level table to (section) map the
+ * kernel. The the swapper also maps the FDT (see __create_page_tables for
+ * more information).
  */
-#define SWAPPER_DIR_SIZE	(3 * PAGE_SIZE)
+#define SWAPPER_DIR_SIZE	(2 * PAGE_SIZE)
 #define IDMAP_DIR_SIZE		(2 * PAGE_SIZE)
 
 #ifndef __ASSEMBLY__

arch/arm64/kernel/head.S

@@ -582,13 +582,6 @@ __create_page_tables:
 	sub	x6, x6, #1			// inclusive range
 	create_block_map x0, x7, x3, x5, x6
 1:
-	/*
-	 * Create the pgd entry for the fixed mappings.
-	 */
-	ldr	x5, =FIXADDR_TOP		// Fixed mapping virtual address
-	add	x0, x26, #2 * PAGE_SIZE		// section table address
-	create_pgd_entry x26, x0, x5, x6, x7
-
 	/*
 	 * Since the page tables have been populated with non-cacheable
 	 * accesses (MMU disabled), invalidate the idmap and swapper page

arch/arm64/mm/ioremap.c

@@ -103,19 +103,25 @@ void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
 }
 EXPORT_SYMBOL(ioremap_cache);
 
-#ifndef CONFIG_ARM64_64K_PAGES
 static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
+#ifndef CONFIG_ARM64_64K_PAGES
+static pte_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss;
 #endif
 
-static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
+static inline pud_t * __init early_ioremap_pud(unsigned long addr)
 {
 	pgd_t *pgd;
-	pud_t *pud;
 
 	pgd = pgd_offset_k(addr);
 	BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd));
 
-	pud = pud_offset(pgd, addr);
+	return pud_offset(pgd, addr);
+}
+
+static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
+{
+	pud_t *pud = early_ioremap_pud(addr);
+
 	BUG_ON(pud_none(*pud) || pud_bad(*pud));
 
 	return pmd_offset(pud, addr);
@@ -132,13 +138,17 @@ static inline pte_t * __init early_ioremap_pte(unsigned long addr)
 
 void __init early_ioremap_init(void)
 {
+	pgd_t *pgd;
+	pud_t *pud;
 	pmd_t *pmd;
+	unsigned long addr = fix_to_virt(FIX_BTMAP_BEGIN);
 
-	pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
-#ifndef CONFIG_ARM64_64K_PAGES
-	/* need to populate pmd for 4k pagesize only */
+	pgd = pgd_offset_k(addr);
+	pud = pud_offset(pgd, addr);
+	pud_populate(&init_mm, pud, bm_pmd);
+	pmd = pmd_offset(pud, addr);
 	pmd_populate_kernel(&init_mm, pmd, bm_pte);
-#endif
+
 	/*
 	 * The boot-ioremap range spans multiple pmds, for which
 	 * we are not prepared: