1 files changed, 336 insertions, 196 deletions

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 58faeaa7f..f3e5c7423 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -30,8 +30,10 @@
 #include <linux/slab.h>
 #include <linux/stop_machine.h>
 
+#include <asm/barrier.h>
 #include <asm/cputype.h>
 #include <asm/fixmap.h>
+#include <asm/kasan.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
@@ -44,13 +46,20 @@
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 
+u64 kimage_voffset __read_mostly;
+EXPORT_SYMBOL(kimage_voffset);
+
 /*
  * Empty_zero_page is a special page that is used for zero-initialized data
  * and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
+static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
+static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
+static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
+
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 			      unsigned long size, pgprot_t vma_prot)
 {
@@ -62,16 +71,30 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 }
 EXPORT_SYMBOL(phys_mem_access_prot);
 
-static void __init *early_alloc(unsigned long sz)
+static phys_addr_t __init early_pgtable_alloc(void)
 {
 	phys_addr_t phys;
 	void *ptr;
 
-	phys = memblock_alloc(sz, sz);
+	phys = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 	BUG_ON(!phys);
-	ptr = __va(phys);
-	memset(ptr, 0, sz);
-	return ptr;
+
+	/*
+	 * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE
+	 * slot will be free, so we can (ab)use the FIX_PTE slot to initialise
+	 * any level of table.
+	 */
+	ptr = pte_set_fixmap(phys);
+
+	memset(ptr, 0, PAGE_SIZE);
+
+	/*
+	 * Implicit barriers also ensure the zeroed page is visible to the page
+	 * table walker
+	 */
+	pte_clear_fixmap();
+
+	return phys;
 }
 
 /*
@@ -95,24 +118,30 @@ static void split_pmd(pmd_t *pmd, pte_t *pte)
 static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, unsigned long pfn,
 				  pgprot_t prot,
-				  void *(*alloc)(unsigned long size))
+				  phys_addr_t (*pgtable_alloc)(void))
 {
 	pte_t *pte;
 
 	if (pmd_none(*pmd) || pmd_sect(*pmd)) {
-		pte = alloc(PTRS_PER_PTE * sizeof(pte_t));
+		phys_addr_t pte_phys;
+		BUG_ON(!pgtable_alloc);
+		pte_phys = pgtable_alloc();
+		pte = pte_set_fixmap(pte_phys);
 		if (pmd_sect(*pmd))
 			split_pmd(pmd, pte);
-		__pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE);
+		__pmd_populate(pmd, pte_phys, PMD_TYPE_TABLE);
 		flush_tlb_all();
+		pte_clear_fixmap();
 	}
 	BUG_ON(pmd_bad(*pmd));
 
-	pte = pte_offset_kernel(pmd, addr);
+	pte = pte_set_fixmap_offset(pmd, addr);
 	do {
 		set_pte(pte, pfn_pte(pfn, prot));
 		pfn++;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
+
+	pte_clear_fixmap();
 }
 
 static void split_pud(pud_t *old_pud, pmd_t *pmd)
@@ -127,10 +156,29 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
 	} while (pmd++, i++, i < PTRS_PER_PMD);
 }
 
-static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
-				  unsigned long addr, unsigned long end,
+#ifdef CONFIG_DEBUG_PAGEALLOC
+static bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
+{
+
+	/*
+	 * If debug_page_alloc is enabled we must map the linear map
+	 * using pages. However, other mappings created by
+	 * create_mapping_noalloc must use sections in some cases. Allow
+	 * sections to be used in those cases, where no pgtable_alloc
+	 * function is provided.
+	 */
+	return !pgtable_alloc || !debug_pagealloc_enabled();
+}
+#else
+static bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
+{
+	return true;
+}
+#endif
+
+static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 				  phys_addr_t phys, pgprot_t prot,
-				  void *(*alloc)(unsigned long size))
+				  phys_addr_t (*pgtable_alloc)(void))
 {
 	pmd_t *pmd;
 	unsigned long next;
@@ -139,7 +187,10 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
 	 * Check for initial section mappings in the pgd/pud and remove them.
 	 */
 	if (pud_none(*pud) || pud_sect(*pud)) {
-		pmd = alloc(PTRS_PER_PMD * sizeof(pmd_t));
+		phys_addr_t pmd_phys;
+		BUG_ON(!pgtable_alloc);
+		pmd_phys = pgtable_alloc();
+		pmd = pmd_set_fixmap(pmd_phys);
 		if (pud_sect(*pud)) {
 			/*
 			 * need to have the 1G of mappings continue to be
@@ -147,19 +198,20 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
 			 */
 			split_pud(pud, pmd);
 		}
-		pud_populate(mm, pud, pmd);
+		__pud_populate(pud, pmd_phys, PUD_TYPE_TABLE);
 		flush_tlb_all();
+		pmd_clear_fixmap();
 	}
 	BUG_ON(pud_bad(*pud));
 
-	pmd = pmd_offset(pud, addr);
+	pmd = pmd_set_fixmap_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
 		/* try section mapping first */
-		if (((addr | next | phys) & ~SECTION_MASK) == 0) {
+		if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
+		      block_mappings_allowed(pgtable_alloc)) {
 			pmd_t old_pmd =*pmd;
-			set_pmd(pmd, __pmd(phys |
-					   pgprot_val(mk_sect_prot(prot))));
+			pmd_set_huge(pmd, phys, prot);
 			/*
 			 * Check for previous table entries created during
 			 * boot (__create_page_tables) and flush them.
@@ -167,17 +219,19 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
 			if (!pmd_none(old_pmd)) {
 				flush_tlb_all();
 				if (pmd_table(old_pmd)) {
-					phys_addr_t table = __pa(pte_offset_map(&old_pmd, 0));
+					phys_addr_t table = pmd_page_paddr(old_pmd);
 					if (!WARN_ON_ONCE(slab_is_available()))
 						memblock_free(table, PAGE_SIZE);
 				}
 			}
 		} else {
 			alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
-				       prot, alloc);
+				       prot, pgtable_alloc);
 		}
 		phys += next - addr;
 	} while (pmd++, addr = next, addr != end);
+
+	pmd_clear_fixmap();
 }
 
 static inline bool use_1G_block(unsigned long addr, unsigned long next,
@@ -192,31 +246,32 @@ static inline bool use_1G_block(unsigned long addr, unsigned long next,
 	return true;
 }
 
-static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
-				  unsigned long addr, unsigned long end,
+static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
 				  phys_addr_t phys, pgprot_t prot,
-				  void *(*alloc)(unsigned long size))
+				  phys_addr_t (*pgtable_alloc)(void))
 {
 	pud_t *pud;
 	unsigned long next;
 
 	if (pgd_none(*pgd)) {
-		pud = alloc(PTRS_PER_PUD * sizeof(pud_t));
-		pgd_populate(mm, pgd, pud);
+		phys_addr_t pud_phys;
+		BUG_ON(!pgtable_alloc);
+		pud_phys = pgtable_alloc();
+		__pgd_populate(pgd, pud_phys, PUD_TYPE_TABLE);
 	}
 	BUG_ON(pgd_bad(*pgd));
 
-	pud = pud_offset(pgd, addr);
+	pud = pud_set_fixmap_offset(pgd, addr);
 	do {
 		next = pud_addr_end(addr, end);
 
 		/*
 		 * For 4K granule only, attempt to put down a 1GB block
 		 */
-		if (use_1G_block(addr, next, phys)) {
+		if (use_1G_block(addr, next, phys) &&
+		    block_mappings_allowed(pgtable_alloc)) {
 			pud_t old_pud = *pud;
-			set_pud(pud, __pud(phys |
-					   pgprot_val(mk_sect_prot(prot))));
+			pud_set_huge(pud, phys, prot);
 
 			/*
 			 * If we have an old value for a pud, it will
@@ -228,26 +283,28 @@ static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
 			if (!pud_none(old_pud)) {
 				flush_tlb_all();
 				if (pud_table(old_pud)) {
-					phys_addr_t table = __pa(pmd_offset(&old_pud, 0));
+					phys_addr_t table = pud_page_paddr(old_pud);
 					if (!WARN_ON_ONCE(slab_is_available()))
 						memblock_free(table, PAGE_SIZE);
 				}
 			}
 		} else {
-			alloc_init_pmd(mm, pud, addr, next, phys, prot, alloc);
+			alloc_init_pmd(pud, addr, next, phys, prot,
+				       pgtable_alloc);
 		}
 		phys += next - addr;
 	} while (pud++, addr = next, addr != end);
+
+	pud_clear_fixmap();
 }
 
 /*
  * Create the page directory entries and any necessary page tables for the
  * mapping specified by 'md'.
  */
-static void  __create_mapping(struct mm_struct *mm, pgd_t *pgd,
-				    phys_addr_t phys, unsigned long virt,
+static void init_pgd(pgd_t *pgd, phys_addr_t phys, unsigned long virt,
 				    phys_addr_t size, pgprot_t prot,
-				    void *(*alloc)(unsigned long size))
+				    phys_addr_t (*pgtable_alloc)(void))
 {
 	unsigned long addr, length, end, next;
 
@@ -265,22 +322,35 @@ static void  __create_mapping(struct mm_struct *mm, pgd_t *pgd,
 	end = addr + length;
 	do {
 		next = pgd_addr_end(addr, end);
-		alloc_init_pud(mm, pgd, addr, next, phys, prot, alloc);
+		alloc_init_pud(pgd, addr, next, phys, prot, pgtable_alloc);
 		phys += next - addr;
 	} while (pgd++, addr = next, addr != end);
 }
 
-static void *late_alloc(unsigned long size)
+static phys_addr_t late_pgtable_alloc(void)
 {
-	void *ptr;
-
-	BUG_ON(size > PAGE_SIZE);
-	ptr = (void *)__get_free_page(PGALLOC_GFP);
+	void *ptr = (void *)__get_free_page(PGALLOC_GFP);
 	BUG_ON(!ptr);
-	return ptr;
+
+	/* Ensure the zeroed page is visible to the page table walker */
+	dsb(ishst);
+	return __pa(ptr);
 }
 
-static void __init create_mapping(phys_addr_t phys, unsigned long virt,
+static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
+				 unsigned long virt, phys_addr_t size,
+				 pgprot_t prot,
+				 phys_addr_t (*alloc)(void))
+{
+	init_pgd(pgd_offset_raw(pgdir, virt), phys, virt, size, prot, alloc);
+}
+
+/*
+ * This function can only be used to modify existing table entries,
+ * without allocating new levels of table. Note that this permits the
+ * creation of new section or page entries.
+ */
+static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
 				  phys_addr_t size, pgprot_t prot)
 {
 	if (virt < VMALLOC_START) {
@@ -288,16 +358,16 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
 			&phys, virt);
 		return;
 	}
-	__create_mapping(&init_mm, pgd_offset_k(virt), phys, virt,
-			 size, prot, early_alloc);
+	__create_pgd_mapping(init_mm.pgd, phys, virt, size, prot,
+			     NULL);
 }
 
 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       unsigned long virt, phys_addr_t size,
 			       pgprot_t prot)
 {
-	__create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot,
-				late_alloc);
+	__create_pgd_mapping(mm->pgd, phys, virt, size, prot,
+			     late_pgtable_alloc);
 }
 
 static void create_mapping_late(phys_addr_t phys, unsigned long virt,
@@ -309,69 +379,57 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
 		return;
 	}
 
-	return __create_mapping(&init_mm, pgd_offset_k(virt),
-				phys, virt, size, prot, late_alloc);
+	__create_pgd_mapping(init_mm.pgd, phys, virt, size, prot,
+			     late_pgtable_alloc);
 }
 
-#ifdef CONFIG_DEBUG_RODATA
-static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
+static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
 {
+	unsigned long kernel_start = __pa(_stext);
+	unsigned long kernel_end = __pa(_etext);
+
 	/*
-	 * Set up the executable regions using the existing section mappings
-	 * for now. This will get more fine grained later once all memory
-	 * is mapped
+	 * Take care not to create a writable alias for the
+	 * read-only text and rodata sections of the kernel image.
 	 */
-	unsigned long kernel_x_start = round_down(__pa(_stext), SWAPPER_BLOCK_SIZE);
-	unsigned long kernel_x_end = round_up(__pa(__init_end), SWAPPER_BLOCK_SIZE);
-
-	if (end < kernel_x_start) {
-		create_mapping(start, __phys_to_virt(start),
-			end - start, PAGE_KERNEL);
-	} else if (start >= kernel_x_end) {
-		create_mapping(start, __phys_to_virt(start),
-			end - start, PAGE_KERNEL);
-	} else {
-		if (start < kernel_x_start)
-			create_mapping(start, __phys_to_virt(start),
-				kernel_x_start - start,
-				PAGE_KERNEL);
-		create_mapping(kernel_x_start,
-				__phys_to_virt(kernel_x_start),
-				kernel_x_end - kernel_x_start,
-				PAGE_KERNEL_EXEC);
-		if (kernel_x_end < end)
-			create_mapping(kernel_x_end,
-				__phys_to_virt(kernel_x_end),
-				end - kernel_x_end,
-				PAGE_KERNEL);
+
+	/* No overlap with the kernel text */
+	if (end < kernel_start || start >= kernel_end) {
+		__create_pgd_mapping(pgd, start, __phys_to_virt(start),
+				     end - start, PAGE_KERNEL,
+				     early_pgtable_alloc);
+		return;
 	}
 
+	/*
+	 * This block overlaps the kernel text mapping.
+	 * Map the portion(s) which don't overlap.
+	 */
+	if (start < kernel_start)
+		__create_pgd_mapping(pgd, start,
+				     __phys_to_virt(start),
+				     kernel_start - start, PAGE_KERNEL,
+				     early_pgtable_alloc);
+	if (kernel_end < end)
+		__create_pgd_mapping(pgd, kernel_end,
+				     __phys_to_virt(kernel_end),
+				     end - kernel_end, PAGE_KERNEL,
+				     early_pgtable_alloc);
+
+	/*
+	 * Map the linear alias of the [_stext, _etext) interval as
+	 * read-only/non-executable. This makes the contents of the
+	 * region accessible to subsystems such as hibernate, but
+	 * protects it from inadvertent modification or execution.
+	 */
+	__create_pgd_mapping(pgd, kernel_start, __phys_to_virt(kernel_start),
+			     kernel_end - kernel_start, PAGE_KERNEL_RO,
+			     early_pgtable_alloc);
 }
-#else
-static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
-{
-	create_mapping(start, __phys_to_virt(start), end - start,
-			PAGE_KERNEL_EXEC);
-}
-#endif
 
-static void __init map_mem(void)
+static void __init map_mem(pgd_t *pgd)
 {
 	struct memblock_region *reg;
-	phys_addr_t limit;
-
-	/*
-	 * Temporarily limit the memblock range. We need to do this as
-	 * create_mapping requires puds, pmds and ptes to be allocated from
-	 * memory addressable from the initial direct kernel mapping.
-	 *
-	 * The initial direct kernel mapping, located at swapper_pg_dir, gives
-	 * us PUD_SIZE (with SECTION maps) or PMD_SIZE (without SECTION maps,
-	 * memory starting from PHYS_OFFSET (which must be aligned to 2MB as
-	 * per Documentation/arm64/booting.txt).
-	 */
-	limit = PHYS_OFFSET + SWAPPER_INIT_MAP_SIZE;
-	memblock_set_current_limit(limit);
 
 	/* map all the memory banks */
 	for_each_memblock(memory, reg) {
@@ -383,69 +441,94 @@ static void __init map_mem(void)
 		if (memblock_is_nomap(reg))
 			continue;
 
-		if (ARM64_SWAPPER_USES_SECTION_MAPS) {
-			/*
-			 * For the first memory bank align the start address and
-			 * current memblock limit to prevent create_mapping() from
-			 * allocating pte page tables from unmapped memory. With
-			 * the section maps, if the first block doesn't end on section
-			 * size boundary, create_mapping() will try to allocate a pte
-			 * page, which may be returned from an unmapped area.
-			 * When section maps are not used, the pte page table for the
-			 * current limit is already present in swapper_pg_dir.
-			 */
-			if (start < limit)
-				start = ALIGN(start, SECTION_SIZE);
-			if (end < limit) {
-				limit = end & SECTION_MASK;
-				memblock_set_current_limit(limit);
-			}
-		}
-		__map_memblock(start, end);
+		__map_memblock(pgd, start, end);
 	}
-
-	/* Limit no longer required. */
-	memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
 }
 
-static void __init fixup_executable(void)
+void mark_rodata_ro(void)
 {
-#ifdef CONFIG_DEBUG_RODATA
-	/* now that we are actually fully mapped, make the start/end more fine grained */
-	if (!IS_ALIGNED((unsigned long)_stext, SWAPPER_BLOCK_SIZE)) {
-		unsigned long aligned_start = round_down(__pa(_stext),
-							 SWAPPER_BLOCK_SIZE);
+	unsigned long section_size;
 
-		create_mapping(aligned_start, __phys_to_virt(aligned_start),
-				__pa(_stext) - aligned_start,
-				PAGE_KERNEL);
-	}
+	section_size = (unsigned long)__start_rodata - (unsigned long)_stext;
+	create_mapping_late(__pa(_stext), (unsigned long)_stext,
+			    section_size, PAGE_KERNEL_ROX);
+	/*
+	 * mark .rodata as read only. Use _etext rather than __end_rodata to
+	 * cover NOTES and EXCEPTION_TABLE.
+	 */
+	section_size = (unsigned long)_etext - (unsigned long)__start_rodata;
+	create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
+			    section_size, PAGE_KERNEL_RO);
+}
 
-	if (!IS_ALIGNED((unsigned long)__init_end, SWAPPER_BLOCK_SIZE)) {
-		unsigned long aligned_end = round_up(__pa(__init_end),
-							  SWAPPER_BLOCK_SIZE);
-		create_mapping(__pa(__init_end), (unsigned long)__init_end,
-				aligned_end - __pa(__init_end),
-				PAGE_KERNEL);
-	}
-#endif
+void fixup_init(void)
+{
+	/*
+	 * Unmap the __init region but leave the VM area in place. This
+	 * prevents the region from being reused for kernel modules, which
+	 * is not supported by kallsyms.
+	 */
+	unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
 }
 
-#ifdef CONFIG_DEBUG_RODATA
-void mark_rodata_ro(void)
+static void __init map_kernel_chunk(pgd_t *pgd, void *va_start, void *va_end,
+				    pgprot_t prot, struct vm_struct *vma)
 {
-	create_mapping_late(__pa(_stext), (unsigned long)_stext,
-				(unsigned long)_etext - (unsigned long)_stext,
-				PAGE_KERNEL_ROX);
+	phys_addr_t pa_start = __pa(va_start);
+	unsigned long size = va_end - va_start;
+
+	BUG_ON(!PAGE_ALIGNED(pa_start));
+	BUG_ON(!PAGE_ALIGNED(size));
+
+	__create_pgd_mapping(pgd, pa_start, (unsigned long)va_start, size, prot,
+			     early_pgtable_alloc);
+
+	vma->addr	= va_start;
+	vma->phys_addr	= pa_start;
+	vma->size	= size;
+	vma->flags	= VM_MAP;
+	vma->caller	= __builtin_return_address(0);
 
+	vm_area_add_early(vma);
 }
-#endif
 
-void fixup_init(void)
+/*
+ * Create fine-grained mappings for the kernel.
+ */
+static void __init map_kernel(pgd_t *pgd)
 {
-	create_mapping_late(__pa(__init_begin), (unsigned long)__init_begin,
-			(unsigned long)__init_end - (unsigned long)__init_begin,
-			PAGE_KERNEL);
+	static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
+
+	map_kernel_chunk(pgd, _stext, __start_rodata, PAGE_KERNEL_EXEC, &vmlinux_text);
+	map_kernel_chunk(pgd, __start_rodata, _etext, PAGE_KERNEL, &vmlinux_rodata);
+	map_kernel_chunk(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC,
+			 &vmlinux_init);
+	map_kernel_chunk(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data);
+
+	if (!pgd_val(*pgd_offset_raw(pgd, FIXADDR_START))) {
+		/*
+		 * The fixmap falls in a separate pgd to the kernel, and doesn't
+		 * live in the carveout for the swapper_pg_dir. We can simply
+		 * re-use the existing dir for the fixmap.
+		 */
+		set_pgd(pgd_offset_raw(pgd, FIXADDR_START),
+			*pgd_offset_k(FIXADDR_START));
+	} else if (CONFIG_PGTABLE_LEVELS > 3) {
+		/*
+		 * The fixmap shares its top level pgd entry with the kernel
+		 * mapping. This can really only occur when we are running
+		 * with 16k/4 levels, so we can simply reuse the pud level
+		 * entry instead.
+		 */
+		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
+		set_pud(pud_set_fixmap_offset(pgd, FIXADDR_START),
+			__pud(__pa(bm_pmd) | PUD_TYPE_TABLE));
+		pud_clear_fixmap();
+	} else {
+		BUG();
+	}
+
+	kasan_copy_shadow(pgd);
 }
 
 /*
@@ -454,28 +537,35 @@ void fixup_init(void)
  */
 void __init paging_init(void)
 {
-	void *zero_page;
+	phys_addr_t pgd_phys = early_pgtable_alloc();
+	pgd_t *pgd = pgd_set_fixmap(pgd_phys);
 
-	map_mem();
-	fixup_executable();
+	map_kernel(pgd);
+	map_mem(pgd);
 
-	/* allocate the zero page. */
-	zero_page = early_alloc(PAGE_SIZE);
-
-	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
+	/*
+	 * We want to reuse the original swapper_pg_dir so we don't have to
+	 * communicate the new address to non-coherent secondaries in
+	 * secondary_entry, and so cpu_switch_mm can generate the address with
+	 * adrp+add rather than a load from some global variable.
+	 *
+	 * To do this we need to go via a temporary pgd.
+	 */
+	cpu_replace_ttbr1(__va(pgd_phys));
+	memcpy(swapper_pg_dir, pgd, PAGE_SIZE);
+	cpu_replace_ttbr1(swapper_pg_dir);
 
-	/* Ensure the zero page is visible to the page table walker */
-	dsb(ishst);
+	pgd_clear_fixmap();
+	memblock_free(pgd_phys, PAGE_SIZE);
 
 	/*
-	 * TTBR0 is only used for the identity mapping at this stage. Make it
-	 * point to zero page to avoid speculatively fetching new entries.
+	 * We only reuse the PGD from the swapper_pg_dir, not the pud + pmd
+	 * allocated with it.
 	 */
-	cpu_set_reserved_ttbr0();
-	local_flush_tlb_all();
-	cpu_set_default_tcr_t0sz();
+	memblock_free(__pa(swapper_pg_dir) + PAGE_SIZE,
+		      SWAPPER_DIR_SIZE - PAGE_SIZE);
+
+	bootmem_init();
 }
 
 /*
@@ -562,21 +652,13 @@ void vmemmap_free(unsigned long start, unsigned long end)
 }
 #endif	/* CONFIG_SPARSEMEM_VMEMMAP */
 
-static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
-#if CONFIG_PGTABLE_LEVELS > 2
-static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss;
-#endif
-#if CONFIG_PGTABLE_LEVELS > 3
-static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss;
-#endif
-
 static inline pud_t * fixmap_pud(unsigned long addr)
 {
 	pgd_t *pgd = pgd_offset_k(addr);
 
 	BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd));
 
-	return pud_offset(pgd, addr);
+	return pud_offset_kimg(pgd, addr);
 }
 
 static inline pmd_t * fixmap_pmd(unsigned long addr)
@@ -585,16 +667,12 @@ static inline pmd_t * fixmap_pmd(unsigned long addr)
 
 	BUG_ON(pud_none(*pud) || pud_bad(*pud));
 
-	return pmd_offset(pud, addr);
+	return pmd_offset_kimg(pud, addr);
 }
 
 static inline pte_t * fixmap_pte(unsigned long addr)
 {
-	pmd_t *pmd = fixmap_pmd(addr);
-
-	BUG_ON(pmd_none(*pmd) || pmd_bad(*pmd));
-
-	return pte_offset_kernel(pmd, addr);
+	return &bm_pte[pte_index(addr)];
 }
 
 void __init early_fixmap_init(void)
@@ -605,15 +683,26 @@ void __init early_fixmap_init(void)
 	unsigned long addr = FIXADDR_START;
 
 	pgd = pgd_offset_k(addr);
-	pgd_populate(&init_mm, pgd, bm_pud);
-	pud = pud_offset(pgd, addr);
+	if (CONFIG_PGTABLE_LEVELS > 3 &&
+	    !(pgd_none(*pgd) || pgd_page_paddr(*pgd) == __pa(bm_pud))) {
+		/*
+		 * We only end up here if the kernel mapping and the fixmap
+		 * share the top level pgd entry, which should only happen on
+		 * 16k/4 levels configurations.
+		 */
+		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
+		pud = pud_offset_kimg(pgd, addr);
+	} else {
+		pgd_populate(&init_mm, pgd, bm_pud);
+		pud = fixmap_pud(addr);
+	}
 	pud_populate(&init_mm, pud, bm_pmd);
-	pmd = pmd_offset(pud, addr);
+	pmd = fixmap_pmd(addr);
 	pmd_populate_kernel(&init_mm, pmd, bm_pte);
 
 	/*
 	 * The boot-ioremap range spans multiple pmds, for which
-	 * we are not preparted:
+	 * we are not prepared:
 	 */
 	BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
 		     != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
@@ -652,11 +741,10 @@ void __set_fixmap(enum fixed_addresses idx,
 	}
 }
 
-void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
+void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
 {
 	const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
-	pgprot_t prot = PAGE_KERNEL_RO;
-	int size, offset;
+	int offset;
 	void *dt_virt;
 
 	/*
@@ -673,7 +761,7 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
 	/*
 	 * Make sure that the FDT region can be mapped without the need to
 	 * allocate additional translation table pages, so that it is safe
-	 * to call create_mapping() this early.
+	 * to call create_mapping_noalloc() this early.
 	 *
 	 * On 64k pages, the FDT will be mapped using PTEs, so we need to
 	 * be in the same PMD as the rest of the fixmap.
@@ -689,21 +777,73 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
 	dt_virt = (void *)dt_virt_base + offset;
 
 	/* map the first chunk so we can read the size from the header */
-	create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
-		       SWAPPER_BLOCK_SIZE, prot);
+	create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE),
+			dt_virt_base, SWAPPER_BLOCK_SIZE, prot);
 
 	if (fdt_check_header(dt_virt) != 0)
 		return NULL;
 
-	size = fdt_totalsize(dt_virt);
-	if (size > MAX_FDT_SIZE)
+	*size = fdt_totalsize(dt_virt);
+	if (*size > MAX_FDT_SIZE)
 		return NULL;
 
-	if (offset + size > SWAPPER_BLOCK_SIZE)
-		create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
-			       round_up(offset + size, SWAPPER_BLOCK_SIZE), prot);
+	if (offset + *size > SWAPPER_BLOCK_SIZE)
+		create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
+			       round_up(offset + *size, SWAPPER_BLOCK_SIZE), prot);
 
-	memblock_reserve(dt_phys, size);
+	return dt_virt;
+}
+
+void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
+{
+	void *dt_virt;
+	int size;
+
+	dt_virt = __fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL_RO);
+	if (!dt_virt)
+		return NULL;
 
+	memblock_reserve(dt_phys, size);
 	return dt_virt;
 }
+
+int __init arch_ioremap_pud_supported(void)
+{
+	/* only 4k granule supports level 1 block mappings */
+	return IS_ENABLED(CONFIG_ARM64_4K_PAGES);
+}
+
+int __init arch_ioremap_pmd_supported(void)
+{
+	return 1;
+}
+
+int pud_set_huge(pud_t *pud, phys_addr_t phys, pgprot_t prot)
+{
+	BUG_ON(phys & ~PUD_MASK);
+	set_pud(pud, __pud(phys | PUD_TYPE_SECT | pgprot_val(mk_sect_prot(prot))));
+	return 1;
+}
+
+int pmd_set_huge(pmd_t *pmd, phys_addr_t phys, pgprot_t prot)
+{
+	BUG_ON(phys & ~PMD_MASK);
+	set_pmd(pmd, __pmd(phys | PMD_TYPE_SECT | pgprot_val(mk_sect_prot(prot))));
+	return 1;
+}
+
+int pud_clear_huge(pud_t *pud)
+{
+	if (!pud_sect(*pud))
+		return 0;
+	pud_clear(pud);
+	return 1;
+}
+
+int pmd_clear_huge(pmd_t *pmd)
+{
+	if (!pmd_sect(*pmd))
+		return 0;
+	pmd_clear(pmd);
+	return 1;
+}