Merge nommu branch

1 files changed, 771 insertions, 0 deletions

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
new file mode 100644
index 000000000000..e566cbe4b222
--- /dev/null
+++ b/arch/arm/mm/mmu.c
@@ -0,0 +1,771 @@
+/*
+ *  linux/arch/arm/mm/mmu.c
+ *
+ *  Copyright (C) 1995-2005 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/mman.h>
+#include <linux/nodemask.h>
+
+#include <asm/mach-types.h>
+#include <asm/setup.h>
+#include <asm/sizes.h>
+#include <asm/tlb.h>
+
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+#include "mm.h"
+
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+
+extern void _stext, __data_start, _end;
+extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
+
+/*
+ * empty_zero_page is a special page that is used for
+ * zero-initialized data and COW.
+ */
+struct page *empty_zero_page;
+
+/*
+ * The pmd table for the upper-most set of pages.
+ */
+pmd_t *top_pmd;
+
+#define CPOLICY_UNCACHED	0
+#define CPOLICY_BUFFERED	1
+#define CPOLICY_WRITETHROUGH	2
+#define CPOLICY_WRITEBACK	3
+#define CPOLICY_WRITEALLOC	4
+
+static unsigned int cachepolicy __initdata = CPOLICY_WRITEBACK;
+static unsigned int ecc_mask __initdata = 0;
+pgprot_t pgprot_kernel;
+
+EXPORT_SYMBOL(pgprot_kernel);
+
+struct cachepolicy {
+	const char	policy[16];
+	unsigned int	cr_mask;
+	unsigned int	pmd;
+	unsigned int	pte;
+};
+
+static struct cachepolicy cache_policies[] __initdata = {
+	{
+		.policy		= "uncached",
+		.cr_mask	= CR_W|CR_C,
+		.pmd		= PMD_SECT_UNCACHED,
+		.pte		= 0,
+	}, {
+		.policy		= "buffered",
+		.cr_mask	= CR_C,
+		.pmd		= PMD_SECT_BUFFERED,
+		.pte		= PTE_BUFFERABLE,
+	}, {
+		.policy		= "writethrough",
+		.cr_mask	= 0,
+		.pmd		= PMD_SECT_WT,
+		.pte		= PTE_CACHEABLE,
+	}, {
+		.policy		= "writeback",
+		.cr_mask	= 0,
+		.pmd		= PMD_SECT_WB,
+		.pte		= PTE_BUFFERABLE|PTE_CACHEABLE,
+	}, {
+		.policy		= "writealloc",
+		.cr_mask	= 0,
+		.pmd		= PMD_SECT_WBWA,
+		.pte		= PTE_BUFFERABLE|PTE_CACHEABLE,
+	}
+};
+
+/*
+ * These are useful for identifing cache coherency
+ * problems by allowing the cache or the cache and
+ * writebuffer to be turned off.  (Note: the write
+ * buffer should not be on and the cache off).
+ */
+static void __init early_cachepolicy(char **p)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(cache_policies); i++) {
+		int len = strlen(cache_policies[i].policy);
+
+		if (memcmp(*p, cache_policies[i].policy, len) == 0) {
+			cachepolicy = i;
+			cr_alignment &= ~cache_policies[i].cr_mask;
+			cr_no_alignment &= ~cache_policies[i].cr_mask;
+			*p += len;
+			break;
+		}
+	}
+	if (i == ARRAY_SIZE(cache_policies))
+		printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n");
+	flush_cache_all();
+	set_cr(cr_alignment);
+}
+__early_param("cachepolicy=", early_cachepolicy);
+
+static void __init early_nocache(char **__unused)
+{
+	char *p = "buffered";
+	printk(KERN_WARNING "nocache is deprecated; use cachepolicy=%s\n", p);
+	early_cachepolicy(&p);
+}
+__early_param("nocache", early_nocache);
+
+static void __init early_nowrite(char **__unused)
+{
+	char *p = "uncached";
+	printk(KERN_WARNING "nowb is deprecated; use cachepolicy=%s\n", p);
+	early_cachepolicy(&p);
+}
+__early_param("nowb", early_nowrite);
+
+static void __init early_ecc(char **p)
+{
+	if (memcmp(*p, "on", 2) == 0) {
+		ecc_mask = PMD_PROTECTION;
+		*p += 2;
+	} else if (memcmp(*p, "off", 3) == 0) {
+		ecc_mask = 0;
+		*p += 3;
+	}
+}
+__early_param("ecc=", early_ecc);
+
+static int __init noalign_setup(char *__unused)
+{
+	cr_alignment &= ~CR_A;
+	cr_no_alignment &= ~CR_A;
+	set_cr(cr_alignment);
+	return 1;
+}
+__setup("noalign", noalign_setup);
+
+struct mem_types {
+	unsigned int	prot_pte;
+	unsigned int	prot_l1;
+	unsigned int	prot_sect;
+	unsigned int	domain;
+};
+
+static struct mem_types mem_types[] __initdata = {
+	[MT_DEVICE] = {
+		.prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
+				L_PTE_WRITE,
+		.prot_l1   = PMD_TYPE_TABLE,
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_UNCACHED |
+				PMD_SECT_AP_WRITE,
+		.domain    = DOMAIN_IO,
+	},
+	[MT_CACHECLEAN] = {
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4,
+		.domain    = DOMAIN_KERNEL,
+	},
+	[MT_MINICLEAN] = {
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_MINICACHE,
+		.domain    = DOMAIN_KERNEL,
+	},
+	[MT_LOW_VECTORS] = {
+		.prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
+				L_PTE_EXEC,
+		.prot_l1   = PMD_TYPE_TABLE,
+		.domain    = DOMAIN_USER,
+	},
+	[MT_HIGH_VECTORS] = {
+		.prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
+				L_PTE_USER | L_PTE_EXEC,
+		.prot_l1   = PMD_TYPE_TABLE,
+		.domain    = DOMAIN_USER,
+	},
+	[MT_MEMORY] = {
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_AP_WRITE,
+		.domain    = DOMAIN_KERNEL,
+	},
+	[MT_ROM] = {
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4,
+		.domain    = DOMAIN_KERNEL,
+	},
+	[MT_IXP2000_DEVICE] = { /* IXP2400 requires XCB=101 for on-chip I/O */
+		.prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
+				L_PTE_WRITE,
+		.prot_l1   = PMD_TYPE_TABLE,
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_UNCACHED |
+				PMD_SECT_AP_WRITE | PMD_SECT_BUFFERABLE |
+				PMD_SECT_TEX(1),
+		.domain    = DOMAIN_IO,
+	},
+	[MT_NONSHARED_DEVICE] = {
+		.prot_l1   = PMD_TYPE_TABLE,
+		.prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_NONSHARED_DEV |
+				PMD_SECT_AP_WRITE,
+		.domain    = DOMAIN_IO,
+	}
+};
+
+/*
+ * Adjust the PMD section entries according to the CPU in use.
+ */
+static void __init build_mem_type_table(void)
+{
+	struct cachepolicy *cp;
+	unsigned int cr = get_cr();
+	unsigned int user_pgprot, kern_pgprot;
+	int cpu_arch = cpu_architecture();
+	int i;
+
+#if defined(CONFIG_CPU_DCACHE_DISABLE)
+	if (cachepolicy > CPOLICY_BUFFERED)
+		cachepolicy = CPOLICY_BUFFERED;
+#elif defined(CONFIG_CPU_DCACHE_WRITETHROUGH)
+	if (cachepolicy > CPOLICY_WRITETHROUGH)
+		cachepolicy = CPOLICY_WRITETHROUGH;
+#endif
+	if (cpu_arch < CPU_ARCH_ARMv5) {
+		if (cachepolicy >= CPOLICY_WRITEALLOC)
+			cachepolicy = CPOLICY_WRITEBACK;
+		ecc_mask = 0;
+	}
+
+	/*
+	 * Xscale must not have PMD bit 4 set for section mappings.
+	 */
+	if (cpu_is_xscale())
+		for (i = 0; i < ARRAY_SIZE(mem_types); i++)
+			mem_types[i].prot_sect &= ~PMD_BIT4;
+
+	/*
+	 * ARMv5 and lower, excluding Xscale, bit 4 must be set for
+	 * page tables.
+	 */
+	if (cpu_arch < CPU_ARCH_ARMv6 && !cpu_is_xscale())
+		for (i = 0; i < ARRAY_SIZE(mem_types); i++)
+			if (mem_types[i].prot_l1)
+				mem_types[i].prot_l1 |= PMD_BIT4;
+
+	cp = &cache_policies[cachepolicy];
+	kern_pgprot = user_pgprot = cp->pte;
+
+	/*
+	 * Enable CPU-specific coherency if supported.
+	 * (Only available on XSC3 at the moment.)
+	 */
+	if (arch_is_coherent()) {
+		if (cpu_is_xsc3()) {
+			mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+			mem_types[MT_MEMORY].prot_pte |= L_PTE_COHERENT;
+		}
+	}
+
+	/*
+	 * ARMv6 and above have extended page tables.
+	 */
+	if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
+		/*
+		 * bit 4 becomes XN which we must clear for the
+		 * kernel memory mapping.
+		 */
+		mem_types[MT_MEMORY].prot_sect &= ~PMD_SECT_XN;
+		mem_types[MT_ROM].prot_sect &= ~PMD_SECT_XN;
+
+		/*
+		 * Mark cache clean areas and XIP ROM read only
+		 * from SVC mode and no access from userspace.
+		 */
+		mem_types[MT_ROM].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
+		mem_types[MT_MINICLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
+		mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
+
+		/*
+		 * Mark the device area as "shared device"
+		 */
+		mem_types[MT_DEVICE].prot_pte |= L_PTE_BUFFERABLE;
+		mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;
+
+		/*
+		 * User pages need to be mapped with the ASID
+		 * (iow, non-global)
+		 */
+		user_pgprot |= L_PTE_ASID;
+
+#ifdef CONFIG_SMP
+		/*
+		 * Mark memory with the "shared" attribute for SMP systems
+		 */
+		user_pgprot |= L_PTE_SHARED;
+		kern_pgprot |= L_PTE_SHARED;
+		mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+#endif
+	}
+
+	for (i = 0; i < 16; i++) {
+		unsigned long v = pgprot_val(protection_map[i]);
+		v = (v & ~(L_PTE_BUFFERABLE|L_PTE_CACHEABLE)) | user_pgprot;
+		protection_map[i] = __pgprot(v);
+	}
+
+	mem_types[MT_LOW_VECTORS].prot_pte |= kern_pgprot;
+	mem_types[MT_HIGH_VECTORS].prot_pte |= kern_pgprot;
+
+	if (cpu_arch >= CPU_ARCH_ARMv5) {
+#ifndef CONFIG_SMP
+		/*
+		 * Only use write-through for non-SMP systems
+		 */
+		mem_types[MT_LOW_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
+		mem_types[MT_HIGH_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
+#endif
+	} else {
+		mem_types[MT_MINICLEAN].prot_sect &= ~PMD_SECT_TEX(1);
+	}
+
+	pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
+				 L_PTE_DIRTY | L_PTE_WRITE |
+				 L_PTE_EXEC | kern_pgprot);
+
+	mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
+	mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;
+	mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd;
+	mem_types[MT_ROM].prot_sect |= cp->pmd;
+
+	switch (cp->pmd) {
+	case PMD_SECT_WT:
+		mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WT;
+		break;
+	case PMD_SECT_WB:
+	case PMD_SECT_WBWA:
+		mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WB;
+		break;
+	}
+	printk("Memory policy: ECC %sabled, Data cache %s\n",
+		ecc_mask ? "en" : "dis", cp->policy);
+}
+
+#define vectors_base()	(vectors_high() ? 0xffff0000 : 0)
+
+/*
+ * Create a SECTION PGD between VIRT and PHYS in domain
+ * DOMAIN with protection PROT.  This operates on half-
+ * pgdir entry increments.
+ */
+static inline void
+alloc_init_section(unsigned long virt, unsigned long phys, int prot)
+{
+	pmd_t *pmdp = pmd_off_k(virt);
+
+	if (virt & (1 << 20))
+		pmdp++;
+
+	*pmdp = __pmd(phys | prot);
+	flush_pmd_entry(pmdp);
+}
+
+/*
+ * Create a SUPER SECTION PGD between VIRT and PHYS with protection PROT
+ */
+static inline void
+alloc_init_supersection(unsigned long virt, unsigned long phys, int prot)
+{
+	int i;
+
+	for (i = 0; i < 16; i += 1) {
+		alloc_init_section(virt, phys, prot | PMD_SECT_SUPER);
+
+		virt += (PGDIR_SIZE / 2);
+	}
+}
+
+/*
+ * Add a PAGE mapping between VIRT and PHYS in domain
+ * DOMAIN with protection PROT.  Note that due to the
+ * way we map the PTEs, we must allocate two PTE_SIZE'd
+ * blocks - one for the Linux pte table, and one for
+ * the hardware pte table.
+ */
+static inline void
+alloc_init_page(unsigned long virt, unsigned long phys, unsigned int prot_l1, pgprot_t prot)
+{
+	pmd_t *pmdp = pmd_off_k(virt);
+	pte_t *ptep;
+
+	if (pmd_none(*pmdp)) {
+		ptep = alloc_bootmem_low_pages(2 * PTRS_PER_PTE *
+					       sizeof(pte_t));
+
+		__pmd_populate(pmdp, __pa(ptep) | prot_l1);
+	}
+	ptep = pte_offset_kernel(pmdp, virt);
+
+	set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot));
+}
+
+/*
+ * Create the page directory entries and any necessary
+ * page tables for the mapping specified by `md'.  We
+ * are able to cope here with varying sizes and address
+ * offsets, and we take full advantage of sections and
+ * supersections.
+ */
+void __init create_mapping(struct map_desc *md)
+{
+	unsigned long virt, length;
+	int prot_sect, prot_l1, domain;
+	pgprot_t prot_pte;
+	unsigned long off = (u32)__pfn_to_phys(md->pfn);
+
+	if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
+		printk(KERN_WARNING "BUG: not creating mapping for "
+		       "0x%08llx at 0x%08lx in user region\n",
+		       __pfn_to_phys((u64)md->pfn), md->virtual);
+		return;
+	}
+
+	if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
+	    md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
+		printk(KERN_WARNING "BUG: mapping for 0x%08llx at 0x%08lx "
+		       "overlaps vmalloc space\n",
+		       __pfn_to_phys((u64)md->pfn), md->virtual);
+	}
+
+	domain	  = mem_types[md->type].domain;
+	prot_pte  = __pgprot(mem_types[md->type].prot_pte);
+	prot_l1   = mem_types[md->type].prot_l1 | PMD_DOMAIN(domain);
+	prot_sect = mem_types[md->type].prot_sect | PMD_DOMAIN(domain);
+
+	/*
+	 * Catch 36-bit addresses
+	 */
+	if(md->pfn >= 0x100000) {
+		if(domain) {
+			printk(KERN_ERR "MM: invalid domain in supersection "
+				"mapping for 0x%08llx at 0x%08lx\n",
+				__pfn_to_phys((u64)md->pfn), md->virtual);
+			return;
+		}
+		if((md->virtual | md->length | __pfn_to_phys(md->pfn))
+			& ~SUPERSECTION_MASK) {
+			printk(KERN_ERR "MM: cannot create mapping for "
+				"0x%08llx at 0x%08lx invalid alignment\n",
+				__pfn_to_phys((u64)md->pfn), md->virtual);
+			return;
+		}
+
+		/*
+		 * Shift bits [35:32] of address into bits [23:20] of PMD
+		 * (See ARMv6 spec).
+		 */
+		off |= (((md->pfn >> (32 - PAGE_SHIFT)) & 0xF) << 20);
+	}
+
+	virt   = md->virtual;
+	off   -= virt;
+	length = md->length;
+
+	if (mem_types[md->type].prot_l1 == 0 &&
+	    (virt & 0xfffff || (virt + off) & 0xfffff || (virt + length) & 0xfffff)) {
+		printk(KERN_WARNING "BUG: map for 0x%08lx at 0x%08lx can not "
+		       "be mapped using pages, ignoring.\n",
+		       __pfn_to_phys(md->pfn), md->virtual);
+		return;
+	}
+
+	while ((virt & 0xfffff || (virt + off) & 0xfffff) && length >= PAGE_SIZE) {
+		alloc_init_page(virt, virt + off, prot_l1, prot_pte);
+
+		virt   += PAGE_SIZE;
+		length -= PAGE_SIZE;
+	}
+
+	/* N.B.	ARMv6 supersections are only defined to work with domain 0.
+	 *	Since domain assignments can in fact be arbitrary, the
+	 *	'domain == 0' check below is required to insure that ARMv6
+	 *	supersections are only allocated for domain 0 regardless
+	 *	of the actual domain assignments in use.
+	 */
+	if ((cpu_architecture() >= CPU_ARCH_ARMv6 || cpu_is_xsc3())
+		&& domain == 0) {
+		/*
+		 * Align to supersection boundary if !high pages.
+		 * High pages have already been checked for proper
+		 * alignment above and they will fail the SUPSERSECTION_MASK
+		 * check because of the way the address is encoded into
+		 * offset.
+		 */
+		if (md->pfn <= 0x100000) {
+			while ((virt & ~SUPERSECTION_MASK ||
+			        (virt + off) & ~SUPERSECTION_MASK) &&
+				length >= (PGDIR_SIZE / 2)) {
+				alloc_init_section(virt, virt + off, prot_sect);
+
+				virt   += (PGDIR_SIZE / 2);
+				length -= (PGDIR_SIZE / 2);
+			}
+		}
+
+		while (length >= SUPERSECTION_SIZE) {
+			alloc_init_supersection(virt, virt + off, prot_sect);
+
+			virt   += SUPERSECTION_SIZE;
+			length -= SUPERSECTION_SIZE;
+		}
+	}
+
+	/*
+	 * A section mapping covers half a "pgdir" entry.
+	 */
+	while (length >= (PGDIR_SIZE / 2)) {
+		alloc_init_section(virt, virt + off, prot_sect);
+
+		virt   += (PGDIR_SIZE / 2);
+		length -= (PGDIR_SIZE / 2);
+	}
+
+	while (length >= PAGE_SIZE) {
+		alloc_init_page(virt, virt + off, prot_l1, prot_pte);
+
+		virt   += PAGE_SIZE;
+		length -= PAGE_SIZE;
+	}
+}
+
+/*
+ * Create the architecture specific mappings
+ */
+void __init iotable_init(struct map_desc *io_desc, int nr)
+{
+	int i;
+
+	for (i = 0; i < nr; i++)
+		create_mapping(io_desc + i);
+}
+
+static inline void prepare_page_table(struct meminfo *mi)
+{
+	unsigned long addr;
+
+	/*
+	 * Clear out all the mappings below the kernel image.
+	 */
+	for (addr = 0; addr < MODULE_START; addr += PGDIR_SIZE)
+		pmd_clear(pmd_off_k(addr));
+
+#ifdef CONFIG_XIP_KERNEL
+	/* The XIP kernel is mapped in the module area -- skip over it */
+	addr = ((unsigned long)&_etext + PGDIR_SIZE - 1) & PGDIR_MASK;
+#endif
+	for ( ; addr < PAGE_OFFSET; addr += PGDIR_SIZE)
+		pmd_clear(pmd_off_k(addr));
+
+	/*
+	 * Clear out all the kernel space mappings, except for the first
+	 * memory bank, up to the end of the vmalloc region.
+	 */
+	for (addr = __phys_to_virt(mi->bank[0].start + mi->bank[0].size);
+	     addr < VMALLOC_END; addr += PGDIR_SIZE)
+		pmd_clear(pmd_off_k(addr));
+}
+
+/*
+ * Reserve the various regions of node 0
+ */
+void __init reserve_node_zero(pg_data_t *pgdat)
+{
+	unsigned long res_size = 0;
+
+	/*
+	 * Register the kernel text and data with bootmem.
+	 * Note that this can only be in node 0.
+	 */
+#ifdef CONFIG_XIP_KERNEL
+	reserve_bootmem_node(pgdat, __pa(&__data_start), &_end - &__data_start);
+#else
+	reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);
+#endif
+
+	/*
+	 * Reserve the page tables.  These are already in use,
+	 * and can only be in node 0.
+	 */
+	reserve_bootmem_node(pgdat, __pa(swapper_pg_dir),
+			     PTRS_PER_PGD * sizeof(pgd_t));
+
+	/*
+	 * Hmm... This should go elsewhere, but we really really need to
+	 * stop things allocating the low memory; ideally we need a better
+	 * implementation of GFP_DMA which does not assume that DMA-able
+	 * memory starts at zero.
+	 */
+	if (machine_is_integrator() || machine_is_cintegrator())
+		res_size = __pa(swapper_pg_dir) - PHYS_OFFSET;
+
+	/*
+	 * These should likewise go elsewhere.  They pre-reserve the
+	 * screen memory region at the start of main system memory.
+	 */
+	if (machine_is_edb7211())
+		res_size = 0x00020000;
+	if (machine_is_p720t())
+		res_size = 0x00014000;
+
+#ifdef CONFIG_SA1111
+	/*
+	 * Because of the SA1111 DMA bug, we want to preserve our
+	 * precious DMA-able memory...
+	 */
+	res_size = __pa(swapper_pg_dir) - PHYS_OFFSET;
+#endif
+	if (res_size)
+		reserve_bootmem_node(pgdat, PHYS_OFFSET, res_size);
+}
+
+/*
+ * Set up device the mappings.  Since we clear out the page tables for all
+ * mappings above VMALLOC_END, we will remove any debug device mappings.
+ * This means you have to be careful how you debug this function, or any
+ * called function.  This means you can't use any function or debugging
+ * method which may touch any device, otherwise the kernel _will_ crash.
+ */
+static void __init devicemaps_init(struct machine_desc *mdesc)
+{
+	struct map_desc map;
+	unsigned long addr;
+	void *vectors;
+
+	/*
+	 * Allocate the vector page early.
+	 */
+	vectors = alloc_bootmem_low_pages(PAGE_SIZE);
+	BUG_ON(!vectors);
+
+	for (addr = VMALLOC_END; addr; addr += PGDIR_SIZE)
+		pmd_clear(pmd_off_k(addr));
+
+	/*
+	 * Map the kernel if it is XIP.
+	 * It is always first in the modulearea.
+	 */
+#ifdef CONFIG_XIP_KERNEL
+	map.pfn = __phys_to_pfn(CONFIG_XIP_PHYS_ADDR & SECTION_MASK);
+	map.virtual = MODULE_START;
+	map.length = ((unsigned long)&_etext - map.virtual + ~SECTION_MASK) & SECTION_MASK;
+	map.type = MT_ROM;
+	create_mapping(&map);
+#endif
+
+	/*
+	 * Map the cache flushing regions.
+	 */
+#ifdef FLUSH_BASE
+	map.pfn = __phys_to_pfn(FLUSH_BASE_PHYS);
+	map.virtual = FLUSH_BASE;
+	map.length = SZ_1M;
+	map.type = MT_CACHECLEAN;
+	create_mapping(&map);
+#endif
+#ifdef FLUSH_BASE_MINICACHE
+	map.pfn = __phys_to_pfn(FLUSH_BASE_PHYS + SZ_1M);
+	map.virtual = FLUSH_BASE_MINICACHE;
+	map.length = SZ_1M;
+	map.type = MT_MINICLEAN;
+	create_mapping(&map);
+#endif
+
+	/*
+	 * Create a mapping for the machine vectors at the high-vectors
+	 * location (0xffff0000).  If we aren't using high-vectors, also
+	 * create a mapping at the low-vectors virtual address.
+	 */
+	map.pfn = __phys_to_pfn(virt_to_phys(vectors));
+	map.virtual = 0xffff0000;
+	map.length = PAGE_SIZE;
+	map.type = MT_HIGH_VECTORS;
+	create_mapping(&map);
+
+	if (!vectors_high()) {
+		map.virtual = 0;
+		map.type = MT_LOW_VECTORS;
+		create_mapping(&map);
+	}
+
+	/*
+	 * Ask the machine support to map in the statically mapped devices.
+	 */
+	if (mdesc->map_io)
+		mdesc->map_io();
+
+	/*
+	 * Finally flush the caches and tlb to ensure that we're in a
+	 * consistent state wrt the writebuffer.  This also ensures that
+	 * any write-allocated cache lines in the vector page are written
+	 * back.  After this point, we can start to touch devices again.
+	 */
+	local_flush_tlb_all();
+	flush_cache_all();
+}
+
+/*
+ * paging_init() sets up the page tables, initialises the zone memory
+ * maps, and sets up the zero page, bad page and bad page tables.
+ */
+void __init paging_init(struct meminfo *mi, struct machine_desc *mdesc)
+{
+	void *zero_page;
+
+	build_mem_type_table();
+	prepare_page_table(mi);
+	bootmem_init(mi);
+	devicemaps_init(mdesc);
+
+	top_pmd = pmd_off_k(0xffff0000);
+
+	/*
+	 * allocate the zero page.  Note that we count on this going ok.
+	 */
+	zero_page = alloc_bootmem_low_pages(PAGE_SIZE);
+	memzero(zero_page, PAGE_SIZE);
+	empty_zero_page = virt_to_page(zero_page);
+	flush_dcache_page(empty_zero_page);
+}
+
+/*
+ * In order to soft-boot, we need to insert a 1:1 mapping in place of
+ * the user-mode pages.  This will then ensure that we have predictable
+ * results when turning the mmu off
+ */
+void setup_mm_for_reboot(char mode)
+{
+	unsigned long base_pmdval;
+	pgd_t *pgd;
+	int i;
+
+	if (current->mm && current->mm->pgd)
+		pgd = current->mm->pgd;
+	else
+		pgd = init_mm.pgd;
+
+	base_pmdval = PMD_SECT_AP_WRITE | PMD_SECT_AP_READ | PMD_TYPE_SECT;
+	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
+		base_pmdval |= PMD_BIT4;
+
+	for (i = 0; i < FIRST_USER_PGD_NR + USER_PTRS_PER_PGD; i++, pgd++) {
+		unsigned long pmdval = (i << PGDIR_SHIFT) | base_pmdval;
+		pmd_t *pmd;
+
+		pmd = pmd_off(pgd, i << PGDIR_SHIFT);
+		pmd[0] = __pmd(pmdval);
+		pmd[1] = __pmd(pmdval + (1 << (PGDIR_SHIFT - 1)));
+		flush_pmd_entry(pmd);
+	}
+}