arch/tile: core support for Tilera 32-bit chips.

This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.

This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 1082 insertions, 0 deletions

diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
new file mode 100644
index 000000000000..125ac53b60fc
--- /dev/null
+++ b/arch/tile/mm/init.c
@@ -0,0 +1,1082 @@
+/*
+ * Copyright (C) 1995  Linus Torvalds
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/poison.h>
+#include <linux/bootmem.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/efi.h>
+#include <linux/memory_hotplug.h>
+#include <linux/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/dma.h>
+#include <asm/fixmap.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/homecache.h>
+#include <hv/hypervisor.h>
+#include <arch/chip.h>
+
+#include "migrate.h"
+
+/*
+ * We could set FORCE_MAX_ZONEORDER to "(HPAGE_SHIFT - PAGE_SHIFT + 1)"
+ * in the Tile Kconfig, but this generates configure warnings.
+ * Do it here and force people to get it right to compile this file.
+ * The problem is that with 4KB small pages and 16MB huge pages,
+ * the default value doesn't allow us to group enough small pages
+ * together to make up a huge page.
+ */
+#if CONFIG_FORCE_MAX_ZONEORDER < HPAGE_SHIFT - PAGE_SHIFT + 1
+# error "Change FORCE_MAX_ZONEORDER in arch/tile/Kconfig to match page size"
+#endif
+
+#define clear_pgd(pmdptr) (*(pmdptr) = hv_pte(0))
+
+unsigned long VMALLOC_RESERVE = CONFIG_VMALLOC_RESERVE;
+
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+
+/* Create an L2 page table */
+static pte_t * __init alloc_pte(void)
+{
+	return __alloc_bootmem(L2_KERNEL_PGTABLE_SIZE, HV_PAGE_TABLE_ALIGN, 0);
+}
+
+/*
+ * L2 page tables per controller.  We allocate these all at once from
+ * the bootmem allocator and store them here.  This saves on kernel L2
+ * page table memory, compared to allocating a full 64K page per L2
+ * page table, and also means that in cases where we use huge pages,
+ * we are guaranteed to later be able to shatter those huge pages and
+ * switch to using these page tables instead, without requiring
+ * further allocation.  Each l2_ptes[] entry points to the first page
+ * table for the first hugepage-size piece of memory on the
+ * controller; other page tables are just indexed directly, i.e. the
+ * L2 page tables are contiguous in memory for each controller.
+ */
+static pte_t *l2_ptes[MAX_NUMNODES];
+static int num_l2_ptes[MAX_NUMNODES];
+
+static void init_prealloc_ptes(int node, int pages)
+{
+	BUG_ON(pages & (HV_L2_ENTRIES-1));
+	if (pages) {
+		num_l2_ptes[node] = pages;
+		l2_ptes[node] = __alloc_bootmem(pages * sizeof(pte_t),
+						HV_PAGE_TABLE_ALIGN, 0);
+	}
+}
+
+pte_t *get_prealloc_pte(unsigned long pfn)
+{
+	int node = pfn_to_nid(pfn);
+	pfn &= ~(-1UL << (NR_PA_HIGHBIT_SHIFT - PAGE_SHIFT));
+	BUG_ON(node >= MAX_NUMNODES);
+	BUG_ON(pfn >= num_l2_ptes[node]);
+	return &l2_ptes[node][pfn];
+}
+
+/*
+ * What caching do we expect pages from the heap to have when
+ * they are allocated during bootup?  (Once we've installed the
+ * "real" swapper_pg_dir.)
+ */
+static int initial_heap_home(void)
+{
+#if CHIP_HAS_CBOX_HOME_MAP()
+	if (hash_default)
+		return PAGE_HOME_HASH;
+#endif
+	return smp_processor_id();
+}
+
+/*
+ * Place a pointer to an L2 page table in a middle page
+ * directory entry.
+ */
+static void __init assign_pte(pmd_t *pmd, pte_t *page_table)
+{
+	phys_addr_t pa = __pa(page_table);
+	unsigned long l2_ptfn = pa >> HV_LOG2_PAGE_TABLE_ALIGN;
+	pte_t pteval = hv_pte_set_ptfn(__pgprot(_PAGE_TABLE), l2_ptfn);
+	BUG_ON((pa & (HV_PAGE_TABLE_ALIGN-1)) != 0);
+	pteval = pte_set_home(pteval, initial_heap_home());
+	*(pte_t *)pmd = pteval;
+	if (page_table != (pte_t *)pmd_page_vaddr(*pmd))
+		BUG();
+}
+
+#ifdef __tilegx__
+
+#if HV_L1_SIZE != HV_L2_SIZE
+# error Rework assumption that L1 and L2 page tables are same size.
+#endif
+
+/* Since pmd_t arrays and pte_t arrays are the same size, just use casts. */
+static inline pmd_t *alloc_pmd(void)
+{
+	return (pmd_t *)alloc_pte();
+}
+
+static inline void assign_pmd(pud_t *pud, pmd_t *pmd)
+{
+	assign_pte((pmd_t *)pud, (pte_t *)pmd);
+}
+
+#endif /* __tilegx__ */
+
+/* Replace the given pmd with a full PTE table. */
+void __init shatter_pmd(pmd_t *pmd)
+{
+	pte_t *pte = get_prealloc_pte(pte_pfn(*(pte_t *)pmd));
+	assign_pte(pmd, pte);
+}
+
+#ifdef CONFIG_HIGHMEM
+/*
+ * This function initializes a certain range of kernel virtual memory
+ * with new bootmem page tables, everywhere page tables are missing in
+ * the given range.
+ */
+
+/*
+ * NOTE: The pagetables are allocated contiguous on the physical space
+ * so we can cache the place of the first one and move around without
+ * checking the pgd every time.
+ */
+static void __init page_table_range_init(unsigned long start,
+					 unsigned long end, pgd_t *pgd_base)
+{
+	pgd_t *pgd;
+	int pgd_idx;
+	unsigned long vaddr;
+
+	vaddr = start;
+	pgd_idx = pgd_index(vaddr);
+	pgd = pgd_base + pgd_idx;
+
+	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
+		pmd_t *pmd = pmd_offset(pud_offset(pgd, vaddr), vaddr);
+		if (pmd_none(*pmd))
+			assign_pte(pmd, alloc_pte());
+		vaddr += PMD_SIZE;
+	}
+}
+#endif /* CONFIG_HIGHMEM */
+
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+
+static int __initdata ktext_hash = 1;  /* .text pages */
+static int __initdata kdata_hash = 1;  /* .data and .bss pages */
+int __write_once hash_default = 1;     /* kernel allocator pages */
+EXPORT_SYMBOL(hash_default);
+int __write_once kstack_hash = 1;      /* if no homecaching, use h4h */
+#endif /* CHIP_HAS_CBOX_HOME_MAP */
+
+/*
+ * CPUs to use to for striping the pages of kernel data.  If hash-for-home
+ * is available, this is only relevant if kcache_hash sets up the
+ * .data and .bss to be page-homed, and we don't want the default mode
+ * of using the full set of kernel cpus for the striping.
+ */
+static __initdata struct cpumask kdata_mask;
+static __initdata int kdata_arg_seen;
+
+int __write_once kdata_huge;       /* if no homecaching, small pages */
+
+
+/* Combine a generic pgprot_t with cache home to get a cache-aware pgprot. */
+static pgprot_t __init construct_pgprot(pgprot_t prot, int home)
+{
+	prot = pte_set_home(prot, home);
+#if CHIP_HAS_CBOX_HOME_MAP()
+	if (home == PAGE_HOME_IMMUTABLE) {
+		if (ktext_hash)
+			prot = hv_pte_set_mode(prot, HV_PTE_MODE_CACHE_HASH_L3);
+		else
+			prot = hv_pte_set_mode(prot, HV_PTE_MODE_CACHE_NO_L3);
+	}
+#endif
+	return prot;
+}
+
+/*
+ * For a given kernel data VA, how should it be cached?
+ * We return the complete pgprot_t with caching bits set.
+ */
+static pgprot_t __init init_pgprot(ulong address)
+{
+	int cpu;
+	unsigned long page;
+	enum { CODE_DELTA = MEM_SV_INTRPT - PAGE_OFFSET };
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+	/* For kdata=huge, everything is just hash-for-home. */
+	if (kdata_huge)
+		return construct_pgprot(PAGE_KERNEL, PAGE_HOME_HASH);
+#endif
+
+	/* We map the aliased pages of permanent text inaccessible. */
+	if (address < (ulong) _sinittext - CODE_DELTA)
+		return PAGE_NONE;
+
+	/*
+	 * We map read-only data non-coherent for performance.  We could
+	 * use neighborhood caching on TILE64, but it's not clear it's a win.
+	 */
+	if ((address >= (ulong) __start_rodata &&
+	     address < (ulong) __end_rodata) ||
+	    address == (ulong) empty_zero_page) {
+		return construct_pgprot(PAGE_KERNEL_RO, PAGE_HOME_IMMUTABLE);
+	}
+
+	/* As a performance optimization, keep the boot init stack here. */
+	if (address >= (ulong)&init_thread_union &&
+	    address < (ulong)&init_thread_union + THREAD_SIZE)
+		return construct_pgprot(PAGE_KERNEL, smp_processor_id());
+
+#ifndef __tilegx__
+#if !ATOMIC_LOCKS_FOUND_VIA_TABLE()
+	/* Force the atomic_locks[] array page to be hash-for-home. */
+	if (address == (ulong) atomic_locks)
+		return construct_pgprot(PAGE_KERNEL, PAGE_HOME_HASH);
+#endif
+#endif
+
+	/*
+	 * Everything else that isn't data or bss is heap, so mark it
+	 * with the initial heap home (hash-for-home, or this cpu).  This
+	 * includes any addresses after the loaded image; any address before
+	 * _einittext (since we already captured the case of text before
+	 * _sinittext); and any init-data pages.
+	 *
+	 * All the LOWMEM pages that we mark this way will get their
+	 * struct page homecache properly marked later, in set_page_homes().
+	 * The HIGHMEM pages we leave with a default zero for their
+	 * homes, but with a zero free_time we don't have to actually
+	 * do a flush action the first time we use them, either.
+	 */
+	if (address >= (ulong) _end || address < (ulong) _sdata ||
+	    (address >= (ulong) _sinitdata &&
+	     address < (ulong) _einitdata))
+		return construct_pgprot(PAGE_KERNEL, initial_heap_home());
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+	/* Use hash-for-home if requested for data/bss. */
+	if (kdata_hash)
+		return construct_pgprot(PAGE_KERNEL, PAGE_HOME_HASH);
+#endif
+
+	/*
+	 * Otherwise we just hand out consecutive cpus.  To avoid
+	 * requiring this function to hold state, we just walk forward from
+	 * _sdata by PAGE_SIZE, skipping the readonly and init data, to reach
+	 * the requested address, while walking cpu home around kdata_mask.
+	 * This is typically no more than a dozen or so iterations.
+	 */
+	BUG_ON(_einitdata != __bss_start);
+	for (page = (ulong)_sdata, cpu = NR_CPUS; ; ) {
+		cpu = cpumask_next(cpu, &kdata_mask);
+		if (cpu == NR_CPUS)
+			cpu = cpumask_first(&kdata_mask);
+		if (page >= address)
+			break;
+		page += PAGE_SIZE;
+		if (page == (ulong)__start_rodata)
+			page = (ulong)__end_rodata;
+		if (page == (ulong)&init_thread_union)
+			page += THREAD_SIZE;
+		if (page == (ulong)_sinitdata)
+			page = (ulong)_einitdata;
+		if (page == (ulong)empty_zero_page)
+			page += PAGE_SIZE;
+#ifndef __tilegx__
+#if !ATOMIC_LOCKS_FOUND_VIA_TABLE()
+		if (page == (ulong)atomic_locks)
+			page += PAGE_SIZE;
+#endif
+#endif
+
+	}
+	return construct_pgprot(PAGE_KERNEL, cpu);
+}
+
+/*
+ * This function sets up how we cache the kernel text.  If we have
+ * hash-for-home support, normally that is used instead (see the
+ * kcache_hash boot flag for more information).  But if we end up
+ * using a page-based caching technique, this option sets up the
+ * details of that.  In addition, the "ktext=nocache" option may
+ * always be used to disable local caching of text pages, if desired.
+ */
+
+static int __initdata ktext_arg_seen;
+static int __initdata ktext_small;
+static int __initdata ktext_local;
+static int __initdata ktext_all;
+static int __initdata ktext_nondataplane;
+static int __initdata ktext_nocache;
+static struct cpumask __initdata ktext_mask;
+
+static int __init setup_ktext(char *str)
+{
+	if (str == NULL)
+		return -EINVAL;
+
+	/* If you have a leading "nocache", turn off ktext caching */
+	if (strncmp(str, "nocache", 7) == 0) {
+		ktext_nocache = 1;
+		printk("ktext: disabling local caching of kernel text\n");
+		str += 7;
+		if (*str == ',')
+			++str;
+		if (*str == '\0')
+			return 0;
+	}
+
+	ktext_arg_seen = 1;
+
+	/* Default setting on Tile64: use a huge page */
+	if (strcmp(str, "huge") == 0)
+		printk("ktext: using one huge locally cached page\n");
+
+	/* Pay TLB cost but get no cache benefit: cache small pages locally */
+	else if (strcmp(str, "local") == 0) {
+		ktext_small = 1;
+		ktext_local = 1;
+		printk("ktext: using small pages with local caching\n");
+	}
+
+	/* Neighborhood cache ktext pages on all cpus. */
+	else if (strcmp(str, "all") == 0) {
+		ktext_small = 1;
+		ktext_all = 1;
+		printk("ktext: using maximal caching neighborhood\n");
+	}
+
+
+	/* Neighborhood ktext pages on specified mask */
+	else if (cpulist_parse(str, &ktext_mask) == 0) {
+		char buf[NR_CPUS * 5];
+		cpulist_scnprintf(buf, sizeof(buf), &ktext_mask);
+		if (cpumask_weight(&ktext_mask) > 1) {
+			ktext_small = 1;
+			printk("ktext: using caching neighborhood %s "
+			       "with small pages\n", buf);
+		} else {
+			printk("ktext: caching on cpu %s with one huge page\n",
+			       buf);
+		}
+	}
+
+	else if (*str)
+		return -EINVAL;
+
+	return 0;
+}
+
+early_param("ktext", setup_ktext);
+
+
+static inline pgprot_t ktext_set_nocache(pgprot_t prot)
+{
+	if (!ktext_nocache)
+		prot = hv_pte_set_nc(prot);
+#if CHIP_HAS_NC_AND_NOALLOC_BITS()
+	else
+		prot = hv_pte_set_no_alloc_l2(prot);
+#endif
+	return prot;
+}
+
+#ifndef __tilegx__
+static pmd_t *__init get_pmd(pgd_t pgtables[], unsigned long va)
+{
+	return pmd_offset(pud_offset(&pgtables[pgd_index(va)], va), va);
+}
+#else
+static pmd_t *__init get_pmd(pgd_t pgtables[], unsigned long va)
+{
+	pud_t *pud = pud_offset(&pgtables[pgd_index(va)], va);
+	if (pud_none(*pud))
+		assign_pmd(pud, alloc_pmd());
+	return pmd_offset(pud, va);
+}
+#endif
+
+/* Temporary page table we use for staging. */
+static pgd_t pgtables[PTRS_PER_PGD]
+ __attribute__((section(".init.page")));
+
+/*
+ * This maps the physical memory to kernel virtual address space, a total
+ * of max_low_pfn pages, by creating page tables starting from address
+ * PAGE_OFFSET.
+ *
+ * This routine transitions us from using a set of compiled-in large
+ * pages to using some more precise caching, including removing access
+ * to code pages mapped at PAGE_OFFSET (executed only at MEM_SV_START)
+ * marking read-only data as locally cacheable, striping the remaining
+ * .data and .bss across all the available tiles, and removing access
+ * to pages above the top of RAM (thus ensuring a page fault from a bad
+ * virtual address rather than a hypervisor shoot down for accessing
+ * memory outside the assigned limits).
+ */
+static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
+{
+	unsigned long address, pfn;
+	pmd_t *pmd;
+	pte_t *pte;
+	int pte_ofs;
+	const struct cpumask *my_cpu_mask = cpumask_of(smp_processor_id());
+	struct cpumask kstripe_mask;
+	int rc, i;
+
+#if CHIP_HAS_CBOX_HOME_MAP()
+	if (ktext_arg_seen && ktext_hash) {
+		printk("warning: \"ktext\" boot argument ignored"
+		       " if \"kcache_hash\" sets up text hash-for-home\n");
+		ktext_small = 0;
+	}
+
+	if (kdata_arg_seen && kdata_hash) {
+		printk("warning: \"kdata\" boot argument ignored"
+		       " if \"kcache_hash\" sets up data hash-for-home\n");
+	}
+
+	if (kdata_huge && !hash_default) {
+		printk("warning: disabling \"kdata=huge\"; requires"
+		       " kcache_hash=all or =allbutstack\n");
+		kdata_huge = 0;
+	}
+#endif
+
+	/*
+	 * Set up a mask for cpus to use for kernel striping.
+	 * This is normally all cpus, but minus dataplane cpus if any.
+	 * If the dataplane covers the whole chip, we stripe over
+	 * the whole chip too.
+	 */
+	cpumask_copy(&kstripe_mask, cpu_possible_mask);
+	if (!kdata_arg_seen)
+		kdata_mask = kstripe_mask;
+
+	/* Allocate and fill in L2 page tables */
+	for (i = 0; i < MAX_NUMNODES; ++i) {
+#ifdef CONFIG_HIGHMEM
+		unsigned long end_pfn = node_lowmem_end_pfn[i];
+#else
+		unsigned long end_pfn = node_end_pfn[i];
+#endif
+		unsigned long end_huge_pfn = 0;
+
+		/* Pre-shatter the last huge page to allow per-cpu pages. */
+		if (kdata_huge)
+			end_huge_pfn = end_pfn - (HPAGE_SIZE >> PAGE_SHIFT);
+
+		pfn = node_start_pfn[i];
+
+		/* Allocate enough memory to hold L2 page tables for node. */
+		init_prealloc_ptes(i, end_pfn - pfn);
+
+		address = (unsigned long) pfn_to_kaddr(pfn);
+		while (pfn < end_pfn) {
+			BUG_ON(address & (HPAGE_SIZE-1));
+			pmd = get_pmd(pgtables, address);
+			pte = get_prealloc_pte(pfn);
+			if (pfn < end_huge_pfn) {
+				pgprot_t prot = init_pgprot(address);
+				*(pte_t *)pmd = pte_mkhuge(pfn_pte(pfn, prot));
+				for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE;
+				     pfn++, pte_ofs++, address += PAGE_SIZE)
+					pte[pte_ofs] = pfn_pte(pfn, prot);
+			} else {
+				if (kdata_huge)
+					printk(KERN_DEBUG "pre-shattered huge"
+					       " page at %#lx\n", address);
+				for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE;
+				     pfn++, pte_ofs++, address += PAGE_SIZE) {
+					pgprot_t prot = init_pgprot(address);
+					pte[pte_ofs] = pfn_pte(pfn, prot);
+				}
+				assign_pte(pmd, pte);
+			}
+		}
+	}
+
+	/*
+	 * Set or check ktext_map now that we have cpu_possible_mask
+	 * and kstripe_mask to work with.
+	 */
+	if (ktext_all)
+		cpumask_copy(&ktext_mask, cpu_possible_mask);
+	else if (ktext_nondataplane)
+		ktext_mask = kstripe_mask;
+	else if (!cpumask_empty(&ktext_mask)) {
+		/* Sanity-check any mask that was requested */
+		struct cpumask bad;
+		cpumask_andnot(&bad, &ktext_mask, cpu_possible_mask);
+		cpumask_and(&ktext_mask, &ktext_mask, cpu_possible_mask);
+		if (!cpumask_empty(&bad)) {
+			char buf[NR_CPUS * 5];
+			cpulist_scnprintf(buf, sizeof(buf), &bad);
+			printk("ktext: not using unavailable cpus %s\n", buf);
+		}
+		if (cpumask_empty(&ktext_mask)) {
+			printk("ktext: no valid cpus; caching on %d.\n",
+			       smp_processor_id());
+			cpumask_copy(&ktext_mask,
+				     cpumask_of(smp_processor_id()));
+		}
+	}
+
+	address = MEM_SV_INTRPT;
+	pmd = get_pmd(pgtables, address);
+	if (ktext_small) {
+		/* Allocate an L2 PTE for the kernel text */
+		int cpu = 0;
+		pgprot_t prot = construct_pgprot(PAGE_KERNEL_EXEC,
+						 PAGE_HOME_IMMUTABLE);
+
+		if (ktext_local) {
+			if (ktext_nocache)
+				prot = hv_pte_set_mode(prot,
+						       HV_PTE_MODE_UNCACHED);
+			else
+				prot = hv_pte_set_mode(prot,
+						       HV_PTE_MODE_CACHE_NO_L3);
+		} else {
+			prot = hv_pte_set_mode(prot,
+					       HV_PTE_MODE_CACHE_TILE_L3);
+			cpu = cpumask_first(&ktext_mask);
+
+			prot = ktext_set_nocache(prot);
+		}
+
+		BUG_ON(address != (unsigned long)_stext);
+		pfn = 0;  /* code starts at PA 0 */
+		pte = alloc_pte();
+		for (pte_ofs = 0; address < (unsigned long)_einittext;
+		     pfn++, pte_ofs++, address += PAGE_SIZE) {
+			if (!ktext_local) {
+				prot = set_remote_cache_cpu(prot, cpu);
+				cpu = cpumask_next(cpu, &ktext_mask);
+				if (cpu == NR_CPUS)
+					cpu = cpumask_first(&ktext_mask);
+			}
+			pte[pte_ofs] = pfn_pte(pfn, prot);
+		}
+		assign_pte(pmd, pte);
+	} else {
+		pte_t pteval = pfn_pte(0, PAGE_KERNEL_EXEC);
+		pteval = pte_mkhuge(pteval);
+#if CHIP_HAS_CBOX_HOME_MAP()
+		if (ktext_hash) {
+			pteval = hv_pte_set_mode(pteval,
+						 HV_PTE_MODE_CACHE_HASH_L3);
+			pteval = ktext_set_nocache(pteval);
+		} else
+#endif /* CHIP_HAS_CBOX_HOME_MAP() */
+		if (cpumask_weight(&ktext_mask) == 1) {
+			pteval = set_remote_cache_cpu(pteval,
+					      cpumask_first(&ktext_mask));
+			pteval = hv_pte_set_mode(pteval,
+						 HV_PTE_MODE_CACHE_TILE_L3);
+			pteval = ktext_set_nocache(pteval);
+		} else if (ktext_nocache)
+			pteval = hv_pte_set_mode(pteval,
+						 HV_PTE_MODE_UNCACHED);
+		else
+			pteval = hv_pte_set_mode(pteval,
+						 HV_PTE_MODE_CACHE_NO_L3);
+		*(pte_t *)pmd = pteval;
+	}
+
+	/* Set swapper_pgprot here so it is flushed to memory right away. */
+	swapper_pgprot = init_pgprot((unsigned long)swapper_pg_dir);
+
+	/*
+	 * Since we may be changing the caching of the stack and page
+	 * table itself, we invoke an assembly helper to do the
+	 * following steps:
+	 *
+	 *  - flush the cache so we start with an empty slate
+	 *  - install pgtables[] as the real page table
+	 *  - flush the TLB so the new page table takes effect
+	 */
+	rc = flush_and_install_context(__pa(pgtables),
+				       init_pgprot((unsigned long)pgtables),
+				       __get_cpu_var(current_asid),
+				       cpumask_bits(my_cpu_mask));
+	BUG_ON(rc != 0);
+
+	/* Copy the page table back to the normal swapper_pg_dir. */
+	memcpy(pgd_base, pgtables, sizeof(pgtables));
+	__install_page_table(pgd_base, __get_cpu_var(current_asid),
+			     swapper_pgprot);
+}
+
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address
+ * is valid. The argument is a physical page number.
+ *
+ * On Tile, the only valid things for which we can just hand out unchecked
+ * PTEs are the kernel code and data.  Anything else might change its
+ * homing with time, and we wouldn't know to adjust the /dev/mem PTEs.
+ * Note that init_thread_union is released to heap soon after boot,
+ * so we include it in the init data.
+ *
+ * For TILE-Gx, we might want to consider allowing access to PA
+ * regions corresponding to PCI space, etc.
+ */
+int devmem_is_allowed(unsigned long pagenr)
+{
+	return pagenr < kaddr_to_pfn(_end) &&
+		!(pagenr >= kaddr_to_pfn(&init_thread_union) ||
+		  pagenr < kaddr_to_pfn(_einitdata)) &&
+		!(pagenr >= kaddr_to_pfn(_sinittext) ||
+		  pagenr <= kaddr_to_pfn(_einittext-1));
+}
+
+#ifdef CONFIG_HIGHMEM
+static void __init permanent_kmaps_init(pgd_t *pgd_base)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	unsigned long vaddr;
+
+	vaddr = PKMAP_BASE;
+	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
+
+	pgd = swapper_pg_dir + pgd_index(vaddr);
+	pud = pud_offset(pgd, vaddr);
+	pmd = pmd_offset(pud, vaddr);
+	pte = pte_offset_kernel(pmd, vaddr);
+	pkmap_page_table = pte;
+}
+#endif /* CONFIG_HIGHMEM */
+
+
+static void __init init_free_pfn_range(unsigned long start, unsigned long end)
+{
+	unsigned long pfn;
+	struct page *page = pfn_to_page(start);
+
+	for (pfn = start; pfn < end; ) {
+		/* Optimize by freeing pages in large batches */
+		int order = __ffs(pfn);
+		int count, i;
+		struct page *p;
+
+		if (order >= MAX_ORDER)
+			order = MAX_ORDER-1;
+		count = 1 << order;
+		while (pfn + count > end) {
+			count >>= 1;
+			--order;
+		}
+		for (p = page, i = 0; i < count; ++i, ++p) {
+			__ClearPageReserved(p);
+			/*
+			 * Hacky direct set to avoid unnecessary
+			 * lock take/release for EVERY page here.
+			 */
+			p->_count.counter = 0;
+			p->_mapcount.counter = -1;
+		}
+		init_page_count(page);
+		__free_pages(page, order);
+		totalram_pages += count;
+
+		page += count;
+		pfn += count;
+	}
+}
+
+static void __init set_non_bootmem_pages_init(void)
+{
+	struct zone *z;
+	for_each_zone(z) {
+		unsigned long start, end;
+		int nid = z->zone_pgdat->node_id;
+
+		start = z->zone_start_pfn;
+		if (start == 0)
+			continue;  /* bootmem */
+		end = start + z->spanned_pages;
+		if (zone_idx(z) == ZONE_NORMAL) {
+			BUG_ON(start != node_start_pfn[nid]);
+			start = node_free_pfn[nid];
+		}
+#ifdef CONFIG_HIGHMEM
+		if (zone_idx(z) == ZONE_HIGHMEM)
+			totalhigh_pages += z->spanned_pages;
+#endif
+		if (kdata_huge) {
+			unsigned long percpu_pfn = node_percpu_pfn[nid];
+			if (start < percpu_pfn && end > percpu_pfn)
+				end = percpu_pfn;
+		}
+#ifdef CONFIG_PCI
+		if (start <= pci_reserve_start_pfn &&
+		    end > pci_reserve_start_pfn) {
+			if (end > pci_reserve_end_pfn)
+				init_free_pfn_range(pci_reserve_end_pfn, end);
+			end = pci_reserve_start_pfn;
+		}
+#endif
+		init_free_pfn_range(start, end);
+	}
+}
+
+/*
+ * paging_init() sets up the page tables - note that all of lowmem is
+ * already mapped by head.S.
+ */
+void __init paging_init(void)
+{
+#ifdef CONFIG_HIGHMEM
+	unsigned long vaddr, end;
+#endif
+#ifdef __tilegx__
+	pud_t *pud;
+#endif
+	pgd_t *pgd_base = swapper_pg_dir;
+
+	kernel_physical_mapping_init(pgd_base);
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * Fixed mappings, only the page table structure has to be
+	 * created - mappings will be set by set_fixmap():
+	 */
+	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
+	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
+	page_table_range_init(vaddr, end, pgd_base);
+	permanent_kmaps_init(pgd_base);
+#endif
+
+#ifdef __tilegx__
+	/*
+	 * Since GX allocates just one pmd_t array worth of vmalloc space,
+	 * we go ahead and allocate it statically here, then share it
+	 * globally.  As a result we don't have to worry about any task
+	 * changing init_mm once we get up and running, and there's no
+	 * need for e.g. vmalloc_sync_all().
+	 */
+	BUILD_BUG_ON(pgd_index(VMALLOC_START) != pgd_index(VMALLOC_END));
+	pud = pud_offset(pgd_base + pgd_index(VMALLOC_START), VMALLOC_START);
+	assign_pmd(pud, alloc_pmd());
+#endif
+}
+
+
+/*
+ * Walk the kernel page tables and derive the page_home() from
+ * the PTEs, so that set_pte() can properly validate the caching
+ * of all PTEs it sees.
+ */
+void __init set_page_homes(void)
+{
+}
+
+static void __init set_max_mapnr_init(void)
+{
+#ifdef CONFIG_FLATMEM
+	max_mapnr = max_low_pfn;
+#endif
+}
+
+void __init mem_init(void)
+{
+	int codesize, datasize, initsize;
+	int i;
+#ifndef __tilegx__
+	void *last;
+#endif
+
+#ifdef CONFIG_FLATMEM
+	if (!mem_map)
+		BUG();
+#endif
+
+#ifdef CONFIG_HIGHMEM
+	/* check that fixmap and pkmap do not overlap */
+	if (PKMAP_ADDR(LAST_PKMAP-1) >= FIXADDR_START) {
+		printk(KERN_ERR "fixmap and kmap areas overlap"
+		       " - this will crash\n");
+		printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
+		       PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP-1),
+		       FIXADDR_START);
+		BUG();
+	}
+#endif
+
+	set_max_mapnr_init();
+
+	/* this will put all bootmem onto the freelists */
+	totalram_pages += free_all_bootmem();
+
+	/* count all remaining LOWMEM and give all HIGHMEM to page allocator */
+	set_non_bootmem_pages_init();
+
+	codesize =  (unsigned long)&_etext - (unsigned long)&_text;
+	datasize =  (unsigned long)&_end - (unsigned long)&_sdata;
+	initsize =  (unsigned long)&_einittext - (unsigned long)&_sinittext;
+	initsize += (unsigned long)&_einitdata - (unsigned long)&_sinitdata;
+
+	printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk data, %dk init, %ldk highmem)\n",
+		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
+		num_physpages << (PAGE_SHIFT-10),
+		codesize >> 10,
+		datasize >> 10,
+		initsize >> 10,
+		(unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
+	       );
+
+	/*
+	 * In debug mode, dump some interesting memory mappings.
+	 */
+#ifdef CONFIG_HIGHMEM
+	printk(KERN_DEBUG "  KMAP    %#lx - %#lx\n",
+	       FIXADDR_START, FIXADDR_TOP + PAGE_SIZE - 1);
+	printk(KERN_DEBUG "  PKMAP   %#lx - %#lx\n",
+	       PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP) - 1);
+#endif
+#ifdef CONFIG_HUGEVMAP
+	printk(KERN_DEBUG "  HUGEMAP %#lx - %#lx\n",
+	       HUGE_VMAP_BASE, HUGE_VMAP_END - 1);
+#endif
+	printk(KERN_DEBUG "  VMALLOC %#lx - %#lx\n",
+	       _VMALLOC_START, _VMALLOC_END - 1);
+#ifdef __tilegx__
+	for (i = MAX_NUMNODES-1; i >= 0; --i) {
+		struct pglist_data *node = &node_data[i];
+		if (node->node_present_pages) {
+			unsigned long start = (unsigned long)
+				pfn_to_kaddr(node->node_start_pfn);
+			unsigned long end = start +
+				(node->node_present_pages << PAGE_SHIFT);
+			printk(KERN_DEBUG "  MEM%d    %#lx - %#lx\n",
+			       i, start, end - 1);
+		}
+	}
+#else
+	last = high_memory;
+	for (i = MAX_NUMNODES-1; i >= 0; --i) {
+		if ((unsigned long)vbase_map[i] != -1UL) {
+			printk(KERN_DEBUG "  LOWMEM%d %#lx - %#lx\n",
+			       i, (unsigned long) (vbase_map[i]),
+			       (unsigned long) (last-1));
+			last = vbase_map[i];
+		}
+	}
+#endif
+
+#ifndef __tilegx__
+	/*
+	 * Convert from using one lock for all atomic operations to
+	 * one per cpu.
+	 */
+	__init_atomic_per_cpu();
+#endif
+}
+
+/*
+ * this is for the non-NUMA, single node SMP system case.
+ * Specifically, in the case of x86, we will always add
+ * memory to the highmem for now.
+ */
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+int arch_add_memory(u64 start, u64 size)
+{
+	struct pglist_data *pgdata = &contig_page_data;
+	struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1;
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+
+	return __add_pages(zone, start_pfn, nr_pages);
+}
+
+int remove_memory(u64 start, u64 size)
+{
+	return -EINVAL;
+}
+#endif
+
+struct kmem_cache *pgd_cache;
+
+void __init pgtable_cache_init(void)
+{
+	pgd_cache = kmem_cache_create("pgd",
+				PTRS_PER_PGD*sizeof(pgd_t),
+				PTRS_PER_PGD*sizeof(pgd_t),
+				0,
+				NULL);
+	if (!pgd_cache)
+		panic("pgtable_cache_init(): Cannot create pgd cache");
+}
+
+#if !CHIP_HAS_COHERENT_LOCAL_CACHE()
+/*
+ * The __w1data area holds data that is only written during initialization,
+ * and is read-only and thus freely cacheable thereafter.  Fix the page
+ * table entries that cover that region accordingly.
+ */
+static void mark_w1data_ro(void)
+{
+	/* Loop over page table entries */
+	unsigned long addr = (unsigned long)__w1data_begin;
+	BUG_ON((addr & (PAGE_SIZE-1)) != 0);
+	for (; addr <= (unsigned long)__w1data_end - 1; addr += PAGE_SIZE) {
+		unsigned long pfn = kaddr_to_pfn((void *)addr);
+		struct page *page = pfn_to_page(pfn);
+		pte_t *ptep = virt_to_pte(NULL, addr);
+		BUG_ON(pte_huge(*ptep));   /* not relevant for kdata_huge */
+		set_pte_at(&init_mm, addr, ptep, pfn_pte(pfn, PAGE_KERNEL_RO));
+	}
+}
+#endif
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+static long __write_once initfree;
+#else
+static long __write_once initfree = 1;
+#endif
+
+/* Select whether to free (1) or mark unusable (0) the __init pages. */
+static int __init set_initfree(char *str)
+{
+	strict_strtol(str, 0, &initfree);
+	printk("initfree: %s free init pages\n", initfree ? "will" : "won't");
+	return 1;
+}
+__setup("initfree=", set_initfree);
+
+static void free_init_pages(char *what, unsigned long begin, unsigned long end)
+{
+	unsigned long addr = (unsigned long) begin;
+
+	if (kdata_huge && !initfree) {
+		printk("Warning: ignoring initfree=0:"
+		       " incompatible with kdata=huge\n");
+		initfree = 1;
+	}
+	end = (end + PAGE_SIZE - 1) & PAGE_MASK;
+	local_flush_tlb_pages(NULL, begin, PAGE_SIZE, end - begin);
+	for (addr = begin; addr < end; addr += PAGE_SIZE) {
+		/*
+		 * Note we just reset the home here directly in the
+		 * page table.  We know this is safe because our caller
+		 * just flushed the caches on all the other cpus,
+		 * and they won't be touching any of these pages.
+		 */
+		int pfn = kaddr_to_pfn((void *)addr);
+		struct page *page = pfn_to_page(pfn);
+		pte_t *ptep = virt_to_pte(NULL, addr);
+		if (!initfree) {
+			/*
+			 * If debugging page accesses then do not free
+			 * this memory but mark them not present - any
+			 * buggy init-section access will create a
+			 * kernel page fault:
+			 */
+			pte_clear(&init_mm, addr, ptep);
+			continue;
+		}
+		__ClearPageReserved(page);
+		init_page_count(page);
+		if (pte_huge(*ptep))
+			BUG_ON(!kdata_huge);
+		else
+			set_pte_at(&init_mm, addr, ptep,
+				   pfn_pte(pfn, PAGE_KERNEL));
+		memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
+		free_page(addr);
+		totalram_pages++;
+	}
+	printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
+}
+
+void free_initmem(void)
+{
+	const unsigned long text_delta = MEM_SV_INTRPT - PAGE_OFFSET;
+
+	/*
+	 * Evict the dirty initdata on the boot cpu, evict the w1data
+	 * wherever it's homed, and evict all the init code everywhere.
+	 * We are guaranteed that no one will touch the init pages any
+	 * more, and although other cpus may be touching the w1data,
+	 * we only actually change the caching on tile64, which won't
+	 * be keeping local copies in the other tiles' caches anyway.
+	 */
+	homecache_evict(&cpu_cacheable_map);
+
+	/* Free the data pages that we won't use again after init. */
+	free_init_pages("unused kernel data",
+			(unsigned long)_sinitdata,
+			(unsigned long)_einitdata);
+
+	/*
+	 * Free the pages mapped from 0xc0000000 that correspond to code
+	 * pages from 0xfd000000 that we won't use again after init.
+	 */
+	free_init_pages("unused kernel text",
+			(unsigned long)_sinittext - text_delta,
+			(unsigned long)_einittext - text_delta);
+
+#if !CHIP_HAS_COHERENT_LOCAL_CACHE()
+	/*
+	 * Upgrade the .w1data section to globally cached.
+	 * We don't do this on tilepro, since the cache architecture
+	 * pretty much makes it irrelevant, and in any case we end
+	 * up having racing issues with other tiles that may touch
+	 * the data after we flush the cache but before we update
+	 * the PTEs and flush the TLBs, causing sharer shootdowns
+	 * later.  Even though this is to clean data, it seems like
+	 * an unnecessary complication.
+	 */
+	mark_w1data_ro();
+#endif
+
+	/* Do a global TLB flush so everyone sees the changes. */
+	flush_tlb_all();
+}