arch/powerpc/mm/mem.c - kernel/msm-4.19 - Gitiles

 /*
  *  PowerPC version
  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  *
  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  *    Copyright (C) 1996 Paul Mackerras
  *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
  *
  *  Derived from "arch/i386/mm/init.c"
  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  *
  *  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; either version
  *  2 of the License, or (at your option) any later version.
  *
  */

 #include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/gfp.h>
 #include <linux/types.h>
 #include <linux/mm.h>
 #include <linux/stddef.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/highmem.h>
 #include <linux/initrd.h>
 #include <linux/pagemap.h>
 #include <linux/suspend.h>
 #include <linux/memblock.h>
 #include <linux/hugetlb.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>

 #include <asm/pgalloc.h>
 #include <asm/prom.h>
 #include <asm/io.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>
 #include <asm/smp.h>
 #include <asm/machdep.h>
 #include <asm/btext.h>
 #include <asm/tlb.h>
 #include <asm/sections.h>
 #include <asm/sparsemem.h>
 #include <asm/vdso.h>
 #include <asm/fixmap.h>
 #include <asm/swiotlb.h>
 #include <asm/rtas.h>

 #include "mmu_decl.h"

 #ifndef CPU_FTR_COHERENT_ICACHE
 #define CPU_FTR_COHERENT_ICACHE	0	/* XXX for now */
 #define CPU_FTR_NOEXECUTE	0
 #endif

 unsigned long long memory_limit;

 #ifdef CONFIG_HIGHMEM
 pte_t *kmap_pte;
 EXPORT_SYMBOL(kmap_pte);
 pgprot_t kmap_prot;
 EXPORT_SYMBOL(kmap_prot);

 static inline pte_t *virt_to_kpte(unsigned long vaddr)
 {
 	return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
 			vaddr), vaddr), vaddr);
 }
 #endif

 int page_is_ram(unsigned long pfn)
 {
 #ifndef CONFIG_PPC64	/* XXX for now */
 	return pfn < max_pfn;
 #else
 	unsigned long paddr = (pfn << PAGE_SHIFT);
 	struct memblock_region *reg;

 	for_each_memblock(memory, reg)
 		if (paddr >= reg->base && paddr < (reg->base + reg->size))
 			return 1;
 	return 0;
 #endif
 }

 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 			      unsigned long size, pgprot_t vma_prot)
 {
 	if (ppc_md.phys_mem_access_prot)
 		return ppc_md.phys_mem_access_prot(file, pfn, size, vma_prot);

 	if (!page_is_ram(pfn))
 		vma_prot = pgprot_noncached(vma_prot);

 	return vma_prot;
 }
 EXPORT_SYMBOL(phys_mem_access_prot);

 #ifdef CONFIG_MEMORY_HOTPLUG

 #ifdef CONFIG_NUMA
 int memory_add_physaddr_to_nid(u64 start)
 {
 	return hot_add_scn_to_nid(start);
 }
 #endif

 int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 {
 	struct pglist_data *pgdata;
 	struct zone *zone;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

 	pgdata = NODE_DATA(nid);

 	start = (unsigned long)__va(start);
 	if (create_section_mapping(start, start + size))
 		return -EINVAL;

 	/* this should work for most non-highmem platforms */
 	zone = pgdata->node_zones +
 		zone_for_memory(nid, start, size, 0, for_device);

 	return __add_pages(nid, zone, start_pfn, nr_pages);
 }

 #ifdef CONFIG_MEMORY_HOTREMOVE
 int arch_remove_memory(u64 start, u64 size)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 	int ret;

 	zone = page_zone(pfn_to_page(start_pfn));
 	ret = __remove_pages(zone, start_pfn, nr_pages);
 	if (ret)
 		return ret;

 	/* Remove htab bolted mappings for this section of memory */
 	start = (unsigned long)__va(start);
 	ret = remove_section_mapping(start, start + size);

 	/* Ensure all vmalloc mappings are flushed in case they also
 	 * hit that section of memory
 	 */
 	vm_unmap_aliases();

 	return ret;
 }
 #endif
 #endif /* CONFIG_MEMORY_HOTPLUG */

 /*
  * walk_memory_resource() needs to make sure there is no holes in a given
  * memory range.  PPC64 does not maintain the memory layout in /proc/iomem.
  * Instead it maintains it in memblock.memory structures.  Walk through the
  * memory regions, find holes and callback for contiguous regions.
  */
 int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *))
 {
 	struct memblock_region *reg;
 	unsigned long end_pfn = start_pfn + nr_pages;
 	unsigned long tstart, tend;
 	int ret = -1;

 	for_each_memblock(memory, reg) {
 		tstart = max(start_pfn, memblock_region_memory_base_pfn(reg));
 		tend = min(end_pfn, memblock_region_memory_end_pfn(reg));
 		if (tstart >= tend)
 			continue;
 		ret = (*func)(tstart, tend - tstart, arg);
 		if (ret)
 			break;
 	}
 	return ret;
 }
 EXPORT_SYMBOL_GPL(walk_system_ram_range);

 #ifndef CONFIG_NEED_MULTIPLE_NODES
 void __init initmem_init(void)
 {
 	max_low_pfn = max_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
 	min_low_pfn = MEMORY_START >> PAGE_SHIFT;
 #ifdef CONFIG_HIGHMEM
 	max_low_pfn = lowmem_end_addr >> PAGE_SHIFT;
 #endif

 	/* Place all memblock_regions in the same node and merge contiguous
 	 * memblock_regions
 	 */
 	memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0);

 	/* XXX need to clip this if using highmem? */
 	sparse_memory_present_with_active_regions(0);
 	sparse_init();
 }

 /* mark pages that don't exist as nosave */
 static int __init mark_nonram_nosave(void)
 {
 	struct memblock_region *reg, *prev = NULL;

 	for_each_memblock(memory, reg) {
 		if (prev &&
 		    memblock_region_memory_end_pfn(prev) < memblock_region_memory_base_pfn(reg))
 			register_nosave_region(memblock_region_memory_end_pfn(prev),
 					       memblock_region_memory_base_pfn(reg));
 		prev = reg;
 	}
 	return 0;
 }
 #else /* CONFIG_NEED_MULTIPLE_NODES */
 static int __init mark_nonram_nosave(void)
 {
 	return 0;
 }
 #endif

 static bool zone_limits_final;

 static unsigned long max_zone_pfns[MAX_NR_ZONES] = {
 	[0 ... MAX_NR_ZONES - 1] = ~0UL
 };

 /*
  * Restrict the specified zone and all more restrictive zones
  * to be below the specified pfn.  May not be called after
  * paging_init().
  */
 void __init limit_zone_pfn(enum zone_type zone, unsigned long pfn_limit)
 {
 	int i;

 	if (WARN_ON(zone_limits_final))
 		return;

 	for (i = zone; i >= 0; i--) {
 		if (max_zone_pfns[i] > pfn_limit)
 			max_zone_pfns[i] = pfn_limit;
 	}
 }

 /*
  * Find the least restrictive zone that is entirely below the
  * specified pfn limit.  Returns < 0 if no suitable zone is found.
  *
  * pfn_limit must be u64 because it can exceed 32 bits even on 32-bit
  * systems -- the DMA limit can be higher than any possible real pfn.
  */
 int dma_pfn_limit_to_zone(u64 pfn_limit)
 {
 	enum zone_type top_zone = ZONE_NORMAL;
 	int i;

 #ifdef CONFIG_HIGHMEM
 	top_zone = ZONE_HIGHMEM;
 #endif

 	for (i = top_zone; i >= 0; i--) {
 		if (max_zone_pfns[i] <= pfn_limit)
 			return i;
 	}

 	return -EPERM;
 }

 /*
  * paging_init() sets up the page tables - in fact we've already done this.
  */
 void __init paging_init(void)
 {
 	unsigned long long total_ram = memblock_phys_mem_size();
 	phys_addr_t top_of_ram = memblock_end_of_DRAM();
 	enum zone_type top_zone;

 #ifdef CONFIG_PPC32
 	unsigned long v = __fix_to_virt(__end_of_fixed_addresses - 1);
 	unsigned long end = __fix_to_virt(FIX_HOLE);

 	for (; v < end; v += PAGE_SIZE)
 		map_page(v, 0, 0); /* XXX gross */
 #endif

 #ifdef CONFIG_HIGHMEM
 	map_page(PKMAP_BASE, 0, 0);	/* XXX gross */
 	pkmap_page_table = virt_to_kpte(PKMAP_BASE);

 	kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
 	kmap_prot = PAGE_KERNEL;
 #endif /* CONFIG_HIGHMEM */

 	printk(KERN_DEBUG "Top of RAM: 0x%llx, Total RAM: 0x%llx\n",
 	       (unsigned long long)top_of_ram, total_ram);
 	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
 	       (long int)((top_of_ram - total_ram) >> 20));

 #ifdef CONFIG_HIGHMEM
 	top_zone = ZONE_HIGHMEM;
 	limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT);
 #else
 	top_zone = ZONE_NORMAL;
 #endif

 	limit_zone_pfn(top_zone, top_of_ram >> PAGE_SHIFT);
 	zone_limits_final = true;
 	free_area_init_nodes(max_zone_pfns);

 	mark_nonram_nosave();
 }

 void __init mem_init(void)
 {
 	/*
 	 * book3s is limited to 16 page sizes due to encoding this in
 	 * a 4-bit field for slices.
 	 */
 	BUILD_BUG_ON(MMU_PAGE_COUNT > 16);

 #ifdef CONFIG_SWIOTLB
 	swiotlb_init(0);
 #endif

 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 	set_max_mapnr(max_pfn);
 	free_all_bootmem();

 #ifdef CONFIG_HIGHMEM
 	{
 		unsigned long pfn, highmem_mapnr;

 		highmem_mapnr = lowmem_end_addr >> PAGE_SHIFT;
 		for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
 			phys_addr_t paddr = (phys_addr_t)pfn << PAGE_SHIFT;
 			struct page *page = pfn_to_page(pfn);
 			if (!memblock_is_reserved(paddr))
 				free_highmem_page(page);
 		}
 	}
 #endif /* CONFIG_HIGHMEM */

 #if defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_SMP)
 	/*
 	 * If smp is enabled, next_tlbcam_idx is initialized in the cpu up
 	 * functions.... do it here for the non-smp case.
 	 */
 	per_cpu(next_tlbcam_idx, smp_processor_id()) =
 		(mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
 #endif

 	mem_init_print_info(NULL);
 #ifdef CONFIG_PPC32
 	pr_info("Kernel virtual memory layout:\n");
 	pr_info("  * 0x%08lx..0x%08lx  : fixmap\n", FIXADDR_START, FIXADDR_TOP);
 #ifdef CONFIG_HIGHMEM
 	pr_info("  * 0x%08lx..0x%08lx  : highmem PTEs\n",
 		PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
 #endif /* CONFIG_HIGHMEM */
 #ifdef CONFIG_NOT_COHERENT_CACHE
 	pr_info("  * 0x%08lx..0x%08lx  : consistent mem\n",
 		IOREMAP_TOP, IOREMAP_TOP + CONFIG_CONSISTENT_SIZE);
 #endif /* CONFIG_NOT_COHERENT_CACHE */
 	pr_info("  * 0x%08lx..0x%08lx  : early ioremap\n",
 		ioremap_bot, IOREMAP_TOP);
 	pr_info("  * 0x%08lx..0x%08lx  : vmalloc & ioremap\n",
 		VMALLOC_START, VMALLOC_END);
 #endif /* CONFIG_PPC32 */
 }

 void free_initmem(void)
 {
 	ppc_md.progress = ppc_printk_progress;
 	free_initmem_default(POISON_FREE_INITMEM);
 }

 #ifdef CONFIG_BLK_DEV_INITRD
 void __init free_initrd_mem(unsigned long start, unsigned long end)
 {
 	free_reserved_area((void *)start, (void *)end, -1, "initrd");
 }
 #endif

 /*
  * This is called when a page has been modified by the kernel.
  * It just marks the page as not i-cache clean.  We do the i-cache
  * flush later when the page is given to a user process, if necessary.
  */
 void flush_dcache_page(struct page *page)
 {
 	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 		return;
 	/* avoid an atomic op if possible */
 	if (test_bit(PG_arch_1, &page->flags))
 		clear_bit(PG_arch_1, &page->flags);
 }
 EXPORT_SYMBOL(flush_dcache_page);

 void flush_dcache_icache_page(struct page *page)
 {
 #ifdef CONFIG_HUGETLB_PAGE
 	if (PageCompound(page)) {
 		flush_dcache_icache_hugepage(page);
 		return;
 	}
 #endif
 #if defined(CONFIG_8xx) || defined(CONFIG_PPC64)
 	/* On 8xx there is no need to kmap since highmem is not supported */
 	__flush_dcache_icache(page_address(page));
 #else
 	if (IS_ENABLED(CONFIG_BOOKE) || sizeof(phys_addr_t) > sizeof(void *)) {
 		void *start = kmap_atomic(page);
 		__flush_dcache_icache(start);
 		kunmap_atomic(start);
 	} else {
 		__flush_dcache_icache_phys(page_to_pfn(page) << PAGE_SHIFT);
 	}
 #endif
 }
 EXPORT_SYMBOL(flush_dcache_icache_page);

 void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
 {
 	clear_page(page);

 	/*
 	 * We shouldn't have to do this, but some versions of glibc
 	 * require it (ld.so assumes zero filled pages are icache clean)
 	 * - Anton
 	 */
 	flush_dcache_page(pg);
 }
 EXPORT_SYMBOL(clear_user_page);

 void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 		    struct page *pg)
 {
 	copy_page(vto, vfrom);

 	/*
 	 * We should be able to use the following optimisation, however
 	 * there are two problems.
 	 * Firstly a bug in some versions of binutils meant PLT sections
 	 * were not marked executable.
 	 * Secondly the first word in the GOT section is blrl, used
 	 * to establish the GOT address. Until recently the GOT was
 	 * not marked executable.
 	 * - Anton
 	 */
 #if 0
 	if (!vma->vm_file && ((vma->vm_flags & VM_EXEC) == 0))
 		return;
 #endif

 	flush_dcache_page(pg);
 }

 void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 			     unsigned long addr, int len)
 {
 	unsigned long maddr;

 	maddr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
 	flush_icache_range(maddr, maddr + len);
 	kunmap(page);
 }
 EXPORT_SYMBOL(flush_icache_user_range);

 /*
  * This is called at the end of handling a user page fault, when the
  * fault has been handled by updating a PTE in the linux page tables.
  * We use it to preload an HPTE into the hash table corresponding to
  * the updated linux PTE.
  *
  * This must always be called with the pte lock held.
  */
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 		      pte_t *ptep)
 {
 #ifdef CONFIG_PPC_STD_MMU
 	/*
 	 * We don't need to worry about _PAGE_PRESENT here because we are
 	 * called with either mm->page_table_lock held or ptl lock held
 	 */
 	unsigned long access = 0, trap;

 	/* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
 	if (!pte_young(*ptep) || address >= TASK_SIZE)
 		return;

 	/* We try to figure out if we are coming from an instruction
 	 * access fault and pass that down to __hash_page so we avoid
 	 * double-faulting on execution of fresh text. We have to test
 	 * for regs NULL since init will get here first thing at boot
 	 *
 	 * We also avoid filling the hash if not coming from a fault
 	 */
 	if (current->thread.regs == NULL)
 		return;
 	trap = TRAP(current->thread.regs);
 	if (trap == 0x400)
 		access |= _PAGE_EXEC;
 	else if (trap != 0x300)
 		return;
 	hash_preload(vma->vm_mm, address, access, trap);
 #endif /* CONFIG_PPC_STD_MMU */
 #if (defined(CONFIG_PPC_BOOK3E_64) || defined(CONFIG_PPC_FSL_BOOK3E)) \
 	&& defined(CONFIG_HUGETLB_PAGE)
 	if (is_vm_hugetlb_page(vma))
 		book3e_hugetlb_preload(vma, address, *ptep);
 #endif
 }

 /*
  * System memory should not be in /proc/iomem but various tools expect it
  * (eg kdump).
  */
 static int __init add_system_ram_resources(void)
 {
 	struct memblock_region *reg;

 	for_each_memblock(memory, reg) {
 		struct resource *res;
 		unsigned long base = reg->base;
 		unsigned long size = reg->size;

 		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
 		WARN_ON(!res);

 		if (res) {
 			res->name = "System RAM";
 			res->start = base;
 			res->end = base + size - 1;
 			res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 			WARN_ON(request_resource(&iomem_resource, res) < 0);
 		}
 	}

 	return 0;
 }
 subsys_initcall(add_system_ram_resources);

 #ifdef CONFIG_STRICT_DEVMEM
 /*
  * devmem_is_allowed(): check to see if /dev/mem access to a certain address
  * is valid. The argument is a physical page number.
  *
  * Access has to be given to non-kernel-ram areas as well, these contain the
  * PCI mmio resources as well as potential bios/acpi data regions.
  */
 int devmem_is_allowed(unsigned long pfn)
 {
 	if (page_is_rtas_user_buf(pfn))
 		return 1;
 	if (iomem_is_exclusive(PFN_PHYS(pfn)))
 		return 0;
 	if (!page_is_ram(pfn))
 		return 1;
 	return 0;
 }
 #endif /* CONFIG_STRICT_DEVMEM */
	/*
	* PowerPC version
	* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
	*
	* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
	* and Cort Dougan (PReP) (cort@cs.nmt.edu)
	* Copyright (C) 1996 Paul Mackerras
	* PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
	*
	* Derived from "arch/i386/mm/init.c"
	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	*
	* 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; either version
	* 2 of the License, or (at your option) any later version.
	*
	*/

	#include <linux/export.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/string.h>
	#include <linux/gfp.h>
	#include <linux/types.h>
	#include <linux/mm.h>
	#include <linux/stddef.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/highmem.h>
	#include <linux/initrd.h>
	#include <linux/pagemap.h>
	#include <linux/suspend.h>
	#include <linux/memblock.h>
	#include <linux/hugetlb.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>

	#include <asm/pgalloc.h>
	#include <asm/prom.h>
	#include <asm/io.h>
	#include <asm/mmu_context.h>
	#include <asm/pgtable.h>
	#include <asm/mmu.h>
	#include <asm/smp.h>
	#include <asm/machdep.h>
	#include <asm/btext.h>
	#include <asm/tlb.h>
	#include <asm/sections.h>
	#include <asm/sparsemem.h>
	#include <asm/vdso.h>
	#include <asm/fixmap.h>
	#include <asm/swiotlb.h>
	#include <asm/rtas.h>

	#include "mmu_decl.h"

	#ifndef CPU_FTR_COHERENT_ICACHE
	#define CPU_FTR_COHERENT_ICACHE 0 /* XXX for now */
	#define CPU_FTR_NOEXECUTE 0
	#endif

	unsigned long long memory_limit;

	#ifdef CONFIG_HIGHMEM
	pte_t *kmap_pte;
	EXPORT_SYMBOL(kmap_pte);
	pgprot_t kmap_prot;
	EXPORT_SYMBOL(kmap_prot);

	static inline pte_t *virt_to_kpte(unsigned long vaddr)
	{
	return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
	vaddr), vaddr), vaddr);
	}
	#endif

	int page_is_ram(unsigned long pfn)
	{
	#ifndef CONFIG_PPC64 /* XXX for now */
	return pfn < max_pfn;
	#else
	unsigned long paddr = (pfn << PAGE_SHIFT);
	struct memblock_region *reg;

	for_each_memblock(memory, reg)
	if (paddr >= reg->base && paddr < (reg->base + reg->size))
	return 1;
	return 0;
	#endif
	}

	pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
	unsigned long size, pgprot_t vma_prot)
	{
	if (ppc_md.phys_mem_access_prot)
	return ppc_md.phys_mem_access_prot(file, pfn, size, vma_prot);

	if (!page_is_ram(pfn))
	vma_prot = pgprot_noncached(vma_prot);

	return vma_prot;
	}
	EXPORT_SYMBOL(phys_mem_access_prot);

	#ifdef CONFIG_MEMORY_HOTPLUG

	#ifdef CONFIG_NUMA
	int memory_add_physaddr_to_nid(u64 start)
	{
	return hot_add_scn_to_nid(start);
	}
	#endif

	int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
	{
	struct pglist_data *pgdata;
	struct zone *zone;
	unsigned long start_pfn = start >> PAGE_SHIFT;
	unsigned long nr_pages = size >> PAGE_SHIFT;

	pgdata = NODE_DATA(nid);

	start = (unsigned long)__va(start);
	if (create_section_mapping(start, start + size))
	return -EINVAL;

	/* this should work for most non-highmem platforms */
	zone = pgdata->node_zones +
	zone_for_memory(nid, start, size, 0, for_device);

	return __add_pages(nid, zone, start_pfn, nr_pages);
	}

	#ifdef CONFIG_MEMORY_HOTREMOVE
	int arch_remove_memory(u64 start, u64 size)
	{
	unsigned long start_pfn = start >> PAGE_SHIFT;
	unsigned long nr_pages = size >> PAGE_SHIFT;
	struct zone *zone;
	int ret;

	zone = page_zone(pfn_to_page(start_pfn));
	ret = __remove_pages(zone, start_pfn, nr_pages);
	if (ret)
	return ret;

	/* Remove htab bolted mappings for this section of memory */
	start = (unsigned long)__va(start);
	ret = remove_section_mapping(start, start + size);

	/* Ensure all vmalloc mappings are flushed in case they also
	* hit that section of memory
	*/
	vm_unmap_aliases();

	return ret;
	}
	#endif
	#endif /* CONFIG_MEMORY_HOTPLUG */

	/*
	* walk_memory_resource() needs to make sure there is no holes in a given
	* memory range. PPC64 does not maintain the memory layout in /proc/iomem.
	* Instead it maintains it in memblock.memory structures. Walk through the
	* memory regions, find holes and callback for contiguous regions.
	*/
	int
	walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
	void arg, int (func)(unsigned long, unsigned long, void *))
	{
	struct memblock_region *reg;
	unsigned long end_pfn = start_pfn + nr_pages;
	unsigned long tstart, tend;
	int ret = -1;

	for_each_memblock(memory, reg) {
	tstart = max(start_pfn, memblock_region_memory_base_pfn(reg));
	tend = min(end_pfn, memblock_region_memory_end_pfn(reg));
	if (tstart >= tend)
	continue;
	ret = (*func)(tstart, tend - tstart, arg);
	if (ret)
	break;
	}
	return ret;
	}
	EXPORT_SYMBOL_GPL(walk_system_ram_range);

	#ifndef CONFIG_NEED_MULTIPLE_NODES
	void __init initmem_init(void)
	{
	max_low_pfn = max_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
	min_low_pfn = MEMORY_START >> PAGE_SHIFT;
	#ifdef CONFIG_HIGHMEM
	max_low_pfn = lowmem_end_addr >> PAGE_SHIFT;
	#endif

	/* Place all memblock_regions in the same node and merge contiguous
	* memblock_regions
	*/
	memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0);

	/* XXX need to clip this if using highmem? */
	sparse_memory_present_with_active_regions(0);
	sparse_init();
	}

	/* mark pages that don't exist as nosave */
	static int __init mark_nonram_nosave(void)
	{
	struct memblock_region reg, prev = NULL;

	for_each_memblock(memory, reg) {
	if (prev &&
	memblock_region_memory_end_pfn(prev) < memblock_region_memory_base_pfn(reg))
	register_nosave_region(memblock_region_memory_end_pfn(prev),
	memblock_region_memory_base_pfn(reg));
	prev = reg;
	}
	return 0;
	}
	#else /* CONFIG_NEED_MULTIPLE_NODES */
	static int __init mark_nonram_nosave(void)
	{
	return 0;
	}
	#endif

	static bool zone_limits_final;

	static unsigned long max_zone_pfns[MAX_NR_ZONES] = {
	[0 ... MAX_NR_ZONES - 1] = ~0UL
	};

	/*
	* Restrict the specified zone and all more restrictive zones
	* to be below the specified pfn. May not be called after
	* paging_init().
	*/
	void __init limit_zone_pfn(enum zone_type zone, unsigned long pfn_limit)
	{
	int i;

	if (WARN_ON(zone_limits_final))
	return;

	for (i = zone; i >= 0; i--) {
	if (max_zone_pfns[i] > pfn_limit)
	max_zone_pfns[i] = pfn_limit;
	}
	}

	/*
	* Find the least restrictive zone that is entirely below the
	* specified pfn limit. Returns < 0 if no suitable zone is found.
	*
	* pfn_limit must be u64 because it can exceed 32 bits even on 32-bit
	* systems -- the DMA limit can be higher than any possible real pfn.
	*/
	int dma_pfn_limit_to_zone(u64 pfn_limit)
	{
	enum zone_type top_zone = ZONE_NORMAL;
	int i;

	#ifdef CONFIG_HIGHMEM
	top_zone = ZONE_HIGHMEM;
	#endif

	for (i = top_zone; i >= 0; i--) {
	if (max_zone_pfns[i] <= pfn_limit)
	return i;
	}

	return -EPERM;
	}

	/*
	* paging_init() sets up the page tables - in fact we've already done this.
	*/
	void __init paging_init(void)
	{
	unsigned long long total_ram = memblock_phys_mem_size();
	phys_addr_t top_of_ram = memblock_end_of_DRAM();
	enum zone_type top_zone;

	#ifdef CONFIG_PPC32
	unsigned long v = __fix_to_virt(__end_of_fixed_addresses - 1);
	unsigned long end = __fix_to_virt(FIX_HOLE);

	for (; v < end; v += PAGE_SIZE)
	map_page(v, 0, 0); /* XXX gross */
	#endif

	#ifdef CONFIG_HIGHMEM
	map_page(PKMAP_BASE, 0, 0); /* XXX gross */
	pkmap_page_table = virt_to_kpte(PKMAP_BASE);

	kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
	kmap_prot = PAGE_KERNEL;
	#endif /* CONFIG_HIGHMEM */

	printk(KERN_DEBUG "Top of RAM: 0x%llx, Total RAM: 0x%llx\n",
	(unsigned long long)top_of_ram, total_ram);
	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
	(long int)((top_of_ram - total_ram) >> 20));

	#ifdef CONFIG_HIGHMEM
	top_zone = ZONE_HIGHMEM;
	limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT);
	#else
	top_zone = ZONE_NORMAL;
	#endif

	limit_zone_pfn(top_zone, top_of_ram >> PAGE_SHIFT);
	zone_limits_final = true;
	free_area_init_nodes(max_zone_pfns);

	mark_nonram_nosave();
	}

	void __init mem_init(void)
	{
	/*
	* book3s is limited to 16 page sizes due to encoding this in
	* a 4-bit field for slices.
	*/
	BUILD_BUG_ON(MMU_PAGE_COUNT > 16);

	#ifdef CONFIG_SWIOTLB
	swiotlb_init(0);
	#endif

	high_memory = (void ) __va(max_low_pfn PAGE_SIZE);
	set_max_mapnr(max_pfn);
	free_all_bootmem();

	#ifdef CONFIG_HIGHMEM
	{
	unsigned long pfn, highmem_mapnr;

	highmem_mapnr = lowmem_end_addr >> PAGE_SHIFT;
	for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
	phys_addr_t paddr = (phys_addr_t)pfn << PAGE_SHIFT;
	struct page *page = pfn_to_page(pfn);
	if (!memblock_is_reserved(paddr))
	free_highmem_page(page);
	}
	}
	#endif /* CONFIG_HIGHMEM */

	#if defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_SMP)
	/*
	* If smp is enabled, next_tlbcam_idx is initialized in the cpu up
	* functions.... do it here for the non-smp case.
	*/
	per_cpu(next_tlbcam_idx, smp_processor_id()) =
	(mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
	#endif

	mem_init_print_info(NULL);
	#ifdef CONFIG_PPC32
	pr_info("Kernel virtual memory layout:\n");
	pr_info(" * 0x%08lx..0x%08lx : fixmap\n", FIXADDR_START, FIXADDR_TOP);
	#ifdef CONFIG_HIGHMEM
	pr_info(" * 0x%08lx..0x%08lx : highmem PTEs\n",
	PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
	#endif /* CONFIG_HIGHMEM */
	#ifdef CONFIG_NOT_COHERENT_CACHE
	pr_info(" * 0x%08lx..0x%08lx : consistent mem\n",
	IOREMAP_TOP, IOREMAP_TOP + CONFIG_CONSISTENT_SIZE);
	#endif /* CONFIG_NOT_COHERENT_CACHE */
	pr_info(" * 0x%08lx..0x%08lx : early ioremap\n",
	ioremap_bot, IOREMAP_TOP);
	pr_info(" * 0x%08lx..0x%08lx : vmalloc & ioremap\n",
	VMALLOC_START, VMALLOC_END);
	#endif /* CONFIG_PPC32 */
	}

	void free_initmem(void)
	{
	ppc_md.progress = ppc_printk_progress;
	free_initmem_default(POISON_FREE_INITMEM);
	}

	#ifdef CONFIG_BLK_DEV_INITRD
	void __init free_initrd_mem(unsigned long start, unsigned long end)
	{
	free_reserved_area((void )start, (void )end, -1, "initrd");
	}
	#endif

	/*
	* This is called when a page has been modified by the kernel.
	* It just marks the page as not i-cache clean. We do the i-cache
	* flush later when the page is given to a user process, if necessary.
	*/
	void flush_dcache_page(struct page *page)
	{
	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
	return;
	/* avoid an atomic op if possible */
	if (test_bit(PG_arch_1, &page->flags))
	clear_bit(PG_arch_1, &page->flags);
	}
	EXPORT_SYMBOL(flush_dcache_page);

	void flush_dcache_icache_page(struct page *page)
	{
	#ifdef CONFIG_HUGETLB_PAGE
	if (PageCompound(page)) {
	flush_dcache_icache_hugepage(page);
	return;
	}
	#endif
	#if defined(CONFIG_8xx) \|\| defined(CONFIG_PPC64)
	/* On 8xx there is no need to kmap since highmem is not supported */
	__flush_dcache_icache(page_address(page));
	#else
	if (IS_ENABLED(CONFIG_BOOKE) \|\| sizeof(phys_addr_t) > sizeof(void *)) {
	void *start = kmap_atomic(page);
	__flush_dcache_icache(start);
	kunmap_atomic(start);
	} else {
	__flush_dcache_icache_phys(page_to_pfn(page) << PAGE_SHIFT);
	}
	#endif
	}
	EXPORT_SYMBOL(flush_dcache_icache_page);

	void clear_user_page(void page, unsigned long vaddr, struct page pg)
	{
	clear_page(page);

	/*
	* We shouldn't have to do this, but some versions of glibc
	* require it (ld.so assumes zero filled pages are icache clean)
	* - Anton
	*/
	flush_dcache_page(pg);
	}
	EXPORT_SYMBOL(clear_user_page);

	void copy_user_page(void vto, void vfrom, unsigned long vaddr,
	struct page *pg)
	{
	copy_page(vto, vfrom);

	/*
	* We should be able to use the following optimisation, however
	* there are two problems.
	* Firstly a bug in some versions of binutils meant PLT sections
	* were not marked executable.
	* Secondly the first word in the GOT section is blrl, used
	* to establish the GOT address. Until recently the GOT was
	* not marked executable.
	* - Anton
	*/
	#if 0
	if (!vma->vm_file && ((vma->vm_flags & VM_EXEC) == 0))
	return;
	#endif

	flush_dcache_page(pg);
	}

	void flush_icache_user_range(struct vm_area_struct vma, struct page page,
	unsigned long addr, int len)
	{
	unsigned long maddr;

	maddr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
	flush_icache_range(maddr, maddr + len);
	kunmap(page);
	}
	EXPORT_SYMBOL(flush_icache_user_range);

	/*
	* This is called at the end of handling a user page fault, when the
	* fault has been handled by updating a PTE in the linux page tables.
	* We use it to preload an HPTE into the hash table corresponding to
	* the updated linux PTE.
	*
	* This must always be called with the pte lock held.
	*/
	void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
	pte_t *ptep)
	{
	#ifdef CONFIG_PPC_STD_MMU
	/*
	* We don't need to worry about _PAGE_PRESENT here because we are
	* called with either mm->page_table_lock held or ptl lock held
	*/
	unsigned long access = 0, trap;

	/* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
	if (!pte_young(*ptep) \|\| address >= TASK_SIZE)
	return;

	/* We try to figure out if we are coming from an instruction
	* access fault and pass that down to __hash_page so we avoid
	* double-faulting on execution of fresh text. We have to test
	* for regs NULL since init will get here first thing at boot
	*
	* We also avoid filling the hash if not coming from a fault
	*/
	if (current->thread.regs == NULL)
	return;
	trap = TRAP(current->thread.regs);
	if (trap == 0x400)
	access \|= _PAGE_EXEC;
	else if (trap != 0x300)
	return;
	hash_preload(vma->vm_mm, address, access, trap);
	#endif /* CONFIG_PPC_STD_MMU */
	#if (defined(CONFIG_PPC_BOOK3E_64) \|\| defined(CONFIG_PPC_FSL_BOOK3E)) \
	&& defined(CONFIG_HUGETLB_PAGE)
	if (is_vm_hugetlb_page(vma))
	book3e_hugetlb_preload(vma, address, *ptep);
	#endif
	}

	/*
	* System memory should not be in /proc/iomem but various tools expect it
	* (eg kdump).
	*/
	static int __init add_system_ram_resources(void)
	{
	struct memblock_region *reg;

	for_each_memblock(memory, reg) {
	struct resource *res;
	unsigned long base = reg->base;
	unsigned long size = reg->size;

	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
	WARN_ON(!res);

	if (res) {
	res->name = "System RAM";
	res->start = base;
	res->end = base + size - 1;
	res->flags = IORESOURCE_MEM \| IORESOURCE_BUSY;
	WARN_ON(request_resource(&iomem_resource, res) < 0);
	}
	}

	return 0;
	}
	subsys_initcall(add_system_ram_resources);

	#ifdef CONFIG_STRICT_DEVMEM
	/*
	* devmem_is_allowed(): check to see if /dev/mem access to a certain address
	* is valid. The argument is a physical page number.
	*
	* Access has to be given to non-kernel-ram areas as well, these contain the
	* PCI mmio resources as well as potential bios/acpi data regions.
	*/
	int devmem_is_allowed(unsigned long pfn)
	{
	if (page_is_rtas_user_buf(pfn))
	return 1;
	if (iomem_is_exclusive(PFN_PHYS(pfn)))
	return 0;
	if (!page_is_ram(pfn))
	return 1;
	return 0;
	}
	#endif /* CONFIG_STRICT_DEVMEM */