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vmem.c

/*
 *  arch/s390/mm/vmem.c
 *
 *    Copyright IBM Corp. 2006
 *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#include <linux/bootmem.h>
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/hugetlb.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>

static DEFINE_MUTEX(vmem_mutex);

struct memory_segment {
      struct list_head list;
      unsigned long start;
      unsigned long size;
};

static LIST_HEAD(mem_segs);

static void __ref *vmem_alloc_pages(unsigned int order)
{
      if (slab_is_available())
            return (void *)__get_free_pages(GFP_KERNEL, order);
      return alloc_bootmem_pages((1 << order) * PAGE_SIZE);
}

static inline pud_t *vmem_pud_alloc(void)
{
      pud_t *pud = NULL;

#ifdef CONFIG_64BIT
      pud = vmem_alloc_pages(2);
      if (!pud)
            return NULL;
      clear_table((unsigned long *) pud, _REGION3_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
      return pud;
}

static inline pmd_t *vmem_pmd_alloc(void)
{
      pmd_t *pmd = NULL;

#ifdef CONFIG_64BIT
      pmd = vmem_alloc_pages(2);
      if (!pmd)
            return NULL;
      clear_table((unsigned long *) pmd, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
      return pmd;
}

static pte_t __ref *vmem_pte_alloc(void)
{
      pte_t *pte;

      if (slab_is_available())
            pte = (pte_t *) page_table_alloc(&init_mm);
      else
            pte = alloc_bootmem(PTRS_PER_PTE * sizeof(pte_t));
      if (!pte)
            return NULL;
      clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY,
                PTRS_PER_PTE * sizeof(pte_t));
      return pte;
}

/*
 * Add a physical memory range to the 1:1 mapping.
 */
static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
{
      unsigned long address;
      pgd_t *pg_dir;
      pud_t *pu_dir;
      pmd_t *pm_dir;
      pte_t *pt_dir;
      pte_t  pte;
      int ret = -ENOMEM;

      for (address = start; address < start + size; address += PAGE_SIZE) {
            pg_dir = pgd_offset_k(address);
            if (pgd_none(*pg_dir)) {
                  pu_dir = vmem_pud_alloc();
                  if (!pu_dir)
                        goto out;
                  pgd_populate_kernel(&init_mm, pg_dir, pu_dir);
            }

            pu_dir = pud_offset(pg_dir, address);
            if (pud_none(*pu_dir)) {
                  pm_dir = vmem_pmd_alloc();
                  if (!pm_dir)
                        goto out;
                  pud_populate_kernel(&init_mm, pu_dir, pm_dir);
            }

            pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
            pm_dir = pmd_offset(pu_dir, address);

#ifdef __s390x__
            if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&
                (address + HPAGE_SIZE <= start + size) &&
                (address >= HPAGE_SIZE)) {
                  pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
                  pmd_val(*pm_dir) = pte_val(pte);
                  address += HPAGE_SIZE - PAGE_SIZE;
                  continue;
            }
#endif
            if (pmd_none(*pm_dir)) {
                  pt_dir = vmem_pte_alloc();
                  if (!pt_dir)
                        goto out;
                  pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
            }

            pt_dir = pte_offset_kernel(pm_dir, address);
            *pt_dir = pte;
      }
      ret = 0;
out:
      flush_tlb_kernel_range(start, start + size);
      return ret;
}

/*
 * Remove a physical memory range from the 1:1 mapping.
 * Currently only invalidates page table entries.
 */
static void vmem_remove_range(unsigned long start, unsigned long size)
{
      unsigned long address;
      pgd_t *pg_dir;
      pud_t *pu_dir;
      pmd_t *pm_dir;
      pte_t *pt_dir;
      pte_t  pte;

      pte_val(pte) = _PAGE_TYPE_EMPTY;
      for (address = start; address < start + size; address += PAGE_SIZE) {
            pg_dir = pgd_offset_k(address);
            pu_dir = pud_offset(pg_dir, address);
            if (pud_none(*pu_dir))
                  continue;
            pm_dir = pmd_offset(pu_dir, address);
            if (pmd_none(*pm_dir))
                  continue;

            if (pmd_huge(*pm_dir)) {
                  pmd_clear_kernel(pm_dir);
                  address += HPAGE_SIZE - PAGE_SIZE;
                  continue;
            }

            pt_dir = pte_offset_kernel(pm_dir, address);
            *pt_dir = pte;
      }
      flush_tlb_kernel_range(start, start + size);
}

/*
 * Add a backed mem_map array to the virtual mem_map array.
 */
int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
{
      unsigned long address, start_addr, end_addr;
      pgd_t *pg_dir;
      pud_t *pu_dir;
      pmd_t *pm_dir;
      pte_t *pt_dir;
      pte_t  pte;
      int ret = -ENOMEM;

      start_addr = (unsigned long) start;
      end_addr = (unsigned long) (start + nr);

      for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
            pg_dir = pgd_offset_k(address);
            if (pgd_none(*pg_dir)) {
                  pu_dir = vmem_pud_alloc();
                  if (!pu_dir)
                        goto out;
                  pgd_populate_kernel(&init_mm, pg_dir, pu_dir);
            }

            pu_dir = pud_offset(pg_dir, address);
            if (pud_none(*pu_dir)) {
                  pm_dir = vmem_pmd_alloc();
                  if (!pm_dir)
                        goto out;
                  pud_populate_kernel(&init_mm, pu_dir, pm_dir);
            }

            pm_dir = pmd_offset(pu_dir, address);
            if (pmd_none(*pm_dir)) {
                  pt_dir = vmem_pte_alloc();
                  if (!pt_dir)
                        goto out;
                  pmd_populate_kernel(&init_mm, pm_dir, pt_dir);
            }

            pt_dir = pte_offset_kernel(pm_dir, address);
            if (pte_none(*pt_dir)) {
                  unsigned long new_page;

                  new_page =__pa(vmem_alloc_pages(0));
                  if (!new_page)
                        goto out;
                  pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
                  *pt_dir = pte;
            }
      }
      memset(start, 0, nr * sizeof(struct page));
      ret = 0;
out:
      flush_tlb_kernel_range(start_addr, end_addr);
      return ret;
}

/*
 * Add memory segment to the segment list if it doesn't overlap with
 * an already present segment.
 */
static int insert_memory_segment(struct memory_segment *seg)
{
      struct memory_segment *tmp;

      if (seg->start + seg->size > VMEM_MAX_PHYS ||
          seg->start + seg->size < seg->start)
            return -ERANGE;

      list_for_each_entry(tmp, &mem_segs, list) {
            if (seg->start >= tmp->start + tmp->size)
                  continue;
            if (seg->start + seg->size <= tmp->start)
                  continue;
            return -ENOSPC;
      }
      list_add(&seg->list, &mem_segs);
      return 0;
}

/*
 * Remove memory segment from the segment list.
 */
static void remove_memory_segment(struct memory_segment *seg)
{
      list_del(&seg->list);
}

static void __remove_shared_memory(struct memory_segment *seg)
{
      remove_memory_segment(seg);
      vmem_remove_range(seg->start, seg->size);
}

int vmem_remove_mapping(unsigned long start, unsigned long size)
{
      struct memory_segment *seg;
      int ret;

      mutex_lock(&vmem_mutex);

      ret = -ENOENT;
      list_for_each_entry(seg, &mem_segs, list) {
            if (seg->start == start && seg->size == size)
                  break;
      }

      if (seg->start != start || seg->size != size)
            goto out;

      ret = 0;
      __remove_shared_memory(seg);
      kfree(seg);
out:
      mutex_unlock(&vmem_mutex);
      return ret;
}

int vmem_add_mapping(unsigned long start, unsigned long size)
{
      struct memory_segment *seg;
      int ret;

      mutex_lock(&vmem_mutex);
      ret = -ENOMEM;
      seg = kzalloc(sizeof(*seg), GFP_KERNEL);
      if (!seg)
            goto out;
      seg->start = start;
      seg->size = size;

      ret = insert_memory_segment(seg);
      if (ret)
            goto out_free;

      ret = vmem_add_mem(start, size, 0);
      if (ret)
            goto out_remove;
      goto out;

out_remove:
      __remove_shared_memory(seg);
out_free:
      kfree(seg);
out:
      mutex_unlock(&vmem_mutex);
      return ret;
}

/*
 * map whole physical memory to virtual memory (identity mapping)
 * we reserve enough space in the vmalloc area for vmemmap to hotplug
 * additional memory segments.
 */
void __init vmem_map_init(void)
{
      unsigned long ro_start, ro_end;
      unsigned long start, end;
      int i;

      INIT_LIST_HEAD(&init_mm.context.crst_list);
      INIT_LIST_HEAD(&init_mm.context.pgtable_list);
      init_mm.context.noexec = 0;
      ro_start = ((unsigned long)&_stext) & PAGE_MASK;
      ro_end = PFN_ALIGN((unsigned long)&_eshared);
      for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
            start = memory_chunk[i].addr;
            end = memory_chunk[i].addr + memory_chunk[i].size;
            if (start >= ro_end || end <= ro_start)
                  vmem_add_mem(start, end - start, 0);
            else if (start >= ro_start && end <= ro_end)
                  vmem_add_mem(start, end - start, 1);
            else if (start >= ro_start) {
                  vmem_add_mem(start, ro_end - start, 1);
                  vmem_add_mem(ro_end, end - ro_end, 0);
            } else if (end < ro_end) {
                  vmem_add_mem(start, ro_start - start, 0);
                  vmem_add_mem(ro_start, end - ro_start, 1);
            } else {
                  vmem_add_mem(start, ro_start - start, 0);
                  vmem_add_mem(ro_start, ro_end - ro_start, 1);
                  vmem_add_mem(ro_end, end - ro_end, 0);
            }
      }
}

/*
 * Convert memory chunk array to a memory segment list so there is a single
 * list that contains both r/w memory and shared memory segments.
 */
static int __init vmem_convert_memory_chunk(void)
{
      struct memory_segment *seg;
      int i;

      mutex_lock(&vmem_mutex);
      for (i = 0; i < MEMORY_CHUNKS; i++) {
            if (!memory_chunk[i].size)
                  continue;
            seg = kzalloc(sizeof(*seg), GFP_KERNEL);
            if (!seg)
                  panic("Out of memory...\n");
            seg->start = memory_chunk[i].addr;
            seg->size = memory_chunk[i].size;
            insert_memory_segment(seg);
      }
      mutex_unlock(&vmem_mutex);
      return 0;
}

core_initcall(vmem_convert_memory_chunk);

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