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init.c

/*
 * arch/xtensa/mm/init.c
 *
 * Derived from MIPS, PPC.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2005 Tensilica Inc.
 *
 * Chris Zankel   <chris@zankel.net>
 * Joe Taylor     <joe@tensilica.com, joetylr@yahoo.com>
 * Marc Gauthier
 * Kevin Chea
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/bootmem.h>
#include <linux/swap.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/slab.h>

#include <asm/pgtable.h>
#include <asm/bootparam.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>
#include <asm/page.h>
#include <asm/pgalloc.h>


DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

/* References to section boundaries */

extern char _ftext, _etext, _fdata, _edata, _rodata_end;
extern char __init_begin, __init_end;

/*
 * mem_reserve(start, end, must_exist)
 *
 * Reserve some memory from the memory pool.
 *
 * Parameters:
 *  start   Start of region,
 *  end           End of region,
 *  must_exist    Must exist in memory pool.
 *
 * Returns:
 *  0 (memory area couldn't be mapped)
 * -1 (success)
 */

int __init mem_reserve(unsigned long start, unsigned long end, int must_exist)
{
      int i;

      if (start == end)
            return 0;

      start = start & PAGE_MASK;
      end = PAGE_ALIGN(end);

      for (i = 0; i < sysmem.nr_banks; i++)
            if (start < sysmem.bank[i].end
                && end >= sysmem.bank[i].start)
                  break;

      if (i == sysmem.nr_banks) {
            if (must_exist)
                  printk (KERN_WARNING "mem_reserve: [0x%0lx, 0x%0lx) "
                        "not in any region!\n", start, end);
            return 0;
      }

      if (start > sysmem.bank[i].start) {
            if (end < sysmem.bank[i].end) {
                  /* split entry */
                  if (sysmem.nr_banks >= SYSMEM_BANKS_MAX)
                        panic("meminfo overflow\n");
                  sysmem.bank[sysmem.nr_banks].start = end;
                  sysmem.bank[sysmem.nr_banks].end = sysmem.bank[i].end;
                  sysmem.nr_banks++;
            }
            sysmem.bank[i].end = start;
      } else {
            if (end < sysmem.bank[i].end)
                  sysmem.bank[i].start = end;
            else {
                  /* remove entry */
                  sysmem.nr_banks--;
                  sysmem.bank[i].start = sysmem.bank[sysmem.nr_banks].start;
                  sysmem.bank[i].end   = sysmem.bank[sysmem.nr_banks].end;
            }
      }
      return -1;
}


/*
 * Initialize the bootmem system and give it all the memory we have available.
 */

void __init bootmem_init(void)
{
      unsigned long pfn;
      unsigned long bootmap_start, bootmap_size;
      int i;

      max_low_pfn = max_pfn = 0;
      min_low_pfn = ~0;

      for (i=0; i < sysmem.nr_banks; i++) {
            pfn = PAGE_ALIGN(sysmem.bank[i].start) >> PAGE_SHIFT;
            if (pfn < min_low_pfn)
                  min_low_pfn = pfn;
            pfn = PAGE_ALIGN(sysmem.bank[i].end - 1) >> PAGE_SHIFT;
            if (pfn > max_pfn)
                  max_pfn = pfn;
      }

      if (min_low_pfn > max_pfn)
            panic("No memory found!\n");

      max_low_pfn = max_pfn < MAX_MEM_PFN >> PAGE_SHIFT ?
            max_pfn : MAX_MEM_PFN >> PAGE_SHIFT;

      /* Find an area to use for the bootmem bitmap. */

      bootmap_size = bootmem_bootmap_pages(max_low_pfn) << PAGE_SHIFT;
      bootmap_start = ~0;

      for (i=0; i<sysmem.nr_banks; i++)
            if (sysmem.bank[i].end - sysmem.bank[i].start >= bootmap_size) {
                  bootmap_start = sysmem.bank[i].start;
                  break;
            }

      if (bootmap_start == ~0UL)
            panic("Cannot find %ld bytes for bootmap\n", bootmap_size);

      /* Reserve the bootmem bitmap area */

      mem_reserve(bootmap_start, bootmap_start + bootmap_size, 1);
      bootmap_size = init_bootmem_node(NODE_DATA(0), min_low_pfn,
                               bootmap_start >> PAGE_SHIFT,
                               max_low_pfn);

      /* Add all remaining memory pieces into the bootmem map */

      for (i=0; i<sysmem.nr_banks; i++)
            free_bootmem(sysmem.bank[i].start,
                       sysmem.bank[i].end - sysmem.bank[i].start);

}


void __init paging_init(void)
{
      unsigned long zones_size[MAX_NR_ZONES];
      int i;

      /* All pages are DMA-able, so we put them all in the DMA zone. */

      zones_size[ZONE_DMA] = max_low_pfn;
      for (i = 1; i < MAX_NR_ZONES; i++)
            zones_size[i] = 0;

#ifdef CONFIG_HIGHMEM
      zones_size[ZONE_HIGHMEM] = max_pfn - max_low_pfn;
#endif

      /* Initialize the kernel's page tables. */

      memset(swapper_pg_dir, 0, PAGE_SIZE);

      free_area_init(zones_size);
}

/*
 * Flush the mmu and reset associated register to default values.
 */

void __init init_mmu (void)
{
      /* Writing zeros to the <t>TLBCFG special registers ensure
       * that valid values exist in the register.  For existing
       * PGSZID<w> fields, zero selects the first element of the
       * page-size array.  For nonexistent PGSZID<w> fields, zero is
       * the best value to write.  Also, when changing PGSZID<w>
       * fields, the corresponding TLB must be flushed.
       */
      set_itlbcfg_register (0);
      set_dtlbcfg_register (0);
      flush_tlb_all ();

      /* Set rasid register to a known value. */

      set_rasid_register (ASID_USER_FIRST);

      /* Set PTEVADDR special register to the start of the page
       * table, which is in kernel mappable space (ie. not
       * statically mapped).  This register's value is undefined on
       * reset.
       */
      set_ptevaddr_register (PGTABLE_START);
}

/*
 * Initialize memory pages.
 */

void __init mem_init(void)
{
      unsigned long codesize, reservedpages, datasize, initsize;
      unsigned long highmemsize, tmp, ram;

      max_mapnr = num_physpages = max_low_pfn;
      high_memory = (void *) __va(max_mapnr << PAGE_SHIFT);
      highmemsize = 0;

#ifdef CONFIG_HIGHMEM
#error HIGHGMEM not implemented in init.c
#endif

      totalram_pages += free_all_bootmem();

      reservedpages = ram = 0;
      for (tmp = 0; tmp < max_low_pfn; tmp++) {
            ram++;
            if (PageReserved(mem_map+tmp))
                  reservedpages++;
      }

      codesize =  (unsigned long) &_etext - (unsigned long) &_ftext;
      datasize =  (unsigned long) &_edata - (unsigned long) &_fdata;
      initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;

      printk("Memory: %luk/%luk available (%ldk kernel code, %ldk reserved, "
             "%ldk data, %ldk init %ldk highmem)\n",
             (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
             ram << (PAGE_SHIFT-10),
             codesize >> 10,
             reservedpages << (PAGE_SHIFT-10),
             datasize >> 10,
             initsize >> 10,
             highmemsize >> 10);
}

void
free_reserved_mem(void *start, void *end)
{
      for (; start < end; start += PAGE_SIZE) {
            ClearPageReserved(virt_to_page(start));
            init_page_count(virt_to_page(start));
            free_page((unsigned long)start);
            totalram_pages++;
      }
}

#ifdef CONFIG_BLK_DEV_INITRD
extern int initrd_is_mapped;

void free_initrd_mem(unsigned long start, unsigned long end)
{
      if (initrd_is_mapped) {
            free_reserved_mem((void*)start, (void*)end);
            printk ("Freeing initrd memory: %ldk freed\n",(end-start)>>10);
      }
}
#endif

void free_initmem(void)
{
      free_reserved_mem(&__init_begin, &__init_end);
      printk("Freeing unused kernel memory: %dk freed\n",
             (&__init_end - &__init_begin) >> 10);
}

void show_mem(void)
{
      int i, free = 0, total = 0, reserved = 0;
      int shared = 0, cached = 0;

      printk("Mem-info:\n");
      show_free_areas();
      printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
      i = max_mapnr;
      while (i-- > 0) {
            total++;
            if (PageReserved(mem_map+i))
                  reserved++;
            else if (PageSwapCache(mem_map+i))
                  cached++;
            else if (!page_count(mem_map + i))
                  free++;
            else
                  shared += page_count(mem_map + i) - 1;
      }
      printk("%d pages of RAM\n", total);
      printk("%d reserved pages\n", reserved);
      printk("%d pages shared\n", shared);
      printk("%d pages swap cached\n",cached);
      printk("%d free pages\n", free);
}

struct kmem_cache *pgtable_cache __read_mostly;

static void pgd_ctor(void *addr, struct kmem_cache *cache, unsigned long flags)
{
      pte_t* ptep = (pte_t*)addr;
      int i;

      for (i = 0; i < 1024; i++, ptep++)
            pte_clear(NULL, 0, ptep);

}

void __init pgtable_cache_init(void)
{
      pgtable_cache = kmem_cache_create("pgd",
                  PAGE_SIZE, PAGE_SIZE,
                  SLAB_HWCACHE_ALIGN,
                  pgd_ctor);
}

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