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mem.c

/*
 * Copyright (C) 2000 - 2003 Jeff Dike (jdike@addtoit.com)
 * Licensed under the GPL
 */

#include "linux/stddef.h"
#include "linux/kernel.h"
#include "linux/mm.h"
#include "linux/bootmem.h"
#include "linux/swap.h"
#include "linux/highmem.h"
#include "linux/gfp.h"
#include "asm/page.h"
#include "asm/fixmap.h"
#include "asm/pgalloc.h"
#include "kern_util.h"
#include "as-layout.h"
#include "kern.h"
#include "mem_user.h"
#include "um_uaccess.h"
#include "os.h"
#include "linux/types.h"
#include "linux/string.h"
#include "init.h"
#include "kern_constants.h"

/* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
unsigned long *empty_zero_page = NULL;
/* allocated in paging_init and unchanged thereafter */
unsigned long *empty_bad_page = NULL;
pgd_t swapper_pg_dir[PTRS_PER_PGD];
unsigned long long highmem;
int kmalloc_ok = 0;

static unsigned long brk_end;

void unmap_physmem(void)
{
      os_unmap_memory((void *) brk_end, uml_reserved - brk_end);
}

static void map_cb(void *unused)
{
      map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
}

#ifdef CONFIG_HIGHMEM
static void setup_highmem(unsigned long highmem_start,
                    unsigned long highmem_len)
{
      struct page *page;
      unsigned long highmem_pfn;
      int i;

      highmem_pfn = __pa(highmem_start) >> PAGE_SHIFT;
      for(i = 0; i < highmem_len >> PAGE_SHIFT; i++){
            page = &mem_map[highmem_pfn + i];
            ClearPageReserved(page);
            init_page_count(page);
            __free_page(page);
      }
}
#endif

void __init mem_init(void)
{
      /* clear the zero-page */
      memset((void *) empty_zero_page, 0, PAGE_SIZE);

      /* Map in the area just after the brk now that kmalloc is about
       * to be turned on.
       */
      brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
      map_cb(NULL);
      initial_thread_cb(map_cb, NULL);
      free_bootmem(__pa(brk_end), uml_reserved - brk_end);
      uml_reserved = brk_end;

      /* this will put all low memory onto the freelists */
      totalram_pages = free_all_bootmem();
      max_low_pfn = totalram_pages;
#ifdef CONFIG_HIGHMEM
      totalhigh_pages = highmem >> PAGE_SHIFT;
      totalram_pages += totalhigh_pages;
#endif
      num_physpages = totalram_pages;
      max_pfn = totalram_pages;
      printk(KERN_INFO "Memory: %luk available\n", 
             (unsigned long) nr_free_pages() << (PAGE_SHIFT-10));
      kmalloc_ok = 1;

#ifdef CONFIG_HIGHMEM
      setup_highmem(end_iomem, highmem);
#endif
}

/*
 * Create a page table and place a pointer to it in a middle page
 * directory entry.
 */
static void __init one_page_table_init(pmd_t *pmd)
{
      if (pmd_none(*pmd)) {
            pte_t *pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
            set_pmd(pmd, __pmd(_KERNPG_TABLE +
                                 (unsigned long) __pa(pte)));
            if (pte != pte_offset_kernel(pmd, 0))
                  BUG();
      }
}

static void __init one_md_table_init(pud_t *pud)
{
#ifdef CONFIG_3_LEVEL_PGTABLES
      pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
      set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
      if (pmd_table != pmd_offset(pud, 0))
            BUG();
#endif
}

static void __init fixrange_init(unsigned long start, unsigned long end, 
                         pgd_t *pgd_base)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      int i, j;
      unsigned long vaddr;

      vaddr = start;
      i = pgd_index(vaddr);
      j = pmd_index(vaddr);
      pgd = pgd_base + i;

      for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
            pud = pud_offset(pgd, vaddr);
            if (pud_none(*pud))
                  one_md_table_init(pud);
            pmd = pmd_offset(pud, vaddr);
            for (; (j < PTRS_PER_PMD) && (vaddr != end); pmd++, j++) {
                  one_page_table_init(pmd);
                  vaddr += PMD_SIZE;
            }
            j = 0;
      }
}

#ifdef CONFIG_HIGHMEM
pte_t *kmap_pte;
pgprot_t kmap_prot;

#define kmap_get_fixmap_pte(vaddr)                          \
      pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)),\
                    (vaddr)), (vaddr))

static void __init kmap_init(void)
{
      unsigned long kmap_vstart;

      /* cache the first kmap pte */
      kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
      kmap_pte = kmap_get_fixmap_pte(kmap_vstart);

      kmap_prot = PAGE_KERNEL;
}

static void __init init_highmem(void)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      pte_t *pte;
      unsigned long vaddr;

      /*
       * Permanent kmaps:
       */
      vaddr = PKMAP_BASE;
      fixrange_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, swapper_pg_dir);

      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;

      kmap_init();
}
#endif /* CONFIG_HIGHMEM */

static void __init fixaddr_user_init( void)
{
#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
      long size = FIXADDR_USER_END - FIXADDR_USER_START;
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      pte_t *pte;
      unsigned long paddr, vaddr = FIXADDR_USER_START;

      if (  ! size )
            return;

      fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
      paddr = (unsigned long)alloc_bootmem_low_pages( size);
      memcpy( (void *)paddr, (void *)FIXADDR_USER_START, size);
      paddr = __pa(paddr);
      for ( ; size > 0; size-=PAGE_SIZE, vaddr+=PAGE_SIZE, paddr+=PAGE_SIZE){
            pgd = swapper_pg_dir + pgd_index(vaddr);
            pud = pud_offset(pgd, vaddr);
            pmd = pmd_offset(pud, vaddr);
            pte = pte_offset_kernel(pmd, vaddr);
            pte_set_val( (*pte), paddr, PAGE_READONLY);
      }
#endif
}

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

      empty_zero_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
      empty_bad_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
      for(i = 0; i < ARRAY_SIZE(zones_size); i++)
            zones_size[i] = 0;

      zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
            (uml_physmem >> PAGE_SHIFT);
#ifdef CONFIG_HIGHMEM
      zones_size[ZONE_HIGHMEM] = highmem >> PAGE_SHIFT;
#endif
      free_area_init(zones_size);

      /*
       * 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;
      fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);

      fixaddr_user_init();

#ifdef CONFIG_HIGHMEM
      init_highmem();
#endif
}

struct page *arch_validate(struct page *page, gfp_t mask, int order)
{
      unsigned long addr, zero = 0;
      int i;

 again:
      if(page == NULL)
            return page;
      if(PageHighMem(page))
            return page;

      addr = (unsigned long) page_address(page);
      for(i = 0; i < (1 << order); i++){
            current->thread.fault_addr = (void *) addr;
            if(__do_copy_to_user((void __user *) addr, &zero,
                             sizeof(zero),
                             &current->thread.fault_addr,
                             &current->thread.fault_catcher)){
                  if(!(mask & __GFP_WAIT))
                        return NULL;
                  else break;
            }
            addr += PAGE_SIZE;
      }

      if(i == (1 << order))
            return page;
      page = alloc_pages(mask, order);
      goto again;
}

/* This can't do anything because nothing in the kernel image can be freed
 * since it's not in kernel physical memory.
 */

void free_initmem(void)
{
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
      if (start < end)
            printk ("Freeing initrd memory: %ldk freed\n", 
                  (end - start) >> 10);
      for (; start < end; start += PAGE_SIZE) {
            ClearPageReserved(virt_to_page(start));
            init_page_count(virt_to_page(start));
            free_page(start);
            totalram_pages++;
      }
}
#endif

void show_mem(void)
{
      int pfn, total = 0, reserved = 0;
      int shared = 0, cached = 0;
      int highmem = 0;
      struct page *page;

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

/*
 * Allocate and free page tables.
 */

pgd_t *pgd_alloc(struct mm_struct *mm)
{
      pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);

      if (pgd) {
            memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
            memcpy(pgd + USER_PTRS_PER_PGD, 
                   swapper_pg_dir + USER_PTRS_PER_PGD, 
                   (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
      }
      return pgd;
}

void pgd_free(pgd_t *pgd)
{
      free_page((unsigned long) pgd);
}

pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
      pte_t *pte;

      pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
      return pte;
}

struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
      struct page *pte;

      pte = alloc_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
      return pte;
}

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