arch/i386/mm/init.c

/* */
This source file includes following definitions.
__bad_pagetable
__bad_page
show_mem
paging_init
mem_init
si_meminfo
   1 /*
   2  *  linux/arch/i386/mm/init.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6 
   7 #include <linux/config.h>
   8 #include <linux/signal.h>
   9 #include <linux/sched.h>
  10 #include <linux/head.h>
  11 #include <linux/kernel.h>
  12 #include <linux/errno.h>
  13 #include <linux/string.h>
  14 #include <linux/types.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/mman.h>
  17 #include <linux/mm.h>
  18 
  19 #include <asm/system.h>
  20 #include <asm/segment.h>
  21 #include <asm/pgtable.h>
  22 
  23 extern void scsi_mem_init(unsigned long);
  24 extern void sound_mem_init(void);
  25 extern void die_if_kernel(char *,struct pt_regs *,long);
  26 extern void show_net_buffers(void);
  27 
  28 /*
  29  * BAD_PAGE is the page that is used for page faults when linux
  30  * is out-of-memory. Older versions of linux just did a
  31  * do_exit(), but using this instead means there is less risk
  32  * for a process dying in kernel mode, possibly leaving a inode
  33  * unused etc..
  34  *
  35  * BAD_PAGETABLE is the accompanying page-table: it is initialized
  36  * to point to BAD_PAGE entries.
  37  *
  38  * ZERO_PAGE is a special page that is used for zero-initialized
  39  * data and COW.
  40  */
  41 pte_t * __bad_pagetable(void)
     /*  */
  42 {
  43         extern char empty_bad_page_table[PAGE_SIZE];
  44 
  45         __asm__ __volatile__("cld ; rep ; stosl":
  46                 :"a" (pte_val(BAD_PAGE)),
  47                  "D" ((long) empty_bad_page_table),
  48                  "c" (PAGE_SIZE/4)
  49                 :"di","cx");
  50         return (pte_t *) empty_bad_page_table;
  51 }
  52 
  53 pte_t __bad_page(void)
     /*  */
  54 {
  55         extern char empty_bad_page[PAGE_SIZE];
  56 
  57         __asm__ __volatile__("cld ; rep ; stosl":
  58                 :"a" (0),
  59                  "D" ((long) empty_bad_page),
  60                  "c" (PAGE_SIZE/4)
  61                 :"di","cx");
  62         return pte_mkdirty(mk_pte((unsigned long) empty_bad_page, PAGE_SHARED));
  63 }
  64 
  65 void show_mem(void)
     /*  */
  66 {
  67         int i,free = 0,total = 0,reserved = 0;
  68         int shared = 0;
  69 
  70         printk("Mem-info:\n");
  71         show_free_areas();
  72         printk("Free swap:       %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
  73         i = high_memory >> PAGE_SHIFT;
  74         while (i-- > 0) {
  75                 total++;
  76                 if (mem_map[i] & MAP_PAGE_RESERVED)
  77                         reserved++;
  78                 else if (!mem_map[i])
  79                         free++;
  80                 else
  81                         shared += mem_map[i]-1;
  82         }
  83         printk("%d pages of RAM\n",total);
  84         printk("%d free pages\n",free);
  85         printk("%d reserved pages\n",reserved);
  86         printk("%d pages shared\n",shared);
  87         show_buffers();
  88 #ifdef CONFIG_NET
  89         show_net_buffers();
  90 #endif
  91 }
  92 
  93 extern unsigned long free_area_init(unsigned long, unsigned long);
  94 
  95 /*
  96  * paging_init() sets up the page tables - note that the first 4MB are
  97  * already mapped by head.S.
  98  *
  99  * This routines also unmaps the page at virtual kernel address 0, so
 100  * that we can trap those pesky NULL-reference errors in the kernel.
 101  */
 102 unsigned long paging_init(unsigned long start_mem, unsigned long end_mem)
     /*  */
 103 {
 104         pgd_t * pg_dir;
 105         pte_t * pg_table;
 106         unsigned long tmp;
 107         unsigned long address;
 108 
 109 /*
 110  * Physical page 0 is special; it's not touched by Linux since BIOS
 111  * and SMM (for laptops with [34]86/SL chips) may need it.  It is read
 112  * and write protected to detect null pointer references in the
 113  * kernel.
 114  */
 115 #if 0
 116         memset((void *) 0, 0, PAGE_SIZE);
 117 #endif
 118         start_mem = PAGE_ALIGN(start_mem);
 119         address = 0;
 120         pg_dir = swapper_pg_dir;
 121         while (address < end_mem) {
 122                 /* map the memory at virtual addr 0xC0000000 */
 123                 pg_table = (pte_t *) (PAGE_MASK & pgd_val(pg_dir[768]));
 124                 if (!pg_table) {
 125                         pg_table = (pte_t *) start_mem;
 126                         start_mem += PAGE_SIZE;
 127                 }
 128 
 129                 /* also map it temporarily at 0x0000000 for init */
 130                 pgd_val(pg_dir[0])   = _PAGE_TABLE | (unsigned long) pg_table;
 131                 pgd_val(pg_dir[768]) = _PAGE_TABLE | (unsigned long) pg_table;
 132                 pg_dir++;
 133                 for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
 134                         if (address < end_mem)
 135                                 *pg_table = mk_pte(address, PAGE_SHARED);
 136                         else
 137                                 pte_clear(pg_table);
 138                         address += PAGE_SIZE;
 139                 }
 140         }
 141         invalidate();
 142         return free_area_init(start_mem, end_mem);
 143 }
 144 
 145 void mem_init(unsigned long start_mem, unsigned long end_mem)
     /*  */
 146 {
 147         unsigned long start_low_mem = PAGE_SIZE;
 148         int codepages = 0;
 149         int reservedpages = 0;
 150         int datapages = 0;
 151         unsigned long tmp;
 152         extern int _etext;
 153 
 154         end_mem &= PAGE_MASK;
 155         high_memory = end_mem;
 156 
 157         /* clear the zero-page */
 158         memset(empty_zero_page, 0, PAGE_SIZE);
 159 
 160         /* mark usable pages in the mem_map[] */
 161         start_low_mem = PAGE_ALIGN(start_low_mem);
 162         start_mem = PAGE_ALIGN(start_mem);
 163 
 164         /*
 165          * IBM messed up *AGAIN* in their thinkpad: 0xA0000 -> 0x9F000.
 166          * They seem to have done something stupid with the floppy
 167          * controller as well..
 168          */
 169         while (start_low_mem < 0x9f000) {
 170                 mem_map[MAP_NR(start_low_mem)] = 0;
 171                 start_low_mem += PAGE_SIZE;
 172         }
 173 
 174         while (start_mem < high_memory) {
 175                 mem_map[MAP_NR(start_mem)] = 0;
 176                 start_mem += PAGE_SIZE;
 177         }
 178 #ifdef CONFIG_SCSI
 179         scsi_mem_init(high_memory);
 180 #endif
 181 #ifdef CONFIG_SOUND
 182         sound_mem_init();
 183 #endif
 184         for (tmp = 0 ; tmp < high_memory ; tmp += PAGE_SIZE) {
 185                 if (mem_map[MAP_NR(tmp)]) {
 186                         if (tmp >= 0xA0000 && tmp < 0x100000)
 187                                 reservedpages++;
 188                         else if (tmp < (unsigned long) &_etext)
 189                                 codepages++;
 190                         else
 191                                 datapages++;
 192                         continue;
 193                 }
 194                 mem_map[MAP_NR(tmp)] = 1;
 195                 free_page(tmp);
 196         }
 197         tmp = nr_free_pages << PAGE_SHIFT;
 198         printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data)\n",
 199                 tmp >> 10,
 200                 high_memory >> 10,
 201                 codepages << (PAGE_SHIFT-10),
 202                 reservedpages << (PAGE_SHIFT-10),
 203                 datapages << (PAGE_SHIFT-10));
 204 /* test if the WP bit is honoured in supervisor mode */
 205         wp_works_ok = -1;
 206         pg0[0] = pte_val(mk_pte(0, PAGE_READONLY));
 207         invalidate();
 208         __asm__ __volatile__("movb 0,%%al ; movb %%al,0": : :"ax", "memory");
 209         pg0[0] = 0;
 210         invalidate();
 211         if (wp_works_ok < 0)
 212                 wp_works_ok = 0;
 213 #ifdef CONFIG_TEST_VERIFY_AREA
 214         wp_works_ok = 0;
 215 #endif
 216         return;
 217 }
 218 
 219 void si_meminfo(struct sysinfo *val)
     /*  */
 220 {
 221         int i;
 222 
 223         i = high_memory >> PAGE_SHIFT;
 224         val->totalram = 0;
 225         val->sharedram = 0;
 226         val->freeram = nr_free_pages << PAGE_SHIFT;
 227         val->bufferram = buffermem;
 228         while (i-- > 0)  {
 229                 if (mem_map[i] & MAP_PAGE_RESERVED)
 230                         continue;
 231                 val->totalram++;
 232                 if (!mem_map[i])
 233                         continue;
 234                 val->sharedram += mem_map[i]-1;
 235         }
 236         val->totalram <<= PAGE_SHIFT;
 237         val->sharedram <<= PAGE_SHIFT;
 238         return;
 239 }
/* */
root/arch/i386/mm/init.c

DEFINITIONS
