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 #include <linux/smp.h>
  19 
  20 #include <asm/system.h>
  21 #include <asm/segment.h>
  22 #include <asm/pgtable.h>
  23 
  24 /*
  25  * The SMP kernel can't handle the 4MB page table optimizations yet
  26  */
  27 #ifdef __SMP__
  28 #undef USE_PENTIUM_MM
  29 #endif
  30 
  31 extern void die_if_kernel(char *,struct pt_regs *,long);
  32 extern void show_net_buffers(void);
  33 
  34 /*
  35  * BAD_PAGE is the page that is used for page faults when linux
  36  * is out-of-memory. Older versions of linux just did a
  37  * do_exit(), but using this instead means there is less risk
  38  * for a process dying in kernel mode, possibly leaving a inode
  39  * unused etc..
  40  *
  41  * BAD_PAGETABLE is the accompanying page-table: it is initialized
  42  * to point to BAD_PAGE entries.
  43  *
  44  * ZERO_PAGE is a special page that is used for zero-initialized
  45  * data and COW.
  46  */
  47 pte_t * __bad_pagetable(void)
     /*  */
  48 {
  49         extern char empty_bad_page_table[PAGE_SIZE];
  50 
  51         __asm__ __volatile__("cld ; rep ; stosl":
  52                 :"a" (pte_val(BAD_PAGE)),
  53                  "D" ((long) empty_bad_page_table),
  54                  "c" (PAGE_SIZE/4)
  55                 :"di","cx");
  56         return (pte_t *) empty_bad_page_table;
  57 }
  58 
  59 pte_t __bad_page(void)
     /*  */
  60 {
  61         extern char empty_bad_page[PAGE_SIZE];
  62 
  63         __asm__ __volatile__("cld ; rep ; stosl":
  64                 :"a" (0),
  65                  "D" ((long) empty_bad_page),
  66                  "c" (PAGE_SIZE/4)
  67                 :"di","cx");
  68         return pte_mkdirty(mk_pte((unsigned long) empty_bad_page, PAGE_SHARED));
  69 }
  70 
  71 void show_mem(void)
     /*  */
  72 {
  73         int i,free = 0,total = 0,reserved = 0;
  74         int shared = 0;
  75 
  76         printk("Mem-info:\n");
  77         show_free_areas();
  78         printk("Free swap:       %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
  79         i = high_memory >> PAGE_SHIFT;
  80         while (i-- > 0) {
  81                 total++;
  82                 if (mem_map[i].reserved)
  83                         reserved++;
  84                 else if (!mem_map[i].count)
  85                         free++;
  86                 else
  87                         shared += mem_map[i].count-1;
  88         }
  89         printk("%d pages of RAM\n",total);
  90         printk("%d free pages\n",free);
  91         printk("%d reserved pages\n",reserved);
  92         printk("%d pages shared\n",shared);
  93         show_buffers();
  94 #ifdef CONFIG_NET
  95         show_net_buffers();
  96 #endif
  97 }
  98 
  99 extern unsigned long free_area_init(unsigned long, unsigned long);
 100 
 101 /*
 102  * paging_init() sets up the page tables - note that the first 4MB are
 103  * already mapped by head.S.
 104  *
 105  * This routines also unmaps the page at virtual kernel address 0, so
 106  * that we can trap those pesky NULL-reference errors in the kernel.
 107  */
 108 unsigned long paging_init(unsigned long start_mem, unsigned long end_mem)
     /*  */
 109 {
 110         pgd_t * pg_dir;
 111         pte_t * pg_table;
 112         unsigned long tmp;
 113         unsigned long address;
 114 
 115 /*
 116  * Physical page 0 is special; it's not touched by Linux since BIOS
 117  * and SMM (for laptops with [34]86/SL chips) may need it.  It is read
 118  * and write protected to detect null pointer references in the
 119  * kernel.
 120  * It may also hold the MP configuration table when we are booting SMP.
 121  */
 122 #if 0
 123         memset((void *) 0, 0, PAGE_SIZE);
 124 #endif
 125 #ifdef __SMP__
 126         smp_scan_config(0x0,0x400);     /* Scan the bottom 1K for a signature */
 127         /*
 128          *      FIXME: Linux assumes you have 640K of base ram.. this continues
 129          *      the error...
 130          */
 131         smp_scan_config(639*0x400,0x400);       /* Scan the top 1K of base RAM */
 132         smp_scan_config(0xF0000,0x10000);       /* Scan the 64K of bios */
 133         /*
 134          *      If it is an SMP machine we should know now, unless the configuration
 135          *      is in an EISA/MCA bus machine with an extended bios data area. I don't
 136          *      have such a machine so someone else can fill in the check of the EBDA
 137          *      here.
 138          */
 139 /*      smp_alloc_memory(8192); */
 140 #endif
 141 #ifdef TEST_VERIFY_AREA
 142         wp_works_ok = 0;
 143 #endif
 144         start_mem = PAGE_ALIGN(start_mem);
 145         address = 0;
 146         pg_dir = swapper_pg_dir;
 147         while (address < end_mem) {
 148 #ifdef USE_PENTIUM_MM
 149                 if (address <= end_mem + 4*1024*1024 &&
 150                     (x86_capability & 8)) {
 151 #ifdef GAS_KNOWS_CR4
 152                         __asm__("movl %%cr4,%%eax\n\t"
 153                                 "orl $16,%%eax\n\t"
 154                                 "movl %%eax,%%cr4"
 155                                 : : :"ax");
 156 #else
 157                         __asm__(".byte 0x0f,0x20,0xe0\n\t"
 158                                 "orl $16,%%eax\n\t"
 159                                 ".byte 0x0f,0x22,0xe0"
 160                                 : : :"ax");
 161 #endif
 162                         wp_works_ok = 1;
 163                         pgd_val(pg_dir[0]) = _PAGE_TABLE | _PAGE_4M | address;
 164                         pgd_val(pg_dir[768]) = _PAGE_TABLE | _PAGE_4M | address;
 165                         pg_dir++;
 166                         address += 4*1024*1024;
 167                         continue;
 168                 }
 169 #endif
 170                 /* map the memory at virtual addr 0xC0000000 */
 171                 pg_table = (pte_t *) (PAGE_MASK & pgd_val(pg_dir[768]));
 172                 if (!pg_table) {
 173                         pg_table = (pte_t *) start_mem;
 174                         start_mem += PAGE_SIZE;
 175                 }
 176 
 177                 /* also map it temporarily at 0x0000000 for init */
 178                 pgd_val(pg_dir[0])   = _PAGE_TABLE | (unsigned long) pg_table;
 179                 pgd_val(pg_dir[768]) = _PAGE_TABLE | (unsigned long) pg_table;
 180                 pg_dir++;
 181                 for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
 182                         if (address < end_mem)
 183                                 set_pte(pg_table, mk_pte(address, PAGE_SHARED));
 184                         else
 185                                 pte_clear(pg_table);
 186                         address += PAGE_SIZE;
 187                 }
 188         }
 189         invalidate();
 190         return free_area_init(start_mem, end_mem);
 191 }
 192 
 193 void mem_init(unsigned long start_mem, unsigned long end_mem)
     /*  */
 194 {
 195         unsigned long start_low_mem = PAGE_SIZE;
 196         int codepages = 0;
 197         int reservedpages = 0;
 198         int datapages = 0;
 199         unsigned long tmp;
 200         extern int _etext;
 201 
 202         end_mem &= PAGE_MASK;
 203         high_memory = end_mem;
 204 
 205         /* clear the zero-page */
 206         memset(empty_zero_page, 0, PAGE_SIZE);
 207 
 208         /* mark usable pages in the mem_map[] */
 209         start_low_mem = PAGE_ALIGN(start_low_mem);
 210 
 211 #ifdef __SMP__
 212         /*
 213          * But first pinch a few for the stack/trampoline stuff
 214          */
 215         start_low_mem += PAGE_SIZE;                             /* 32bit startup code */
 216         start_low_mem = smp_alloc_memory(start_low_mem);        /* AP processor stacks */
 217 #endif
 218         start_mem = PAGE_ALIGN(start_mem);
 219 
 220         /*
 221          * IBM messed up *AGAIN* in their thinkpad: 0xA0000 -> 0x9F000.
 222          * They seem to have done something stupid with the floppy
 223          * controller as well..
 224          */
 225         while (start_low_mem < 0x9f000) {
 226                 mem_map[MAP_NR(start_low_mem)].reserved = 0;
 227                 start_low_mem += PAGE_SIZE;
 228         }
 229 
 230         while (start_mem < high_memory) {
 231                 mem_map[MAP_NR(start_mem)].reserved = 0;
 232                 start_mem += PAGE_SIZE;
 233         }
 234         for (tmp = 0 ; tmp < high_memory ; tmp += PAGE_SIZE) {
 235                 if (mem_map[MAP_NR(tmp)].reserved) {
 236                         if (tmp >= 0xA0000 && tmp < 0x100000)
 237                                 reservedpages++;
 238                         else if (tmp < (unsigned long) &_etext)
 239                                 codepages++;
 240                         else
 241                                 datapages++;
 242                         continue;
 243                 }
 244                 mem_map[MAP_NR(tmp)].count = 1;
 245                 free_page(tmp);
 246         }
 247         tmp = nr_free_pages << PAGE_SHIFT;
 248         printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data)\n",
 249                 tmp >> 10,
 250                 high_memory >> 10,
 251                 codepages << (PAGE_SHIFT-10),
 252                 reservedpages << (PAGE_SHIFT-10),
 253                 datapages << (PAGE_SHIFT-10));
 254 /* test if the WP bit is honoured in supervisor mode */
 255         if (wp_works_ok < 0) {
 256                 pg0[0] = pte_val(mk_pte(0, PAGE_READONLY));
 257                 invalidate();
 258                 __asm__ __volatile__("movb 0,%%al ; movb %%al,0": : :"ax", "memory");
 259                 pg0[0] = 0;
 260                 invalidate();
 261                 if (wp_works_ok < 0)
 262                         wp_works_ok = 0;
 263         }
 264         return;
 265 }
 266 
 267 void si_meminfo(struct sysinfo *val)
     /*  */
 268 {
 269         int i;
 270 
 271         i = high_memory >> PAGE_SHIFT;
 272         val->totalram = 0;
 273         val->sharedram = 0;
 274         val->freeram = nr_free_pages << PAGE_SHIFT;
 275         val->bufferram = buffermem;
 276         while (i-- > 0)  {
 277                 if (mem_map[i].reserved)
 278                         continue;
 279                 val->totalram++;
 280                 if (!mem_map[i].count)
 281                         continue;
 282                 val->sharedram += mem_map[i].count-1;
 283         }
 284         val->totalram <<= PAGE_SHIFT;
 285         val->sharedram <<= PAGE_SHIFT;
 286         return;
 287 }
/* */
root/arch/i386/mm/init.c

DEFINITIONS
