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/*
* linux/arch/i386/mm/init.c
*
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/head.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
extern void scsi_mem_init(unsigned long);
extern void sound_mem_init(void);
extern void die_if_kernel(char *,struct pt_regs *,long);
extern void show_net_buffers(void);
/*
* BAD_PAGE is the page that is used for page faults when linux
* is out-of-memory. Older versions of linux just did a
* do_exit(), but using this instead means there is less risk
* for a process dying in kernel mode, possibly leaving a inode
* unused etc..
*
* BAD_PAGETABLE is the accompanying page-table: it is initialized
* to point to BAD_PAGE entries.
*
* ZERO_PAGE is a special page that is used for zero-initialized
* data and COW.
*/
pte_t * __bad_pagetable(void)
{
extern char empty_bad_page_table[PAGE_SIZE];
__asm__ __volatile__("cld ; rep ; stosl":
:"a" (pte_val(BAD_PAGE)),
"D" ((long) empty_bad_page_table),
"c" (PAGE_SIZE/4)
:"di","cx");
return (pte_t *) empty_bad_page_table;
}
pte_t __bad_page(void)
{
extern char empty_bad_page[PAGE_SIZE];
__asm__ __volatile__("cld ; rep ; stosl":
:"a" (0),
"D" ((long) empty_bad_page),
"c" (PAGE_SIZE/4)
:"di","cx");
return pte_mkdirty(mk_pte((unsigned long) empty_bad_page, PAGE_SHARED));
}
void show_mem(void)
{
int i,free = 0,total = 0,reserved = 0;
int shared = 0;
printk("Mem-info:\n");
show_free_areas();
printk("Free swap: %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
i = high_memory >> PAGE_SHIFT;
while (i-- > 0) {
total++;
if (mem_map[i] & MAP_PAGE_RESERVED)
reserved++;
else if (!mem_map[i])
free++;
else
shared += mem_map[i]-1;
}
printk("%d pages of RAM\n",total);
printk("%d free pages\n",free);
printk("%d reserved pages\n",reserved);
printk("%d pages shared\n",shared);
show_buffers();
#ifdef CONFIG_NET
show_net_buffers();
#endif
}
extern unsigned long free_area_init(unsigned long, unsigned long);
/*
* paging_init() sets up the page tables - note that the first 4MB are
* already mapped by head.S.
*
* This routines also unmaps the page at virtual kernel address 0, so
* that we can trap those pesky NULL-reference errors in the kernel.
*/
unsigned long paging_init(unsigned long start_mem, unsigned long end_mem)
{
pgd_t * pg_dir;
pte_t * pg_table;
unsigned long tmp;
unsigned long address;
/*
* Physical page 0 is special; it's not touched by Linux since BIOS
* and SMM (for laptops with [34]86/SL chips) may need it. It is read
* and write protected to detect null pointer references in the
* kernel.
*/
#if 0
memset((void *) 0, 0, PAGE_SIZE);
#endif
start_mem = PAGE_ALIGN(start_mem);
address = 0;
pg_dir = swapper_pg_dir;
while (address < end_mem) {
/* map the memory at virtual addr 0xC0000000 */
pg_table = (pte_t *) (PAGE_MASK & pgd_val(pg_dir[768]));
if (!pg_table) {
pg_table = (pte_t *) start_mem;
start_mem += PAGE_SIZE;
}
/* also map it temporarily at 0x0000000 for init */
pgd_val(pg_dir[0]) = _PAGE_TABLE | (unsigned long) pg_table;
pgd_val(pg_dir[768]) = _PAGE_TABLE | (unsigned long) pg_table;
pg_dir++;
for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
if (address < end_mem)
*pg_table = mk_pte(address, PAGE_SHARED);
else
pte_clear(pg_table);
address += PAGE_SIZE;
}
}
invalidate();
return free_area_init(start_mem, end_mem);
}
void mem_init(unsigned long start_mem, unsigned long end_mem)
{
unsigned long start_low_mem = PAGE_SIZE;
int codepages = 0;
int reservedpages = 0;
int datapages = 0;
unsigned long tmp;
extern int etext;
end_mem &= PAGE_MASK;
high_memory = end_mem;
/* clear the zero-page */
memset(empty_zero_page, 0, PAGE_SIZE);
/* mark usable pages in the mem_map[] */
start_low_mem = PAGE_ALIGN(start_low_mem);
start_mem = PAGE_ALIGN(start_mem);
/*
* IBM messed up *AGAIN* in their thinkpad: 0xA0000 -> 0x9F000.
* They seem to have done something stupid with the floppy
* controller as well..
*/
while (start_low_mem < 0x9f000) {
mem_map[MAP_NR(start_low_mem)] = 0;
start_low_mem += PAGE_SIZE;
}
while (start_mem < high_memory) {
mem_map[MAP_NR(start_mem)] = 0;
start_mem += PAGE_SIZE;
}
#ifdef CONFIG_SCSI
scsi_mem_init(high_memory);
#endif
#ifdef CONFIG_SOUND
sound_mem_init();
#endif
for (tmp = 0 ; tmp < high_memory ; tmp += PAGE_SIZE) {
if (mem_map[MAP_NR(tmp)]) {
if (tmp >= 0xA0000 && tmp < 0x100000)
reservedpages++;
else if (tmp < (unsigned long) &etext)
codepages++;
else
datapages++;
continue;
}
mem_map[MAP_NR(tmp)] = 1;
free_page(tmp);
}
tmp = nr_free_pages << PAGE_SHIFT;
printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data)\n",
tmp >> 10,
high_memory >> 10,
codepages << (PAGE_SHIFT-10),
reservedpages << (PAGE_SHIFT-10),
datapages << (PAGE_SHIFT-10));
/* test if the WP bit is honoured in supervisor mode */
wp_works_ok = -1;
pg0[0] = pte_val(mk_pte(0, PAGE_READONLY));
invalidate();
__asm__ __volatile__("movb 0,%%al ; movb %%al,0": : :"ax", "memory");
pg0[0] = 0;
invalidate();
if (wp_works_ok < 0)
wp_works_ok = 0;
#ifdef CONFIG_TEST_VERIFY_AREA
wp_works_ok = 0;
#endif
return;
}
void si_meminfo(struct sysinfo *val)
{
int i;
i = high_memory >> PAGE_SHIFT;
val->totalram = 0;
val->sharedram = 0;
val->freeram = nr_free_pages << PAGE_SHIFT;
val->bufferram = buffermem;
while (i-- > 0) {
if (mem_map[i] & MAP_PAGE_RESERVED)
continue;
val->totalram++;
if (!mem_map[i])
continue;
val->sharedram += mem_map[i]-1;
}
val->totalram <<= PAGE_SHIFT;
val->sharedram <<= PAGE_SHIFT;
return;
}
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