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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 <linux/swap.h>

#include <linux/smp.h>

#ifdef CONFIG_BLK_DEV_INITRD

#include <linux/blk.h>

#endif

#include <asm/system.h>

#include <asm/segment.h>

#include <asm/pgtable.h>

#include <asm/dma.h>

#if 0

/*

 * The SMP kernel can't handle the 4MB page table optimizations yet

 */

#ifdef __SMP__

#undef USE_PENTIUM_MM

#endif

#endif

const char bad_pmd_string[] = "Bad pmd in pte_alloc: %08lx\n";

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 (PageReserved(mem_map+i))

                        reserved++;

                else if (!mem_map[i].count)

                        free++;

                else

                        shared += mem_map[i].count-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.

 * It may also hold the MP configuration table when we are booting SMP.

 */

#if 0

        memset((void *) 0, 0, PAGE_SIZE);

#endif

#ifdef __SMP__

        if (!smp_scan_config(0x0,0x400))        /* Scan the bottom 1K for a signature */

        {

                /*

                 *      FIXME: Linux assumes you have 640K of base ram.. this continues

                 *      the error...

                 */

                if (!smp_scan_config(639*0x400,0x400))  /* Scan the top 1K of base RAM */

                {

                        if(!smp_scan_config(0xF0000,0x10000)) /* Scan the 64K of bios */

                        {

                                /*

                                 * If it is an SMP machine we should know now, unless the

                                 * configuration is in an EISA/MCA bus machine with an

                                 * extended bios data area.

                                 *

                                 * there is a real-mode segmented pointer pointing to the

                                 * 4K EBDA area at 0x40E, calculate and scan it here:

                                 */

                                address = *(unsigned short *)phys_to_virt(0x40E);

                                address<<=4;

                                smp_scan_config(address, 0x1000);

                        }

                }

        }

        /*

         *      If it is an SMP machine we should know now, unless the configuration

         *      is in an EISA/MCA bus machine with an extended bios data area. I don't

         *      have such a machine so someone else can fill in the check of the EBDA

         *      here.

         */

/*      smp_alloc_memory(8192); */

#endif

#ifdef TEST_VERIFY_AREA

        wp_works_ok = 0;

#endif

        start_mem = PAGE_ALIGN(start_mem);

        address = 0;

        pg_dir = swapper_pg_dir;

        while (address < end_mem) {

#ifdef USE_PENTIUM_MM

                /*

                 * This will create page tables that

                 * span up to the next 4MB virtual

                 * memory boundary, but that's ok,

                 * we won't use that memory anyway.

                 */

                if (x86_capability & 8) {

#ifdef GAS_KNOWS_CR4

                        __asm__("movl %%cr4,%%eax\n\t"

                                "orl $16,%%eax\n\t"

                                "movl %%eax,%%cr4"

                                : : :"ax");

#else

                        __asm__(".byte 0x0f,0x20,0xe0\n\t"

                                "orl $16,%%eax\n\t"

                                ".byte 0x0f,0x22,0xe0"

                                : : :"ax");

#endif

                        wp_works_ok = 1;

                        pgd_val(pg_dir[0]) = _PAGE_TABLE | _PAGE_4M | address;

                        pgd_val(pg_dir[USER_PGD_PTRS]) = _PAGE_TABLE | _PAGE_4M | address;

                        pg_dir++;

                        address += 4*1024*1024;

                        continue;

                }

#endif

                /* map the memory at virtual addr PAGE_OFFSET */

                pg_table = (pte_t *) (PAGE_MASK & pgd_val(pg_dir[USER_PGD_PTRS]));

                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[USER_PGD_PTRS]) = _PAGE_TABLE | (unsigned long) pg_table;

                pg_dir++;

                for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {

                        if (address < end_mem)

                                set_pte(pg_table, mk_pte(address, PAGE_SHARED));

                        else

                                pte_clear(pg_table);

                        address += PAGE_SIZE;

                }

        }

        local_flush_tlb();

        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);

#ifdef __SMP__

        /*

         * But first pinch a few for the stack/trampoline stuff

         */

        start_low_mem += PAGE_SIZE;                             /* 32bit startup code */

        start_low_mem = smp_alloc_memory(start_low_mem);        /* AP processor stacks */

#endif

        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) {

                clear_bit(PG_reserved, &mem_map[MAP_NR(start_low_mem)].flags);

                start_low_mem += PAGE_SIZE;

        }

        while (start_mem < high_memory) {

                clear_bit(PG_reserved, &mem_map[MAP_NR(start_mem)].flags);

                start_mem += PAGE_SIZE;

        }

        for (tmp = 0 ; tmp < high_memory ; tmp += PAGE_SIZE) {

                if (tmp >= MAX_DMA_ADDRESS)

                        clear_bit(PG_DMA, &mem_map[MAP_NR(tmp)].flags);

                if (PageReserved(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)].count = 1;

#ifdef CONFIG_BLK_DEV_INITRD

                if (!initrd_start || (tmp < initrd_start || tmp >=

                    initrd_end))

#endif

                        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 */

        if (wp_works_ok < 0) {

                pg0[0] = pte_val(mk_pte(0, PAGE_READONLY));

                local_flush_tlb();

                __asm__ __volatile__("movb 0,%%al ; movb %%al,0": : :"ax", "memory");

                pg0[0] = 0;

                local_flush_tlb();

                if (wp_works_ok < 0)

                        wp_works_ok = 0;

        }

        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 (PageReserved(mem_map+i))

                        continue;

                val->totalram++;

                if (!mem_map[i].count)

                        continue;

                val->sharedram += mem_map[i].count-1;

        }

        val->totalram <<= PAGE_SHIFT;

        val->sharedram <<= PAGE_SHIFT;

        return;

}