/*
 *  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>
#include <linux/init.h>
#ifdef CONFIG_BLK_DEV_INITRD
#include <linux/blk.h>
#endif

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/dma.h>
#include <asm/fixmap.h>

extern void show_net_buffers(void);
extern unsigned long init_smp_mappings(unsigned long);

void __bad_pte_kernel(pmd_t *pmd)
{
	printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
	pmd_val(*pmd) = _KERNPG_TABLE + __pa(BAD_PAGETABLE);
}

void __bad_pte(pmd_t *pmd)
{
	printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
	pmd_val(*pmd) = _PAGE_TABLE + __pa(BAD_PAGETABLE);
}

pte_t *get_pte_kernel_slow(pmd_t *pmd, unsigned long offset)
{
	pte_t *pte;

	pte = (pte_t *) __get_free_page(GFP_KERNEL);
	if (pmd_none(*pmd)) {
		if (pte) {
			clear_page((unsigned long)pte);
			pmd_val(*pmd) = _KERNPG_TABLE + __pa(pte);
			return pte + offset;
		}
		pmd_val(*pmd) = _KERNPG_TABLE + __pa(BAD_PAGETABLE);
		return NULL;
	}
	free_page((unsigned long)pte);
	if (pmd_bad(*pmd)) {
		__bad_pte_kernel(pmd);
		return NULL;
	}
	return (pte_t *) pmd_page(*pmd) + offset;
}

pte_t *get_pte_slow(pmd_t *pmd, unsigned long offset)
{
	unsigned long pte;

	pte = (unsigned long) __get_free_page(GFP_KERNEL);
	if (pmd_none(*pmd)) {
		if (pte) {
			clear_page(pte);
			pmd_val(*pmd) = _PAGE_TABLE + __pa(pte);
			return (pte_t *)(pte + offset);
		}
		pmd_val(*pmd) = _PAGE_TABLE + __pa(BAD_PAGETABLE);
		return NULL;
	}
	free_page(pte);
	if (pmd_bad(*pmd)) {
		__bad_pte(pmd);
		return NULL;
	}
	return (pte_t *) (pmd_page(*pmd) + offset);
}


/*
 * 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 an 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, cached = 0;

	printk("Mem-info:\n");
	show_free_areas();
	printk("Free swap:       %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
	i = max_mapnr;
	while (i-- > 0) {
		total++;
		if (PageReserved(mem_map+i))
			reserved++;
		else if (PageSwapCache(mem_map+i))
			cached++;
		else if (!atomic_read(&mem_map[i].count))
			free++;
		else
			shared += atomic_read(&mem_map[i].count) - 1;
	}
	printk("%d pages of RAM\n",total);
	printk("%d reserved pages\n",reserved);
	printk("%d pages shared\n",shared);
	printk("%d pages swap cached\n",cached);
	printk("%ld pages in page table cache\n",pgtable_cache_size);
	show_buffers();
#ifdef CONFIG_NET
	show_net_buffers();
#endif
}

extern unsigned long free_area_init(unsigned long, unsigned long);

/* References to section boundaries */

extern char _text, _etext, _edata, __bss_start, _end;
extern char __init_begin, __init_end;

#define X86_CR4_VME		0x0001		/* enable vm86 extensions */
#define X86_CR4_PVI		0x0002		/* virtual interrupts flag enable */
#define X86_CR4_TSD		0x0004		/* disable time stamp at ipl 3 */
#define X86_CR4_DE		0x0008		/* enable debugging extensions */
#define X86_CR4_PSE		0x0010		/* enable page size extensions */
#define X86_CR4_PAE		0x0020		/* enable physical address extensions */
#define X86_CR4_MCE		0x0040		/* Machine check enable */
#define X86_CR4_PGE		0x0080		/* enable global pages */
#define X86_CR4_PCE		0x0100		/* enable performance counters at ipl 3 */

/*
 * Save the cr4 feature set we're using (ie
 * Pentium 4MB enable and PPro Global page
 * enable), so that any CPU's that boot up
 * after us can get the correct flags.
 */
unsigned long mmu_cr4_features __initdata = 0;

static inline void set_in_cr4(unsigned long mask)
{
	mmu_cr4_features |= mask;
	__asm__("movl %%cr4,%%eax\n\t"
		"orl %0,%%eax\n\t"
		"movl %%eax,%%cr4\n"
		: : "irg" (mask)
		:"ax");
}

/*
 * allocate page table(s) for compile-time fixed mappings
 */
static unsigned long fixmap_init (unsigned long start_mem)
{
	pgd_t * pg_dir;
	unsigned int idx;
	unsigned long address;

	start_mem &= PAGE_MASK;

	for (idx=1; idx < __end_of_fixed_addresses; idx += PTRS_PER_PTE)
	{
		address = fix_to_virt(__end_of_fixed_addresses-idx);
		pg_dir = swapper_pg_dir + (address >> PGDIR_SHIFT);
		memset((void *)start_mem, 0, PAGE_SIZE);
		pgd_val(*pg_dir) = _PAGE_TABLE | __pa(start_mem);
		start_mem += PAGE_SIZE;
	}

	return start_mem;
}

static void set_pte_phys (unsigned long vaddr, unsigned long phys)
{
	pgprot_t prot;
	pte_t * pte;

	pte = pte_offset(pmd_offset(pgd_offset_k(vaddr), vaddr), vaddr);
	prot = PAGE_KERNEL;
	if (boot_cpu_data.x86_capability & X86_FEATURE_PGE)
		pgprot_val(prot) |= _PAGE_GLOBAL;
	set_pte(pte, mk_pte_phys(phys, prot));

	local_flush_tlb();
}

void set_fixmap (enum fixed_addresses idx, unsigned long phys)
{
	unsigned long address = fix_to_virt(idx);

	set_pte_phys (address,phys);
}

/*
 * 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.
 */
__initfunc(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.
 */
#ifdef __SMP__
	/*
	 * FIXME: Linux assumes you have 640K of base ram..
	 * this continues the error...
	 *
	 * 1) Scan the bottom 1K for a signature
	 * 2) Scan the top 1K of base RAM
	 * 3) Scan the 64K of bios
	 */
	if (!smp_scan_config(0x0,0x400) &&
	    !smp_scan_config(639*0x400,0x400) &&
	    !smp_scan_config(0xF0000,0x10000)) {
		/*
		 * 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);
	}
#endif
	start_mem = PAGE_ALIGN(start_mem);
	address = PAGE_OFFSET;
	pg_dir = swapper_pg_dir;
	/* unmap the original low memory mappings */
	pgd_val(pg_dir[0]) = 0;

	/* Map whole memory from PAGE_OFFSET */
	pg_dir += USER_PGD_PTRS;
	while (address < end_mem) {
		/*
		 * If we're running on a Pentium CPU, we can use the 4MB
		 * page tables. 
		 *
		 * The page tables we create span up to the next 4MB
		 * virtual memory boundary, but that's OK as we won't
		 * use that memory anyway.
		 */
		if (boot_cpu_data.x86_capability & X86_FEATURE_PSE) {
			unsigned long __pe;

			set_in_cr4(X86_CR4_PSE);
			boot_cpu_data.wp_works_ok = 1;
			__pe = _KERNPG_TABLE + _PAGE_4M + __pa(address);
			/* Make it "global" too if supported */
			if (boot_cpu_data.x86_capability & X86_FEATURE_PGE) {
				set_in_cr4(X86_CR4_PGE);
				__pe += _PAGE_GLOBAL;
			}
			pgd_val(*pg_dir) = __pe;
			pg_dir++;
			address += 4*1024*1024;
			continue;
		}

		/*
		 * We're on a [34]86, use normal page tables.
		 * pg_table is physical at this point
		 */
		pg_table = (pte_t *) (PAGE_MASK & pgd_val(*pg_dir));
		if (!pg_table) {
			pg_table = (pte_t *) __pa(start_mem);
			start_mem += PAGE_SIZE;
		}

		pgd_val(*pg_dir) = _PAGE_TABLE | (unsigned long) pg_table;
		pg_dir++;

		/* now change pg_table to kernel virtual addresses */
		pg_table = (pte_t *) __va(pg_table);
		for (tmp = 0 ; tmp < PTRS_PER_PTE ; tmp++,pg_table++) {
			pte_t pte = mk_pte(address, PAGE_KERNEL);
			if (address >= end_mem)
				pte_val(pte) = 0;
			set_pte(pg_table, pte);
			address += PAGE_SIZE;
		}
	}
	start_mem = fixmap_init(start_mem);
#ifdef __SMP__
	start_mem = init_smp_mappings(start_mem);
#endif
	local_flush_tlb();

	return free_area_init(start_mem, end_mem);
}

/*
 * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 * and also on some strange 486's (NexGen etc.). All 586+'s are OK. The jumps
 * before and after the test are here to work-around some nasty CPU bugs.
 */

__initfunc(void test_wp_bit(void))
{
	unsigned char tmp_reg;
	unsigned long old = pg0[0];

	printk("Checking if this processor honours the WP bit even in supervisor mode... ");
	pg0[0] = pte_val(mk_pte(PAGE_OFFSET, PAGE_READONLY));
	local_flush_tlb();
	current->mm->mmap->vm_start += PAGE_SIZE;
	__asm__ __volatile__(
		"jmp 1f; 1:\n"
		"movb %0,%1\n"
		"movb %1,%0\n"
		"jmp 1f; 1:\n"
		:"=m" (*(char *) __va(0)),
		 "=q" (tmp_reg)
		:/* no inputs */
		:"memory");
	pg0[0] = old;
	local_flush_tlb();
	current->mm->mmap->vm_start -= PAGE_SIZE;
	if (boot_cpu_data.wp_works_ok < 0) {
		boot_cpu_data.wp_works_ok = 0;
		printk("No.\n");
#ifndef CONFIG_M386
		panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
#endif
	} else
		printk(".\n");
}

__initfunc(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;
	int initpages = 0;
	unsigned long tmp;

	end_mem &= PAGE_MASK;
	high_memory = (void *) end_mem;
	max_mapnr = num_physpages = MAP_NR(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)+PAGE_OFFSET;

#ifdef __SMP__
	/*
	 * But first pinch a few for the stack/trampoline stuff
	 *	FIXME: Don't need the extra page at 4K, but need to fix
	 *	trampoline before removing it. (see the GDT 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+PAGE_OFFSET) {
		clear_bit(PG_reserved, &mem_map[MAP_NR(start_low_mem)].flags);
		start_low_mem += PAGE_SIZE;
	}

	while (start_mem < end_mem) {
		clear_bit(PG_reserved, &mem_map[MAP_NR(start_mem)].flags);
		start_mem += PAGE_SIZE;
	}
	for (tmp = PAGE_OFFSET ; tmp < end_mem ; 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 >= (unsigned long) &_text && tmp < (unsigned long) &_edata) {
				if (tmp < (unsigned long) &_etext)
					codepages++;
				else
					datapages++;
			} else if (tmp >= (unsigned long) &__init_begin
				   && tmp < (unsigned long) &__init_end)
				initpages++;
			else if (tmp >= (unsigned long) &__bss_start
				 && tmp < (unsigned long) start_mem)
				datapages++;
			else
				reservedpages++;
			continue;
		}
		atomic_set(&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);
	}
	printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init)\n",
		(unsigned long) nr_free_pages << (PAGE_SHIFT-10),
		max_mapnr << (PAGE_SHIFT-10),
		codepages << (PAGE_SHIFT-10),
		reservedpages << (PAGE_SHIFT-10),
		datapages << (PAGE_SHIFT-10),
		initpages << (PAGE_SHIFT-10));

	if (boot_cpu_data.wp_works_ok < 0)
		test_wp_bit();
}

void free_initmem(void)
{
	unsigned long addr;
	
	addr = (unsigned long)(&__init_begin);
	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
		mem_map[MAP_NR(addr)].flags &= ~(1 << PG_reserved);
		atomic_set(&mem_map[MAP_NR(addr)].count, 1);
		free_page(addr);
	}
	printk ("Freeing unused kernel memory: %dk freed\n", (&__init_end - &__init_begin) >> 10);
}

void si_meminfo(struct sysinfo *val)
{
	int i;

	i = max_mapnr;
	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 (!atomic_read(&mem_map[i].count))
			continue;
		val->sharedram += atomic_read(&mem_map[i].count) - 1;
	}
	val->totalram <<= PAGE_SHIFT;
	val->sharedram <<= PAGE_SHIFT;
	return;
}
