init.c

是关于linux2.5.1的完全源码

/*
 *  linux/arch/x86_64/mm/init.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Copyright (C) 2000  Pavel Machek <[e-mail]>
 *  Copyright (C) 2002  Andi Kleen <[e-mail]>
 */

#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.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 <linux/pagemap.h>
#include <linux/bootmem.h>

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/apic.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>

mmu_gather_t mmu_gathers[NR_CPUS];

static unsigned long totalram_pages;

/*
 * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
 * physical space so we can cache the place of the first one and move
 * around without checking the pgd every time.
 */

void show_mem(void)
{
	int i, 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 (page_count(mem_map+i))
			shared += page_count(mem_map+i) - 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);
	show_buffers();
}

/* References to section boundaries */

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

int after_bootmem;

static void *spp_getpage(void)
{ 
	void *ptr;
	if (after_bootmem)
		ptr = (void *) get_free_page(GFP_ATOMIC); 
	else
		ptr = alloc_bootmem_low(PAGE_SIZE); 
	if (!ptr)
		panic("set_pte_phys: cannot allocate page data %s\n", after_bootmem?"after bootmem":"");
	return ptr;
} 

static void set_pte_phys(unsigned long vaddr,
			 unsigned long phys, pgprot_t prot)
{
	pml4_t *level4;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;

	level4 = pml4_offset_k(vaddr);
	if (pml4_none(*level4)) {
		printk("PML4 FIXMAP MISSING, it should be setup in head.S!\n");
		return;
	}
	pgd = level3_offset_k(level4, vaddr);
	if (pgd_none(*pgd)) {
		pmd = (pmd_t *) spp_getpage(); 
		set_pgd(pgd, __pgd(__pa(pmd) | _KERNPG_TABLE | _PAGE_USER));
		if (pmd != pmd_offset(pgd, 0)) {
			printk("PAGETABLE BUG #01!\n");
			return;
		}
	}
	pmd = pmd_offset(pgd, vaddr);
	if (pmd_none(*pmd)) {
		pte = (pte_t *) spp_getpage();
		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE | _PAGE_USER));
		if (pte != pte_offset_kernel(pmd, 0)) {
			printk("PAGETABLE BUG #02!\n");
			return;
		}
	}
	pte = pte_offset_kernel(pmd, vaddr);
	if (pte_val(*pte))
		pte_ERROR(*pte);
	set_pte(pte, mk_pte_phys(phys, prot));

	/*
	 * It's enough to flush this one mapping.
	 * (PGE mappings get flushed as well)
	 */
	__flush_tlb_one(vaddr);
}

/* NOTE: this is meant to be run only at boot */
void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t prot)
{
	unsigned long address = __fix_to_virt(idx);

	if (idx >= __end_of_fixed_addresses) {
		printk("Invalid __set_fixmap\n");
		return;
	}
	set_pte_phys(address, phys, prot);
}

extern unsigned long start_pfn, end_pfn; 
extern pmd_t temp_boot_pmds[]; 

static  struct temp_map { 
	pmd_t *pmd;
	void  *address; 
	int    allocated; 
} temp_mappings[] __initdata = { 
	{ &temp_boot_pmds[0], (void *)(40UL * 1024 * 1024) },
	{ &temp_boot_pmds[1], (void *)(42UL * 1024 * 1024) }, 
	{}
}; 

static __init void *alloc_low_page(int *index, unsigned long *phys) 
{ 
	struct temp_map *ti;
	int i; 
	unsigned long pfn = start_pfn++, paddr; 
	void *adr;

	if (pfn >= end_pfn) 
		panic("alloc_low_page: ran out of memory"); 
	for (i = 0; temp_mappings[i].allocated; i++) {
		if (!temp_mappings[i].pmd) 
			panic("alloc_low_page: ran out of temp mappings"); 
	} 
	ti = &temp_mappings[i];
	paddr = (pfn & (~511)) << PAGE_SHIFT; 
	set_pmd(ti->pmd, __pmd(paddr | _KERNPG_TABLE | _PAGE_PSE)); 
	ti->allocated = 1; 
	__flush_tlb(); 	       
	adr = ti->address + (pfn & 511)*PAGE_SIZE; 
	*index = i; 
	*phys  = pfn * PAGE_SIZE;  
	return adr; 
} 

static __init void unmap_low_page(int i)
{ 
	struct temp_map *ti = &temp_mappings[i];
	set_pmd(ti->pmd, __pmd(0));
	ti->allocated = 0; 
} 

static void __init phys_pgd_init(pgd_t *pgd, unsigned long address, unsigned long end)
{ 
	long i, j; 

	i = pgd_index(address);
	pgd = pgd + i;
	for (; i < PTRS_PER_PGD; pgd++, i++) {
		int map; 
		unsigned long paddr = i*PGDIR_SIZE, pmd_phys;
		pmd_t *pmd;

		if (paddr >= end) { 
			for (; i < PTRS_PER_PGD; i++, pgd++) 
				set_pgd(pgd, __pgd(0)); 
			break;
		} 
		pmd = alloc_low_page(&map, &pmd_phys);
		set_pgd(pgd, __pgd(pmd_phys | _KERNPG_TABLE));
		for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
			unsigned long pe;

			paddr = i*PGDIR_SIZE + j*PMD_SIZE;
			if (paddr >= end) { 
				for (; j < PTRS_PER_PMD; j++, pmd++)
					set_pmd(pmd,  __pmd(0)); 
				break;
		}
			pe = _PAGE_PSE | _KERNPG_TABLE | _PAGE_GLOBAL | paddr;
			set_pmd(pmd, __pmd(pe));
		}
		unmap_low_page(map);
	}
	__flush_tlb();
} 

/* Setup the direct mapping of the physical memory at PAGE_OFFSET.
   This runs before bootmem is initialized and gets pages directly from the 
   physical memory. To access them they are temporarily mapped. */
void __init init_memory_mapping(void) 
{ 
	unsigned long adr;	       
	unsigned long end;
	unsigned long next; 

	end = PAGE_OFFSET + (end_pfn * PAGE_SIZE); 
	for (adr = PAGE_OFFSET; adr < end; adr = next) { 
		int map;
		unsigned long pgd_phys; 
		pgd_t *pgd = alloc_low_page(&map, &pgd_phys);
		next = adr + (512UL * 1024 * 1024 * 1024);
		if (next > end) 
			next = end; 
		phys_pgd_init(pgd, adr-PAGE_OFFSET, next-PAGE_OFFSET); 
		set_pml4(init_level4_pgt + pml4_index(adr), mk_kernel_pml4(pgd_phys));
		unmap_low_page(map);   
	} 
	asm volatile("movq %%cr4,%0" : "=r" (mmu_cr4_features));
	__flush_tlb_all();
}

extern struct x8664_pda cpu_pda[NR_CPUS];

void __init zap_low_mappings (void)
{
	int i;
	for (i = 0; i < NR_CPUS; i++) {
		if (cpu_pda[i].level4_pgt) 
			cpu_pda[i].level4_pgt[0] = 0; 
	}
	flush_tlb_all();
}

void __init paging_init(void)
{
	{
		unsigned long zones_size[MAX_NR_ZONES] = {0, 0, 0};
		unsigned int max_dma, low;

		max_dma = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
		low = max_low_pfn;

		if (low < max_dma)
			zones_size[ZONE_DMA] = low;
		else {
			zones_size[ZONE_DMA] = max_dma;
			zones_size[ZONE_NORMAL] = low - max_dma;
		}
		free_area_init(zones_size);
	}
	return;
}


static inline int page_is_ram (unsigned long pagenr)
{
	int i;

	for (i = 0; i < e820.nr_map; i++) {
		unsigned long addr, end;

		if (e820.map[i].type != E820_RAM)	/* not usable memory */
			continue;
		/*
		 *	!!!FIXME!!! Some BIOSen report areas as RAM that
		 *	are not. Notably the 640->1Mb area. We need a sanity
		 *	check here.
		 */
		addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
		end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
		if  ((pagenr >= addr) && (pagenr < end))
			return 1;
	}
	return 0;
}

void __init mem_init(void)
{
	int codesize, reservedpages, datasize, initsize;
	int tmp;

	if (!mem_map)
		BUG();

	max_mapnr = num_physpages = max_low_pfn;
	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);

	/* clear the zero-page */
	memset(empty_zero_page, 0, PAGE_SIZE);

	/* this will put all low memory onto the freelists */
	totalram_pages += free_all_bootmem();

	after_bootmem = 1;

	reservedpages = 0;
	for (tmp = 0; tmp < max_low_pfn; tmp++)
		/*
		 * Only count reserved RAM pages
		 */
		if (page_is_ram(tmp) && PageReserved(mem_map+tmp))
			reservedpages++;
	codesize =  (unsigned long) &_etext - (unsigned long) &_text;
	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;

	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),
		codesize >> 10,
		reservedpages << (PAGE_SHIFT-10),
		datasize >> 10,
		initsize >> 10);

	/*
	 * Subtle. SMP is doing its boot stuff late (because it has to
	 * fork idle threads) - but it also needs low mappings for the
	 * protected-mode entry to work. We zap these entries only after
	 * the WP-bit has been tested.
	 */
#ifndef CONFIG_SMP
	zap_low_mappings();
#endif
}

void free_initmem(void)
{
	unsigned long addr;

	addr = (unsigned long)(&__init_begin);
	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
		ClearPageReserved(virt_to_page(addr));
		set_page_count(virt_to_page(addr), 1);
#ifdef CONFIG_INIT_DEBUG
		memset(addr & ~(PAGE_SIZE-1), 0xcc, PAGE_SIZE); 
#endif
		free_page(addr);
		totalram_pages++;
	}
	printk ("Freeing unused kernel memory: %luk freed\n", (&__init_end - &__init_begin) >> 10);
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
	if (start < (unsigned long)&_end)
		return;
	printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
	for (; start < end; start += PAGE_SIZE) {
		ClearPageReserved(virt_to_page(start));
		set_page_count(virt_to_page(start), 1);
		free_page(start);
		totalram_pages++;
	}
}
#endif

void si_meminfo(struct sysinfo *val)
{
	val->totalram = totalram_pages;
	val->sharedram = 0;
	val->freeram = nr_free_pages();
	val->bufferram = atomic_read(&buffermem_pages);
	val->totalhigh = 0;
	val->freehigh = nr_free_highpages();
	val->mem_unit = PAGE_SIZE;
	return;
}