init_32.c

linux 内核源代码

/*
 *  linux/arch/i386/mm/init.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 */

#include <linux/module.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/hugetlb.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/pfn.h>
#include <linux/poison.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/efi.h>
#include <linux/memory_hotplug.h>
#include <linux/initrd.h>
#include <linux/cpumask.h>

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/apic.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/paravirt.h>

unsigned int __VMALLOC_RESERVE = 128 << 20;

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
unsigned long highstart_pfn, highend_pfn;

static int noinline do_test_wp_bit(void);

/*
 * Creates a middle page table and puts a pointer to it in the
 * given global directory entry. This only returns the gd entry
 * in non-PAE compilation mode, since the middle layer is folded.
 */
static pmd_t * __init one_md_table_init(pgd_t *pgd)
{
	pud_t *pud;
	pmd_t *pmd_table;
		
#ifdef CONFIG_X86_PAE
	if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
		pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);

		paravirt_alloc_pd(__pa(pmd_table) >> PAGE_SHIFT);
		set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
		pud = pud_offset(pgd, 0);
		if (pmd_table != pmd_offset(pud, 0))
			BUG();
	}
#endif
	pud = pud_offset(pgd, 0);
	pmd_table = pmd_offset(pud, 0);
	return pmd_table;
}

/*
 * Create a page table and place a pointer to it in a middle page
 * directory entry.
 */
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
	if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
		pte_t *page_table = NULL;

#ifdef CONFIG_DEBUG_PAGEALLOC
		page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
#endif
		if (!page_table)
			page_table =
				(pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);

		paravirt_alloc_pt(&init_mm, __pa(page_table) >> PAGE_SHIFT);
		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
	}

	return pte_offset_kernel(pmd, 0);
}

/*
 * This function initializes a certain range of kernel virtual memory 
 * with new bootmem page tables, everywhere page tables are missing in
 * the given range.
 */

/*
 * NOTE: The pagetables are allocated contiguous on the physical space 
 * so we can cache the place of the first one and move around without 
 * checking the pgd every time.
 */
static void __init page_table_range_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
{
	pgd_t *pgd;
	pmd_t *pmd;
	int pgd_idx, pmd_idx;
	unsigned long vaddr;

	vaddr = start;
	pgd_idx = pgd_index(vaddr);
	pmd_idx = pmd_index(vaddr);
	pgd = pgd_base + pgd_idx;

	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
		pmd = one_md_table_init(pgd);
		pmd = pmd + pmd_index(vaddr);
		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_idx++) {
			one_page_table_init(pmd);

			vaddr += PMD_SIZE;
		}
		pmd_idx = 0;
	}
}

static inline int is_kernel_text(unsigned long addr)
{
	if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
		return 1;
	return 0;
}

/*
 * This maps the physical memory to kernel virtual address space, a total 
 * of max_low_pfn pages, by creating page tables starting from address 
 * PAGE_OFFSET.
 */
static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
{
	unsigned long pfn;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int pgd_idx, pmd_idx, pte_ofs;

	pgd_idx = pgd_index(PAGE_OFFSET);
	pgd = pgd_base + pgd_idx;
	pfn = 0;

	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
		pmd = one_md_table_init(pgd);
		if (pfn >= max_low_pfn)
			continue;
		for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD && pfn < max_low_pfn; pmd++, pmd_idx++) {
			unsigned int address = pfn * PAGE_SIZE + PAGE_OFFSET;

			/* Map with big pages if possible, otherwise create normal page tables. */
			if (cpu_has_pse) {
				unsigned int address2 = (pfn + PTRS_PER_PTE - 1) * PAGE_SIZE + PAGE_OFFSET + PAGE_SIZE-1;
				if (is_kernel_text(address) || is_kernel_text(address2))
					set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
				else
					set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE));

				pfn += PTRS_PER_PTE;
			} else {
				pte = one_page_table_init(pmd);

				for (pte_ofs = 0;
				     pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn;
				     pte++, pfn++, pte_ofs++, address += PAGE_SIZE) {
					if (is_kernel_text(address))
						set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
					else
						set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
				}
			}
		}
	}
}

static inline int page_kills_ppro(unsigned long pagenr)
{
	if (pagenr >= 0x70000 && pagenr <= 0x7003F)
		return 1;
	return 0;
}

int page_is_ram(unsigned long pagenr)
{
	int i;
	unsigned long addr, end;

	if (efi_enabled) {
		efi_memory_desc_t *md;
		void *p;

		for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
			md = p;
			if (!is_available_memory(md))
				continue;
			addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
			end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;

			if ((pagenr >= addr) && (pagenr < end))
				return 1;
		}
		return 0;
	}

	for (i = 0; i < e820.nr_map; i++) {

		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;
}

#ifdef CONFIG_HIGHMEM
pte_t *kmap_pte;
pgprot_t kmap_prot;

#define kmap_get_fixmap_pte(vaddr)					\
	pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), vaddr), (vaddr)), (vaddr))

static void __init kmap_init(void)
{
	unsigned long kmap_vstart;

	/* cache the first kmap pte */
	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);

	kmap_prot = PAGE_KERNEL;
}

static void __init permanent_kmaps_init(pgd_t *pgd_base)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	unsigned long vaddr;

	vaddr = PKMAP_BASE;
	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);

	pgd = swapper_pg_dir + pgd_index(vaddr);
	pud = pud_offset(pgd, vaddr);
	pmd = pmd_offset(pud, vaddr);
	pte = pte_offset_kernel(pmd, vaddr);
	pkmap_page_table = pte;	
}

static void __meminit free_new_highpage(struct page *page)
{
	init_page_count(page);
	__free_page(page);
	totalhigh_pages++;
}

void __init add_one_highpage_init(struct page *page, int pfn, int bad_ppro)
{
	if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
		ClearPageReserved(page);
		free_new_highpage(page);
	} else
		SetPageReserved(page);
}

static int __meminit add_one_highpage_hotplug(struct page *page, unsigned long pfn)
{
	free_new_highpage(page);
	totalram_pages++;
#ifdef CONFIG_FLATMEM
	max_mapnr = max(pfn, max_mapnr);
#endif
	num_physpages++;
	return 0;
}

/*
 * Not currently handling the NUMA case.
 * Assuming single node and all memory that
 * has been added dynamically that would be
 * onlined here is in HIGHMEM
 */
void __meminit online_page(struct page *page)
{
	ClearPageReserved(page);
	add_one_highpage_hotplug(page, page_to_pfn(page));
}


#ifdef CONFIG_NUMA
extern void set_highmem_pages_init(int);
#else
static void __init set_highmem_pages_init(int bad_ppro)
{
	int pfn;
	for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) {
		/*
		 * Holes under sparsemem might not have no mem_map[]:
		 */
		if (pfn_valid(pfn))
			add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
	}
	totalram_pages += totalhigh_pages;
}
#endif /* CONFIG_FLATMEM */

#else
#define kmap_init() do { } while (0)
#define permanent_kmaps_init(pgd_base) do { } while (0)
#define set_highmem_pages_init(bad_ppro) do { } while (0)
#endif /* CONFIG_HIGHMEM */

unsigned long long __PAGE_KERNEL = _PAGE_KERNEL;
EXPORT_SYMBOL(__PAGE_KERNEL);
unsigned long long __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;

#ifdef CONFIG_NUMA
extern void __init remap_numa_kva(void);
#else
#define remap_numa_kva() do {} while (0)
#endif

void __init native_pagetable_setup_start(pgd_t *base)
{
#ifdef CONFIG_X86_PAE
	int i;

	/*
	 * Init entries of the first-level page table to the
	 * zero page, if they haven't already been set up.
	 *
	 * In a normal native boot, we'll be running on a
	 * pagetable rooted in swapper_pg_dir, but not in PAE
	 * mode, so this will end up clobbering the mappings
	 * for the lower 24Mbytes of the address space,
	 * without affecting the kernel address space.
	 */
	for (i = 0; i < USER_PTRS_PER_PGD; i++)
		set_pgd(&base[i],
			__pgd(__pa(empty_zero_page) | _PAGE_PRESENT));

	/* Make sure kernel address space is empty so that a pagetable
	   will be allocated for it. */
	memset(&base[USER_PTRS_PER_PGD], 0,
	       KERNEL_PGD_PTRS * sizeof(pgd_t));
#else
	paravirt_alloc_pd(__pa(swapper_pg_dir) >> PAGE_SHIFT);
#endif
}

void __init native_pagetable_setup_done(pgd_t *base)
{
#ifdef CONFIG_X86_PAE
	/*
	 * Add low memory identity-mappings - SMP needs it when
	 * starting up on an AP from real-mode. In the non-PAE
	 * case we already have these mappings through head.S.
	 * All user-space mappings are explicitly cleared after
	 * SMP startup.
	 */
	set_pgd(&base[0], base[USER_PTRS_PER_PGD]);
#endif
}

/*
 * Build a proper pagetable for the kernel mappings.  Up until this
 * point, we've been running on some set of pagetables constructed by
 * the boot process.
 *
 * If we're booting on native hardware, this will be a pagetable
 * constructed in arch/i386/kernel/head.S, and not running in PAE mode
 * (even if we'll end up running in PAE).  The root of the pagetable
 * will be swapper_pg_dir.
 *
 * If we're booting paravirtualized under a hypervisor, then there are
 * more options: we may already be running PAE, and the pagetable may
 * or may not be based in swapper_pg_dir.  In any case,
 * paravirt_pagetable_setup_start() will set up swapper_pg_dir
 * appropriately for the rest of the initialization to work.
 *
 * In general, pagetable_init() assumes that the pagetable may already
 * be partially populated, and so it avoids stomping on any existing
 * mappings.
 */
static void __init pagetable_init (void)
{
	unsigned long vaddr, end;
	pgd_t *pgd_base = swapper_pg_dir;

	paravirt_pagetable_setup_start(pgd_base);

	/* Enable PSE if available */
	if (cpu_has_pse)
		set_in_cr4(X86_CR4_PSE);

	/* Enable PGE if available */
	if (cpu_has_pge) {
		set_in_cr4(X86_CR4_PGE);
		__PAGE_KERNEL |= _PAGE_GLOBAL;