root/arch/x86/mm/pgtable_32.c

DEFINITIONS

1. set_pte_vaddr
2. set_pmd_pfn
3. reserve_top_address
4. parse_vmalloc
5. parse_reservetop

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/nmi.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/quicklist.h>

#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

/*
 * Associate a virtual page frame with a given physical page frame 
 * and protection flags for that frame.
 */ 
void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pgd = swapper_pg_dir + pgd_index(vaddr);
        if (pgd_none(*pgd)) {
                BUG();
                return;
        }
        pud = pud_offset(pgd, vaddr);
        if (pud_none(*pud)) {
                BUG();
                return;
        }
        pmd = pmd_offset(pud, vaddr);
        if (pmd_none(*pmd)) {
                BUG();
                return;
        }
        pte = pte_offset_kernel(pmd, vaddr);
        if (pte_val(pteval))
                set_pte_present(&init_mm, vaddr, pte, pteval);
        else
                pte_clear(&init_mm, vaddr, pte);

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

/*
 * Associate a large virtual page frame with a given physical page frame 
 * and protection flags for that frame. pfn is for the base of the page,
 * vaddr is what the page gets mapped to - both must be properly aligned. 
 * The pmd must already be instantiated. Assumes PAE mode.
 */ 
void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;

        if (vaddr & (PMD_SIZE-1)) {             /* vaddr is misaligned */
                printk(KERN_WARNING "set_pmd_pfn: vaddr misaligned\n");
                return; /* BUG(); */
        }
        if (pfn & (PTRS_PER_PTE-1)) {           /* pfn is misaligned */
                printk(KERN_WARNING "set_pmd_pfn: pfn misaligned\n");
                return; /* BUG(); */
        }
        pgd = swapper_pg_dir + pgd_index(vaddr);
        if (pgd_none(*pgd)) {
                printk(KERN_WARNING "set_pmd_pfn: pgd_none\n");
                return; /* BUG(); */
        }
        pud = pud_offset(pgd, vaddr);
        pmd = pmd_offset(pud, vaddr);
        set_pmd(pmd, pfn_pmd(pfn, flags));
        /*
         * It's enough to flush this one mapping.
         * (PGE mappings get flushed as well)
         */
        __flush_tlb_one(vaddr);
}

unsigned long __FIXADDR_TOP = 0xfffff000;
EXPORT_SYMBOL(__FIXADDR_TOP);

/**
 * reserve_top_address - reserves a hole in the top of kernel address space
 * @reserve - size of hole to reserve
 *
 * Can be used to relocate the fixmap area and poke a hole in the top
 * of kernel address space to make room for a hypervisor.
 */
void __init reserve_top_address(unsigned long reserve)
{
        BUG_ON(fixmaps_set > 0);
        printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
               (int)-reserve);
        __FIXADDR_TOP = -reserve - PAGE_SIZE;
        __VMALLOC_RESERVE += reserve;
}

/*
 * vmalloc=size forces the vmalloc area to be exactly 'size'
 * bytes. This can be used to increase (or decrease) the
 * vmalloc area - the default is 128m.
 */
static int __init parse_vmalloc(char *arg)
{
        if (!arg)
                return -EINVAL;

        /* Add VMALLOC_OFFSET to the parsed value due to vm area guard hole*/
        __VMALLOC_RESERVE = memparse(arg, &arg) + VMALLOC_OFFSET;
        return 0;
}
early_param("vmalloc", parse_vmalloc);

/*
 * reservetop=size reserves a hole at the top of the kernel address space which
 * a hypervisor can load into later.  Needed for dynamically loaded hypervisors,
 * so relocating the fixmap can be done before paging initialization.
 */
static int __init parse_reservetop(char *arg)
{
        unsigned long address;

        if (!arg)
                return -EINVAL;

        address = memparse(arg, &arg);
        reserve_top_address(address);
        return 0;
}
early_param("reservetop", parse_reservetop);