254 строки
6.4 KiB
C
254 строки
6.4 KiB
C
/*
|
|
* linux/mm/fremap.c
|
|
*
|
|
* Explicit pagetable population and nonlinear (random) mappings support.
|
|
*
|
|
* started by Ingo Molnar, Copyright (C) 2002, 2003
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/file.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/swapops.h>
|
|
#include <linux/rmap.h>
|
|
#include <linux/module.h>
|
|
#include <linux/syscalls.h>
|
|
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
static int zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, pte_t *ptep)
|
|
{
|
|
pte_t pte = *ptep;
|
|
struct page *page = NULL;
|
|
|
|
if (pte_present(pte)) {
|
|
unsigned long pfn = pte_pfn(pte);
|
|
flush_cache_page(vma, addr, pfn);
|
|
pte = ptep_clear_flush(vma, addr, ptep);
|
|
if (unlikely(!pfn_valid(pfn))) {
|
|
print_bad_pte(vma, pte, addr);
|
|
goto out;
|
|
}
|
|
page = pfn_to_page(pfn);
|
|
if (pte_dirty(pte))
|
|
set_page_dirty(page);
|
|
page_remove_rmap(page);
|
|
page_cache_release(page);
|
|
} else {
|
|
if (!pte_file(pte))
|
|
free_swap_and_cache(pte_to_swp_entry(pte));
|
|
pte_clear(mm, addr, ptep);
|
|
}
|
|
out:
|
|
return !!page;
|
|
}
|
|
|
|
/*
|
|
* Install a file page to a given virtual memory address, release any
|
|
* previously existing mapping.
|
|
*/
|
|
int install_page(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, struct page *page, pgprot_t prot)
|
|
{
|
|
struct inode *inode;
|
|
pgoff_t size;
|
|
int err = -ENOMEM;
|
|
pte_t *pte;
|
|
pmd_t *pmd;
|
|
pud_t *pud;
|
|
pgd_t *pgd;
|
|
pte_t pte_val;
|
|
spinlock_t *ptl;
|
|
|
|
BUG_ON(vma->vm_flags & VM_UNPAGED);
|
|
|
|
pgd = pgd_offset(mm, addr);
|
|
pud = pud_alloc(mm, pgd, addr);
|
|
if (!pud)
|
|
goto out;
|
|
pmd = pmd_alloc(mm, pud, addr);
|
|
if (!pmd)
|
|
goto out;
|
|
pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
|
|
if (!pte)
|
|
goto out;
|
|
|
|
/*
|
|
* This page may have been truncated. Tell the
|
|
* caller about it.
|
|
*/
|
|
err = -EINVAL;
|
|
inode = vma->vm_file->f_mapping->host;
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
if (!page->mapping || page->index >= size)
|
|
goto unlock;
|
|
err = -ENOMEM;
|
|
if (page_mapcount(page) > INT_MAX/2)
|
|
goto unlock;
|
|
|
|
if (pte_none(*pte) || !zap_pte(mm, vma, addr, pte))
|
|
inc_mm_counter(mm, file_rss);
|
|
|
|
flush_icache_page(vma, page);
|
|
set_pte_at(mm, addr, pte, mk_pte(page, prot));
|
|
page_add_file_rmap(page);
|
|
pte_val = *pte;
|
|
update_mmu_cache(vma, addr, pte_val);
|
|
err = 0;
|
|
unlock:
|
|
pte_unmap_unlock(pte, ptl);
|
|
out:
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(install_page);
|
|
|
|
/*
|
|
* Install a file pte to a given virtual memory address, release any
|
|
* previously existing mapping.
|
|
*/
|
|
int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long pgoff, pgprot_t prot)
|
|
{
|
|
int err = -ENOMEM;
|
|
pte_t *pte;
|
|
pmd_t *pmd;
|
|
pud_t *pud;
|
|
pgd_t *pgd;
|
|
pte_t pte_val;
|
|
spinlock_t *ptl;
|
|
|
|
BUG_ON(vma->vm_flags & VM_UNPAGED);
|
|
|
|
pgd = pgd_offset(mm, addr);
|
|
pud = pud_alloc(mm, pgd, addr);
|
|
if (!pud)
|
|
goto out;
|
|
pmd = pmd_alloc(mm, pud, addr);
|
|
if (!pmd)
|
|
goto out;
|
|
pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
|
|
if (!pte)
|
|
goto out;
|
|
|
|
if (!pte_none(*pte) && zap_pte(mm, vma, addr, pte)) {
|
|
update_hiwater_rss(mm);
|
|
dec_mm_counter(mm, file_rss);
|
|
}
|
|
|
|
set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
|
|
pte_val = *pte;
|
|
update_mmu_cache(vma, addr, pte_val);
|
|
pte_unmap_unlock(pte, ptl);
|
|
err = 0;
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/***
|
|
* sys_remap_file_pages - remap arbitrary pages of a shared backing store
|
|
* file within an existing vma.
|
|
* @start: start of the remapped virtual memory range
|
|
* @size: size of the remapped virtual memory range
|
|
* @prot: new protection bits of the range
|
|
* @pgoff: to be mapped page of the backing store file
|
|
* @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
|
|
*
|
|
* this syscall works purely via pagetables, so it's the most efficient
|
|
* way to map the same (large) file into a given virtual window. Unlike
|
|
* mmap()/mremap() it does not create any new vmas. The new mappings are
|
|
* also safe across swapout.
|
|
*
|
|
* NOTE: the 'prot' parameter right now is ignored, and the vma's default
|
|
* protection is used. Arbitrary protections might be implemented in the
|
|
* future.
|
|
*/
|
|
asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
|
|
unsigned long __prot, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct address_space *mapping;
|
|
unsigned long end = start + size;
|
|
struct vm_area_struct *vma;
|
|
int err = -EINVAL;
|
|
int has_write_lock = 0;
|
|
|
|
if (__prot)
|
|
return err;
|
|
/*
|
|
* Sanitize the syscall parameters:
|
|
*/
|
|
start = start & PAGE_MASK;
|
|
size = size & PAGE_MASK;
|
|
|
|
/* Does the address range wrap, or is the span zero-sized? */
|
|
if (start + size <= start)
|
|
return err;
|
|
|
|
/* Can we represent this offset inside this architecture's pte's? */
|
|
#if PTE_FILE_MAX_BITS < BITS_PER_LONG
|
|
if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
|
|
return err;
|
|
#endif
|
|
|
|
/* We need down_write() to change vma->vm_flags. */
|
|
down_read(&mm->mmap_sem);
|
|
retry:
|
|
vma = find_vma(mm, start);
|
|
|
|
/*
|
|
* Make sure the vma is shared, that it supports prefaulting,
|
|
* and that the remapped range is valid and fully within
|
|
* the single existing vma. vm_private_data is used as a
|
|
* swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED
|
|
* or VM_LOCKED, but VM_LOCKED could be revoked later on).
|
|
*/
|
|
if (vma && (vma->vm_flags & VM_SHARED) &&
|
|
(!vma->vm_private_data ||
|
|
(vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) &&
|
|
vma->vm_ops && vma->vm_ops->populate &&
|
|
end > start && start >= vma->vm_start &&
|
|
end <= vma->vm_end) {
|
|
|
|
/* Must set VM_NONLINEAR before any pages are populated. */
|
|
if (pgoff != linear_page_index(vma, start) &&
|
|
!(vma->vm_flags & VM_NONLINEAR)) {
|
|
if (!has_write_lock) {
|
|
up_read(&mm->mmap_sem);
|
|
down_write(&mm->mmap_sem);
|
|
has_write_lock = 1;
|
|
goto retry;
|
|
}
|
|
mapping = vma->vm_file->f_mapping;
|
|
spin_lock(&mapping->i_mmap_lock);
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma->vm_flags |= VM_NONLINEAR;
|
|
vma_prio_tree_remove(vma, &mapping->i_mmap);
|
|
vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
spin_unlock(&mapping->i_mmap_lock);
|
|
}
|
|
|
|
err = vma->vm_ops->populate(vma, start, size,
|
|
vma->vm_page_prot,
|
|
pgoff, flags & MAP_NONBLOCK);
|
|
|
|
/*
|
|
* We can't clear VM_NONLINEAR because we'd have to do
|
|
* it after ->populate completes, and that would prevent
|
|
* downgrading the lock. (Locks can't be upgraded).
|
|
*/
|
|
}
|
|
if (likely(!has_write_lock))
|
|
up_read(&mm->mmap_sem);
|
|
else
|
|
up_write(&mm->mmap_sem);
|
|
|
|
return err;
|
|
}
|
|
|