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linux/include/asm-um/pgtable.h
Hugh Dickins 705e87c0c3 [PATCH] mm: pte_offset_map_lock loops 
Convert those common loops using page_table_lock on the outside and
pte_offset_map within to use just pte_offset_map_lock within instead.

These all hold mmap_sem (some exclusively, some not), so at no level can a
page table be whipped away from beneath them.  But whereas pte_alloc loops
tested with the "atomic" pmd_present, these loops are testing with pmd_none,
which on i386 PAE tests both lower and upper halves.

That's now unsafe, so add a cast into pmd_none to test only the vital lower
half: we lose a little sensitivity to a corrupt middle directory, but not
enough to worry about.  It appears that i386 and UML were the only
architectures vulnerable in this way, and pgd and pud no problem.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:40 -07:00

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/*
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Copyright 2003 PathScale, Inc.
* Derived from include/asm-i386/pgtable.h
* Licensed under the GPL
*/
#ifndef __UM_PGTABLE_H
#define __UM_PGTABLE_H
#include "linux/sched.h"
#include "linux/linkage.h"
#include "asm/processor.h"
#include "asm/page.h"
#include "asm/fixmap.h"
#define _PAGE_PRESENT 0x001
#define _PAGE_NEWPAGE 0x002
#define _PAGE_NEWPROT 0x004
#define _PAGE_RW 0x020
#define _PAGE_USER 0x040
#define _PAGE_ACCESSED 0x080
#define _PAGE_DIRTY 0x100
/* If _PAGE_PRESENT is clear, we use these: */
#define _PAGE_FILE 0x008 /* nonlinear file mapping, saved PTE; unset:swap */
#define _PAGE_PROTNONE 0x010 /* if the user mapped it with PROT_NONE;
pte_present gives true */
#ifdef CONFIG_3_LEVEL_PGTABLES
#include "asm/pgtable-3level.h"
#else
#include "asm/pgtable-2level.h"
#endif
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern void *um_virt_to_phys(struct task_struct *task, unsigned long virt,
pte_t *pte_out);
/* zero page used for uninitialized stuff */
extern unsigned long *empty_zero_page;
#define pgtable_cache_init() do ; while (0)
/*
* pgd entries used up by user/kernel:
*/
#define USER_PGD_PTRS (TASK_SIZE >> PGDIR_SHIFT)
#define KERNEL_PGD_PTRS (PTRS_PER_PGD-USER_PGD_PTRS)
#ifndef __ASSEMBLY__
/* Just any arbitrary offset to the start of the vmalloc VM area: the
* current 8MB value just means that there will be a 8MB "hole" after the
* physical memory until the kernel virtual memory starts. That means that
* any out-of-bounds memory accesses will hopefully be caught.
* The vmalloc() routines leaves a hole of 4kB between each vmalloced
* area for the same reason. ;)
*/
extern unsigned long end_iomem;
#define VMALLOC_OFFSET (__va_space)
#define VMALLOC_START ((end_iomem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
#ifdef CONFIG_HIGHMEM
# define VMALLOC_END (PKMAP_BASE-2*PAGE_SIZE)
#else
# define VMALLOC_END (FIXADDR_START-2*PAGE_SIZE)
#endif
#define REGION_SHIFT (sizeof(pte_t) * 8 - 4)
#define REGION_MASK (((unsigned long) 0xf) << REGION_SHIFT)
#define _PAGE_TABLE (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _KERNPG_TABLE (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
#define PAGE_KERNEL_RO __pgprot(_PAGE_PRESENT | _PAGE_DIRTY | _PAGE_ACCESSED)
/*
* The i386 can't do page protection for execute, and considers that the same are read.
* Also, write permissions imply read permissions. This is the closest we can get..
*/
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY
#define __P100 PAGE_READONLY
#define __P101 PAGE_READONLY
#define __P110 PAGE_COPY
#define __P111 PAGE_COPY
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY
#define __S010 PAGE_SHARED
#define __S011 PAGE_SHARED
#define __S100 PAGE_READONLY
#define __S101 PAGE_READONLY
#define __S110 PAGE_SHARED
#define __S111 PAGE_SHARED
/*
* Define this if things work differently on an i386 and an i486:
* it will (on an i486) warn about kernel memory accesses that are
* done without a 'access_ok(VERIFY_WRITE,..)'
*/
#undef TEST_VERIFY_AREA
/* page table for 0-4MB for everybody */
extern unsigned long pg0[1024];
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
#define ZERO_PAGE(vaddr) virt_to_page(empty_zero_page)
/* number of bits that fit into a memory pointer */
#define BITS_PER_PTR (8*sizeof(unsigned long))
/* to align the pointer to a pointer address */
#define PTR_MASK (~(sizeof(void*)-1))
/* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
/* 64-bit machines, beware! SRB. */
#define SIZEOF_PTR_LOG2 3
/* to find an entry in a page-table */
#define PAGE_PTR(address) \
((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
#define pte_clear(mm,addr,xp) pte_set_val(*(xp), (phys_t) 0, __pgprot(_PAGE_NEWPAGE))
#define pmd_none(x) (!((unsigned long)pmd_val(x) & ~_PAGE_NEWPAGE))
#define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
#define pmd_present(x) (pmd_val(x) & _PAGE_PRESENT)
#define pmd_clear(xp) do { pmd_val(*(xp)) = _PAGE_NEWPAGE; } while (0)
#define pmd_newpage(x) (pmd_val(x) & _PAGE_NEWPAGE)
#define pmd_mkuptodate(x) (pmd_val(x) &= ~_PAGE_NEWPAGE)
#define pud_newpage(x) (pud_val(x) & _PAGE_NEWPAGE)
#define pud_mkuptodate(x) (pud_val(x) &= ~_PAGE_NEWPAGE)
#define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))
#define pmd_page(pmd) phys_to_page(pmd_val(pmd) & PAGE_MASK)
#define pte_page(x) pfn_to_page(pte_pfn(x))
#define pte_address(x) (__va(pte_val(x) & PAGE_MASK))
#define mk_phys(a, r) ((a) + (((unsigned long) r) << REGION_SHIFT))
#define phys_addr(p) ((p) & ~REGION_MASK)
#define pte_present(x) pte_get_bits(x, (_PAGE_PRESENT | _PAGE_PROTNONE))
/*
* =================================
* Flags checking section.
* =================================
*/
static inline int pte_none(pte_t pte)
{
return pte_is_zero(pte);
}
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
static inline int pte_user(pte_t pte)
{
return((pte_get_bits(pte, _PAGE_USER)) &&
!(pte_get_bits(pte, _PAGE_PROTNONE)));
}
static inline int pte_read(pte_t pte)
{
return((pte_get_bits(pte, _PAGE_USER)) &&
!(pte_get_bits(pte, _PAGE_PROTNONE)));
}
static inline int pte_exec(pte_t pte){
return((pte_get_bits(pte, _PAGE_USER)) &&
!(pte_get_bits(pte, _PAGE_PROTNONE)));
}
static inline int pte_write(pte_t pte)
{
return((pte_get_bits(pte, _PAGE_RW)) &&
!(pte_get_bits(pte, _PAGE_PROTNONE)));
}
/*
* The following only works if pte_present() is not true.
*/
static inline int pte_file(pte_t pte)
{
return pte_get_bits(pte, _PAGE_FILE);
}
static inline int pte_dirty(pte_t pte)
{
return pte_get_bits(pte, _PAGE_DIRTY);
}
static inline int pte_young(pte_t pte)
{
return pte_get_bits(pte, _PAGE_ACCESSED);
}
static inline int pte_newpage(pte_t pte)
{
return pte_get_bits(pte, _PAGE_NEWPAGE);
}
static inline int pte_newprot(pte_t pte)
{
return(pte_present(pte) && (pte_get_bits(pte, _PAGE_NEWPROT)));
}
/*
* =================================
* Flags setting section.
* =================================
*/
static inline pte_t pte_mknewprot(pte_t pte)
{
pte_set_bits(pte, _PAGE_NEWPROT);
return(pte);
}
static inline pte_t pte_rdprotect(pte_t pte)
{
pte_clear_bits(pte, _PAGE_USER);
return(pte_mknewprot(pte));
}
static inline pte_t pte_exprotect(pte_t pte)
{
pte_clear_bits(pte, _PAGE_USER);
return(pte_mknewprot(pte));
}
static inline pte_t pte_mkclean(pte_t pte)
{
pte_clear_bits(pte, _PAGE_DIRTY);
return(pte);
}
static inline pte_t pte_mkold(pte_t pte)
{
pte_clear_bits(pte, _PAGE_ACCESSED);
return(pte);
}
static inline pte_t pte_wrprotect(pte_t pte)
{
pte_clear_bits(pte, _PAGE_RW);
return(pte_mknewprot(pte));
}
static inline pte_t pte_mkread(pte_t pte)
{
pte_set_bits(pte, _PAGE_RW);
return(pte_mknewprot(pte));
}
static inline pte_t pte_mkexec(pte_t pte)
{
pte_set_bits(pte, _PAGE_USER);
return(pte_mknewprot(pte));
}
static inline pte_t pte_mkdirty(pte_t pte)
{
pte_set_bits(pte, _PAGE_DIRTY);
return(pte);
}
static inline pte_t pte_mkyoung(pte_t pte)
{
pte_set_bits(pte, _PAGE_ACCESSED);
return(pte);
}
static inline pte_t pte_mkwrite(pte_t pte)
{
pte_set_bits(pte, _PAGE_RW);
return(pte_mknewprot(pte));
}
static inline pte_t pte_mkuptodate(pte_t pte)
{
pte_clear_bits(pte, _PAGE_NEWPAGE);
if(pte_present(pte))
pte_clear_bits(pte, _PAGE_NEWPROT);
return(pte);
}
static inline pte_t pte_mknewpage(pte_t pte)
{
pte_set_bits(pte, _PAGE_NEWPAGE);
return(pte);
}
static inline void set_pte(pte_t *pteptr, pte_t pteval)
{
pte_copy(*pteptr, pteval);
/* If it's a swap entry, it needs to be marked _PAGE_NEWPAGE so
* fix_range knows to unmap it. _PAGE_NEWPROT is specific to
* mapped pages.
*/
*pteptr = pte_mknewpage(*pteptr);
if(pte_present(*pteptr)) *pteptr = pte_mknewprot(*pteptr);
}
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
#define __virt_to_page(virt) phys_to_page(__pa(virt))
#define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
#define mk_pte(page, pgprot) \
({ pte_t pte; \
\
pte_set_val(pte, page_to_phys(page), (pgprot)); \
if (pte_present(pte)) \
pte_mknewprot(pte_mknewpage(pte)); \
pte;})
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte_set_val(pte, (pte_val(pte) & _PAGE_CHG_MASK), newprot);
return pte;
}
#define pmd_page_kernel(pmd) ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
/*
* the pgd page can be thought of an array like this: pgd_t[PTRS_PER_PGD]
*
* this macro returns the index of the entry in the pgd page which would
* control the given virtual address
*/
#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
#define pgd_index_k(addr) pgd_index(addr)
/*
* pgd_offset() returns a (pgd_t *)
* pgd_index() is used get the offset into the pgd page's array of pgd_t's;
*/
#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))
/*
* a shortcut which implies the use of the kernel's pgd, instead
* of a process's
*/
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
/*
* the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
*
* this macro returns the index of the entry in the pmd page which would
* control the given virtual address
*/
#define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
/*
* the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
*
* this macro returns the index of the entry in the pte page which would
* control the given virtual address
*/
#define pte_index(address) (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, address) \
((pte_t *) pmd_page_kernel(*(dir)) + pte_index(address))
#define pte_offset_map(dir, address) \
((pte_t *)page_address(pmd_page(*(dir))) + pte_index(address))
#define pte_offset_map_nested(dir, address) pte_offset_map(dir, address)
#define pte_unmap(pte) do { } while (0)
#define pte_unmap_nested(pte) do { } while (0)
#define update_mmu_cache(vma,address,pte) do ; while (0)
/* Encode and de-code a swap entry */
#define __swp_type(x) (((x).val >> 4) & 0x3f)
#define __swp_offset(x) ((x).val >> 11)
#define __swp_entry(type, offset) \
((swp_entry_t) { ((type) << 4) | ((offset) << 11) })
#define __pte_to_swp_entry(pte) \
((swp_entry_t) { pte_val(pte_mkuptodate(pte)) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#define kern_addr_valid(addr) (1)
#include <asm-generic/pgtable.h>
#include <asm-generic/pgtable-nopud.h>
#endif
#endif
#define virt_to_page(addr) __virt_to_page((const unsigned long) addr)
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/
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