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guard page for stacks that grow upwards 

pa-risc and ia64 have stacks that grow upwards. Check that
they do not run into other mappings. By making VM_GROWSUP
0x0 on architectures that do not ever use it, we can avoid
some unpleasant #ifdefs in check_stack_guard_page().

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Luck, Tony 2010-08-24 11:44:18 -07:00 committed by Linus Torvalds
parent 9559fcdbff
commit 8ca3eb0809
3 changed files with 18 additions and 8 deletions
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8
include/linux/mm.h
View File

@ -78,7 +78,11 @@ extern unsigned int kobjsize(const void *objp);
#define VM_MAYSHARE 0x00000080
#define VM_GROWSDOWN 0x00000100 /* general info on the segment */
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
#define VM_GROWSUP 0x00000200
#else
#define VM_GROWSUP 0x00000000
#endif
#define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */
#define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */
@ -1330,8 +1334,10 @@ unsigned long ra_submit(struct file_ra_state *ra,
/* Do stack extension */
extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
#ifdef CONFIG_IA64
#if VM_GROWSUP
extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
#else
#define expand_upwards(vma, address) do { } while (0)
#endif
extern int expand_stack_downwards(struct vm_area_struct *vma,
unsigned long address);

15
mm/memory.c
View File

@ -2760,11 +2760,9 @@ out_release:
}
/*
* This is like a special single-page "expand_downwards()",
* except we must first make sure that 'address-PAGE_SIZE'
* This is like a special single-page "expand_{down|up}wards()",
* except we must first make sure that 'address{-|+}PAGE_SIZE'
* doesn't hit another vma.
*
* The "find_vma()" will do the right thing even if we wrap
*/
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
@ -2783,6 +2781,15 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
expand_stack(vma, address - PAGE_SIZE);
}
if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
struct vm_area_struct *next = vma->vm_next;
/* As VM_GROWSDOWN but s/below/above/ */
if (next && next->vm_start == address + PAGE_SIZE)
return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
expand_upwards(vma, address + PAGE_SIZE);
}
return 0;
}

3
mm/mmap.c
View File

@ -1716,9 +1716,6 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
* PA-RISC uses this for its stack; IA64 for its Register Backing Store.
* vma is the last one with address > vma->vm_end. Have to extend vma.
*/
#ifndef CONFIG_IA64
static
#endif
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
{
int error;