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Commit 8ca3eb08 authored by Tony Luck's avatar Tony Luck Committed by Linus Torvalds
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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: default avatarTony Luck <tony.luck@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9559fcdb

include/linux/mm.h

+7 −1
Original line number Diff line number Diff line
@@ -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);

mm/memory.c

+11 −4
Original line number Diff line number Diff line
@@ -2760,11 +2760,9 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 
}



/*

 * 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;

}

mm/mmap.c

+0 −3
Original line number Diff line number Diff line
@@ -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;