| From 8ca3eb08097f6839b2206e2242db4179aee3cfb3 Mon Sep 17 00:00:00 2001 |
| From: Luck, Tony <tony.luck@intel.com> |
| Date: Tue, 24 Aug 2010 11:44:18 -0700 |
| Subject: guard page for stacks that grow upwards |
| |
| From: Luck, Tony <tony.luck@intel.com> |
| |
| commit 8ca3eb08097f6839b2206e2242db4179aee3cfb3 upstream. |
| |
| 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> |
| Cc: dann frazier <dannf@debian.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| include/linux/mm.h | 8 +++++++- |
| mm/memory.c | 15 +++++++++++---- |
| mm/mmap.c | 3 --- |
| 3 files changed, 18 insertions(+), 8 deletions(-) |
| |
| --- a/include/linux/mm.h |
| +++ b/include/linux/mm.h |
| @@ -77,7 +77,11 @@ extern unsigned int kobjsize(const void |
| #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.. */ |
| |
| @@ -1195,8 +1199,10 @@ unsigned long ra_submit(struct file_ra_s |
| |
| /* 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); |
| --- a/mm/memory.c |
| +++ b/mm/memory.c |
| @@ -2630,11 +2630,9 @@ 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) |
| { |
| @@ -2653,6 +2651,15 @@ static inline int check_stack_guard_page |
| |
| 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; |
| } |
| |
| --- a/mm/mmap.c |
| +++ b/mm/mmap.c |
| @@ -1600,9 +1600,6 @@ static int acct_stack_growth(struct vm_a |
| * 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; |