diff options
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/process.c | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 46fbbb3701a..edd2ac3d7c4 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -475,6 +475,39 @@ const char *arch_vma_name(struct vm_area_struct *vma) return is_gate_vma(vma) ? "[vectors]" : NULL; } +/* If possible, provide a placement hint at a random offset from the + * stack for the signal page. + */ +static unsigned long sigpage_addr(const struct mm_struct *mm, + unsigned int npages) +{ + unsigned long offset; + unsigned long first; + unsigned long last; + unsigned long addr; + unsigned int slots; + + first = PAGE_ALIGN(mm->start_stack); + + last = TASK_SIZE - (npages << PAGE_SHIFT); + + /* No room after stack? */ + if (first > last) + return 0; + + /* Just enough room? */ + if (first == last) + return first; + + slots = ((last - first) >> PAGE_SHIFT) + 1; + + offset = get_random_int() % slots; + + addr = first + (offset << PAGE_SHIFT); + + return addr; +} + static struct page *signal_page; extern struct page *get_signal_page(void); @@ -488,6 +521,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) struct mm_struct *mm = current->mm; struct vm_area_struct *vma; unsigned long addr; + unsigned long hint; int ret = 0; if (!signal_page) @@ -496,7 +530,8 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) return -ENOMEM; down_write(&mm->mmap_sem); - addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); + hint = sigpage_addr(mm, 1); + addr = get_unmapped_area(NULL, hint, PAGE_SIZE, 0, 0); if (IS_ERR_VALUE(addr)) { ret = addr; goto up_fail; |