diff options
| -rw-r--r-- | arch/x86/entry/vdso/vma.c | 98 |
1 files changed, 48 insertions, 50 deletions
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 4459e73e234d..23c881caabd1 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -37,54 +37,6 @@ void __init init_vdso_image(const struct vdso_image *image) struct linux_binprm; -/* - * Put the vdso above the (randomized) stack with another randomized - * offset. This way there is no hole in the middle of address space. - * To save memory make sure it is still in the same PTE as the stack - * top. This doesn't give that many random bits. - * - * Note that this algorithm is imperfect: the distribution of the vdso - * start address within a PMD is biased toward the end. - * - * Only used for the 64-bit and x32 vdsos. - */ -static unsigned long vdso_addr(unsigned long start, unsigned len) -{ -#ifdef CONFIG_X86_32 - return 0; -#else - unsigned long addr, end; - unsigned offset; - - /* - * Round up the start address. It can start out unaligned as a result - * of stack start randomization. - */ - start = PAGE_ALIGN(start); - - /* Round the lowest possible end address up to a PMD boundary. */ - end = (start + len + PMD_SIZE - 1) & PMD_MASK; - if (end >= TASK_SIZE_MAX) - end = TASK_SIZE_MAX; - end -= len; - - if (end > start) { - offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1); - addr = start + (offset << PAGE_SHIFT); - } else { - addr = start; - } - - /* - * Forcibly align the final address in case we have a hardware - * issue that requires alignment for performance reasons. - */ - addr = align_vdso_addr(addr); - - return addr; -#endif -} - static int vdso_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) { @@ -249,12 +201,58 @@ up_fail: return ret; } +#ifdef CONFIG_X86_64 +/* + * Put the vdso above the (randomized) stack with another randomized + * offset. This way there is no hole in the middle of address space. + * To save memory make sure it is still in the same PTE as the stack + * top. This doesn't give that many random bits. + * + * Note that this algorithm is imperfect: the distribution of the vdso + * start address within a PMD is biased toward the end. + * + * Only used for the 64-bit and x32 vdsos. + */ +static unsigned long vdso_addr(unsigned long start, unsigned len) +{ + unsigned long addr, end; + unsigned offset; + + /* + * Round up the start address. It can start out unaligned as a result + * of stack start randomization. + */ + start = PAGE_ALIGN(start); + + /* Round the lowest possible end address up to a PMD boundary. */ + end = (start + len + PMD_SIZE - 1) & PMD_MASK; + if (end >= TASK_SIZE_MAX) + end = TASK_SIZE_MAX; + end -= len; + + if (end > start) { + offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1); + addr = start + (offset << PAGE_SHIFT); + } else { + addr = start; + } + + /* + * Forcibly align the final address in case we have a hardware + * issue that requires alignment for performance reasons. + */ + addr = align_vdso_addr(addr); + + return addr; +} + static int map_vdso_randomized(const struct vdso_image *image) { - unsigned long addr = vdso_addr(current->mm->start_stack, - image->size - image->sym_vvar_start); + unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start); + return map_vdso(image, addr); } +#endif int map_vdso_once(const struct vdso_image *image, unsigned long addr) { |