Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Set up the VMAs to tell the VM about the vDSO. |
| 3 | * Copyright 2007 Andi Kleen, SUSE Labs. |
| 4 | * Subject to the GPL, v.2 |
| 5 | */ |
| 6 | #include <linux/mm.h> |
Alexey Dobriyan | 4e950f6 | 2007-07-30 02:36:13 +0400 | [diff] [blame] | 7 | #include <linux/err.h> |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 8 | #include <linux/sched.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 9 | #include <linux/slab.h> |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 10 | #include <linux/init.h> |
| 11 | #include <linux/random.h> |
Jaswinder Singh Rajput | 3fa89ca | 2009-04-12 20:37:25 +0530 | [diff] [blame] | 12 | #include <linux/elf.h> |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 13 | #include <asm/vsyscall.h> |
| 14 | #include <asm/vgtod.h> |
| 15 | #include <asm/proto.h> |
Roland McGrath | 7f3646a | 2008-01-30 13:30:41 +0100 | [diff] [blame] | 16 | #include <asm/vdso.h> |
Andy Lutomirski | aafade2 | 2011-07-21 15:47:10 -0400 | [diff] [blame] | 17 | #include <asm/page.h> |
Roland McGrath | 7f3646a | 2008-01-30 13:30:41 +0100 | [diff] [blame] | 18 | |
Andy Lutomirski | b4b541a | 2014-03-17 23:22:08 +0100 | [diff] [blame] | 19 | #if defined(CONFIG_X86_64) |
Andy Lutomirski | 3d7ee96 | 2014-05-05 12:19:32 -0700 | [diff] [blame] | 20 | unsigned int __read_mostly vdso64_enabled = 1; |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 21 | |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 22 | extern unsigned short vdso_sync_cpuid; |
Andy Lutomirski | b4b541a | 2014-03-17 23:22:08 +0100 | [diff] [blame] | 23 | #endif |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 24 | |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 25 | void __init init_vdso_image(const struct vdso_image *image) |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 26 | { |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 27 | int i; |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 28 | int npages = (image->size) / PAGE_SIZE; |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 29 | |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 30 | BUG_ON(image->size % PAGE_SIZE != 0); |
| 31 | for (i = 0; i < npages; i++) |
| 32 | image->pages[i] = virt_to_page(image->data + i*PAGE_SIZE); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 33 | |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 34 | apply_alternatives((struct alt_instr *)(image->data + image->alt), |
| 35 | (struct alt_instr *)(image->data + image->alt + |
| 36 | image->alt_len)); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 37 | } |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 38 | |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 39 | |
Andy Lutomirski | b4b541a | 2014-03-17 23:22:08 +0100 | [diff] [blame] | 40 | #if defined(CONFIG_X86_64) |
Andy Lutomirski | aafade2 | 2011-07-21 15:47:10 -0400 | [diff] [blame] | 41 | static int __init init_vdso(void) |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 42 | { |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 43 | init_vdso_image(&vdso_image_64); |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 44 | |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 45 | #ifdef CONFIG_X86_X32_ABI |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 46 | init_vdso_image(&vdso_image_x32); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 47 | #endif |
| 48 | |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 49 | return 0; |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 50 | } |
Andy Lutomirski | aafade2 | 2011-07-21 15:47:10 -0400 | [diff] [blame] | 51 | subsys_initcall(init_vdso); |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 52 | |
| 53 | struct linux_binprm; |
| 54 | |
| 55 | /* Put the vdso above the (randomized) stack with another randomized offset. |
| 56 | This way there is no hole in the middle of address space. |
| 57 | To save memory make sure it is still in the same PTE as the stack top. |
| 58 | This doesn't give that many random bits */ |
| 59 | static unsigned long vdso_addr(unsigned long start, unsigned len) |
| 60 | { |
| 61 | unsigned long addr, end; |
| 62 | unsigned offset; |
| 63 | end = (start + PMD_SIZE - 1) & PMD_MASK; |
Ingo Molnar | d951734 | 2009-02-20 23:32:28 +0100 | [diff] [blame] | 64 | if (end >= TASK_SIZE_MAX) |
| 65 | end = TASK_SIZE_MAX; |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 66 | end -= len; |
| 67 | /* This loses some more bits than a modulo, but is cheaper */ |
| 68 | offset = get_random_int() & (PTRS_PER_PTE - 1); |
| 69 | addr = start + (offset << PAGE_SHIFT); |
| 70 | if (addr >= end) |
| 71 | addr = end; |
Borislav Petkov | dfb09f9 | 2011-08-05 15:15:08 +0200 | [diff] [blame] | 72 | |
| 73 | /* |
| 74 | * page-align it here so that get_unmapped_area doesn't |
| 75 | * align it wrongfully again to the next page. addr can come in 4K |
| 76 | * unaligned here as a result of stack start randomization. |
| 77 | */ |
| 78 | addr = PAGE_ALIGN(addr); |
Michel Lespinasse | f9902472 | 2012-12-11 16:01:52 -0800 | [diff] [blame] | 79 | addr = align_vdso_addr(addr); |
Borislav Petkov | dfb09f9 | 2011-08-05 15:15:08 +0200 | [diff] [blame] | 80 | |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 81 | return addr; |
| 82 | } |
| 83 | |
| 84 | /* Setup a VMA at program startup for the vsyscall page. |
| 85 | Not called for compat tasks */ |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 86 | static int setup_additional_pages(struct linux_binprm *bprm, |
| 87 | int uses_interp, |
| 88 | struct page **pages, |
| 89 | unsigned size) |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 90 | { |
| 91 | struct mm_struct *mm = current->mm; |
| 92 | unsigned long addr; |
| 93 | int ret; |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 94 | |
Andy Lutomirski | 3d7ee96 | 2014-05-05 12:19:32 -0700 | [diff] [blame] | 95 | if (!vdso64_enabled) |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 96 | return 0; |
| 97 | |
| 98 | down_write(&mm->mmap_sem); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 99 | addr = vdso_addr(mm->start_stack, size); |
| 100 | addr = get_unmapped_area(NULL, addr, size, 0, 0); |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 101 | if (IS_ERR_VALUE(addr)) { |
| 102 | ret = addr; |
| 103 | goto up_fail; |
| 104 | } |
| 105 | |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 106 | current->mm->context.vdso = (void __user *)addr; |
Peter Zijlstra | f7b6eb3 | 2009-06-05 14:04:51 +0200 | [diff] [blame] | 107 | |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 108 | ret = install_special_mapping(mm, addr, size, |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 109 | VM_READ|VM_EXEC| |
Jason Baron | 909af76 | 2012-03-23 15:02:51 -0700 | [diff] [blame] | 110 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 111 | pages); |
Peter Zijlstra | f7b6eb3 | 2009-06-05 14:04:51 +0200 | [diff] [blame] | 112 | if (ret) { |
| 113 | current->mm->context.vdso = NULL; |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 114 | goto up_fail; |
Peter Zijlstra | f7b6eb3 | 2009-06-05 14:04:51 +0200 | [diff] [blame] | 115 | } |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 116 | |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 117 | up_fail: |
| 118 | up_write(&mm->mmap_sem); |
| 119 | return ret; |
| 120 | } |
| 121 | |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 122 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| 123 | { |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 124 | return setup_additional_pages(bprm, uses_interp, vdso_image_64.pages, |
| 125 | vdso_image_64.size); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 126 | } |
| 127 | |
| 128 | #ifdef CONFIG_X86_X32_ABI |
| 129 | int x32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| 130 | { |
Andy Lutomirski | 6f121e5 | 2014-05-05 12:19:34 -0700 | [diff] [blame^] | 131 | return setup_additional_pages(bprm, uses_interp, vdso_image_x32.pages, |
| 132 | vdso_image_x32.size); |
H. J. Lu | 1a21d4e | 2012-02-19 11:38:06 -0800 | [diff] [blame] | 133 | } |
| 134 | #endif |
| 135 | |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 136 | static __init int vdso_setup(char *s) |
| 137 | { |
Andy Lutomirski | 3d7ee96 | 2014-05-05 12:19:32 -0700 | [diff] [blame] | 138 | vdso64_enabled = simple_strtoul(s, NULL, 0); |
Andi Kleen | 2aae950 | 2007-07-21 17:10:01 +0200 | [diff] [blame] | 139 | return 0; |
| 140 | } |
| 141 | __setup("vdso=", vdso_setup); |
Andy Lutomirski | b4b541a | 2014-03-17 23:22:08 +0100 | [diff] [blame] | 142 | #endif |