Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * Licensed under the GPL |
| 4 | */ |
| 5 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 6 | #include "linux/mm.h" |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 7 | #include "linux/sched.h" |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 8 | #include "asm/pgalloc.h" |
| 9 | #include "asm/pgtable.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | #include "os.h" |
| 11 | #include "skas.h" |
| 12 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 13 | extern int __syscall_stub_start; |
| 14 | |
| 15 | static int init_stub_pte(struct mm_struct *mm, unsigned long proc, |
| 16 | unsigned long kernel) |
| 17 | { |
| 18 | pgd_t *pgd; |
| 19 | pud_t *pud; |
| 20 | pmd_t *pmd; |
| 21 | pte_t *pte; |
| 22 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 23 | pgd = pgd_offset(mm, proc); |
| 24 | pud = pud_alloc(mm, pgd, proc); |
| 25 | if (!pud) |
| 26 | goto out; |
| 27 | |
| 28 | pmd = pmd_alloc(mm, pud, proc); |
| 29 | if (!pmd) |
| 30 | goto out_pmd; |
| 31 | |
| 32 | pte = pte_alloc_map(mm, pmd, proc); |
| 33 | if (!pte) |
| 34 | goto out_pte; |
| 35 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 36 | /* |
| 37 | * There's an interaction between the skas0 stub pages, stack |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 38 | * randomization, and the BUG at the end of exit_mmap. exit_mmap |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 39 | * checks that the number of page tables freed is the same as had |
| 40 | * been allocated. If the stack is on the last page table page, |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 41 | * then the stack pte page will be freed, and if not, it won't. To |
| 42 | * avoid having to know where the stack is, or if the process mapped |
| 43 | * something at the top of its address space for some other reason, |
| 44 | * we set TASK_SIZE to end at the start of the last page table. |
| 45 | * This keeps exit_mmap off the last page, but introduces a leak |
| 46 | * of that page. So, we hang onto it here and free it in |
| 47 | * destroy_context_skas. |
| 48 | */ |
| 49 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 50 | mm->context.skas.last_page_table = pmd_page_vaddr(*pmd); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 51 | #ifdef CONFIG_3_LEVEL_PGTABLES |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 52 | mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud)); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 53 | #endif |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 54 | |
| 55 | *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); |
Paolo 'Blaisorblade' Giarrusso | 21c935e | 2006-10-11 01:21:32 -0700 | [diff] [blame] | 56 | *pte = pte_mkread(*pte); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 57 | return 0; |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 58 | |
| 59 | out_pmd: |
| 60 | pud_free(pud); |
| 61 | out_pte: |
| 62 | pmd_free(pmd); |
| 63 | out: |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 64 | return -ENOMEM; |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 65 | } |
| 66 | |
Jeff Dike | 77bf440 | 2007-10-16 01:26:58 -0700 | [diff] [blame] | 67 | int init_new_context(struct task_struct *task, struct mm_struct *mm) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | { |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 69 | struct mmu_context_skas *from_mm = NULL; |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 70 | struct mmu_context_skas *to_mm = &mm->context.skas; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 71 | unsigned long stack = 0; |
Bodo Stroesser | 12919aa | 2006-01-18 17:42:39 -0800 | [diff] [blame] | 72 | int ret = -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 74 | if (skas_needs_stub) { |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 75 | stack = get_zeroed_page(GFP_KERNEL); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 76 | if (stack == 0) |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 77 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 79 | /* |
| 80 | * This zeros the entry that pgd_alloc didn't, needed since |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 81 | * we are about to reinitialize it, and want mm.nr_ptes to |
| 82 | * be accurate. |
| 83 | */ |
| 84 | mm->pgd[USER_PTRS_PER_PGD] = __pgd(0); |
| 85 | |
| 86 | ret = init_stub_pte(mm, CONFIG_STUB_CODE, |
| 87 | (unsigned long) &__syscall_stub_start); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 88 | if (ret) |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 89 | goto out_free; |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 90 | |
| 91 | ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 92 | if (ret) |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 93 | goto out_free; |
| 94 | |
| 95 | mm->nr_ptes--; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 96 | } |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 97 | |
| 98 | to_mm->id.stack = stack; |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 99 | if (current->mm != NULL && current->mm != &init_mm) |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 100 | from_mm = ¤t->mm->context.skas; |
Bodo Stroesser | 9786a8f | 2005-07-07 17:56:50 -0700 | [diff] [blame] | 101 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 102 | if (proc_mm) { |
Bodo Stroesser | 12919aa | 2006-01-18 17:42:39 -0800 | [diff] [blame] | 103 | ret = new_mm(stack); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 104 | if (ret < 0) { |
| 105 | printk(KERN_ERR "init_new_context_skas - " |
| 106 | "new_mm failed, errno = %d\n", ret); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 107 | goto out_free; |
| 108 | } |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 109 | to_mm->id.u.mm_fd = ret; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 110 | } |
| 111 | else { |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 112 | if (from_mm) |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 113 | to_mm->id.u.pid = copy_context_skas0(stack, |
| 114 | from_mm->id.u.pid); |
| 115 | else to_mm->id.u.pid = start_userspace(stack); |
| 116 | } |
| 117 | |
| 118 | ret = init_new_ldt(to_mm, from_mm); |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 119 | if (ret < 0) { |
| 120 | printk(KERN_ERR "init_new_context_skas - init_ldt" |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 121 | " failed, errno = %d\n", ret); |
| 122 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | } |
| 124 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 125 | return 0; |
| 126 | |
| 127 | out_free: |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 128 | if (to_mm->id.stack != 0) |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame] | 129 | free_page(to_mm->id.stack); |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 130 | out: |
| 131 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | } |
| 133 | |
Jeff Dike | 77bf440 | 2007-10-16 01:26:58 -0700 | [diff] [blame] | 134 | void destroy_context(struct mm_struct *mm) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | { |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 136 | struct mmu_context_skas *mmu = &mm->context.skas; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 138 | if (proc_mm) |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 139 | os_close_file(mmu->id.u.mm_fd); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 140 | else |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 141 | os_kill_ptraced_process(mmu->id.u.pid, 1); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 142 | |
Jeff Dike | ba180fd | 2007-10-16 01:27:00 -0700 | [diff] [blame^] | 143 | if (!proc_mm || !ptrace_faultinfo) { |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 144 | free_page(mmu->id.stack); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 145 | pte_lock_deinit(virt_to_page(mmu->last_page_table)); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 146 | pte_free_kernel((pte_t *) mmu->last_page_table); |
Christoph Lameter | df849a1 | 2006-06-30 01:55:38 -0700 | [diff] [blame] | 147 | dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 148 | #ifdef CONFIG_3_LEVEL_PGTABLES |
| 149 | pmd_free((pmd_t *) mmu->last_pmd); |
| 150 | #endif |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 151 | } |
| 152 | } |