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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2002 Jeff Dike (jdike@karaya.com) | |
3 | * Licensed under the GPL | |
4 | */ | |
5 | ||
d67b569f | 6 | #include "linux/config.h" |
1da177e4 LT |
7 | #include "linux/sched.h" |
8 | #include "linux/list.h" | |
9 | #include "linux/spinlock.h" | |
10 | #include "linux/slab.h" | |
d67b569f JD |
11 | #include "linux/errno.h" |
12 | #include "linux/mm.h" | |
1da177e4 LT |
13 | #include "asm/current.h" |
14 | #include "asm/segment.h" | |
15 | #include "asm/mmu.h" | |
d67b569f JD |
16 | #include "asm/pgalloc.h" |
17 | #include "asm/pgtable.h" | |
1da177e4 LT |
18 | #include "os.h" |
19 | #include "skas.h" | |
20 | ||
d67b569f JD |
21 | extern int __syscall_stub_start; |
22 | ||
23 | static int init_stub_pte(struct mm_struct *mm, unsigned long proc, | |
24 | unsigned long kernel) | |
25 | { | |
26 | pgd_t *pgd; | |
27 | pud_t *pud; | |
28 | pmd_t *pmd; | |
29 | pte_t *pte; | |
30 | ||
d67b569f JD |
31 | pgd = pgd_offset(mm, proc); |
32 | pud = pud_alloc(mm, pgd, proc); | |
33 | if (!pud) | |
34 | goto out; | |
35 | ||
36 | pmd = pmd_alloc(mm, pud, proc); | |
37 | if (!pmd) | |
38 | goto out_pmd; | |
39 | ||
40 | pte = pte_alloc_map(mm, pmd, proc); | |
41 | if (!pte) | |
42 | goto out_pte; | |
43 | ||
44 | /* There's an interaction between the skas0 stub pages, stack | |
45 | * randomization, and the BUG at the end of exit_mmap. exit_mmap | |
46 | * checks that the number of page tables freed is the same as had | |
47 | * been allocated. If the stack is on the last page table page, | |
48 | * then the stack pte page will be freed, and if not, it won't. To | |
49 | * avoid having to know where the stack is, or if the process mapped | |
50 | * something at the top of its address space for some other reason, | |
51 | * we set TASK_SIZE to end at the start of the last page table. | |
52 | * This keeps exit_mmap off the last page, but introduces a leak | |
53 | * of that page. So, we hang onto it here and free it in | |
54 | * destroy_context_skas. | |
55 | */ | |
56 | ||
57 | mm->context.skas.last_page_table = pmd_page_kernel(*pmd); | |
7ef93905 JD |
58 | #ifdef CONFIG_3_LEVEL_PGTABLES |
59 | mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud)); | |
60 | #endif | |
d67b569f JD |
61 | |
62 | *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); | |
63 | *pte = pte_mkexec(*pte); | |
64 | *pte = pte_wrprotect(*pte); | |
d67b569f JD |
65 | return(0); |
66 | ||
67 | out_pmd: | |
68 | pud_free(pud); | |
69 | out_pte: | |
70 | pmd_free(pmd); | |
71 | out: | |
d67b569f JD |
72 | return(-ENOMEM); |
73 | } | |
74 | ||
1da177e4 LT |
75 | int init_new_context_skas(struct task_struct *task, struct mm_struct *mm) |
76 | { | |
d67b569f | 77 | struct mm_struct *cur_mm = current->mm; |
9786a8f3 | 78 | struct mm_id *cur_mm_id = &cur_mm->context.skas.id; |
d67b569f | 79 | struct mm_id *mm_id = &mm->context.skas.id; |
8b51304e BS |
80 | unsigned long stack = 0; |
81 | int from, ret = -ENOMEM; | |
1da177e4 | 82 | |
8b51304e BS |
83 | if(!proc_mm || !ptrace_faultinfo){ |
84 | stack = get_zeroed_page(GFP_KERNEL); | |
85 | if(stack == 0) | |
86 | goto out; | |
1da177e4 | 87 | |
d67b569f JD |
88 | /* This zeros the entry that pgd_alloc didn't, needed since |
89 | * we are about to reinitialize it, and want mm.nr_ptes to | |
90 | * be accurate. | |
91 | */ | |
92 | mm->pgd[USER_PTRS_PER_PGD] = __pgd(0); | |
1da177e4 | 93 | |
d67b569f JD |
94 | ret = init_stub_pte(mm, CONFIG_STUB_CODE, |
95 | (unsigned long) &__syscall_stub_start); | |
96 | if(ret) | |
8b51304e | 97 | goto out_free; |
d67b569f JD |
98 | |
99 | ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack); | |
100 | if(ret) | |
101 | goto out_free; | |
102 | ||
103 | mm->nr_ptes--; | |
8b51304e BS |
104 | } |
105 | mm_id->stack = stack; | |
9786a8f3 | 106 | |
8b51304e BS |
107 | if(proc_mm){ |
108 | if((cur_mm != NULL) && (cur_mm != &init_mm)) | |
109 | from = cur_mm_id->u.mm_fd; | |
110 | else from = -1; | |
111 | ||
112 | ret = new_mm(from, stack); | |
113 | if(ret < 0){ | |
114 | printk("init_new_context_skas - new_mm failed, " | |
115 | "errno = %d\n", ret); | |
116 | goto out_free; | |
117 | } | |
118 | mm_id->u.mm_fd = ret; | |
119 | } | |
120 | else { | |
9786a8f3 BS |
121 | if((cur_mm != NULL) && (cur_mm != &init_mm)) |
122 | mm_id->u.pid = copy_context_skas0(stack, | |
123 | cur_mm_id->u.pid); | |
124 | else mm_id->u.pid = start_userspace(stack); | |
d67b569f JD |
125 | } |
126 | ||
127 | return 0; | |
128 | ||
129 | out_free: | |
8b51304e BS |
130 | if(mm_id->stack != 0) |
131 | free_page(mm_id->stack); | |
d67b569f JD |
132 | out: |
133 | return ret; | |
1da177e4 LT |
134 | } |
135 | ||
136 | void destroy_context_skas(struct mm_struct *mm) | |
137 | { | |
d67b569f | 138 | struct mmu_context_skas *mmu = &mm->context.skas; |
1da177e4 | 139 | |
d67b569f JD |
140 | if(proc_mm) |
141 | os_close_file(mmu->id.u.mm_fd); | |
8b51304e | 142 | else |
d67b569f | 143 | os_kill_ptraced_process(mmu->id.u.pid, 1); |
8b51304e BS |
144 | |
145 | if(!proc_mm || !ptrace_faultinfo){ | |
d67b569f | 146 | free_page(mmu->id.stack); |
4c21e2f2 | 147 | pte_lock_deinit(virt_to_page(mmu->last_page_table)); |
7ef93905 JD |
148 | pte_free_kernel((pte_t *) mmu->last_page_table); |
149 | dec_page_state(nr_page_table_pages); | |
150 | #ifdef CONFIG_3_LEVEL_PGTABLES | |
151 | pmd_free((pmd_t *) mmu->last_pmd); | |
152 | #endif | |
d67b569f JD |
153 | } |
154 | } |