Commit | Line | Data |
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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" | |
858259cf | 18 | #include "asm/ldt.h" |
1da177e4 LT |
19 | #include "os.h" |
20 | #include "skas.h" | |
21 | ||
d67b569f JD |
22 | extern int __syscall_stub_start; |
23 | ||
24 | static int init_stub_pte(struct mm_struct *mm, unsigned long proc, | |
25 | unsigned long kernel) | |
26 | { | |
27 | pgd_t *pgd; | |
28 | pud_t *pud; | |
29 | pmd_t *pmd; | |
30 | pte_t *pte; | |
31 | ||
d67b569f JD |
32 | pgd = pgd_offset(mm, proc); |
33 | pud = pud_alloc(mm, pgd, proc); | |
34 | if (!pud) | |
35 | goto out; | |
36 | ||
37 | pmd = pmd_alloc(mm, pud, proc); | |
38 | if (!pmd) | |
39 | goto out_pmd; | |
40 | ||
41 | pte = pte_alloc_map(mm, pmd, proc); | |
42 | if (!pte) | |
43 | goto out_pte; | |
44 | ||
45 | /* There's an interaction between the skas0 stub pages, stack | |
46 | * randomization, and the BUG at the end of exit_mmap. exit_mmap | |
47 | * checks that the number of page tables freed is the same as had | |
48 | * been allocated. If the stack is on the last page table page, | |
49 | * then the stack pte page will be freed, and if not, it won't. To | |
50 | * avoid having to know where the stack is, or if the process mapped | |
51 | * something at the top of its address space for some other reason, | |
52 | * we set TASK_SIZE to end at the start of the last page table. | |
53 | * This keeps exit_mmap off the last page, but introduces a leak | |
54 | * of that page. So, we hang onto it here and free it in | |
55 | * destroy_context_skas. | |
56 | */ | |
57 | ||
46a82b2d | 58 | mm->context.skas.last_page_table = pmd_page_vaddr(*pmd); |
7ef93905 JD |
59 | #ifdef CONFIG_3_LEVEL_PGTABLES |
60 | mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud)); | |
61 | #endif | |
d67b569f JD |
62 | |
63 | *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); | |
5906e417 JD |
64 | /* This is wrong for the code page, but it doesn't matter since the |
65 | * stub is mapped by hand with the correct permissions. | |
66 | */ | |
67 | *pte = pte_mkwrite(*pte); | |
d67b569f JD |
68 | return(0); |
69 | ||
70 | out_pmd: | |
71 | pud_free(pud); | |
72 | out_pte: | |
73 | pmd_free(pmd); | |
74 | out: | |
d67b569f JD |
75 | return(-ENOMEM); |
76 | } | |
77 | ||
1da177e4 LT |
78 | int init_new_context_skas(struct task_struct *task, struct mm_struct *mm) |
79 | { | |
858259cf BS |
80 | struct mmu_context_skas *from_mm = NULL; |
81 | struct mmu_context_skas *to_mm = &mm->context.skas; | |
8b51304e | 82 | unsigned long stack = 0; |
12919aa6 | 83 | int ret = -ENOMEM; |
1da177e4 | 84 | |
858259cf | 85 | if(skas_needs_stub){ |
8b51304e BS |
86 | stack = get_zeroed_page(GFP_KERNEL); |
87 | if(stack == 0) | |
88 | goto out; | |
1da177e4 | 89 | |
d67b569f JD |
90 | /* This zeros the entry that pgd_alloc didn't, needed since |
91 | * we are about to reinitialize it, and want mm.nr_ptes to | |
92 | * be accurate. | |
93 | */ | |
94 | mm->pgd[USER_PTRS_PER_PGD] = __pgd(0); | |
1da177e4 | 95 | |
d67b569f JD |
96 | ret = init_stub_pte(mm, CONFIG_STUB_CODE, |
97 | (unsigned long) &__syscall_stub_start); | |
98 | if(ret) | |
8b51304e | 99 | goto out_free; |
d67b569f JD |
100 | |
101 | ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack); | |
102 | if(ret) | |
103 | goto out_free; | |
104 | ||
105 | mm->nr_ptes--; | |
8b51304e | 106 | } |
858259cf BS |
107 | |
108 | to_mm->id.stack = stack; | |
109 | if(current->mm != NULL && current->mm != &init_mm) | |
110 | from_mm = ¤t->mm->context.skas; | |
9786a8f3 | 111 | |
8b51304e | 112 | if(proc_mm){ |
12919aa6 | 113 | ret = new_mm(stack); |
8b51304e BS |
114 | if(ret < 0){ |
115 | printk("init_new_context_skas - new_mm failed, " | |
116 | "errno = %d\n", ret); | |
117 | goto out_free; | |
118 | } | |
858259cf | 119 | to_mm->id.u.mm_fd = ret; |
8b51304e BS |
120 | } |
121 | else { | |
858259cf BS |
122 | if(from_mm) |
123 | to_mm->id.u.pid = copy_context_skas0(stack, | |
124 | from_mm->id.u.pid); | |
125 | else to_mm->id.u.pid = start_userspace(stack); | |
126 | } | |
127 | ||
128 | ret = init_new_ldt(to_mm, from_mm); | |
129 | if(ret < 0){ | |
130 | printk("init_new_context_skas - init_ldt" | |
131 | " failed, errno = %d\n", ret); | |
132 | goto out_free; | |
d67b569f JD |
133 | } |
134 | ||
135 | return 0; | |
136 | ||
137 | out_free: | |
858259cf BS |
138 | if(to_mm->id.stack != 0) |
139 | free_page(to_mm->id.stack); | |
d67b569f JD |
140 | out: |
141 | return ret; | |
1da177e4 LT |
142 | } |
143 | ||
144 | void destroy_context_skas(struct mm_struct *mm) | |
145 | { | |
d67b569f | 146 | struct mmu_context_skas *mmu = &mm->context.skas; |
1da177e4 | 147 | |
d67b569f JD |
148 | if(proc_mm) |
149 | os_close_file(mmu->id.u.mm_fd); | |
8b51304e | 150 | else |
d67b569f | 151 | os_kill_ptraced_process(mmu->id.u.pid, 1); |
8b51304e BS |
152 | |
153 | if(!proc_mm || !ptrace_faultinfo){ | |
d67b569f | 154 | free_page(mmu->id.stack); |
4c21e2f2 | 155 | pte_lock_deinit(virt_to_page(mmu->last_page_table)); |
7ef93905 | 156 | pte_free_kernel((pte_t *) mmu->last_page_table); |
df849a15 | 157 | dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE); |
7ef93905 JD |
158 | #ifdef CONFIG_3_LEVEL_PGTABLES |
159 | pmd_free((pmd_t *) mmu->last_pmd); | |
160 | #endif | |
d67b569f JD |
161 | } |
162 | } |