1 /*
2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6 #include "linux/mm.h"
7 #include "linux/sched.h"
8 #include "asm/pgalloc.h"
9 #include "asm/pgtable.h"
10 #include "as-layout.h"
11 #include "os.h"
12 #include "skas.h"
13
14 extern int __syscall_stub_start;
15
init_stub_pte(struct mm_struct * mm,unsigned long proc,unsigned long kernel)16 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
17 unsigned long kernel)
18 {
19 pgd_t *pgd;
20 pud_t *pud;
21 pmd_t *pmd;
22 pte_t *pte;
23
24 pgd = pgd_offset(mm, proc);
25 pud = pud_alloc(mm, pgd, proc);
26 if (!pud)
27 goto out;
28
29 pmd = pmd_alloc(mm, pud, proc);
30 if (!pmd)
31 goto out_pmd;
32
33 pte = pte_alloc_map(mm, pmd, proc);
34 if (!pte)
35 goto out_pte;
36
37 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
38 *pte = pte_mkread(*pte);
39 return 0;
40
41 out_pmd:
42 pud_free(mm, pud);
43 out_pte:
44 pmd_free(mm, pmd);
45 out:
46 return -ENOMEM;
47 }
48
init_new_context(struct task_struct * task,struct mm_struct * mm)49 int init_new_context(struct task_struct *task, struct mm_struct *mm)
50 {
51 struct mm_context *from_mm = NULL;
52 struct mm_context *to_mm = &mm->context;
53 unsigned long stack = 0;
54 int ret = -ENOMEM;
55
56 if (skas_needs_stub) {
57 stack = get_zeroed_page(GFP_KERNEL);
58 if (stack == 0)
59 goto out;
60 }
61
62 to_mm->id.stack = stack;
63 if (current->mm != NULL && current->mm != &init_mm)
64 from_mm = ¤t->mm->context;
65
66 if (proc_mm) {
67 ret = new_mm(stack);
68 if (ret < 0) {
69 printk(KERN_ERR "init_new_context_skas - "
70 "new_mm failed, errno = %d\n", ret);
71 goto out_free;
72 }
73 to_mm->id.u.mm_fd = ret;
74 }
75 else {
76 if (from_mm)
77 to_mm->id.u.pid = copy_context_skas0(stack,
78 from_mm->id.u.pid);
79 else to_mm->id.u.pid = start_userspace(stack);
80
81 if (to_mm->id.u.pid < 0) {
82 ret = to_mm->id.u.pid;
83 goto out_free;
84 }
85 }
86
87 ret = init_new_ldt(to_mm, from_mm);
88 if (ret < 0) {
89 printk(KERN_ERR "init_new_context_skas - init_ldt"
90 " failed, errno = %d\n", ret);
91 goto out_free;
92 }
93
94 to_mm->stub_pages = NULL;
95
96 return 0;
97
98 out_free:
99 if (to_mm->id.stack != 0)
100 free_page(to_mm->id.stack);
101 out:
102 return ret;
103 }
104
arch_dup_mmap(struct mm_struct * oldmm,struct mm_struct * mm)105 void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
106 {
107 struct page **pages;
108 int err, ret;
109
110 if (!skas_needs_stub)
111 return;
112
113 ret = init_stub_pte(mm, STUB_CODE,
114 (unsigned long) &__syscall_stub_start);
115 if (ret)
116 goto out;
117
118 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
119 if (ret)
120 goto out;
121
122 pages = kmalloc(2 * sizeof(struct page *), GFP_KERNEL);
123 if (pages == NULL) {
124 printk(KERN_ERR "arch_dup_mmap failed to allocate 2 page "
125 "pointers\n");
126 goto out;
127 }
128
129 pages[0] = virt_to_page(&__syscall_stub_start);
130 pages[1] = virt_to_page(mm->context.id.stack);
131 mm->context.stub_pages = pages;
132
133 /* dup_mmap already holds mmap_sem */
134 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
135 VM_READ | VM_MAYREAD | VM_EXEC |
136 VM_MAYEXEC | VM_DONTCOPY, pages);
137 if (err) {
138 printk(KERN_ERR "install_special_mapping returned %d\n", err);
139 goto out_free;
140 }
141 return;
142
143 out_free:
144 kfree(pages);
145 out:
146 force_sigsegv(SIGSEGV, current);
147 }
148
arch_exit_mmap(struct mm_struct * mm)149 void arch_exit_mmap(struct mm_struct *mm)
150 {
151 pte_t *pte;
152
153 if (mm->context.stub_pages != NULL)
154 kfree(mm->context.stub_pages);
155 pte = virt_to_pte(mm, STUB_CODE);
156 if (pte != NULL)
157 pte_clear(mm, STUB_CODE, pte);
158
159 pte = virt_to_pte(mm, STUB_DATA);
160 if (pte == NULL)
161 return;
162
163 pte_clear(mm, STUB_DATA, pte);
164 }
165
destroy_context(struct mm_struct * mm)166 void destroy_context(struct mm_struct *mm)
167 {
168 struct mm_context *mmu = &mm->context;
169
170 if (proc_mm)
171 os_close_file(mmu->id.u.mm_fd);
172 else {
173 /*
174 * If init_new_context wasn't called, this will be
175 * zero, resulting in a kill(0), which will result in the
176 * whole UML suddenly dying. Also, cover negative and
177 * 1 cases, since they shouldn't happen either.
178 */
179 if (mmu->id.u.pid < 2) {
180 printk(KERN_ERR "corrupt mm_context - pid = %d\n",
181 mmu->id.u.pid);
182 return;
183 }
184 os_kill_ptraced_process(mmu->id.u.pid, 1);
185 }
186
187 if (skas_needs_stub)
188 free_page(mmu->id.stack);
189
190 free_ldt(mmu);
191 }
192