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1da177e4 LT |
1 | /* |
2 | * linux/arch/m68k/mm/fault.c | |
3 | * | |
4 | * Copyright (C) 1995 Hamish Macdonald | |
5 | */ | |
6 | ||
7 | #include <linux/mman.h> | |
8 | #include <linux/mm.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/ptrace.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/module.h> | |
13 | ||
14 | #include <asm/setup.h> | |
15 | #include <asm/traps.h> | |
16 | #include <asm/system.h> | |
17 | #include <asm/uaccess.h> | |
18 | #include <asm/pgalloc.h> | |
19 | ||
20 | extern void die_if_kernel(char *, struct pt_regs *, long); | |
21 | extern const int frame_extra_sizes[]; /* in m68k/kernel/signal.c */ | |
22 | ||
23 | int send_fault_sig(struct pt_regs *regs) | |
24 | { | |
25 | siginfo_t siginfo = { 0, 0, 0, }; | |
26 | ||
27 | siginfo.si_signo = current->thread.signo; | |
28 | siginfo.si_code = current->thread.code; | |
29 | siginfo.si_addr = (void *)current->thread.faddr; | |
30 | #ifdef DEBUG | |
31 | printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code); | |
32 | #endif | |
33 | ||
34 | if (user_mode(regs)) { | |
35 | force_sig_info(siginfo.si_signo, | |
36 | &siginfo, current); | |
37 | } else { | |
38 | const struct exception_table_entry *fixup; | |
39 | ||
40 | /* Are we prepared to handle this kernel fault? */ | |
41 | if ((fixup = search_exception_tables(regs->pc))) { | |
42 | struct pt_regs *tregs; | |
43 | /* Create a new four word stack frame, discarding the old | |
44 | one. */ | |
45 | regs->stkadj = frame_extra_sizes[regs->format]; | |
46 | tregs = (struct pt_regs *)((ulong)regs + regs->stkadj); | |
47 | tregs->vector = regs->vector; | |
48 | tregs->format = 0; | |
49 | tregs->pc = fixup->fixup; | |
50 | tregs->sr = regs->sr; | |
51 | return -1; | |
52 | } | |
53 | ||
54 | //if (siginfo.si_signo == SIGBUS) | |
55 | // force_sig_info(siginfo.si_signo, | |
56 | // &siginfo, current); | |
57 | ||
58 | /* | |
59 | * Oops. The kernel tried to access some bad page. We'll have to | |
60 | * terminate things with extreme prejudice. | |
61 | */ | |
62 | if ((unsigned long)siginfo.si_addr < PAGE_SIZE) | |
63 | printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); | |
64 | else | |
65 | printk(KERN_ALERT "Unable to handle kernel access"); | |
66 | printk(" at virtual address %p\n", siginfo.si_addr); | |
67 | die_if_kernel("Oops", regs, 0 /*error_code*/); | |
68 | do_exit(SIGKILL); | |
69 | } | |
70 | ||
71 | return 1; | |
72 | } | |
73 | ||
74 | /* | |
75 | * This routine handles page faults. It determines the problem, and | |
76 | * then passes it off to one of the appropriate routines. | |
77 | * | |
78 | * error_code: | |
79 | * bit 0 == 0 means no page found, 1 means protection fault | |
80 | * bit 1 == 0 means read, 1 means write | |
81 | * | |
82 | * If this routine detects a bad access, it returns 1, otherwise it | |
83 | * returns 0. | |
84 | */ | |
85 | int do_page_fault(struct pt_regs *regs, unsigned long address, | |
86 | unsigned long error_code) | |
87 | { | |
88 | struct mm_struct *mm = current->mm; | |
89 | struct vm_area_struct * vma; | |
90 | int write, fault; | |
91 | ||
92 | #ifdef DEBUG | |
93 | printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", | |
94 | regs->sr, regs->pc, address, error_code, | |
95 | current->mm->pgd); | |
96 | #endif | |
97 | ||
98 | /* | |
99 | * If we're in an interrupt or have no user | |
100 | * context, we must not take the fault.. | |
101 | */ | |
6edaf68a | 102 | if (in_atomic() || !mm) |
1da177e4 LT |
103 | goto no_context; |
104 | ||
105 | down_read(&mm->mmap_sem); | |
106 | ||
107 | vma = find_vma(mm, address); | |
108 | if (!vma) | |
109 | goto map_err; | |
110 | if (vma->vm_flags & VM_IO) | |
111 | goto acc_err; | |
112 | if (vma->vm_start <= address) | |
113 | goto good_area; | |
114 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
115 | goto map_err; | |
116 | if (user_mode(regs)) { | |
117 | /* Accessing the stack below usp is always a bug. The | |
118 | "+ 256" is there due to some instructions doing | |
119 | pre-decrement on the stack and that doesn't show up | |
120 | until later. */ | |
121 | if (address + 256 < rdusp()) | |
122 | goto map_err; | |
123 | } | |
124 | if (expand_stack(vma, address)) | |
125 | goto map_err; | |
126 | ||
127 | /* | |
128 | * Ok, we have a good vm_area for this memory access, so | |
129 | * we can handle it.. | |
130 | */ | |
131 | good_area: | |
132 | #ifdef DEBUG | |
133 | printk("do_page_fault: good_area\n"); | |
134 | #endif | |
135 | write = 0; | |
136 | switch (error_code & 3) { | |
137 | default: /* 3: write, present */ | |
138 | /* fall through */ | |
139 | case 2: /* write, not present */ | |
140 | if (!(vma->vm_flags & VM_WRITE)) | |
141 | goto acc_err; | |
142 | write++; | |
143 | break; | |
144 | case 1: /* read, present */ | |
145 | goto acc_err; | |
146 | case 0: /* read, not present */ | |
df67b3da | 147 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
1da177e4 LT |
148 | goto acc_err; |
149 | } | |
150 | ||
151 | /* | |
152 | * If for any reason at all we couldn't handle the fault, | |
153 | * make sure we exit gracefully rather than endlessly redo | |
154 | * the fault. | |
155 | */ | |
156 | ||
157 | survive: | |
158 | fault = handle_mm_fault(mm, vma, address, write); | |
159 | #ifdef DEBUG | |
160 | printk("handle_mm_fault returns %d\n",fault); | |
161 | #endif | |
83c54070 NP |
162 | if (unlikely(fault & VM_FAULT_ERROR)) { |
163 | if (fault & VM_FAULT_OOM) | |
164 | goto out_of_memory; | |
165 | else if (fault & VM_FAULT_SIGBUS) | |
166 | goto bus_err; | |
167 | BUG(); | |
1da177e4 | 168 | } |
83c54070 NP |
169 | if (fault & VM_FAULT_MAJOR) |
170 | current->maj_flt++; | |
171 | else | |
172 | current->min_flt++; | |
1da177e4 LT |
173 | |
174 | up_read(&mm->mmap_sem); | |
175 | return 0; | |
176 | ||
177 | /* | |
178 | * We ran out of memory, or some other thing happened to us that made | |
179 | * us unable to handle the page fault gracefully. | |
180 | */ | |
181 | out_of_memory: | |
182 | up_read(&mm->mmap_sem); | |
b460cbc5 | 183 | if (is_global_init(current)) { |
1da177e4 LT |
184 | yield(); |
185 | down_read(&mm->mmap_sem); | |
186 | goto survive; | |
187 | } | |
188 | ||
189 | printk("VM: killing process %s\n", current->comm); | |
190 | if (user_mode(regs)) | |
dcca2bde | 191 | do_group_exit(SIGKILL); |
1da177e4 LT |
192 | |
193 | no_context: | |
194 | current->thread.signo = SIGBUS; | |
195 | current->thread.faddr = address; | |
196 | return send_fault_sig(regs); | |
197 | ||
198 | bus_err: | |
199 | current->thread.signo = SIGBUS; | |
200 | current->thread.code = BUS_ADRERR; | |
201 | current->thread.faddr = address; | |
202 | goto send_sig; | |
203 | ||
204 | map_err: | |
205 | current->thread.signo = SIGSEGV; | |
206 | current->thread.code = SEGV_MAPERR; | |
207 | current->thread.faddr = address; | |
208 | goto send_sig; | |
209 | ||
210 | acc_err: | |
211 | current->thread.signo = SIGSEGV; | |
212 | current->thread.code = SEGV_ACCERR; | |
213 | current->thread.faddr = address; | |
214 | ||
215 | send_sig: | |
216 | up_read(&mm->mmap_sem); | |
217 | return send_fault_sig(regs); | |
218 | } |