Commit | Line | Data |
---|---|---|
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> | |
1da177e4 LT |
16 | #include <asm/uaccess.h> |
17 | #include <asm/pgalloc.h> | |
18 | ||
19 | extern void die_if_kernel(char *, struct pt_regs *, long); | |
1da177e4 LT |
20 | |
21 | int send_fault_sig(struct pt_regs *regs) | |
22 | { | |
23 | siginfo_t siginfo = { 0, 0, 0, }; | |
24 | ||
25 | siginfo.si_signo = current->thread.signo; | |
26 | siginfo.si_code = current->thread.code; | |
27 | siginfo.si_addr = (void *)current->thread.faddr; | |
28 | #ifdef DEBUG | |
29 | printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code); | |
30 | #endif | |
31 | ||
32 | if (user_mode(regs)) { | |
33 | force_sig_info(siginfo.si_signo, | |
34 | &siginfo, current); | |
35 | } else { | |
dcdf3a29 | 36 | if (handle_kernel_fault(regs)) |
1da177e4 | 37 | return -1; |
1da177e4 LT |
38 | |
39 | //if (siginfo.si_signo == SIGBUS) | |
40 | // force_sig_info(siginfo.si_signo, | |
41 | // &siginfo, current); | |
42 | ||
43 | /* | |
44 | * Oops. The kernel tried to access some bad page. We'll have to | |
45 | * terminate things with extreme prejudice. | |
46 | */ | |
47 | if ((unsigned long)siginfo.si_addr < PAGE_SIZE) | |
48 | printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); | |
49 | else | |
50 | printk(KERN_ALERT "Unable to handle kernel access"); | |
51 | printk(" at virtual address %p\n", siginfo.si_addr); | |
52 | die_if_kernel("Oops", regs, 0 /*error_code*/); | |
53 | do_exit(SIGKILL); | |
54 | } | |
55 | ||
56 | return 1; | |
57 | } | |
58 | ||
59 | /* | |
60 | * This routine handles page faults. It determines the problem, and | |
61 | * then passes it off to one of the appropriate routines. | |
62 | * | |
63 | * error_code: | |
64 | * bit 0 == 0 means no page found, 1 means protection fault | |
65 | * bit 1 == 0 means read, 1 means write | |
66 | * | |
67 | * If this routine detects a bad access, it returns 1, otherwise it | |
68 | * returns 0. | |
69 | */ | |
70 | int do_page_fault(struct pt_regs *regs, unsigned long address, | |
71 | unsigned long error_code) | |
72 | { | |
73 | struct mm_struct *mm = current->mm; | |
74 | struct vm_area_struct * vma; | |
b637a6b1 KC |
75 | int fault; |
76 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; | |
1da177e4 LT |
77 | |
78 | #ifdef DEBUG | |
79 | printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", | |
80 | regs->sr, regs->pc, address, error_code, | |
81 | current->mm->pgd); | |
82 | #endif | |
83 | ||
84 | /* | |
85 | * If we're in an interrupt or have no user | |
86 | * context, we must not take the fault.. | |
87 | */ | |
6edaf68a | 88 | if (in_atomic() || !mm) |
1da177e4 LT |
89 | goto no_context; |
90 | ||
b637a6b1 | 91 | retry: |
1da177e4 LT |
92 | down_read(&mm->mmap_sem); |
93 | ||
94 | vma = find_vma(mm, address); | |
95 | if (!vma) | |
96 | goto map_err; | |
97 | if (vma->vm_flags & VM_IO) | |
98 | goto acc_err; | |
99 | if (vma->vm_start <= address) | |
100 | goto good_area; | |
101 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
102 | goto map_err; | |
103 | if (user_mode(regs)) { | |
104 | /* Accessing the stack below usp is always a bug. The | |
105 | "+ 256" is there due to some instructions doing | |
106 | pre-decrement on the stack and that doesn't show up | |
107 | until later. */ | |
108 | if (address + 256 < rdusp()) | |
109 | goto map_err; | |
110 | } | |
111 | if (expand_stack(vma, address)) | |
112 | goto map_err; | |
113 | ||
114 | /* | |
115 | * Ok, we have a good vm_area for this memory access, so | |
116 | * we can handle it.. | |
117 | */ | |
118 | good_area: | |
119 | #ifdef DEBUG | |
120 | printk("do_page_fault: good_area\n"); | |
121 | #endif | |
1da177e4 LT |
122 | switch (error_code & 3) { |
123 | default: /* 3: write, present */ | |
124 | /* fall through */ | |
125 | case 2: /* write, not present */ | |
126 | if (!(vma->vm_flags & VM_WRITE)) | |
127 | goto acc_err; | |
b637a6b1 | 128 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
129 | break; |
130 | case 1: /* read, present */ | |
131 | goto acc_err; | |
132 | case 0: /* read, not present */ | |
df67b3da | 133 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
1da177e4 LT |
134 | goto acc_err; |
135 | } | |
136 | ||
137 | /* | |
138 | * If for any reason at all we couldn't handle the fault, | |
139 | * make sure we exit gracefully rather than endlessly redo | |
140 | * the fault. | |
141 | */ | |
142 | ||
b637a6b1 | 143 | fault = handle_mm_fault(mm, vma, address, flags); |
1da177e4 LT |
144 | #ifdef DEBUG |
145 | printk("handle_mm_fault returns %d\n",fault); | |
146 | #endif | |
b637a6b1 KC |
147 | |
148 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
149 | return 0; | |
150 | ||
83c54070 NP |
151 | if (unlikely(fault & VM_FAULT_ERROR)) { |
152 | if (fault & VM_FAULT_OOM) | |
153 | goto out_of_memory; | |
154 | else if (fault & VM_FAULT_SIGBUS) | |
155 | goto bus_err; | |
156 | BUG(); | |
1da177e4 | 157 | } |
b637a6b1 KC |
158 | |
159 | /* | |
160 | * Major/minor page fault accounting is only done on the | |
161 | * initial attempt. If we go through a retry, it is extremely | |
162 | * likely that the page will be found in page cache at that point. | |
163 | */ | |
164 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
165 | if (fault & VM_FAULT_MAJOR) | |
166 | current->maj_flt++; | |
167 | else | |
168 | current->min_flt++; | |
169 | if (fault & VM_FAULT_RETRY) { | |
170 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk | |
171 | * of starvation. */ | |
172 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 173 | flags |= FAULT_FLAG_TRIED; |
b637a6b1 KC |
174 | |
175 | /* | |
176 | * No need to up_read(&mm->mmap_sem) as we would | |
177 | * have already released it in __lock_page_or_retry | |
178 | * in mm/filemap.c. | |
179 | */ | |
180 | ||
181 | goto retry; | |
182 | } | |
183 | } | |
1da177e4 LT |
184 | |
185 | up_read(&mm->mmap_sem); | |
186 | return 0; | |
187 | ||
188 | /* | |
189 | * We ran out of memory, or some other thing happened to us that made | |
190 | * us unable to handle the page fault gracefully. | |
191 | */ | |
192 | out_of_memory: | |
193 | up_read(&mm->mmap_sem); | |
adbf6e69 NP |
194 | if (!user_mode(regs)) |
195 | goto no_context; | |
196 | pagefault_out_of_memory(); | |
197 | return 0; | |
1da177e4 LT |
198 | |
199 | no_context: | |
200 | current->thread.signo = SIGBUS; | |
201 | current->thread.faddr = address; | |
202 | return send_fault_sig(regs); | |
203 | ||
204 | bus_err: | |
205 | current->thread.signo = SIGBUS; | |
206 | current->thread.code = BUS_ADRERR; | |
207 | current->thread.faddr = address; | |
208 | goto send_sig; | |
209 | ||
210 | map_err: | |
211 | current->thread.signo = SIGSEGV; | |
212 | current->thread.code = SEGV_MAPERR; | |
213 | current->thread.faddr = address; | |
214 | goto send_sig; | |
215 | ||
216 | acc_err: | |
217 | current->thread.signo = SIGSEGV; | |
218 | current->thread.code = SEGV_ACCERR; | |
219 | current->thread.faddr = address; | |
220 | ||
221 | send_sig: | |
222 | up_read(&mm->mmap_sem); | |
223 | return send_fault_sig(regs); | |
224 | } |