]>
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> | |
70ffdb93 | 13 | #include <linux/uaccess.h> |
1da177e4 LT |
14 | |
15 | #include <asm/setup.h> | |
16 | #include <asm/traps.h> | |
1da177e4 LT |
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; | |
8e398f63 GU |
28 | pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, |
29 | siginfo.si_signo, siginfo.si_code); | |
1da177e4 LT |
30 | |
31 | if (user_mode(regs)) { | |
32 | force_sig_info(siginfo.si_signo, | |
33 | &siginfo, current); | |
34 | } else { | |
dcdf3a29 | 35 | if (handle_kernel_fault(regs)) |
1da177e4 | 36 | return -1; |
1da177e4 LT |
37 | |
38 | //if (siginfo.si_signo == SIGBUS) | |
39 | // force_sig_info(siginfo.si_signo, | |
40 | // &siginfo, current); | |
41 | ||
42 | /* | |
43 | * Oops. The kernel tried to access some bad page. We'll have to | |
44 | * terminate things with extreme prejudice. | |
45 | */ | |
46 | if ((unsigned long)siginfo.si_addr < PAGE_SIZE) | |
8e398f63 | 47 | pr_alert("Unable to handle kernel NULL pointer dereference"); |
1da177e4 | 48 | else |
8e398f63 GU |
49 | pr_alert("Unable to handle kernel access"); |
50 | pr_cont(" at virtual address %p\n", siginfo.si_addr); | |
1da177e4 LT |
51 | die_if_kernel("Oops", regs, 0 /*error_code*/); |
52 | do_exit(SIGKILL); | |
53 | } | |
54 | ||
55 | return 1; | |
56 | } | |
57 | ||
58 | /* | |
59 | * This routine handles page faults. It determines the problem, and | |
60 | * then passes it off to one of the appropriate routines. | |
61 | * | |
62 | * error_code: | |
63 | * bit 0 == 0 means no page found, 1 means protection fault | |
64 | * bit 1 == 0 means read, 1 means write | |
65 | * | |
66 | * If this routine detects a bad access, it returns 1, otherwise it | |
67 | * returns 0. | |
68 | */ | |
69 | int do_page_fault(struct pt_regs *regs, unsigned long address, | |
70 | unsigned long error_code) | |
71 | { | |
72 | struct mm_struct *mm = current->mm; | |
73 | struct vm_area_struct * vma; | |
b637a6b1 KC |
74 | int fault; |
75 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; | |
1da177e4 | 76 | |
8e398f63 | 77 | pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", |
4e25c0e9 | 78 | regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL); |
1da177e4 LT |
79 | |
80 | /* | |
81 | * If we're in an interrupt or have no user | |
82 | * context, we must not take the fault.. | |
83 | */ | |
70ffdb93 | 84 | if (faulthandler_disabled() || !mm) |
1da177e4 LT |
85 | goto no_context; |
86 | ||
759496ba JW |
87 | if (user_mode(regs)) |
88 | flags |= FAULT_FLAG_USER; | |
b637a6b1 | 89 | retry: |
1da177e4 LT |
90 | down_read(&mm->mmap_sem); |
91 | ||
92 | vma = find_vma(mm, address); | |
93 | if (!vma) | |
94 | goto map_err; | |
95 | if (vma->vm_flags & VM_IO) | |
96 | goto acc_err; | |
97 | if (vma->vm_start <= address) | |
98 | goto good_area; | |
99 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
100 | goto map_err; | |
101 | if (user_mode(regs)) { | |
102 | /* Accessing the stack below usp is always a bug. The | |
103 | "+ 256" is there due to some instructions doing | |
104 | pre-decrement on the stack and that doesn't show up | |
105 | until later. */ | |
106 | if (address + 256 < rdusp()) | |
107 | goto map_err; | |
108 | } | |
109 | if (expand_stack(vma, address)) | |
110 | goto map_err; | |
111 | ||
112 | /* | |
113 | * Ok, we have a good vm_area for this memory access, so | |
114 | * we can handle it.. | |
115 | */ | |
116 | good_area: | |
8e398f63 | 117 | pr_debug("do_page_fault: good_area\n"); |
1da177e4 LT |
118 | switch (error_code & 3) { |
119 | default: /* 3: write, present */ | |
120 | /* fall through */ | |
121 | case 2: /* write, not present */ | |
122 | if (!(vma->vm_flags & VM_WRITE)) | |
123 | goto acc_err; | |
b637a6b1 | 124 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
125 | break; |
126 | case 1: /* read, present */ | |
127 | goto acc_err; | |
128 | case 0: /* read, not present */ | |
df67b3da | 129 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
1da177e4 LT |
130 | goto acc_err; |
131 | } | |
132 | ||
133 | /* | |
134 | * If for any reason at all we couldn't handle the fault, | |
135 | * make sure we exit gracefully rather than endlessly redo | |
136 | * the fault. | |
137 | */ | |
138 | ||
b637a6b1 | 139 | fault = handle_mm_fault(mm, vma, address, flags); |
8e398f63 | 140 | pr_debug("handle_mm_fault returns %d\n", fault); |
b637a6b1 KC |
141 | |
142 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
143 | return 0; | |
144 | ||
83c54070 NP |
145 | if (unlikely(fault & VM_FAULT_ERROR)) { |
146 | if (fault & VM_FAULT_OOM) | |
147 | goto out_of_memory; | |
33692f27 LT |
148 | else if (fault & VM_FAULT_SIGSEGV) |
149 | goto map_err; | |
83c54070 NP |
150 | else if (fault & VM_FAULT_SIGBUS) |
151 | goto bus_err; | |
152 | BUG(); | |
1da177e4 | 153 | } |
b637a6b1 KC |
154 | |
155 | /* | |
156 | * Major/minor page fault accounting is only done on the | |
157 | * initial attempt. If we go through a retry, it is extremely | |
158 | * likely that the page will be found in page cache at that point. | |
159 | */ | |
160 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
161 | if (fault & VM_FAULT_MAJOR) | |
162 | current->maj_flt++; | |
163 | else | |
164 | current->min_flt++; | |
165 | if (fault & VM_FAULT_RETRY) { | |
166 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk | |
167 | * of starvation. */ | |
168 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 169 | flags |= FAULT_FLAG_TRIED; |
b637a6b1 KC |
170 | |
171 | /* | |
172 | * No need to up_read(&mm->mmap_sem) as we would | |
173 | * have already released it in __lock_page_or_retry | |
174 | * in mm/filemap.c. | |
175 | */ | |
176 | ||
177 | goto retry; | |
178 | } | |
179 | } | |
1da177e4 LT |
180 | |
181 | up_read(&mm->mmap_sem); | |
182 | return 0; | |
183 | ||
184 | /* | |
185 | * We ran out of memory, or some other thing happened to us that made | |
186 | * us unable to handle the page fault gracefully. | |
187 | */ | |
188 | out_of_memory: | |
189 | up_read(&mm->mmap_sem); | |
adbf6e69 NP |
190 | if (!user_mode(regs)) |
191 | goto no_context; | |
192 | pagefault_out_of_memory(); | |
193 | return 0; | |
1da177e4 LT |
194 | |
195 | no_context: | |
196 | current->thread.signo = SIGBUS; | |
197 | current->thread.faddr = address; | |
198 | return send_fault_sig(regs); | |
199 | ||
200 | bus_err: | |
201 | current->thread.signo = SIGBUS; | |
202 | current->thread.code = BUS_ADRERR; | |
203 | current->thread.faddr = address; | |
204 | goto send_sig; | |
205 | ||
206 | map_err: | |
207 | current->thread.signo = SIGSEGV; | |
208 | current->thread.code = SEGV_MAPERR; | |
209 | current->thread.faddr = address; | |
210 | goto send_sig; | |
211 | ||
212 | acc_err: | |
213 | current->thread.signo = SIGSEGV; | |
214 | current->thread.code = SEGV_ACCERR; | |
215 | current->thread.faddr = address; | |
216 | ||
217 | send_sig: | |
218 | up_read(&mm->mmap_sem); | |
219 | return send_fault_sig(regs); | |
220 | } |