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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/arch/m68k/mm/fault.c | |
4 | * | |
5 | * Copyright (C) 1995 Hamish Macdonald | |
6 | */ | |
7 | ||
8 | #include <linux/mman.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/ptrace.h> | |
12 | #include <linux/interrupt.h> | |
13 | #include <linux/module.h> | |
70ffdb93 | 14 | #include <linux/uaccess.h> |
1da177e4 LT |
15 | |
16 | #include <asm/setup.h> | |
17 | #include <asm/traps.h> | |
1da177e4 LT |
18 | #include <asm/pgalloc.h> |
19 | ||
20 | extern void die_if_kernel(char *, struct pt_regs *, long); | |
1da177e4 LT |
21 | |
22 | int send_fault_sig(struct pt_regs *regs) | |
23 | { | |
3c67075d EB |
24 | int signo, si_code; |
25 | void __user *addr; | |
1da177e4 | 26 | |
3c67075d EB |
27 | signo = current->thread.signo; |
28 | si_code = current->thread.code; | |
29 | addr = (void __user *)current->thread.faddr; | |
30 | pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code); | |
1da177e4 LT |
31 | |
32 | if (user_mode(regs)) { | |
2e1661d2 | 33 | force_sig_fault(signo, si_code, addr); |
1da177e4 | 34 | } else { |
68acfdcb | 35 | if (fixup_exception(regs)) |
1da177e4 | 36 | return -1; |
1da177e4 | 37 | |
3c67075d | 38 | //if (signo == SIGBUS) |
2e1661d2 | 39 | // force_sig_fault(si_signo, si_code, addr); |
1da177e4 LT |
40 | |
41 | /* | |
42 | * Oops. The kernel tried to access some bad page. We'll have to | |
43 | * terminate things with extreme prejudice. | |
44 | */ | |
3c67075d | 45 | if ((unsigned long)addr < PAGE_SIZE) |
8e398f63 | 46 | pr_alert("Unable to handle kernel NULL pointer dereference"); |
1da177e4 | 47 | else |
8e398f63 | 48 | pr_alert("Unable to handle kernel access"); |
3c67075d | 49 | pr_cont(" at virtual address %p\n", addr); |
1da177e4 LT |
50 | die_if_kernel("Oops", regs, 0 /*error_code*/); |
51 | do_exit(SIGKILL); | |
52 | } | |
53 | ||
54 | return 1; | |
55 | } | |
56 | ||
57 | /* | |
58 | * This routine handles page faults. It determines the problem, and | |
59 | * then passes it off to one of the appropriate routines. | |
60 | * | |
61 | * error_code: | |
62 | * bit 0 == 0 means no page found, 1 means protection fault | |
63 | * bit 1 == 0 means read, 1 means write | |
64 | * | |
65 | * If this routine detects a bad access, it returns 1, otherwise it | |
66 | * returns 0. | |
67 | */ | |
68 | int do_page_fault(struct pt_regs *regs, unsigned long address, | |
69 | unsigned long error_code) | |
70 | { | |
71 | struct mm_struct *mm = current->mm; | |
72 | struct vm_area_struct * vma; | |
50a7ca3c | 73 | vm_fault_t fault; |
b637a6b1 | 74 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
1da177e4 | 75 | |
8e398f63 | 76 | pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", |
4e25c0e9 | 77 | regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL); |
1da177e4 LT |
78 | |
79 | /* | |
80 | * If we're in an interrupt or have no user | |
81 | * context, we must not take the fault.. | |
82 | */ | |
70ffdb93 | 83 | if (faulthandler_disabled() || !mm) |
1da177e4 LT |
84 | goto no_context; |
85 | ||
759496ba JW |
86 | if (user_mode(regs)) |
87 | flags |= FAULT_FLAG_USER; | |
b637a6b1 | 88 | retry: |
1da177e4 LT |
89 | down_read(&mm->mmap_sem); |
90 | ||
91 | vma = find_vma(mm, address); | |
92 | if (!vma) | |
93 | goto map_err; | |
94 | if (vma->vm_flags & VM_IO) | |
95 | goto acc_err; | |
96 | if (vma->vm_start <= address) | |
97 | goto good_area; | |
98 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
99 | goto map_err; | |
100 | if (user_mode(regs)) { | |
101 | /* Accessing the stack below usp is always a bug. The | |
102 | "+ 256" is there due to some instructions doing | |
103 | pre-decrement on the stack and that doesn't show up | |
104 | until later. */ | |
105 | if (address + 256 < rdusp()) | |
106 | goto map_err; | |
107 | } | |
108 | if (expand_stack(vma, address)) | |
109 | goto map_err; | |
110 | ||
111 | /* | |
112 | * Ok, we have a good vm_area for this memory access, so | |
113 | * we can handle it.. | |
114 | */ | |
115 | good_area: | |
8e398f63 | 116 | pr_debug("do_page_fault: good_area\n"); |
1da177e4 LT |
117 | switch (error_code & 3) { |
118 | default: /* 3: write, present */ | |
119 | /* fall through */ | |
120 | case 2: /* write, not present */ | |
121 | if (!(vma->vm_flags & VM_WRITE)) | |
122 | goto acc_err; | |
b637a6b1 | 123 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
124 | break; |
125 | case 1: /* read, present */ | |
126 | goto acc_err; | |
127 | case 0: /* read, not present */ | |
df67b3da | 128 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
1da177e4 LT |
129 | goto acc_err; |
130 | } | |
131 | ||
132 | /* | |
133 | * If for any reason at all we couldn't handle the fault, | |
134 | * make sure we exit gracefully rather than endlessly redo | |
135 | * the fault. | |
136 | */ | |
137 | ||
dcddffd4 | 138 | fault = handle_mm_fault(vma, address, flags); |
50a7ca3c | 139 | pr_debug("handle_mm_fault returns %x\n", fault); |
b637a6b1 KC |
140 | |
141 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
142 | return 0; | |
143 | ||
83c54070 NP |
144 | if (unlikely(fault & VM_FAULT_ERROR)) { |
145 | if (fault & VM_FAULT_OOM) | |
146 | goto out_of_memory; | |
33692f27 LT |
147 | else if (fault & VM_FAULT_SIGSEGV) |
148 | goto map_err; | |
83c54070 NP |
149 | else if (fault & VM_FAULT_SIGBUS) |
150 | goto bus_err; | |
151 | BUG(); | |
1da177e4 | 152 | } |
b637a6b1 KC |
153 | |
154 | /* | |
155 | * Major/minor page fault accounting is only done on the | |
156 | * initial attempt. If we go through a retry, it is extremely | |
157 | * likely that the page will be found in page cache at that point. | |
158 | */ | |
159 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
160 | if (fault & VM_FAULT_MAJOR) | |
161 | current->maj_flt++; | |
162 | else | |
163 | current->min_flt++; | |
164 | if (fault & VM_FAULT_RETRY) { | |
165 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk | |
166 | * of starvation. */ | |
167 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 168 | flags |= FAULT_FLAG_TRIED; |
b637a6b1 KC |
169 | |
170 | /* | |
171 | * No need to up_read(&mm->mmap_sem) as we would | |
172 | * have already released it in __lock_page_or_retry | |
173 | * in mm/filemap.c. | |
174 | */ | |
175 | ||
176 | goto retry; | |
177 | } | |
178 | } | |
1da177e4 LT |
179 | |
180 | up_read(&mm->mmap_sem); | |
181 | return 0; | |
182 | ||
183 | /* | |
184 | * We ran out of memory, or some other thing happened to us that made | |
185 | * us unable to handle the page fault gracefully. | |
186 | */ | |
187 | out_of_memory: | |
188 | up_read(&mm->mmap_sem); | |
adbf6e69 NP |
189 | if (!user_mode(regs)) |
190 | goto no_context; | |
191 | pagefault_out_of_memory(); | |
192 | return 0; | |
1da177e4 LT |
193 | |
194 | no_context: | |
195 | current->thread.signo = SIGBUS; | |
196 | current->thread.faddr = address; | |
197 | return send_fault_sig(regs); | |
198 | ||
199 | bus_err: | |
200 | current->thread.signo = SIGBUS; | |
201 | current->thread.code = BUS_ADRERR; | |
202 | current->thread.faddr = address; | |
203 | goto send_sig; | |
204 | ||
205 | map_err: | |
206 | current->thread.signo = SIGSEGV; | |
207 | current->thread.code = SEGV_MAPERR; | |
208 | current->thread.faddr = address; | |
209 | goto send_sig; | |
210 | ||
211 | acc_err: | |
212 | current->thread.signo = SIGSEGV; | |
213 | current->thread.code = SEGV_ACCERR; | |
214 | current->thread.faddr = address; | |
215 | ||
216 | send_sig: | |
217 | up_read(&mm->mmap_sem); | |
218 | return send_fault_sig(regs); | |
219 | } |