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1da177e4 LT |
1 | /* |
2 | * This file is subject to the terms and conditions of the GNU General Public | |
3 | * License. See the file "COPYING" in the main directory of this archive | |
4 | * for more details. | |
5 | * | |
6 | * Copyright (C) 1995 - 2000 by Ralf Baechle | |
7 | */ | |
8 | #include <linux/signal.h> | |
9 | #include <linux/sched.h> | |
10 | #include <linux/interrupt.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/string.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/ptrace.h> | |
16 | #include <linux/mman.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/smp.h> | |
1da177e4 LT |
19 | #include <linux/vt_kern.h> /* For unblank_screen() */ |
20 | #include <linux/module.h> | |
21 | ||
22 | #include <asm/branch.h> | |
23 | #include <asm/mmu_context.h> | |
24 | #include <asm/system.h> | |
25 | #include <asm/uaccess.h> | |
26 | #include <asm/ptrace.h> | |
16033d61 | 27 | #include <asm/highmem.h> /* For VMALLOC_END */ |
1da177e4 LT |
28 | |
29 | /* | |
30 | * This routine handles page faults. It determines the address, | |
31 | * and the problem, and then passes it off to one of the appropriate | |
32 | * routines. | |
33 | */ | |
34 | asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, | |
35 | unsigned long address) | |
36 | { | |
37 | struct vm_area_struct * vma = NULL; | |
38 | struct task_struct *tsk = current; | |
39 | struct mm_struct *mm = tsk->mm; | |
40 | const int field = sizeof(unsigned long) * 2; | |
41 | siginfo_t info; | |
83c54070 | 42 | int fault; |
1da177e4 LT |
43 | |
44 | #if 0 | |
d6f70360 | 45 | printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), |
1da177e4 LT |
46 | current->comm, current->pid, field, address, write, |
47 | field, regs->cp0_epc); | |
48 | #endif | |
49 | ||
50 | info.si_code = SEGV_MAPERR; | |
51 | ||
52 | /* | |
53 | * We fault-in kernel-space virtual memory on-demand. The | |
54 | * 'reference' page table is init_mm.pgd. | |
55 | * | |
56 | * NOTE! We MUST NOT take any locks for this case. We may | |
57 | * be in an interrupt or a critical region, and should | |
58 | * only copy the information from the master page table, | |
59 | * nothing more. | |
60 | */ | |
16033d61 | 61 | if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) |
1da177e4 | 62 | goto vmalloc_fault; |
656be92f AN |
63 | #ifdef MODULE_START |
64 | if (unlikely(address >= MODULE_START && address < MODULE_END)) | |
65 | goto vmalloc_fault; | |
66 | #endif | |
1da177e4 LT |
67 | |
68 | /* | |
69 | * If we're in an interrupt or have no user | |
70 | * context, we must not take the fault.. | |
71 | */ | |
72 | if (in_atomic() || !mm) | |
73 | goto bad_area_nosemaphore; | |
74 | ||
75 | down_read(&mm->mmap_sem); | |
76 | vma = find_vma(mm, address); | |
77 | if (!vma) | |
78 | goto bad_area; | |
79 | if (vma->vm_start <= address) | |
80 | goto good_area; | |
81 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
82 | goto bad_area; | |
83 | if (expand_stack(vma, address)) | |
84 | goto bad_area; | |
85 | /* | |
86 | * Ok, we have a good vm_area for this memory access, so | |
87 | * we can handle it.. | |
88 | */ | |
89 | good_area: | |
90 | info.si_code = SEGV_ACCERR; | |
91 | ||
92 | if (write) { | |
93 | if (!(vma->vm_flags & VM_WRITE)) | |
94 | goto bad_area; | |
95 | } else { | |
00932ba3 | 96 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) |
1da177e4 LT |
97 | goto bad_area; |
98 | } | |
99 | ||
100 | survive: | |
101 | /* | |
102 | * If for any reason at all we couldn't handle the fault, | |
103 | * make sure we exit gracefully rather than endlessly redo | |
104 | * the fault. | |
105 | */ | |
83c54070 NP |
106 | fault = handle_mm_fault(mm, vma, address, write); |
107 | if (unlikely(fault & VM_FAULT_ERROR)) { | |
108 | if (fault & VM_FAULT_OOM) | |
109 | goto out_of_memory; | |
110 | else if (fault & VM_FAULT_SIGBUS) | |
111 | goto do_sigbus; | |
1da177e4 LT |
112 | BUG(); |
113 | } | |
83c54070 NP |
114 | if (fault & VM_FAULT_MAJOR) |
115 | tsk->maj_flt++; | |
116 | else | |
117 | tsk->min_flt++; | |
1da177e4 LT |
118 | |
119 | up_read(&mm->mmap_sem); | |
120 | return; | |
121 | ||
122 | /* | |
123 | * Something tried to access memory that isn't in our memory map.. | |
124 | * Fix it, but check if it's kernel or user first.. | |
125 | */ | |
126 | bad_area: | |
127 | up_read(&mm->mmap_sem); | |
128 | ||
129 | bad_area_nosemaphore: | |
130 | /* User mode accesses just cause a SIGSEGV */ | |
131 | if (user_mode(regs)) { | |
132 | tsk->thread.cp0_badvaddr = address; | |
133 | tsk->thread.error_code = write; | |
134 | #if 0 | |
135 | printk("do_page_fault() #2: sending SIGSEGV to %s for " | |
136 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", | |
137 | tsk->comm, | |
138 | write ? "write access to" : "read access from", | |
139 | field, address, | |
140 | field, (unsigned long) regs->cp0_epc, | |
141 | field, (unsigned long) regs->regs[31]); | |
142 | #endif | |
143 | info.si_signo = SIGSEGV; | |
144 | info.si_errno = 0; | |
145 | /* info.si_code has been set above */ | |
fe00f943 | 146 | info.si_addr = (void __user *) address; |
1da177e4 LT |
147 | force_sig_info(SIGSEGV, &info, tsk); |
148 | return; | |
149 | } | |
150 | ||
151 | no_context: | |
152 | /* Are we prepared to handle this kernel fault? */ | |
153 | if (fixup_exception(regs)) { | |
154 | current->thread.cp0_baduaddr = address; | |
155 | return; | |
156 | } | |
157 | ||
158 | /* | |
159 | * Oops. The kernel tried to access some bad page. We'll have to | |
160 | * terminate things with extreme prejudice. | |
161 | */ | |
1da177e4 LT |
162 | bust_spinlocks(1); |
163 | ||
164 | printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " | |
165 | "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", | |
d6f70360 | 166 | raw_smp_processor_id(), field, address, field, regs->cp0_epc, |
1da177e4 LT |
167 | field, regs->regs[31]); |
168 | die("Oops", regs); | |
169 | ||
170 | /* | |
171 | * We ran out of memory, or some other thing happened to us that made | |
172 | * us unable to handle the page fault gracefully. | |
173 | */ | |
174 | out_of_memory: | |
175 | up_read(&mm->mmap_sem); | |
f400e198 | 176 | if (is_init(tsk)) { |
1da177e4 LT |
177 | yield(); |
178 | down_read(&mm->mmap_sem); | |
179 | goto survive; | |
180 | } | |
181 | printk("VM: killing process %s\n", tsk->comm); | |
182 | if (user_mode(regs)) | |
183 | do_exit(SIGKILL); | |
184 | goto no_context; | |
185 | ||
186 | do_sigbus: | |
187 | up_read(&mm->mmap_sem); | |
188 | ||
189 | /* Kernel mode? Handle exceptions or die */ | |
190 | if (!user_mode(regs)) | |
191 | goto no_context; | |
41c594ab | 192 | else |
1da177e4 LT |
193 | /* |
194 | * Send a sigbus, regardless of whether we were in kernel | |
195 | * or user mode. | |
196 | */ | |
41c594ab RB |
197 | #if 0 |
198 | printk("do_page_fault() #3: sending SIGBUS to %s for " | |
199 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", | |
200 | tsk->comm, | |
201 | write ? "write access to" : "read access from", | |
202 | field, address, | |
203 | field, (unsigned long) regs->cp0_epc, | |
204 | field, (unsigned long) regs->regs[31]); | |
205 | #endif | |
1da177e4 LT |
206 | tsk->thread.cp0_badvaddr = address; |
207 | info.si_signo = SIGBUS; | |
208 | info.si_errno = 0; | |
209 | info.si_code = BUS_ADRERR; | |
fe00f943 | 210 | info.si_addr = (void __user *) address; |
1da177e4 LT |
211 | force_sig_info(SIGBUS, &info, tsk); |
212 | ||
213 | return; | |
1da177e4 LT |
214 | vmalloc_fault: |
215 | { | |
216 | /* | |
217 | * Synchronize this task's top level page-table | |
218 | * with the 'reference' page table. | |
219 | * | |
220 | * Do _not_ use "tsk" here. We might be inside | |
221 | * an interrupt in the middle of a task switch.. | |
222 | */ | |
223 | int offset = __pgd_offset(address); | |
224 | pgd_t *pgd, *pgd_k; | |
c6e8b587 | 225 | pud_t *pud, *pud_k; |
1da177e4 LT |
226 | pmd_t *pmd, *pmd_k; |
227 | pte_t *pte_k; | |
228 | ||
d6f70360 | 229 | pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; |
1da177e4 LT |
230 | pgd_k = init_mm.pgd + offset; |
231 | ||
232 | if (!pgd_present(*pgd_k)) | |
233 | goto no_context; | |
234 | set_pgd(pgd, *pgd_k); | |
235 | ||
c6e8b587 RB |
236 | pud = pud_offset(pgd, address); |
237 | pud_k = pud_offset(pgd_k, address); | |
238 | if (!pud_present(*pud_k)) | |
239 | goto no_context; | |
240 | ||
241 | pmd = pmd_offset(pud, address); | |
242 | pmd_k = pmd_offset(pud_k, address); | |
1da177e4 LT |
243 | if (!pmd_present(*pmd_k)) |
244 | goto no_context; | |
245 | set_pmd(pmd, *pmd_k); | |
246 | ||
247 | pte_k = pte_offset_kernel(pmd_k, address); | |
248 | if (!pte_present(*pte_k)) | |
249 | goto no_context; | |
250 | return; | |
251 | } | |
252 | } |