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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; | |
42 | ||
43 | #if 0 | |
d6f70360 | 44 | printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), |
1da177e4 LT |
45 | current->comm, current->pid, field, address, write, |
46 | field, regs->cp0_epc); | |
47 | #endif | |
48 | ||
49 | info.si_code = SEGV_MAPERR; | |
50 | ||
51 | /* | |
52 | * We fault-in kernel-space virtual memory on-demand. The | |
53 | * 'reference' page table is init_mm.pgd. | |
54 | * | |
55 | * NOTE! We MUST NOT take any locks for this case. We may | |
56 | * be in an interrupt or a critical region, and should | |
57 | * only copy the information from the master page table, | |
58 | * nothing more. | |
59 | */ | |
16033d61 | 60 | if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) |
1da177e4 | 61 | goto vmalloc_fault; |
656be92f AN |
62 | #ifdef MODULE_START |
63 | if (unlikely(address >= MODULE_START && address < MODULE_END)) | |
64 | goto vmalloc_fault; | |
65 | #endif | |
1da177e4 LT |
66 | |
67 | /* | |
68 | * If we're in an interrupt or have no user | |
69 | * context, we must not take the fault.. | |
70 | */ | |
71 | if (in_atomic() || !mm) | |
72 | goto bad_area_nosemaphore; | |
73 | ||
74 | down_read(&mm->mmap_sem); | |
75 | vma = find_vma(mm, address); | |
76 | if (!vma) | |
77 | goto bad_area; | |
78 | if (vma->vm_start <= address) | |
79 | goto good_area; | |
80 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
81 | goto bad_area; | |
82 | if (expand_stack(vma, address)) | |
83 | goto bad_area; | |
84 | /* | |
85 | * Ok, we have a good vm_area for this memory access, so | |
86 | * we can handle it.. | |
87 | */ | |
88 | good_area: | |
89 | info.si_code = SEGV_ACCERR; | |
90 | ||
91 | if (write) { | |
92 | if (!(vma->vm_flags & VM_WRITE)) | |
93 | goto bad_area; | |
94 | } else { | |
00932ba3 | 95 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) |
1da177e4 LT |
96 | goto bad_area; |
97 | } | |
98 | ||
99 | survive: | |
100 | /* | |
101 | * If for any reason at all we couldn't handle the fault, | |
102 | * make sure we exit gracefully rather than endlessly redo | |
103 | * the fault. | |
104 | */ | |
105 | switch (handle_mm_fault(mm, vma, address, write)) { | |
106 | case VM_FAULT_MINOR: | |
107 | tsk->min_flt++; | |
108 | break; | |
109 | case VM_FAULT_MAJOR: | |
110 | tsk->maj_flt++; | |
111 | break; | |
112 | case VM_FAULT_SIGBUS: | |
113 | goto do_sigbus; | |
114 | case VM_FAULT_OOM: | |
115 | goto out_of_memory; | |
116 | default: | |
117 | BUG(); | |
118 | } | |
119 | ||
120 | up_read(&mm->mmap_sem); | |
121 | return; | |
122 | ||
123 | /* | |
124 | * Something tried to access memory that isn't in our memory map.. | |
125 | * Fix it, but check if it's kernel or user first.. | |
126 | */ | |
127 | bad_area: | |
128 | up_read(&mm->mmap_sem); | |
129 | ||
130 | bad_area_nosemaphore: | |
131 | /* User mode accesses just cause a SIGSEGV */ | |
132 | if (user_mode(regs)) { | |
133 | tsk->thread.cp0_badvaddr = address; | |
134 | tsk->thread.error_code = write; | |
135 | #if 0 | |
136 | printk("do_page_fault() #2: sending SIGSEGV to %s for " | |
137 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", | |
138 | tsk->comm, | |
139 | write ? "write access to" : "read access from", | |
140 | field, address, | |
141 | field, (unsigned long) regs->cp0_epc, | |
142 | field, (unsigned long) regs->regs[31]); | |
143 | #endif | |
144 | info.si_signo = SIGSEGV; | |
145 | info.si_errno = 0; | |
146 | /* info.si_code has been set above */ | |
fe00f943 | 147 | info.si_addr = (void __user *) address; |
1da177e4 LT |
148 | force_sig_info(SIGSEGV, &info, tsk); |
149 | return; | |
150 | } | |
151 | ||
152 | no_context: | |
153 | /* Are we prepared to handle this kernel fault? */ | |
154 | if (fixup_exception(regs)) { | |
155 | current->thread.cp0_baduaddr = address; | |
156 | return; | |
157 | } | |
158 | ||
159 | /* | |
160 | * Oops. The kernel tried to access some bad page. We'll have to | |
161 | * terminate things with extreme prejudice. | |
162 | */ | |
1da177e4 LT |
163 | bust_spinlocks(1); |
164 | ||
165 | printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " | |
166 | "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", | |
d6f70360 | 167 | raw_smp_processor_id(), field, address, field, regs->cp0_epc, |
1da177e4 LT |
168 | field, regs->regs[31]); |
169 | die("Oops", regs); | |
170 | ||
171 | /* | |
172 | * We ran out of memory, or some other thing happened to us that made | |
173 | * us unable to handle the page fault gracefully. | |
174 | */ | |
175 | out_of_memory: | |
176 | up_read(&mm->mmap_sem); | |
f400e198 | 177 | if (is_init(tsk)) { |
1da177e4 LT |
178 | yield(); |
179 | down_read(&mm->mmap_sem); | |
180 | goto survive; | |
181 | } | |
182 | printk("VM: killing process %s\n", tsk->comm); | |
183 | if (user_mode(regs)) | |
184 | do_exit(SIGKILL); | |
185 | goto no_context; | |
186 | ||
187 | do_sigbus: | |
188 | up_read(&mm->mmap_sem); | |
189 | ||
190 | /* Kernel mode? Handle exceptions or die */ | |
191 | if (!user_mode(regs)) | |
192 | goto no_context; | |
41c594ab | 193 | else |
1da177e4 LT |
194 | /* |
195 | * Send a sigbus, regardless of whether we were in kernel | |
196 | * or user mode. | |
197 | */ | |
41c594ab RB |
198 | #if 0 |
199 | printk("do_page_fault() #3: sending SIGBUS to %s for " | |
200 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", | |
201 | tsk->comm, | |
202 | write ? "write access to" : "read access from", | |
203 | field, address, | |
204 | field, (unsigned long) regs->cp0_epc, | |
205 | field, (unsigned long) regs->regs[31]); | |
206 | #endif | |
1da177e4 LT |
207 | tsk->thread.cp0_badvaddr = address; |
208 | info.si_signo = SIGBUS; | |
209 | info.si_errno = 0; | |
210 | info.si_code = BUS_ADRERR; | |
fe00f943 | 211 | info.si_addr = (void __user *) address; |
1da177e4 LT |
212 | force_sig_info(SIGBUS, &info, tsk); |
213 | ||
214 | return; | |
1da177e4 LT |
215 | vmalloc_fault: |
216 | { | |
217 | /* | |
218 | * Synchronize this task's top level page-table | |
219 | * with the 'reference' page table. | |
220 | * | |
221 | * Do _not_ use "tsk" here. We might be inside | |
222 | * an interrupt in the middle of a task switch.. | |
223 | */ | |
224 | int offset = __pgd_offset(address); | |
225 | pgd_t *pgd, *pgd_k; | |
c6e8b587 | 226 | pud_t *pud, *pud_k; |
1da177e4 LT |
227 | pmd_t *pmd, *pmd_k; |
228 | pte_t *pte_k; | |
229 | ||
d6f70360 | 230 | pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; |
1da177e4 LT |
231 | pgd_k = init_mm.pgd + offset; |
232 | ||
233 | if (!pgd_present(*pgd_k)) | |
234 | goto no_context; | |
235 | set_pgd(pgd, *pgd_k); | |
236 | ||
c6e8b587 RB |
237 | pud = pud_offset(pgd, address); |
238 | pud_k = pud_offset(pgd_k, address); | |
239 | if (!pud_present(*pud_k)) | |
240 | goto no_context; | |
241 | ||
242 | pmd = pmd_offset(pud, address); | |
243 | pmd_k = pmd_offset(pud_k, address); | |
1da177e4 LT |
244 | if (!pmd_present(*pmd_k)) |
245 | goto no_context; | |
246 | set_pmd(pmd, *pmd_k); | |
247 | ||
248 | pte_k = pte_offset_kernel(pmd_k, address); | |
249 | if (!pte_present(*pte_k)) | |
250 | goto no_context; | |
251 | return; | |
252 | } | |
253 | } |