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6bc9a396 CL |
1 | /* |
2 | * arch/score/mm/fault.c | |
3 | * | |
4 | * Score Processor version. | |
5 | * | |
6 | * Copyright (C) 2009 Sunplus Core Technology Co., Ltd. | |
7 | * Lennox Wu <lennox.wu@sunplusct.com> | |
8 | * Chen Liqin <liqin.chen@sunplusct.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License as published by | |
12 | * the Free Software Foundation; either version 2 of the License, or | |
13 | * (at your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, | |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | * GNU General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public License | |
21 | * along with this program; if not, see the file COPYING, or write | |
22 | * to the Free Software Foundation, Inc., | |
23 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
24 | */ | |
25 | ||
26 | #include <linux/errno.h> | |
27 | #include <linux/interrupt.h> | |
28 | #include <linux/kernel.h> | |
29 | #include <linux/mm.h> | |
30 | #include <linux/mman.h> | |
31 | #include <linux/module.h> | |
32 | #include <linux/signal.h> | |
33 | #include <linux/sched.h> | |
34 | #include <linux/string.h> | |
35 | #include <linux/types.h> | |
36 | #include <linux/ptrace.h> | |
37 | ||
38 | /* | |
39 | * This routine handles page faults. It determines the address, | |
40 | * and the problem, and then passes it off to one of the appropriate | |
41 | * routines. | |
42 | */ | |
43 | asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, | |
44 | unsigned long address) | |
45 | { | |
46 | struct vm_area_struct *vma = NULL; | |
47 | struct task_struct *tsk = current; | |
48 | struct mm_struct *mm = tsk->mm; | |
49 | const int field = sizeof(unsigned long) * 2; | |
50 | siginfo_t info; | |
51 | int fault; | |
52 | ||
53 | info.si_code = SEGV_MAPERR; | |
54 | ||
55 | /* | |
56 | * We fault-in kernel-space virtual memory on-demand. The | |
57 | * 'reference' page table is init_mm.pgd. | |
58 | * | |
59 | * NOTE! We MUST NOT take any locks for this case. We may | |
60 | * be in an interrupt or a critical region, and should | |
61 | * only copy the information from the master page table, | |
62 | * nothing more. | |
63 | */ | |
64 | if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) | |
65 | goto vmalloc_fault; | |
66 | #ifdef MODULE_START | |
67 | if (unlikely(address >= MODULE_START && address < MODULE_END)) | |
68 | goto vmalloc_fault; | |
69 | #endif | |
70 | ||
71 | /* | |
72 | * If we're in an interrupt or have no user | |
73 | * context, we must not take the fault.. | |
74 | */ | |
75 | if (in_atomic() || !mm) | |
76 | goto bad_area_nosemaphore; | |
77 | ||
78 | down_read(&mm->mmap_sem); | |
79 | vma = find_vma(mm, address); | |
80 | if (!vma) | |
81 | goto bad_area; | |
82 | if (vma->vm_start <= address) | |
83 | goto good_area; | |
84 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
85 | goto bad_area; | |
86 | if (expand_stack(vma, address)) | |
87 | goto bad_area; | |
88 | /* | |
89 | * Ok, we have a good vm_area for this memory access, so | |
90 | * we can handle it.. | |
91 | */ | |
92 | good_area: | |
93 | info.si_code = SEGV_ACCERR; | |
94 | ||
95 | if (write) { | |
96 | if (!(vma->vm_flags & VM_WRITE)) | |
97 | goto bad_area; | |
98 | } else { | |
99 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) | |
100 | goto bad_area; | |
101 | } | |
102 | ||
103 | survive: | |
104 | /* | |
105 | * If for any reason at all we couldn't handle the fault, | |
106 | * make sure we exit gracefully rather than endlessly redo | |
107 | * the fault. | |
108 | */ | |
109 | fault = handle_mm_fault(mm, vma, address, write); | |
110 | if (unlikely(fault & VM_FAULT_ERROR)) { | |
111 | if (fault & VM_FAULT_OOM) | |
112 | goto out_of_memory; | |
113 | else if (fault & VM_FAULT_SIGBUS) | |
114 | goto do_sigbus; | |
115 | BUG(); | |
116 | } | |
117 | if (fault & VM_FAULT_MAJOR) | |
118 | tsk->maj_flt++; | |
119 | else | |
120 | tsk->min_flt++; | |
121 | ||
122 | up_read(&mm->mmap_sem); | |
123 | return; | |
124 | ||
125 | /* | |
126 | * Something tried to access memory that isn't in our memory map.. | |
127 | * Fix it, but check if it's kernel or user first.. | |
128 | */ | |
129 | bad_area: | |
130 | up_read(&mm->mmap_sem); | |
131 | ||
132 | bad_area_nosemaphore: | |
133 | /* User mode accesses just cause a SIGSEGV */ | |
134 | if (user_mode(regs)) { | |
135 | tsk->thread.cp0_badvaddr = address; | |
136 | tsk->thread.error_code = write; | |
137 | info.si_signo = SIGSEGV; | |
138 | info.si_errno = 0; | |
139 | /* info.si_code has been set above */ | |
140 | info.si_addr = (void __user *) address; | |
141 | force_sig_info(SIGSEGV, &info, tsk); | |
142 | return; | |
143 | } | |
144 | ||
145 | no_context: | |
146 | /* Are we prepared to handle this kernel fault? */ | |
147 | if (fixup_exception(regs)) { | |
148 | current->thread.cp0_baduaddr = address; | |
149 | return; | |
150 | } | |
151 | ||
152 | /* | |
153 | * Oops. The kernel tried to access some bad page. We'll have to | |
154 | * terminate things with extreme prejudice. | |
155 | */ | |
156 | bust_spinlocks(1); | |
157 | ||
158 | printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " | |
159 | "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", | |
160 | 0, field, address, field, regs->cp0_epc, | |
161 | field, regs->regs[3]); | |
162 | die("Oops", regs); | |
163 | ||
164 | /* | |
165 | * We ran out of memory, or some other thing happened to us that made | |
166 | * us unable to handle the page fault gracefully. | |
167 | */ | |
168 | out_of_memory: | |
169 | up_read(&mm->mmap_sem); | |
170 | if (is_global_init(tsk)) { | |
171 | yield(); | |
172 | down_read(&mm->mmap_sem); | |
173 | goto survive; | |
174 | } | |
175 | printk("VM: killing process %s\n", tsk->comm); | |
176 | if (user_mode(regs)) | |
177 | do_group_exit(SIGKILL); | |
178 | goto no_context; | |
179 | ||
180 | do_sigbus: | |
181 | up_read(&mm->mmap_sem); | |
182 | /* Kernel mode? Handle exceptions or die */ | |
183 | if (!user_mode(regs)) | |
184 | goto no_context; | |
185 | else | |
186 | /* | |
187 | * Send a sigbus, regardless of whether we were in kernel | |
188 | * or user mode. | |
189 | */ | |
190 | tsk->thread.cp0_badvaddr = address; | |
191 | info.si_signo = SIGBUS; | |
192 | info.si_errno = 0; | |
193 | info.si_code = BUS_ADRERR; | |
194 | info.si_addr = (void __user *) address; | |
195 | force_sig_info(SIGBUS, &info, tsk); | |
196 | return; | |
197 | vmalloc_fault: | |
198 | { | |
199 | /* | |
200 | * Synchronize this task's top level page-table | |
201 | * with the 'reference' page table. | |
202 | * | |
203 | * Do _not_ use "tsk" here. We might be inside | |
204 | * an interrupt in the middle of a task switch.. | |
205 | */ | |
206 | int offset = __pgd_offset(address); | |
207 | pgd_t *pgd, *pgd_k; | |
208 | pud_t *pud, *pud_k; | |
209 | pmd_t *pmd, *pmd_k; | |
210 | pte_t *pte_k; | |
211 | ||
212 | pgd = (pgd_t *) pgd_current + offset; | |
213 | pgd_k = init_mm.pgd + offset; | |
214 | ||
215 | if (!pgd_present(*pgd_k)) | |
216 | goto no_context; | |
217 | set_pgd(pgd, *pgd_k); | |
218 | ||
219 | pud = pud_offset(pgd, address); | |
220 | pud_k = pud_offset(pgd_k, address); | |
221 | if (!pud_present(*pud_k)) | |
222 | goto no_context; | |
223 | ||
224 | pmd = pmd_offset(pud, address); | |
225 | pmd_k = pmd_offset(pud_k, address); | |
226 | if (!pmd_present(*pmd_k)) | |
227 | goto no_context; | |
228 | set_pmd(pmd, *pmd_k); | |
229 | ||
230 | pte_k = pte_offset_kernel(pmd_k, address); | |
231 | if (!pte_present(*pte_k)) | |
232 | goto no_context; | |
233 | return; | |
234 | } | |
235 | } |