blob: 47b600e4b2c50ae853b72404f3e1b051dce15f53 [file] [log] [blame]
Chen Liqin6bc9a392009-06-12 22:01:00 +08001/*
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 */
43asmlinkage 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 */
92good_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
103survive:
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 */
129bad_area:
130 up_read(&mm->mmap_sem);
131
132bad_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
145no_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 */
168out_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
180do_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;
197vmalloc_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}