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5f97f7f9 HS |
1 | /* |
2 | * Copyright (C) 2004-2006 Atmel Corporation | |
3 | * | |
4 | * Based on linux/arch/sh/mm/fault.c: | |
5 | * Copyright (C) 1999 Niibe Yutaka | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #include <linux/mm.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/pagemap.h> | |
1eeb66a1 | 15 | #include <linux/kdebug.h> |
9caebec7 | 16 | #include <linux/kprobes.h> |
70ffdb93 | 17 | #include <linux/uaccess.h> |
9caebec7 | 18 | |
5f97f7f9 HS |
19 | #include <asm/mmu_context.h> |
20 | #include <asm/sysreg.h> | |
5f97f7f9 | 21 | #include <asm/tlb.h> |
5f97f7f9 HS |
22 | |
23 | #ifdef CONFIG_KPROBES | |
9caebec7 | 24 | static inline int notify_page_fault(struct pt_regs *regs, int trap) |
5f97f7f9 | 25 | { |
9caebec7 | 26 | int ret = 0; |
5f97f7f9 | 27 | |
9caebec7 CH |
28 | if (!user_mode(regs)) { |
29 | if (kprobe_running() && kprobe_fault_handler(regs, trap)) | |
30 | ret = 1; | |
31 | } | |
5f97f7f9 | 32 | |
9caebec7 | 33 | return ret; |
5f97f7f9 HS |
34 | } |
35 | #else | |
9caebec7 | 36 | static inline int notify_page_fault(struct pt_regs *regs, int trap) |
5f97f7f9 | 37 | { |
9caebec7 | 38 | return 0; |
5f97f7f9 HS |
39 | } |
40 | #endif | |
41 | ||
623b0355 HS |
42 | int exception_trace = 1; |
43 | ||
5f97f7f9 HS |
44 | /* |
45 | * This routine handles page faults. It determines the address and the | |
46 | * problem, and then passes it off to one of the appropriate routines. | |
47 | * | |
48 | * ecr is the Exception Cause Register. Possible values are: | |
5f97f7f9 | 49 | * 6: Protection fault (instruction access) |
623b0355 HS |
50 | * 15: Protection fault (read access) |
51 | * 16: Protection fault (write access) | |
52 | * 20: Page not found (instruction access) | |
53 | * 24: Page not found (read access) | |
54 | * 28: Page not found (write access) | |
5f97f7f9 HS |
55 | */ |
56 | asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs) | |
57 | { | |
58 | struct task_struct *tsk; | |
59 | struct mm_struct *mm; | |
60 | struct vm_area_struct *vma; | |
61 | const struct exception_table_entry *fixup; | |
62 | unsigned long address; | |
63 | unsigned long page; | |
623b0355 HS |
64 | long signr; |
65 | int code; | |
83c54070 | 66 | int fault; |
bf7c27e9 | 67 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
5f97f7f9 | 68 | |
9caebec7 | 69 | if (notify_page_fault(regs, ecr)) |
5f97f7f9 HS |
70 | return; |
71 | ||
72 | address = sysreg_read(TLBEAR); | |
73 | ||
74 | tsk = current; | |
75 | mm = tsk->mm; | |
76 | ||
623b0355 HS |
77 | signr = SIGSEGV; |
78 | code = SEGV_MAPERR; | |
79 | ||
5f97f7f9 HS |
80 | /* |
81 | * If we're in an interrupt or have no user context, we must | |
82 | * not take the fault... | |
83 | */ | |
70ffdb93 | 84 | if (faulthandler_disabled() || !mm || regs->sr & SYSREG_BIT(GM)) |
5f97f7f9 HS |
85 | goto no_context; |
86 | ||
87 | local_irq_enable(); | |
88 | ||
759496ba JW |
89 | if (user_mode(regs)) |
90 | flags |= FAULT_FLAG_USER; | |
bf7c27e9 | 91 | retry: |
5f97f7f9 HS |
92 | down_read(&mm->mmap_sem); |
93 | ||
94 | vma = find_vma(mm, address); | |
95 | if (!vma) | |
96 | goto bad_area; | |
97 | if (vma->vm_start <= address) | |
98 | goto good_area; | |
99 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
100 | goto bad_area; | |
101 | if (expand_stack(vma, address)) | |
102 | goto bad_area; | |
103 | ||
104 | /* | |
105 | * Ok, we have a good vm_area for this memory access, so we | |
106 | * can handle it... | |
107 | */ | |
108 | good_area: | |
623b0355 | 109 | code = SEGV_ACCERR; |
623b0355 | 110 | |
5f97f7f9 HS |
111 | switch (ecr) { |
112 | case ECR_PROTECTION_X: | |
113 | case ECR_TLB_MISS_X: | |
114 | if (!(vma->vm_flags & VM_EXEC)) | |
115 | goto bad_area; | |
116 | break; | |
117 | case ECR_PROTECTION_R: | |
118 | case ECR_TLB_MISS_R: | |
119 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) | |
120 | goto bad_area; | |
121 | break; | |
122 | case ECR_PROTECTION_W: | |
123 | case ECR_TLB_MISS_W: | |
124 | if (!(vma->vm_flags & VM_WRITE)) | |
125 | goto bad_area; | |
bf7c27e9 | 126 | flags |= FAULT_FLAG_WRITE; |
5f97f7f9 HS |
127 | break; |
128 | default: | |
129 | panic("Unhandled case %lu in do_page_fault!", ecr); | |
130 | } | |
131 | ||
132 | /* | |
133 | * If for any reason at all we couldn't handle the fault, make | |
134 | * sure we exit gracefully rather than endlessly redo the | |
135 | * fault. | |
136 | */ | |
bf7c27e9 KC |
137 | fault = handle_mm_fault(mm, vma, address, flags); |
138 | ||
139 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
140 | return; | |
141 | ||
83c54070 NP |
142 | if (unlikely(fault & VM_FAULT_ERROR)) { |
143 | if (fault & VM_FAULT_OOM) | |
144 | goto out_of_memory; | |
33692f27 LT |
145 | else if (fault & VM_FAULT_SIGSEGV) |
146 | goto bad_area; | |
83c54070 NP |
147 | else if (fault & VM_FAULT_SIGBUS) |
148 | goto do_sigbus; | |
5f97f7f9 HS |
149 | BUG(); |
150 | } | |
bf7c27e9 KC |
151 | |
152 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
153 | if (fault & VM_FAULT_MAJOR) | |
154 | tsk->maj_flt++; | |
155 | else | |
156 | tsk->min_flt++; | |
157 | if (fault & VM_FAULT_RETRY) { | |
158 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 159 | flags |= FAULT_FLAG_TRIED; |
bf7c27e9 KC |
160 | |
161 | /* | |
162 | * No need to up_read(&mm->mmap_sem) as we would have | |
163 | * already released it in __lock_page_or_retry() in | |
164 | * mm/filemap.c. | |
165 | */ | |
166 | goto retry; | |
167 | } | |
168 | } | |
5f97f7f9 HS |
169 | |
170 | up_read(&mm->mmap_sem); | |
171 | return; | |
172 | ||
173 | /* | |
174 | * Something tried to access memory that isn't in our memory | |
175 | * map. Fix it, but check if it's kernel or user first... | |
176 | */ | |
177 | bad_area: | |
5f97f7f9 HS |
178 | up_read(&mm->mmap_sem); |
179 | ||
180 | if (user_mode(regs)) { | |
126187f1 | 181 | if (exception_trace && printk_ratelimit()) |
623b0355 HS |
182 | printk("%s%s[%d]: segfault at %08lx pc %08lx " |
183 | "sp %08lx ecr %lu\n", | |
b460cbc5 | 184 | is_global_init(tsk) ? KERN_EMERG : KERN_INFO, |
623b0355 HS |
185 | tsk->comm, tsk->pid, address, regs->pc, |
186 | regs->sp, ecr); | |
187 | _exception(SIGSEGV, regs, code, address); | |
5f97f7f9 HS |
188 | return; |
189 | } | |
190 | ||
191 | no_context: | |
5f97f7f9 HS |
192 | /* Are we prepared to handle this kernel fault? */ |
193 | fixup = search_exception_tables(regs->pc); | |
194 | if (fixup) { | |
195 | regs->pc = fixup->fixup; | |
5f97f7f9 HS |
196 | return; |
197 | } | |
198 | ||
199 | /* | |
200 | * Oops. The kernel tried to access some bad page. We'll have | |
201 | * to terminate things with extreme prejudice. | |
202 | */ | |
203 | if (address < PAGE_SIZE) | |
204 | printk(KERN_ALERT | |
205 | "Unable to handle kernel NULL pointer dereference"); | |
206 | else | |
207 | printk(KERN_ALERT | |
208 | "Unable to handle kernel paging request"); | |
209 | printk(" at virtual address %08lx\n", address); | |
5f97f7f9 HS |
210 | |
211 | page = sysreg_read(PTBR); | |
212 | printk(KERN_ALERT "ptbr = %08lx", page); | |
32019828 HS |
213 | if (address >= TASK_SIZE) |
214 | page = (unsigned long)swapper_pg_dir; | |
5f97f7f9 HS |
215 | if (page) { |
216 | page = ((unsigned long *)page)[address >> 22]; | |
217 | printk(" pgd = %08lx", page); | |
218 | if (page & _PAGE_PRESENT) { | |
219 | page &= PAGE_MASK; | |
220 | address &= 0x003ff000; | |
221 | page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT]; | |
623b0355 | 222 | printk(" pte = %08lx", page); |
5f97f7f9 HS |
223 | } |
224 | } | |
623b0355 HS |
225 | printk("\n"); |
226 | die("Kernel access of bad area", regs, signr); | |
227 | return; | |
5f97f7f9 HS |
228 | |
229 | /* | |
230 | * We ran out of memory, or some other thing happened to us | |
231 | * that made us unable to handle the page fault gracefully. | |
232 | */ | |
233 | out_of_memory: | |
5f97f7f9 | 234 | up_read(&mm->mmap_sem); |
67a8a20f NP |
235 | if (!user_mode(regs)) |
236 | goto no_context; | |
87134102 | 237 | pagefault_out_of_memory(); |
67a8a20f | 238 | return; |
5f97f7f9 HS |
239 | |
240 | do_sigbus: | |
241 | up_read(&mm->mmap_sem); | |
242 | ||
5f97f7f9 | 243 | /* Kernel mode? Handle exceptions or die */ |
623b0355 HS |
244 | signr = SIGBUS; |
245 | code = BUS_ADRERR; | |
5f97f7f9 HS |
246 | if (!user_mode(regs)) |
247 | goto no_context; | |
623b0355 HS |
248 | |
249 | if (exception_trace) | |
250 | printk("%s%s[%d]: bus error at %08lx pc %08lx " | |
251 | "sp %08lx ecr %lu\n", | |
b460cbc5 | 252 | is_global_init(tsk) ? KERN_EMERG : KERN_INFO, |
623b0355 HS |
253 | tsk->comm, tsk->pid, address, regs->pc, |
254 | regs->sp, ecr); | |
255 | ||
256 | _exception(SIGBUS, regs, BUS_ADRERR, address); | |
5f97f7f9 HS |
257 | } |
258 | ||
259 | asmlinkage void do_bus_error(unsigned long addr, int write_access, | |
260 | struct pt_regs *regs) | |
261 | { | |
262 | printk(KERN_ALERT | |
263 | "Bus error at physical address 0x%08lx (%s access)\n", | |
264 | addr, write_access ? "write" : "read"); | |
265 | printk(KERN_INFO "DTLB dump:\n"); | |
266 | dump_dtlb(); | |
623b0355 | 267 | die("Bus Error", regs, SIGKILL); |
5f97f7f9 | 268 | } |