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1da177e4 LT |
1 | /* |
2 | * linux/arch/alpha/mm/fault.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | */ | |
6 | ||
1da177e4 LT |
7 | #include <linux/sched.h> |
8 | #include <linux/kernel.h> | |
9 | #include <linux/mm.h> | |
10 | #include <asm/io.h> | |
11 | ||
12 | #define __EXTERN_INLINE inline | |
13 | #include <asm/mmu_context.h> | |
14 | #include <asm/tlbflush.h> | |
15 | #undef __EXTERN_INLINE | |
16 | ||
17 | #include <linux/signal.h> | |
18 | #include <linux/errno.h> | |
19 | #include <linux/string.h> | |
20 | #include <linux/types.h> | |
21 | #include <linux/ptrace.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/smp.h> | |
1da177e4 LT |
24 | #include <linux/interrupt.h> |
25 | #include <linux/module.h> | |
70ffdb93 | 26 | #include <linux/uaccess.h> |
1da177e4 LT |
27 | |
28 | extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *); | |
29 | ||
30 | ||
31 | /* | |
32 | * Force a new ASN for a task. | |
33 | */ | |
34 | ||
35 | #ifndef CONFIG_SMP | |
36 | unsigned long last_asn = ASN_FIRST_VERSION; | |
37 | #endif | |
38 | ||
39 | void | |
40 | __load_new_mm_context(struct mm_struct *next_mm) | |
41 | { | |
42 | unsigned long mmc; | |
43 | struct pcb_struct *pcb; | |
44 | ||
45 | mmc = __get_new_mm_context(next_mm, smp_processor_id()); | |
46 | next_mm->context[smp_processor_id()] = mmc; | |
47 | ||
48 | pcb = ¤t_thread_info()->pcb; | |
49 | pcb->asn = mmc & HARDWARE_ASN_MASK; | |
50 | pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; | |
51 | ||
52 | __reload_thread(pcb); | |
53 | } | |
54 | ||
55 | ||
56 | /* | |
57 | * This routine handles page faults. It determines the address, | |
58 | * and the problem, and then passes it off to handle_mm_fault(). | |
59 | * | |
60 | * mmcsr: | |
61 | * 0 = translation not valid | |
62 | * 1 = access violation | |
63 | * 2 = fault-on-read | |
64 | * 3 = fault-on-execute | |
65 | * 4 = fault-on-write | |
66 | * | |
67 | * cause: | |
68 | * -1 = instruction fetch | |
69 | * 0 = load | |
70 | * 1 = store | |
71 | * | |
72 | * Registers $9 through $15 are saved in a block just prior to `regs' and | |
73 | * are saved and restored around the call to allow exception code to | |
74 | * modify them. | |
75 | */ | |
76 | ||
77 | /* Macro for exception fixup code to access integer registers. */ | |
78 | #define dpf_reg(r) \ | |
79 | (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \ | |
80 | (r) <= 18 ? (r)+8 : (r)-10]) | |
81 | ||
82 | asmlinkage void | |
83 | do_page_fault(unsigned long address, unsigned long mmcsr, | |
84 | long cause, struct pt_regs *regs) | |
85 | { | |
86 | struct vm_area_struct * vma; | |
87 | struct mm_struct *mm = current->mm; | |
88 | const struct exception_table_entry *fixup; | |
89 | int fault, si_code = SEGV_MAPERR; | |
90 | siginfo_t info; | |
759496ba | 91 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
1da177e4 LT |
92 | |
93 | /* As of EV6, a load into $31/$f31 is a prefetch, and never faults | |
94 | (or is suppressed by the PALcode). Support that for older CPUs | |
95 | by ignoring such an instruction. */ | |
96 | if (cause == 0) { | |
97 | unsigned int insn; | |
98 | __get_user(insn, (unsigned int __user *)regs->pc); | |
99 | if ((insn >> 21 & 0x1f) == 0x1f && | |
100 | /* ldq ldl ldt lds ldg ldf ldwu ldbu */ | |
101 | (1ul << (insn >> 26) & 0x30f00001400ul)) { | |
102 | regs->pc += 4; | |
103 | return; | |
104 | } | |
105 | } | |
106 | ||
107 | /* If we're in an interrupt context, or have no user context, | |
108 | we must not take the fault. */ | |
70ffdb93 | 109 | if (!mm || faulthandler_disabled()) |
1da177e4 LT |
110 | goto no_context; |
111 | ||
112 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
113 | if (address >= TASK_SIZE) | |
114 | goto vmalloc_fault; | |
115 | #endif | |
759496ba JW |
116 | if (user_mode(regs)) |
117 | flags |= FAULT_FLAG_USER; | |
0bcc426b | 118 | retry: |
1da177e4 LT |
119 | down_read(&mm->mmap_sem); |
120 | vma = find_vma(mm, address); | |
121 | if (!vma) | |
122 | goto bad_area; | |
123 | if (vma->vm_start <= address) | |
124 | goto good_area; | |
125 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
126 | goto bad_area; | |
127 | if (expand_stack(vma, address)) | |
128 | goto bad_area; | |
129 | ||
130 | /* Ok, we have a good vm_area for this memory access, so | |
131 | we can handle it. */ | |
132 | good_area: | |
133 | si_code = SEGV_ACCERR; | |
134 | if (cause < 0) { | |
135 | if (!(vma->vm_flags & VM_EXEC)) | |
136 | goto bad_area; | |
137 | } else if (!cause) { | |
138 | /* Allow reads even for write-only mappings */ | |
139 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) | |
140 | goto bad_area; | |
141 | } else { | |
142 | if (!(vma->vm_flags & VM_WRITE)) | |
143 | goto bad_area; | |
759496ba | 144 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
145 | } |
146 | ||
1da177e4 LT |
147 | /* If for any reason at all we couldn't handle the fault, |
148 | make sure we exit gracefully rather than endlessly redo | |
149 | the fault. */ | |
0bcc426b KC |
150 | fault = handle_mm_fault(mm, vma, address, flags); |
151 | ||
152 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
153 | return; | |
154 | ||
83c54070 NP |
155 | if (unlikely(fault & VM_FAULT_ERROR)) { |
156 | if (fault & VM_FAULT_OOM) | |
157 | goto out_of_memory; | |
33692f27 LT |
158 | else if (fault & VM_FAULT_SIGSEGV) |
159 | goto bad_area; | |
83c54070 NP |
160 | else if (fault & VM_FAULT_SIGBUS) |
161 | goto do_sigbus; | |
1da177e4 LT |
162 | BUG(); |
163 | } | |
0bcc426b KC |
164 | |
165 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
166 | if (fault & VM_FAULT_MAJOR) | |
167 | current->maj_flt++; | |
168 | else | |
169 | current->min_flt++; | |
170 | if (fault & VM_FAULT_RETRY) { | |
171 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
172 | ||
173 | /* No need to up_read(&mm->mmap_sem) as we would | |
174 | * have already released it in __lock_page_or_retry | |
175 | * in mm/filemap.c. | |
176 | */ | |
177 | ||
178 | goto retry; | |
179 | } | |
180 | } | |
181 | ||
182 | up_read(&mm->mmap_sem); | |
183 | ||
1da177e4 LT |
184 | return; |
185 | ||
186 | /* Something tried to access memory that isn't in our memory map. | |
187 | Fix it, but check if it's kernel or user first. */ | |
188 | bad_area: | |
189 | up_read(&mm->mmap_sem); | |
190 | ||
191 | if (user_mode(regs)) | |
192 | goto do_sigsegv; | |
193 | ||
194 | no_context: | |
195 | /* Are we prepared to handle this fault as an exception? */ | |
196 | if ((fixup = search_exception_tables(regs->pc)) != 0) { | |
197 | unsigned long newpc; | |
198 | newpc = fixup_exception(dpf_reg, fixup, regs->pc); | |
199 | regs->pc = newpc; | |
200 | return; | |
201 | } | |
202 | ||
203 | /* Oops. The kernel tried to access some bad page. We'll have to | |
204 | terminate things with extreme prejudice. */ | |
205 | printk(KERN_ALERT "Unable to handle kernel paging request at " | |
206 | "virtual address %016lx\n", address); | |
207 | die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16); | |
208 | do_exit(SIGKILL); | |
209 | ||
210 | /* We ran out of memory, or some other thing happened to us that | |
211 | made us unable to handle the page fault gracefully. */ | |
212 | out_of_memory: | |
0bcc426b | 213 | up_read(&mm->mmap_sem); |
1da177e4 LT |
214 | if (!user_mode(regs)) |
215 | goto no_context; | |
1cb3d8e2 NP |
216 | pagefault_out_of_memory(); |
217 | return; | |
1da177e4 LT |
218 | |
219 | do_sigbus: | |
0bcc426b | 220 | up_read(&mm->mmap_sem); |
1da177e4 LT |
221 | /* Send a sigbus, regardless of whether we were in kernel |
222 | or user mode. */ | |
223 | info.si_signo = SIGBUS; | |
224 | info.si_errno = 0; | |
225 | info.si_code = BUS_ADRERR; | |
226 | info.si_addr = (void __user *) address; | |
227 | force_sig_info(SIGBUS, &info, current); | |
228 | if (!user_mode(regs)) | |
229 | goto no_context; | |
230 | return; | |
231 | ||
232 | do_sigsegv: | |
233 | info.si_signo = SIGSEGV; | |
234 | info.si_errno = 0; | |
235 | info.si_code = si_code; | |
236 | info.si_addr = (void __user *) address; | |
237 | force_sig_info(SIGSEGV, &info, current); | |
238 | return; | |
239 | ||
240 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
241 | vmalloc_fault: | |
242 | if (user_mode(regs)) | |
243 | goto do_sigsegv; | |
244 | else { | |
245 | /* Synchronize this task's top level page-table | |
246 | with the "reference" page table from init. */ | |
247 | long index = pgd_index(address); | |
248 | pgd_t *pgd, *pgd_k; | |
249 | ||
250 | pgd = current->active_mm->pgd + index; | |
251 | pgd_k = swapper_pg_dir + index; | |
252 | if (!pgd_present(*pgd) && pgd_present(*pgd_k)) { | |
253 | pgd_val(*pgd) = pgd_val(*pgd_k); | |
254 | return; | |
255 | } | |
256 | goto no_context; | |
257 | } | |
258 | #endif | |
259 | } |