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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> | |
26 | ||
1da177e4 LT |
27 | #include <asm/uaccess.h> |
28 | ||
29 | extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *); | |
30 | ||
31 | ||
32 | /* | |
33 | * Force a new ASN for a task. | |
34 | */ | |
35 | ||
36 | #ifndef CONFIG_SMP | |
37 | unsigned long last_asn = ASN_FIRST_VERSION; | |
38 | #endif | |
39 | ||
40 | void | |
41 | __load_new_mm_context(struct mm_struct *next_mm) | |
42 | { | |
43 | unsigned long mmc; | |
44 | struct pcb_struct *pcb; | |
45 | ||
46 | mmc = __get_new_mm_context(next_mm, smp_processor_id()); | |
47 | next_mm->context[smp_processor_id()] = mmc; | |
48 | ||
49 | pcb = ¤t_thread_info()->pcb; | |
50 | pcb->asn = mmc & HARDWARE_ASN_MASK; | |
51 | pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; | |
52 | ||
53 | __reload_thread(pcb); | |
54 | } | |
55 | ||
56 | ||
57 | /* | |
58 | * This routine handles page faults. It determines the address, | |
59 | * and the problem, and then passes it off to handle_mm_fault(). | |
60 | * | |
61 | * mmcsr: | |
62 | * 0 = translation not valid | |
63 | * 1 = access violation | |
64 | * 2 = fault-on-read | |
65 | * 3 = fault-on-execute | |
66 | * 4 = fault-on-write | |
67 | * | |
68 | * cause: | |
69 | * -1 = instruction fetch | |
70 | * 0 = load | |
71 | * 1 = store | |
72 | * | |
73 | * Registers $9 through $15 are saved in a block just prior to `regs' and | |
74 | * are saved and restored around the call to allow exception code to | |
75 | * modify them. | |
76 | */ | |
77 | ||
78 | /* Macro for exception fixup code to access integer registers. */ | |
79 | #define dpf_reg(r) \ | |
80 | (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \ | |
81 | (r) <= 18 ? (r)+8 : (r)-10]) | |
82 | ||
83 | asmlinkage void | |
84 | do_page_fault(unsigned long address, unsigned long mmcsr, | |
85 | long cause, struct pt_regs *regs) | |
86 | { | |
87 | struct vm_area_struct * vma; | |
88 | struct mm_struct *mm = current->mm; | |
89 | const struct exception_table_entry *fixup; | |
90 | int fault, si_code = SEGV_MAPERR; | |
91 | siginfo_t info; | |
759496ba | 92 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
1da177e4 LT |
93 | |
94 | /* As of EV6, a load into $31/$f31 is a prefetch, and never faults | |
95 | (or is suppressed by the PALcode). Support that for older CPUs | |
96 | by ignoring such an instruction. */ | |
97 | if (cause == 0) { | |
98 | unsigned int insn; | |
99 | __get_user(insn, (unsigned int __user *)regs->pc); | |
100 | if ((insn >> 21 & 0x1f) == 0x1f && | |
101 | /* ldq ldl ldt lds ldg ldf ldwu ldbu */ | |
102 | (1ul << (insn >> 26) & 0x30f00001400ul)) { | |
103 | regs->pc += 4; | |
104 | return; | |
105 | } | |
106 | } | |
107 | ||
108 | /* If we're in an interrupt context, or have no user context, | |
109 | we must not take the fault. */ | |
6edaf68a | 110 | if (!mm || in_atomic()) |
1da177e4 LT |
111 | goto no_context; |
112 | ||
113 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
114 | if (address >= TASK_SIZE) | |
115 | goto vmalloc_fault; | |
116 | #endif | |
759496ba JW |
117 | if (user_mode(regs)) |
118 | flags |= FAULT_FLAG_USER; | |
0bcc426b | 119 | retry: |
1da177e4 LT |
120 | down_read(&mm->mmap_sem); |
121 | vma = find_vma(mm, address); | |
122 | if (!vma) | |
123 | goto bad_area; | |
124 | if (vma->vm_start <= address) | |
125 | goto good_area; | |
126 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
127 | goto bad_area; | |
128 | if (expand_stack(vma, address)) | |
129 | goto bad_area; | |
130 | ||
131 | /* Ok, we have a good vm_area for this memory access, so | |
132 | we can handle it. */ | |
133 | good_area: | |
134 | si_code = SEGV_ACCERR; | |
135 | if (cause < 0) { | |
136 | if (!(vma->vm_flags & VM_EXEC)) | |
137 | goto bad_area; | |
138 | } else if (!cause) { | |
139 | /* Allow reads even for write-only mappings */ | |
140 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) | |
141 | goto bad_area; | |
142 | } else { | |
143 | if (!(vma->vm_flags & VM_WRITE)) | |
144 | goto bad_area; | |
759496ba | 145 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
146 | } |
147 | ||
1da177e4 LT |
148 | /* If for any reason at all we couldn't handle the fault, |
149 | make sure we exit gracefully rather than endlessly redo | |
150 | the fault. */ | |
0bcc426b KC |
151 | fault = handle_mm_fault(mm, vma, address, flags); |
152 | ||
153 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
154 | return; | |
155 | ||
83c54070 NP |
156 | if (unlikely(fault & VM_FAULT_ERROR)) { |
157 | if (fault & VM_FAULT_OOM) | |
158 | goto out_of_memory; | |
159 | else if (fault & VM_FAULT_SIGBUS) | |
160 | goto do_sigbus; | |
1da177e4 LT |
161 | BUG(); |
162 | } | |
0bcc426b KC |
163 | |
164 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
165 | if (fault & VM_FAULT_MAJOR) | |
166 | current->maj_flt++; | |
167 | else | |
168 | current->min_flt++; | |
169 | if (fault & VM_FAULT_RETRY) { | |
170 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
171 | ||
172 | /* No need to up_read(&mm->mmap_sem) as we would | |
173 | * have already released it in __lock_page_or_retry | |
174 | * in mm/filemap.c. | |
175 | */ | |
176 | ||
177 | goto retry; | |
178 | } | |
179 | } | |
180 | ||
181 | up_read(&mm->mmap_sem); | |
182 | ||
1da177e4 LT |
183 | return; |
184 | ||
185 | /* Something tried to access memory that isn't in our memory map. | |
186 | Fix it, but check if it's kernel or user first. */ | |
187 | bad_area: | |
188 | up_read(&mm->mmap_sem); | |
189 | ||
190 | if (user_mode(regs)) | |
191 | goto do_sigsegv; | |
192 | ||
193 | no_context: | |
194 | /* Are we prepared to handle this fault as an exception? */ | |
195 | if ((fixup = search_exception_tables(regs->pc)) != 0) { | |
196 | unsigned long newpc; | |
197 | newpc = fixup_exception(dpf_reg, fixup, regs->pc); | |
198 | regs->pc = newpc; | |
199 | return; | |
200 | } | |
201 | ||
202 | /* Oops. The kernel tried to access some bad page. We'll have to | |
203 | terminate things with extreme prejudice. */ | |
204 | printk(KERN_ALERT "Unable to handle kernel paging request at " | |
205 | "virtual address %016lx\n", address); | |
206 | die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16); | |
207 | do_exit(SIGKILL); | |
208 | ||
209 | /* We ran out of memory, or some other thing happened to us that | |
210 | made us unable to handle the page fault gracefully. */ | |
211 | out_of_memory: | |
0bcc426b | 212 | up_read(&mm->mmap_sem); |
1da177e4 LT |
213 | if (!user_mode(regs)) |
214 | goto no_context; | |
1cb3d8e2 NP |
215 | pagefault_out_of_memory(); |
216 | return; | |
1da177e4 LT |
217 | |
218 | do_sigbus: | |
0bcc426b | 219 | up_read(&mm->mmap_sem); |
1da177e4 LT |
220 | /* Send a sigbus, regardless of whether we were in kernel |
221 | or user mode. */ | |
222 | info.si_signo = SIGBUS; | |
223 | info.si_errno = 0; | |
224 | info.si_code = BUS_ADRERR; | |
225 | info.si_addr = (void __user *) address; | |
226 | force_sig_info(SIGBUS, &info, current); | |
227 | if (!user_mode(regs)) | |
228 | goto no_context; | |
229 | return; | |
230 | ||
231 | do_sigsegv: | |
232 | info.si_signo = SIGSEGV; | |
233 | info.si_errno = 0; | |
234 | info.si_code = si_code; | |
235 | info.si_addr = (void __user *) address; | |
236 | force_sig_info(SIGSEGV, &info, current); | |
237 | return; | |
238 | ||
239 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
240 | vmalloc_fault: | |
241 | if (user_mode(regs)) | |
242 | goto do_sigsegv; | |
243 | else { | |
244 | /* Synchronize this task's top level page-table | |
245 | with the "reference" page table from init. */ | |
246 | long index = pgd_index(address); | |
247 | pgd_t *pgd, *pgd_k; | |
248 | ||
249 | pgd = current->active_mm->pgd + index; | |
250 | pgd_k = swapper_pg_dir + index; | |
251 | if (!pgd_present(*pgd) && pgd_present(*pgd_k)) { | |
252 | pgd_val(*pgd) = pgd_val(*pgd_k); | |
253 | return; | |
254 | } | |
255 | goto no_context; | |
256 | } | |
257 | #endif | |
258 | } |