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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/arch/alpha/mm/fault.c | |
4 | * | |
5 | * Copyright (C) 1995 Linus Torvalds | |
6 | */ | |
7 | ||
3f07c014 | 8 | #include <linux/sched/signal.h> |
1da177e4 LT |
9 | #include <linux/kernel.h> |
10 | #include <linux/mm.h> | |
11 | #include <asm/io.h> | |
12 | ||
13 | #define __EXTERN_INLINE inline | |
14 | #include <asm/mmu_context.h> | |
15 | #include <asm/tlbflush.h> | |
16 | #undef __EXTERN_INLINE | |
17 | ||
18 | #include <linux/signal.h> | |
19 | #include <linux/errno.h> | |
20 | #include <linux/string.h> | |
21 | #include <linux/types.h> | |
22 | #include <linux/ptrace.h> | |
23 | #include <linux/mman.h> | |
24 | #include <linux/smp.h> | |
1da177e4 | 25 | #include <linux/interrupt.h> |
9c14f835 | 26 | #include <linux/extable.h> |
70ffdb93 | 27 | #include <linux/uaccess.h> |
c0f6eda4 | 28 | #include <linux/perf_event.h> |
1da177e4 LT |
29 | |
30 | extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *); | |
31 | ||
32 | ||
33 | /* | |
34 | * Force a new ASN for a task. | |
35 | */ | |
36 | ||
37 | #ifndef CONFIG_SMP | |
38 | unsigned long last_asn = ASN_FIRST_VERSION; | |
39 | #endif | |
40 | ||
41 | void | |
42 | __load_new_mm_context(struct mm_struct *next_mm) | |
43 | { | |
44 | unsigned long mmc; | |
45 | struct pcb_struct *pcb; | |
46 | ||
47 | mmc = __get_new_mm_context(next_mm, smp_processor_id()); | |
48 | next_mm->context[smp_processor_id()] = mmc; | |
49 | ||
50 | pcb = ¤t_thread_info()->pcb; | |
51 | pcb->asn = mmc & HARDWARE_ASN_MASK; | |
52 | pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; | |
53 | ||
54 | __reload_thread(pcb); | |
55 | } | |
56 | ||
57 | ||
58 | /* | |
59 | * This routine handles page faults. It determines the address, | |
60 | * and the problem, and then passes it off to handle_mm_fault(). | |
61 | * | |
62 | * mmcsr: | |
63 | * 0 = translation not valid | |
64 | * 1 = access violation | |
65 | * 2 = fault-on-read | |
66 | * 3 = fault-on-execute | |
67 | * 4 = fault-on-write | |
68 | * | |
69 | * cause: | |
70 | * -1 = instruction fetch | |
71 | * 0 = load | |
72 | * 1 = store | |
73 | * | |
74 | * Registers $9 through $15 are saved in a block just prior to `regs' and | |
75 | * are saved and restored around the call to allow exception code to | |
76 | * modify them. | |
77 | */ | |
78 | ||
79 | /* Macro for exception fixup code to access integer registers. */ | |
80 | #define dpf_reg(r) \ | |
81 | (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \ | |
491af60f | 82 | (r) <= 18 ? (r)+10 : (r)-10]) |
1da177e4 LT |
83 | |
84 | asmlinkage void | |
85 | do_page_fault(unsigned long address, unsigned long mmcsr, | |
86 | long cause, struct pt_regs *regs) | |
87 | { | |
88 | struct vm_area_struct * vma; | |
89 | struct mm_struct *mm = current->mm; | |
90 | const struct exception_table_entry *fixup; | |
50a7ca3c SJ |
91 | int si_code = SEGV_MAPERR; |
92 | vm_fault_t fault; | |
dde16072 | 93 | unsigned int flags = FAULT_FLAG_DEFAULT; |
1da177e4 LT |
94 | |
95 | /* As of EV6, a load into $31/$f31 is a prefetch, and never faults | |
96 | (or is suppressed by the PALcode). Support that for older CPUs | |
97 | by ignoring such an instruction. */ | |
98 | if (cause == 0) { | |
99 | unsigned int insn; | |
100 | __get_user(insn, (unsigned int __user *)regs->pc); | |
101 | if ((insn >> 21 & 0x1f) == 0x1f && | |
102 | /* ldq ldl ldt lds ldg ldf ldwu ldbu */ | |
103 | (1ul << (insn >> 26) & 0x30f00001400ul)) { | |
104 | regs->pc += 4; | |
105 | return; | |
106 | } | |
107 | } | |
108 | ||
109 | /* If we're in an interrupt context, or have no user context, | |
110 | we must not take the fault. */ | |
70ffdb93 | 111 | if (!mm || faulthandler_disabled()) |
1da177e4 LT |
112 | goto no_context; |
113 | ||
114 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
115 | if (address >= TASK_SIZE) | |
116 | goto vmalloc_fault; | |
117 | #endif | |
759496ba JW |
118 | if (user_mode(regs)) |
119 | flags |= FAULT_FLAG_USER; | |
c0f6eda4 | 120 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
0bcc426b | 121 | retry: |
d8ed45c5 | 122 | mmap_read_lock(mm); |
1da177e4 LT |
123 | vma = find_vma(mm, address); |
124 | if (!vma) | |
125 | goto bad_area; | |
126 | if (vma->vm_start <= address) | |
127 | goto good_area; | |
128 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
129 | goto bad_area; | |
130 | if (expand_stack(vma, address)) | |
131 | goto bad_area; | |
132 | ||
133 | /* Ok, we have a good vm_area for this memory access, so | |
134 | we can handle it. */ | |
135 | good_area: | |
136 | si_code = SEGV_ACCERR; | |
137 | if (cause < 0) { | |
138 | if (!(vma->vm_flags & VM_EXEC)) | |
139 | goto bad_area; | |
140 | } else if (!cause) { | |
141 | /* Allow reads even for write-only mappings */ | |
142 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) | |
143 | goto bad_area; | |
144 | } else { | |
145 | if (!(vma->vm_flags & VM_WRITE)) | |
146 | goto bad_area; | |
759496ba | 147 | flags |= FAULT_FLAG_WRITE; |
1da177e4 LT |
148 | } |
149 | ||
1da177e4 LT |
150 | /* If for any reason at all we couldn't handle the fault, |
151 | make sure we exit gracefully rather than endlessly redo | |
152 | the fault. */ | |
c0f6eda4 | 153 | fault = handle_mm_fault(vma, address, flags, regs); |
0bcc426b | 154 | |
4ef87322 | 155 | if (fault_signal_pending(fault, regs)) |
0bcc426b KC |
156 | return; |
157 | ||
83c54070 NP |
158 | if (unlikely(fault & VM_FAULT_ERROR)) { |
159 | if (fault & VM_FAULT_OOM) | |
160 | goto out_of_memory; | |
33692f27 LT |
161 | else if (fault & VM_FAULT_SIGSEGV) |
162 | goto bad_area; | |
83c54070 NP |
163 | else if (fault & VM_FAULT_SIGBUS) |
164 | goto do_sigbus; | |
1da177e4 LT |
165 | BUG(); |
166 | } | |
0bcc426b KC |
167 | |
168 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
0bcc426b | 169 | if (fault & VM_FAULT_RETRY) { |
4064b982 | 170 | flags |= FAULT_FLAG_TRIED; |
0bcc426b | 171 | |
3e4e28c5 | 172 | /* No need to mmap_read_unlock(mm) as we would |
0bcc426b KC |
173 | * have already released it in __lock_page_or_retry |
174 | * in mm/filemap.c. | |
175 | */ | |
176 | ||
177 | goto retry; | |
178 | } | |
179 | } | |
180 | ||
d8ed45c5 | 181 | mmap_read_unlock(mm); |
0bcc426b | 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: | |
d8ed45c5 | 188 | mmap_read_unlock(mm); |
1da177e4 LT |
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: | |
d8ed45c5 | 212 | mmap_read_unlock(mm); |
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: | |
d8ed45c5 | 219 | mmap_read_unlock(mm); |
1da177e4 LT |
220 | /* Send a sigbus, regardless of whether we were in kernel |
221 | or user mode. */ | |
7de5f68d | 222 | force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address); |
1da177e4 LT |
223 | if (!user_mode(regs)) |
224 | goto no_context; | |
225 | return; | |
226 | ||
227 | do_sigsegv: | |
7de5f68d | 228 | force_sig_fault(SIGSEGV, si_code, (void __user *) address); |
1da177e4 LT |
229 | return; |
230 | ||
231 | #ifdef CONFIG_ALPHA_LARGE_VMALLOC | |
232 | vmalloc_fault: | |
233 | if (user_mode(regs)) | |
234 | goto do_sigsegv; | |
235 | else { | |
236 | /* Synchronize this task's top level page-table | |
237 | with the "reference" page table from init. */ | |
238 | long index = pgd_index(address); | |
239 | pgd_t *pgd, *pgd_k; | |
240 | ||
241 | pgd = current->active_mm->pgd + index; | |
242 | pgd_k = swapper_pg_dir + index; | |
243 | if (!pgd_present(*pgd) && pgd_present(*pgd_k)) { | |
244 | pgd_val(*pgd) = pgd_val(*pgd_k); | |
245 | return; | |
246 | } | |
247 | goto no_context; | |
248 | } | |
249 | #endif | |
250 | } |