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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
61e85e36 JB |
2 | /* |
3 | * OpenRISC fault.c | |
4 | * | |
5 | * Linux architectural port borrowing liberally from similar works of | |
6 | * others. All original copyrights apply as per the original source | |
7 | * declaration. | |
8 | * | |
9 | * Modifications for the OpenRISC architecture: | |
10 | * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> | |
11 | * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> | |
61e85e36 JB |
12 | */ |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/interrupt.h> | |
ce139ab8 | 16 | #include <linux/extable.h> |
3f07c014 | 17 | #include <linux/sched/signal.h> |
61e85e36 | 18 | |
7c0f6ba6 | 19 | #include <linux/uaccess.h> |
61e85e36 JB |
20 | #include <asm/siginfo.h> |
21 | #include <asm/signal.h> | |
22 | ||
23 | #define NUM_TLB_ENTRIES 64 | |
24 | #define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1)) | |
25 | ||
26 | unsigned long pte_misses; /* updated by do_page_fault() */ | |
27 | unsigned long pte_errors; /* updated by do_page_fault() */ | |
28 | ||
29 | /* __PHX__ :: - check the vmalloc_fault in do_page_fault() | |
30 | * - also look into include/asm-or32/mmu_context.h | |
31 | */ | |
8e6d08e0 | 32 | volatile pgd_t *current_pgd[NR_CPUS]; |
61e85e36 JB |
33 | |
34 | extern void die(char *, struct pt_regs *, long); | |
35 | ||
36 | /* | |
37 | * This routine handles page faults. It determines the address, | |
38 | * and the problem, and then passes it off to one of the appropriate | |
39 | * routines. | |
40 | * | |
41 | * If this routine detects a bad access, it returns 1, otherwise it | |
42 | * returns 0. | |
43 | */ | |
44 | ||
45 | asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address, | |
46 | unsigned long vector, int write_acc) | |
47 | { | |
48 | struct task_struct *tsk; | |
49 | struct mm_struct *mm; | |
50 | struct vm_area_struct *vma; | |
75bfb9a1 | 51 | int si_code; |
50a7ca3c | 52 | vm_fault_t fault; |
4971f2bd | 53 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
61e85e36 JB |
54 | |
55 | tsk = current; | |
56 | ||
57 | /* | |
58 | * We fault-in kernel-space virtual memory on-demand. The | |
59 | * 'reference' page table is init_mm.pgd. | |
60 | * | |
61 | * NOTE! We MUST NOT take any locks for this case. We may | |
62 | * be in an interrupt or a critical region, and should | |
63 | * only copy the information from the master page table, | |
64 | * nothing more. | |
65 | * | |
66 | * NOTE2: This is done so that, when updating the vmalloc | |
67 | * mappings we don't have to walk all processes pgdirs and | |
68 | * add the high mappings all at once. Instead we do it as they | |
69 | * are used. However vmalloc'ed page entries have the PAGE_GLOBAL | |
70 | * bit set so sometimes the TLB can use a lingering entry. | |
71 | * | |
72 | * This verifies that the fault happens in kernel space | |
73 | * and that the fault was not a protection error. | |
74 | */ | |
75 | ||
76 | if (address >= VMALLOC_START && | |
77 | (vector != 0x300 && vector != 0x400) && | |
78 | !user_mode(regs)) | |
79 | goto vmalloc_fault; | |
80 | ||
81 | /* If exceptions were enabled, we can reenable them here */ | |
82 | if (user_mode(regs)) { | |
83 | /* Exception was in userspace: reenable interrupts */ | |
84 | local_irq_enable(); | |
759496ba | 85 | flags |= FAULT_FLAG_USER; |
61e85e36 JB |
86 | } else { |
87 | /* If exception was in a syscall, then IRQ's may have | |
88 | * been enabled or disabled. If they were enabled, | |
89 | * reenable them. | |
90 | */ | |
91 | if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE)) | |
92 | local_irq_enable(); | |
93 | } | |
94 | ||
95 | mm = tsk->mm; | |
75bfb9a1 | 96 | si_code = SEGV_MAPERR; |
61e85e36 JB |
97 | |
98 | /* | |
99 | * If we're in an interrupt or have no user | |
100 | * context, we must not take the fault.. | |
101 | */ | |
102 | ||
103 | if (in_interrupt() || !mm) | |
104 | goto no_context; | |
105 | ||
4971f2bd | 106 | retry: |
61e85e36 JB |
107 | down_read(&mm->mmap_sem); |
108 | vma = find_vma(mm, address); | |
109 | ||
110 | if (!vma) | |
111 | goto bad_area; | |
112 | ||
113 | if (vma->vm_start <= address) | |
114 | goto good_area; | |
115 | ||
116 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
117 | goto bad_area; | |
118 | ||
119 | if (user_mode(regs)) { | |
120 | /* | |
121 | * accessing the stack below usp is always a bug. | |
122 | * we get page-aligned addresses so we can only check | |
123 | * if we're within a page from usp, but that might be | |
124 | * enough to catch brutal errors at least. | |
125 | */ | |
126 | if (address + PAGE_SIZE < regs->sp) | |
127 | goto bad_area; | |
128 | } | |
129 | if (expand_stack(vma, address)) | |
130 | goto bad_area; | |
131 | ||
132 | /* | |
133 | * Ok, we have a good vm_area for this memory access, so | |
134 | * we can handle it.. | |
135 | */ | |
136 | ||
137 | good_area: | |
75bfb9a1 | 138 | si_code = SEGV_ACCERR; |
61e85e36 JB |
139 | |
140 | /* first do some preliminary protection checks */ | |
141 | ||
142 | if (write_acc) { | |
143 | if (!(vma->vm_flags & VM_WRITE)) | |
144 | goto bad_area; | |
4971f2bd | 145 | flags |= FAULT_FLAG_WRITE; |
61e85e36 JB |
146 | } else { |
147 | /* not present */ | |
148 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
149 | goto bad_area; | |
150 | } | |
151 | ||
152 | /* are we trying to execute nonexecutable area */ | |
153 | if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC)) | |
154 | goto bad_area; | |
155 | ||
156 | /* | |
157 | * If for any reason at all we couldn't handle the fault, | |
158 | * make sure we exit gracefully rather than endlessly redo | |
159 | * the fault. | |
160 | */ | |
161 | ||
dcddffd4 | 162 | fault = handle_mm_fault(vma, address, flags); |
4971f2bd KC |
163 | |
164 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
165 | return; | |
166 | ||
61e85e36 JB |
167 | if (unlikely(fault & VM_FAULT_ERROR)) { |
168 | if (fault & VM_FAULT_OOM) | |
169 | goto out_of_memory; | |
33692f27 LT |
170 | else if (fault & VM_FAULT_SIGSEGV) |
171 | goto bad_area; | |
61e85e36 JB |
172 | else if (fault & VM_FAULT_SIGBUS) |
173 | goto do_sigbus; | |
174 | BUG(); | |
175 | } | |
4971f2bd KC |
176 | |
177 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
178 | /*RGD modeled on Cris */ | |
179 | if (fault & VM_FAULT_MAJOR) | |
180 | tsk->maj_flt++; | |
181 | else | |
182 | tsk->min_flt++; | |
183 | if (fault & VM_FAULT_RETRY) { | |
184 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 185 | flags |= FAULT_FLAG_TRIED; |
4971f2bd KC |
186 | |
187 | /* No need to up_read(&mm->mmap_sem) as we would | |
188 | * have already released it in __lock_page_or_retry | |
189 | * in mm/filemap.c. | |
190 | */ | |
191 | ||
192 | goto retry; | |
193 | } | |
194 | } | |
61e85e36 JB |
195 | |
196 | up_read(&mm->mmap_sem); | |
197 | return; | |
198 | ||
199 | /* | |
200 | * Something tried to access memory that isn't in our memory map.. | |
201 | * Fix it, but check if it's kernel or user first.. | |
202 | */ | |
203 | ||
204 | bad_area: | |
205 | up_read(&mm->mmap_sem); | |
206 | ||
207 | bad_area_nosemaphore: | |
208 | ||
209 | /* User mode accesses just cause a SIGSEGV */ | |
210 | ||
211 | if (user_mode(regs)) { | |
75bfb9a1 | 212 | force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk); |
61e85e36 JB |
213 | return; |
214 | } | |
215 | ||
216 | no_context: | |
217 | ||
218 | /* Are we prepared to handle this kernel fault? | |
219 | * | |
220 | * (The kernel has valid exception-points in the source | |
221 | * when it acesses user-memory. When it fails in one | |
222 | * of those points, we find it in a table and do a jump | |
223 | * to some fixup code that loads an appropriate error | |
224 | * code) | |
225 | */ | |
226 | ||
227 | { | |
228 | const struct exception_table_entry *entry; | |
229 | ||
230 | __asm__ __volatile__("l.nop 42"); | |
231 | ||
232 | if ((entry = search_exception_tables(regs->pc)) != NULL) { | |
233 | /* Adjust the instruction pointer in the stackframe */ | |
234 | regs->pc = entry->fixup; | |
235 | return; | |
236 | } | |
237 | } | |
238 | ||
239 | /* | |
240 | * Oops. The kernel tried to access some bad page. We'll have to | |
241 | * terminate things with extreme prejudice. | |
242 | */ | |
243 | ||
244 | if ((unsigned long)(address) < PAGE_SIZE) | |
245 | printk(KERN_ALERT | |
246 | "Unable to handle kernel NULL pointer dereference"); | |
247 | else | |
248 | printk(KERN_ALERT "Unable to handle kernel access"); | |
249 | printk(" at virtual address 0x%08lx\n", address); | |
250 | ||
251 | die("Oops", regs, write_acc); | |
252 | ||
253 | do_exit(SIGKILL); | |
254 | ||
255 | /* | |
256 | * We ran out of memory, or some other thing happened to us that made | |
257 | * us unable to handle the page fault gracefully. | |
258 | */ | |
259 | ||
260 | out_of_memory: | |
261 | __asm__ __volatile__("l.nop 42"); | |
262 | __asm__ __volatile__("l.nop 1"); | |
263 | ||
264 | up_read(&mm->mmap_sem); | |
609838cf JW |
265 | if (!user_mode(regs)) |
266 | goto no_context; | |
267 | pagefault_out_of_memory(); | |
268 | return; | |
61e85e36 JB |
269 | |
270 | do_sigbus: | |
271 | up_read(&mm->mmap_sem); | |
272 | ||
273 | /* | |
274 | * Send a sigbus, regardless of whether we were in kernel | |
275 | * or user mode. | |
276 | */ | |
75bfb9a1 | 277 | force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk); |
61e85e36 JB |
278 | |
279 | /* Kernel mode? Handle exceptions or die */ | |
280 | if (!user_mode(regs)) | |
281 | goto no_context; | |
282 | return; | |
283 | ||
284 | vmalloc_fault: | |
285 | { | |
286 | /* | |
287 | * Synchronize this task's top level page-table | |
288 | * with the 'reference' page table. | |
289 | * | |
290 | * Use current_pgd instead of tsk->active_mm->pgd | |
291 | * since the latter might be unavailable if this | |
292 | * code is executed in a misfortunately run irq | |
293 | * (like inside schedule() between switch_mm and | |
294 | * switch_to...). | |
295 | */ | |
296 | ||
297 | int offset = pgd_index(address); | |
298 | pgd_t *pgd, *pgd_k; | |
299 | pud_t *pud, *pud_k; | |
300 | pmd_t *pmd, *pmd_k; | |
301 | pte_t *pte_k; | |
302 | ||
303 | /* | |
304 | phx_warn("do_page_fault(): vmalloc_fault will not work, " | |
305 | "since current_pgd assign a proper value somewhere\n" | |
306 | "anyhow we don't need this at the moment\n"); | |
307 | ||
308 | phx_mmu("vmalloc_fault"); | |
309 | */ | |
8e6d08e0 | 310 | pgd = (pgd_t *)current_pgd[smp_processor_id()] + offset; |
61e85e36 JB |
311 | pgd_k = init_mm.pgd + offset; |
312 | ||
313 | /* Since we're two-level, we don't need to do both | |
314 | * set_pgd and set_pmd (they do the same thing). If | |
315 | * we go three-level at some point, do the right thing | |
316 | * with pgd_present and set_pgd here. | |
317 | * | |
318 | * Also, since the vmalloc area is global, we don't | |
319 | * need to copy individual PTE's, it is enough to | |
320 | * copy the pgd pointer into the pte page of the | |
321 | * root task. If that is there, we'll find our pte if | |
322 | * it exists. | |
323 | */ | |
324 | ||
325 | pud = pud_offset(pgd, address); | |
326 | pud_k = pud_offset(pgd_k, address); | |
327 | if (!pud_present(*pud_k)) | |
328 | goto no_context; | |
329 | ||
330 | pmd = pmd_offset(pud, address); | |
331 | pmd_k = pmd_offset(pud_k, address); | |
332 | ||
333 | if (!pmd_present(*pmd_k)) | |
334 | goto bad_area_nosemaphore; | |
335 | ||
336 | set_pmd(pmd, *pmd_k); | |
337 | ||
338 | /* Make sure the actual PTE exists as well to | |
339 | * catch kernel vmalloc-area accesses to non-mapped | |
340 | * addresses. If we don't do this, this will just | |
341 | * silently loop forever. | |
342 | */ | |
343 | ||
344 | pte_k = pte_offset_kernel(pmd_k, address); | |
345 | if (!pte_present(*pte_k)) | |
346 | goto no_context; | |
347 | ||
348 | return; | |
349 | } | |
350 | } |