xref: /linux/arch/um/kernel/tlb.c (revision 2697b79a469b68e3ad3640f55284359c1396278d) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <linux/mm.h>
7 #include <linux/module.h>
8 #include <linux/sched/signal.h>
9 
10 #include <asm/tlbflush.h>
11 #include <asm/mmu_context.h>
12 #include <as-layout.h>
13 #include <mem_user.h>
14 #include <os.h>
15 #include <skas.h>
16 #include <kern_util.h>
17 
18 struct host_vm_change {
19 	struct host_vm_op {
20 		enum { NONE, MMAP, MUNMAP, MPROTECT } type;
21 		union {
22 			struct {
23 				unsigned long addr;
24 				unsigned long len;
25 				unsigned int prot;
26 				int fd;
27 				__u64 offset;
28 			} mmap;
29 			struct {
30 				unsigned long addr;
31 				unsigned long len;
32 			} munmap;
33 			struct {
34 				unsigned long addr;
35 				unsigned long len;
36 				unsigned int prot;
37 			} mprotect;
38 		} u;
39 	} ops[1];
40 	int userspace;
41 	int index;
42 	struct mm_struct *mm;
43 	void *data;
44 	int force;
45 };
46 
47 #define INIT_HVC(mm, force, userspace) \
48 	((struct host_vm_change) \
49 	 { .ops		= { { .type = NONE } },	\
50 	   .mm		= mm, \
51        	   .data	= NULL, \
52 	   .userspace	= userspace, \
53 	   .index	= 0, \
54 	   .force	= force })
55 
56 static void report_enomem(void)
57 {
58 	printk(KERN_ERR "UML ran out of memory on the host side! "
59 			"This can happen due to a memory limitation or "
60 			"vm.max_map_count has been reached.\n");
61 }
62 
63 static int do_ops(struct host_vm_change *hvc, int end,
64 		  int finished)
65 {
66 	struct host_vm_op *op;
67 	int i, ret = 0;
68 
69 	for (i = 0; i < end && !ret; i++) {
70 		op = &hvc->ops[i];
71 		switch (op->type) {
72 		case MMAP:
73 			if (hvc->userspace)
74 				ret = map(&hvc->mm->context.id, op->u.mmap.addr,
75 					  op->u.mmap.len, op->u.mmap.prot,
76 					  op->u.mmap.fd,
77 					  op->u.mmap.offset, finished,
78 					  &hvc->data);
79 			else
80 				map_memory(op->u.mmap.addr, op->u.mmap.offset,
81 					   op->u.mmap.len, 1, 1, 1);
82 			break;
83 		case MUNMAP:
84 			if (hvc->userspace)
85 				ret = unmap(&hvc->mm->context.id,
86 					    op->u.munmap.addr,
87 					    op->u.munmap.len, finished,
88 					    &hvc->data);
89 			else
90 				ret = os_unmap_memory(
91 					(void *) op->u.munmap.addr,
92 						      op->u.munmap.len);
93 
94 			break;
95 		case MPROTECT:
96 			if (hvc->userspace)
97 				ret = protect(&hvc->mm->context.id,
98 					      op->u.mprotect.addr,
99 					      op->u.mprotect.len,
100 					      op->u.mprotect.prot,
101 					      finished, &hvc->data);
102 			else
103 				ret = os_protect_memory(
104 					(void *) op->u.mprotect.addr,
105 							op->u.mprotect.len,
106 							1, 1, 1);
107 			break;
108 		default:
109 			printk(KERN_ERR "Unknown op type %d in do_ops\n",
110 			       op->type);
111 			BUG();
112 			break;
113 		}
114 	}
115 
116 	if (ret == -ENOMEM)
117 		report_enomem();
118 
119 	return ret;
120 }
121 
122 static int add_mmap(unsigned long virt, unsigned long phys, unsigned long len,
123 		    unsigned int prot, struct host_vm_change *hvc)
124 {
125 	__u64 offset;
126 	struct host_vm_op *last;
127 	int fd = -1, ret = 0;
128 
129 	if (hvc->userspace)
130 		fd = phys_mapping(phys, &offset);
131 	else
132 		offset = phys;
133 	if (hvc->index != 0) {
134 		last = &hvc->ops[hvc->index - 1];
135 		if ((last->type == MMAP) &&
136 		   (last->u.mmap.addr + last->u.mmap.len == virt) &&
137 		   (last->u.mmap.prot == prot) && (last->u.mmap.fd == fd) &&
138 		   (last->u.mmap.offset + last->u.mmap.len == offset)) {
139 			last->u.mmap.len += len;
140 			return 0;
141 		}
142 	}
143 
144 	if (hvc->index == ARRAY_SIZE(hvc->ops)) {
145 		ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
146 		hvc->index = 0;
147 	}
148 
149 	hvc->ops[hvc->index++] = ((struct host_vm_op)
150 				  { .type	= MMAP,
151 				    .u = { .mmap = { .addr	= virt,
152 						     .len	= len,
153 						     .prot	= prot,
154 						     .fd	= fd,
155 						     .offset	= offset }
156 			   } });
157 	return ret;
158 }
159 
160 static int add_munmap(unsigned long addr, unsigned long len,
161 		      struct host_vm_change *hvc)
162 {
163 	struct host_vm_op *last;
164 	int ret = 0;
165 
166 	if (hvc->index != 0) {
167 		last = &hvc->ops[hvc->index - 1];
168 		if ((last->type == MUNMAP) &&
169 		   (last->u.munmap.addr + last->u.mmap.len == addr)) {
170 			last->u.munmap.len += len;
171 			return 0;
172 		}
173 	}
174 
175 	if (hvc->index == ARRAY_SIZE(hvc->ops)) {
176 		ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
177 		hvc->index = 0;
178 	}
179 
180 	hvc->ops[hvc->index++] = ((struct host_vm_op)
181 				  { .type	= MUNMAP,
182 			     	    .u = { .munmap = { .addr	= addr,
183 						       .len	= len } } });
184 	return ret;
185 }
186 
187 static int add_mprotect(unsigned long addr, unsigned long len,
188 			unsigned int prot, struct host_vm_change *hvc)
189 {
190 	struct host_vm_op *last;
191 	int ret = 0;
192 
193 	if (hvc->index != 0) {
194 		last = &hvc->ops[hvc->index - 1];
195 		if ((last->type == MPROTECT) &&
196 		   (last->u.mprotect.addr + last->u.mprotect.len == addr) &&
197 		   (last->u.mprotect.prot == prot)) {
198 			last->u.mprotect.len += len;
199 			return 0;
200 		}
201 	}
202 
203 	if (hvc->index == ARRAY_SIZE(hvc->ops)) {
204 		ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
205 		hvc->index = 0;
206 	}
207 
208 	hvc->ops[hvc->index++] = ((struct host_vm_op)
209 				  { .type	= MPROTECT,
210 			     	    .u = { .mprotect = { .addr	= addr,
211 							 .len	= len,
212 							 .prot	= prot } } });
213 	return ret;
214 }
215 
216 #define ADD_ROUND(n, inc) (((n) + (inc)) & ~((inc) - 1))
217 
218 static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
219 				   unsigned long end,
220 				   struct host_vm_change *hvc)
221 {
222 	pte_t *pte;
223 	int r, w, x, prot, ret = 0;
224 
225 	pte = pte_offset_kernel(pmd, addr);
226 	do {
227 		r = pte_read(*pte);
228 		w = pte_write(*pte);
229 		x = pte_exec(*pte);
230 		if (!pte_young(*pte)) {
231 			r = 0;
232 			w = 0;
233 		} else if (!pte_dirty(*pte))
234 			w = 0;
235 
236 		prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
237 			(x ? UM_PROT_EXEC : 0));
238 		if (hvc->force || pte_newpage(*pte)) {
239 			if (pte_present(*pte)) {
240 				if (pte_newpage(*pte))
241 					ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
242 						       PAGE_SIZE, prot, hvc);
243 			} else
244 				ret = add_munmap(addr, PAGE_SIZE, hvc);
245 		} else if (pte_newprot(*pte))
246 			ret = add_mprotect(addr, PAGE_SIZE, prot, hvc);
247 		*pte = pte_mkuptodate(*pte);
248 	} while (pte++, addr += PAGE_SIZE, ((addr < end) && !ret));
249 	return ret;
250 }
251 
252 static inline int update_pmd_range(pud_t *pud, unsigned long addr,
253 				   unsigned long end,
254 				   struct host_vm_change *hvc)
255 {
256 	pmd_t *pmd;
257 	unsigned long next;
258 	int ret = 0;
259 
260 	pmd = pmd_offset(pud, addr);
261 	do {
262 		next = pmd_addr_end(addr, end);
263 		if (!pmd_present(*pmd)) {
264 			if (hvc->force || pmd_newpage(*pmd)) {
265 				ret = add_munmap(addr, next - addr, hvc);
266 				pmd_mkuptodate(*pmd);
267 			}
268 		}
269 		else ret = update_pte_range(pmd, addr, next, hvc);
270 	} while (pmd++, addr = next, ((addr < end) && !ret));
271 	return ret;
272 }
273 
274 static inline int update_pud_range(p4d_t *p4d, unsigned long addr,
275 				   unsigned long end,
276 				   struct host_vm_change *hvc)
277 {
278 	pud_t *pud;
279 	unsigned long next;
280 	int ret = 0;
281 
282 	pud = pud_offset(p4d, addr);
283 	do {
284 		next = pud_addr_end(addr, end);
285 		if (!pud_present(*pud)) {
286 			if (hvc->force || pud_newpage(*pud)) {
287 				ret = add_munmap(addr, next - addr, hvc);
288 				pud_mkuptodate(*pud);
289 			}
290 		}
291 		else ret = update_pmd_range(pud, addr, next, hvc);
292 	} while (pud++, addr = next, ((addr < end) && !ret));
293 	return ret;
294 }
295 
296 static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
297 				   unsigned long end,
298 				   struct host_vm_change *hvc)
299 {
300 	p4d_t *p4d;
301 	unsigned long next;
302 	int ret = 0;
303 
304 	p4d = p4d_offset(pgd, addr);
305 	do {
306 		next = p4d_addr_end(addr, end);
307 		if (!p4d_present(*p4d)) {
308 			if (hvc->force || p4d_newpage(*p4d)) {
309 				ret = add_munmap(addr, next - addr, hvc);
310 				p4d_mkuptodate(*p4d);
311 			}
312 		} else
313 			ret = update_pud_range(p4d, addr, next, hvc);
314 	} while (p4d++, addr = next, ((addr < end) && !ret));
315 	return ret;
316 }
317 
318 static void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
319 			     unsigned long end_addr, int force)
320 {
321 	pgd_t *pgd;
322 	struct host_vm_change hvc;
323 	unsigned long addr = start_addr, next;
324 	int ret = 0, userspace = 1;
325 
326 	hvc = INIT_HVC(mm, force, userspace);
327 	pgd = pgd_offset(mm, addr);
328 	do {
329 		next = pgd_addr_end(addr, end_addr);
330 		if (!pgd_present(*pgd)) {
331 			if (force || pgd_newpage(*pgd)) {
332 				ret = add_munmap(addr, next - addr, &hvc);
333 				pgd_mkuptodate(*pgd);
334 			}
335 		} else
336 			ret = update_p4d_range(pgd, addr, next, &hvc);
337 	} while (pgd++, addr = next, ((addr < end_addr) && !ret));
338 
339 	if (!ret)
340 		ret = do_ops(&hvc, hvc.index, 1);
341 
342 	/* This is not an else because ret is modified above */
343 	if (ret) {
344 		struct mm_id *mm_idp = &current->mm->context.id;
345 
346 		printk(KERN_ERR "fix_range_common: failed, killing current "
347 		       "process: %d\n", task_tgid_vnr(current));
348 		mm_idp->kill = 1;
349 	}
350 }
351 
352 static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
353 {
354 	struct mm_struct *mm;
355 	pgd_t *pgd;
356 	p4d_t *p4d;
357 	pud_t *pud;
358 	pmd_t *pmd;
359 	pte_t *pte;
360 	unsigned long addr, last;
361 	int updated = 0, err = 0, force = 0, userspace = 0;
362 	struct host_vm_change hvc;
363 
364 	mm = &init_mm;
365 	hvc = INIT_HVC(mm, force, userspace);
366 	for (addr = start; addr < end;) {
367 		pgd = pgd_offset(mm, addr);
368 		if (!pgd_present(*pgd)) {
369 			last = ADD_ROUND(addr, PGDIR_SIZE);
370 			if (last > end)
371 				last = end;
372 			if (pgd_newpage(*pgd)) {
373 				updated = 1;
374 				err = add_munmap(addr, last - addr, &hvc);
375 				if (err < 0)
376 					panic("munmap failed, errno = %d\n",
377 					      -err);
378 			}
379 			addr = last;
380 			continue;
381 		}
382 
383 		p4d = p4d_offset(pgd, addr);
384 		if (!p4d_present(*p4d)) {
385 			last = ADD_ROUND(addr, P4D_SIZE);
386 			if (last > end)
387 				last = end;
388 			if (p4d_newpage(*p4d)) {
389 				updated = 1;
390 				err = add_munmap(addr, last - addr, &hvc);
391 				if (err < 0)
392 					panic("munmap failed, errno = %d\n",
393 					      -err);
394 			}
395 			addr = last;
396 			continue;
397 		}
398 
399 		pud = pud_offset(p4d, addr);
400 		if (!pud_present(*pud)) {
401 			last = ADD_ROUND(addr, PUD_SIZE);
402 			if (last > end)
403 				last = end;
404 			if (pud_newpage(*pud)) {
405 				updated = 1;
406 				err = add_munmap(addr, last - addr, &hvc);
407 				if (err < 0)
408 					panic("munmap failed, errno = %d\n",
409 					      -err);
410 			}
411 			addr = last;
412 			continue;
413 		}
414 
415 		pmd = pmd_offset(pud, addr);
416 		if (!pmd_present(*pmd)) {
417 			last = ADD_ROUND(addr, PMD_SIZE);
418 			if (last > end)
419 				last = end;
420 			if (pmd_newpage(*pmd)) {
421 				updated = 1;
422 				err = add_munmap(addr, last - addr, &hvc);
423 				if (err < 0)
424 					panic("munmap failed, errno = %d\n",
425 					      -err);
426 			}
427 			addr = last;
428 			continue;
429 		}
430 
431 		pte = pte_offset_kernel(pmd, addr);
432 		if (!pte_present(*pte) || pte_newpage(*pte)) {
433 			updated = 1;
434 			err = add_munmap(addr, PAGE_SIZE, &hvc);
435 			if (err < 0)
436 				panic("munmap failed, errno = %d\n",
437 				      -err);
438 			if (pte_present(*pte))
439 				err = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
440 					       PAGE_SIZE, 0, &hvc);
441 		}
442 		else if (pte_newprot(*pte)) {
443 			updated = 1;
444 			err = add_mprotect(addr, PAGE_SIZE, 0, &hvc);
445 		}
446 		addr += PAGE_SIZE;
447 	}
448 	if (!err)
449 		err = do_ops(&hvc, hvc.index, 1);
450 
451 	if (err < 0)
452 		panic("flush_tlb_kernel failed, errno = %d\n", err);
453 	return updated;
454 }
455 
456 void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
457 {
458 	pgd_t *pgd;
459 	p4d_t *p4d;
460 	pud_t *pud;
461 	pmd_t *pmd;
462 	pte_t *pte;
463 	struct mm_struct *mm = vma->vm_mm;
464 	void *flush = NULL;
465 	int r, w, x, prot, err = 0;
466 	struct mm_id *mm_id;
467 
468 	address &= PAGE_MASK;
469 
470 	pgd = pgd_offset(mm, address);
471 	if (!pgd_present(*pgd))
472 		goto kill;
473 
474 	p4d = p4d_offset(pgd, address);
475 	if (!p4d_present(*p4d))
476 		goto kill;
477 
478 	pud = pud_offset(p4d, address);
479 	if (!pud_present(*pud))
480 		goto kill;
481 
482 	pmd = pmd_offset(pud, address);
483 	if (!pmd_present(*pmd))
484 		goto kill;
485 
486 	pte = pte_offset_kernel(pmd, address);
487 
488 	r = pte_read(*pte);
489 	w = pte_write(*pte);
490 	x = pte_exec(*pte);
491 	if (!pte_young(*pte)) {
492 		r = 0;
493 		w = 0;
494 	} else if (!pte_dirty(*pte)) {
495 		w = 0;
496 	}
497 
498 	mm_id = &mm->context.id;
499 	prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
500 		(x ? UM_PROT_EXEC : 0));
501 	if (pte_newpage(*pte)) {
502 		if (pte_present(*pte)) {
503 			unsigned long long offset;
504 			int fd;
505 
506 			fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
507 			err = map(mm_id, address, PAGE_SIZE, prot, fd, offset,
508 				  1, &flush);
509 		}
510 		else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
511 	}
512 	else if (pte_newprot(*pte))
513 		err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
514 
515 	if (err) {
516 		if (err == -ENOMEM)
517 			report_enomem();
518 
519 		goto kill;
520 	}
521 
522 	*pte = pte_mkuptodate(*pte);
523 
524 	return;
525 
526 kill:
527 	printk(KERN_ERR "Failed to flush page for address 0x%lx\n", address);
528 	force_sig(SIGKILL);
529 }
530 
531 void flush_tlb_all(void)
532 {
533 	/*
534 	 * Don't bother flushing if this address space is about to be
535 	 * destroyed.
536 	 */
537 	if (atomic_read(&current->mm->mm_users) == 0)
538 		return;
539 
540 	flush_tlb_mm(current->mm);
541 }
542 
543 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
544 {
545 	flush_tlb_kernel_range_common(start, end);
546 }
547 
548 void flush_tlb_kernel_vm(void)
549 {
550 	flush_tlb_kernel_range_common(start_vm, end_vm);
551 }
552 
553 void __flush_tlb_one(unsigned long addr)
554 {
555 	flush_tlb_kernel_range_common(addr, addr + PAGE_SIZE);
556 }
557 
558 static void fix_range(struct mm_struct *mm, unsigned long start_addr,
559 		      unsigned long end_addr, int force)
560 {
561 	/*
562 	 * Don't bother flushing if this address space is about to be
563 	 * destroyed.
564 	 */
565 	if (atomic_read(&mm->mm_users) == 0)
566 		return;
567 
568 	fix_range_common(mm, start_addr, end_addr, force);
569 }
570 
571 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
572 		     unsigned long end)
573 {
574 	if (vma->vm_mm == NULL)
575 		flush_tlb_kernel_range_common(start, end);
576 	else fix_range(vma->vm_mm, start, end, 0);
577 }
578 EXPORT_SYMBOL(flush_tlb_range);
579 
580 void flush_tlb_mm(struct mm_struct *mm)
581 {
582 	struct vm_area_struct *vma;
583 	VMA_ITERATOR(vmi, mm, 0);
584 
585 	for_each_vma(vmi, vma)
586 		fix_range(mm, vma->vm_start, vma->vm_end, 0);
587 }
588 
589 void force_flush_all(void)
590 {
591 	struct mm_struct *mm = current->mm;
592 	struct vm_area_struct *vma;
593 	VMA_ITERATOR(vmi, mm, 0);
594 
595 	mmap_read_lock(mm);
596 	for_each_vma(vmi, vma)
597 		fix_range(mm, vma->vm_start, vma->vm_end, 1);
598 	mmap_read_unlock(mm);
599 }
600