1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright IBM Corp. 2006
4 */
5
6 #include <linux/memory_hotplug.h>
7 #include <linux/memblock.h>
8 #include <linux/pfn.h>
9 #include <linux/mm.h>
10 #include <linux/init.h>
11 #include <linux/list.h>
12 #include <linux/hugetlb.h>
13 #include <linux/slab.h>
14 #include <linux/sort.h>
15 #include <asm/page-states.h>
16 #include <asm/abs_lowcore.h>
17 #include <asm/cacheflush.h>
18 #include <asm/maccess.h>
19 #include <asm/nospec-branch.h>
20 #include <asm/ctlreg.h>
21 #include <asm/pgalloc.h>
22 #include <asm/setup.h>
23 #include <asm/tlbflush.h>
24 #include <asm/sections.h>
25 #include <asm/set_memory.h>
26 #include <asm/physmem_info.h>
27
28 static DEFINE_MUTEX(vmem_mutex);
29
30 static void __ref *vmem_alloc_pages(unsigned int order)
31 {
32 unsigned long size = PAGE_SIZE << order;
33
34 if (slab_is_available())
35 return (void *)__get_free_pages(GFP_KERNEL, order);
36 return memblock_alloc(size, size);
37 }
38
39 static void vmem_free_pages(unsigned long addr, int order, struct vmem_altmap *altmap)
40 {
41 if (altmap) {
42 vmem_altmap_free(altmap, 1 << order);
43 return;
44 }
45 /* We don't expect boot memory to be removed ever. */
46 if (!slab_is_available() ||
47 WARN_ON_ONCE(PageReserved(virt_to_page((void *)addr))))
48 return;
49 free_pages(addr, order);
50 }
51
52 void *vmem_crst_alloc(unsigned long val)
53 {
54 unsigned long *table;
55
56 table = vmem_alloc_pages(CRST_ALLOC_ORDER);
57 if (!table)
58 return NULL;
59 crst_table_init(table, val);
60 __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
61 return table;
62 }
63
64 pte_t __ref *vmem_pte_alloc(void)
65 {
66 unsigned long size = PTRS_PER_PTE * sizeof(pte_t);
67 pte_t *pte;
68
69 if (slab_is_available())
70 pte = (pte_t *) page_table_alloc(&init_mm);
71 else
72 pte = (pte_t *) memblock_alloc(size, size);
73 if (!pte)
74 return NULL;
75 memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
76 __arch_set_page_dat(pte, 1);
77 return pte;
78 }
79
80 static void vmem_pte_free(unsigned long *table)
81 {
82 /* We don't expect boot memory to be removed ever. */
83 if (!slab_is_available() ||
84 WARN_ON_ONCE(PageReserved(virt_to_page(table))))
85 return;
86 page_table_free(&init_mm, table);
87 }
88
89 #define PAGE_UNUSED 0xFD
90
91 /*
92 * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
93 * from unused_sub_pmd_start to next PMD_SIZE boundary.
94 */
95 static unsigned long unused_sub_pmd_start;
96
97 static void vmemmap_flush_unused_sub_pmd(void)
98 {
99 if (!unused_sub_pmd_start)
100 return;
101 memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
102 ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
103 unused_sub_pmd_start = 0;
104 }
105
106 static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
107 {
108 /*
109 * As we expect to add in the same granularity as we remove, it's
110 * sufficient to mark only some piece used to block the memmap page from
111 * getting removed (just in case the memmap never gets initialized,
112 * e.g., because the memory block never gets onlined).
113 */
114 memset((void *)start, 0, sizeof(struct page));
115 }
116
117 static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
118 {
119 /*
120 * We only optimize if the new used range directly follows the
121 * previously unused range (esp., when populating consecutive sections).
122 */
123 if (unused_sub_pmd_start == start) {
124 unused_sub_pmd_start = end;
125 if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
126 unused_sub_pmd_start = 0;
127 return;
128 }
129 vmemmap_flush_unused_sub_pmd();
130 vmemmap_mark_sub_pmd_used(start, end);
131 }
132
133 static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
134 {
135 unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
136
137 vmemmap_flush_unused_sub_pmd();
138
139 /* Could be our memmap page is filled with PAGE_UNUSED already ... */
140 vmemmap_mark_sub_pmd_used(start, end);
141
142 /* Mark the unused parts of the new memmap page PAGE_UNUSED. */
143 if (!IS_ALIGNED(start, PMD_SIZE))
144 memset((void *)page, PAGE_UNUSED, start - page);
145 /*
146 * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
147 * consecutive sections. Remember for the last added PMD the last
148 * unused range in the populated PMD.
149 */
150 if (!IS_ALIGNED(end, PMD_SIZE))
151 unused_sub_pmd_start = end;
152 }
153
154 /* Returns true if the PMD is completely unused and can be freed. */
155 static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
156 {
157 unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
158
159 vmemmap_flush_unused_sub_pmd();
160 memset((void *)start, PAGE_UNUSED, end - start);
161 return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
162 }
163
164 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
165 static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
166 unsigned long end, bool add, bool direct,
167 struct vmem_altmap *altmap)
168 {
169 unsigned long prot, pages = 0;
170 int ret = -ENOMEM;
171 pte_t *pte;
172
173 prot = pgprot_val(PAGE_KERNEL);
174 if (!MACHINE_HAS_NX)
175 prot &= ~_PAGE_NOEXEC;
176
177 pte = pte_offset_kernel(pmd, addr);
178 for (; addr < end; addr += PAGE_SIZE, pte++) {
179 if (!add) {
180 if (pte_none(*pte))
181 continue;
182 if (!direct)
183 vmem_free_pages((unsigned long)pfn_to_virt(pte_pfn(*pte)), get_order(PAGE_SIZE), altmap);
184 pte_clear(&init_mm, addr, pte);
185 } else if (pte_none(*pte)) {
186 if (!direct) {
187 void *new_page = vmemmap_alloc_block_buf(PAGE_SIZE, NUMA_NO_NODE, altmap);
188
189 if (!new_page)
190 goto out;
191 set_pte(pte, __pte(__pa(new_page) | prot));
192 } else {
193 set_pte(pte, __pte(__pa(addr) | prot));
194 }
195 } else {
196 continue;
197 }
198 pages++;
199 }
200 ret = 0;
201 out:
202 if (direct)
203 update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
204 return ret;
205 }
206
207 static void try_free_pte_table(pmd_t *pmd, unsigned long start)
208 {
209 pte_t *pte;
210 int i;
211
212 /* We can safely assume this is fully in 1:1 mapping & vmemmap area */
213 pte = pte_offset_kernel(pmd, start);
214 for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
215 if (!pte_none(*pte))
216 return;
217 }
218 vmem_pte_free((unsigned long *) pmd_deref(*pmd));
219 pmd_clear(pmd);
220 }
221
222 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
223 static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
224 unsigned long end, bool add, bool direct,
225 struct vmem_altmap *altmap)
226 {
227 unsigned long next, prot, pages = 0;
228 int ret = -ENOMEM;
229 pmd_t *pmd;
230 pte_t *pte;
231
232 prot = pgprot_val(SEGMENT_KERNEL);
233 if (!MACHINE_HAS_NX)
234 prot &= ~_SEGMENT_ENTRY_NOEXEC;
235
236 pmd = pmd_offset(pud, addr);
237 for (; addr < end; addr = next, pmd++) {
238 next = pmd_addr_end(addr, end);
239 if (!add) {
240 if (pmd_none(*pmd))
241 continue;
242 if (pmd_leaf(*pmd)) {
243 if (IS_ALIGNED(addr, PMD_SIZE) &&
244 IS_ALIGNED(next, PMD_SIZE)) {
245 if (!direct)
246 vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
247 pmd_clear(pmd);
248 pages++;
249 } else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
250 vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
251 pmd_clear(pmd);
252 }
253 continue;
254 }
255 } else if (pmd_none(*pmd)) {
256 if (IS_ALIGNED(addr, PMD_SIZE) &&
257 IS_ALIGNED(next, PMD_SIZE) &&
258 MACHINE_HAS_EDAT1 && direct &&
259 !debug_pagealloc_enabled()) {
260 set_pmd(pmd, __pmd(__pa(addr) | prot));
261 pages++;
262 continue;
263 } else if (!direct && MACHINE_HAS_EDAT1) {
264 void *new_page;
265
266 /*
267 * Use 1MB frames for vmemmap if available. We
268 * always use large frames even if they are only
269 * partially used. Otherwise we would have also
270 * page tables since vmemmap_populate gets
271 * called for each section separately.
272 */
273 new_page = vmemmap_alloc_block_buf(PMD_SIZE, NUMA_NO_NODE, altmap);
274 if (new_page) {
275 set_pmd(pmd, __pmd(__pa(new_page) | prot));
276 if (!IS_ALIGNED(addr, PMD_SIZE) ||
277 !IS_ALIGNED(next, PMD_SIZE)) {
278 vmemmap_use_new_sub_pmd(addr, next);
279 }
280 continue;
281 }
282 }
283 pte = vmem_pte_alloc();
284 if (!pte)
285 goto out;
286 pmd_populate(&init_mm, pmd, pte);
287 } else if (pmd_leaf(*pmd)) {
288 if (!direct)
289 vmemmap_use_sub_pmd(addr, next);
290 continue;
291 }
292 ret = modify_pte_table(pmd, addr, next, add, direct, altmap);
293 if (ret)
294 goto out;
295 if (!add)
296 try_free_pte_table(pmd, addr & PMD_MASK);
297 }
298 ret = 0;
299 out:
300 if (direct)
301 update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
302 return ret;
303 }
304
305 static void try_free_pmd_table(pud_t *pud, unsigned long start)
306 {
307 pmd_t *pmd;
308 int i;
309
310 pmd = pmd_offset(pud, start);
311 for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
312 if (!pmd_none(*pmd))
313 return;
314 vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER, NULL);
315 pud_clear(pud);
316 }
317
318 static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
319 bool add, bool direct, struct vmem_altmap *altmap)
320 {
321 unsigned long next, prot, pages = 0;
322 int ret = -ENOMEM;
323 pud_t *pud;
324 pmd_t *pmd;
325
326 prot = pgprot_val(REGION3_KERNEL);
327 if (!MACHINE_HAS_NX)
328 prot &= ~_REGION_ENTRY_NOEXEC;
329 pud = pud_offset(p4d, addr);
330 for (; addr < end; addr = next, pud++) {
331 next = pud_addr_end(addr, end);
332 if (!add) {
333 if (pud_none(*pud))
334 continue;
335 if (pud_leaf(*pud)) {
336 if (IS_ALIGNED(addr, PUD_SIZE) &&
337 IS_ALIGNED(next, PUD_SIZE)) {
338 pud_clear(pud);
339 pages++;
340 }
341 continue;
342 }
343 } else if (pud_none(*pud)) {
344 if (IS_ALIGNED(addr, PUD_SIZE) &&
345 IS_ALIGNED(next, PUD_SIZE) &&
346 MACHINE_HAS_EDAT2 && direct &&
347 !debug_pagealloc_enabled()) {
348 set_pud(pud, __pud(__pa(addr) | prot));
349 pages++;
350 continue;
351 }
352 pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
353 if (!pmd)
354 goto out;
355 pud_populate(&init_mm, pud, pmd);
356 } else if (pud_leaf(*pud)) {
357 continue;
358 }
359 ret = modify_pmd_table(pud, addr, next, add, direct, altmap);
360 if (ret)
361 goto out;
362 if (!add)
363 try_free_pmd_table(pud, addr & PUD_MASK);
364 }
365 ret = 0;
366 out:
367 if (direct)
368 update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
369 return ret;
370 }
371
372 static void try_free_pud_table(p4d_t *p4d, unsigned long start)
373 {
374 pud_t *pud;
375 int i;
376
377 pud = pud_offset(p4d, start);
378 for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
379 if (!pud_none(*pud))
380 return;
381 }
382 vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER, NULL);
383 p4d_clear(p4d);
384 }
385
386 static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
387 bool add, bool direct, struct vmem_altmap *altmap)
388 {
389 unsigned long next;
390 int ret = -ENOMEM;
391 p4d_t *p4d;
392 pud_t *pud;
393
394 p4d = p4d_offset(pgd, addr);
395 for (; addr < end; addr = next, p4d++) {
396 next = p4d_addr_end(addr, end);
397 if (!add) {
398 if (p4d_none(*p4d))
399 continue;
400 } else if (p4d_none(*p4d)) {
401 pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
402 if (!pud)
403 goto out;
404 p4d_populate(&init_mm, p4d, pud);
405 }
406 ret = modify_pud_table(p4d, addr, next, add, direct, altmap);
407 if (ret)
408 goto out;
409 if (!add)
410 try_free_pud_table(p4d, addr & P4D_MASK);
411 }
412 ret = 0;
413 out:
414 return ret;
415 }
416
417 static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
418 {
419 p4d_t *p4d;
420 int i;
421
422 p4d = p4d_offset(pgd, start);
423 for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
424 if (!p4d_none(*p4d))
425 return;
426 }
427 vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER, NULL);
428 pgd_clear(pgd);
429 }
430
431 static int modify_pagetable(unsigned long start, unsigned long end, bool add,
432 bool direct, struct vmem_altmap *altmap)
433 {
434 unsigned long addr, next;
435 int ret = -ENOMEM;
436 pgd_t *pgd;
437 p4d_t *p4d;
438
439 if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end)))
440 return -EINVAL;
441 /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
442 if (WARN_ON_ONCE(end > __abs_lowcore))
443 return -EINVAL;
444 for (addr = start; addr < end; addr = next) {
445 next = pgd_addr_end(addr, end);
446 pgd = pgd_offset_k(addr);
447
448 if (!add) {
449 if (pgd_none(*pgd))
450 continue;
451 } else if (pgd_none(*pgd)) {
452 p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
453 if (!p4d)
454 goto out;
455 pgd_populate(&init_mm, pgd, p4d);
456 }
457 ret = modify_p4d_table(pgd, addr, next, add, direct, altmap);
458 if (ret)
459 goto out;
460 if (!add)
461 try_free_p4d_table(pgd, addr & PGDIR_MASK);
462 }
463 ret = 0;
464 out:
465 if (!add)
466 flush_tlb_kernel_range(start, end);
467 return ret;
468 }
469
470 static int add_pagetable(unsigned long start, unsigned long end, bool direct,
471 struct vmem_altmap *altmap)
472 {
473 return modify_pagetable(start, end, true, direct, altmap);
474 }
475
476 static int remove_pagetable(unsigned long start, unsigned long end, bool direct,
477 struct vmem_altmap *altmap)
478 {
479 return modify_pagetable(start, end, false, direct, altmap);
480 }
481
482 /*
483 * Add a physical memory range to the 1:1 mapping.
484 */
485 static int vmem_add_range(unsigned long start, unsigned long size)
486 {
487 start = (unsigned long)__va(start);
488 return add_pagetable(start, start + size, true, NULL);
489 }
490
491 /*
492 * Remove a physical memory range from the 1:1 mapping.
493 */
494 static void vmem_remove_range(unsigned long start, unsigned long size)
495 {
496 start = (unsigned long)__va(start);
497 remove_pagetable(start, start + size, true, NULL);
498 }
499
500 /*
501 * Add a backed mem_map array to the virtual mem_map array.
502 */
503 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
504 struct vmem_altmap *altmap)
505 {
506 int ret;
507
508 mutex_lock(&vmem_mutex);
509 /* We don't care about the node, just use NUMA_NO_NODE on allocations */
510 ret = add_pagetable(start, end, false, altmap);
511 if (ret)
512 remove_pagetable(start, end, false, altmap);
513 mutex_unlock(&vmem_mutex);
514 return ret;
515 }
516
517 #ifdef CONFIG_MEMORY_HOTPLUG
518
519 void vmemmap_free(unsigned long start, unsigned long end,
520 struct vmem_altmap *altmap)
521 {
522 mutex_lock(&vmem_mutex);
523 remove_pagetable(start, end, false, altmap);
524 mutex_unlock(&vmem_mutex);
525 }
526
527 #endif
528
529 void vmem_remove_mapping(unsigned long start, unsigned long size)
530 {
531 mutex_lock(&vmem_mutex);
532 vmem_remove_range(start, size);
533 mutex_unlock(&vmem_mutex);
534 }
535
536 struct range arch_get_mappable_range(void)
537 {
538 struct range mhp_range;
539
540 mhp_range.start = 0;
541 mhp_range.end = max_mappable - 1;
542 return mhp_range;
543 }
544
545 int vmem_add_mapping(unsigned long start, unsigned long size)
546 {
547 struct range range = arch_get_mappable_range();
548 int ret;
549
550 if (start < range.start ||
551 start + size > range.end + 1 ||
552 start + size < start)
553 return -ERANGE;
554
555 mutex_lock(&vmem_mutex);
556 ret = vmem_add_range(start, size);
557 if (ret)
558 vmem_remove_range(start, size);
559 mutex_unlock(&vmem_mutex);
560 return ret;
561 }
562
563 /*
564 * Allocate new or return existing page-table entry, but do not map it
565 * to any physical address. If missing, allocate segment- and region-
566 * table entries along. Meeting a large segment- or region-table entry
567 * while traversing is an error, since the function is expected to be
568 * called against virtual regions reserved for 4KB mappings only.
569 */
570 pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc)
571 {
572 pte_t *ptep = NULL;
573 pgd_t *pgd;
574 p4d_t *p4d;
575 pud_t *pud;
576 pmd_t *pmd;
577 pte_t *pte;
578
579 pgd = pgd_offset_k(addr);
580 if (pgd_none(*pgd)) {
581 if (!alloc)
582 goto out;
583 p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
584 if (!p4d)
585 goto out;
586 pgd_populate(&init_mm, pgd, p4d);
587 }
588 p4d = p4d_offset(pgd, addr);
589 if (p4d_none(*p4d)) {
590 if (!alloc)
591 goto out;
592 pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
593 if (!pud)
594 goto out;
595 p4d_populate(&init_mm, p4d, pud);
596 }
597 pud = pud_offset(p4d, addr);
598 if (pud_none(*pud)) {
599 if (!alloc)
600 goto out;
601 pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
602 if (!pmd)
603 goto out;
604 pud_populate(&init_mm, pud, pmd);
605 } else if (WARN_ON_ONCE(pud_leaf(*pud))) {
606 goto out;
607 }
608 pmd = pmd_offset(pud, addr);
609 if (pmd_none(*pmd)) {
610 if (!alloc)
611 goto out;
612 pte = vmem_pte_alloc();
613 if (!pte)
614 goto out;
615 pmd_populate(&init_mm, pmd, pte);
616 } else if (WARN_ON_ONCE(pmd_leaf(*pmd))) {
617 goto out;
618 }
619 ptep = pte_offset_kernel(pmd, addr);
620 out:
621 return ptep;
622 }
623
624 int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc)
625 {
626 pte_t *ptep, pte;
627
628 if (!IS_ALIGNED(addr, PAGE_SIZE))
629 return -EINVAL;
630 ptep = vmem_get_alloc_pte(addr, alloc);
631 if (!ptep)
632 return -ENOMEM;
633 __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
634 pte = mk_pte_phys(phys, prot);
635 set_pte(ptep, pte);
636 return 0;
637 }
638
639 int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot)
640 {
641 int rc;
642
643 mutex_lock(&vmem_mutex);
644 rc = __vmem_map_4k_page(addr, phys, prot, true);
645 mutex_unlock(&vmem_mutex);
646 return rc;
647 }
648
649 void vmem_unmap_4k_page(unsigned long addr)
650 {
651 pte_t *ptep;
652
653 mutex_lock(&vmem_mutex);
654 ptep = virt_to_kpte(addr);
655 __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
656 pte_clear(&init_mm, addr, ptep);
657 mutex_unlock(&vmem_mutex);
658 }
659
660 void __init vmem_map_init(void)
661 {
662 __set_memory_rox(_stext, _etext);
663 __set_memory_ro(_etext, __end_rodata);
664 __set_memory_rox(__stext_amode31, __etext_amode31);
665 /*
666 * If the BEAR-enhancement facility is not installed the first
667 * prefix page is used to return to the previous context with
668 * an LPSWE instruction and therefore must be executable.
669 */
670 if (!static_key_enabled(&cpu_has_bear))
671 set_memory_x(0, 1);
672 if (debug_pagealloc_enabled())
673 __set_memory_4k(__va(0), __va(0) + ident_map_size);
674 pr_info("Write protected kernel read-only data: %luk\n",
675 (unsigned long)(__end_rodata - _stext) >> 10);
676 }
677
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.