1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
|
#include "MemoryManager.h"
#include <AK/Assertions.h>
#include <AK/kstdio.h>
#include <AK/kmalloc.h>
#include "i386.h"
#include "StdLib.h"
#include "Process.h"
#include <LibC/errno_numbers.h>
#include "CMOS.h"
//#define MM_DEBUG
//#define PAGE_FAULT_DEBUG
static MemoryManager* s_the;
MemoryManager& MM
{
return *s_the;
}
MemoryManager::MemoryManager()
{
// FIXME: This is not the best way to do memory map detection.
// Rewrite to use BIOS int 15,e820 once we have VM86 support.
word base_memory = (CMOS::read(0x16) << 8) | CMOS::read(0x15);
word ext_memory = (CMOS::read(0x18) << 8) | CMOS::read(0x17);
kprintf("%u kB base memory\n", base_memory);
kprintf("%u kB extended memory\n", ext_memory);
m_ram_size = ext_memory * 1024;
m_kernel_page_directory = PageDirectory::create_at_fixed_address(PhysicalAddress(0x4000));
m_page_table_zero = (dword*)0x6000;
initialize_paging();
}
MemoryManager::~MemoryManager()
{
}
PageDirectory::PageDirectory(PhysicalAddress paddr)
{
m_directory_page = adopt(*new PhysicalPage(paddr, true));
}
PageDirectory::PageDirectory()
{
MM.populate_page_directory(*this);
}
void MemoryManager::populate_page_directory(PageDirectory& page_directory)
{
page_directory.m_directory_page = allocate_supervisor_physical_page();
page_directory.entries()[0] = kernel_page_directory().entries()[0];
}
void MemoryManager::initialize_paging()
{
static_assert(sizeof(MemoryManager::PageDirectoryEntry) == 4);
static_assert(sizeof(MemoryManager::PageTableEntry) == 4);
memset(m_page_table_zero, 0, PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Kernel page directory @ %p\n", kernel_page_directory().cr3());
#endif
#ifdef MM_DEBUG
dbgprintf("MM: Protect against null dereferences\n");
#endif
// Make null dereferences crash.
map_protected(LinearAddress(0), PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Identity map bottom 4MB\n");
#endif
// The bottom 4 MB (except for the null page) are identity mapped & supervisor only.
// Every process shares these mappings.
create_identity_mapping(kernel_page_directory(), LinearAddress(PAGE_SIZE), (4 * MB) - PAGE_SIZE);
// Basic memory map:
// 0 -> 512 kB Kernel code. Root page directory & PDE 0.
// (last page before 1MB) Used by quickmap_page().
// 1 MB -> 2 MB kmalloc_eternal() space.
// 2 MB -> 3 MB kmalloc() space.
// 3 MB -> 4 MB Supervisor physical pages (available for allocation!)
// 4 MB -> (max) MB Userspace physical pages (available for allocation!)
for (size_t i = (2 * MB); i < (4 * MB); i += PAGE_SIZE)
m_free_supervisor_physical_pages.append(adopt(*new PhysicalPage(PhysicalAddress(i), true)));
dbgprintf("MM: 4MB-%uMB available for allocation\n", m_ram_size / 1048576);
for (size_t i = (4 * MB); i < m_ram_size; i += PAGE_SIZE)
m_free_physical_pages.append(adopt(*new PhysicalPage(PhysicalAddress(i), false)));
m_quickmap_addr = LinearAddress((1 * MB) - PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Quickmap will use P%x\n", m_quickmap_addr.get());
dbgprintf("MM: Installing page directory\n");
#endif
asm volatile("movl %%eax, %%cr3"::"a"(kernel_page_directory().cr3()));
asm volatile(
"movl %%cr0, %%eax\n"
"orl $0x80000001, %%eax\n"
"movl %%eax, %%cr0\n"
:::"%eax", "memory");
}
RetainPtr<PhysicalPage> MemoryManager::allocate_page_table(PageDirectory& page_directory, unsigned index)
{
ASSERT(!page_directory.m_physical_pages.contains(index));
auto physical_page = allocate_supervisor_physical_page();
if (!physical_page)
return nullptr;
page_directory.m_physical_pages.set(index, physical_page.copy_ref());
return physical_page;
}
void MemoryManager::remove_identity_mapping(PageDirectory& page_directory, LinearAddress laddr, size_t size)
{
InterruptDisabler disabler;
// FIXME: ASSERT(laddr is 4KB aligned);
for (dword offset = 0; offset < size; offset += PAGE_SIZE) {
auto pte_address = laddr.offset(offset);
auto pte = ensure_pte(page_directory, pte_address);
pte.set_physical_page_base(0);
pte.set_user_allowed(false);
pte.set_present(true);
pte.set_writable(true);
flush_tlb(pte_address);
}
}
auto MemoryManager::ensure_pte(PageDirectory& page_directory, LinearAddress laddr) -> PageTableEntry
{
ASSERT_INTERRUPTS_DISABLED();
dword page_directory_index = (laddr.get() >> 22) & 0x3ff;
dword page_table_index = (laddr.get() >> 12) & 0x3ff;
PageDirectoryEntry pde = PageDirectoryEntry(&page_directory.entries()[page_directory_index]);
if (!pde.is_present()) {
#ifdef MM_DEBUG
dbgprintf("MM: PDE %u not present (requested for L%x), allocating\n", page_directory_index, laddr.get());
#endif
if (page_directory_index == 0) {
ASSERT(&page_directory == m_kernel_page_directory.ptr());
pde.set_page_table_base((dword)m_page_table_zero);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
} else {
ASSERT(&page_directory != m_kernel_page_directory.ptr());
auto page_table = allocate_page_table(page_directory, page_directory_index);
#ifdef MM_DEBUG
dbgprintf("MM: PD K%x (%s) at P%x allocated page table #%u (for L%x) at P%x\n",
&page_directory,
&page_directory == m_kernel_page_directory.ptr() ? "Kernel" : "User",
page_directory.cr3(),
page_directory_index,
laddr.get(),
page_table->paddr().get());
#endif
pde.set_page_table_base(page_table->paddr().get());
pde.set_user_allowed(true);
pde.set_present(true);
pde.set_writable(true);
page_directory.m_physical_pages.set(page_directory_index, move(page_table));
}
}
return PageTableEntry(&pde.page_table_base()[page_table_index]);
}
void MemoryManager::map_protected(LinearAddress laddr, size_t length)
{
InterruptDisabler disabler;
// FIXME: ASSERT(linearAddress is 4KB aligned);
for (dword offset = 0; offset < length; offset += PAGE_SIZE) {
auto pte_address = laddr.offset(offset);
auto pte = ensure_pte(kernel_page_directory(), pte_address);
pte.set_physical_page_base(pte_address.get());
pte.set_user_allowed(false);
pte.set_present(false);
pte.set_writable(false);
flush_tlb(pte_address);
}
}
void MemoryManager::create_identity_mapping(PageDirectory& page_directory, LinearAddress laddr, size_t size)
{
InterruptDisabler disabler;
ASSERT((laddr.get() & ~PAGE_MASK) == 0);
for (dword offset = 0; offset < size; offset += PAGE_SIZE) {
auto pte_address = laddr.offset(offset);
auto pte = ensure_pte(page_directory, pte_address);
pte.set_physical_page_base(pte_address.get());
pte.set_user_allowed(false);
pte.set_present(true);
pte.set_writable(true);
page_directory.flush(pte_address);
}
}
void MemoryManager::initialize()
{
s_the = new MemoryManager;
}
Region* MemoryManager::region_from_laddr(Process& process, LinearAddress laddr)
{
ASSERT_INTERRUPTS_DISABLED();
// FIXME: Use a binary search tree (maybe red/black?) or some other more appropriate data structure!
for (auto& region : process.m_regions) {
if (region->contains(laddr))
return region.ptr();
}
dbgprintf("%s(%u) Couldn't find region for L%x (CR3=%x)\n", process.name().characters(), process.pid(), laddr.get(), process.page_directory().cr3());
return nullptr;
}
const Region* MemoryManager::region_from_laddr(const Process& process, LinearAddress laddr)
{
// FIXME: Use a binary search tree (maybe red/black?) or some other more appropriate data structure!
for (auto& region : process.m_regions) {
if (region->contains(laddr))
return region.ptr();
}
dbgprintf("%s(%u) Couldn't find region for L%x (CR3=%x)\n", process.name().characters(), process.pid(), laddr.get(), process.page_directory().cr3());
return nullptr;
}
bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmo = region.vmo();
auto physical_page = allocate_physical_page(ShouldZeroFill::Yes);
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> ZERO P%x\n", physical_page->paddr().get());
#endif
region.m_cow_map.set(page_index_in_region, false);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
remap_region_page(region, page_index_in_region, true);
return true;
}
bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmo = region.vmo();
if (vmo.physical_pages()[page_index_in_region]->retain_count() == 1) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
#endif
region.m_cow_map.set(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
return true;
}
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> It's a COW page and it's time to COW!\n");
#endif
auto physical_page_to_copy = move(vmo.physical_pages()[page_index_in_region]);
auto physical_page = allocate_physical_page(ShouldZeroFill::No);
byte* dest_ptr = quickmap_page(*physical_page);
const byte* src_ptr = region.laddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> COW P%x <- P%x\n", physical_page->paddr().get(), physical_page_to_copy->paddr().get());
#endif
memcpy(dest_ptr, src_ptr, PAGE_SIZE);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
unquickmap_page();
region.m_cow_map.set(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
return true;
}
bool Region::page_in()
{
ASSERT(m_page_directory);
ASSERT(!vmo().is_anonymous());
ASSERT(vmo().inode());
#ifdef MM_DEBUG
dbgprintf("MM: page_in %u pages\n", page_count());
#endif
for (size_t i = 0; i < page_count(); ++i) {
auto& vmo_page = vmo().physical_pages()[first_page_index() + i];
if (vmo_page.is_null()) {
bool success = MM.page_in_from_inode(*this, i);
if (!success)
return false;
}
MM.remap_region_page(*this, i, true);
}
return true;
}
bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_region)
{
ASSERT(region.page_directory());
auto& vmo = region.vmo();
ASSERT(!vmo.is_anonymous());
ASSERT(vmo.inode());
auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
InterruptFlagSaver saver;
sti();
LOCKER(vmo.m_paging_lock);
cli();
if (!vmo_page.is_null()) {
dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
remap_region_page(region, page_index_in_region, true);
return true;
}
#ifdef MM_DEBUG
dbgprintf("MM: page_in_from_inode ready to read from inode\n");
#endif
sti();
byte page_buffer[PAGE_SIZE];
auto& inode = *vmo.inode();
auto nread = inode.read_bytes(vmo.inode_offset() + ((region.first_page_index() + page_index_in_region) * PAGE_SIZE), PAGE_SIZE, page_buffer, nullptr);
if (nread < 0) {
kprintf("MM: page_in_from_inode had error (%d) while reading!\n", nread);
return false;
}
if (nread < PAGE_SIZE) {
// If we read less than a page, zero out the rest to avoid leaking uninitialized data.
memset(page_buffer + nread, 0, PAGE_SIZE - nread);
}
cli();
vmo_page = allocate_physical_page(ShouldZeroFill::No);
if (vmo_page.is_null()) {
kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
return false;
}
remap_region_page(region, page_index_in_region, true);
byte* dest_ptr = region.laddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
memcpy(dest_ptr, page_buffer, PAGE_SIZE);
return true;
}
PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
{
ASSERT_INTERRUPTS_DISABLED();
#ifdef PAGE_FAULT_DEBUG
dbgprintf("MM: handle_page_fault(%w) at L%x\n", fault.code(), fault.laddr().get());
#endif
ASSERT(fault.laddr() != m_quickmap_addr);
auto* region = region_from_laddr(*current, fault.laddr());
if (!region) {
kprintf("NP(error) fault at invalid address L%x\n", fault.laddr().get());
return PageFaultResponse::ShouldCrash;
}
auto page_index_in_region = region->page_index_from_address(fault.laddr());
if (fault.is_not_present()) {
if (region->vmo().inode()) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(inode) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
page_in_from_inode(*region, page_index_in_region);
return PageFaultResponse::Continue;
} else {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(zero) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
zero_page(*region, page_index_in_region);
return PageFaultResponse::Continue;
}
} else if (fault.is_protection_violation()) {
if (region->m_cow_map.get(page_index_in_region)) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("PV(cow) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
bool success = copy_on_write(*region, page_index_in_region);
ASSERT(success);
return PageFaultResponse::Continue;
}
kprintf("PV(error) fault in Region{%p}[%u]\n", region, page_index_in_region);
} else {
ASSERT_NOT_REACHED();
}
return PageFaultResponse::ShouldCrash;
}
RetainPtr<PhysicalPage> MemoryManager::allocate_physical_page(ShouldZeroFill should_zero_fill)
{
InterruptDisabler disabler;
if (1 > m_free_physical_pages.size())
return { };
#ifdef MM_DEBUG
dbgprintf("MM: allocate_physical_page vending P%x (%u remaining)\n", m_free_physical_pages.last()->paddr().get(), m_free_physical_pages.size());
#endif
auto physical_page = m_free_physical_pages.take_last();
if (should_zero_fill == ShouldZeroFill::Yes) {
auto* ptr = (dword*)quickmap_page(*physical_page);
fast_dword_fill(ptr, 0, PAGE_SIZE / sizeof(dword));
unquickmap_page();
}
return physical_page;
}
RetainPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
{
InterruptDisabler disabler;
if (1 > m_free_supervisor_physical_pages.size())
return { };
#ifdef MM_DEBUG
dbgprintf("MM: allocate_supervisor_physical_page vending P%x (%u remaining)\n", m_free_supervisor_physical_pages.last()->paddr().get(), m_free_supervisor_physical_pages.size());
#endif
auto physical_page = m_free_supervisor_physical_pages.take_last();
fast_dword_fill((dword*)physical_page->paddr().as_ptr(), 0, PAGE_SIZE / sizeof(dword));
return physical_page;
}
void MemoryManager::enter_process_paging_scope(Process& process)
{
InterruptDisabler disabler;
current->m_tss.cr3 = process.page_directory().cr3();
asm volatile("movl %%eax, %%cr3"::"a"(process.page_directory().cr3()):"memory");
}
void MemoryManager::flush_entire_tlb()
{
asm volatile(
"mov %%cr3, %%eax\n"
"mov %%eax, %%cr3\n"
::: "%eax", "memory"
);
}
void MemoryManager::flush_tlb(LinearAddress laddr)
{
asm volatile("invlpg %0": :"m" (*(char*)laddr.get()) : "memory");
}
byte* MemoryManager::quickmap_page(PhysicalPage& physical_page)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(!m_quickmap_in_use);
m_quickmap_in_use = true;
auto page_laddr = m_quickmap_addr;
auto pte = ensure_pte(kernel_page_directory(), page_laddr);
pte.set_physical_page_base(physical_page.paddr().get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb(page_laddr);
ASSERT((dword)pte.physical_page_base() == physical_page.paddr().get());
#ifdef MM_DEBUG
dbgprintf("MM: >> quickmap_page L%x => P%x @ PTE=%p\n", page_laddr, physical_page.paddr().get(), pte.ptr());
#endif
return page_laddr.as_ptr();
}
void MemoryManager::unquickmap_page()
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(m_quickmap_in_use);
auto page_laddr = m_quickmap_addr;
auto pte = ensure_pte(kernel_page_directory(), page_laddr);
#ifdef MM_DEBUG
auto old_physical_address = pte.physical_page_base();
#endif
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(false);
flush_tlb(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> unquickmap_page L%x =/> P%x\n", page_laddr, old_physical_address);
#endif
m_quickmap_in_use = false;
}
void MemoryManager::remap_region_page(Region& region, unsigned page_index_in_region, bool user_allowed)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
auto page_laddr = region.laddr().offset(page_index_in_region * PAGE_SIZE);
auto pte = ensure_pte(*region.page_directory(), page_laddr);
auto& physical_page = region.vmo().physical_pages()[page_index_in_region];
ASSERT(physical_page);
pte.set_physical_page_base(physical_page->paddr().get());
pte.set_present(true); // FIXME: Maybe we should use the is_readable flag here?
if (region.m_cow_map.get(page_index_in_region))
pte.set_writable(false);
else
pte.set_writable(region.is_writable());
pte.set_cache_disabled(!region.vmo().m_allow_cpu_caching);
pte.set_write_through(!region.vmo().m_allow_cpu_caching);
pte.set_user_allowed(user_allowed);
region.page_directory()->flush(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> remap_region_page (PD=%x, PTE=P%x) '%s' L%x => P%x (@%p)\n", region.page_directory()->cr3(), pte.ptr(), region.name().characters(), page_laddr.get(), physical_page->paddr().get(), physical_page.ptr());
#endif
}
void MemoryManager::remap_region(PageDirectory& page_directory, Region& region)
{
InterruptDisabler disabler;
ASSERT(region.page_directory() == &page_directory);
map_region_at_address(page_directory, region, region.laddr(), true);
}
void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region& region, LinearAddress laddr, bool user_allowed)
{
InterruptDisabler disabler;
region.set_page_directory(page_directory);
auto& vmo = region.vmo();
#ifdef MM_DEBUG
dbgprintf("MM: map_region_at_address will map VMO pages %u - %u (VMO page count: %u)\n", region.first_page_index(), region.last_page_index(), vmo.page_count());
#endif
for (size_t i = 0; i < region.page_count(); ++i) {
auto page_laddr = laddr.offset(i * PAGE_SIZE);
auto pte = ensure_pte(page_directory, page_laddr);
auto& physical_page = vmo.physical_pages()[region.first_page_index() + i];
if (physical_page) {
pte.set_physical_page_base(physical_page->paddr().get());
pte.set_present(true); // FIXME: Maybe we should use the is_readable flag here?
// FIXME: It seems wrong that the *region* cow map is essentially using *VMO* relative indices.
if (region.m_cow_map.get(region.first_page_index() + i))
pte.set_writable(false);
else
pte.set_writable(region.is_writable());
pte.set_cache_disabled(!region.vmo().m_allow_cpu_caching);
pte.set_write_through(!region.vmo().m_allow_cpu_caching);
} else {
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(region.is_writable());
}
pte.set_user_allowed(user_allowed);
page_directory.flush(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> map_region_at_address (PD=%x) '%s' L%x => P%x (@%p)\n", &page_directory, region.name().characters(), page_laddr, physical_page ? physical_page->paddr().get() : 0, physical_page.ptr());
#endif
}
}
bool MemoryManager::unmap_region(Region& region)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
for (size_t i = 0; i < region.page_count(); ++i) {
auto laddr = region.laddr().offset(i * PAGE_SIZE);
auto pte = ensure_pte(*region.page_directory(), laddr);
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(false);
pte.set_user_allowed(false);
region.page_directory()->flush(laddr);
#ifdef MM_DEBUG
auto& physical_page = region.vmo().physical_pages()[region.first_page_index() + i];
dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, physical_page ? physical_page->paddr().get() : 0);
#endif
}
region.release_page_directory();
return true;
}
bool MemoryManager::map_region(Process& process, Region& region)
{
map_region_at_address(process.page_directory(), region, region.laddr(), true);
return true;
}
bool MemoryManager::validate_user_read(const Process& process, LinearAddress laddr) const
{
auto* region = region_from_laddr(process, laddr);
return region && region->is_readable();
}
bool MemoryManager::validate_user_write(const Process& process, LinearAddress laddr) const
{
auto* region = region_from_laddr(process, laddr);
return region && region->is_writable();
}
RetainPtr<Region> Region::clone()
{
if (m_shared || (m_readable && !m_writable)) {
dbgprintf("%s<%u> Region::clone(): sharing %s (L%x)\n",
current->name().characters(),
current->pid(),
m_name.characters(),
laddr().get());
// Create a new region backed by the same VMObject.
return adopt(*new Region(laddr(), size(), m_vmo.copy_ref(), m_offset_in_vmo, String(m_name), m_readable, m_writable));
}
dbgprintf("%s<%u> Region::clone(): cowing %s (L%x)\n",
current->name().characters(),
current->pid(),
m_name.characters(),
laddr().get());
// Set up a COW region. The parent (this) region becomes COW as well!
for (size_t i = 0; i < page_count(); ++i)
m_cow_map.set(i, true);
MM.remap_region(current->page_directory(), *this);
return adopt(*new Region(laddr(), size(), m_vmo->clone(), m_offset_in_vmo, String(m_name), m_readable, m_writable, true));
}
Region::Region(LinearAddress a, size_t s, String&& n, bool r, bool w, bool cow)
: m_laddr(a)
, m_size(s)
, m_vmo(VMObject::create_anonymous(s))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count(), cow))
{
m_vmo->set_name(m_name);
MM.register_region(*this);
}
Region::Region(LinearAddress a, size_t s, RetainPtr<Inode>&& inode, String&& n, bool r, bool w)
: m_laddr(a)
, m_size(s)
, m_vmo(VMObject::create_file_backed(move(inode)))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count()))
{
MM.register_region(*this);
}
Region::Region(LinearAddress a, size_t s, RetainPtr<VMObject>&& vmo, size_t offset_in_vmo, String&& n, bool r, bool w, bool cow)
: m_laddr(a)
, m_size(s)
, m_offset_in_vmo(offset_in_vmo)
, m_vmo(move(vmo))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count(), cow))
{
MM.register_region(*this);
}
Region::~Region()
{
if (m_page_directory) {
MM.unmap_region(*this);
ASSERT(!m_page_directory);
}
MM.unregister_region(*this);
}
PhysicalPage::PhysicalPage(PhysicalAddress paddr, bool supervisor)
: m_supervisor(supervisor)
, m_paddr(paddr)
{
}
void PhysicalPage::return_to_freelist()
{
ASSERT((paddr().get() & ~PAGE_MASK) == 0);
InterruptDisabler disabler;
m_retain_count = 1;
if (m_supervisor)
MM.m_free_supervisor_physical_pages.append(adopt(*this));
else
MM.m_free_physical_pages.append(adopt(*this));
#ifdef MM_DEBUG
dbgprintf("MM: P%x released to freelist\n", m_paddr.get());
#endif
}
RetainPtr<VMObject> VMObject::create_file_backed(RetainPtr<Inode>&& inode)
{
InterruptDisabler disabler;
if (inode->vmo())
return static_cast<VMObject*>(inode->vmo());
auto vmo = adopt(*new VMObject(move(inode)));
vmo->inode()->set_vmo(*vmo);
return vmo;
}
RetainPtr<VMObject> VMObject::create_anonymous(size_t size)
{
size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
return adopt(*new VMObject(size));
}
RetainPtr<VMObject> VMObject::create_for_physical_range(PhysicalAddress paddr, size_t size)
{
size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
auto vmo = adopt(*new VMObject(paddr, size));
vmo->m_allow_cpu_caching = false;
return vmo;
}
RetainPtr<VMObject> VMObject::clone()
{
return adopt(*new VMObject(*this));
}
VMObject::VMObject(VMObject& other)
: m_name(other.m_name)
, m_anonymous(other.m_anonymous)
, m_inode_offset(other.m_inode_offset)
, m_size(other.m_size)
, m_inode(other.m_inode)
, m_physical_pages(other.m_physical_pages)
{
MM.register_vmo(*this);
}
VMObject::VMObject(size_t size)
: m_anonymous(true)
, m_size(size)
{
MM.register_vmo(*this);
m_physical_pages.resize(page_count());
}
VMObject::VMObject(PhysicalAddress paddr, size_t size)
: m_anonymous(true)
, m_size(size)
{
MM.register_vmo(*this);
for (size_t i = 0; i < size; i += PAGE_SIZE) {
m_physical_pages.append(adopt(*new PhysicalPage(paddr.offset(i), false)));
}
ASSERT(m_physical_pages.size() == page_count());
}
VMObject::VMObject(RetainPtr<Inode>&& inode)
: m_inode(move(inode))
{
ASSERT(m_inode);
m_size = ceil_div(m_inode->size(), PAGE_SIZE) * PAGE_SIZE;
m_physical_pages.resize(page_count());
MM.register_vmo(*this);
}
VMObject::~VMObject()
{
if (m_inode)
ASSERT(m_inode->vmo() == this);
MM.unregister_vmo(*this);
}
template<typename Callback>
void VMObject::for_each_region(Callback callback)
{
// FIXME: Figure out a better data structure so we don't have to walk every single region every time an inode changes.
// Perhaps VMObject could have a Vector<Region*> with all of his mappers?
for (auto* region : MM.m_regions) {
if (®ion->vmo() == this)
callback(*region);
}
}
void VMObject::inode_size_changed(Badge<Inode>, size_t old_size, size_t new_size)
{
InterruptDisabler disabler;
size_t old_page_count = page_count();
m_size = new_size;
if (page_count() > old_page_count) {
// Add null pages and let the fault handler page these in when that day comes.
for (size_t i = old_page_count; i < page_count(); ++i)
m_physical_pages.append(nullptr);
} else {
// Prune the no-longer valid pages. I'm not sure this is actually correct behavior.
for (size_t i = page_count(); i < old_page_count; ++i)
m_physical_pages.take_last();
}
// FIXME: Consolidate with inode_contents_changed() so we only do a single walk.
for_each_region([] (Region& region) {
ASSERT(region.page_directory());
MM.remap_region(*region.page_directory(), region);
});
}
void VMObject::inode_contents_changed(Badge<Inode>, off_t offset, size_t size, const byte* data)
{
InterruptDisabler disabler;
ASSERT(offset >= 0);
// FIXME: Only invalidate the parts that actually changed.
for (auto& physical_page : m_physical_pages)
physical_page = nullptr;
#if 0
size_t current_offset = offset;
size_t remaining_bytes = size;
const byte* data_ptr = data;
auto to_page_index = [] (size_t offset) -> size_t {
return offset / PAGE_SIZE;
};
if (current_offset & PAGE_MASK) {
size_t page_index = to_page_index(current_offset);
size_t bytes_to_copy = min(size, PAGE_SIZE - (current_offset & PAGE_MASK));
if (m_physical_pages[page_index]) {
auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
memcpy(ptr, data_ptr, bytes_to_copy);
MM.unquickmap_page();
}
current_offset += bytes_to_copy;
data += bytes_to_copy;
remaining_bytes -= bytes_to_copy;
}
for (size_t page_index = to_page_index(current_offset); page_index < m_physical_pages.size(); ++page_index) {
size_t bytes_to_copy = PAGE_SIZE - (current_offset & PAGE_MASK);
if (m_physical_pages[page_index]) {
auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
memcpy(ptr, data_ptr, bytes_to_copy);
MM.unquickmap_page();
}
current_offset += bytes_to_copy;
data += bytes_to_copy;
}
#endif
// FIXME: Consolidate with inode_size_changed() so we only do a single walk.
for_each_region([] (Region& region) {
ASSERT(region.page_directory());
MM.remap_region(*region.page_directory(), region);
});
}
int Region::commit()
{
InterruptDisabler disabler;
#ifdef MM_DEBUG
dbgprintf("MM: commit %u pages in Region %p (VMO=%p) at L%x\n", vmo().page_count(), this, &vmo(), laddr().get());
#endif
for (size_t i = first_page_index(); i <= last_page_index(); ++i) {
if (!vmo().physical_pages()[i].is_null())
continue;
auto physical_page = MM.allocate_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (!physical_page) {
kprintf("MM: commit was unable to allocate a physical page\n");
return -ENOMEM;
}
vmo().physical_pages()[i] = move(physical_page);
MM.remap_region_page(*this, i, true);
}
return 0;
}
void MemoryManager::register_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmos.set(&vmo);
}
void MemoryManager::unregister_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmos.remove(&vmo);
}
void MemoryManager::register_region(Region& region)
{
InterruptDisabler disabler;
m_regions.set(®ion);
}
void MemoryManager::unregister_region(Region& region)
{
InterruptDisabler disabler;
m_regions.remove(®ion);
}
size_t Region::amount_resident() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
if (m_vmo->physical_pages()[first_page_index() + i])
bytes += PAGE_SIZE;
}
return bytes;
}
size_t Region::amount_shared() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
auto& physical_page = m_vmo->physical_pages()[first_page_index() + i];
if (physical_page && physical_page->retain_count() > 1)
bytes += PAGE_SIZE;
}
return bytes;
}
PageDirectory::~PageDirectory()
{
#ifdef MM_DEBUG
dbgprintf("MM: ~PageDirectory K%x\n", this);
#endif
}
void PageDirectory::flush(LinearAddress laddr)
{
if (¤t->page_directory() == this)
MM.flush_tlb(laddr);
}
|