arch/um/kernel/tlb.c

   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 <as-layout.h>
  12 #include <mem_user.h>
  13 #include <os.h>
  14 #include <skas.h>
  15 #include <kern_util.h>
  16
  17 struct host_vm_change {
  18         struct host_vm_op {
  19                 enum { NONE, MMAP, MUNMAP, MPROTECT } type;
  20                 union {
  21                         struct {
  22                                 unsigned long addr;
  23                                 unsigned long len;
  24                                 unsigned int prot;
  25                                 int fd;
  26                                 __u64 offset;
  27                         } mmap;
  28                         struct {
  29                                 unsigned long addr;
  30                                 unsigned long len;
  31                         } munmap;
  32                         struct {
  33                                 unsigned long addr;
  34                                 unsigned long len;
  35                                 unsigned int prot;
  36                         } mprotect;
  37                 } u;
  38         } ops[1];
  39         int userspace;
  40         int index;
  41         struct mm_struct *mm;
  42         void *data;
  43         int force;
  44 };
  45
  46 #define INIT_HVC(mm, force, userspace) \
  47         ((struct host_vm_change) \
  48          { .ops         = { { .type = NONE } }, \
  49            .mm          = mm, \
  50            .data        = NULL, \
  51            .userspace   = userspace, \
  52            .index       = 0, \
  53            .force       = force })
  54
  55 static void report_enomem(void)
  56 {
  57         printk(KERN_ERR "UML ran out of memory on the host side! "
  58                         "This can happen due to a memory limitation or "
  59                         "vm.max_map_count has been reached.\n");
  60 }
  61
  62 static int do_ops(struct host_vm_change *hvc, int end,
  63                   int finished)
  64 {
  65         struct host_vm_op *op;
  66         int i, ret = 0;
  67
  68         for (i = 0; i < end && !ret; i++) {
  69                 op = &hvc->ops[i];
  70                 switch (op->type) {
  71                 case MMAP:
  72                         if (hvc->userspace)
  73                                 ret = map(&hvc->mm->context.id, op->u.mmap.addr,
  74                                           op->u.mmap.len, op->u.mmap.prot,
  75                                           op->u.mmap.fd,
  76                                           op->u.mmap.offset, finished,
  77                                           &hvc->data);
  78                         else
  79                                 map_memory(op->u.mmap.addr, op->u.mmap.offset,
  80                                            op->u.mmap.len, 1, 1, 1);
  81                         break;
  82                 case MUNMAP:
  83                         if (hvc->userspace)
  84                                 ret = unmap(&hvc->mm->context.id,
  85                                             op->u.munmap.addr,
  86                                             op->u.munmap.len, finished,
  87                                             &hvc->data);
  88                         else
  89                                 ret = os_unmap_memory(
  90                                         (void *) op->u.munmap.addr,
  91                                                       op->u.munmap.len);
  92
  93                         break;
  94                 case MPROTECT:
  95                         if (hvc->userspace)
  96                                 ret = protect(&hvc->mm->context.id,
  97                                               op->u.mprotect.addr,
  98                                               op->u.mprotect.len,
  99                                               op->u.mprotect.prot,
 100                                               finished, &hvc->data);
 101                         else
 102                                 ret = os_protect_memory(
 103                                         (void *) op->u.mprotect.addr,
 104                                                         op->u.mprotect.len,
 105                                                         1, 1, 1);
 106                         break;
 107                 default:
 108                         printk(KERN_ERR "Unknown op type %d in do_ops\n",
 109                                op->type);
 110                         BUG();
 111                         break;
 112                 }
 113         }
 114
 115         if (ret == -ENOMEM)
 116                 report_enomem();
 117
 118         return ret;
 119 }
 120
 121 static int add_mmap(unsigned long virt, unsigned long phys, unsigned long len,
 122                     unsigned int prot, struct host_vm_change *hvc)
 123 {
 124         __u64 offset;
 125         struct host_vm_op *last;
 126         int fd = -1, ret = 0;
 127
 128         if (hvc->userspace)
 129                 fd = phys_mapping(phys, &offset);
 130         else
 131                 offset = phys;
 132         if (hvc->index != 0) {
 133                 last = &hvc->ops[hvc->index - 1];
 134                 if ((last->type == MMAP) &&
 135                    (last->u.mmap.addr + last->u.mmap.len == virt) &&
 136                    (last->u.mmap.prot == prot) && (last->u.mmap.fd == fd) &&
 137                    (last->u.mmap.offset + last->u.mmap.len == offset)) {
 138                         last->u.mmap.len += len;
 139                         return 0;
 140                 }
 141         }
 142
 143         if (hvc->index == ARRAY_SIZE(hvc->ops)) {
 144                 ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
 145                 hvc->index = 0;
 146         }
 147
 148         hvc->ops[hvc->index++] = ((struct host_vm_op)
 149                                   { .type       = MMAP,
 150                                     .u = { .mmap = { .addr      = virt,
 151                                                      .len       = len,
 152                                                      .prot      = prot,
 153                                                      .fd        = fd,
 154                                                      .offset    = offset }
 155                            } });
 156         return ret;
 157 }
 158
 159 static int add_munmap(unsigned long addr, unsigned long len,
 160                       struct host_vm_change *hvc)
 161 {
 162         struct host_vm_op *last;
 163         int ret = 0;
 164
 165         if (hvc->index != 0) {
 166                 last = &hvc->ops[hvc->index - 1];
 167                 if ((last->type == MUNMAP) &&
 168                    (last->u.munmap.addr + last->u.mmap.len == addr)) {
 169                         last->u.munmap.len += len;
 170                         return 0;
 171                 }
 172         }
 173
 174         if (hvc->index == ARRAY_SIZE(hvc->ops)) {
 175                 ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
 176                 hvc->index = 0;
 177         }
 178
 179         hvc->ops[hvc->index++] = ((struct host_vm_op)
 180                                   { .type       = MUNMAP,
 181                                     .u = { .munmap = { .addr    = addr,
 182                                                        .len     = len } } });
 183         return ret;
 184 }
 185
 186 static int add_mprotect(unsigned long addr, unsigned long len,
 187                         unsigned int prot, struct host_vm_change *hvc)
 188 {
 189         struct host_vm_op *last;
 190         int ret = 0;
 191
 192         if (hvc->index != 0) {
 193                 last = &hvc->ops[hvc->index - 1];
 194                 if ((last->type == MPROTECT) &&
 195                    (last->u.mprotect.addr + last->u.mprotect.len == addr) &&
 196                    (last->u.mprotect.prot == prot)) {
 197                         last->u.mprotect.len += len;
 198                         return 0;
 199                 }
 200         }
 201
 202         if (hvc->index == ARRAY_SIZE(hvc->ops)) {
 203                 ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
 204                 hvc->index = 0;
 205         }
 206
 207         hvc->ops[hvc->index++] = ((struct host_vm_op)
 208                                   { .type       = MPROTECT,
 209                                     .u = { .mprotect = { .addr  = addr,
 210                                                          .len   = len,
 211                                                          .prot  = prot } } });
 212         return ret;
 213 }
 214
 215 #define ADD_ROUND(n, inc) (((n) + (inc)) & ~((inc) - 1))
 216
 217 static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
 218                                    unsigned long end,
 219                                    struct host_vm_change *hvc)
 220 {
 221         pte_t *pte;
 222         int r, w, x, prot, ret = 0;
 223
 224         pte = pte_offset_kernel(pmd, addr);
 225         do {
 226                 r = pte_read(*pte);
 227                 w = pte_write(*pte);
 228                 x = pte_exec(*pte);
 229                 if (!pte_young(*pte)) {
 230                         r = 0;
 231                         w = 0;
 232                 } else if (!pte_dirty(*pte))
 233                         w = 0;
 234
 235                 prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
 236                         (x ? UM_PROT_EXEC : 0));
 237                 if (hvc->force || pte_newpage(*pte)) {
 238                         if (pte_present(*pte)) {
 239                                 if (pte_newpage(*pte))
 240                                         ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
 241                                                        PAGE_SIZE, prot, hvc);
 242                         } else
 243                                 ret = add_munmap(addr, PAGE_SIZE, hvc);
 244                 } else if (pte_newprot(*pte))
 245                         ret = add_mprotect(addr, PAGE_SIZE, prot, hvc);
 246                 *pte = pte_mkuptodate(*pte);
 247         } while (pte++, addr += PAGE_SIZE, ((addr < end) && !ret));
 248         return ret;
 249 }
 250
 251 static inline int update_pmd_range(pud_t *pud, unsigned long addr,
 252                                    unsigned long end,
 253                                    struct host_vm_change *hvc)
 254 {
 255         pmd_t *pmd;
 256         unsigned long next;
 257         int ret = 0;
 258
 259         pmd = pmd_offset(pud, addr);
 260         do {
 261                 next = pmd_addr_end(addr, end);
 262                 if (!pmd_present(*pmd)) {
 263                         if (hvc->force || pmd_newpage(*pmd)) {
 264                                 ret = add_munmap(addr, next - addr, hvc);
 265                                 pmd_mkuptodate(*pmd);
 266                         }
 267                 }
 268                 else ret = update_pte_range(pmd, addr, next, hvc);
 269         } while (pmd++, addr = next, ((addr < end) && !ret));
 270         return ret;
 271 }
 272
 273 static inline int update_pud_range(p4d_t *p4d, unsigned long addr,
 274                                    unsigned long end,
 275                                    struct host_vm_change *hvc)
 276 {
 277         pud_t *pud;
 278         unsigned long next;
 279         int ret = 0;
 280
 281         pud = pud_offset(p4d, addr);
 282         do {
 283                 next = pud_addr_end(addr, end);
 284                 if (!pud_present(*pud)) {
 285                         if (hvc->force || pud_newpage(*pud)) {
 286                                 ret = add_munmap(addr, next - addr, hvc);
 287                                 pud_mkuptodate(*pud);
 288                         }
 289                 }
 290                 else ret = update_pmd_range(pud, addr, next, hvc);
 291         } while (pud++, addr = next, ((addr < end) && !ret));
 292         return ret;
 293 }
 294
 295 static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
 296                                    unsigned long end,
 297                                    struct host_vm_change *hvc)
 298 {
 299         p4d_t *p4d;
 300         unsigned long next;
 301         int ret = 0;
 302
 303         p4d = p4d_offset(pgd, addr);
 304         do {
 305                 next = p4d_addr_end(addr, end);
 306                 if (!p4d_present(*p4d)) {
 307                         if (hvc->force || p4d_newpage(*p4d)) {
 308                                 ret = add_munmap(addr, next - addr, hvc);
 309                                 p4d_mkuptodate(*p4d);
 310                         }
 311                 } else
 312                         ret = update_pud_range(p4d, addr, next, hvc);
 313         } while (p4d++, addr = next, ((addr < end) && !ret));
 314         return ret;
 315 }
 316
 317 void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 318                       unsigned long end_addr, int force)
 319 {
 320         pgd_t *pgd;
 321         struct host_vm_change hvc;
 322         unsigned long addr = start_addr, next;
 323         int ret = 0, userspace = 1;
 324
 325         hvc = INIT_HVC(mm, force, userspace);
 326         pgd = pgd_offset(mm, addr);
 327         do {
 328                 next = pgd_addr_end(addr, end_addr);
 329                 if (!pgd_present(*pgd)) {
 330                         if (force || pgd_newpage(*pgd)) {
 331                                 ret = add_munmap(addr, next - addr, &hvc);
 332                                 pgd_mkuptodate(*pgd);
 333                         }
 334                 } else
 335                         ret = update_p4d_range(pgd, addr, next, &hvc);
 336         } while (pgd++, addr = next, ((addr < end_addr) && !ret));
 337
 338         if (!ret)
 339                 ret = do_ops(&hvc, hvc.index, 1);
 340
 341         /* This is not an else because ret is modified above */
 342         if (ret) {
 343                 struct mm_id *mm_idp = &current->mm->context.id;
 344
 345                 printk(KERN_ERR "fix_range_common: failed, killing current "
 346                        "process: %d\n", task_tgid_vnr(current));
 347                 mm_idp->kill = 1;
 348         }
 349 }
 350
 351 static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
 352 {
 353         struct mm_struct *mm;
 354         pgd_t *pgd;
 355         p4d_t *p4d;
 356         pud_t *pud;
 357         pmd_t *pmd;
 358         pte_t *pte;
 359         unsigned long addr, last;
 360         int updated = 0, err = 0, force = 0, userspace = 0;
 361         struct host_vm_change hvc;
 362
 363         mm = &init_mm;
 364         hvc = INIT_HVC(mm, force, userspace);
 365         for (addr = start; addr < end;) {
 366                 pgd = pgd_offset(mm, addr);
 367                 if (!pgd_present(*pgd)) {
 368                         last = ADD_ROUND(addr, PGDIR_SIZE);
 369                         if (last > end)
 370                                 last = end;
 371                         if (pgd_newpage(*pgd)) {
 372                                 updated = 1;
 373                                 err = add_munmap(addr, last - addr, &hvc);
 374                                 if (err < 0)
 375                                         panic("munmap failed, errno = %d\n",
 376                                               -err);
 377                         }
 378                         addr = last;
 379                         continue;
 380                 }
 381
 382                 p4d = p4d_offset(pgd, addr);
 383                 if (!p4d_present(*p4d)) {
 384                         last = ADD_ROUND(addr, P4D_SIZE);
 385                         if (last > end)
 386                                 last = end;
 387                         if (p4d_newpage(*p4d)) {
 388                                 updated = 1;
 389                                 err = add_munmap(addr, last - addr, &hvc);
 390                                 if (err < 0)
 391                                         panic("munmap failed, errno = %d\n",
 392                                               -err);
 393                         }
 394                         addr = last;
 395                         continue;
 396                 }
 397
 398                 pud = pud_offset(p4d, addr);
 399                 if (!pud_present(*pud)) {
 400                         last = ADD_ROUND(addr, PUD_SIZE);
 401                         if (last > end)
 402                                 last = end;
 403                         if (pud_newpage(*pud)) {
 404                                 updated = 1;
 405                                 err = add_munmap(addr, last - addr, &hvc);
 406                                 if (err < 0)
 407                                         panic("munmap failed, errno = %d\n",
 408                                               -err);
 409                         }
 410                         addr = last;
 411                         continue;
 412                 }
 413
 414                 pmd = pmd_offset(pud, addr);
 415                 if (!pmd_present(*pmd)) {
 416                         last = ADD_ROUND(addr, PMD_SIZE);
 417                         if (last > end)
 418                                 last = end;
 419                         if (pmd_newpage(*pmd)) {
 420                                 updated = 1;
 421                                 err = add_munmap(addr, last - addr, &hvc);
 422                                 if (err < 0)
 423                                         panic("munmap failed, errno = %d\n",
 424                                               -err);
 425                         }
 426                         addr = last;
 427                         continue;
 428                 }
 429
 430                 pte = pte_offset_kernel(pmd, addr);
 431                 if (!pte_present(*pte) || pte_newpage(*pte)) {
 432                         updated = 1;
 433                         err = add_munmap(addr, PAGE_SIZE, &hvc);
 434                         if (err < 0)
 435                                 panic("munmap failed, errno = %d\n",
 436                                       -err);
 437                         if (pte_present(*pte))
 438                                 err = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
 439                                                PAGE_SIZE, 0, &hvc);
 440                 }
 441                 else if (pte_newprot(*pte)) {
 442                         updated = 1;
 443                         err = add_mprotect(addr, PAGE_SIZE, 0, &hvc);
 444                 }
 445                 addr += PAGE_SIZE;
 446         }
 447         if (!err)
 448                 err = do_ops(&hvc, hvc.index, 1);
 449
 450         if (err < 0)
 451                 panic("flush_tlb_kernel failed, errno = %d\n", err);
 452         return updated;
 453 }
 454
 455 void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 456 {
 457         pgd_t *pgd;
 458         p4d_t *p4d;
 459         pud_t *pud;
 460         pmd_t *pmd;
 461         pte_t *pte;
 462         struct mm_struct *mm = vma->vm_mm;
 463         void *flush = NULL;
 464         int r, w, x, prot, err = 0;
 465         struct mm_id *mm_id;
 466
 467         address &= PAGE_MASK;
 468
 469         pgd = pgd_offset(mm, address);
 470         if (!pgd_present(*pgd))
 471                 goto kill;
 472
 473         p4d = p4d_offset(pgd, address);
 474         if (!p4d_present(*p4d))
 475                 goto kill;
 476
 477         pud = pud_offset(p4d, address);
 478         if (!pud_present(*pud))
 479                 goto kill;
 480
 481         pmd = pmd_offset(pud, address);
 482         if (!pmd_present(*pmd))
 483                 goto kill;
 484
 485         pte = pte_offset_kernel(pmd, address);
 486
 487         r = pte_read(*pte);
 488         w = pte_write(*pte);
 489         x = pte_exec(*pte);
 490         if (!pte_young(*pte)) {
 491                 r = 0;
 492                 w = 0;
 493         } else if (!pte_dirty(*pte)) {
 494                 w = 0;
 495         }
 496
 497         mm_id = &mm->context.id;
 498         prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
 499                 (x ? UM_PROT_EXEC : 0));
 500         if (pte_newpage(*pte)) {
 501                 if (pte_present(*pte)) {
 502                         unsigned long long offset;
 503                         int fd;
 504
 505                         fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
 506                         err = map(mm_id, address, PAGE_SIZE, prot, fd, offset,
 507                                   1, &flush);
 508                 }
 509                 else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
 510         }
 511         else if (pte_newprot(*pte))
 512                 err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
 513
 514         if (err) {
 515                 if (err == -ENOMEM)
 516                         report_enomem();
 517
 518                 goto kill;
 519         }
 520
 521         *pte = pte_mkuptodate(*pte);
 522
 523         return;
 524
 525 kill:
 526         printk(KERN_ERR "Failed to flush page for address 0x%lx\n", address);
 527         force_sig(SIGKILL);
 528 }
 529
 530 void flush_tlb_all(void)
 531 {
 532         /*
 533          * Don't bother flushing if this address space is about to be
 534          * destroyed.
 535          */
 536         if (atomic_read(&current->mm->mm_users) == 0)
 537                 return;
 538
 539         flush_tlb_mm(current->mm);
 540 }
 541
 542 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 543 {
 544         flush_tlb_kernel_range_common(start, end);
 545 }
 546
 547 void flush_tlb_kernel_vm(void)
 548 {
 549         flush_tlb_kernel_range_common(start_vm, end_vm);
 550 }
 551
 552 void __flush_tlb_one(unsigned long addr)
 553 {
 554         flush_tlb_kernel_range_common(addr, addr + PAGE_SIZE);
 555 }
 556
 557 static void fix_range(struct mm_struct *mm, unsigned long start_addr,
 558                       unsigned long end_addr, int force)
 559 {
 560         /*
 561          * Don't bother flushing if this address space is about to be
 562          * destroyed.
 563          */
 564         if (atomic_read(&mm->mm_users) == 0)
 565                 return;
 566
 567         fix_range_common(mm, start_addr, end_addr, force);
 568 }
 569
 570 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 571                      unsigned long end)
 572 {
 573         if (vma->vm_mm == NULL)
 574                 flush_tlb_kernel_range_common(start, end);
 575         else fix_range(vma->vm_mm, start, end, 0);
 576 }
 577 EXPORT_SYMBOL(flush_tlb_range);
 578
 579 void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 580                         unsigned long end)
 581 {
 582         fix_range(mm, start, end, 0);
 583 }
 584
 585 void flush_tlb_mm(struct mm_struct *mm)
 586 {
 587         struct vm_area_struct *vma = mm->mmap;
 588
 589         while (vma != NULL) {
 590                 fix_range(mm, vma->vm_start, vma->vm_end, 0);
 591                 vma = vma->vm_next;
 592         }
 593 }
 594
 595 void force_flush_all(void)
 596 {
 597         struct mm_struct *mm = current->mm;
 598         struct vm_area_struct *vma = mm->mmap;
 599
 600         while (vma != NULL) {
 601                 fix_range(mm, vma->vm_start, vma->vm_end, 1);
 602                 vma = vma->vm_next;
 603         }
 604 }