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 ((addr >= STUB_START) && (addr < STUB_END))
 166                 return -EINVAL;
 167
 168         if (hvc->index != 0) {
 169                 last = &hvc->ops[hvc->index - 1];
 170                 if ((last->type == MUNMAP) &&
 171                    (last->u.munmap.addr + last->u.mmap.len == addr)) {
 172                         last->u.munmap.len += len;
 173                         return 0;
 174                 }
 175         }
 176
 177         if (hvc->index == ARRAY_SIZE(hvc->ops)) {
 178                 ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
 179                 hvc->index = 0;
 180         }
 181
 182         hvc->ops[hvc->index++] = ((struct host_vm_op)
 183                                   { .type       = MUNMAP,
 184                                     .u = { .munmap = { .addr    = addr,
 185                                                        .len     = len } } });
 186         return ret;
 187 }
 188
 189 static int add_mprotect(unsigned long addr, unsigned long len,
 190                         unsigned int prot, struct host_vm_change *hvc)
 191 {
 192         struct host_vm_op *last;
 193         int ret = 0;
 194
 195         if (hvc->index != 0) {
 196                 last = &hvc->ops[hvc->index - 1];
 197                 if ((last->type == MPROTECT) &&
 198                    (last->u.mprotect.addr + last->u.mprotect.len == addr) &&
 199                    (last->u.mprotect.prot == prot)) {
 200                         last->u.mprotect.len += len;
 201                         return 0;
 202                 }
 203         }
 204
 205         if (hvc->index == ARRAY_SIZE(hvc->ops)) {
 206                 ret = do_ops(hvc, ARRAY_SIZE(hvc->ops), 0);
 207                 hvc->index = 0;
 208         }
 209
 210         hvc->ops[hvc->index++] = ((struct host_vm_op)
 211                                   { .type       = MPROTECT,
 212                                     .u = { .mprotect = { .addr  = addr,
 213                                                          .len   = len,
 214                                                          .prot  = prot } } });
 215         return ret;
 216 }
 217
 218 #define ADD_ROUND(n, inc) (((n) + (inc)) & ~((inc) - 1))
 219
 220 static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
 221                                    unsigned long end,
 222                                    struct host_vm_change *hvc)
 223 {
 224         pte_t *pte;
 225         int r, w, x, prot, ret = 0;
 226
 227         pte = pte_offset_kernel(pmd, addr);
 228         do {
 229                 if ((addr >= STUB_START) && (addr < STUB_END))
 230                         continue;
 231
 232                 r = pte_read(*pte);
 233                 w = pte_write(*pte);
 234                 x = pte_exec(*pte);
 235                 if (!pte_young(*pte)) {
 236                         r = 0;
 237                         w = 0;
 238                 } else if (!pte_dirty(*pte))
 239                         w = 0;
 240
 241                 prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
 242                         (x ? UM_PROT_EXEC : 0));
 243                 if (hvc->force || pte_newpage(*pte)) {
 244                         if (pte_present(*pte)) {
 245                                 if (pte_newpage(*pte))
 246                                         ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
 247                                                        PAGE_SIZE, prot, hvc);
 248                         } else
 249                                 ret = add_munmap(addr, PAGE_SIZE, hvc);
 250                 } else if (pte_newprot(*pte))
 251                         ret = add_mprotect(addr, PAGE_SIZE, prot, hvc);
 252                 *pte = pte_mkuptodate(*pte);
 253         } while (pte++, addr += PAGE_SIZE, ((addr < end) && !ret));
 254         return ret;
 255 }
 256
 257 static inline int update_pmd_range(pud_t *pud, unsigned long addr,
 258                                    unsigned long end,
 259                                    struct host_vm_change *hvc)
 260 {
 261         pmd_t *pmd;
 262         unsigned long next;
 263         int ret = 0;
 264
 265         pmd = pmd_offset(pud, addr);
 266         do {
 267                 next = pmd_addr_end(addr, end);
 268                 if (!pmd_present(*pmd)) {
 269                         if (hvc->force || pmd_newpage(*pmd)) {
 270                                 ret = add_munmap(addr, next - addr, hvc);
 271                                 pmd_mkuptodate(*pmd);
 272                         }
 273                 }
 274                 else ret = update_pte_range(pmd, addr, next, hvc);
 275         } while (pmd++, addr = next, ((addr < end) && !ret));
 276         return ret;
 277 }
 278
 279 static inline int update_pud_range(p4d_t *p4d, unsigned long addr,
 280                                    unsigned long end,
 281                                    struct host_vm_change *hvc)
 282 {
 283         pud_t *pud;
 284         unsigned long next;
 285         int ret = 0;
 286
 287         pud = pud_offset(p4d, addr);
 288         do {
 289                 next = pud_addr_end(addr, end);
 290                 if (!pud_present(*pud)) {
 291                         if (hvc->force || pud_newpage(*pud)) {
 292                                 ret = add_munmap(addr, next - addr, hvc);
 293                                 pud_mkuptodate(*pud);
 294                         }
 295                 }
 296                 else ret = update_pmd_range(pud, addr, next, hvc);
 297         } while (pud++, addr = next, ((addr < end) && !ret));
 298         return ret;
 299 }
 300
 301 static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
 302                                    unsigned long end,
 303                                    struct host_vm_change *hvc)
 304 {
 305         p4d_t *p4d;
 306         unsigned long next;
 307         int ret = 0;
 308
 309         p4d = p4d_offset(pgd, addr);
 310         do {
 311                 next = p4d_addr_end(addr, end);
 312                 if (!p4d_present(*p4d)) {
 313                         if (hvc->force || p4d_newpage(*p4d)) {
 314                                 ret = add_munmap(addr, next - addr, hvc);
 315                                 p4d_mkuptodate(*p4d);
 316                         }
 317                 } else
 318                         ret = update_pud_range(p4d, addr, next, hvc);
 319         } while (p4d++, addr = next, ((addr < end) && !ret));
 320         return ret;
 321 }
 322
 323 void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 324                       unsigned long end_addr, int force)
 325 {
 326         pgd_t *pgd;
 327         struct host_vm_change hvc;
 328         unsigned long addr = start_addr, next;
 329         int ret = 0, userspace = 1;
 330
 331         hvc = INIT_HVC(mm, force, userspace);
 332         pgd = pgd_offset(mm, addr);
 333         do {
 334                 next = pgd_addr_end(addr, end_addr);
 335                 if (!pgd_present(*pgd)) {
 336                         if (force || pgd_newpage(*pgd)) {
 337                                 ret = add_munmap(addr, next - addr, &hvc);
 338                                 pgd_mkuptodate(*pgd);
 339                         }
 340                 } else
 341                         ret = update_p4d_range(pgd, addr, next, &hvc);
 342         } while (pgd++, addr = next, ((addr < end_addr) && !ret));
 343
 344         if (!ret)
 345                 ret = do_ops(&hvc, hvc.index, 1);
 346
 347         /* This is not an else because ret is modified above */
 348         if (ret) {
 349                 printk(KERN_ERR "fix_range_common: failed, killing current "
 350                        "process: %d\n", task_tgid_vnr(current));
 351                 /* We are under mmap_sem, release it such that current can terminate */
 352                 mmap_write_unlock(current->mm);
 353                 force_sig(SIGKILL);
 354                 do_signal(&current->thread.regs);
 355         }
 356 }
 357
 358 static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
 359 {
 360         struct mm_struct *mm;
 361         pgd_t *pgd;
 362         p4d_t *p4d;
 363         pud_t *pud;
 364         pmd_t *pmd;
 365         pte_t *pte;
 366         unsigned long addr, last;
 367         int updated = 0, err = 0, force = 0, userspace = 0;
 368         struct host_vm_change hvc;
 369
 370         mm = &init_mm;
 371         hvc = INIT_HVC(mm, force, userspace);
 372         for (addr = start; addr < end;) {
 373                 pgd = pgd_offset(mm, addr);
 374                 if (!pgd_present(*pgd)) {
 375                         last = ADD_ROUND(addr, PGDIR_SIZE);
 376                         if (last > end)
 377                                 last = end;
 378                         if (pgd_newpage(*pgd)) {
 379                                 updated = 1;
 380                                 err = add_munmap(addr, last - addr, &hvc);
 381                                 if (err < 0)
 382                                         panic("munmap failed, errno = %d\n",
 383                                               -err);
 384                         }
 385                         addr = last;
 386                         continue;
 387                 }
 388
 389                 p4d = p4d_offset(pgd, addr);
 390                 if (!p4d_present(*p4d)) {
 391                         last = ADD_ROUND(addr, P4D_SIZE);
 392                         if (last > end)
 393                                 last = end;
 394                         if (p4d_newpage(*p4d)) {
 395                                 updated = 1;
 396                                 err = add_munmap(addr, last - addr, &hvc);
 397                                 if (err < 0)
 398                                         panic("munmap failed, errno = %d\n",
 399                                               -err);
 400                         }
 401                         addr = last;
 402                         continue;
 403                 }
 404
 405                 pud = pud_offset(p4d, addr);
 406                 if (!pud_present(*pud)) {
 407                         last = ADD_ROUND(addr, PUD_SIZE);
 408                         if (last > end)
 409                                 last = end;
 410                         if (pud_newpage(*pud)) {
 411                                 updated = 1;
 412                                 err = add_munmap(addr, last - addr, &hvc);
 413                                 if (err < 0)
 414                                         panic("munmap failed, errno = %d\n",
 415                                               -err);
 416                         }
 417                         addr = last;
 418                         continue;
 419                 }
 420
 421                 pmd = pmd_offset(pud, addr);
 422                 if (!pmd_present(*pmd)) {
 423                         last = ADD_ROUND(addr, PMD_SIZE);
 424                         if (last > end)
 425                                 last = end;
 426                         if (pmd_newpage(*pmd)) {
 427                                 updated = 1;
 428                                 err = add_munmap(addr, last - addr, &hvc);
 429                                 if (err < 0)
 430                                         panic("munmap failed, errno = %d\n",
 431                                               -err);
 432                         }
 433                         addr = last;
 434                         continue;
 435                 }
 436
 437                 pte = pte_offset_kernel(pmd, addr);
 438                 if (!pte_present(*pte) || pte_newpage(*pte)) {
 439                         updated = 1;
 440                         err = add_munmap(addr, PAGE_SIZE, &hvc);
 441                         if (err < 0)
 442                                 panic("munmap failed, errno = %d\n",
 443                                       -err);
 444                         if (pte_present(*pte))
 445                                 err = add_mmap(addr, pte_val(*pte) & PAGE_MASK,
 446                                                PAGE_SIZE, 0, &hvc);
 447                 }
 448                 else if (pte_newprot(*pte)) {
 449                         updated = 1;
 450                         err = add_mprotect(addr, PAGE_SIZE, 0, &hvc);
 451                 }
 452                 addr += PAGE_SIZE;
 453         }
 454         if (!err)
 455                 err = do_ops(&hvc, hvc.index, 1);
 456
 457         if (err < 0)
 458                 panic("flush_tlb_kernel failed, errno = %d\n", err);
 459         return updated;
 460 }
 461
 462 void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 463 {
 464         pgd_t *pgd;
 465         p4d_t *p4d;
 466         pud_t *pud;
 467         pmd_t *pmd;
 468         pte_t *pte;
 469         struct mm_struct *mm = vma->vm_mm;
 470         void *flush = NULL;
 471         int r, w, x, prot, err = 0;
 472         struct mm_id *mm_id;
 473
 474         address &= PAGE_MASK;
 475         pgd = pgd_offset(mm, address);
 476         if (!pgd_present(*pgd))
 477                 goto kill;
 478
 479         p4d = p4d_offset(pgd, address);
 480         if (!p4d_present(*p4d))
 481                 goto kill;
 482
 483         pud = pud_offset(p4d, address);
 484         if (!pud_present(*pud))
 485                 goto kill;
 486
 487         pmd = pmd_offset(pud, address);
 488         if (!pmd_present(*pmd))
 489                 goto kill;
 490
 491         pte = pte_offset_kernel(pmd, address);
 492
 493         r = pte_read(*pte);
 494         w = pte_write(*pte);
 495         x = pte_exec(*pte);
 496         if (!pte_young(*pte)) {
 497                 r = 0;
 498                 w = 0;
 499         } else if (!pte_dirty(*pte)) {
 500                 w = 0;
 501         }
 502
 503         mm_id = &mm->context.id;
 504         prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
 505                 (x ? UM_PROT_EXEC : 0));
 506         if (pte_newpage(*pte)) {
 507                 if (pte_present(*pte)) {
 508                         unsigned long long offset;
 509                         int fd;
 510
 511                         fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
 512                         err = map(mm_id, address, PAGE_SIZE, prot, fd, offset,
 513                                   1, &flush);
 514                 }
 515                 else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
 516         }
 517         else if (pte_newprot(*pte))
 518                 err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
 519
 520         if (err) {
 521                 if (err == -ENOMEM)
 522                         report_enomem();
 523
 524                 goto kill;
 525         }
 526
 527         *pte = pte_mkuptodate(*pte);
 528
 529         return;
 530
 531 kill:
 532         printk(KERN_ERR "Failed to flush page for address 0x%lx\n", address);
 533         force_sig(SIGKILL);
 534 }
 535
 536 void flush_tlb_all(void)
 537 {
 538         /*
 539          * Don't bother flushing if this address space is about to be
 540          * destroyed.
 541          */
 542         if (atomic_read(&current->mm->mm_users) == 0)
 543                 return;
 544
 545         flush_tlb_mm(current->mm);
 546 }
 547
 548 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 549 {
 550         flush_tlb_kernel_range_common(start, end);
 551 }
 552
 553 void flush_tlb_kernel_vm(void)
 554 {
 555         flush_tlb_kernel_range_common(start_vm, end_vm);
 556 }
 557
 558 void __flush_tlb_one(unsigned long addr)
 559 {
 560         flush_tlb_kernel_range_common(addr, addr + PAGE_SIZE);
 561 }
 562
 563 static void fix_range(struct mm_struct *mm, unsigned long start_addr,
 564                       unsigned long end_addr, int force)
 565 {
 566         /*
 567          * Don't bother flushing if this address space is about to be
 568          * destroyed.
 569          */
 570         if (atomic_read(&mm->mm_users) == 0)
 571                 return;
 572
 573         fix_range_common(mm, start_addr, end_addr, force);
 574 }
 575
 576 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 577                      unsigned long end)
 578 {
 579         if (vma->vm_mm == NULL)
 580                 flush_tlb_kernel_range_common(start, end);
 581         else fix_range(vma->vm_mm, start, end, 0);
 582 }
 583 EXPORT_SYMBOL(flush_tlb_range);
 584
 585 void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 586                         unsigned long end)
 587 {
 588         fix_range(mm, start, end, 0);
 589 }
 590
 591 void flush_tlb_mm(struct mm_struct *mm)
 592 {
 593         struct vm_area_struct *vma = mm->mmap;
 594
 595         while (vma != NULL) {
 596                 fix_range(mm, vma->vm_start, vma->vm_end, 0);
 597                 vma = vma->vm_next;
 598         }
 599 }
 600
 601 void force_flush_all(void)
 602 {
 603         struct mm_struct *mm = current->mm;
 604         struct vm_area_struct *vma = mm->mmap;
 605
 606         while (vma != NULL) {
 607                 fix_range(mm, vma->vm_start, vma->vm_end, 1);
 608                 vma = vma->vm_next;
 609         }
 610 }