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