arch/arm64/kernel/hibernate.c

   1 /*:
   2  * Hibernate support specific for ARM64
   3  *
   4  * Derived from work on ARM hibernation support by:
   5  *
   6  * Ubuntu project, hibernation support for mach-dove
   7  * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
   8  * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
   9  *  https://lkml.org/lkml/2010/6/18/4
  10  *  https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html
  11  *  https://patchwork.kernel.org/patch/96442/
  12  *
  13  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  14  *
  15  * License terms: GNU General Public License (GPL) version 2
  16  */
  17 #define pr_fmt(x) "hibernate: " x
  18 #include <linux/kvm_host.h>
  19 #include <linux/mm.h>
  20 #include <linux/notifier.h>
  21 #include <linux/pm.h>
  22 #include <linux/sched.h>
  23 #include <linux/suspend.h>
  24 #include <linux/utsname.h>
  25 #include <linux/version.h>
  26
  27 #include <asm/barrier.h>
  28 #include <asm/cacheflush.h>
  29 #include <asm/irqflags.h>
  30 #include <asm/memory.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/pgalloc.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/pgtable-hwdef.h>
  35 #include <asm/sections.h>
  36 #include <asm/smp.h>
  37 #include <asm/suspend.h>
  38 #include <asm/sysreg.h>
  39 #include <asm/virt.h>
  40
  41 /*
  42  * Hibernate core relies on this value being 0 on resume, and marks it
  43  * __nosavedata assuming it will keep the resume kernel's '0' value. This
  44  * doesn't happen with either KASLR.
  45  *
  46  * defined as "__visible int in_suspend __nosavedata" in
  47  * kernel/power/hibernate.c
  48  */
  49 extern int in_suspend;
  50
  51 /* Find a symbols alias in the linear map */
  52 #define LMADDR(x)       phys_to_virt(virt_to_phys(x))
  53
  54 /* Do we need to reset el2? */
  55 #define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())
  56
  57 /*
  58  * Start/end of the hibernate exit code, this must be copied to a 'safe'
  59  * location in memory, and executed from there.
  60  */
  61 extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];
  62
  63 /* temporary el2 vectors in the __hibernate_exit_text section. */
  64 extern char hibernate_el2_vectors[];
  65
  66 /* hyp-stub vectors, used to restore el2 during resume from hibernate. */
  67 extern char __hyp_stub_vectors[];
  68
  69 /*
  70  * Values that may not change over hibernate/resume. We put the build number
  71  * and date in here so that we guarantee not to resume with a different
  72  * kernel.
  73  */
  74 struct arch_hibernate_hdr_invariants {
  75         char            uts_version[__NEW_UTS_LEN + 1];
  76 };
  77
  78 /* These values need to be know across a hibernate/restore. */
  79 static struct arch_hibernate_hdr {
  80         struct arch_hibernate_hdr_invariants invariants;
  81
  82         /* These are needed to find the relocated kernel if built with kaslr */
  83         phys_addr_t     ttbr1_el1;
  84         void            (*reenter_kernel)(void);
  85
  86         /*
  87          * We need to know where the __hyp_stub_vectors are after restore to
  88          * re-configure el2.
  89          */
  90         phys_addr_t     __hyp_stub_vectors;
  91 } resume_hdr;
  92
  93 static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
  94 {
  95         memset(i, 0, sizeof(*i));
  96         memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
  97 }
  98
  99 int pfn_is_nosave(unsigned long pfn)
 100 {
 101         unsigned long nosave_begin_pfn = virt_to_pfn(&__nosave_begin);
 102         unsigned long nosave_end_pfn = virt_to_pfn(&__nosave_end - 1);
 103
 104         return (pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn);
 105 }
 106
 107 void notrace save_processor_state(void)
 108 {
 109         WARN_ON(num_online_cpus() != 1);
 110 }
 111
 112 void notrace restore_processor_state(void)
 113 {
 114 }
 115
 116 int arch_hibernation_header_save(void *addr, unsigned int max_size)
 117 {
 118         struct arch_hibernate_hdr *hdr = addr;
 119
 120         if (max_size < sizeof(*hdr))
 121                 return -EOVERFLOW;
 122
 123         arch_hdr_invariants(&hdr->invariants);
 124         hdr->ttbr1_el1          = virt_to_phys(swapper_pg_dir);
 125         hdr->reenter_kernel     = _cpu_resume;
 126
 127         /* We can't use __hyp_get_vectors() because kvm may still be loaded */
 128         if (el2_reset_needed())
 129                 hdr->__hyp_stub_vectors = virt_to_phys(__hyp_stub_vectors);
 130         else
 131                 hdr->__hyp_stub_vectors = 0;
 132
 133         return 0;
 134 }
 135 EXPORT_SYMBOL(arch_hibernation_header_save);
 136
 137 int arch_hibernation_header_restore(void *addr)
 138 {
 139         struct arch_hibernate_hdr_invariants invariants;
 140         struct arch_hibernate_hdr *hdr = addr;
 141
 142         arch_hdr_invariants(&invariants);
 143         if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
 144                 pr_crit("Hibernate image not generated by this kernel!\n");
 145                 return -EINVAL;
 146         }
 147
 148         resume_hdr = *hdr;
 149
 150         return 0;
 151 }
 152 EXPORT_SYMBOL(arch_hibernation_header_restore);
 153
 154 /*
 155  * Copies length bytes, starting at src_start into an new page,
 156  * perform cache maintentance, then maps it at the specified address low
 157  * address as executable.
 158  *
 159  * This is used by hibernate to copy the code it needs to execute when
 160  * overwriting the kernel text. This function generates a new set of page
 161  * tables, which it loads into ttbr0.
 162  *
 163  * Length is provided as we probably only want 4K of data, even on a 64K
 164  * page system.
 165  */
 166 static int create_safe_exec_page(void *src_start, size_t length,
 167                                  unsigned long dst_addr,
 168                                  phys_addr_t *phys_dst_addr,
 169                                  void *(*allocator)(gfp_t mask),
 170                                  gfp_t mask)
 171 {
 172         int rc = 0;
 173         pgd_t *pgd;
 174         pud_t *pud;
 175         pmd_t *pmd;
 176         pte_t *pte;
 177         unsigned long dst = (unsigned long)allocator(mask);
 178
 179         if (!dst) {
 180                 rc = -ENOMEM;
 181                 goto out;
 182         }
 183
 184         memcpy((void *)dst, src_start, length);
 185         flush_icache_range(dst, dst + length);
 186
 187         pgd = pgd_offset_raw(allocator(mask), dst_addr);
 188         if (pgd_none(*pgd)) {
 189                 pud = allocator(mask);
 190                 if (!pud) {
 191                         rc = -ENOMEM;
 192                         goto out;
 193                 }
 194                 pgd_populate(&init_mm, pgd, pud);
 195         }
 196
 197         pud = pud_offset(pgd, dst_addr);
 198         if (pud_none(*pud)) {
 199                 pmd = allocator(mask);
 200                 if (!pmd) {
 201                         rc = -ENOMEM;
 202                         goto out;
 203                 }
 204                 pud_populate(&init_mm, pud, pmd);
 205         }
 206
 207         pmd = pmd_offset(pud, dst_addr);
 208         if (pmd_none(*pmd)) {
 209                 pte = allocator(mask);
 210                 if (!pte) {
 211                         rc = -ENOMEM;
 212                         goto out;
 213                 }
 214                 pmd_populate_kernel(&init_mm, pmd, pte);
 215         }
 216
 217         pte = pte_offset_kernel(pmd, dst_addr);
 218         set_pte(pte, __pte(virt_to_phys((void *)dst) |
 219                          pgprot_val(PAGE_KERNEL_EXEC)));
 220
 221         /*
 222          * Load our new page tables. A strict BBM approach requires that we
 223          * ensure that TLBs are free of any entries that may overlap with the
 224          * global mappings we are about to install.
 225          *
 226          * For a real hibernate/resume cycle TTBR0 currently points to a zero
 227          * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI
 228          * runtime services), while for a userspace-driven test_resume cycle it
 229          * points to userspace page tables (and we must point it at a zero page
 230          * ourselves). Elsewhere we only (un)install the idmap with preemption
 231          * disabled, so T0SZ should be as required regardless.
 232          */
 233         cpu_set_reserved_ttbr0();
 234         local_flush_tlb_all();
 235         write_sysreg(virt_to_phys(pgd), ttbr0_el1);
 236         isb();
 237
 238         *phys_dst_addr = virt_to_phys((void *)dst);
 239
 240 out:
 241         return rc;
 242 }
 243
 244
 245 int swsusp_arch_suspend(void)
 246 {
 247         int ret = 0;
 248         unsigned long flags;
 249         struct sleep_stack_data state;
 250
 251         if (cpus_are_stuck_in_kernel()) {
 252                 pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
 253                 return -EBUSY;
 254         }
 255
 256         local_dbg_save(flags);
 257
 258         if (__cpu_suspend_enter(&state)) {
 259                 ret = swsusp_save();
 260         } else {
 261                 /* Clean kernel to PoC for secondary core startup */
 262                 __flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);
 263
 264                 /*
 265                  * Tell the hibernation core that we've just restored
 266                  * the memory
 267                  */
 268                 in_suspend = 0;
 269
 270                 __cpu_suspend_exit();
 271         }
 272
 273         local_dbg_restore(flags);
 274
 275         return ret;
 276 }
 277
 278 static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
 279                     unsigned long end)
 280 {
 281         pte_t *src_pte;
 282         pte_t *dst_pte;
 283         unsigned long addr = start;
 284
 285         dst_pte = (pte_t *)get_safe_page(GFP_ATOMIC);
 286         if (!dst_pte)
 287                 return -ENOMEM;
 288         pmd_populate_kernel(&init_mm, dst_pmd, dst_pte);
 289         dst_pte = pte_offset_kernel(dst_pmd, start);
 290
 291         src_pte = pte_offset_kernel(src_pmd, start);
 292         do {
 293                 if (!pte_none(*src_pte))
 294                         /*
 295                          * Resume will overwrite areas that may be marked
 296                          * read only (code, rodata). Clear the RDONLY bit from
 297                          * the temporary mappings we use during restore.
 298                          */
 299                         set_pte(dst_pte, __pte(pte_val(*src_pte) & ~PTE_RDONLY));
 300         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 301
 302         return 0;
 303 }
 304
 305 static int copy_pmd(pud_t *dst_pud, pud_t *src_pud, unsigned long start,
 306                     unsigned long end)
 307 {
 308         pmd_t *src_pmd;
 309         pmd_t *dst_pmd;
 310         unsigned long next;
 311         unsigned long addr = start;
 312
 313         if (pud_none(*dst_pud)) {
 314                 dst_pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
 315                 if (!dst_pmd)
 316                         return -ENOMEM;
 317                 pud_populate(&init_mm, dst_pud, dst_pmd);
 318         }
 319         dst_pmd = pmd_offset(dst_pud, start);
 320
 321         src_pmd = pmd_offset(src_pud, start);
 322         do {
 323                 next = pmd_addr_end(addr, end);
 324                 if (pmd_none(*src_pmd))
 325                         continue;
 326                 if (pmd_table(*src_pmd)) {
 327                         if (copy_pte(dst_pmd, src_pmd, addr, next))
 328                                 return -ENOMEM;
 329                 } else {
 330                         set_pmd(dst_pmd,
 331                                 __pmd(pmd_val(*src_pmd) & ~PMD_SECT_RDONLY));
 332                 }
 333         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
 334
 335         return 0;
 336 }
 337
 338 static int copy_pud(pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long start,
 339                     unsigned long end)
 340 {
 341         pud_t *dst_pud;
 342         pud_t *src_pud;
 343         unsigned long next;
 344         unsigned long addr = start;
 345
 346         if (pgd_none(*dst_pgd)) {
 347                 dst_pud = (pud_t *)get_safe_page(GFP_ATOMIC);
 348                 if (!dst_pud)
 349                         return -ENOMEM;
 350                 pgd_populate(&init_mm, dst_pgd, dst_pud);
 351         }
 352         dst_pud = pud_offset(dst_pgd, start);
 353
 354         src_pud = pud_offset(src_pgd, start);
 355         do {
 356                 next = pud_addr_end(addr, end);
 357                 if (pud_none(*src_pud))
 358                         continue;
 359                 if (pud_table(*(src_pud))) {
 360                         if (copy_pmd(dst_pud, src_pud, addr, next))
 361                                 return -ENOMEM;
 362                 } else {
 363                         set_pud(dst_pud,
 364                                 __pud(pud_val(*src_pud) & ~PMD_SECT_RDONLY));
 365                 }
 366         } while (dst_pud++, src_pud++, addr = next, addr != end);
 367
 368         return 0;
 369 }
 370
 371 static int copy_page_tables(pgd_t *dst_pgd, unsigned long start,
 372                             unsigned long end)
 373 {
 374         unsigned long next;
 375         unsigned long addr = start;
 376         pgd_t *src_pgd = pgd_offset_k(start);
 377
 378         dst_pgd = pgd_offset_raw(dst_pgd, start);
 379         do {
 380                 next = pgd_addr_end(addr, end);
 381                 if (pgd_none(*src_pgd))
 382                         continue;
 383                 if (copy_pud(dst_pgd, src_pgd, addr, next))
 384                         return -ENOMEM;
 385         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
 386
 387         return 0;
 388 }
 389
 390 /*
 391  * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
 392  *
 393  * Memory allocated by get_safe_page() will be dealt with by the hibernate code,
 394  * we don't need to free it here.
 395  */
 396 int swsusp_arch_resume(void)
 397 {
 398         int rc = 0;
 399         void *zero_page;
 400         size_t exit_size;
 401         pgd_t *tmp_pg_dir;
 402         void *lm_restore_pblist;
 403         phys_addr_t phys_hibernate_exit;
 404         void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
 405                                           void *, phys_addr_t, phys_addr_t);
 406
 407         /*
 408          * Restoring the memory image will overwrite the ttbr1 page tables.
 409          * Create a second copy of just the linear map, and use this when
 410          * restoring.
 411          */
 412         tmp_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
 413         if (!tmp_pg_dir) {
 414                 pr_err("Failed to allocate memory for temporary page tables.");
 415                 rc = -ENOMEM;
 416                 goto out;
 417         }
 418         rc = copy_page_tables(tmp_pg_dir, PAGE_OFFSET, 0);
 419         if (rc)
 420                 goto out;
 421
 422         /*
 423          * Since we only copied the linear map, we need to find restore_pblist's
 424          * linear map address.
 425          */
 426         lm_restore_pblist = LMADDR(restore_pblist);
 427
 428         /*
 429          * We need a zero page that is zero before & after resume in order to
 430          * to break before make on the ttbr1 page tables.
 431          */
 432         zero_page = (void *)get_safe_page(GFP_ATOMIC);
 433         if (!zero_page) {
 434                 pr_err("Failed to allocate zero page.");
 435                 rc = -ENOMEM;
 436                 goto out;
 437         }
 438
 439         /*
 440          * Locate the exit code in the bottom-but-one page, so that *NULL
 441          * still has disastrous affects.
 442          */
 443         hibernate_exit = (void *)PAGE_SIZE;
 444         exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
 445         /*
 446          * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
 447          * a new set of ttbr0 page tables and load them.
 448          */
 449         rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
 450                                    (unsigned long)hibernate_exit,
 451                                    &phys_hibernate_exit,
 452                                    (void *)get_safe_page, GFP_ATOMIC);
 453         if (rc) {
 454                 pr_err("Failed to create safe executable page for hibernate_exit code.");
 455                 goto out;
 456         }
 457
 458         /*
 459          * The hibernate exit text contains a set of el2 vectors, that will
 460          * be executed at el2 with the mmu off in order to reload hyp-stub.
 461          */
 462         __flush_dcache_area(hibernate_exit, exit_size);
 463
 464         /*
 465          * KASLR will cause the el2 vectors to be in a different location in
 466          * the resumed kernel. Load hibernate's temporary copy into el2.
 467          *
 468          * We can skip this step if we booted at EL1, or are running with VHE.
 469          */
 470         if (el2_reset_needed()) {
 471                 phys_addr_t el2_vectors = phys_hibernate_exit;  /* base */
 472                 el2_vectors += hibernate_el2_vectors -
 473                                __hibernate_exit_text_start;     /* offset */
 474
 475                 __hyp_set_vectors(el2_vectors);
 476         }
 477
 478         hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
 479                        resume_hdr.reenter_kernel, lm_restore_pblist,
 480                        resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));
 481
 482 out:
 483         return rc;
 484 }
 485
 486 static int check_boot_cpu_online_pm_callback(struct notifier_block *nb,
 487                                              unsigned long action, void *ptr)
 488 {
 489         if (action == PM_HIBERNATION_PREPARE &&
 490              cpumask_first(cpu_online_mask) != 0) {
 491                 pr_warn("CPU0 is offline.\n");
 492                 return notifier_from_errno(-ENODEV);
 493         }
 494
 495         return NOTIFY_OK;
 496 }
 497
 498 static int __init check_boot_cpu_online_init(void)
 499 {
 500         /*
 501          * Set this pm_notifier callback with a lower priority than
 502          * cpu_hotplug_pm_callback, so that cpu_hotplug_pm_callback will be
 503          * called earlier to disable cpu hotplug before the cpu online check.
 504          */
 505         pm_notifier(check_boot_cpu_online_pm_callback, -INT_MAX);
 506
 507         return 0;
 508 }
 509 core_initcall(check_boot_cpu_online_init);