arch/arm64/kernel/hibernate.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*:
   3  * Hibernate support specific for ARM64
   4  *
   5  * Derived from work on ARM hibernation support by:
   6  *
   7  * Ubuntu project, hibernation support for mach-dove
   8  * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
   9  * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
  10  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  11  */
  12 #define pr_fmt(x) "hibernate: " x
  13 #include <linux/cpu.h>
  14 #include <linux/kvm_host.h>
  15 #include <linux/pm.h>
  16 #include <linux/sched.h>
  17 #include <linux/suspend.h>
  18 #include <linux/utsname.h>
  19
  20 #include <asm/barrier.h>
  21 #include <asm/cacheflush.h>
  22 #include <asm/cputype.h>
  23 #include <asm/daifflags.h>
  24 #include <asm/irqflags.h>
  25 #include <asm/kexec.h>
  26 #include <asm/memory.h>
  27 #include <asm/mmu_context.h>
  28 #include <asm/mte.h>
  29 #include <asm/sections.h>
  30 #include <asm/smp.h>
  31 #include <asm/smp_plat.h>
  32 #include <asm/suspend.h>
  33 #include <asm/sysreg.h>
  34 #include <asm/trans_pgd.h>
  35 #include <asm/virt.h>
  36
  37 /*
  38  * Hibernate core relies on this value being 0 on resume, and marks it
  39  * __nosavedata assuming it will keep the resume kernel's '0' value. This
  40  * doesn't happen with either KASLR.
  41  *
  42  * defined as "__visible int in_suspend __nosavedata" in
  43  * kernel/power/hibernate.c
  44  */
  45 extern int in_suspend;
  46
  47 /* Do we need to reset el2? */
  48 #define el2_reset_needed() (is_hyp_nvhe())
  49
  50 /* hyp-stub vectors, used to restore el2 during resume from hibernate. */
  51 extern char __hyp_stub_vectors[];
  52
  53 /*
  54  * The logical cpu number we should resume on, initialised to a non-cpu
  55  * number.
  56  */
  57 static int sleep_cpu = -EINVAL;
  58
  59 /*
  60  * Values that may not change over hibernate/resume. We put the build number
  61  * and date in here so that we guarantee not to resume with a different
  62  * kernel.
  63  */
  64 struct arch_hibernate_hdr_invariants {
  65         char            uts_version[__NEW_UTS_LEN + 1];
  66 };
  67
  68 /* These values need to be know across a hibernate/restore. */
  69 static struct arch_hibernate_hdr {
  70         struct arch_hibernate_hdr_invariants invariants;
  71
  72         /* These are needed to find the relocated kernel if built with kaslr */
  73         phys_addr_t     ttbr1_el1;
  74         void            (*reenter_kernel)(void);
  75
  76         /*
  77          * We need to know where the __hyp_stub_vectors are after restore to
  78          * re-configure el2.
  79          */
  80         phys_addr_t     __hyp_stub_vectors;
  81
  82         u64             sleep_cpu_mpidr;
  83 } resume_hdr;
  84
  85 static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
  86 {
  87         memset(i, 0, sizeof(*i));
  88         memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
  89 }
  90
  91 int pfn_is_nosave(unsigned long pfn)
  92 {
  93         unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
  94         unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
  95
  96         return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
  97                 crash_is_nosave(pfn);
  98 }
  99
 100 void notrace save_processor_state(void)
 101 {
 102 }
 103
 104 void notrace restore_processor_state(void)
 105 {
 106 }
 107
 108 int arch_hibernation_header_save(void *addr, unsigned int max_size)
 109 {
 110         struct arch_hibernate_hdr *hdr = addr;
 111
 112         if (max_size < sizeof(*hdr))
 113                 return -EOVERFLOW;
 114
 115         arch_hdr_invariants(&hdr->invariants);
 116         hdr->ttbr1_el1          = __pa_symbol(swapper_pg_dir);
 117         hdr->reenter_kernel     = _cpu_resume;
 118
 119         /* We can't use __hyp_get_vectors() because kvm may still be loaded */
 120         if (el2_reset_needed())
 121                 hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
 122         else
 123                 hdr->__hyp_stub_vectors = 0;
 124
 125         /* Save the mpidr of the cpu we called cpu_suspend() on... */
 126         if (sleep_cpu < 0) {
 127                 pr_err("Failing to hibernate on an unknown CPU.\n");
 128                 return -ENODEV;
 129         }
 130         hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
 131         pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
 132                 hdr->sleep_cpu_mpidr);
 133
 134         return 0;
 135 }
 136 EXPORT_SYMBOL(arch_hibernation_header_save);
 137
 138 int arch_hibernation_header_restore(void *addr)
 139 {
 140         int ret;
 141         struct arch_hibernate_hdr_invariants invariants;
 142         struct arch_hibernate_hdr *hdr = addr;
 143
 144         arch_hdr_invariants(&invariants);
 145         if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
 146                 pr_crit("Hibernate image not generated by this kernel!\n");
 147                 return -EINVAL;
 148         }
 149
 150         sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
 151         pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
 152                 hdr->sleep_cpu_mpidr);
 153         if (sleep_cpu < 0) {
 154                 pr_crit("Hibernated on a CPU not known to this kernel!\n");
 155                 sleep_cpu = -EINVAL;
 156                 return -EINVAL;
 157         }
 158
 159         ret = bringup_hibernate_cpu(sleep_cpu);
 160         if (ret) {
 161                 sleep_cpu = -EINVAL;
 162                 return ret;
 163         }
 164
 165         resume_hdr = *hdr;
 166
 167         return 0;
 168 }
 169 EXPORT_SYMBOL(arch_hibernation_header_restore);
 170
 171 static void *hibernate_page_alloc(void *arg)
 172 {
 173         return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
 174 }
 175
 176 /*
 177  * Copies length bytes, starting at src_start into an new page,
 178  * perform cache maintenance, then maps it at the specified address low
 179  * address as executable.
 180  *
 181  * This is used by hibernate to copy the code it needs to execute when
 182  * overwriting the kernel text. This function generates a new set of page
 183  * tables, which it loads into ttbr0.
 184  *
 185  * Length is provided as we probably only want 4K of data, even on a 64K
 186  * page system.
 187  */
 188 static int create_safe_exec_page(void *src_start, size_t length,
 189                                  phys_addr_t *phys_dst_addr)
 190 {
 191         struct trans_pgd_info trans_info = {
 192                 .trans_alloc_page       = hibernate_page_alloc,
 193                 .trans_alloc_arg        = (__force void *)GFP_ATOMIC,
 194         };
 195
 196         void *page = (void *)get_safe_page(GFP_ATOMIC);
 197         phys_addr_t trans_ttbr0;
 198         unsigned long t0sz;
 199         int rc;
 200
 201         if (!page)
 202                 return -ENOMEM;
 203
 204         memcpy(page, src_start, length);
 205         caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
 206         rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
 207         if (rc)
 208                 return rc;
 209
 210         cpu_install_ttbr0(trans_ttbr0, t0sz);
 211         *phys_dst_addr = virt_to_phys(page);
 212
 213         return 0;
 214 }
 215
 216 #ifdef CONFIG_ARM64_MTE
 217
 218 static DEFINE_XARRAY(mte_pages);
 219
 220 static int save_tags(struct page *page, unsigned long pfn)
 221 {
 222         void *tag_storage, *ret;
 223
 224         tag_storage = mte_allocate_tag_storage();
 225         if (!tag_storage)
 226                 return -ENOMEM;
 227
 228         mte_save_page_tags(page_address(page), tag_storage);
 229
 230         ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
 231         if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
 232                 mte_free_tag_storage(tag_storage);
 233                 return xa_err(ret);
 234         } else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
 235                 mte_free_tag_storage(ret);
 236         }
 237
 238         return 0;
 239 }
 240
 241 static void swsusp_mte_free_storage(void)
 242 {
 243         XA_STATE(xa_state, &mte_pages, 0);
 244         void *tags;
 245
 246         xa_lock(&mte_pages);
 247         xas_for_each(&xa_state, tags, ULONG_MAX) {
 248                 mte_free_tag_storage(tags);
 249         }
 250         xa_unlock(&mte_pages);
 251
 252         xa_destroy(&mte_pages);
 253 }
 254
 255 static int swsusp_mte_save_tags(void)
 256 {
 257         struct zone *zone;
 258         unsigned long pfn, max_zone_pfn;
 259         int ret = 0;
 260         int n = 0;
 261
 262         if (!system_supports_mte())
 263                 return 0;
 264
 265         for_each_populated_zone(zone) {
 266                 max_zone_pfn = zone_end_pfn(zone);
 267                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
 268                         struct page *page = pfn_to_online_page(pfn);
 269
 270                         if (!page)
 271                                 continue;
 272
 273                         if (!page_mte_tagged(page))
 274                                 continue;
 275
 276                         ret = save_tags(page, pfn);
 277                         if (ret) {
 278                                 swsusp_mte_free_storage();
 279                                 goto out;
 280                         }
 281
 282                         n++;
 283                 }
 284         }
 285         pr_info("Saved %d MTE pages\n", n);
 286
 287 out:
 288         return ret;
 289 }
 290
 291 static void swsusp_mte_restore_tags(void)
 292 {
 293         XA_STATE(xa_state, &mte_pages, 0);
 294         int n = 0;
 295         void *tags;
 296
 297         xa_lock(&mte_pages);
 298         xas_for_each(&xa_state, tags, ULONG_MAX) {
 299                 unsigned long pfn = xa_state.xa_index;
 300                 struct page *page = pfn_to_online_page(pfn);
 301
 302                 mte_restore_page_tags(page_address(page), tags);
 303
 304                 mte_free_tag_storage(tags);
 305                 n++;
 306         }
 307         xa_unlock(&mte_pages);
 308
 309         pr_info("Restored %d MTE pages\n", n);
 310
 311         xa_destroy(&mte_pages);
 312 }
 313
 314 #else   /* CONFIG_ARM64_MTE */
 315
 316 static int swsusp_mte_save_tags(void)
 317 {
 318         return 0;
 319 }
 320
 321 static void swsusp_mte_restore_tags(void)
 322 {
 323 }
 324
 325 #endif  /* CONFIG_ARM64_MTE */
 326
 327 int swsusp_arch_suspend(void)
 328 {
 329         int ret = 0;
 330         unsigned long flags;
 331         struct sleep_stack_data state;
 332
 333         if (cpus_are_stuck_in_kernel()) {
 334                 pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
 335                 return -EBUSY;
 336         }
 337
 338         flags = local_daif_save();
 339
 340         if (__cpu_suspend_enter(&state)) {
 341                 /* make the crash dump kernel image visible/saveable */
 342                 crash_prepare_suspend();
 343
 344                 ret = swsusp_mte_save_tags();
 345                 if (ret)
 346                         return ret;
 347
 348                 sleep_cpu = smp_processor_id();
 349                 ret = swsusp_save();
 350         } else {
 351                 /* Clean kernel core startup/idle code to PoC*/
 352                 dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
 353                                     (unsigned long)__mmuoff_data_end);
 354                 dcache_clean_inval_poc((unsigned long)__idmap_text_start,
 355                                     (unsigned long)__idmap_text_end);
 356
 357                 /* Clean kvm setup code to PoC? */
 358                 if (el2_reset_needed()) {
 359                         dcache_clean_inval_poc(
 360                                 (unsigned long)__hyp_idmap_text_start,
 361                                 (unsigned long)__hyp_idmap_text_end);
 362                         dcache_clean_inval_poc((unsigned long)__hyp_text_start,
 363                                             (unsigned long)__hyp_text_end);
 364                 }
 365
 366                 swsusp_mte_restore_tags();
 367
 368                 /* make the crash dump kernel image protected again */
 369                 crash_post_resume();
 370
 371                 /*
 372                  * Tell the hibernation core that we've just restored
 373                  * the memory
 374                  */
 375                 in_suspend = 0;
 376
 377                 sleep_cpu = -EINVAL;
 378                 __cpu_suspend_exit();
 379
 380                 /*
 381                  * Just in case the boot kernel did turn the SSBD
 382                  * mitigation off behind our back, let's set the state
 383                  * to what we expect it to be.
 384                  */
 385                 spectre_v4_enable_mitigation(NULL);
 386         }
 387
 388         local_daif_restore(flags);
 389
 390         return ret;
 391 }
 392
 393 /*
 394  * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
 395  *
 396  * Memory allocated by get_safe_page() will be dealt with by the hibernate code,
 397  * we don't need to free it here.
 398  */
 399 int swsusp_arch_resume(void)
 400 {
 401         int rc;
 402         void *zero_page;
 403         size_t exit_size;
 404         pgd_t *tmp_pg_dir;
 405         phys_addr_t el2_vectors;
 406         void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
 407                                           void *, phys_addr_t, phys_addr_t);
 408         struct trans_pgd_info trans_info = {
 409                 .trans_alloc_page       = hibernate_page_alloc,
 410                 .trans_alloc_arg        = (void *)GFP_ATOMIC,
 411         };
 412
 413         /*
 414          * Restoring the memory image will overwrite the ttbr1 page tables.
 415          * Create a second copy of just the linear map, and use this when
 416          * restoring.
 417          */
 418         rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
 419                                    PAGE_END);
 420         if (rc)
 421                 return rc;
 422
 423         /*
 424          * We need a zero page that is zero before & after resume in order
 425          * to break before make on the ttbr1 page tables.
 426          */
 427         zero_page = (void *)get_safe_page(GFP_ATOMIC);
 428         if (!zero_page) {
 429                 pr_err("Failed to allocate zero page.\n");
 430                 return -ENOMEM;
 431         }
 432
 433         if (el2_reset_needed()) {
 434                 rc = trans_pgd_copy_el2_vectors(&trans_info, &el2_vectors);
 435                 if (rc) {
 436                         pr_err("Failed to setup el2 vectors\n");
 437                         return rc;
 438                 }
 439         }
 440
 441         exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
 442         /*
 443          * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
 444          * a new set of ttbr0 page tables and load them.
 445          */
 446         rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
 447                                    (phys_addr_t *)&hibernate_exit);
 448         if (rc) {
 449                 pr_err("Failed to create safe executable page for hibernate_exit code.\n");
 450                 return rc;
 451         }
 452
 453         /*
 454          * KASLR will cause the el2 vectors to be in a different location in
 455          * the resumed kernel. Load hibernate's temporary copy into el2.
 456          *
 457          * We can skip this step if we booted at EL1, or are running with VHE.
 458          */
 459         if (el2_reset_needed())
 460                 __hyp_set_vectors(el2_vectors);
 461
 462         hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
 463                        resume_hdr.reenter_kernel, restore_pblist,
 464                        resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));
 465
 466         return 0;
 467 }
 468
 469 int hibernate_resume_nonboot_cpu_disable(void)
 470 {
 471         if (sleep_cpu < 0) {
 472                 pr_err("Failing to resume from hibernate on an unknown CPU.\n");
 473                 return -ENODEV;
 474         }
 475
 476         return freeze_secondary_cpus(sleep_cpu);
 477 }