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  *  https://lkml.org/lkml/2010/6/18/4
  11  *  https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html
  12  *  https://patchwork.kernel.org/patch/96442/
  13  *
  14  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  15  */
  16 #define pr_fmt(x) "hibernate: " x
  17 #include <linux/cpu.h>
  18 #include <linux/kvm_host.h>
  19 #include <linux/pm.h>
  20 #include <linux/sched.h>
  21 #include <linux/suspend.h>
  22 #include <linux/utsname.h>
  23
  24 #include <asm/barrier.h>
  25 #include <asm/cacheflush.h>
  26 #include <asm/cputype.h>
  27 #include <asm/daifflags.h>
  28 #include <asm/irqflags.h>
  29 #include <asm/kexec.h>
  30 #include <asm/memory.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/mte.h>
  33 #include <asm/sections.h>
  34 #include <asm/smp.h>
  35 #include <asm/smp_plat.h>
  36 #include <asm/suspend.h>
  37 #include <asm/sysreg.h>
  38 #include <asm/trans_pgd.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 /* Do we need to reset el2? */
  52 #define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())
  53
  54 /* temporary el2 vectors in the __hibernate_exit_text section. */
  55 extern char hibernate_el2_vectors[];
  56
  57 /* hyp-stub vectors, used to restore el2 during resume from hibernate. */
  58 extern char __hyp_stub_vectors[];
  59
  60 /*
  61  * The logical cpu number we should resume on, initialised to a non-cpu
  62  * number.
  63  */
  64 static int sleep_cpu = -EINVAL;
  65
  66 /*
  67  * Values that may not change over hibernate/resume. We put the build number
  68  * and date in here so that we guarantee not to resume with a different
  69  * kernel.
  70  */
  71 struct arch_hibernate_hdr_invariants {
  72         char            uts_version[__NEW_UTS_LEN + 1];
  73 };
  74
  75 /* These values need to be know across a hibernate/restore. */
  76 static struct arch_hibernate_hdr {
  77         struct arch_hibernate_hdr_invariants invariants;
  78
  79         /* These are needed to find the relocated kernel if built with kaslr */
  80         phys_addr_t     ttbr1_el1;
  81         void            (*reenter_kernel)(void);
  82
  83         /*
  84          * We need to know where the __hyp_stub_vectors are after restore to
  85          * re-configure el2.
  86          */
  87         phys_addr_t     __hyp_stub_vectors;
  88
  89         u64             sleep_cpu_mpidr;
  90 } resume_hdr;
  91
  92 static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
  93 {
  94         memset(i, 0, sizeof(*i));
  95         memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
  96 }
  97
  98 int pfn_is_nosave(unsigned long pfn)
  99 {
 100         unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
 101         unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
 102
 103         return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
 104                 crash_is_nosave(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          = __pa_symbol(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 = __pa_symbol(__hyp_stub_vectors);
 130         else
 131                 hdr->__hyp_stub_vectors = 0;
 132
 133         /* Save the mpidr of the cpu we called cpu_suspend() on... */
 134         if (sleep_cpu < 0) {
 135                 pr_err("Failing to hibernate on an unknown CPU.\n");
 136                 return -ENODEV;
 137         }
 138         hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
 139         pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
 140                 hdr->sleep_cpu_mpidr);
 141
 142         return 0;
 143 }
 144 EXPORT_SYMBOL(arch_hibernation_header_save);
 145
 146 int arch_hibernation_header_restore(void *addr)
 147 {
 148         int ret;
 149         struct arch_hibernate_hdr_invariants invariants;
 150         struct arch_hibernate_hdr *hdr = addr;
 151
 152         arch_hdr_invariants(&invariants);
 153         if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
 154                 pr_crit("Hibernate image not generated by this kernel!\n");
 155                 return -EINVAL;
 156         }
 157
 158         sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
 159         pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
 160                 hdr->sleep_cpu_mpidr);
 161         if (sleep_cpu < 0) {
 162                 pr_crit("Hibernated on a CPU not known to this kernel!\n");
 163                 sleep_cpu = -EINVAL;
 164                 return -EINVAL;
 165         }
 166
 167         ret = bringup_hibernate_cpu(sleep_cpu);
 168         if (ret) {
 169                 sleep_cpu = -EINVAL;
 170                 return ret;
 171         }
 172
 173         resume_hdr = *hdr;
 174
 175         return 0;
 176 }
 177 EXPORT_SYMBOL(arch_hibernation_header_restore);
 178
 179 static void *hibernate_page_alloc(void *arg)
 180 {
 181         return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
 182 }
 183
 184 /*
 185  * Copies length bytes, starting at src_start into an new page,
 186  * perform cache maintenance, then maps it at the specified address low
 187  * address as executable.
 188  *
 189  * This is used by hibernate to copy the code it needs to execute when
 190  * overwriting the kernel text. This function generates a new set of page
 191  * tables, which it loads into ttbr0.
 192  *
 193  * Length is provided as we probably only want 4K of data, even on a 64K
 194  * page system.
 195  */
 196 static int create_safe_exec_page(void *src_start, size_t length,
 197                                  phys_addr_t *phys_dst_addr)
 198 {
 199         struct trans_pgd_info trans_info = {
 200                 .trans_alloc_page       = hibernate_page_alloc,
 201                 .trans_alloc_arg        = (__force void *)GFP_ATOMIC,
 202         };
 203
 204         void *page = (void *)get_safe_page(GFP_ATOMIC);
 205         phys_addr_t trans_ttbr0;
 206         unsigned long t0sz;
 207         int rc;
 208
 209         if (!page)
 210                 return -ENOMEM;
 211
 212         memcpy(page, src_start, length);
 213         caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
 214         rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
 215         if (rc)
 216                 return rc;
 217
 218         /*
 219          * Load our new page tables. A strict BBM approach requires that we
 220          * ensure that TLBs are free of any entries that may overlap with the
 221          * global mappings we are about to install.
 222          *
 223          * For a real hibernate/resume cycle TTBR0 currently points to a zero
 224          * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI
 225          * runtime services), while for a userspace-driven test_resume cycle it
 226          * points to userspace page tables (and we must point it at a zero page
 227          * ourselves).
 228          *
 229          * We change T0SZ as part of installing the idmap. This is undone by
 230          * cpu_uninstall_idmap() in __cpu_suspend_exit().
 231          */
 232         cpu_set_reserved_ttbr0();
 233         local_flush_tlb_all();
 234         __cpu_set_tcr_t0sz(t0sz);
 235         write_sysreg(trans_ttbr0, ttbr0_el1);
 236         isb();
 237
 238         *phys_dst_addr = virt_to_phys(page);
 239
 240         return 0;
 241 }
 242
 243 #ifdef CONFIG_ARM64_MTE
 244
 245 static DEFINE_XARRAY(mte_pages);
 246
 247 static int save_tags(struct page *page, unsigned long pfn)
 248 {
 249         void *tag_storage, *ret;
 250
 251         tag_storage = mte_allocate_tag_storage();
 252         if (!tag_storage)
 253                 return -ENOMEM;
 254
 255         mte_save_page_tags(page_address(page), tag_storage);
 256
 257         ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
 258         if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
 259                 mte_free_tag_storage(tag_storage);
 260                 return xa_err(ret);
 261         } else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
 262                 mte_free_tag_storage(ret);
 263         }
 264
 265         return 0;
 266 }
 267
 268 static void swsusp_mte_free_storage(void)
 269 {
 270         XA_STATE(xa_state, &mte_pages, 0);
 271         void *tags;
 272
 273         xa_lock(&mte_pages);
 274         xas_for_each(&xa_state, tags, ULONG_MAX) {
 275                 mte_free_tag_storage(tags);
 276         }
 277         xa_unlock(&mte_pages);
 278
 279         xa_destroy(&mte_pages);
 280 }
 281
 282 static int swsusp_mte_save_tags(void)
 283 {
 284         struct zone *zone;
 285         unsigned long pfn, max_zone_pfn;
 286         int ret = 0;
 287         int n = 0;
 288
 289         if (!system_supports_mte())
 290                 return 0;
 291
 292         for_each_populated_zone(zone) {
 293                 max_zone_pfn = zone_end_pfn(zone);
 294                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
 295                         struct page *page = pfn_to_online_page(pfn);
 296
 297                         if (!page)
 298                                 continue;
 299
 300                         if (!test_bit(PG_mte_tagged, &page->flags))
 301                                 continue;
 302
 303                         ret = save_tags(page, pfn);
 304                         if (ret) {
 305                                 swsusp_mte_free_storage();
 306                                 goto out;
 307                         }
 308
 309                         n++;
 310                 }
 311         }
 312         pr_info("Saved %d MTE pages\n", n);
 313
 314 out:
 315         return ret;
 316 }
 317
 318 static void swsusp_mte_restore_tags(void)
 319 {
 320         XA_STATE(xa_state, &mte_pages, 0);
 321         int n = 0;
 322         void *tags;
 323
 324         xa_lock(&mte_pages);
 325         xas_for_each(&xa_state, tags, ULONG_MAX) {
 326                 unsigned long pfn = xa_state.xa_index;
 327                 struct page *page = pfn_to_online_page(pfn);
 328
 329                 /*
 330                  * It is not required to invoke page_kasan_tag_reset(page)
 331                  * at this point since the tags stored in page->flags are
 332                  * already restored.
 333                  */
 334                 mte_restore_page_tags(page_address(page), tags);
 335
 336                 mte_free_tag_storage(tags);
 337                 n++;
 338         }
 339         xa_unlock(&mte_pages);
 340
 341         pr_info("Restored %d MTE pages\n", n);
 342
 343         xa_destroy(&mte_pages);
 344 }
 345
 346 #else   /* CONFIG_ARM64_MTE */
 347
 348 static int swsusp_mte_save_tags(void)
 349 {
 350         return 0;
 351 }
 352
 353 static void swsusp_mte_restore_tags(void)
 354 {
 355 }
 356
 357 #endif  /* CONFIG_ARM64_MTE */
 358
 359 int swsusp_arch_suspend(void)
 360 {
 361         int ret = 0;
 362         unsigned long flags;
 363         struct sleep_stack_data state;
 364
 365         if (cpus_are_stuck_in_kernel()) {
 366                 pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
 367                 return -EBUSY;
 368         }
 369
 370         flags = local_daif_save();
 371
 372         if (__cpu_suspend_enter(&state)) {
 373                 /* make the crash dump kernel image visible/saveable */
 374                 crash_prepare_suspend();
 375
 376                 ret = swsusp_mte_save_tags();
 377                 if (ret)
 378                         return ret;
 379
 380                 sleep_cpu = smp_processor_id();
 381                 ret = swsusp_save();
 382         } else {
 383                 /* Clean kernel core startup/idle code to PoC*/
 384                 dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
 385                                     (unsigned long)__mmuoff_data_end);
 386                 dcache_clean_inval_poc((unsigned long)__idmap_text_start,
 387                                     (unsigned long)__idmap_text_end);
 388
 389                 /* Clean kvm setup code to PoC? */
 390                 if (el2_reset_needed()) {
 391                         dcache_clean_inval_poc(
 392                                 (unsigned long)__hyp_idmap_text_start,
 393                                 (unsigned long)__hyp_idmap_text_end);
 394                         dcache_clean_inval_poc((unsigned long)__hyp_text_start,
 395                                             (unsigned long)__hyp_text_end);
 396                 }
 397
 398                 swsusp_mte_restore_tags();
 399
 400                 /* make the crash dump kernel image protected again */
 401                 crash_post_resume();
 402
 403                 /*
 404                  * Tell the hibernation core that we've just restored
 405                  * the memory
 406                  */
 407                 in_suspend = 0;
 408
 409                 sleep_cpu = -EINVAL;
 410                 __cpu_suspend_exit();
 411
 412                 /*
 413                  * Just in case the boot kernel did turn the SSBD
 414                  * mitigation off behind our back, let's set the state
 415                  * to what we expect it to be.
 416                  */
 417                 spectre_v4_enable_mitigation(NULL);
 418         }
 419
 420         local_daif_restore(flags);
 421
 422         return ret;
 423 }
 424
 425 /*
 426  * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
 427  *
 428  * Memory allocated by get_safe_page() will be dealt with by the hibernate code,
 429  * we don't need to free it here.
 430  */
 431 int swsusp_arch_resume(void)
 432 {
 433         int rc;
 434         void *zero_page;
 435         size_t exit_size;
 436         pgd_t *tmp_pg_dir;
 437         void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
 438                                           void *, phys_addr_t, phys_addr_t);
 439         struct trans_pgd_info trans_info = {
 440                 .trans_alloc_page       = hibernate_page_alloc,
 441                 .trans_alloc_arg        = (void *)GFP_ATOMIC,
 442         };
 443
 444         /*
 445          * Restoring the memory image will overwrite the ttbr1 page tables.
 446          * Create a second copy of just the linear map, and use this when
 447          * restoring.
 448          */
 449         rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
 450                                    PAGE_END);
 451         if (rc)
 452                 return rc;
 453
 454         /*
 455          * We need a zero page that is zero before & after resume in order to
 456          * to break before make on the ttbr1 page tables.
 457          */
 458         zero_page = (void *)get_safe_page(GFP_ATOMIC);
 459         if (!zero_page) {
 460                 pr_err("Failed to allocate zero page.\n");
 461                 return -ENOMEM;
 462         }
 463
 464         exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
 465         /*
 466          * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
 467          * a new set of ttbr0 page tables and load them.
 468          */
 469         rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
 470                                    (phys_addr_t *)&hibernate_exit);
 471         if (rc) {
 472                 pr_err("Failed to create safe executable page for hibernate_exit code.\n");
 473                 return rc;
 474         }
 475
 476         /*
 477          * The hibernate exit text contains a set of el2 vectors, that will
 478          * be executed at el2 with the mmu off in order to reload hyp-stub.
 479          */
 480         dcache_clean_inval_poc((unsigned long)hibernate_exit,
 481                             (unsigned long)hibernate_exit + exit_size);
 482
 483         /*
 484          * KASLR will cause the el2 vectors to be in a different location in
 485          * the resumed kernel. Load hibernate's temporary copy into el2.
 486          *
 487          * We can skip this step if we booted at EL1, or are running with VHE.
 488          */
 489         if (el2_reset_needed()) {
 490                 phys_addr_t el2_vectors = (phys_addr_t)hibernate_exit;
 491                 el2_vectors += hibernate_el2_vectors -
 492                                __hibernate_exit_text_start;     /* offset */
 493
 494                 __hyp_set_vectors(el2_vectors);
 495         }
 496
 497         hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
 498                        resume_hdr.reenter_kernel, restore_pblist,
 499                        resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));
 500
 501         return 0;
 502 }
 503
 504 int hibernate_resume_nonboot_cpu_disable(void)
 505 {
 506         if (sleep_cpu < 0) {
 507                 pr_err("Failing to resume from hibernate on an unknown CPU.\n");
 508                 return -ENODEV;
 509         }
 510
 511         return freeze_secondary_cpus(sleep_cpu);
 512 }