arch/x86/kernel/crash.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
   4  *
   5  * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   6  *
   7  * Copyright (C) IBM Corporation, 2004. All rights reserved.
   8  * Copyright (C) Red Hat Inc., 2014. All rights reserved.
   9  * Authors:
  10  *      Vivek Goyal <vgoyal@redhat.com>
  11  *
  12  */
  13
  14 #define pr_fmt(fmt)     "kexec: " fmt
  15
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/smp.h>
  19 #include <linux/reboot.h>
  20 #include <linux/kexec.h>
  21 #include <linux/delay.h>
  22 #include <linux/elf.h>
  23 #include <linux/elfcore.h>
  24 #include <linux/export.h>
  25 #include <linux/slab.h>
  26 #include <linux/vmalloc.h>
  27 #include <linux/memblock.h>
  28
  29 #include <asm/bootparam.h>
  30 #include <asm/processor.h>
  31 #include <asm/hardirq.h>
  32 #include <asm/nmi.h>
  33 #include <asm/hw_irq.h>
  34 #include <asm/apic.h>
  35 #include <asm/e820/types.h>
  36 #include <asm/io_apic.h>
  37 #include <asm/hpet.h>
  38 #include <linux/kdebug.h>
  39 #include <asm/cpu.h>
  40 #include <asm/reboot.h>
  41 #include <asm/intel_pt.h>
  42 #include <asm/crash.h>
  43 #include <asm/cmdline.h>
  44 #include <asm/sev.h>
  45
  46 /* Used while preparing memory map entries for second kernel */
  47 struct crash_memmap_data {
  48         struct boot_params *params;
  49         /* Type of memory */
  50         unsigned int type;
  51 };
  52
  53 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
  54
  55 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
  56 {
  57         crash_save_cpu(regs, cpu);
  58
  59         /*
  60          * Disable Intel PT to stop its logging
  61          */
  62         cpu_emergency_stop_pt();
  63
  64         kdump_sev_callback();
  65
  66         disable_local_APIC();
  67 }
  68
  69 void kdump_nmi_shootdown_cpus(void)
  70 {
  71         nmi_shootdown_cpus(kdump_nmi_callback);
  72
  73         disable_local_APIC();
  74 }
  75
  76 /* Override the weak function in kernel/panic.c */
  77 void crash_smp_send_stop(void)
  78 {
  79         static int cpus_stopped;
  80
  81         if (cpus_stopped)
  82                 return;
  83
  84         if (smp_ops.crash_stop_other_cpus)
  85                 smp_ops.crash_stop_other_cpus();
  86         else
  87                 smp_send_stop();
  88
  89         cpus_stopped = 1;
  90 }
  91
  92 #else
  93 void crash_smp_send_stop(void)
  94 {
  95         /* There are no cpus to shootdown */
  96 }
  97 #endif
  98
  99 void native_machine_crash_shutdown(struct pt_regs *regs)
 100 {
 101         /* This function is only called after the system
 102          * has panicked or is otherwise in a critical state.
 103          * The minimum amount of code to allow a kexec'd kernel
 104          * to run successfully needs to happen here.
 105          *
 106          * In practice this means shooting down the other cpus in
 107          * an SMP system.
 108          */
 109         /* The kernel is broken so disable interrupts */
 110         local_irq_disable();
 111
 112         crash_smp_send_stop();
 113
 114         cpu_emergency_disable_virtualization();
 115
 116         /*
 117          * Disable Intel PT to stop its logging
 118          */
 119         cpu_emergency_stop_pt();
 120
 121 #ifdef CONFIG_X86_IO_APIC
 122         /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 123         ioapic_zap_locks();
 124         clear_IO_APIC();
 125 #endif
 126         lapic_shutdown();
 127         restore_boot_irq_mode();
 128 #ifdef CONFIG_HPET_TIMER
 129         hpet_disable();
 130 #endif
 131
 132         /*
 133          * Non-crash kexec calls enc_kexec_begin() while scheduling is still
 134          * active. This allows the callback to wait until all in-flight
 135          * shared<->private conversions are complete. In a crash scenario,
 136          * enc_kexec_begin() gets called after all but one CPU have been shut
 137          * down and interrupts have been disabled. This allows the callback to
 138          * detect a race with the conversion and report it.
 139          */
 140         x86_platform.guest.enc_kexec_begin();
 141         x86_platform.guest.enc_kexec_finish();
 142
 143         crash_save_cpu(regs, safe_smp_processor_id());
 144 }
 145
 146 #if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
 147 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 148 {
 149         unsigned int *nr_ranges = arg;
 150
 151         (*nr_ranges)++;
 152         return 0;
 153 }
 154
 155 /* Gather all the required information to prepare elf headers for ram regions */
 156 static struct crash_mem *fill_up_crash_elf_data(void)
 157 {
 158         unsigned int nr_ranges = 0;
 159         struct crash_mem *cmem;
 160
 161         walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
 162         if (!nr_ranges)
 163                 return NULL;
 164
 165         /*
 166          * Exclusion of crash region and/or crashk_low_res may cause
 167          * another range split. So add extra two slots here.
 168          */
 169         nr_ranges += 2;
 170         cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
 171         if (!cmem)
 172                 return NULL;
 173
 174         cmem->max_nr_ranges = nr_ranges;
 175         cmem->nr_ranges = 0;
 176
 177         return cmem;
 178 }
 179
 180 /*
 181  * Look for any unwanted ranges between mstart, mend and remove them. This
 182  * might lead to split and split ranges are put in cmem->ranges[] array
 183  */
 184 static int elf_header_exclude_ranges(struct crash_mem *cmem)
 185 {
 186         int ret = 0;
 187
 188         /* Exclude the low 1M because it is always reserved */
 189         ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
 190         if (ret)
 191                 return ret;
 192
 193         /* Exclude crashkernel region */
 194         ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
 195         if (ret)
 196                 return ret;
 197
 198         if (crashk_low_res.end)
 199                 ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
 200                                               crashk_low_res.end);
 201
 202         return ret;
 203 }
 204
 205 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 206 {
 207         struct crash_mem *cmem = arg;
 208
 209         cmem->ranges[cmem->nr_ranges].start = res->start;
 210         cmem->ranges[cmem->nr_ranges].end = res->end;
 211         cmem->nr_ranges++;
 212
 213         return 0;
 214 }
 215
 216 /* Prepare elf headers. Return addr and size */
 217 static int prepare_elf_headers(void **addr, unsigned long *sz,
 218                                unsigned long *nr_mem_ranges)
 219 {
 220         struct crash_mem *cmem;
 221         int ret;
 222
 223         cmem = fill_up_crash_elf_data();
 224         if (!cmem)
 225                 return -ENOMEM;
 226
 227         ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 228         if (ret)
 229                 goto out;
 230
 231         /* Exclude unwanted mem ranges */
 232         ret = elf_header_exclude_ranges(cmem);
 233         if (ret)
 234                 goto out;
 235
 236         /* Return the computed number of memory ranges, for hotplug usage */
 237         *nr_mem_ranges = cmem->nr_ranges;
 238
 239         /* By default prepare 64bit headers */
 240         ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
 241
 242 out:
 243         vfree(cmem);
 244         return ret;
 245 }
 246 #endif
 247
 248 #ifdef CONFIG_KEXEC_FILE
 249 static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
 250 {
 251         unsigned int nr_e820_entries;
 252
 253         nr_e820_entries = params->e820_entries;
 254         if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
 255                 return 1;
 256
 257         memcpy(&params->e820_table[nr_e820_entries], entry, sizeof(struct e820_entry));
 258         params->e820_entries++;
 259         return 0;
 260 }
 261
 262 static int memmap_entry_callback(struct resource *res, void *arg)
 263 {
 264         struct crash_memmap_data *cmd = arg;
 265         struct boot_params *params = cmd->params;
 266         struct e820_entry ei;
 267
 268         ei.addr = res->start;
 269         ei.size = resource_size(res);
 270         ei.type = cmd->type;
 271         add_e820_entry(params, &ei);
 272
 273         return 0;
 274 }
 275
 276 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
 277                                  unsigned long long mstart,
 278                                  unsigned long long mend)
 279 {
 280         unsigned long start, end;
 281
 282         cmem->ranges[0].start = mstart;
 283         cmem->ranges[0].end = mend;
 284         cmem->nr_ranges = 1;
 285
 286         /* Exclude elf header region */
 287         start = image->elf_load_addr;
 288         end = start + image->elf_headers_sz - 1;
 289         return crash_exclude_mem_range(cmem, start, end);
 290 }
 291
 292 /* Prepare memory map for crash dump kernel */
 293 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 294 {
 295         int i, ret = 0;
 296         unsigned long flags;
 297         struct e820_entry ei;
 298         struct crash_memmap_data cmd;
 299         struct crash_mem *cmem;
 300
 301         cmem = vzalloc(struct_size(cmem, ranges, 1));
 302         if (!cmem)
 303                 return -ENOMEM;
 304
 305         memset(&cmd, 0, sizeof(struct crash_memmap_data));
 306         cmd.params = params;
 307
 308         /* Add the low 1M */
 309         cmd.type = E820_TYPE_RAM;
 310         flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 311         walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,
 312                             memmap_entry_callback);
 313
 314         /* Add ACPI tables */
 315         cmd.type = E820_TYPE_ACPI;
 316         flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 317         walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
 318                             memmap_entry_callback);
 319
 320         /* Add ACPI Non-volatile Storage */
 321         cmd.type = E820_TYPE_NVS;
 322         walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
 323                             memmap_entry_callback);
 324
 325         /* Add e820 reserved ranges */
 326         cmd.type = E820_TYPE_RESERVED;
 327         flags = IORESOURCE_MEM;
 328         walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd,
 329                             memmap_entry_callback);
 330
 331         /* Add crashk_low_res region */
 332         if (crashk_low_res.end) {
 333                 ei.addr = crashk_low_res.start;
 334                 ei.size = resource_size(&crashk_low_res);
 335                 ei.type = E820_TYPE_RAM;
 336                 add_e820_entry(params, &ei);
 337         }
 338
 339         /* Exclude some ranges from crashk_res and add rest to memmap */
 340         ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
 341         if (ret)
 342                 goto out;
 343
 344         for (i = 0; i < cmem->nr_ranges; i++) {
 345                 ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
 346
 347                 /* If entry is less than a page, skip it */
 348                 if (ei.size < PAGE_SIZE)
 349                         continue;
 350                 ei.addr = cmem->ranges[i].start;
 351                 ei.type = E820_TYPE_RAM;
 352                 add_e820_entry(params, &ei);
 353         }
 354
 355 out:
 356         vfree(cmem);
 357         return ret;
 358 }
 359
 360 int crash_load_segments(struct kimage *image)
 361 {
 362         int ret;
 363         unsigned long pnum = 0;
 364         struct kexec_buf kbuf = { .image = image, .buf_min = 0,
 365                                   .buf_max = ULONG_MAX, .top_down = false };
 366
 367         /* Prepare elf headers and add a segment */
 368         ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
 369         if (ret)
 370                 return ret;
 371
 372         image->elf_headers      = kbuf.buffer;
 373         image->elf_headers_sz   = kbuf.bufsz;
 374         kbuf.memsz              = kbuf.bufsz;
 375
 376 #ifdef CONFIG_CRASH_HOTPLUG
 377         /*
 378          * The elfcorehdr segment size accounts for VMCOREINFO, kernel_map,
 379          * maximum CPUs and maximum memory ranges.
 380          */
 381         if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
 382                 pnum = 2 + CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES;
 383         else
 384                 pnum += 2 + CONFIG_NR_CPUS_DEFAULT;
 385
 386         if (pnum < (unsigned long)PN_XNUM) {
 387                 kbuf.memsz = pnum * sizeof(Elf64_Phdr);
 388                 kbuf.memsz += sizeof(Elf64_Ehdr);
 389
 390                 image->elfcorehdr_index = image->nr_segments;
 391
 392                 /* Mark as usable to crash kernel, else crash kernel fails on boot */
 393                 image->elf_headers_sz = kbuf.memsz;
 394         } else {
 395                 pr_err("number of Phdrs %lu exceeds max\n", pnum);
 396         }
 397 #endif
 398
 399         kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
 400         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 401         ret = kexec_add_buffer(&kbuf);
 402         if (ret)
 403                 return ret;
 404         image->elf_load_addr = kbuf.mem;
 405         kexec_dprintk("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 406                       image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
 407
 408         return ret;
 409 }
 410 #endif /* CONFIG_KEXEC_FILE */
 411
 412 #ifdef CONFIG_CRASH_HOTPLUG
 413
 414 #undef pr_fmt
 415 #define pr_fmt(fmt) "crash hp: " fmt
 416
 417 int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
 418 {
 419
 420 #ifdef CONFIG_KEXEC_FILE
 421         if (image->file_mode)
 422                 return 1;
 423 #endif
 424         /*
 425          * Initially, crash hotplug support for kexec_load was added
 426          * with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this
 427          * functionality was expanded to accommodate multiple kexec
 428          * segment updates, leading to the introduction of the
 429          * KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag bit. Consequently,
 430          * when the kexec tool sends either of these flags, it indicates
 431          * that the required kexec segment (elfcorehdr) is excluded from
 432          * the SHA calculation.
 433          */
 434         return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR ||
 435                 kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT);
 436 }
 437
 438 unsigned int arch_crash_get_elfcorehdr_size(void)
 439 {
 440         unsigned int sz;
 441
 442         /* kernel_map, VMCOREINFO and maximum CPUs */
 443         sz = 2 + CONFIG_NR_CPUS_DEFAULT;
 444         if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
 445                 sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
 446         sz *= sizeof(Elf64_Phdr);
 447         return sz;
 448 }
 449
 450 /**
 451  * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes
 452  * @image: a pointer to kexec_crash_image
 453  * @arg: struct memory_notify handler for memory hotplug case and
 454  *       NULL for CPU hotplug case.
 455  *
 456  * Prepare the new elfcorehdr and replace the existing elfcorehdr.
 457  */
 458 void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
 459 {
 460         void *elfbuf = NULL, *old_elfcorehdr;
 461         unsigned long nr_mem_ranges;
 462         unsigned long mem, memsz;
 463         unsigned long elfsz = 0;
 464
 465         /*
 466          * As crash_prepare_elf64_headers() has already described all
 467          * possible CPUs, there is no need to update the elfcorehdr
 468          * for additional CPU changes.
 469          */
 470         if ((image->file_mode || image->elfcorehdr_updated) &&
 471                 ((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) ||
 472                 (image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU)))
 473                 return;
 474
 475         /*
 476          * Create the new elfcorehdr reflecting the changes to CPU and/or
 477          * memory resources.
 478          */
 479         if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
 480                 pr_err("unable to create new elfcorehdr");
 481                 goto out;
 482         }
 483
 484         /*
 485          * Obtain address and size of the elfcorehdr segment, and
 486          * check it against the new elfcorehdr buffer.
 487          */
 488         mem = image->segment[image->elfcorehdr_index].mem;
 489         memsz = image->segment[image->elfcorehdr_index].memsz;
 490         if (elfsz > memsz) {
 491                 pr_err("update elfcorehdr elfsz %lu > memsz %lu",
 492                         elfsz, memsz);
 493                 goto out;
 494         }
 495
 496         /*
 497          * Copy new elfcorehdr over the old elfcorehdr at destination.
 498          */
 499         old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
 500         if (!old_elfcorehdr) {
 501                 pr_err("mapping elfcorehdr segment failed\n");
 502                 goto out;
 503         }
 504
 505         /*
 506          * Temporarily invalidate the crash image while the
 507          * elfcorehdr is updated.
 508          */
 509         xchg(&kexec_crash_image, NULL);
 510         memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz);
 511         xchg(&kexec_crash_image, image);
 512         kunmap_local(old_elfcorehdr);
 513         pr_debug("updated elfcorehdr\n");
 514
 515 out:
 516         vfree(elfbuf);
 517 }
 518 #endif