arch/arm64/kernel/machine_kexec.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * kexec for arm64
   4  *
   5  * Copyright (C) Linaro.
   6  * Copyright (C) Huawei Futurewei Technologies.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/irq.h>
  11 #include <linux/kernel.h>
  12 #include <linux/kexec.h>
  13 #include <linux/page-flags.h>
  14 #include <linux/set_memory.h>
  15 #include <linux/smp.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/cpu_ops.h>
  19 #include <asm/daifflags.h>
  20 #include <asm/memory.h>
  21 #include <asm/mmu.h>
  22 #include <asm/mmu_context.h>
  23 #include <asm/page.h>
  24
  25 #include "cpu-reset.h"
  26
  27 /* Global variables for the arm64_relocate_new_kernel routine. */
  28 extern const unsigned char arm64_relocate_new_kernel[];
  29 extern const unsigned long arm64_relocate_new_kernel_size;
  30
  31 /**
  32  * kexec_image_info - For debugging output.
  33  */
  34 #define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
  35 static void _kexec_image_info(const char *func, int line,
  36         const struct kimage *kimage)
  37 {
  38         unsigned long i;
  39
  40         pr_debug("%s:%d:\n", func, line);
  41         pr_debug("  kexec kimage info:\n");
  42         pr_debug("    type:        %d\n", kimage->type);
  43         pr_debug("    start:       %lx\n", kimage->start);
  44         pr_debug("    head:        %lx\n", kimage->head);
  45         pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
  46         pr_debug("    kern_reloc: %pa\n", &kimage->arch.kern_reloc);
  47
  48         for (i = 0; i < kimage->nr_segments; i++) {
  49                 pr_debug("      segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
  50                         i,
  51                         kimage->segment[i].mem,
  52                         kimage->segment[i].mem + kimage->segment[i].memsz,
  53                         kimage->segment[i].memsz,
  54                         kimage->segment[i].memsz /  PAGE_SIZE);
  55         }
  56 }
  57
  58 void machine_kexec_cleanup(struct kimage *kimage)
  59 {
  60         /* Empty routine needed to avoid build errors. */
  61 }
  62
  63 int machine_kexec_post_load(struct kimage *kimage)
  64 {
  65         void *reloc_code = page_to_virt(kimage->control_code_page);
  66
  67         memcpy(reloc_code, arm64_relocate_new_kernel,
  68                arm64_relocate_new_kernel_size);
  69         kimage->arch.kern_reloc = __pa(reloc_code);
  70         kexec_image_info(kimage);
  71
  72         /*
  73          * For execution with the MMU off, reloc_code needs to be cleaned to the
  74          * PoC and invalidated from the I-cache.
  75          */
  76         dcache_clean_inval_poc((unsigned long)reloc_code,
  77                             (unsigned long)reloc_code +
  78                                     arm64_relocate_new_kernel_size);
  79         icache_inval_pou((uintptr_t)reloc_code,
  80                                 (uintptr_t)reloc_code +
  81                                         arm64_relocate_new_kernel_size);
  82
  83         return 0;
  84 }
  85
  86 /**
  87  * machine_kexec_prepare - Prepare for a kexec reboot.
  88  *
  89  * Called from the core kexec code when a kernel image is loaded.
  90  * Forbid loading a kexec kernel if we have no way of hotplugging cpus or cpus
  91  * are stuck in the kernel. This avoids a panic once we hit machine_kexec().
  92  */
  93 int machine_kexec_prepare(struct kimage *kimage)
  94 {
  95         if (kimage->type != KEXEC_TYPE_CRASH && cpus_are_stuck_in_kernel()) {
  96                 pr_err("Can't kexec: CPUs are stuck in the kernel.\n");
  97                 return -EBUSY;
  98         }
  99
 100         return 0;
 101 }
 102
 103 /**
 104  * kexec_list_flush - Helper to flush the kimage list and source pages to PoC.
 105  */
 106 static void kexec_list_flush(struct kimage *kimage)
 107 {
 108         kimage_entry_t *entry;
 109
 110         for (entry = &kimage->head; ; entry++) {
 111                 unsigned int flag;
 112                 unsigned long addr;
 113
 114                 /* flush the list entries. */
 115                 dcache_clean_inval_poc((unsigned long)entry,
 116                                     (unsigned long)entry +
 117                                             sizeof(kimage_entry_t));
 118
 119                 flag = *entry & IND_FLAGS;
 120                 if (flag == IND_DONE)
 121                         break;
 122
 123                 addr = (unsigned long)phys_to_virt(*entry & PAGE_MASK);
 124
 125                 switch (flag) {
 126                 case IND_INDIRECTION:
 127                         /* Set entry point just before the new list page. */
 128                         entry = (kimage_entry_t *)addr - 1;
 129                         break;
 130                 case IND_SOURCE:
 131                         /* flush the source pages. */
 132                         dcache_clean_inval_poc(addr, addr + PAGE_SIZE);
 133                         break;
 134                 case IND_DESTINATION:
 135                         break;
 136                 default:
 137                         BUG();
 138                 }
 139         }
 140 }
 141
 142 /**
 143  * kexec_segment_flush - Helper to flush the kimage segments to PoC.
 144  */
 145 static void kexec_segment_flush(const struct kimage *kimage)
 146 {
 147         unsigned long i;
 148
 149         pr_debug("%s:\n", __func__);
 150
 151         for (i = 0; i < kimage->nr_segments; i++) {
 152                 pr_debug("  segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
 153                         i,
 154                         kimage->segment[i].mem,
 155                         kimage->segment[i].mem + kimage->segment[i].memsz,
 156                         kimage->segment[i].memsz,
 157                         kimage->segment[i].memsz /  PAGE_SIZE);
 158
 159                 dcache_clean_inval_poc(
 160                         (unsigned long)phys_to_virt(kimage->segment[i].mem),
 161                         (unsigned long)phys_to_virt(kimage->segment[i].mem) +
 162                                 kimage->segment[i].memsz);
 163         }
 164 }
 165
 166 /**
 167  * machine_kexec - Do the kexec reboot.
 168  *
 169  * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC.
 170  */
 171 void machine_kexec(struct kimage *kimage)
 172 {
 173         bool in_kexec_crash = (kimage == kexec_crash_image);
 174         bool stuck_cpus = cpus_are_stuck_in_kernel();
 175
 176         /*
 177          * New cpus may have become stuck_in_kernel after we loaded the image.
 178          */
 179         BUG_ON(!in_kexec_crash && (stuck_cpus || (num_online_cpus() > 1)));
 180         WARN(in_kexec_crash && (stuck_cpus || smp_crash_stop_failed()),
 181                 "Some CPUs may be stale, kdump will be unreliable.\n");
 182
 183         /* Flush the kimage list and its buffers. */
 184         kexec_list_flush(kimage);
 185
 186         /* Flush the new image if already in place. */
 187         if ((kimage != kexec_crash_image) && (kimage->head & IND_DONE))
 188                 kexec_segment_flush(kimage);
 189
 190         pr_info("Bye!\n");
 191
 192         local_daif_mask();
 193
 194         /*
 195          * cpu_soft_restart will shutdown the MMU, disable data caches, then
 196          * transfer control to the kern_reloc which contains a copy of
 197          * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel
 198          * uses physical addressing to relocate the new image to its final
 199          * position and transfers control to the image entry point when the
 200          * relocation is complete.
 201          * In kexec case, kimage->start points to purgatory assuming that
 202          * kernel entry and dtb address are embedded in purgatory by
 203          * userspace (kexec-tools).
 204          * In kexec_file case, the kernel starts directly without purgatory.
 205          */
 206         cpu_soft_restart(kimage->arch.kern_reloc, kimage->head, kimage->start,
 207                          kimage->arch.dtb_mem);
 208
 209         BUG(); /* Should never get here. */
 210 }
 211
 212 static void machine_kexec_mask_interrupts(void)
 213 {
 214         unsigned int i;
 215         struct irq_desc *desc;
 216
 217         for_each_irq_desc(i, desc) {
 218                 struct irq_chip *chip;
 219                 int ret;
 220
 221                 chip = irq_desc_get_chip(desc);
 222                 if (!chip)
 223                         continue;
 224
 225                 /*
 226                  * First try to remove the active state. If this
 227                  * fails, try to EOI the interrupt.
 228                  */
 229                 ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);
 230
 231                 if (ret && irqd_irq_inprogress(&desc->irq_data) &&
 232                     chip->irq_eoi)
 233                         chip->irq_eoi(&desc->irq_data);
 234
 235                 if (chip->irq_mask)
 236                         chip->irq_mask(&desc->irq_data);
 237
 238                 if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
 239                         chip->irq_disable(&desc->irq_data);
 240         }
 241 }
 242
 243 /**
 244  * machine_crash_shutdown - shutdown non-crashing cpus and save registers
 245  */
 246 void machine_crash_shutdown(struct pt_regs *regs)
 247 {
 248         local_irq_disable();
 249
 250         /* shutdown non-crashing cpus */
 251         crash_smp_send_stop();
 252
 253         /* for crashing cpu */
 254         crash_save_cpu(regs, smp_processor_id());
 255         machine_kexec_mask_interrupts();
 256
 257         pr_info("Starting crashdump kernel...\n");
 258 }
 259
 260 void arch_kexec_protect_crashkres(void)
 261 {
 262         int i;
 263
 264         kexec_segment_flush(kexec_crash_image);
 265
 266         for (i = 0; i < kexec_crash_image->nr_segments; i++)
 267                 set_memory_valid(
 268                         __phys_to_virt(kexec_crash_image->segment[i].mem),
 269                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 0);
 270 }
 271
 272 void arch_kexec_unprotect_crashkres(void)
 273 {
 274         int i;
 275
 276         for (i = 0; i < kexec_crash_image->nr_segments; i++)
 277                 set_memory_valid(
 278                         __phys_to_virt(kexec_crash_image->segment[i].mem),
 279                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 1);
 280 }
 281
 282 #ifdef CONFIG_HIBERNATION
 283 /*
 284  * To preserve the crash dump kernel image, the relevant memory segments
 285  * should be mapped again around the hibernation.
 286  */
 287 void crash_prepare_suspend(void)
 288 {
 289         if (kexec_crash_image)
 290                 arch_kexec_unprotect_crashkres();
 291 }
 292
 293 void crash_post_resume(void)
 294 {
 295         if (kexec_crash_image)
 296                 arch_kexec_protect_crashkres();
 297 }
 298
 299 /*
 300  * crash_is_nosave
 301  *
 302  * Return true only if a page is part of reserved memory for crash dump kernel,
 303  * but does not hold any data of loaded kernel image.
 304  *
 305  * Note that all the pages in crash dump kernel memory have been initially
 306  * marked as Reserved as memory was allocated via memblock_reserve().
 307  *
 308  * In hibernation, the pages which are Reserved and yet "nosave" are excluded
 309  * from the hibernation iamge. crash_is_nosave() does thich check for crash
 310  * dump kernel and will reduce the total size of hibernation image.
 311  */
 312
 313 bool crash_is_nosave(unsigned long pfn)
 314 {
 315         int i;
 316         phys_addr_t addr;
 317
 318         if (!crashk_res.end)
 319                 return false;
 320
 321         /* in reserved memory? */
 322         addr = __pfn_to_phys(pfn);
 323         if ((addr < crashk_res.start) || (crashk_res.end < addr))
 324                 return false;
 325
 326         if (!kexec_crash_image)
 327                 return true;
 328
 329         /* not part of loaded kernel image? */
 330         for (i = 0; i < kexec_crash_image->nr_segments; i++)
 331                 if (addr >= kexec_crash_image->segment[i].mem &&
 332                                 addr < (kexec_crash_image->segment[i].mem +
 333                                         kexec_crash_image->segment[i].memsz))
 334                         return false;
 335
 336         return true;
 337 }
 338
 339 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 340 {
 341         unsigned long addr;
 342         struct page *page;
 343
 344         for (addr = begin; addr < end; addr += PAGE_SIZE) {
 345                 page = phys_to_page(addr);
 346                 free_reserved_page(page);
 347         }
 348 }
 349 #endif /* CONFIG_HIBERNATION */