arch/arm64/kernel/machine_kexec.c

   1 /*
   2  * kexec for arm64
   3  *
   4  * Copyright (C) Linaro.
   5  * Copyright (C) Huawei Futurewei Technologies.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/kexec.h>
  13 #include <linux/smp.h>
  14
  15 #include <asm/cacheflush.h>
  16 #include <asm/cpu_ops.h>
  17 #include <asm/mmu.h>
  18 #include <asm/mmu_context.h>
  19 #include <asm/page.h>
  20
  21 #include "cpu-reset.h"
  22
  23 /* Global variables for the arm64_relocate_new_kernel routine. */
  24 extern const unsigned char arm64_relocate_new_kernel[];
  25 extern const unsigned long arm64_relocate_new_kernel_size;
  26
  27 /**
  28  * kexec_image_info - For debugging output.
  29  */
  30 #define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
  31 static void _kexec_image_info(const char *func, int line,
  32         const struct kimage *kimage)
  33 {
  34         unsigned long i;
  35
  36         pr_debug("%s:%d:\n", func, line);
  37         pr_debug("  kexec kimage info:\n");
  38         pr_debug("    type:        %d\n", kimage->type);
  39         pr_debug("    start:       %lx\n", kimage->start);
  40         pr_debug("    head:        %lx\n", kimage->head);
  41         pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
  42
  43         for (i = 0; i < kimage->nr_segments; i++) {
  44                 pr_debug("      segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
  45                         i,
  46                         kimage->segment[i].mem,
  47                         kimage->segment[i].mem + kimage->segment[i].memsz,
  48                         kimage->segment[i].memsz,
  49                         kimage->segment[i].memsz /  PAGE_SIZE);
  50         }
  51 }
  52
  53 void machine_kexec_cleanup(struct kimage *kimage)
  54 {
  55         /* Empty routine needed to avoid build errors. */
  56 }
  57
  58 /**
  59  * machine_kexec_prepare - Prepare for a kexec reboot.
  60  *
  61  * Called from the core kexec code when a kernel image is loaded.
  62  * Forbid loading a kexec kernel if we have no way of hotplugging cpus or cpus
  63  * are stuck in the kernel. This avoids a panic once we hit machine_kexec().
  64  */
  65 int machine_kexec_prepare(struct kimage *kimage)
  66 {
  67         kexec_image_info(kimage);
  68
  69         if (kimage->type != KEXEC_TYPE_CRASH && cpus_are_stuck_in_kernel()) {
  70                 pr_err("Can't kexec: CPUs are stuck in the kernel.\n");
  71                 return -EBUSY;
  72         }
  73
  74         return 0;
  75 }
  76
  77 /**
  78  * kexec_list_flush - Helper to flush the kimage list and source pages to PoC.
  79  */
  80 static void kexec_list_flush(struct kimage *kimage)
  81 {
  82         kimage_entry_t *entry;
  83
  84         for (entry = &kimage->head; ; entry++) {
  85                 unsigned int flag;
  86                 void *addr;
  87
  88                 /* flush the list entries. */
  89                 __flush_dcache_area(entry, sizeof(kimage_entry_t));
  90
  91                 flag = *entry & IND_FLAGS;
  92                 if (flag == IND_DONE)
  93                         break;
  94
  95                 addr = phys_to_virt(*entry & PAGE_MASK);
  96
  97                 switch (flag) {
  98                 case IND_INDIRECTION:
  99                         /* Set entry point just before the new list page. */
 100                         entry = (kimage_entry_t *)addr - 1;
 101                         break;
 102                 case IND_SOURCE:
 103                         /* flush the source pages. */
 104                         __flush_dcache_area(addr, PAGE_SIZE);
 105                         break;
 106                 case IND_DESTINATION:
 107                         break;
 108                 default:
 109                         BUG();
 110                 }
 111         }
 112 }
 113
 114 /**
 115  * kexec_segment_flush - Helper to flush the kimage segments to PoC.
 116  */
 117 static void kexec_segment_flush(const struct kimage *kimage)
 118 {
 119         unsigned long i;
 120
 121         pr_debug("%s:\n", __func__);
 122
 123         for (i = 0; i < kimage->nr_segments; i++) {
 124                 pr_debug("  segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
 125                         i,
 126                         kimage->segment[i].mem,
 127                         kimage->segment[i].mem + kimage->segment[i].memsz,
 128                         kimage->segment[i].memsz,
 129                         kimage->segment[i].memsz /  PAGE_SIZE);
 130
 131                 __flush_dcache_area(phys_to_virt(kimage->segment[i].mem),
 132                         kimage->segment[i].memsz);
 133         }
 134 }
 135
 136 /**
 137  * machine_kexec - Do the kexec reboot.
 138  *
 139  * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC.
 140  */
 141 void machine_kexec(struct kimage *kimage)
 142 {
 143         phys_addr_t reboot_code_buffer_phys;
 144         void *reboot_code_buffer;
 145
 146         /*
 147          * New cpus may have become stuck_in_kernel after we loaded the image.
 148          */
 149         BUG_ON(cpus_are_stuck_in_kernel() || (num_online_cpus() > 1));
 150
 151         reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
 152         reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
 153
 154         kexec_image_info(kimage);
 155
 156         pr_debug("%s:%d: control_code_page:        %p\n", __func__, __LINE__,
 157                 kimage->control_code_page);
 158         pr_debug("%s:%d: reboot_code_buffer_phys:  %pa\n", __func__, __LINE__,
 159                 &reboot_code_buffer_phys);
 160         pr_debug("%s:%d: reboot_code_buffer:       %p\n", __func__, __LINE__,
 161                 reboot_code_buffer);
 162         pr_debug("%s:%d: relocate_new_kernel:      %p\n", __func__, __LINE__,
 163                 arm64_relocate_new_kernel);
 164         pr_debug("%s:%d: relocate_new_kernel_size: 0x%lx(%lu) bytes\n",
 165                 __func__, __LINE__, arm64_relocate_new_kernel_size,
 166                 arm64_relocate_new_kernel_size);
 167
 168         /*
 169          * Copy arm64_relocate_new_kernel to the reboot_code_buffer for use
 170          * after the kernel is shut down.
 171          */
 172         memcpy(reboot_code_buffer, arm64_relocate_new_kernel,
 173                 arm64_relocate_new_kernel_size);
 174
 175         /* Flush the reboot_code_buffer in preparation for its execution. */
 176         __flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
 177         flush_icache_range((uintptr_t)reboot_code_buffer,
 178                 arm64_relocate_new_kernel_size);
 179
 180         /* Flush the kimage list and its buffers. */
 181         kexec_list_flush(kimage);
 182
 183         /* Flush the new image if already in place. */
 184         if ((kimage != kexec_crash_image) && (kimage->head & IND_DONE))
 185                 kexec_segment_flush(kimage);
 186
 187         pr_info("Bye!\n");
 188
 189         /* Disable all DAIF exceptions. */
 190         asm volatile ("msr daifset, #0xf" : : : "memory");
 191
 192         /*
 193          * cpu_soft_restart will shutdown the MMU, disable data caches, then
 194          * transfer control to the reboot_code_buffer which contains a copy of
 195          * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel
 196          * uses physical addressing to relocate the new image to its final
 197          * position and transfers control to the image entry point when the
 198          * relocation is complete.
 199          */
 200
 201         cpu_soft_restart(1, reboot_code_buffer_phys, kimage->head,
 202                 kimage->start, 0);
 203
 204         BUG(); /* Should never get here. */
 205 }
 206
 207 void machine_crash_shutdown(struct pt_regs *regs)
 208 {
 209         /* Empty routine needed to avoid build errors. */
 210 }
 211
 212 void arch_kexec_protect_crashkres(void)
 213 {
 214         int i;
 215
 216         kexec_segment_flush(kexec_crash_image);
 217
 218         for (i = 0; i < kexec_crash_image->nr_segments; i++)
 219                 set_memory_valid(
 220                         __phys_to_virt(kexec_crash_image->segment[i].mem),
 221                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 0);
 222 }
 223
 224 void arch_kexec_unprotect_crashkres(void)
 225 {
 226         int i;
 227
 228         for (i = 0; i < kexec_crash_image->nr_segments; i++)
 229                 set_memory_valid(
 230                         __phys_to_virt(kexec_crash_image->segment[i].mem),
 231                         kexec_crash_image->segment[i].memsz >> PAGE_SHIFT, 1);
 232 }