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_context.h>
  18
  19 #include "cpu-reset.h"
  20
  21 /* Global variables for the arm64_relocate_new_kernel routine. */
  22 extern const unsigned char arm64_relocate_new_kernel[];
  23 extern const unsigned long arm64_relocate_new_kernel_size;
  24
  25 static unsigned long kimage_start;
  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         kimage_start = kimage->start;
  68
  69         kexec_image_info(kimage);
  70
  71         if (kimage->type != KEXEC_TYPE_CRASH && cpus_are_stuck_in_kernel()) {
  72                 pr_err("Can't kexec: CPUs are stuck in the kernel.\n");
  73                 return -EBUSY;
  74         }
  75
  76         return 0;
  77 }
  78
  79 /**
  80  * kexec_list_flush - Helper to flush the kimage list and source pages to PoC.
  81  */
  82 static void kexec_list_flush(struct kimage *kimage)
  83 {
  84         kimage_entry_t *entry;
  85
  86         for (entry = &kimage->head; ; entry++) {
  87                 unsigned int flag;
  88                 void *addr;
  89
  90                 /* flush the list entries. */
  91                 __flush_dcache_area(entry, sizeof(kimage_entry_t));
  92
  93                 flag = *entry & IND_FLAGS;
  94                 if (flag == IND_DONE)
  95                         break;
  96
  97                 addr = phys_to_virt(*entry & PAGE_MASK);
  98
  99                 switch (flag) {
 100                 case IND_INDIRECTION:
 101                         /* Set entry point just before the new list page. */
 102                         entry = (kimage_entry_t *)addr - 1;
 103                         break;
 104                 case IND_SOURCE:
 105                         /* flush the source pages. */
 106                         __flush_dcache_area(addr, PAGE_SIZE);
 107                         break;
 108                 case IND_DESTINATION:
 109                         break;
 110                 default:
 111                         BUG();
 112                 }
 113         }
 114 }
 115
 116 /**
 117  * kexec_segment_flush - Helper to flush the kimage segments to PoC.
 118  */
 119 static void kexec_segment_flush(const struct kimage *kimage)
 120 {
 121         unsigned long i;
 122
 123         pr_debug("%s:\n", __func__);
 124
 125         for (i = 0; i < kimage->nr_segments; i++) {
 126                 pr_debug("  segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
 127                         i,
 128                         kimage->segment[i].mem,
 129                         kimage->segment[i].mem + kimage->segment[i].memsz,
 130                         kimage->segment[i].memsz,
 131                         kimage->segment[i].memsz /  PAGE_SIZE);
 132
 133                 __flush_dcache_area(phys_to_virt(kimage->segment[i].mem),
 134                         kimage->segment[i].memsz);
 135         }
 136 }
 137
 138 /**
 139  * machine_kexec - Do the kexec reboot.
 140  *
 141  * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC.
 142  */
 143 void machine_kexec(struct kimage *kimage)
 144 {
 145         phys_addr_t reboot_code_buffer_phys;
 146         void *reboot_code_buffer;
 147
 148         /*
 149          * New cpus may have become stuck_in_kernel after we loaded the image.
 150          */
 151         BUG_ON(cpus_are_stuck_in_kernel() || (num_online_cpus() > 1));
 152
 153         reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
 154         reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
 155
 156         kexec_image_info(kimage);
 157
 158         pr_debug("%s:%d: control_code_page:        %p\n", __func__, __LINE__,
 159                 kimage->control_code_page);
 160         pr_debug("%s:%d: reboot_code_buffer_phys:  %pa\n", __func__, __LINE__,
 161                 &reboot_code_buffer_phys);
 162         pr_debug("%s:%d: reboot_code_buffer:       %p\n", __func__, __LINE__,
 163                 reboot_code_buffer);
 164         pr_debug("%s:%d: relocate_new_kernel:      %p\n", __func__, __LINE__,
 165                 arm64_relocate_new_kernel);
 166         pr_debug("%s:%d: relocate_new_kernel_size: 0x%lx(%lu) bytes\n",
 167                 __func__, __LINE__, arm64_relocate_new_kernel_size,
 168                 arm64_relocate_new_kernel_size);
 169
 170         /*
 171          * Copy arm64_relocate_new_kernel to the reboot_code_buffer for use
 172          * after the kernel is shut down.
 173          */
 174         memcpy(reboot_code_buffer, arm64_relocate_new_kernel,
 175                 arm64_relocate_new_kernel_size);
 176
 177         /* Flush the reboot_code_buffer in preparation for its execution. */
 178         __flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
 179         flush_icache_range((uintptr_t)reboot_code_buffer,
 180                 arm64_relocate_new_kernel_size);
 181
 182         /* Flush the kimage list and its buffers. */
 183         kexec_list_flush(kimage);
 184
 185         /* Flush the new image if already in place. */
 186         if (kimage->head & IND_DONE)
 187                 kexec_segment_flush(kimage);
 188
 189         pr_info("Bye!\n");
 190
 191         /* Disable all DAIF exceptions. */
 192         asm volatile ("msr daifset, #0xf" : : : "memory");
 193
 194         /*
 195          * cpu_soft_restart will shutdown the MMU, disable data caches, then
 196          * transfer control to the reboot_code_buffer 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          */
 202
 203         cpu_soft_restart(1, reboot_code_buffer_phys, kimage->head,
 204                 kimage_start, 0);
 205
 206         BUG(); /* Should never get here. */
 207 }
 208
 209 void machine_crash_shutdown(struct pt_regs *regs)
 210 {
 211         /* Empty routine needed to avoid build errors. */
 212 }