arch/arm/kernel/machine_kexec.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * machine_kexec.c - handle transition of Linux booting another kernel
   4  */
   5
   6 #include <linux/mm.h>
   7 #include <linux/kexec.h>
   8 #include <linux/delay.h>
   9 #include <linux/reboot.h>
  10 #include <linux/io.h>
  11 #include <linux/irq.h>
  12 #include <linux/memblock.h>
  13 #include <linux/of_fdt.h>
  14 #include <asm/mmu_context.h>
  15 #include <asm/cacheflush.h>
  16 #include <asm/kexec-internal.h>
  17 #include <asm/fncpy.h>
  18 #include <asm/mach-types.h>
  19 #include <asm/smp_plat.h>
  20 #include <asm/system_misc.h>
  21 #include <asm/set_memory.h>
  22
  23 extern void relocate_new_kernel(void);
  24 extern const unsigned int relocate_new_kernel_size;
  25
  26 static atomic_t waiting_for_crash_ipi;
  27
  28 /*
  29  * Provide a dummy crash_notes definition while crash dump arrives to arm.
  30  * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
  31  */
  32
  33 int machine_kexec_prepare(struct kimage *image)
  34 {
  35         struct kexec_segment *current_segment;
  36         __be32 header;
  37         int i, err;
  38
  39         image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET
  40                                      + KEXEC_ARM_ATAGS_OFFSET;
  41
  42         /*
  43          * Validate that if the current HW supports SMP, then the SW supports
  44          * and implements CPU hotplug for the current HW. If not, we won't be
  45          * able to kexec reliably, so fail the prepare operation.
  46          */
  47         if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&
  48             !platform_can_cpu_hotplug())
  49                 return -EINVAL;
  50
  51         /*
  52          * No segment at default ATAGs address. try to locate
  53          * a dtb using magic.
  54          */
  55         for (i = 0; i < image->nr_segments; i++) {
  56                 current_segment = &image->segment[i];
  57
  58                 if (!memblock_is_region_memory(idmap_to_phys(current_segment->mem),
  59                                                current_segment->memsz))
  60                         return -EINVAL;
  61
  62                 err = get_user(header, (__be32*)current_segment->buf);
  63                 if (err)
  64                         return err;
  65
  66                 if (header == cpu_to_be32(OF_DT_HEADER))
  67                         image->arch.kernel_r2 = current_segment->mem;
  68         }
  69         return 0;
  70 }
  71
  72 void machine_kexec_cleanup(struct kimage *image)
  73 {
  74 }
  75
  76 void machine_crash_nonpanic_core(void *unused)
  77 {
  78         struct pt_regs regs;
  79
  80         crash_setup_regs(&regs, get_irq_regs());
  81         printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
  82                smp_processor_id());
  83         crash_save_cpu(&regs, smp_processor_id());
  84         flush_cache_all();
  85
  86         set_cpu_online(smp_processor_id(), false);
  87         atomic_dec(&waiting_for_crash_ipi);
  88
  89         while (1) {
  90                 cpu_relax();
  91                 wfe();
  92         }
  93 }
  94
  95 static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
  96         CSD_INIT(machine_crash_nonpanic_core, NULL);
  97
  98 void crash_smp_send_stop(void)
  99 {
 100         static int cpus_stopped;
 101         unsigned long msecs;
 102         call_single_data_t *csd;
 103         int cpu, this_cpu = raw_smp_processor_id();
 104
 105         if (cpus_stopped)
 106                 return;
 107
 108         atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
 109         for_each_online_cpu(cpu) {
 110                 if (cpu == this_cpu)
 111                         continue;
 112
 113                 csd = &per_cpu(cpu_stop_csd, cpu);
 114                 smp_call_function_single_async(cpu, csd);
 115         }
 116
 117         msecs = 1000; /* Wait at most a second for the other cpus to stop */
 118         while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 119                 mdelay(1);
 120                 msecs--;
 121         }
 122         if (atomic_read(&waiting_for_crash_ipi) > 0)
 123                 pr_warn("Non-crashing CPUs did not react to IPI\n");
 124
 125         cpus_stopped = 1;
 126 }
 127
 128 static void machine_kexec_mask_interrupts(void)
 129 {
 130         unsigned int i;
 131         struct irq_desc *desc;
 132
 133         for_each_irq_desc(i, desc) {
 134                 struct irq_chip *chip;
 135
 136                 chip = irq_desc_get_chip(desc);
 137                 if (!chip)
 138                         continue;
 139
 140                 if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
 141                         chip->irq_eoi(&desc->irq_data);
 142
 143                 if (chip->irq_mask)
 144                         chip->irq_mask(&desc->irq_data);
 145
 146                 if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
 147                         chip->irq_disable(&desc->irq_data);
 148         }
 149 }
 150
 151 void machine_crash_shutdown(struct pt_regs *regs)
 152 {
 153         local_irq_disable();
 154         crash_smp_send_stop();
 155
 156         crash_save_cpu(regs, smp_processor_id());
 157         machine_kexec_mask_interrupts();
 158
 159         pr_info("Loading crashdump kernel...\n");
 160 }
 161
 162 void machine_kexec(struct kimage *image)
 163 {
 164         unsigned long page_list, reboot_entry_phys;
 165         struct kexec_relocate_data *data;
 166         void (*reboot_entry)(void);
 167         void *reboot_code_buffer;
 168
 169         /*
 170          * This can only happen if machine_shutdown() failed to disable some
 171          * CPU, and that can only happen if the checks in
 172          * machine_kexec_prepare() were not correct. If this fails, we can't
 173          * reliably kexec anyway, so BUG_ON is appropriate.
 174          */
 175         BUG_ON(num_online_cpus() > 1);
 176
 177         page_list = image->head & PAGE_MASK;
 178
 179         reboot_code_buffer = page_address(image->control_code_page);
 180
 181         /* copy our kernel relocation code to the control code page */
 182         reboot_entry = fncpy(reboot_code_buffer,
 183                              &relocate_new_kernel,
 184                              relocate_new_kernel_size);
 185
 186         data = reboot_code_buffer + relocate_new_kernel_size;
 187         data->kexec_start_address = image->start;
 188         data->kexec_indirection_page = page_list;
 189         data->kexec_mach_type = machine_arch_type;
 190         data->kexec_r2 = image->arch.kernel_r2;
 191
 192         /* get the identity mapping physical address for the reboot code */
 193         reboot_entry_phys = virt_to_idmap(reboot_entry);
 194
 195         pr_info("Bye!\n");
 196
 197         soft_restart(reboot_entry_phys);
 198 }
 199
 200 void arch_crash_save_vmcoreinfo(void)
 201 {
 202 #ifdef CONFIG_ARM_LPAE
 203         VMCOREINFO_CONFIG(ARM_LPAE);
 204 #endif
 205 }