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 static void machine_crash_nonpanic_core(void *unused)
  77 {
  78         struct pt_regs regs;
  79
  80         local_fiq_disable();
  81
  82         crash_setup_regs(&regs, get_irq_regs());
  83         printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
  84                smp_processor_id());
  85         crash_save_cpu(&regs, smp_processor_id());
  86         flush_cache_all();
  87
  88         set_cpu_online(smp_processor_id(), false);
  89         atomic_dec(&waiting_for_crash_ipi);
  90
  91         while (1) {
  92                 cpu_relax();
  93                 wfe();
  94         }
  95 }
  96
  97 static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
  98         CSD_INIT(machine_crash_nonpanic_core, NULL);
  99
 100 void crash_smp_send_stop(void)
 101 {
 102         static int cpus_stopped;
 103         unsigned long msecs;
 104         call_single_data_t *csd;
 105         int cpu, this_cpu = raw_smp_processor_id();
 106
 107         if (cpus_stopped)
 108                 return;
 109
 110         atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
 111         for_each_online_cpu(cpu) {
 112                 if (cpu == this_cpu)
 113                         continue;
 114
 115                 csd = &per_cpu(cpu_stop_csd, cpu);
 116                 smp_call_function_single_async(cpu, csd);
 117         }
 118
 119         msecs = 1000; /* Wait at most a second for the other cpus to stop */
 120         while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 121                 mdelay(1);
 122                 msecs--;
 123         }
 124         if (atomic_read(&waiting_for_crash_ipi) > 0)
 125                 pr_warn("Non-crashing CPUs did not react to IPI\n");
 126
 127         cpus_stopped = 1;
 128 }
 129
 130 void machine_crash_shutdown(struct pt_regs *regs)
 131 {
 132         local_irq_disable();
 133         crash_smp_send_stop();
 134
 135         crash_save_cpu(regs, smp_processor_id());
 136         machine_kexec_mask_interrupts();
 137
 138         pr_info("Loading crashdump kernel...\n");
 139 }
 140
 141 void machine_kexec(struct kimage *image)
 142 {
 143         unsigned long page_list, reboot_entry_phys;
 144         struct kexec_relocate_data *data;
 145         void (*reboot_entry)(void);
 146         void *reboot_code_buffer;
 147
 148         /*
 149          * This can only happen if machine_shutdown() failed to disable some
 150          * CPU, and that can only happen if the checks in
 151          * machine_kexec_prepare() were not correct. If this fails, we can't
 152          * reliably kexec anyway, so BUG_ON is appropriate.
 153          */
 154         BUG_ON(num_online_cpus() > 1);
 155
 156         page_list = image->head & PAGE_MASK;
 157
 158         reboot_code_buffer = page_address(image->control_code_page);
 159
 160         /* copy our kernel relocation code to the control code page */
 161         reboot_entry = fncpy(reboot_code_buffer,
 162                              &relocate_new_kernel,
 163                              relocate_new_kernel_size);
 164
 165         data = reboot_code_buffer + relocate_new_kernel_size;
 166         data->kexec_start_address = image->start;
 167         data->kexec_indirection_page = page_list;
 168         data->kexec_mach_type = machine_arch_type;
 169         data->kexec_r2 = image->arch.kernel_r2;
 170
 171         /* get the identity mapping physical address for the reboot code */
 172         reboot_entry_phys = virt_to_idmap(reboot_entry);
 173
 174         pr_info("Bye!\n");
 175
 176         soft_restart(reboot_entry_phys);
 177 }