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 <asm/pgtable.h>
  14 #include <linux/of_fdt.h>
  15 #include <asm/pgalloc.h>
  16 #include <asm/mmu_context.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/fncpy.h>
  19 #include <asm/mach-types.h>
  20 #include <asm/smp_plat.h>
  21 #include <asm/system_misc.h>
  22 #include <asm/set_memory.h>
  23
  24 extern void relocate_new_kernel(void);
  25 extern const unsigned int relocate_new_kernel_size;
  26
  27 extern unsigned long kexec_start_address;
  28 extern unsigned long kexec_indirection_page;
  29 extern unsigned long kexec_mach_type;
  30 extern unsigned long kexec_boot_atags;
  31
  32 static atomic_t waiting_for_crash_ipi;
  33
  34 /*
  35  * Provide a dummy crash_notes definition while crash dump arrives to arm.
  36  * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
  37  */
  38
  39 int machine_kexec_prepare(struct kimage *image)
  40 {
  41         struct kexec_segment *current_segment;
  42         __be32 header;
  43         int i, err;
  44
  45         image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET
  46                                      + KEXEC_ARM_ATAGS_OFFSET;
  47
  48         /*
  49          * Validate that if the current HW supports SMP, then the SW supports
  50          * and implements CPU hotplug for the current HW. If not, we won't be
  51          * able to kexec reliably, so fail the prepare operation.
  52          */
  53         if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&
  54             !platform_can_cpu_hotplug())
  55                 return -EINVAL;
  56
  57         /*
  58          * No segment at default ATAGs address. try to locate
  59          * a dtb using magic.
  60          */
  61         for (i = 0; i < image->nr_segments; i++) {
  62                 current_segment = &image->segment[i];
  63
  64                 if (!memblock_is_region_memory(idmap_to_phys(current_segment->mem),
  65                                                current_segment->memsz))
  66                         return -EINVAL;
  67
  68                 err = get_user(header, (__be32*)current_segment->buf);
  69                 if (err)
  70                         return err;
  71
  72                 if (header == cpu_to_be32(OF_DT_HEADER))
  73                         image->arch.kernel_r2 = current_segment->mem;
  74         }
  75         return 0;
  76 }
  77
  78 void machine_kexec_cleanup(struct kimage *image)
  79 {
  80 }
  81
  82 void machine_crash_nonpanic_core(void *unused)
  83 {
  84         struct pt_regs regs;
  85
  86         crash_setup_regs(&regs, get_irq_regs());
  87         printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
  88                smp_processor_id());
  89         crash_save_cpu(&regs, smp_processor_id());
  90         flush_cache_all();
  91
  92         set_cpu_online(smp_processor_id(), false);
  93         atomic_dec(&waiting_for_crash_ipi);
  94
  95         while (1) {
  96                 cpu_relax();
  97                 wfe();
  98         }
  99 }
 100
 101 void crash_smp_send_stop(void)
 102 {
 103         static int cpus_stopped;
 104         unsigned long msecs;
 105
 106         if (cpus_stopped)
 107                 return;
 108
 109         atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
 110         smp_call_function(machine_crash_nonpanic_core, NULL, false);
 111         msecs = 1000; /* Wait at most a second for the other cpus to stop */
 112         while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 113                 mdelay(1);
 114                 msecs--;
 115         }
 116         if (atomic_read(&waiting_for_crash_ipi) > 0)
 117                 pr_warn("Non-crashing CPUs did not react to IPI\n");
 118
 119         cpus_stopped = 1;
 120 }
 121
 122 static void machine_kexec_mask_interrupts(void)
 123 {
 124         unsigned int i;
 125         struct irq_desc *desc;
 126
 127         for_each_irq_desc(i, desc) {
 128                 struct irq_chip *chip;
 129
 130                 chip = irq_desc_get_chip(desc);
 131                 if (!chip)
 132                         continue;
 133
 134                 if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
 135                         chip->irq_eoi(&desc->irq_data);
 136
 137                 if (chip->irq_mask)
 138                         chip->irq_mask(&desc->irq_data);
 139
 140                 if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
 141                         chip->irq_disable(&desc->irq_data);
 142         }
 143 }
 144
 145 void machine_crash_shutdown(struct pt_regs *regs)
 146 {
 147         local_irq_disable();
 148         crash_smp_send_stop();
 149
 150         crash_save_cpu(regs, smp_processor_id());
 151         machine_kexec_mask_interrupts();
 152
 153         pr_info("Loading crashdump kernel...\n");
 154 }
 155
 156 /*
 157  * Function pointer to optional machine-specific reinitialization
 158  */
 159 void (*kexec_reinit)(void);
 160
 161 void machine_kexec(struct kimage *image)
 162 {
 163         unsigned long page_list, reboot_entry_phys;
 164         void (*reboot_entry)(void);
 165         void *reboot_code_buffer;
 166
 167         /*
 168          * This can only happen if machine_shutdown() failed to disable some
 169          * CPU, and that can only happen if the checks in
 170          * machine_kexec_prepare() were not correct. If this fails, we can't
 171          * reliably kexec anyway, so BUG_ON is appropriate.
 172          */
 173         BUG_ON(num_online_cpus() > 1);
 174
 175         page_list = image->head & PAGE_MASK;
 176
 177         reboot_code_buffer = page_address(image->control_code_page);
 178
 179         /* Prepare parameters for reboot_code_buffer*/
 180         set_kernel_text_rw();
 181         kexec_start_address = image->start;
 182         kexec_indirection_page = page_list;
 183         kexec_mach_type = machine_arch_type;
 184         kexec_boot_atags = image->arch.kernel_r2;
 185
 186         /* copy our kernel relocation code to the control code page */
 187         reboot_entry = fncpy(reboot_code_buffer,
 188                              &relocate_new_kernel,
 189                              relocate_new_kernel_size);
 190
 191         /* get the identity mapping physical address for the reboot code */
 192         reboot_entry_phys = virt_to_idmap(reboot_entry);
 193
 194         pr_info("Bye!\n");
 195
 196         if (kexec_reinit)
 197                 kexec_reinit();
 198
 199         soft_restart(reboot_entry_phys);
 200 }
 201
 202 void arch_crash_save_vmcoreinfo(void)
 203 {
 204 #ifdef CONFIG_ARM_LPAE
 205         VMCOREINFO_CONFIG(ARM_LPAE);
 206 #endif
 207 }