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
 23extern void relocate_new_kernel(void);
 24extern const unsigned int relocate_new_kernel_size;
 25
 26static 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
 33int 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
 72void machine_kexec_cleanup(struct kimage *image)
 73{
 74}
 75
 76static 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
 97static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
 98	CSD_INIT(machine_crash_nonpanic_core, NULL);
 99
100void 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
130void 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
141void 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}