// SPDX-License-Identifier: GPL-2.0/* * machine_kexec.c - handle transition of Linux booting another kernel */ #include <linux/mm.h>#include <linux/kexec.h>#include <linux/delay.h>#include <linux/reboot.h>#include <linux/io.h>#include <linux/irq.h>#include <linux/memblock.h>#include <linux/of_fdt.h>#include <asm/mmu_context.h>#include <asm/cacheflush.h>#include <asm/kexec-internal.h>#include <asm/fncpy.h>#include <asm/mach-types.h>#include <asm/smp_plat.h>#include <asm/system_misc.h>#include <asm/set_memory.h> extern void relocate_new_kernel(void);extern const unsigned int relocate_new_kernel_size; static atomic_t waiting_for_crash_ipi; /* * Provide a dummy crash_notes definition while crash dump arrives to arm. * This prevents breakage of crash_notes attribute in kernel/ksysfs.c. */ int machine_kexec_prepare(struct kimage *image){	struct kexec_segment *current_segment;	__be32 header;	int i, err; 	image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET				     + KEXEC_ARM_ATAGS_OFFSET; 	/*	 * Validate that if the current HW supports SMP, then the SW supports	 * and implements CPU hotplug for the current HW. If not, we won't be	 * able to kexec reliably, so fail the prepare operation.	 */	if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&	    !platform_can_cpu_hotplug())		return -EINVAL; 	/*	 * No segment at default ATAGs address. try to locate	 * a dtb using magic.	 */	for (i = 0; i < image->nr_segments; i++) {		current_segment = &image->segment[i]; 		if (!memblock_is_region_memory(idmap_to_phys(current_segment->mem),					       current_segment->memsz))			return -EINVAL; 		err = get_user(header, (__be32*)current_segment->buf);		if (err)			return err; 		if (header == cpu_to_be32(OF_DT_HEADER))			image->arch.kernel_r2 = current_segment->mem;	}	return 0;} void machine_kexec_cleanup(struct kimage *image){} static void machine_crash_nonpanic_core(void *unused){	struct pt_regs regs; 	local_fiq_disable(); 	crash_setup_regs(&regs, get_irq_regs());	printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",	       smp_processor_id());	crash_save_cpu(&regs, smp_processor_id());	flush_cache_all(); 	set_cpu_online(smp_processor_id(), false);	atomic_dec(&waiting_for_crash_ipi); 	while (1) {		cpu_relax();		wfe();	}} static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =	CSD_INIT(machine_crash_nonpanic_core, NULL); void crash_smp_send_stop(void){	static int cpus_stopped;	unsigned long msecs;	call_single_data_t *csd;	int cpu, this_cpu = raw_smp_processor_id(); 	if (cpus_stopped)		return; 	atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);	for_each_online_cpu(cpu) {		if (cpu == this_cpu)			continue; 		csd = &per_cpu(cpu_stop_csd, cpu);		smp_call_function_single_async(cpu, csd);	} 	msecs = 1000; /* Wait at most a second for the other cpus to stop */	while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {		mdelay(1);		msecs--;	}	if (atomic_read(&waiting_for_crash_ipi) > 0)		pr_warn("Non-crashing CPUs did not react to IPI\n"); 	cpus_stopped = 1;} void machine_crash_shutdown(struct pt_regs *regs){	local_irq_disable();	crash_smp_send_stop(); 	crash_save_cpu(regs, smp_processor_id());	machine_kexec_mask_interrupts(); 	pr_info("Loading crashdump kernel...\n");} void machine_kexec(struct kimage *image){	unsigned long page_list, reboot_entry_phys;	struct kexec_relocate_data *data;	void (*reboot_entry)(void);	void *reboot_code_buffer; 	/*	 * This can only happen if machine_shutdown() failed to disable some	 * CPU, and that can only happen if the checks in	 * machine_kexec_prepare() were not correct. If this fails, we can't	 * reliably kexec anyway, so BUG_ON is appropriate.	 */	BUG_ON(num_online_cpus() > 1); 	page_list = image->head & PAGE_MASK; 	reboot_code_buffer = page_address(image->control_code_page); 	/* copy our kernel relocation code to the control code page */	reboot_entry = fncpy(reboot_code_buffer,			     &relocate_new_kernel,			     relocate_new_kernel_size); 	data = reboot_code_buffer + relocate_new_kernel_size;	data->kexec_start_address = image->start;	data->kexec_indirection_page = page_list;	data->kexec_mach_type = machine_arch_type;	data->kexec_r2 = image->arch.kernel_r2; 	/* get the identity mapping physical address for the reboot code */	reboot_entry_phys = virt_to_idmap(reboot_entry); 	pr_info("Bye!\n"); 	soft_restart(reboot_entry_phys);}