machine_kexec.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * machine_kexec.c for kexec
 * Created by <nschichan@corp.free.fr> on Thu Oct 12 15:15:06 2006
 */
#include <linux/compiler.h>
#include <linux/kexec.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/libfdt.h>

#include <asm/cacheflush.h>
#include <asm/page.h>

extern const unsigned char relocate_new_kernel[];
extern const size_t relocate_new_kernel_size;

extern unsigned long kexec_start_address;
extern unsigned long kexec_indirection_page;

static unsigned long reboot_code_buffer;

#ifdef CONFIG_SMP
static void (*relocated_kexec_smp_wait)(void *);

atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
void (*_crash_smp_send_stop)(void) = NULL;
#endif

void (*_machine_kexec_shutdown)(void) = NULL;
void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;

static void kexec_image_info(const struct kimage *kimage)
{
	unsigned long i;

	pr_debug("kexec kimage info:\n");
	pr_debug("  type:        %d\n", kimage->type);
	pr_debug("  start:       %lx\n", kimage->start);
	pr_debug("  head:        %lx\n", kimage->head);
	pr_debug("  nr_segments: %lu\n", kimage->nr_segments);

	for (i = 0; i < kimage->nr_segments; i++) {
		pr_debug("    segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
			i,
			kimage->segment[i].mem,
			kimage->segment[i].mem + kimage->segment[i].memsz,
			(unsigned long)kimage->segment[i].memsz,
			(unsigned long)kimage->segment[i].memsz /  PAGE_SIZE);
	}
}

#ifdef CONFIG_UHI_BOOT

static int uhi_machine_kexec_prepare(struct kimage *kimage)
{
	int i;

	/*
	 * In case DTB file is not passed to the new kernel, a flat device
	 * tree will be created by kexec tool. It holds modified command
	 * line for the new kernel.
	 */
	for (i = 0; i < kimage->nr_segments; i++) {
		struct fdt_header fdt;

		if (kimage->segment[i].memsz <= sizeof(fdt))
			continue;

		if (copy_from_user(&fdt, kimage->segment[i].buf, sizeof(fdt)))
			continue;

		if (fdt_check_header(&fdt))
			continue;

		kexec_args[0] = -2;
		kexec_args[1] = (unsigned long)
			phys_to_virt((unsigned long)kimage->segment[i].mem);
		break;
	}

	return 0;
}

int (*_machine_kexec_prepare)(struct kimage *) = uhi_machine_kexec_prepare;

#else

int (*_machine_kexec_prepare)(struct kimage *) = NULL;

#endif /* CONFIG_UHI_BOOT */

int
machine_kexec_prepare(struct kimage *kimage)
{
#ifdef CONFIG_SMP
	if (!kexec_nonboot_cpu_func())
		return -EINVAL;
#endif

	kexec_image_info(kimage);

	if (_machine_kexec_prepare)
		return _machine_kexec_prepare(kimage);

	return 0;
}

void
machine_kexec_cleanup(struct kimage *kimage)
{
}

#ifdef CONFIG_SMP
static void kexec_shutdown_secondary(void *param)
{
	int cpu = smp_processor_id();

	if (!cpu_online(cpu))
		return;

	/* We won't be sent IPIs any more. */
	set_cpu_online(cpu, false);

	local_irq_disable();
	while (!atomic_read(&kexec_ready_to_reboot))
		cpu_relax();

	kexec_reboot();

	/* NOTREACHED */
}
#endif

void
machine_shutdown(void)
{
	if (_machine_kexec_shutdown)
		_machine_kexec_shutdown();

#ifdef CONFIG_SMP
	smp_call_function(kexec_shutdown_secondary, NULL, 0);

	while (num_online_cpus() > 1) {
		cpu_relax();
		mdelay(1);
	}
#endif
}

void
machine_crash_shutdown(struct pt_regs *regs)
{
	if (_machine_crash_shutdown)
		_machine_crash_shutdown(regs);
	else
		default_machine_crash_shutdown(regs);
}

#ifdef CONFIG_SMP
void kexec_nonboot_cpu_jump(void)
{
	local_flush_icache_range((unsigned long)relocated_kexec_smp_wait,
				 reboot_code_buffer + relocate_new_kernel_size);

	relocated_kexec_smp_wait(NULL);
}
#endif

void kexec_reboot(void)
{
	void (*do_kexec)(void) __noreturn;

	/*
	 * We know we were online, and there will be no incoming IPIs at
	 * this point. Mark online again before rebooting so that the crash
	 * analysis tool will see us correctly.
	 */
	set_cpu_online(smp_processor_id(), true);

	/* Ensure remote CPUs observe that we're online before rebooting. */
	smp_mb__after_atomic();

#ifdef CONFIG_SMP
	if (smp_processor_id() > 0) {
		/*
		 * Instead of cpu_relax() or wait, this is needed for kexec
		 * smp reboot. Kdump usually doesn't require an smp new
		 * kernel, but kexec may do.
		 */
		kexec_nonboot_cpu();

		/* NOTREACHED */
	}
#endif

	/*
	 * Make sure we get correct instructions written by the
	 * machine_kexec() CPU.
	 */
	local_flush_icache_range(reboot_code_buffer,
				 reboot_code_buffer + relocate_new_kernel_size);

	do_kexec = (void *)reboot_code_buffer;
	do_kexec();
}

void
machine_kexec(struct kimage *image)
{
	unsigned long entry;
	unsigned long *ptr;

	reboot_code_buffer =
	  (unsigned long)page_address(image->control_code_page);

	kexec_start_address =
		(unsigned long) phys_to_virt(image->start);

	if (image->type == KEXEC_TYPE_DEFAULT) {
		kexec_indirection_page =
			(unsigned long) phys_to_virt(image->head & PAGE_MASK);
	} else {
		kexec_indirection_page = (unsigned long)&image->head;
	}

	memcpy((void*)reboot_code_buffer, relocate_new_kernel,
	       relocate_new_kernel_size);

	/*
	 * The generic kexec code builds a page list with physical
	 * addresses. they are directly accessible through KSEG0 (or
	 * CKSEG0 or XPHYS if on 64bit system), hence the
	 * phys_to_virt() call.
	 */
	for (ptr = &image->head; (entry = *ptr) && !(entry &IND_DONE);
	     ptr = (entry & IND_INDIRECTION) ?
	       phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
		if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
		    *ptr & IND_DESTINATION)
			*ptr = (unsigned long) phys_to_virt(*ptr);
	}

	/* Mark offline BEFORE disabling local irq. */
	set_cpu_online(smp_processor_id(), false);

	/*
	 * we do not want to be bothered.
	 */
	local_irq_disable();

	printk("Will call new kernel at %08lx\n", image->start);
	printk("Bye ...\n");
	/* Make reboot code buffer available to the boot CPU. */
	__flush_cache_all();
#ifdef CONFIG_SMP
	/* All secondary cpus now may jump to kexec_wait cycle */
	relocated_kexec_smp_wait = reboot_code_buffer +
		(void *)(kexec_smp_wait - relocate_new_kernel);
	smp_wmb();
	atomic_set(&kexec_ready_to_reboot, 1);
#endif
	kexec_reboot();
}