core.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Code to handle transition of Linux booting another kernel.
 *
 * Copyright (C) 2002-2003 Eric Biederman  <[email protected]>
 * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
 * Copyright (C) 2005 IBM Corporation.
 */

#include <linux/kexec.h>
#include <linux/reboot.h>
#include <linux/threads.h>
#include <linux/memblock.h>
#include <linux/of.h>
#include <linux/irq.h>
#include <linux/ftrace.h>

#include <asm/kdump.h>
#include <asm/machdep.h>
#include <asm/pgalloc.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/firmware.h>

#define cpu_to_be_ulong __PASTE(cpu_to_be, BITS_PER_LONG)

#ifdef CONFIG_CRASH_DUMP
void machine_crash_shutdown(struct pt_regs *regs)
{
	default_machine_crash_shutdown(regs);
}
#endif

void machine_kexec_cleanup(struct kimage *image)
{
}

/*
 * Do not allocate memory (or fail in any way) in machine_kexec().
 * We are past the point of no return, committed to rebooting now.
 */
void machine_kexec(struct kimage *image)
{
	int save_ftrace_enabled;

	save_ftrace_enabled = __ftrace_enabled_save();
	this_cpu_disable_ftrace();

	if (ppc_md.machine_kexec)
		ppc_md.machine_kexec(image);
	else
		default_machine_kexec(image);

	this_cpu_enable_ftrace();
	__ftrace_enabled_restore(save_ftrace_enabled);

	/* Fall back to normal restart if we're still alive. */
	machine_restart(NULL);
	for(;;);
}

#ifdef CONFIG_CRASH_RESERVE

static unsigned long long crashk_cma_size;

static unsigned long long __init get_crash_base(unsigned long long crash_base)
{

#ifndef CONFIG_NONSTATIC_KERNEL
	if (crash_base != KDUMP_KERNELBASE)
		printk("Crash kernel location must be 0x%x\n",
				KDUMP_KERNELBASE);

	return KDUMP_KERNELBASE;
#else
	unsigned long long crash_base_align;

	if (!crash_base) {
#ifdef CONFIG_PPC64
		/*
		 * On the LPAR platform place the crash kernel to mid of
		 * RMA size (max. of 512MB) to ensure the crash kernel
		 * gets enough space to place itself and some stack to be
		 * in the first segment. At the same time normal kernel
		 * also get enough space to allocate memory for essential
		 * system resource in the first segment. Keep the crash
		 * kernel starts at 128MB offset on other platforms.
		 */
		if (firmware_has_feature(FW_FEATURE_LPAR))
			crash_base = min_t(u64, ppc64_rma_size / 2, SZ_512M);
		else
			crash_base = min_t(u64, ppc64_rma_size / 2, SZ_128M);
#else
		crash_base = KDUMP_KERNELBASE;
#endif
	}

	crash_base_align = PAGE_ALIGN(crash_base);
	if (crash_base != crash_base_align)
		pr_warn("Crash kernel base must be aligned to 0x%lx\n", PAGE_SIZE);

	return crash_base_align;
#endif
}

void __init arch_reserve_crashkernel(void)
{
	unsigned long long crash_size, crash_base, crash_end;
	unsigned long long kernel_start, kernel_size;
	unsigned long long total_mem_sz;
	int ret;

	total_mem_sz = memory_limit ? memory_limit : memblock_phys_mem_size();

	/* use common parsing */
	ret = parse_crashkernel(boot_command_line, total_mem_sz, &crash_size,
				&crash_base, NULL, &crashk_cma_size, NULL);

	if (ret)
		return;

	crash_base = get_crash_base(crash_base);
	crash_end = crash_base + crash_size - 1;

	kernel_start = __pa(_stext);
	kernel_size = _end - _stext;

	/* The crash region must not overlap the current kernel */
	if ((kernel_start + kernel_size > crash_base) && (kernel_start <= crash_end)) {
		pr_warn("Crash kernel can not overlap current kernel\n");
		return;
	}

	reserve_crashkernel_generic(crash_size, crash_base, 0, false);
}

void __init kdump_cma_reserve(void)
{
	if (crashk_cma_size)
		reserve_crashkernel_cma(crashk_cma_size);
}

int __init overlaps_crashkernel(unsigned long start, unsigned long size)
{
	return (start + size) > crashk_res.start && start <= crashk_res.end;
}

/* Values we need to export to the second kernel via the device tree. */
static phys_addr_t crashk_base;
static phys_addr_t crashk_size;
static unsigned long long mem_limit;

static struct property crashk_base_prop = {
	.name = "linux,crashkernel-base",
	.length = sizeof(phys_addr_t),
	.value = &crashk_base
};

static struct property crashk_size_prop = {
	.name = "linux,crashkernel-size",
	.length = sizeof(phys_addr_t),
	.value = &crashk_size,
};

static struct property memory_limit_prop = {
	.name = "linux,memory-limit",
	.length = sizeof(unsigned long long),
	.value = &mem_limit,
};

static void __init export_crashk_values(struct device_node *node)
{
	/* There might be existing crash kernel properties, but we can't
	 * be sure what's in them, so remove them. */
	of_remove_property(node, of_find_property(node,
				"linux,crashkernel-base", NULL));
	of_remove_property(node, of_find_property(node,
				"linux,crashkernel-size", NULL));

	if (crashk_res.start != 0) {
		crashk_base = cpu_to_be_ulong(crashk_res.start),
		of_add_property(node, &crashk_base_prop);
		crashk_size = cpu_to_be_ulong(resource_size(&crashk_res));
		of_add_property(node, &crashk_size_prop);
	}

	/*
	 * memory_limit is required by the kexec-tools to limit the
	 * crash regions to the actual memory used.
	 */
	mem_limit = cpu_to_be_ulong(memory_limit);
	of_update_property(node, &memory_limit_prop);
}
#endif /* CONFIG_CRASH_RESERVE */

static phys_addr_t kernel_end;

static struct property kernel_end_prop = {
	.name = "linux,kernel-end",
	.length = sizeof(phys_addr_t),
	.value = &kernel_end,
};

static int __init kexec_setup(void)
{
	struct device_node *node;

	node = of_find_node_by_path("/chosen");
	if (!node)
		return -ENOENT;

	/* remove any stale properties so ours can be found */
	of_remove_property(node, of_find_property(node, kernel_end_prop.name,
						  NULL));

	/* information needed by userspace when using default_machine_kexec */
	kernel_end = cpu_to_be_ulong(__pa(_end));
	of_add_property(node, &kernel_end_prop);

#ifdef CONFIG_CRASH_RESERVE
	export_crashk_values(node);
#endif
	of_node_put(node);
	return 0;
}
late_initcall(kexec_setup);