1 files changed, 693 insertions, 0 deletions

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
new file mode 100644
index 000000000000..99dac1aa972a
--- /dev/null
+++ b/kernel/crash_core.c
@@ -0,0 +1,693 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * crash.c - kernel crash support code.
+ * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/buildid.h>
+#include <linux/init.h>
+#include <linux/utsname.h>
+#include <linux/vmalloc.h>
+#include <linux/sizes.h>
+#include <linux/kexec.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/cpuhotplug.h>
+#include <linux/memblock.h>
+#include <linux/kmemleak.h>
+#include <linux/crash_core.h>
+#include <linux/reboot.h>
+#include <linux/btf.h>
+#include <linux/objtool.h>
+#include <linux/delay.h>
+#include <linux/panic.h>
+
+#include <asm/page.h>
+#include <asm/sections.h>
+
+#include <crypto/sha1.h>
+
+#include "kallsyms_internal.h"
+#include "kexec_internal.h"
+
+/* Per cpu memory for storing cpu states in case of system crash. */
+note_buf_t __percpu *crash_notes;
+
+/* time to wait for possible DMA to finish before starting the kdump kernel
+ * when a CMA reservation is used
+ */
+#define CMA_DMA_TIMEOUT_SEC 10
+
+#ifdef CONFIG_CRASH_DUMP
+
+int kimage_crash_copy_vmcoreinfo(struct kimage *image)
+{
+	struct page *vmcoreinfo_page;
+	void *safecopy;
+
+	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
+		return 0;
+	if (image->type != KEXEC_TYPE_CRASH)
+		return 0;
+
+	/*
+	 * For kdump, allocate one vmcoreinfo safe copy from the
+	 * crash memory. as we have arch_kexec_protect_crashkres()
+	 * after kexec syscall, we naturally protect it from write
+	 * (even read) access under kernel direct mapping. But on
+	 * the other hand, we still need to operate it when crash
+	 * happens to generate vmcoreinfo note, hereby we rely on
+	 * vmap for this purpose.
+	 */
+	vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
+	if (!vmcoreinfo_page) {
+		pr_warn("Could not allocate vmcoreinfo buffer\n");
+		return -ENOMEM;
+	}
+	safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
+	if (!safecopy) {
+		pr_warn("Could not vmap vmcoreinfo buffer\n");
+		return -ENOMEM;
+	}
+
+	image->vmcoreinfo_data_copy = safecopy;
+	crash_update_vmcoreinfo_safecopy(safecopy);
+
+	return 0;
+}
+
+
+
+int kexec_should_crash(struct task_struct *p)
+{
+	/*
+	 * If crash_kexec_post_notifiers is enabled, don't run
+	 * crash_kexec() here yet, which must be run after panic
+	 * notifiers in panic().
+	 */
+	if (crash_kexec_post_notifiers)
+		return 0;
+	/*
+	 * There are 4 panic() calls in make_task_dead() path, each of which
+	 * corresponds to each of these 4 conditions.
+	 */
+	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
+		return 1;
+	return 0;
+}
+
+int kexec_crash_loaded(void)
+{
+	return !!kexec_crash_image;
+}
+EXPORT_SYMBOL_GPL(kexec_crash_loaded);
+
+static void crash_cma_clear_pending_dma(void)
+{
+	if (!crashk_cma_cnt)
+		return;
+
+	mdelay(CMA_DMA_TIMEOUT_SEC * 1000);
+}
+
+/*
+ * No panic_cpu check version of crash_kexec().  This function is called
+ * only when panic_cpu holds the current CPU number; this is the only CPU
+ * which processes crash_kexec routines.
+ */
+void __noclone __crash_kexec(struct pt_regs *regs)
+{
+	/* Take the kexec_lock here to prevent sys_kexec_load
+	 * running on one cpu from replacing the crash kernel
+	 * we are using after a panic on a different cpu.
+	 *
+	 * If the crash kernel was not located in a fixed area
+	 * of memory the xchg(&kexec_crash_image) would be
+	 * sufficient.  But since I reuse the memory...
+	 */
+	if (kexec_trylock()) {
+		if (kexec_crash_image) {
+			struct pt_regs fixed_regs;
+
+			crash_setup_regs(&fixed_regs, regs);
+			crash_save_vmcoreinfo();
+			machine_crash_shutdown(&fixed_regs);
+			crash_cma_clear_pending_dma();
+			machine_kexec(kexec_crash_image);
+		}
+		kexec_unlock();
+	}
+}
+STACK_FRAME_NON_STANDARD(__crash_kexec);
+
+__bpf_kfunc void crash_kexec(struct pt_regs *regs)
+{
+	if (panic_try_start()) {
+		/* This is the 1st CPU which comes here, so go ahead. */
+		__crash_kexec(regs);
+
+		/*
+		 * Reset panic_cpu to allow another panic()/crash_kexec()
+		 * call.
+		 */
+		panic_reset();
+	}
+}
+
+static inline resource_size_t crash_resource_size(const struct resource *res)
+{
+	return !res->end ? 0 : resource_size(res);
+}
+
+
+
+
+int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
+			  void **addr, unsigned long *sz)
+{
+	Elf64_Ehdr *ehdr;
+	Elf64_Phdr *phdr;
+	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
+	unsigned char *buf;
+	unsigned int cpu, i;
+	unsigned long long notes_addr;
+	unsigned long mstart, mend;
+
+	/* extra phdr for vmcoreinfo ELF note */
+	nr_phdr = nr_cpus + 1;
+	nr_phdr += mem->nr_ranges;
+
+	/*
+	 * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
+	 * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
+	 * I think this is required by tools like gdb. So same physical
+	 * memory will be mapped in two ELF headers. One will contain kernel
+	 * text virtual addresses and other will have __va(physical) addresses.
+	 */
+
+	nr_phdr++;
+	elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
+	elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
+
+	buf = vzalloc(elf_sz);
+	if (!buf)
+		return -ENOMEM;
+
+	ehdr = (Elf64_Ehdr *)buf;
+	phdr = (Elf64_Phdr *)(ehdr + 1);
+	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
+	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
+	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
+	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
+	ehdr->e_ident[EI_OSABI] = ELF_OSABI;
+	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
+	ehdr->e_type = ET_CORE;
+	ehdr->e_machine = ELF_ARCH;
+	ehdr->e_version = EV_CURRENT;
+	ehdr->e_phoff = sizeof(Elf64_Ehdr);
+	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
+	ehdr->e_phentsize = sizeof(Elf64_Phdr);
+
+	/* Prepare one phdr of type PT_NOTE for each possible CPU */
+	for_each_possible_cpu(cpu) {
+		phdr->p_type = PT_NOTE;
+		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
+		phdr->p_offset = phdr->p_paddr = notes_addr;
+		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
+		(ehdr->e_phnum)++;
+		phdr++;
+	}
+
+	/* Prepare one PT_NOTE header for vmcoreinfo */
+	phdr->p_type = PT_NOTE;
+	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
+	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
+	(ehdr->e_phnum)++;
+	phdr++;
+
+	/* Prepare PT_LOAD type program header for kernel text region */
+	if (need_kernel_map) {
+		phdr->p_type = PT_LOAD;
+		phdr->p_flags = PF_R|PF_W|PF_X;
+		phdr->p_vaddr = (unsigned long) _text;
+		phdr->p_filesz = phdr->p_memsz = _end - _text;
+		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
+		ehdr->e_phnum++;
+		phdr++;
+	}
+
+	/* Go through all the ranges in mem->ranges[] and prepare phdr */
+	for (i = 0; i < mem->nr_ranges; i++) {
+		mstart = mem->ranges[i].start;
+		mend = mem->ranges[i].end;
+
+		phdr->p_type = PT_LOAD;
+		phdr->p_flags = PF_R|PF_W|PF_X;
+		phdr->p_offset  = mstart;
+
+		phdr->p_paddr = mstart;
+		phdr->p_vaddr = (unsigned long) __va(mstart);
+		phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
+		phdr->p_align = 0;
+		ehdr->e_phnum++;
+#ifdef CONFIG_KEXEC_FILE
+		kexec_dprintk("Crash PT_LOAD ELF header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
+			      phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
+			      ehdr->e_phnum, phdr->p_offset);
+#endif
+		phdr++;
+	}
+
+	*addr = buf;
+	*sz = elf_sz;
+	return 0;
+}
+
+/**
+ * crash_exclude_mem_range - exclude a mem range for existing ranges
+ * @mem: mem->range contains an array of ranges sorted in ascending order
+ * @mstart: the start of to-be-excluded range
+ * @mend: the start of to-be-excluded range
+ *
+ * If you are unsure if a range split will happen, to avoid function call
+ * failure because of -ENOMEM, always make sure
+ *    mem->max_nr_ranges == mem->nr_ranges + 1
+ * before calling the function each time.
+ *
+ * returns 0 if a memory range is excluded successfully
+ * return -ENOMEM if mem->ranges doesn't have space to hold split ranges
+ */
+int crash_exclude_mem_range(struct crash_mem *mem,
+			    unsigned long long mstart, unsigned long long mend)
+{
+	int i;
+	unsigned long long start, end, p_start, p_end;
+
+	for (i = 0; i < mem->nr_ranges; i++) {
+		start = mem->ranges[i].start;
+		end = mem->ranges[i].end;
+		p_start = mstart;
+		p_end = mend;
+
+		if (p_start > end)
+			continue;
+
+		/*
+		 * Because the memory ranges in mem->ranges are stored in
+		 * ascending order, when we detect `p_end < start`, we can
+		 * immediately exit the for loop, as the subsequent memory
+		 * ranges will definitely be outside the range we are looking
+		 * for.
+		 */
+		if (p_end < start)
+			break;
+
+		/* Truncate any area outside of range */
+		if (p_start < start)
+			p_start = start;
+		if (p_end > end)
+			p_end = end;
+
+		/* Found completely overlapping range */
+		if (p_start == start && p_end == end) {
+			memmove(&mem->ranges[i], &mem->ranges[i + 1],
+				(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
+			i--;
+			mem->nr_ranges--;
+		} else if (p_start > start && p_end < end) {
+			/* Split original range */
+			if (mem->nr_ranges >= mem->max_nr_ranges)
+				return -ENOMEM;
+
+			memmove(&mem->ranges[i + 2], &mem->ranges[i + 1],
+				(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
+
+			mem->ranges[i].end = p_start - 1;
+			mem->ranges[i + 1].start = p_end + 1;
+			mem->ranges[i + 1].end = end;
+
+			i++;
+			mem->nr_ranges++;
+		} else if (p_start != start)
+			mem->ranges[i].end = p_start - 1;
+		else
+			mem->ranges[i].start = p_end + 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crash_exclude_mem_range);
+
+ssize_t crash_get_memory_size(void)
+{
+	ssize_t size = 0;
+
+	if (!kexec_trylock())
+		return -EBUSY;
+
+	size += crash_resource_size(&crashk_res);
+	size += crash_resource_size(&crashk_low_res);
+
+	kexec_unlock();
+	return size;
+}
+
+static int __crash_shrink_memory(struct resource *old_res,
+				 unsigned long new_size)
+{
+	struct resource *ram_res;
+
+	ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
+	if (!ram_res)
+		return -ENOMEM;
+
+	ram_res->start = old_res->start + new_size;
+	ram_res->end   = old_res->end;
+	ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
+	ram_res->name  = "System RAM";
+
+	if (!new_size) {
+		release_resource(old_res);
+		old_res->start = 0;
+		old_res->end   = 0;
+	} else {
+		old_res->end = ram_res->start - 1;
+	}
+
+	crash_free_reserved_phys_range(ram_res->start, ram_res->end);
+	insert_resource(&iomem_resource, ram_res);
+
+	return 0;
+}
+
+int crash_shrink_memory(unsigned long new_size)
+{
+	int ret = 0;
+	unsigned long old_size, low_size;
+
+	if (!kexec_trylock())
+		return -EBUSY;
+
+	if (kexec_crash_image) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+
+	low_size = crash_resource_size(&crashk_low_res);
+	old_size = crash_resource_size(&crashk_res) + low_size;
+	new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);
+	if (new_size >= old_size) {
+		ret = (new_size == old_size) ? 0 : -EINVAL;
+		goto unlock;
+	}
+
+	/*
+	 * (low_size > new_size) implies that low_size is greater than zero.
+	 * This also means that if low_size is zero, the else branch is taken.
+	 *
+	 * If low_size is greater than 0, (low_size > new_size) indicates that
+	 * crashk_low_res also needs to be shrunken. Otherwise, only crashk_res
+	 * needs to be shrunken.
+	 */
+	if (low_size > new_size) {
+		ret = __crash_shrink_memory(&crashk_res, 0);
+		if (ret)
+			goto unlock;
+
+		ret = __crash_shrink_memory(&crashk_low_res, new_size);
+	} else {
+		ret = __crash_shrink_memory(&crashk_res, new_size - low_size);
+	}
+
+	/* Swap crashk_res and crashk_low_res if needed */
+	if (!crashk_res.end && crashk_low_res.end) {
+		crashk_res.start = crashk_low_res.start;
+		crashk_res.end   = crashk_low_res.end;
+		release_resource(&crashk_low_res);
+		crashk_low_res.start = 0;
+		crashk_low_res.end   = 0;
+		insert_resource(&iomem_resource, &crashk_res);
+	}
+
+unlock:
+	kexec_unlock();
+	return ret;
+}
+
+void crash_save_cpu(struct pt_regs *regs, int cpu)
+{
+	struct elf_prstatus prstatus;
+	u32 *buf;
+
+	if ((cpu < 0) || (cpu >= nr_cpu_ids))
+		return;
+
+	/* Using ELF notes here is opportunistic.
+	 * I need a well defined structure format
+	 * for the data I pass, and I need tags
+	 * on the data to indicate what information I have
+	 * squirrelled away.  ELF notes happen to provide
+	 * all of that, so there is no need to invent something new.
+	 */
+	buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
+	if (!buf)
+		return;
+	memset(&prstatus, 0, sizeof(prstatus));
+	prstatus.common.pr_pid = current->pid;
+	elf_core_copy_regs(&prstatus.pr_reg, regs);
+	buf = append_elf_note(buf, NN_PRSTATUS, NT_PRSTATUS,
+			      &prstatus, sizeof(prstatus));
+	final_note(buf);
+}
+
+
+
+static int __init crash_notes_memory_init(void)
+{
+	/* Allocate memory for saving cpu registers. */
+	size_t size, align;
+
+	/*
+	 * crash_notes could be allocated across 2 vmalloc pages when percpu
+	 * is vmalloc based . vmalloc doesn't guarantee 2 continuous vmalloc
+	 * pages are also on 2 continuous physical pages. In this case the
+	 * 2nd part of crash_notes in 2nd page could be lost since only the
+	 * starting address and size of crash_notes are exported through sysfs.
+	 * Here round up the size of crash_notes to the nearest power of two
+	 * and pass it to __alloc_percpu as align value. This can make sure
+	 * crash_notes is allocated inside one physical page.
+	 */
+	size = sizeof(note_buf_t);
+	align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE);
+
+	/*
+	 * Break compile if size is bigger than PAGE_SIZE since crash_notes
+	 * definitely will be in 2 pages with that.
+	 */
+	BUILD_BUG_ON(size > PAGE_SIZE);
+
+	crash_notes = __alloc_percpu(size, align);
+	if (!crash_notes) {
+		pr_warn("Memory allocation for saving cpu register states failed\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+subsys_initcall(crash_notes_memory_init);
+
+#endif /*CONFIG_CRASH_DUMP*/
+
+#ifdef CONFIG_CRASH_HOTPLUG
+#undef pr_fmt
+#define pr_fmt(fmt) "crash hp: " fmt
+
+/*
+ * Different than kexec/kdump loading/unloading/jumping/shrinking which
+ * usually rarely happen, there will be many crash hotplug events notified
+ * during one short period, e.g one memory board is hot added and memory
+ * regions are online. So mutex lock  __crash_hotplug_lock is used to
+ * serialize the crash hotplug handling specifically.
+ */
+static DEFINE_MUTEX(__crash_hotplug_lock);
+#define crash_hotplug_lock() mutex_lock(&__crash_hotplug_lock)
+#define crash_hotplug_unlock() mutex_unlock(&__crash_hotplug_lock)
+
+/*
+ * This routine utilized when the crash_hotplug sysfs node is read.
+ * It reflects the kernel's ability/permission to update the kdump
+ * image directly.
+ */
+int crash_check_hotplug_support(void)
+{
+	int rc = 0;
+
+	crash_hotplug_lock();
+	/* Obtain lock while reading crash information */
+	if (!kexec_trylock()) {
+		if (!kexec_in_progress)
+			pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
+		crash_hotplug_unlock();
+		return 0;
+	}
+	if (kexec_crash_image) {
+		rc = kexec_crash_image->hotplug_support;
+	}
+	/* Release lock now that update complete */
+	kexec_unlock();
+	crash_hotplug_unlock();
+
+	return rc;
+}
+
+/*
+ * To accurately reflect hot un/plug changes of CPU and Memory resources
+ * (including onling and offlining of those resources), the relevant
+ * kexec segments must be updated with latest CPU and Memory resources.
+ *
+ * Architectures must ensure two things for all segments that need
+ * updating during hotplug events:
+ *
+ * 1. Segments must be large enough to accommodate a growing number of
+ *    resources.
+ * 2. Exclude the segments from SHA verification.
+ *
+ * For example, on most architectures, the elfcorehdr (which is passed
+ * to the crash kernel via the elfcorehdr= parameter) must include the
+ * new list of CPUs and memory. To make changes to the elfcorehdr, it
+ * should be large enough to permit a growing number of CPU and Memory
+ * resources. One can estimate the elfcorehdr memory size based on
+ * NR_CPUS_DEFAULT and CRASH_MAX_MEMORY_RANGES. The elfcorehdr is
+ * excluded from SHA verification by default if the architecture
+ * supports crash hotplug.
+ */
+static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu, void *arg)
+{
+	struct kimage *image;
+
+	crash_hotplug_lock();
+	/* Obtain lock while changing crash information */
+	if (!kexec_trylock()) {
+		if (!kexec_in_progress)
+			pr_info("kexec_trylock() failed, kdump image may be inaccurate\n");
+		crash_hotplug_unlock();
+		return;
+	}
+
+	/* Check kdump is not loaded */
+	if (!kexec_crash_image)
+		goto out;
+
+	image = kexec_crash_image;
+
+	/* Check that kexec segments update is permitted */
+	if (!image->hotplug_support)
+		goto out;
+
+	if (hp_action == KEXEC_CRASH_HP_ADD_CPU ||
+		hp_action == KEXEC_CRASH_HP_REMOVE_CPU)
+		pr_debug("hp_action %u, cpu %u\n", hp_action, cpu);
+	else
+		pr_debug("hp_action %u\n", hp_action);
+
+	/*
+	 * The elfcorehdr_index is set to -1 when the struct kimage
+	 * is allocated. Find the segment containing the elfcorehdr,
+	 * if not already found.
+	 */
+	if (image->elfcorehdr_index < 0) {
+		unsigned long mem;
+		unsigned char *ptr;
+		unsigned int n;
+
+		for (n = 0; n < image->nr_segments; n++) {
+			mem = image->segment[n].mem;
+			ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT));
+			if (ptr) {
+				/* The segment containing elfcorehdr */
+				if (memcmp(ptr, ELFMAG, SELFMAG) == 0)
+					image->elfcorehdr_index = (int)n;
+				kunmap_local(ptr);
+			}
+		}
+	}
+
+	if (image->elfcorehdr_index < 0) {
+		pr_err("unable to locate elfcorehdr segment");
+		goto out;
+	}
+
+	/* Needed in order for the segments to be updated */
+	arch_kexec_unprotect_crashkres();
+
+	/* Differentiate between normal load and hotplug update */
+	image->hp_action = hp_action;
+
+	/* Now invoke arch-specific update handler */
+	arch_crash_handle_hotplug_event(image, arg);
+
+	/* No longer handling a hotplug event */
+	image->hp_action = KEXEC_CRASH_HP_NONE;
+	image->elfcorehdr_updated = true;
+
+	/* Change back to read-only */
+	arch_kexec_protect_crashkres();
+
+	/* Errors in the callback is not a reason to rollback state */
+out:
+	/* Release lock now that update complete */
+	kexec_unlock();
+	crash_hotplug_unlock();
+}
+
+static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *arg)
+{
+	switch (val) {
+	case MEM_ONLINE:
+		crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY,
+			KEXEC_CRASH_HP_INVALID_CPU, arg);
+		break;
+
+	case MEM_OFFLINE:
+		crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY,
+			KEXEC_CRASH_HP_INVALID_CPU, arg);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block crash_memhp_nb = {
+	.notifier_call = crash_memhp_notifier,
+	.priority = 0
+};
+
+static int crash_cpuhp_online(unsigned int cpu)
+{
+	crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu, NULL);
+	return 0;
+}
+
+static int crash_cpuhp_offline(unsigned int cpu)
+{
+	crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu, NULL);
+	return 0;
+}
+
+static int __init crash_hotplug_init(void)
+{
+	int result = 0;
+
+	if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
+		register_memory_notifier(&crash_memhp_nb);
+
+	if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
+		result = cpuhp_setup_state_nocalls(CPUHP_BP_PREPARE_DYN,
+			"crash/cpuhp", crash_cpuhp_online, crash_cpuhp_offline);
+	}
+
+	return result;
+}
+
+subsys_initcall(crash_hotplug_init);
+#endif