// SPDX-License-Identifier: GPL-2.0-only /* * kexec.c - kexec system call core code. * Copyright (C) 2002-2004 Eric Biederman */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "kexec_internal.h" atomic_t __kexec_lock = ATOMIC_INIT(0); /* Flag to indicate we are going to kexec a new kernel */ bool kexec_in_progress = false; bool kexec_file_dbg_print; /* * When kexec transitions to the new kernel there is a one-to-one * mapping between physical and virtual addresses. On processors * where you can disable the MMU this is trivial, and easy. For * others it is still a simple predictable page table to setup. * * In that environment kexec copies the new kernel to its final * resting place. This means I can only support memory whose * physical address can fit in an unsigned long. In particular * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled. * If the assembly stub has more restrictive requirements * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be * defined more restrictively in . * * The code for the transition from the current kernel to the * new kernel is placed in the control_code_buffer, whose size * is given by KEXEC_CONTROL_PAGE_SIZE. In the best case only a single * page of memory is necessary, but some architectures require more. * Because this memory must be identity mapped in the transition from * virtual to physical addresses it must live in the range * 0 - TASK_SIZE, as only the user space mappings are arbitrarily * modifiable. * * The assembly stub in the control code buffer is passed a linked list * of descriptor pages detailing the source pages of the new kernel, * and the destination addresses of those source pages. As this data * structure is not used in the context of the current OS, it must * be self-contained. * * The code has been made to work with highmem pages and will use a * destination page in its final resting place (if it happens * to allocate it). The end product of this is that most of the * physical address space, and most of RAM can be used. * * Future directions include: * - allocating a page table with the control code buffer identity * mapped, to simplify machine_kexec and make kexec_on_panic more * reliable. */ /* * KIMAGE_NO_DEST is an impossible destination address..., for * allocating pages whose destination address we do not care about. */ #define KIMAGE_NO_DEST (-1UL) #define PAGE_COUNT(x) (((x) + PAGE_SIZE - 1) >> PAGE_SHIFT) static struct page *kimage_alloc_page(struct kimage *image, gfp_t gfp_mask, unsigned long dest); int sanity_check_segment_list(struct kimage *image) { int i; unsigned long nr_segments = image->nr_segments; unsigned long total_pages = 0; unsigned long nr_pages = totalram_pages(); /* * Verify we have good destination addresses. The caller is * responsible for making certain we don't attempt to load * the new image into invalid or reserved areas of RAM. This * just verifies it is an address we can use. * * Since the kernel does everything in page size chunks ensure * the destination addresses are page aligned. Too many * special cases crop of when we don't do this. The most * insidious is getting overlapping destination addresses * simply because addresses are changed to page size * granularity. */ for (i = 0; i < nr_segments; i++) { unsigned long mstart, mend; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz; if (mstart > mend) return -EADDRNOTAVAIL; if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK)) return -EADDRNOTAVAIL; if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT) return -EADDRNOTAVAIL; } /* Verify our destination addresses do not overlap. * If we alloed overlapping destination addresses * through very weird things can happen with no * easy explanation as one segment stops on another. */ for (i = 0; i < nr_segments; i++) { unsigned long mstart, mend; unsigned long j; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz; for (j = 0; j < i; j++) { unsigned long pstart, pend; pstart = image->segment[j].mem; pend = pstart + image->segment[j].memsz; /* Do the segments overlap ? */ if ((mend > pstart) && (mstart < pend)) return -EINVAL; } } /* Ensure our buffer sizes are strictly less than * our memory sizes. This should always be the case, * and it is easier to check up front than to be surprised * later on. */ for (i = 0; i < nr_segments; i++) { if (image->segment[i].bufsz > image->segment[i].memsz) return -EINVAL; } /* * Verify that no more than half of memory will be consumed. If the * request from userspace is too large, a large amount of time will be * wasted allocating pages, which can cause a soft lockup. */ for (i = 0; i < nr_segments; i++) { if (PAGE_COUNT(image->segment[i].memsz) > nr_pages / 2) return -EINVAL; total_pages += PAGE_COUNT(image->segment[i].memsz); } if (total_pages > nr_pages / 2) return -EINVAL; #ifdef CONFIG_CRASH_DUMP /* * Verify we have good destination addresses. Normally * the caller is responsible for making certain we don't * attempt to load the new image into invalid or reserved * areas of RAM. But crash kernels are preloaded into a * reserved area of ram. We must ensure the addresses * are in the reserved area otherwise preloading the * kernel could corrupt things. */ if (image->type == KEXEC_TYPE_CRASH) { for (i = 0; i < nr_segments; i++) { unsigned long mstart, mend; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz - 1; /* Ensure we are within the crash kernel limits */ if ((mstart < phys_to_boot_phys(crashk_res.start)) || (mend > phys_to_boot_phys(crashk_res.end))) return -EADDRNOTAVAIL; } } #endif return 0; } struct kimage *do_kimage_alloc_init(void) { struct kimage *image; /* Allocate a controlling structure */ image = kzalloc(sizeof(*image), GFP_KERNEL); if (!image) return NULL; image->head = 0; image->entry = &image->head; image->last_entry = &image->head; image->control_page = ~0; /* By default this does not apply */ image->type = KEXEC_TYPE_DEFAULT; /* Initialize the list of control pages */ INIT_LIST_HEAD(&image->control_pages); /* Initialize the list of destination pages */ INIT_LIST_HEAD(&image->dest_pages); /* Initialize the list of unusable pages */ INIT_LIST_HEAD(&image->unusable_pages); #ifdef CONFIG_CRASH_HOTPLUG image->hp_action = KEXEC_CRASH_HP_NONE; image->elfcorehdr_index = -1; image->elfcorehdr_updated = false; #endif return image; } int kimage_is_destination_range(struct kimage *image, unsigned long start, unsigned long end) { unsigned long i; for (i = 0; i < image->nr_segments; i++) { unsigned long mstart, mend; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz - 1; if ((end >= mstart) && (start <= mend)) return 1; } return 0; } static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order) { struct page *pages; if (fatal_signal_pending(current)) return NULL; pages = alloc_pages(gfp_mask & ~__GFP_ZERO, order); if (pages) { unsigned int count, i; pages->mapping = NULL; set_page_private(pages, order); count = 1 << order; for (i = 0; i < count; i++) SetPageReserved(pages + i); arch_kexec_post_alloc_pages(page_address(pages), count, gfp_mask); if (gfp_mask & __GFP_ZERO) for (i = 0; i < count; i++) clear_highpage(pages + i); } return pages; } static void kimage_free_pages(struct page *page) { unsigned int order, count, i; order = page_private(page); count = 1 << order; arch_kexec_pre_free_pages(page_address(page), count); for (i = 0; i < count; i++) ClearPageReserved(page + i); __free_pages(page, order); } void kimage_free_page_list(struct list_head *list) { struct page *page, *next; list_for_each_entry_safe(page, next, list, lru) { list_del(&page->lru); kimage_free_pages(page); } } static struct page *kimage_alloc_normal_control_pages(struct kimage *image, unsigned int order) { /* Control pages are special, they are the intermediaries * that are needed while we copy the rest of the pages * to their final resting place. As such they must * not conflict with either the destination addresses * or memory the kernel is already using. * * The only case where we really need more than one of * these are for architectures where we cannot disable * the MMU and must instead generate an identity mapped * page table for all of the memory. * * At worst this runs in O(N) of the image size. */ struct list_head extra_pages; struct page *pages; unsigned int count; count = 1 << order; INIT_LIST_HEAD(&extra_pages); /* Loop while I can allocate a page and the page allocated * is a destination page. */ do { unsigned long pfn, epfn, addr, eaddr; pages = kimage_alloc_pages(KEXEC_CONTROL_MEMORY_GFP, order); if (!pages) break; pfn = page_to_boot_pfn(pages); epfn = pfn + count; addr = pfn << PAGE_SHIFT; eaddr = (epfn << PAGE_SHIFT) - 1; if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) || kimage_is_destination_range(image, addr, eaddr)) { list_add(&pages->lru, &extra_pages); pages = NULL; } } while (!pages); if (pages) { /* Remember the allocated page... */ list_add(&pages->lru, &image->control_pages); /* Because the page is already in it's destination * location we will never allocate another page at * that address. Therefore kimage_alloc_pages * will not return it (again) and we don't need * to give it an entry in image->segment[]. */ } /* Deal with the destination pages I have inadvertently allocated. * * Ideally I would convert multi-page allocations into single * page allocations, and add everything to image->dest_pages. * * For now it is simpler to just free the pages. */ kimage_free_page_list(&extra_pages); return pages; } #ifdef CONFIG_CRASH_DUMP static struct page *kimage_alloc_crash_control_pages(struct kimage *image, unsigned int order) { /* Control pages are special, they are the intermediaries * that are needed while we copy the rest of the pages * to their final resting place. As such they must * not conflict with either the destination addresses * or memory the kernel is already using. * * Control pages are also the only pags we must allocate * when loading a crash kernel. All of the other pages * are specified by the segments and we just memcpy * into them directly. * * The only case where we really need more than one of * these are for architectures where we cannot disable * the MMU and must instead generate an identity mapped * page table for all of the memory. * * Given the low demand this implements a very simple * allocator that finds the first hole of the appropriate * size in the reserved memory region, and allocates all * of the memory up to and including the hole. */ unsigned long hole_start, hole_end, size; struct page *pages; pages = NULL; size = (1 << order) << PAGE_SHIFT; hole_start = ALIGN(image->control_page, size); hole_end = hole_start + size - 1; while (hole_end <= crashk_res.end) { unsigned long i; cond_resched(); if (hole_end > KEXEC_CRASH_CONTROL_MEMORY_LIMIT) break; /* See if I overlap any of the segments */ for (i = 0; i < image->nr_segments; i++) { unsigned long mstart, mend; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz - 1; if ((hole_end >= mstart) && (hole_start <= mend)) { /* Advance the hole to the end of the segment */ hole_start = ALIGN(mend, size); hole_end = hole_start + size - 1; break; } } /* If I don't overlap any segments I have found my hole! */ if (i == image->nr_segments) { pages = pfn_to_page(hole_start >> PAGE_SHIFT); image->control_page = hole_end + 1; break; } } /* Ensure that these pages are decrypted if SME is enabled. */ if (pages) arch_kexec_post_alloc_pages(page_address(pages), 1 << order, 0); return pages; } #endif struct page *kimage_alloc_control_pages(struct kimage *image, unsigned int order) { struct page *pages = NULL; switch (image->type) { case KEXEC_TYPE_DEFAULT: pages = kimage_alloc_normal_control_pages(image, order); break; #ifdef CONFIG_CRASH_DUMP case KEXEC_TYPE_CRASH: pages = kimage_alloc_crash_control_pages(image, order); break; #endif } return pages; } static int kimage_add_entry(struct kimage *image, kimage_entry_t entry) { if (*image->entry != 0) image->entry++; if (image->entry == image->last_entry) { kimage_entry_t *ind_page; struct page *page; page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST); if (!page) return -ENOMEM; ind_page = page_address(page); *image->entry = virt_to_boot_phys(ind_page) | IND_INDIRECTION; image->entry = ind_page; image->last_entry = ind_page + ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1); } *image->entry = entry; image->entry++; *image->entry = 0; return 0; } static int kimage_set_destination(struct kimage *image, unsigned long destination) { destination &= PAGE_MASK; return kimage_add_entry(image, destination | IND_DESTINATION); } static int kimage_add_page(struct kimage *image, unsigned long page) { page &= PAGE_MASK; return kimage_add_entry(image, page | IND_SOURCE); } static void kimage_free_extra_pages(struct kimage *image) { /* Walk through and free any extra destination pages I may have */ kimage_free_page_list(&image->dest_pages); /* Walk through and free any unusable pages I have cached */ kimage_free_page_list(&image->unusable_pages); } void kimage_terminate(struct kimage *image) { if (*image->entry != 0) image->entry++; *image->entry = IND_DONE; } #define for_each_kimage_entry(image, ptr, entry) \ for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \ ptr = (entry & IND_INDIRECTION) ? \ boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1) static void kimage_free_entry(kimage_entry_t entry) { struct page *page; page = boot_pfn_to_page(entry >> PAGE_SHIFT); kimage_free_pages(page); } void kimage_free(struct kimage *image) { kimage_entry_t *ptr, entry; kimage_entry_t ind = 0; if (!image) return; #ifdef CONFIG_CRASH_DUMP if (image->vmcoreinfo_data_copy) { crash_update_vmcoreinfo_safecopy(NULL); vunmap(image->vmcoreinfo_data_copy); } #endif kimage_free_extra_pages(image); for_each_kimage_entry(image, ptr, entry) { if (entry & IND_INDIRECTION) { /* Free the previous indirection page */ if (ind & IND_INDIRECTION) kimage_free_entry(ind); /* Save this indirection page until we are * done with it. */ ind = entry; } else if (entry & IND_SOURCE) kimage_free_entry(entry); } /* Free the final indirection page */ if (ind & IND_INDIRECTION) kimage_free_entry(ind); /* Handle any machine specific cleanup */ machine_kexec_cleanup(image); /* Free the kexec control pages... */ kimage_free_page_list(&image->control_pages); /* * Free up any temporary buffers allocated. This might hit if * error occurred much later after buffer allocation. */ if (image->file_mode) kimage_file_post_load_cleanup(image); kfree(image); } static kimage_entry_t *kimage_dst_used(struct kimage *image, unsigned long page) { kimage_entry_t *ptr, entry; unsigned long destination = 0; for_each_kimage_entry(image, ptr, entry) { if (entry & IND_DESTINATION) destination = entry & PAGE_MASK; else if (entry & IND_SOURCE) { if (page == destination) return ptr; destination += PAGE_SIZE; } } return NULL; } static struct page *kimage_alloc_page(struct kimage *image, gfp_t gfp_mask, unsigned long destination) { /* * Here we implement safeguards to ensure that a source page * is not copied to its destination page before the data on * the destination page is no longer useful. * * To do this we maintain the invariant that a source page is * either its own destination page, or it is not a * destination page at all. * * That is slightly stronger than required, but the proof * that no problems will not occur is trivial, and the * implementation is simply to verify. * * When allocating all pages normally this algorithm will run * in O(N) time, but in the worst case it will run in O(N^2) * time. If the runtime is a problem the data structures can * be fixed. */ struct page *page; unsigned long addr; /* * Walk through the list of destination pages, and see if I * have a match. */ list_for_each_entry(page, &image->dest_pages, lru) { addr = page_to_boot_pfn(page) << PAGE_SHIFT; if (addr == destination) { list_del(&page->lru); return page; } } page = NULL; while (1) { kimage_entry_t *old; /* Allocate a page, if we run out of memory give up */ page = kimage_alloc_pages(gfp_mask, 0); if (!page) return NULL; /* If the page cannot be used file it away */ if (page_to_boot_pfn(page) > (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) { list_add(&page->lru, &image->unusable_pages); continue; } addr = page_to_boot_pfn(page) << PAGE_SHIFT; /* If it is the destination page we want use it */ if (addr == destination) break; /* If the page is not a destination page use it */ if (!kimage_is_destination_range(image, addr, addr + PAGE_SIZE - 1)) break; /* * I know that the page is someones destination page. * See if there is already a source page for this * destination page. And if so swap the source pages. */ old = kimage_dst_used(image, addr); if (old) { /* If so move it */ unsigned long old_addr; struct page *old_page; old_addr = *old & PAGE_MASK; old_page = boot_pfn_to_page(old_addr >> PAGE_SHIFT); copy_highpage(page, old_page); *old = addr | (*old & ~PAGE_MASK); /* The old page I have found cannot be a * destination page, so return it if it's * gfp_flags honor the ones passed in. */ if (!(gfp_mask & __GFP_HIGHMEM) && PageHighMem(old_page)) { kimage_free_pages(old_page); continue; } page = old_page; break; } /* Place the page on the destination list, to be used later */ list_add(&page->lru, &image->dest_pages); } return page; } static int kimage_load_normal_segment(struct kimage *image, struct kexec_segment *segment) { unsigned long maddr; size_t ubytes, mbytes; int result; unsigned char __user *buf = NULL; unsigned char *kbuf = NULL; if (image->file_mode) kbuf = segment->kbuf; else buf = segment->buf; ubytes = segment->bufsz; mbytes = segment->memsz; maddr = segment->mem; result = kimage_set_destination(image, maddr); if (result < 0) goto out; while (mbytes) { struct page *page; char *ptr; size_t uchunk, mchunk; page = kimage_alloc_page(image, GFP_HIGHUSER, maddr); if (!page) { result = -ENOMEM; goto out; } result = kimage_add_page(image, page_to_boot_pfn(page) << PAGE_SHIFT); if (result < 0) goto out; ptr = kmap_local_page(page); /* Start with a clear page */ clear_page(ptr); ptr += maddr & ~PAGE_MASK; mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK)); uchunk = min(ubytes, mchunk); /* For file based kexec, source pages are in kernel memory */ if (image->file_mode) memcpy(ptr, kbuf, uchunk); else result = copy_from_user(ptr, buf, uchunk); kunmap_local(ptr); if (result) { result = -EFAULT; goto out; } ubytes -= uchunk; maddr += mchunk; if (image->file_mode) kbuf += mchunk; else buf += mchunk; mbytes -= mchunk; cond_resched(); } out: return result; } #ifdef CONFIG_CRASH_DUMP static int kimage_load_crash_segment(struct kimage *image, struct kexec_segment *segment) { /* For crash dumps kernels we simply copy the data from * user space to it's destination. * We do things a page at a time for the sake of kmap. */ unsigned long maddr; size_t ubytes, mbytes; int result; unsigned char __user *buf = NULL; unsigned char *kbuf = NULL; result = 0; if (image->file_mode) kbuf = segment->kbuf; else buf = segment->buf; ubytes = segment->bufsz; mbytes = segment->memsz; maddr = segment->mem; while (mbytes) { struct page *page; char *ptr; size_t uchunk, mchunk; page = boot_pfn_to_page(maddr >> PAGE_SHIFT); if (!page) { result = -ENOMEM; goto out; } arch_kexec_post_alloc_pages(page_address(page), 1, 0); ptr = kmap_local_page(page); ptr += maddr & ~PAGE_MASK; mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK)); uchunk = min(ubytes, mchunk); if (mchunk > uchunk) { /* Zero the trailing part of the page */ memset(ptr + uchunk, 0, mchunk - uchunk); } /* For file based kexec, source pages are in kernel memory */ if (image->file_mode) memcpy(ptr, kbuf, uchunk); else result = copy_from_user(ptr, buf, uchunk); kexec_flush_icache_page(page); kunmap_local(ptr); arch_kexec_pre_free_pages(page_address(page), 1); if (result) { result = -EFAULT; goto out; } ubytes -= uchunk; maddr += mchunk; if (image->file_mode) kbuf += mchunk; else buf += mchunk; mbytes -= mchunk; cond_resched(); } out: return result; } #endif int kimage_load_segment(struct kimage *image, struct kexec_segment *segment) { int result = -ENOMEM; switch (image->type) { case KEXEC_TYPE_DEFAULT: result = kimage_load_normal_segment(image, segment); break; #ifdef CONFIG_CRASH_DUMP case KEXEC_TYPE_CRASH: result = kimage_load_crash_segment(image, segment); break; #endif } return result; } struct kexec_load_limit { /* Mutex protects the limit count. */ struct mutex mutex; int limit; }; static struct kexec_load_limit load_limit_reboot = { .mutex = __MUTEX_INITIALIZER(load_limit_reboot.mutex), .limit = -1, }; static struct kexec_load_limit load_limit_panic = { .mutex = __MUTEX_INITIALIZER(load_limit_panic.mutex), .limit = -1, }; struct kimage *kexec_image; struct kimage *kexec_crash_image; static int kexec_load_disabled; #ifdef CONFIG_SYSCTL static int kexec_limit_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { struct kexec_load_limit *limit = table->data; int val; struct ctl_table tmp = { .data = &val, .maxlen = sizeof(val), .mode = table->mode, }; int ret; if (write) { ret = proc_dointvec(&tmp, write, buffer, lenp, ppos); if (ret) return ret; if (val < 0) return -EINVAL; mutex_lock(&limit->mutex); if (limit->limit != -1 && val >= limit->limit) ret = -EINVAL; else limit->limit = val; mutex_unlock(&limit->mutex); return ret; } mutex_lock(&limit->mutex); val = limit->limit; mutex_unlock(&limit->mutex); return proc_dointvec(&tmp, write, buffer, lenp, ppos); } static struct ctl_table kexec_core_sysctls[] = { { .procname = "kexec_load_disabled", .data = &kexec_load_disabled, .maxlen = sizeof(int), .mode = 0644, /* only handle a transition from default "0" to "1" */ .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ONE, .extra2 = SYSCTL_ONE, }, { .procname = "kexec_load_limit_panic", .data = &load_limit_panic, .mode = 0644, .proc_handler = kexec_limit_handler, }, { .procname = "kexec_load_limit_reboot", .data = &load_limit_reboot, .mode = 0644, .proc_handler = kexec_limit_handler, }, { } }; static int __init kexec_core_sysctl_init(void) { register_sysctl_init("kernel", kexec_core_sysctls); return 0; } late_initcall(kexec_core_sysctl_init); #endif bool kexec_load_permitted(int kexec_image_type) { struct kexec_load_limit *limit; /* * Only the superuser can use the kexec syscall and if it has not * been disabled. */ if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return false; /* Check limit counter and decrease it.*/ limit = (kexec_image_type == KEXEC_TYPE_CRASH) ? &load_limit_panic : &load_limit_reboot; mutex_lock(&limit->mutex); if (!limit->limit) { mutex_unlock(&limit->mutex); return false; } if (limit->limit != -1) limit->limit--; mutex_unlock(&limit->mutex); return true; } /* * Move into place and start executing a preloaded standalone * executable. If nothing was preloaded return an error. */ int kernel_kexec(void) { int error = 0; if (!kexec_trylock()) return -EBUSY; if (!kexec_image) { error = -EINVAL; goto Unlock; } #ifdef CONFIG_KEXEC_JUMP if (kexec_image->preserve_context) { pm_prepare_console(); error = freeze_processes(); if (error) { error = -EBUSY; goto Restore_console; } suspend_console(); error = dpm_suspend_start(PMSG_FREEZE); if (error) goto Resume_console; /* At this point, dpm_suspend_start() has been called, * but *not* dpm_suspend_end(). We *must* call * dpm_suspend_end() now. Otherwise, drivers for * some devices (e.g. interrupt controllers) become * desynchronized with the actual state of the * hardware at resume time, and evil weirdness ensues. */ error = dpm_suspend_end(PMSG_FREEZE); if (error) goto Resume_devices; error = suspend_disable_secondary_cpus(); if (error) goto Enable_cpus; local_irq_disable(); error = syscore_suspend(); if (error) goto Enable_irqs; } else #endif { kexec_in_progress = true; kernel_restart_prepare("kexec reboot"); migrate_to_reboot_cpu(); syscore_shutdown(); /* * migrate_to_reboot_cpu() disables CPU hotplug assuming that * no further code needs to use CPU hotplug (which is true in * the reboot case). However, the kexec path depends on using * CPU hotplug again; so re-enable it here. */ cpu_hotplug_enable(); pr_notice("Starting new kernel\n"); machine_shutdown(); } kmsg_dump(KMSG_DUMP_SHUTDOWN); machine_kexec(kexec_image); #ifdef CONFIG_KEXEC_JUMP if (kexec_image->preserve_context) { syscore_resume(); Enable_irqs: local_irq_enable(); Enable_cpus: suspend_enable_secondary_cpus(); dpm_resume_start(PMSG_RESTORE); Resume_devices: dpm_resume_end(PMSG_RESTORE); Resume_console: resume_console(); thaw_processes(); Restore_console: pm_restore_console(); } #endif Unlock: kexec_unlock(); return error; }