/* * kexec.c - kexec system call * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com> * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #include <linux/mm.h> #include <linux/file.h> #include <linux/slab.h> #include <linux/fs.h> #include <linux/kexec.h> #include <linux/spinlock.h> #include <linux/list.h> #include <linux/highmem.h> #include <linux/syscalls.h> #include <linux/reboot.h> #include <linux/syscalls.h> #include <linux/ioport.h> #include <linux/hardirq.h> #include <asm/page.h> #include <asm/uaccess.h> #include <asm/io.h> #include <asm/system.h> #include <asm/semaphore.h> /* Location of the reserved area for the crash kernel */ struct resource crashk_res = { .name = "Crash kernel", .start = 0, .end = 0, .flags = IORESOURCE_BUSY | IORESOURCE_MEM }; int kexec_should_crash(struct task_struct *p) { if (in_interrupt() || !p->pid || p->pid == 1 || panic_on_oops) return 1; return 0; } /* * 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 <asm/kexec.h>. * * The code for the transition from the current kernel to the * the new kernel is placed in the control_code_buffer, whose size * is given by KEXEC_CONTROL_CODE_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) static int kimage_is_destination_range(struct kimage *image, unsigned long start, unsigned long end); static struct page *kimage_alloc_page(struct kimage *image, unsigned int gfp_mask, unsigned long dest); static int do_kimage_alloc(struct kimage **rimage, unsigned long entry, unsigned long nr_segments, struct kexec_segment __user *segments) { size_t segment_bytes; struct kimage *image; unsigned long i; int result; /* Allocate a controlling structure */ result = -ENOMEM; image = kmalloc(sizeof(*image), GFP_KERNEL); if (!image) goto out; memset(image, 0, sizeof(*image)); image->head = 0; image->entry = &image->head; image->last_entry = &image->head; image->control_page = ~0; /* By default this does not apply */ image->start = entry; 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 unuseable pages */ INIT_LIST_HEAD(&image->unuseable_pages); /* Read in the segments */ image->nr_segments = nr_segments; segment_bytes = nr_segments * sizeof(*segments); result = copy_from_user(image->segment, segments, segment_bytes); if (result) goto out; /* * 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 addreses 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. */ result = -EADDRNOTAVAIL; for (i = 0; i < nr_segments; i++) { unsigned long mstart, mend; mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz; if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK)) goto out; if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT) goto out; } /* 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. */ result = -EINVAL; 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)) goto out; } } /* 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. */ result = -EINVAL; for (i = 0; i < nr_segments; i++) { if (image->segment[i].bufsz > image->segment[i].memsz) goto out; } result = 0; out: if (result == 0) *rimage = image; else kfree(image); return result; } static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry, unsigned long nr_segments, struct kexec_segment __user *segments) { int result; struct kimage *image; /* Allocate and initialize a controlling structure */ image = NULL; result = do_kimage_alloc(&image, entry, nr_segments, segments); if (result) goto out; *rimage = image; /* * Find a location for the control code buffer, and add it * the vector of segments so that it's pages will also be * counted as destination pages. */ result = -ENOMEM; image->control_code_page = kimage_alloc_control_pages(image, get_order(KEXEC_CONTROL_CODE_SIZE)); if (!image->control_code_page) { printk(KERN_ERR "Could not allocate control_code_buffer\n"); goto out; } result = 0; out: if (result == 0) *rimage = image; else kfree(image); return result; } static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry, unsigned long nr_segments, struct kexec_segment __user *segments) { int result; struct kimage *image; unsigned long i; image = NULL; /* Verify we have a valid entry point */ if ((entry < crashk_res.start) || (entry > crashk_res.end)) { result = -EADDRNOTAVAIL; goto out; } /* Allocate and initialize a controlling structure */ result = do_kimage_alloc(&image, entry, nr_segments, segments); if (result) goto out; /* Enable the special crash kernel control page * allocation policy. */ image->control_page = crashk_res.start; image->type = KEXEC_TYPE_CRASH; /* * 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. */ result = -EADDRNOTAVAIL; 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 < crashk_res.start) || (mend > crashk_res.end)) goto out; } /* * Find a location for the control code buffer, and add * the vector of segments so that it's pages will also be * counted as destination pages. */ result = -ENOMEM; image->control_code_page = kimage_alloc_control_pages(image, get_order(KEXEC_CONTROL_CODE_SIZE)); if (!image->control_code_page) { printk(KERN_ERR "Could not allocate control_code_buffer\n"); goto out; } result = 0; out: if (result == 0) *rimage = image; else kfree(image); return result; } static 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; if ((end > mstart) && (start < mend)) return 1; } return 0; } static struct page *kimage_alloc_pages(unsigned int gfp_mask, unsigned int order) { struct page *pages; pages = alloc_pages(gfp_mask, order); if (pages) { unsigned int count, i; pages->mapping = NULL; pages->private = order; count = 1 << order; for (i = 0; i < count; i++) SetPageReserved(pages + i); } return pages; } static void kimage_free_pages(struct page *page) { unsigned int order, count, i; order = page->private; count = 1 << order; for (i = 0; i < count; i++) ClearPageReserved(page + i); __free_pages(page, order); } static void kimage_free_page_list(struct list_head *list) { struct list_head *pos, *next; list_for_each_safe(pos, next, list) { struct page *page; page = list_entry(pos, struct page, 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(GFP_KERNEL, order); if (!pages) break; pfn = page_to_pfn(pages); epfn = pfn + count; addr = pfn << PAGE_SHIFT; eaddr = epfn << PAGE_SHIFT; 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 everyting to image->dest_pages. * * For now it is simpler to just free the pages. */ kimage_free_page_list(&extra_pages); return pages; } 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 = (image->control_page + (size - 1)) & ~(size - 1); hole_end = hole_start + size - 1; while (hole_end <= crashk_res.end) { unsigned long i; if (hole_end > KEXEC_CONTROL_MEMORY_LIMIT) break; if (hole_end > crashk_res.end) 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 = (mend + (size - 1)) & ~(size - 1); 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); break; } } if (pages) image->control_page = hole_end; return pages; } 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; case KEXEC_TYPE_CRASH: pages = kimage_alloc_crash_control_pages(image, order); break; } 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_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) { int result; destination &= PAGE_MASK; result = kimage_add_entry(image, destination | IND_DESTINATION); if (result == 0) image->destination = destination; return result; } static int kimage_add_page(struct kimage *image, unsigned long page) { int result; page &= PAGE_MASK; result = kimage_add_entry(image, page | IND_SOURCE); if (result == 0) image->destination += PAGE_SIZE; return result; } 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 unuseable pages I have cached */ kimage_free_page_list(&image->unuseable_pages); } static int kimage_terminate(struct kimage *image) { if (*image->entry != 0) image->entry++; *image->entry = IND_DONE; return 0; } #define for_each_kimage_entry(image, ptr, entry) \ for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \ ptr = (entry & IND_INDIRECTION)? \ phys_to_virt((entry & PAGE_MASK)): ptr +1) static void kimage_free_entry(kimage_entry_t entry) { struct page *page; page = pfn_to_page(entry >> PAGE_SHIFT); kimage_free_pages(page); } static void kimage_free(struct kimage *image) { kimage_entry_t *ptr, entry; kimage_entry_t ind = 0; if (!image) return; 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); 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, unsigned int 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_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_pfn(page) > (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) { list_add(&page->lru, &image->unuseable_pages); continue; } addr = page_to_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)) 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 = 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. */ addr = old_addr; page = old_page; break; } else { /* Place the page on the destination list I * will use it 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; unsigned long ubytes, mbytes; int result; unsigned char __user *buf; result = 0; 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 == 0) { result = -ENOMEM; goto out; } result = kimage_add_page(image, page_to_pfn(page) << PAGE_SHIFT); if (result < 0) goto out; ptr = kmap(page); /* Start with a clear page */ memset(ptr, 0, PAGE_SIZE); ptr += maddr & ~PAGE_MASK; mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); if (mchunk > mbytes) mchunk = mbytes; uchunk = mchunk; if (uchunk > ubytes) uchunk = ubytes; result = copy_from_user(ptr, buf, uchunk); kunmap(page); if (result) { result = (result < 0) ? result : -EIO; goto out; } ubytes -= uchunk; maddr += mchunk; buf += mchunk; mbytes -= mchunk; } out: return result; } 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; unsigned long ubytes, mbytes; int result; unsigned char __user *buf; result = 0; buf = segment->buf; ubytes = segment->bufsz; mbytes = segment->memsz; maddr = segment->mem; while (mbytes) { struct page *page; char *ptr; size_t uchunk, mchunk; page = pfn_to_page(maddr >> PAGE_SHIFT); if (page == 0) { result = -ENOMEM; goto out; } ptr = kmap(page); ptr += maddr & ~PAGE_MASK; mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); if (mchunk > mbytes) mchunk = mbytes; uchunk = mchunk; if (uchunk > ubytes) { uchunk = ubytes; /* Zero the trailing part of the page */ memset(ptr + uchunk, 0, mchunk - uchunk); } result = copy_from_user(ptr, buf, uchunk); kunmap(page); if (result) { result = (result < 0) ? result : -EIO; goto out; } ubytes -= uchunk; maddr += mchunk; buf += mchunk; mbytes -= mchunk; } out: return result; } static 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; case KEXEC_TYPE_CRASH: result = kimage_load_crash_segment(image, segment); break; } return result; } /* * Exec Kernel system call: for obvious reasons only root may call it. * * This call breaks up into three pieces. * - A generic part which loads the new kernel from the current * address space, and very carefully places the data in the * allocated pages. * * - A generic part that interacts with the kernel and tells all of * the devices to shut down. Preventing on-going dmas, and placing * the devices in a consistent state so a later kernel can * reinitialize them. * * - A machine specific part that includes the syscall number * and the copies the image to it's final destination. And * jumps into the image at entry. * * kexec does not sync, or unmount filesystems so if you need * that to happen you need to do that yourself. */ struct kimage *kexec_image = NULL; static struct kimage *kexec_crash_image = NULL; /* * A home grown binary mutex. * Nothing can wait so this mutex is safe to use * in interrupt context :) */ static int kexec_lock = 0; asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments, struct kexec_segment __user *segments, unsigned long flags) { struct kimage **dest_image, *image; int locked; int result; /* We only trust the superuser with rebooting the system. */ if (!capable(CAP_SYS_BOOT)) return -EPERM; /* * Verify we have a legal set of flags * This leaves us room for future extensions. */ if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK)) return -EINVAL; /* Verify we are on the appropriate architecture */ if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) && ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT)) return -EINVAL; /* Put an artificial cap on the number * of segments passed to kexec_load. */ if (nr_segments > KEXEC_SEGMENT_MAX) return -EINVAL; image = NULL; result = 0; /* Because we write directly to the reserved memory * region when loading crash kernels we need a mutex here to * prevent multiple crash kernels from attempting to load * simultaneously, and to prevent a crash kernel from loading * over the top of a in use crash kernel. * * KISS: always take the mutex. */ locked = xchg(&kexec_lock, 1); if (locked) return -EBUSY; dest_image = &kexec_image; if (flags & KEXEC_ON_CRASH) dest_image = &kexec_crash_image; if (nr_segments > 0) { unsigned long i; /* Loading another kernel to reboot into */ if ((flags & KEXEC_ON_CRASH) == 0) result = kimage_normal_alloc(&image, entry, nr_segments, segments); /* Loading another kernel to switch to if this one crashes */ else if (flags & KEXEC_ON_CRASH) { /* Free any current crash dump kernel before * we corrupt it. */ kimage_free(xchg(&kexec_crash_image, NULL)); result = kimage_crash_alloc(&image, entry, nr_segments, segments); } if (result) goto out; result = machine_kexec_prepare(image); if (result) goto out; for (i = 0; i < nr_segments; i++) { result = kimage_load_segment(image, &image->segment[i]); if (result) goto out; } result = kimage_terminate(image); if (result) goto out; } /* Install the new kernel, and Uninstall the old */ image = xchg(dest_image, image); out: xchg(&kexec_lock, 0); /* Release the mutex */ kimage_free(image); return result; } #ifdef CONFIG_COMPAT asmlinkage long compat_sys_kexec_load(unsigned long entry, unsigned long nr_segments, struct compat_kexec_segment __user *segments, unsigned long flags) { struct compat_kexec_segment in; struct kexec_segment out, __user *ksegments; unsigned long i, result; /* Don't allow clients that don't understand the native * architecture to do anything. */ if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT) return -EINVAL; if (nr_segments > KEXEC_SEGMENT_MAX) return -EINVAL; ksegments = compat_alloc_user_space(nr_segments * sizeof(out)); for (i=0; i < nr_segments; i++) { result = copy_from_user(&in, &segments[i], sizeof(in)); if (result) return -EFAULT; out.buf = compat_ptr(in.buf); out.bufsz = in.bufsz; out.mem = in.mem; out.memsz = in.memsz; result = copy_to_user(&ksegments[i], &out, sizeof(out)); if (result) return -EFAULT; } return sys_kexec_load(entry, nr_segments, ksegments, flags); } #endif void crash_kexec(struct pt_regs *regs) { struct kimage *image; int locked; /* 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... */ locked = xchg(&kexec_lock, 1); if (!locked) { image = xchg(&kexec_crash_image, NULL); if (image) { machine_crash_shutdown(regs); machine_kexec(image); } xchg(&kexec_lock, 0); } }