kexec.c 35.4 KB
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/*
 * 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.
 */

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#include <linux/capability.h>
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#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/ioport.h>
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#include <linux/hardirq.h>
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#include <linux/elf.h>
#include <linux/elfcore.h>
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#include <linux/utsrelease.h>
#include <linux/utsname.h>
#include <linux/numa.h>
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#include <asm/page.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/system.h>
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#include <asm/sections.h>
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/* Per cpu memory for storing cpu states in case of system crash. */
note_buf_t* crash_notes;

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/* vmcoreinfo stuff */
unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
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size_t vmcoreinfo_size;
size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
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/* 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
};

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int kexec_should_crash(struct task_struct *p)
{
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	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
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		return 1;
	return 0;
}

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/*
 * 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)

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static int kimage_is_destination_range(struct kimage *image,
				       unsigned long start, unsigned long end);
static struct page *kimage_alloc_page(struct kimage *image,
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				       gfp_t gfp_mask,
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				       unsigned long dest);
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static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
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	                    unsigned long nr_segments,
                            struct kexec_segment __user *segments)
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{
	size_t segment_bytes;
	struct kimage *image;
	unsigned long i;
	int result;

	/* Allocate a controlling structure */
	result = -ENOMEM;
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	image = kzalloc(sizeof(*image), GFP_KERNEL);
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	if (!image)
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		goto out;
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	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;
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		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;
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	for (i = 0; i < nr_segments; i++) {
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		unsigned long mstart, mend;
		unsigned long j;
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		mstart = image->segment[i].mem;
		mend   = mstart + image->segment[i].memsz;
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		for (j = 0; j < i; j++) {
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			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;
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	for (i = 0; i < nr_segments; i++) {
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		if (image->segment[i].bufsz > image->segment[i].memsz)
			goto out;
	}

	result = 0;
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out:
	if (result == 0)
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		*rimage = image;
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	else
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		kfree(image);
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	return result;

}

static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
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				unsigned long nr_segments,
				struct kexec_segment __user *segments)
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{
	int result;
	struct kimage *image;

	/* Allocate and initialize a controlling structure */
	image = NULL;
	result = do_kimage_alloc(&image, entry, nr_segments, segments);
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	if (result)
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		goto out;
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	*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,
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					   get_order(KEXEC_CONTROL_CODE_SIZE));
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	if (!image->control_code_page) {
		printk(KERN_ERR "Could not allocate control_code_buffer\n");
		goto out;
	}

	result = 0;
 out:
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	if (result == 0)
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		*rimage = image;
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	else
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		kfree(image);
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	return result;
}

static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
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				unsigned long nr_segments,
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				struct kexec_segment __user *segments)
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{
	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);
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	if (result)
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		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;
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		mstart = image->segment[i].mem;
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		mend = mstart + image->segment[i].memsz - 1;
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		/* 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,
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					   get_order(KEXEC_CONTROL_CODE_SIZE));
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	if (!image->control_code_page) {
		printk(KERN_ERR "Could not allocate control_code_buffer\n");
		goto out;
	}

	result = 0;
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out:
	if (result == 0)
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		*rimage = image;
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	else
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		kfree(image);
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	return result;
}

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static int kimage_is_destination_range(struct kimage *image,
					unsigned long start,
					unsigned long end)
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{
	unsigned long i;

	for (i = 0; i < image->nr_segments; i++) {
		unsigned long mstart, mend;
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		mstart = image->segment[i].mem;
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		mend = mstart + image->segment[i].memsz;
		if ((end > mstart) && (start < mend))
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			return 1;
	}
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	return 0;
}

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static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
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{
	struct page *pages;
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	pages = alloc_pages(gfp_mask, order);
	if (pages) {
		unsigned int count, i;
		pages->mapping = NULL;
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		set_page_private(pages, order);
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		count = 1 << order;
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		for (i = 0; i < count; i++)
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			SetPageReserved(pages + i);
	}
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	return pages;
}

static void kimage_free_pages(struct page *page)
{
	unsigned int order, count, i;
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	order = page_private(page);
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	count = 1 << order;
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	for (i = 0; i < count; i++)
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		ClearPageReserved(page + i);
	__free_pages(page, order);
}

static void kimage_free_page_list(struct list_head *list)
{
	struct list_head *pos, *next;
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	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);
	}
}

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static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
							unsigned int order)
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{
	/* 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;
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		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)) ||
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			      kimage_is_destination_range(image, addr, eaddr)) {
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			list_add(&pages->lru, &extra_pages);
			pages = NULL;
		}
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	} while (!pages);

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	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);

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	return pages;
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}

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static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
						      unsigned int order)
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{
	/* 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;
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	pages = NULL;
	size = (1 << order) << PAGE_SHIFT;
	hole_start = (image->control_page + (size - 1)) & ~(size - 1);
	hole_end   = hole_start + size - 1;
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	while (hole_end <= crashk_res.end) {
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		unsigned long i;
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		if (hole_end > KEXEC_CONTROL_MEMORY_LIMIT)
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			break;
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		if (hole_end > crashk_res.end)
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			break;
		/* See if I overlap any of the segments */
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		for (i = 0; i < image->nr_segments; i++) {
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			unsigned long mstart, mend;
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			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;
		}
	}
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	if (pages)
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		image->control_page = hole_end;
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	return pages;
}


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struct page *kimage_alloc_control_pages(struct kimage *image,
					 unsigned int order)
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{
	struct page *pages = NULL;
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	switch (image->type) {
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	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;
	}
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	return pages;
}

static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
{
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	if (*image->entry != 0)
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		image->entry++;
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	if (image->entry == image->last_entry) {
		kimage_entry_t *ind_page;
		struct page *page;
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		page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);
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		if (!page)
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			return -ENOMEM;
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		ind_page = page_address(page);
		*image->entry = virt_to_phys(ind_page) | IND_INDIRECTION;
		image->entry = ind_page;
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		image->last_entry = ind_page +
				      ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);
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	}
	*image->entry = entry;
	image->entry++;
	*image->entry = 0;
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	return 0;
}

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static int kimage_set_destination(struct kimage *image,
				   unsigned long destination)
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{
	int result;

	destination &= PAGE_MASK;
	result = kimage_add_entry(image, destination | IND_DESTINATION);
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	if (result == 0)
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		image->destination = destination;
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	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);
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	if (result == 0)
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		image->destination += PAGE_SIZE;
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	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)
{
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	if (*image->entry != 0)
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		image->entry++;
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	*image->entry = IND_DONE;
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	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;
M
Maneesh Soni 已提交
622

623 624 625 626
	kimage_free_extra_pages(image);
	for_each_kimage_entry(image, ptr, entry) {
		if (entry & IND_INDIRECTION) {
			/* Free the previous indirection page */
M
Maneesh Soni 已提交
627
			if (ind & IND_INDIRECTION)
628 629 630 631 632 633
				kimage_free_entry(ind);
			/* Save this indirection page until we are
			 * done with it.
			 */
			ind = entry;
		}
M
Maneesh Soni 已提交
634
		else if (entry & IND_SOURCE)
635 636 637
			kimage_free_entry(entry);
	}
	/* Free the final indirection page */
M
Maneesh Soni 已提交
638
	if (ind & IND_INDIRECTION)
639 640 641 642 643 644 645 646 647 648
		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);
}

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Maneesh Soni 已提交
649 650
static kimage_entry_t *kimage_dst_used(struct kimage *image,
					unsigned long page)
651 652 653 654 655
{
	kimage_entry_t *ptr, entry;
	unsigned long destination = 0;

	for_each_kimage_entry(image, ptr, entry) {
M
Maneesh Soni 已提交
656
		if (entry & IND_DESTINATION)
657 658
			destination = entry & PAGE_MASK;
		else if (entry & IND_SOURCE) {
M
Maneesh Soni 已提交
659
			if (page == destination)
660 661 662 663
				return ptr;
			destination += PAGE_SIZE;
		}
	}
M
Maneesh Soni 已提交
664

665
	return NULL;
666 667
}

M
Maneesh Soni 已提交
668
static struct page *kimage_alloc_page(struct kimage *image,
A
Al Viro 已提交
669
					gfp_t gfp_mask,
M
Maneesh Soni 已提交
670
					unsigned long destination)
671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709
{
	/*
	 * 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);
M
Maneesh Soni 已提交
710
		if (!page)
711
			return NULL;
712
		/* If the page cannot be used file it away */
M
Maneesh Soni 已提交
713 714
		if (page_to_pfn(page) >
				(KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {
715 716 717 718 719 720 721 722 723 724
			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 */
M
Maneesh Soni 已提交
725 726
		if (!kimage_is_destination_range(image, addr,
						  addr + PAGE_SIZE))
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758
			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);
		}
	}
M
Maneesh Soni 已提交
759

760 761 762 763
	return page;
}

static int kimage_load_normal_segment(struct kimage *image,
M
Maneesh Soni 已提交
764
					 struct kexec_segment *segment)
765 766 767 768
{
	unsigned long maddr;
	unsigned long ubytes, mbytes;
	int result;
769
	unsigned char __user *buf;
770 771 772 773 774 775 776 777

	result = 0;
	buf = segment->buf;
	ubytes = segment->bufsz;
	mbytes = segment->memsz;
	maddr = segment->mem;

	result = kimage_set_destination(image, maddr);
M
Maneesh Soni 已提交
778
	if (result < 0)
779
		goto out;
M
Maneesh Soni 已提交
780 781

	while (mbytes) {
782 783 784
		struct page *page;
		char *ptr;
		size_t uchunk, mchunk;
M
Maneesh Soni 已提交
785

786
		page = kimage_alloc_page(image, GFP_HIGHUSER, maddr);
787
		if (!page) {
788 789 790
			result  = -ENOMEM;
			goto out;
		}
M
Maneesh Soni 已提交
791 792 793
		result = kimage_add_page(image, page_to_pfn(page)
								<< PAGE_SHIFT);
		if (result < 0)
794
			goto out;
M
Maneesh Soni 已提交
795

796 797 798 799 800
		ptr = kmap(page);
		/* Start with a clear page */
		memset(ptr, 0, PAGE_SIZE);
		ptr += maddr & ~PAGE_MASK;
		mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
M
Maneesh Soni 已提交
801
		if (mchunk > mbytes)
802
			mchunk = mbytes;
M
Maneesh Soni 已提交
803

804
		uchunk = mchunk;
M
Maneesh Soni 已提交
805
		if (uchunk > ubytes)
806
			uchunk = ubytes;
M
Maneesh Soni 已提交
807

808 809 810 811 812 813 814 815 816 817 818
		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;
	}
M
Maneesh Soni 已提交
819
out:
820 821 822 823
	return result;
}

static int kimage_load_crash_segment(struct kimage *image,
M
Maneesh Soni 已提交
824
					struct kexec_segment *segment)
825 826 827 828 829 830 831 832
{
	/* 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;
833
	unsigned char __user *buf;
834 835 836 837 838 839

	result = 0;
	buf = segment->buf;
	ubytes = segment->bufsz;
	mbytes = segment->memsz;
	maddr = segment->mem;
M
Maneesh Soni 已提交
840
	while (mbytes) {
841 842 843
		struct page *page;
		char *ptr;
		size_t uchunk, mchunk;
M
Maneesh Soni 已提交
844

845
		page = pfn_to_page(maddr >> PAGE_SHIFT);
846
		if (!page) {
847 848 849 850 851 852
			result  = -ENOMEM;
			goto out;
		}
		ptr = kmap(page);
		ptr += maddr & ~PAGE_MASK;
		mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
M
Maneesh Soni 已提交
853
		if (mchunk > mbytes)
854
			mchunk = mbytes;
M
Maneesh Soni 已提交
855

856 857 858 859 860 861 862
		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);
Z
Zou Nan hai 已提交
863
		kexec_flush_icache_page(page);
864 865 866 867 868 869 870 871 872 873
		kunmap(page);
		if (result) {
			result = (result < 0) ? result : -EIO;
			goto out;
		}
		ubytes -= uchunk;
		maddr  += mchunk;
		buf    += mchunk;
		mbytes -= mchunk;
	}
M
Maneesh Soni 已提交
874
out:
875 876 877 878
	return result;
}

static int kimage_load_segment(struct kimage *image,
M
Maneesh Soni 已提交
879
				struct kexec_segment *segment)
880 881
{
	int result = -ENOMEM;
M
Maneesh Soni 已提交
882 883

	switch (image->type) {
884 885 886 887 888 889 890
	case KEXEC_TYPE_DEFAULT:
		result = kimage_load_normal_segment(image, segment);
		break;
	case KEXEC_TYPE_CRASH:
		result = kimage_load_crash_segment(image, segment);
		break;
	}
M
Maneesh Soni 已提交
891

892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914
	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.
 */
915 916
struct kimage *kexec_image;
struct kimage *kexec_crash_image;
917 918 919 920 921
/*
 * A home grown binary mutex.
 * Nothing can wait so this mutex is safe to use
 * in interrupt context :)
 */
922
static int kexec_lock;
923

M
Maneesh Soni 已提交
924 925 926
asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
				struct kexec_segment __user *segments,
				unsigned long flags)
927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965
{
	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);
M
Maneesh Soni 已提交
966
	if (locked)
967
		return -EBUSY;
M
Maneesh Soni 已提交
968

969
	dest_image = &kexec_image;
M
Maneesh Soni 已提交
970
	if (flags & KEXEC_ON_CRASH)
971 972 973
		dest_image = &kexec_crash_image;
	if (nr_segments > 0) {
		unsigned long i;
M
Maneesh Soni 已提交
974

975
		/* Loading another kernel to reboot into */
M
Maneesh Soni 已提交
976 977 978
		if ((flags & KEXEC_ON_CRASH) == 0)
			result = kimage_normal_alloc(&image, entry,
							nr_segments, segments);
979 980 981 982 983 984
		/* 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));
M
Maneesh Soni 已提交
985 986
			result = kimage_crash_alloc(&image, entry,
						     nr_segments, segments);
987
		}
M
Maneesh Soni 已提交
988
		if (result)
989
			goto out;
M
Maneesh Soni 已提交
990

991
		result = machine_kexec_prepare(image);
M
Maneesh Soni 已提交
992
		if (result)
993
			goto out;
M
Maneesh Soni 已提交
994 995

		for (i = 0; i < nr_segments; i++) {
996
			result = kimage_load_segment(image, &image->segment[i]);
M
Maneesh Soni 已提交
997
			if (result)
998 999 1000
				goto out;
		}
		result = kimage_terminate(image);
M
Maneesh Soni 已提交
1001
		if (result)
1002 1003 1004 1005 1006
			goto out;
	}
	/* Install the new kernel, and  Uninstall the old */
	image = xchg(dest_image, image);

M
Maneesh Soni 已提交
1007
out:
R
Roland McGrath 已提交
1008 1009
	locked = xchg(&kexec_lock, 0); /* Release the mutex */
	BUG_ON(!locked);
1010
	kimage_free(image);
M
Maneesh Soni 已提交
1011

1012 1013 1014 1015 1016
	return result;
}

#ifdef CONFIG_COMPAT
asmlinkage long compat_sys_kexec_load(unsigned long entry,
M
Maneesh Soni 已提交
1017 1018 1019
				unsigned long nr_segments,
				struct compat_kexec_segment __user *segments,
				unsigned long flags)
1020 1021 1022 1023 1024 1025 1026 1027
{
	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.
	 */
M
Maneesh Soni 已提交
1028
	if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
1029 1030
		return -EINVAL;

M
Maneesh Soni 已提交
1031
	if (nr_segments > KEXEC_SEGMENT_MAX)
1032 1033 1034 1035 1036
		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));
M
Maneesh Soni 已提交
1037
		if (result)
1038 1039 1040 1041 1042 1043 1044 1045
			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));
M
Maneesh Soni 已提交
1046
		if (result)
1047 1048 1049 1050 1051 1052 1053
			return -EFAULT;
	}

	return sys_kexec_load(entry, nr_segments, ksegments, flags);
}
#endif

1054
void crash_kexec(struct pt_regs *regs)
1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
{
	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) {
1069
		if (kexec_crash_image) {
1070 1071
			struct pt_regs fixed_regs;
			crash_setup_regs(&fixed_regs, regs);
K
Ken'ichi Ohmichi 已提交
1072
			crash_save_vmcoreinfo();
1073
			machine_crash_shutdown(&fixed_regs);
1074
			machine_kexec(kexec_crash_image);
1075
		}
R
Roland McGrath 已提交
1076 1077
		locked = xchg(&kexec_lock, 0);
		BUG_ON(!locked);
1078 1079
	}
}
1080

1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
			    size_t data_len)
{
	struct elf_note note;

	note.n_namesz = strlen(name) + 1;
	note.n_descsz = data_len;
	note.n_type   = type;
	memcpy(buf, &note, sizeof(note));
	buf += (sizeof(note) + 3)/4;
	memcpy(buf, name, note.n_namesz);
	buf += (note.n_namesz + 3)/4;
	memcpy(buf, data, note.n_descsz);
	buf += (note.n_descsz + 3)/4;

	return buf;
}

static void final_note(u32 *buf)
{
	struct elf_note note;

	note.n_namesz = 0;
	note.n_descsz = 0;
	note.n_type   = 0;
	memcpy(buf, &note, sizeof(note));
}

void crash_save_cpu(struct pt_regs *regs, int cpu)
{
	struct elf_prstatus prstatus;
	u32 *buf;

	if ((cpu < 0) || (cpu >= NR_CPUS))
		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.pr_pid = current->pid;
	elf_core_copy_regs(&prstatus.pr_reg, regs);
1130 1131
	buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
		      	      &prstatus, sizeof(prstatus));
1132 1133 1134
	final_note(buf);
}

1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
static int __init crash_notes_memory_init(void)
{
	/* Allocate memory for saving cpu registers. */
	crash_notes = alloc_percpu(note_buf_t);
	if (!crash_notes) {
		printk("Kexec: Memory allocation for saving cpu register"
		" states failed\n");
		return -ENOMEM;
	}
	return 0;
}
module_init(crash_notes_memory_init)
K
Ken'ichi Ohmichi 已提交
1147

B
Bernhard Walle 已提交
1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219

/*
 * parsing the "crashkernel" commandline
 *
 * this code is intended to be called from architecture specific code
 */


/*
 * This function parses command lines in the format
 *
 *   crashkernel=ramsize-range:size[,...][@offset]
 *
 * The function returns 0 on success and -EINVAL on failure.
 */
static int __init parse_crashkernel_mem(char 			*cmdline,
					unsigned long long	system_ram,
					unsigned long long	*crash_size,
					unsigned long long	*crash_base)
{
	char *cur = cmdline, *tmp;

	/* for each entry of the comma-separated list */
	do {
		unsigned long long start, end = ULLONG_MAX, size;

		/* get the start of the range */
		start = memparse(cur, &tmp);
		if (cur == tmp) {
			pr_warning("crashkernel: Memory value expected\n");
			return -EINVAL;
		}
		cur = tmp;
		if (*cur != '-') {
			pr_warning("crashkernel: '-' expected\n");
			return -EINVAL;
		}
		cur++;

		/* if no ':' is here, than we read the end */
		if (*cur != ':') {
			end = memparse(cur, &tmp);
			if (cur == tmp) {
				pr_warning("crashkernel: Memory "
						"value expected\n");
				return -EINVAL;
			}
			cur = tmp;
			if (end <= start) {
				pr_warning("crashkernel: end <= start\n");
				return -EINVAL;
			}
		}

		if (*cur != ':') {
			pr_warning("crashkernel: ':' expected\n");
			return -EINVAL;
		}
		cur++;

		size = memparse(cur, &tmp);
		if (cur == tmp) {
			pr_warning("Memory value expected\n");
			return -EINVAL;
		}
		cur = tmp;
		if (size >= system_ram) {
			pr_warning("crashkernel: invalid size\n");
			return -EINVAL;
		}

		/* match ? */
1220
		if (system_ram >= start && system_ram < end) {
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			*crash_size = size;
			break;
		}
	} while (*cur++ == ',');

	if (*crash_size > 0) {
		while (*cur != ' ' && *cur != '@')
			cur++;
		if (*cur == '@') {
			cur++;
			*crash_base = memparse(cur, &tmp);
			if (cur == tmp) {
				pr_warning("Memory value expected "
						"after '@'\n");
				return -EINVAL;
			}
		}
	}

	return 0;
}

/*
 * That function parses "simple" (old) crashkernel command lines like
 *
 * 	crashkernel=size[@offset]
 *
 * It returns 0 on success and -EINVAL on failure.
 */
static int __init parse_crashkernel_simple(char 		*cmdline,
					   unsigned long long 	*crash_size,
					   unsigned long long 	*crash_base)
{
	char *cur = cmdline;

	*crash_size = memparse(cmdline, &cur);
	if (cmdline == cur) {
		pr_warning("crashkernel: memory value expected\n");
		return -EINVAL;
	}

	if (*cur == '@')
		*crash_base = memparse(cur+1, &cur);

	return 0;
}

/*
 * That function is the entry point for command line parsing and should be
 * called from the arch-specific code.
 */
int __init parse_crashkernel(char 		 *cmdline,
			     unsigned long long system_ram,
			     unsigned long long *crash_size,
			     unsigned long long *crash_base)
{
	char 	*p = cmdline, *ck_cmdline = NULL;
	char	*first_colon, *first_space;

	BUG_ON(!crash_size || !crash_base);
	*crash_size = 0;
	*crash_base = 0;

	/* find crashkernel and use the last one if there are more */
	p = strstr(p, "crashkernel=");
	while (p) {
		ck_cmdline = p;
		p = strstr(p+1, "crashkernel=");
	}

	if (!ck_cmdline)
		return -EINVAL;

	ck_cmdline += 12; /* strlen("crashkernel=") */

	/*
	 * if the commandline contains a ':', then that's the extended
	 * syntax -- if not, it must be the classic syntax
	 */
	first_colon = strchr(ck_cmdline, ':');
	first_space = strchr(ck_cmdline, ' ');
	if (first_colon && (!first_space || first_colon < first_space))
		return parse_crashkernel_mem(ck_cmdline, system_ram,
				crash_size, crash_base);
	else
		return parse_crashkernel_simple(ck_cmdline, crash_size,
				crash_base);

	return 0;
}



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void crash_save_vmcoreinfo(void)
{
	u32 *buf;

	if (!vmcoreinfo_size)
		return;

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	vmcoreinfo_append_str("CRASHTIME=%ld", get_seconds());
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	buf = (u32 *)vmcoreinfo_note;

	buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
			      vmcoreinfo_size);

	final_note(buf);
}

void vmcoreinfo_append_str(const char *fmt, ...)
{
	va_list args;
	char buf[0x50];
	int r;

	va_start(args, fmt);
	r = vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);

	if (r + vmcoreinfo_size > vmcoreinfo_max_size)
		r = vmcoreinfo_max_size - vmcoreinfo_size;

	memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);

	vmcoreinfo_size += r;
}

/*
 * provide an empty default implementation here -- architecture
 * code may override this
 */
void __attribute__ ((weak)) arch_crash_save_vmcoreinfo(void)
{}

unsigned long __attribute__ ((weak)) paddr_vmcoreinfo_note(void)
{
	return __pa((unsigned long)(char *)&vmcoreinfo_note);
}

static int __init crash_save_vmcoreinfo_init(void)
{
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	VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
	VMCOREINFO_PAGESIZE(PAGE_SIZE);
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	VMCOREINFO_SYMBOL(init_uts_ns);
	VMCOREINFO_SYMBOL(node_online_map);
	VMCOREINFO_SYMBOL(swapper_pg_dir);
	VMCOREINFO_SYMBOL(_stext);
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#ifndef CONFIG_NEED_MULTIPLE_NODES
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	VMCOREINFO_SYMBOL(mem_map);
	VMCOREINFO_SYMBOL(contig_page_data);
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#endif
#ifdef CONFIG_SPARSEMEM
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	VMCOREINFO_SYMBOL(mem_section);
	VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
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	VMCOREINFO_STRUCT_SIZE(mem_section);
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	VMCOREINFO_OFFSET(mem_section, section_mem_map);
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#endif
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	VMCOREINFO_STRUCT_SIZE(page);
	VMCOREINFO_STRUCT_SIZE(pglist_data);
	VMCOREINFO_STRUCT_SIZE(zone);
	VMCOREINFO_STRUCT_SIZE(free_area);
	VMCOREINFO_STRUCT_SIZE(list_head);
	VMCOREINFO_SIZE(nodemask_t);
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	VMCOREINFO_OFFSET(page, flags);
	VMCOREINFO_OFFSET(page, _count);
	VMCOREINFO_OFFSET(page, mapping);
	VMCOREINFO_OFFSET(page, lru);
	VMCOREINFO_OFFSET(pglist_data, node_zones);
	VMCOREINFO_OFFSET(pglist_data, nr_zones);
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#ifdef CONFIG_FLAT_NODE_MEM_MAP
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	VMCOREINFO_OFFSET(pglist_data, node_mem_map);
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#endif
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	VMCOREINFO_OFFSET(pglist_data, node_start_pfn);
	VMCOREINFO_OFFSET(pglist_data, node_spanned_pages);
	VMCOREINFO_OFFSET(pglist_data, node_id);
	VMCOREINFO_OFFSET(zone, free_area);
	VMCOREINFO_OFFSET(zone, vm_stat);
	VMCOREINFO_OFFSET(zone, spanned_pages);
	VMCOREINFO_OFFSET(free_area, free_list);
	VMCOREINFO_OFFSET(list_head, next);
	VMCOREINFO_OFFSET(list_head, prev);
	VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
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	VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
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	VMCOREINFO_NUMBER(NR_FREE_PAGES);
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	VMCOREINFO_NUMBER(PG_lru);
	VMCOREINFO_NUMBER(PG_private);
	VMCOREINFO_NUMBER(PG_swapcache);
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	arch_crash_save_vmcoreinfo();

	return 0;
}

module_init(crash_save_vmcoreinfo_init)