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![Simon Horman](/assets/img/avatar_default.png)
Currently the size of the per-cpu region reserved to save crash notes is set by the per-architecture value MAX_NOTE_BYTES. Which in turn is currently set to 1024 on all supported architectures. While testing ia64 I recently discovered that this value is in fact too small. The particular setup I was using actually needs 1172 bytes. This lead to very tedious failure mode where the tail of one elf note would overwrite the head of another if they ended up being alocated sequentially by kmalloc, which was often the case. It seems to me that a far better approach is to caclculate the size that the area needs to be. This patch does just that. If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is needed then this should be as easy as making MAX_NOTE_BYTES larger in arch/asm-ia64/kexec.h. Perhaps 2048 would be a good choice. However, I think that the approach in this patch is a much more robust idea. Acked-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Simon Horman <horms@verge.net.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1137 lines
29 KiB
C
1137 lines
29 KiB
C
/*
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* kexec.c - kexec system call
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* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/capability.h>
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/kexec.h>
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/highmem.h>
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#include <linux/syscalls.h>
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#include <linux/reboot.h>
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#include <linux/syscalls.h>
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#include <linux/ioport.h>
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#include <linux/hardirq.h>
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#include <linux/elf.h>
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#include <linux/elfcore.h>
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#include <asm/page.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <asm/system.h>
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#include <asm/semaphore.h>
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/* Per cpu memory for storing cpu states in case of system crash. */
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note_buf_t* crash_notes;
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/* Location of the reserved area for the crash kernel */
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struct resource crashk_res = {
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.name = "Crash kernel",
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.start = 0,
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.end = 0,
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.flags = IORESOURCE_BUSY | IORESOURCE_MEM
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};
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int kexec_should_crash(struct task_struct *p)
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{
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if (in_interrupt() || !p->pid || is_init(p) || panic_on_oops)
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return 1;
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return 0;
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}
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/*
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* When kexec transitions to the new kernel there is a one-to-one
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* mapping between physical and virtual addresses. On processors
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* where you can disable the MMU this is trivial, and easy. For
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* others it is still a simple predictable page table to setup.
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*
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* In that environment kexec copies the new kernel to its final
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* resting place. This means I can only support memory whose
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* physical address can fit in an unsigned long. In particular
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* addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
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* If the assembly stub has more restrictive requirements
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* KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
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* defined more restrictively in <asm/kexec.h>.
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*
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* The code for the transition from the current kernel to the
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* the new kernel is placed in the control_code_buffer, whose size
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* is given by KEXEC_CONTROL_CODE_SIZE. In the best case only a single
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* page of memory is necessary, but some architectures require more.
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* Because this memory must be identity mapped in the transition from
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* virtual to physical addresses it must live in the range
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* 0 - TASK_SIZE, as only the user space mappings are arbitrarily
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* modifiable.
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*
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* The assembly stub in the control code buffer is passed a linked list
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* of descriptor pages detailing the source pages of the new kernel,
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* and the destination addresses of those source pages. As this data
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* structure is not used in the context of the current OS, it must
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* be self-contained.
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*
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* The code has been made to work with highmem pages and will use a
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* destination page in its final resting place (if it happens
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* to allocate it). The end product of this is that most of the
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* physical address space, and most of RAM can be used.
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*
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* Future directions include:
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* - allocating a page table with the control code buffer identity
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* mapped, to simplify machine_kexec and make kexec_on_panic more
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* reliable.
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*/
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/*
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* KIMAGE_NO_DEST is an impossible destination address..., for
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* allocating pages whose destination address we do not care about.
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*/
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#define KIMAGE_NO_DEST (-1UL)
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static int kimage_is_destination_range(struct kimage *image,
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unsigned long start, unsigned long end);
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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,
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struct kexec_segment __user *segments)
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{
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size_t segment_bytes;
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struct kimage *image;
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unsigned long i;
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int result;
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/* Allocate a controlling structure */
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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;
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image->entry = &image->head;
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image->last_entry = &image->head;
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image->control_page = ~0; /* By default this does not apply */
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image->start = entry;
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image->type = KEXEC_TYPE_DEFAULT;
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/* Initialize the list of control pages */
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INIT_LIST_HEAD(&image->control_pages);
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/* Initialize the list of destination pages */
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INIT_LIST_HEAD(&image->dest_pages);
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/* Initialize the list of unuseable pages */
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INIT_LIST_HEAD(&image->unuseable_pages);
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/* Read in the segments */
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image->nr_segments = nr_segments;
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segment_bytes = nr_segments * sizeof(*segments);
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result = copy_from_user(image->segment, segments, segment_bytes);
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if (result)
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goto out;
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/*
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* Verify we have good destination addresses. The caller is
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* responsible for making certain we don't attempt to load
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* the new image into invalid or reserved areas of RAM. This
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* just verifies it is an address we can use.
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*
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* Since the kernel does everything in page size chunks ensure
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* the destination addreses are page aligned. Too many
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* special cases crop of when we don't do this. The most
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* insidious is getting overlapping destination addresses
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* simply because addresses are changed to page size
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* granularity.
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*/
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result = -EADDRNOTAVAIL;
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for (i = 0; i < nr_segments; i++) {
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unsigned long mstart, mend;
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mstart = image->segment[i].mem;
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mend = mstart + image->segment[i].memsz;
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if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
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goto out;
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if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
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goto out;
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}
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/* Verify our destination addresses do not overlap.
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* If we alloed overlapping destination addresses
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* through very weird things can happen with no
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* easy explanation as one segment stops on another.
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*/
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result = -EINVAL;
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for (i = 0; i < nr_segments; i++) {
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unsigned long mstart, mend;
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unsigned long j;
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mstart = image->segment[i].mem;
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mend = mstart + image->segment[i].memsz;
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for (j = 0; j < i; j++) {
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unsigned long pstart, pend;
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pstart = image->segment[j].mem;
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pend = pstart + image->segment[j].memsz;
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/* Do the segments overlap ? */
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if ((mend > pstart) && (mstart < pend))
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goto out;
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}
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}
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/* Ensure our buffer sizes are strictly less than
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* our memory sizes. This should always be the case,
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* and it is easier to check up front than to be surprised
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* later on.
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*/
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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)
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goto out;
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}
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result = 0;
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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;
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}
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static int kimage_normal_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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{
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int result;
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struct kimage *image;
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/* Allocate and initialize a controlling structure */
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image = NULL;
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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;
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/*
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* Find a location for the control code buffer, and add it
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* the vector of segments so that it's pages will also be
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* counted as destination pages.
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*/
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result = -ENOMEM;
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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) {
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printk(KERN_ERR "Could not allocate control_code_buffer\n");
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goto out;
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}
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result = 0;
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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;
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}
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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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{
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int result;
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struct kimage *image;
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unsigned long i;
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image = NULL;
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/* Verify we have a valid entry point */
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if ((entry < crashk_res.start) || (entry > crashk_res.end)) {
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result = -EADDRNOTAVAIL;
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goto out;
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}
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/* Allocate and initialize a controlling structure */
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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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/* Enable the special crash kernel control page
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* allocation policy.
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*/
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image->control_page = crashk_res.start;
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image->type = KEXEC_TYPE_CRASH;
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/*
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* Verify we have good destination addresses. Normally
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* the caller is responsible for making certain we don't
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* attempt to load the new image into invalid or reserved
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* areas of RAM. But crash kernels are preloaded into a
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* reserved area of ram. We must ensure the addresses
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* are in the reserved area otherwise preloading the
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* kernel could corrupt things.
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*/
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result = -EADDRNOTAVAIL;
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for (i = 0; i < nr_segments; i++) {
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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 */
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if ((mstart < crashk_res.start) || (mend > crashk_res.end))
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goto out;
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}
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/*
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* Find a location for the control code buffer, and add
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* the vector of segments so that it's pages will also be
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* counted as destination pages.
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*/
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result = -ENOMEM;
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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) {
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printk(KERN_ERR "Could not allocate control_code_buffer\n");
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goto out;
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}
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result = 0;
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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;
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}
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static int kimage_is_destination_range(struct kimage *image,
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unsigned long start,
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unsigned long end)
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{
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unsigned long i;
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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;
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mend = mstart + image->segment[i].memsz;
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if ((end > mstart) && (start < mend))
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return 1;
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}
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return 0;
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}
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static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
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{
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struct page *pages;
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pages = alloc_pages(gfp_mask, order);
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if (pages) {
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unsigned int count, i;
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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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}
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return pages;
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}
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static void kimage_free_pages(struct page *page)
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{
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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);
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__free_pages(page, order);
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}
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static void kimage_free_page_list(struct list_head *list)
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{
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struct list_head *pos, *next;
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list_for_each_safe(pos, next, list) {
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struct page *page;
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page = list_entry(pos, struct page, lru);
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list_del(&page->lru);
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kimage_free_pages(page);
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}
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}
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static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
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unsigned int order)
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{
|
|
/* Control pages are special, they are the intermediaries
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* that are needed while we copy the rest of the pages
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* to their final resting place. As such they must
|
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* not conflict with either the destination addresses
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* or memory the kernel is already using.
|
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*
|
|
* 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
|
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* page table for all of the memory.
|
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*
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* At worst this runs in O(N) of the image size.
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*/
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struct list_head extra_pages;
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struct page *pages;
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unsigned int count;
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count = 1 << order;
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INIT_LIST_HEAD(&extra_pages);
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|
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/* Loop while I can allocate a page and the page allocated
|
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* is a destination page.
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*/
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do {
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unsigned long pfn, epfn, addr, eaddr;
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|
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pages = kimage_alloc_pages(GFP_KERNEL, order);
|
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if (!pages)
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break;
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pfn = page_to_pfn(pages);
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epfn = pfn + count;
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addr = pfn << PAGE_SHIFT;
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eaddr = epfn << PAGE_SHIFT;
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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);
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pages = NULL;
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}
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} while (!pages);
|
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|
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if (pages) {
|
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/* Remember the allocated page... */
|
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list_add(&pages->lru, &image->control_pages);
|
|
|
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/* 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[].
|
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*/
|
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}
|
|
/* 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.
|
|
*/
|
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kimage_free_page_list(&extra_pages);
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|
|
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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,
|
|
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_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);
|
|
kexec_flush_icache_page(page);
|
|
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;
|
|
struct kimage *kexec_crash_image;
|
|
/*
|
|
* A home grown binary mutex.
|
|
* Nothing can wait so this mutex is safe to use
|
|
* in interrupt context :)
|
|
*/
|
|
static int kexec_lock;
|
|
|
|
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:
|
|
locked = xchg(&kexec_lock, 0); /* Release the mutex */
|
|
BUG_ON(!locked);
|
|
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)
|
|
{
|
|
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) {
|
|
if (kexec_crash_image) {
|
|
struct pt_regs fixed_regs;
|
|
crash_setup_regs(&fixed_regs, regs);
|
|
machine_crash_shutdown(&fixed_regs);
|
|
machine_kexec(kexec_crash_image);
|
|
}
|
|
locked = xchg(&kexec_lock, 0);
|
|
BUG_ON(!locked);
|
|
}
|
|
}
|
|
|
|
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, ¬e, 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, ¬e, 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);
|
|
buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
|
|
&prstatus, sizeof(prstatus));
|
|
final_note(buf);
|
|
}
|
|
|
|
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)
|