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https://github.com/edk2-porting/linux-next.git
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9796fdd829
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1063 lines
27 KiB
C
1063 lines
27 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/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 <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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/* 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 || p->pid == 1 || 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 = kmalloc(sizeof(*image), GFP_KERNEL);
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if (!image)
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goto out;
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memset(image, 0, sizeof(*image));
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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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pages->private = 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;
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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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{
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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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*
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* The only case where we really need more than one of
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* these are for architectures where we cannot disable
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* 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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/* 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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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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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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|
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/* Because the page is already in it's destination
|
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* location we will never allocate another page at
|
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* that address. Therefore kimage_alloc_pages
|
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* will not return it (again) and we don't need
|
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* to give it an entry in image->segment[].
|
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*/
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}
|
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/* Deal with the destination pages I have inadvertently allocated.
|
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*
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* Ideally I would convert multi-page allocations into single
|
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* page allocations, and add everyting to image->dest_pages.
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*
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* For now it is simpler to just free the pages.
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*/
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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,
|
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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;
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|
struct page *pages;
|
|
|
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pages = NULL;
|
|
size = (1 << order) << PAGE_SHIFT;
|
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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)
|
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break;
|
|
/* See if I overlap any of the segments */
|
|
for (i = 0; i < image->nr_segments; i++) {
|
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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;
|
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}
|
|
}
|
|
/* 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);
|
|
kunmap(page);
|
|
if (result) {
|
|
result = (result < 0) ? result : -EIO;
|
|
goto out;
|
|
}
|
|
ubytes -= uchunk;
|
|
maddr += mchunk;
|
|
buf += mchunk;
|
|
mbytes -= mchunk;
|
|
}
|
|
out:
|
|
return result;
|
|
}
|
|
|
|
static int kimage_load_segment(struct kimage *image,
|
|
struct kexec_segment *segment)
|
|
{
|
|
int result = -ENOMEM;
|
|
|
|
switch (image->type) {
|
|
case KEXEC_TYPE_DEFAULT:
|
|
result = kimage_load_normal_segment(image, segment);
|
|
break;
|
|
case KEXEC_TYPE_CRASH:
|
|
result = kimage_load_crash_segment(image, segment);
|
|
break;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* Exec Kernel system call: for obvious reasons only root may call it.
|
|
*
|
|
* This call breaks up into three pieces.
|
|
* - A generic part which loads the new kernel from the current
|
|
* address space, and very carefully places the data in the
|
|
* allocated pages.
|
|
*
|
|
* - A generic part that interacts with the kernel and tells all of
|
|
* the devices to shut down. Preventing on-going dmas, and placing
|
|
* the devices in a consistent state so a later kernel can
|
|
* reinitialize them.
|
|
*
|
|
* - A machine specific part that includes the syscall number
|
|
* and the copies the image to it's final destination. And
|
|
* jumps into the image at entry.
|
|
*
|
|
* kexec does not sync, or unmount filesystems so if you need
|
|
* that to happen you need to do that yourself.
|
|
*/
|
|
struct kimage *kexec_image = NULL;
|
|
static struct kimage *kexec_crash_image = NULL;
|
|
/*
|
|
* A home grown binary mutex.
|
|
* Nothing can wait so this mutex is safe to use
|
|
* in interrupt context :)
|
|
*/
|
|
static int kexec_lock = 0;
|
|
|
|
asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
|
|
struct kexec_segment __user *segments,
|
|
unsigned long flags)
|
|
{
|
|
struct kimage **dest_image, *image;
|
|
int locked;
|
|
int result;
|
|
|
|
/* We only trust the superuser with rebooting the system. */
|
|
if (!capable(CAP_SYS_BOOT))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* Verify we have a legal set of flags
|
|
* This leaves us room for future extensions.
|
|
*/
|
|
if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
|
|
return -EINVAL;
|
|
|
|
/* Verify we are on the appropriate architecture */
|
|
if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
|
|
((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
|
|
return -EINVAL;
|
|
|
|
/* Put an artificial cap on the number
|
|
* of segments passed to kexec_load.
|
|
*/
|
|
if (nr_segments > KEXEC_SEGMENT_MAX)
|
|
return -EINVAL;
|
|
|
|
image = NULL;
|
|
result = 0;
|
|
|
|
/* Because we write directly to the reserved memory
|
|
* region when loading crash kernels we need a mutex here to
|
|
* prevent multiple crash kernels from attempting to load
|
|
* simultaneously, and to prevent a crash kernel from loading
|
|
* over the top of a in use crash kernel.
|
|
*
|
|
* KISS: always take the mutex.
|
|
*/
|
|
locked = xchg(&kexec_lock, 1);
|
|
if (locked)
|
|
return -EBUSY;
|
|
|
|
dest_image = &kexec_image;
|
|
if (flags & KEXEC_ON_CRASH)
|
|
dest_image = &kexec_crash_image;
|
|
if (nr_segments > 0) {
|
|
unsigned long i;
|
|
|
|
/* Loading another kernel to reboot into */
|
|
if ((flags & KEXEC_ON_CRASH) == 0)
|
|
result = kimage_normal_alloc(&image, entry,
|
|
nr_segments, segments);
|
|
/* Loading another kernel to switch to if this one crashes */
|
|
else if (flags & KEXEC_ON_CRASH) {
|
|
/* Free any current crash dump kernel before
|
|
* we corrupt it.
|
|
*/
|
|
kimage_free(xchg(&kexec_crash_image, NULL));
|
|
result = kimage_crash_alloc(&image, entry,
|
|
nr_segments, segments);
|
|
}
|
|
if (result)
|
|
goto out;
|
|
|
|
result = machine_kexec_prepare(image);
|
|
if (result)
|
|
goto out;
|
|
|
|
for (i = 0; i < nr_segments; i++) {
|
|
result = kimage_load_segment(image, &image->segment[i]);
|
|
if (result)
|
|
goto out;
|
|
}
|
|
result = kimage_terminate(image);
|
|
if (result)
|
|
goto out;
|
|
}
|
|
/* Install the new kernel, and Uninstall the old */
|
|
image = xchg(dest_image, image);
|
|
|
|
out:
|
|
xchg(&kexec_lock, 0); /* Release the mutex */
|
|
kimage_free(image);
|
|
|
|
return result;
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
asmlinkage long compat_sys_kexec_load(unsigned long entry,
|
|
unsigned long nr_segments,
|
|
struct compat_kexec_segment __user *segments,
|
|
unsigned long flags)
|
|
{
|
|
struct compat_kexec_segment in;
|
|
struct kexec_segment out, __user *ksegments;
|
|
unsigned long i, result;
|
|
|
|
/* Don't allow clients that don't understand the native
|
|
* architecture to do anything.
|
|
*/
|
|
if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
|
|
return -EINVAL;
|
|
|
|
if (nr_segments > KEXEC_SEGMENT_MAX)
|
|
return -EINVAL;
|
|
|
|
ksegments = compat_alloc_user_space(nr_segments * sizeof(out));
|
|
for (i=0; i < nr_segments; i++) {
|
|
result = copy_from_user(&in, &segments[i], sizeof(in));
|
|
if (result)
|
|
return -EFAULT;
|
|
|
|
out.buf = compat_ptr(in.buf);
|
|
out.bufsz = in.bufsz;
|
|
out.mem = in.mem;
|
|
out.memsz = in.memsz;
|
|
|
|
result = copy_to_user(&ksegments[i], &out, sizeof(out));
|
|
if (result)
|
|
return -EFAULT;
|
|
}
|
|
|
|
return sys_kexec_load(entry, nr_segments, ksegments, flags);
|
|
}
|
|
#endif
|
|
|
|
void crash_kexec(struct pt_regs *regs)
|
|
{
|
|
struct kimage *image;
|
|
int locked;
|
|
|
|
|
|
/* Take the kexec_lock here to prevent sys_kexec_load
|
|
* running on one cpu from replacing the crash kernel
|
|
* we are using after a panic on a different cpu.
|
|
*
|
|
* If the crash kernel was not located in a fixed area
|
|
* of memory the xchg(&kexec_crash_image) would be
|
|
* sufficient. But since I reuse the memory...
|
|
*/
|
|
locked = xchg(&kexec_lock, 1);
|
|
if (!locked) {
|
|
image = xchg(&kexec_crash_image, NULL);
|
|
if (image) {
|
|
machine_crash_shutdown(regs);
|
|
machine_kexec(image);
|
|
}
|
|
xchg(&kexec_lock, 0);
|
|
}
|
|
}
|