提交 dc009d92 编写于 作者: E Eric W. Biederman 提交者: Linus Torvalds

[PATCH] kexec: add kexec syscalls

This patch introduces the architecture independent implementation the
sys_kexec_load, the compat_sys_kexec_load system calls.

Kexec on panic support has been integrated into the core patch and is
relatively clean.

In addition the hopefully architecture independent option
crashkernel=size@location has been docuemented.  It's purpose is to reserve
space for the panic kernel to live, and where no DMA transfer will ever be
setup to access.
Signed-off-by: NEric Biederman <ebiederm@xmission.com>
Signed-off-by: NAlexander Nyberg <alexn@telia.com>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
上级 d0537508
......@@ -358,6 +358,10 @@ running once the system is up.
cpia_pp= [HW,PPT]
Format: { parport<nr> | auto | none }
crashkernel=nn[KMG]@ss[KMG]
[KNL] Reserve a chunk of physical memory to
hold a kernel to switch to with kexec on panic.
cs4232= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
......
......@@ -1330,6 +1330,16 @@ M: rml@novell.com
L: linux-kernel@vger.kernel.org
S: Maintained
KEXEC
P: Eric Biederman
P: Randy Dunlap
M: ebiederm@xmission.com
M: rddunlap@osdl.org
W: http://www.xmission.com/~ebiederm/files/kexec/
L: linux-kernel@vger.kernel.org
L: fastboot@osdl.org
S: Maintained
LANMEDIA WAN CARD DRIVER
P: Andrew Stanley-Jones
M: asj@lanmedia.com
......
#ifndef LINUX_KEXEC_H
#define LINUX_KEXEC_H
#ifdef CONFIG_KEXEC
#include <linux/types.h>
#include <linux/list.h>
#include <linux/linkage.h>
#include <linux/compat.h>
#include <asm/kexec.h>
/* Verify architecture specific macros are defined */
#ifndef KEXEC_SOURCE_MEMORY_LIMIT
#error KEXEC_SOURCE_MEMORY_LIMIT not defined
#endif
#ifndef KEXEC_DESTINATION_MEMORY_LIMIT
#error KEXEC_DESTINATION_MEMORY_LIMIT not defined
#endif
#ifndef KEXEC_CONTROL_MEMORY_LIMIT
#error KEXEC_CONTROL_MEMORY_LIMIT not defined
#endif
#ifndef KEXEC_CONTROL_CODE_SIZE
#error KEXEC_CONTROL_CODE_SIZE not defined
#endif
#ifndef KEXEC_ARCH
#error KEXEC_ARCH not defined
#endif
/*
* This structure is used to hold the arguments that are used when loading
* kernel binaries.
*/
typedef unsigned long kimage_entry_t;
#define IND_DESTINATION 0x1
#define IND_INDIRECTION 0x2
#define IND_DONE 0x4
#define IND_SOURCE 0x8
#define KEXEC_SEGMENT_MAX 8
struct kexec_segment {
void __user *buf;
size_t bufsz;
unsigned long mem; /* User space sees this as a (void *) ... */
size_t memsz;
};
#ifdef CONFIG_COMPAT
struct compat_kexec_segment {
compat_uptr_t buf;
compat_size_t bufsz;
compat_ulong_t mem; /* User space sees this as a (void *) ... */
compat_size_t memsz;
};
#endif
struct kimage {
kimage_entry_t head;
kimage_entry_t *entry;
kimage_entry_t *last_entry;
unsigned long destination;
unsigned long start;
struct page *control_code_page;
unsigned long nr_segments;
struct kexec_segment segment[KEXEC_SEGMENT_MAX];
struct list_head control_pages;
struct list_head dest_pages;
struct list_head unuseable_pages;
/* Address of next control page to allocate for crash kernels. */
unsigned long control_page;
/* Flags to indicate special processing */
unsigned int type : 1;
#define KEXEC_TYPE_DEFAULT 0
#define KEXEC_TYPE_CRASH 1
};
/* kexec interface functions */
extern NORET_TYPE void machine_kexec(struct kimage *image) ATTRIB_NORET;
extern int machine_kexec_prepare(struct kimage *image);
extern void machine_kexec_cleanup(struct kimage *image);
extern asmlinkage long sys_kexec_load(unsigned long entry,
unsigned long nr_segments, struct kexec_segment __user *segments,
unsigned long flags);
#ifdef CONFIG_COMPAT
extern asmlinkage long compat_sys_kexec_load(unsigned long entry,
unsigned long nr_segments, struct compat_kexec_segment __user *segments,
unsigned long flags);
#endif
extern struct page *kimage_alloc_control_pages(struct kimage *image, unsigned int order);
extern void crash_kexec(void);
extern struct kimage *kexec_image;
#define KEXEC_ON_CRASH 0x00000001
#define KEXEC_ARCH_MASK 0xffff0000
/* These values match the ELF architecture values.
* Unless there is a good reason that should continue to be the case.
*/
#define KEXEC_ARCH_DEFAULT ( 0 << 16)
#define KEXEC_ARCH_386 ( 3 << 16)
#define KEXEC_ARCH_X86_64 (62 << 16)
#define KEXEC_ARCH_PPC (20 << 16)
#define KEXEC_ARCH_PPC64 (21 << 16)
#define KEXEC_ARCH_IA_64 (50 << 16)
#define KEXEC_FLAGS (KEXEC_ON_CRASH) /* List of defined/legal kexec flags */
/* Location of a reserved region to hold the crash kernel.
*/
extern struct resource crashk_res;
#else /* !CONFIG_KEXEC */
static inline void crash_kexec(void) { }
#endif /* CONFIG_KEXEC */
#endif /* LINUX_KEXEC_H */
......@@ -51,6 +51,9 @@ extern void machine_restart(char *cmd);
extern void machine_halt(void);
extern void machine_power_off(void);
extern void machine_shutdown(void);
extern void machine_crash_shutdown(void);
#endif
#endif /* _LINUX_REBOOT_H */
......@@ -159,8 +159,9 @@ asmlinkage long sys_shutdown(int, int);
asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd,
void __user *arg);
asmlinkage long sys_restart_syscall(void);
asmlinkage long sys_kexec_load(void *entry, unsigned long nr_segments,
struct kexec_segment *segments, unsigned long flags);
asmlinkage long sys_kexec_load(unsigned long entry,
unsigned long nr_segments, struct kexec_segment __user *segments,
unsigned long flags);
asmlinkage long sys_exit(int error_code);
asmlinkage void sys_exit_group(int error_code);
......
......@@ -17,6 +17,7 @@ obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_PM) += power/
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_CPUSETS) += cpuset.o
obj-$(CONFIG_IKCONFIG) += configs.o
......
/*
* kexec.c - kexec system call
* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/kexec.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/syscalls.h>
#include <linux/reboot.h>
#include <linux/syscalls.h>
#include <linux/ioport.h>
#include <asm/page.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/semaphore.h>
/* Location of the reserved area for the crash kernel */
struct resource crashk_res = {
.name = "Crash kernel",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_MEM
};
/*
* When kexec transitions to the new kernel there is a one-to-one
* mapping between physical and virtual addresses. On processors
* where you can disable the MMU this is trivial, and easy. For
* others it is still a simple predictable page table to setup.
*
* In that environment kexec copies the new kernel to its final
* resting place. This means I can only support memory whose
* physical address can fit in an unsigned long. In particular
* addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
* If the assembly stub has more restrictive requirements
* KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
* defined more restrictively in <asm/kexec.h>.
*
* The code for the transition from the current kernel to the
* the new kernel is placed in the control_code_buffer, whose size
* is given by KEXEC_CONTROL_CODE_SIZE. In the best case only a single
* page of memory is necessary, but some architectures require more.
* Because this memory must be identity mapped in the transition from
* virtual to physical addresses it must live in the range
* 0 - TASK_SIZE, as only the user space mappings are arbitrarily
* modifiable.
*
* The assembly stub in the control code buffer is passed a linked list
* of descriptor pages detailing the source pages of the new kernel,
* and the destination addresses of those source pages. As this data
* structure is not used in the context of the current OS, it must
* be self-contained.
*
* The code has been made to work with highmem pages and will use a
* destination page in its final resting place (if it happens
* to allocate it). The end product of this is that most of the
* physical address space, and most of RAM can be used.
*
* Future directions include:
* - allocating a page table with the control code buffer identity
* mapped, to simplify machine_kexec and make kexec_on_panic more
* reliable.
*/
/*
* KIMAGE_NO_DEST is an impossible destination address..., for
* allocating pages whose destination address we do not care about.
*/
#define KIMAGE_NO_DEST (-1UL)
static int kimage_is_destination_range(
struct kimage *image, unsigned long start, unsigned long end);
static struct page *kimage_alloc_page(struct kimage *image, unsigned int gfp_mask, unsigned long dest);
static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
unsigned long nr_segments, struct kexec_segment __user *segments)
{
size_t segment_bytes;
struct kimage *image;
unsigned long i;
int result;
/* Allocate a controlling structure */
result = -ENOMEM;
image = kmalloc(sizeof(*image), GFP_KERNEL);
if (!image) {
goto out;
}
memset(image, 0, sizeof(*image));
image->head = 0;
image->entry = &image->head;
image->last_entry = &image->head;
image->control_page = ~0; /* By default this does not apply */
image->start = entry;
image->type = KEXEC_TYPE_DEFAULT;
/* Initialize the list of control pages */
INIT_LIST_HEAD(&image->control_pages);
/* Initialize the list of destination pages */
INIT_LIST_HEAD(&image->dest_pages);
/* Initialize the list of unuseable pages */
INIT_LIST_HEAD(&image->unuseable_pages);
/* Read in the segments */
image->nr_segments = nr_segments;
segment_bytes = nr_segments * sizeof(*segments);
result = copy_from_user(image->segment, segments, segment_bytes);
if (result)
goto out;
/*
* Verify we have good destination addresses. The caller is
* responsible for making certain we don't attempt to load
* the new image into invalid or reserved areas of RAM. This
* just verifies it is an address we can use.
*
* Since the kernel does everything in page size chunks ensure
* the destination addreses are page aligned. Too many
* special cases crop of when we don't do this. The most
* insidious is getting overlapping destination addresses
* simply because addresses are changed to page size
* granularity.
*/
result = -EADDRNOTAVAIL;
for (i = 0; i < nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
goto out;
if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
goto out;
}
/* Verify our destination addresses do not overlap.
* If we alloed overlapping destination addresses
* through very weird things can happen with no
* easy explanation as one segment stops on another.
*/
result = -EINVAL;
for(i = 0; i < nr_segments; i++) {
unsigned long mstart, mend;
unsigned long j;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
for(j = 0; j < i; j++) {
unsigned long pstart, pend;
pstart = image->segment[j].mem;
pend = pstart + image->segment[j].memsz;
/* Do the segments overlap ? */
if ((mend > pstart) && (mstart < pend))
goto out;
}
}
/* Ensure our buffer sizes are strictly less than
* our memory sizes. This should always be the case,
* and it is easier to check up front than to be surprised
* later on.
*/
result = -EINVAL;
for(i = 0; i < nr_segments; i++) {
if (image->segment[i].bufsz > image->segment[i].memsz)
goto out;
}
result = 0;
out:
if (result == 0) {
*rimage = image;
} else {
kfree(image);
}
return result;
}
static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
unsigned long nr_segments, struct kexec_segment __user *segments)
{
int result;
struct kimage *image;
/* Allocate and initialize a controlling structure */
image = NULL;
result = do_kimage_alloc(&image, entry, nr_segments, segments);
if (result) {
goto out;
}
*rimage = image;
/*
* Find a location for the control code buffer, and add it
* the vector of segments so that it's pages will also be
* counted as destination pages.
*/
result = -ENOMEM;
image->control_code_page = kimage_alloc_control_pages(image,
get_order(KEXEC_CONTROL_CODE_SIZE));
if (!image->control_code_page) {
printk(KERN_ERR "Could not allocate control_code_buffer\n");
goto out;
}
result = 0;
out:
if (result == 0) {
*rimage = image;
} else {
kfree(image);
}
return result;
}
static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
unsigned long nr_segments, struct kexec_segment *segments)
{
int result;
struct kimage *image;
unsigned long i;
image = NULL;
/* Verify we have a valid entry point */
if ((entry < crashk_res.start) || (entry > crashk_res.end)) {
result = -EADDRNOTAVAIL;
goto out;
}
/* Allocate and initialize a controlling structure */
result = do_kimage_alloc(&image, entry, nr_segments, segments);
if (result) {
goto out;
}
/* Enable the special crash kernel control page
* allocation policy.
*/
image->control_page = crashk_res.start;
image->type = KEXEC_TYPE_CRASH;
/*
* Verify we have good destination addresses. Normally
* the caller is responsible for making certain we don't
* attempt to load the new image into invalid or reserved
* areas of RAM. But crash kernels are preloaded into a
* reserved area of ram. We must ensure the addresses
* are in the reserved area otherwise preloading the
* kernel could corrupt things.
*/
result = -EADDRNOTAVAIL;
for (i = 0; i < nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
/* Ensure we are within the crash kernel limits */
if ((mstart < crashk_res.start) || (mend > crashk_res.end))
goto out;
}
/*
* Find a location for the control code buffer, and add
* the vector of segments so that it's pages will also be
* counted as destination pages.
*/
result = -ENOMEM;
image->control_code_page = kimage_alloc_control_pages(image,
get_order(KEXEC_CONTROL_CODE_SIZE));
if (!image->control_code_page) {
printk(KERN_ERR "Could not allocate control_code_buffer\n");
goto out;
}
result = 0;
out:
if (result == 0) {
*rimage = image;
} else {
kfree(image);
}
return result;
}
static int kimage_is_destination_range(
struct kimage *image, unsigned long start, unsigned long end)
{
unsigned long i;
for (i = 0; i < image->nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
if ((end > mstart) && (start < mend)) {
return 1;
}
}
return 0;
}
static struct page *kimage_alloc_pages(unsigned int gfp_mask, unsigned int order)
{
struct page *pages;
pages = alloc_pages(gfp_mask, order);
if (pages) {
unsigned int count, i;
pages->mapping = NULL;
pages->private = order;
count = 1 << order;
for(i = 0; i < count; i++) {
SetPageReserved(pages + i);
}
}
return pages;
}
static void kimage_free_pages(struct page *page)
{
unsigned int order, count, i;
order = page->private;
count = 1 << order;
for(i = 0; i < count; i++) {
ClearPageReserved(page + i);
}
__free_pages(page, order);
}
static void kimage_free_page_list(struct list_head *list)
{
struct list_head *pos, *next;
list_for_each_safe(pos, next, list) {
struct page *page;
page = list_entry(pos, struct page, lru);
list_del(&page->lru);
kimage_free_pages(page);
}
}
static struct page *kimage_alloc_normal_control_pages(
struct kimage *image, unsigned int order)
{
/* Control pages are special, they are the intermediaries
* that are needed while we copy the rest of the pages
* to their final resting place. As such they must
* not conflict with either the destination addresses
* or memory the kernel is already using.
*
* The only case where we really need more than one of
* these are for architectures where we cannot disable
* the MMU and must instead generate an identity mapped
* page table for all of the memory.
*
* At worst this runs in O(N) of the image size.
*/
struct list_head extra_pages;
struct page *pages;
unsigned int count;
count = 1 << order;
INIT_LIST_HEAD(&extra_pages);
/* Loop while I can allocate a page and the page allocated
* is a destination page.
*/
do {
unsigned long pfn, epfn, addr, eaddr;
pages = kimage_alloc_pages(GFP_KERNEL, order);
if (!pages)
break;
pfn = page_to_pfn(pages);
epfn = pfn + count;
addr = pfn << PAGE_SHIFT;
eaddr = epfn << PAGE_SHIFT;
if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
kimage_is_destination_range(image, addr, eaddr))
{
list_add(&pages->lru, &extra_pages);
pages = NULL;
}
} while(!pages);
if (pages) {
/* Remember the allocated page... */
list_add(&pages->lru, &image->control_pages);
/* Because the page is already in it's destination
* location we will never allocate another page at
* that address. Therefore kimage_alloc_pages
* will not return it (again) and we don't need
* to give it an entry in image->segment[].
*/
}
/* Deal with the destination pages I have inadvertently allocated.
*
* Ideally I would convert multi-page allocations into single
* page allocations, and add everyting to image->dest_pages.
*
* For now it is simpler to just free the pages.
*/
kimage_free_page_list(&extra_pages);
return pages;
}
static struct page *kimage_alloc_crash_control_pages(
struct kimage *image, unsigned int order)
{
/* Control pages are special, they are the intermediaries
* that are needed while we copy the rest of the pages
* to their final resting place. As such they must
* not conflict with either the destination addresses
* or memory the kernel is already using.
*
* Control pages are also the only pags we must allocate
* when loading a crash kernel. All of the other pages
* are specified by the segments and we just memcpy
* into them directly.
*
* The only case where we really need more than one of
* these are for architectures where we cannot disable
* the MMU and must instead generate an identity mapped
* page table for all of the memory.
*
* Given the low demand this implements a very simple
* allocator that finds the first hole of the appropriate
* size in the reserved memory region, and allocates all
* of the memory up to and including the hole.
*/
unsigned long hole_start, hole_end, size;
struct page *pages;
pages = NULL;
size = (1 << order) << PAGE_SHIFT;
hole_start = (image->control_page + (size - 1)) & ~(size - 1);
hole_end = hole_start + size - 1;
while(hole_end <= crashk_res.end) {
unsigned long i;
if (hole_end > KEXEC_CONTROL_MEMORY_LIMIT) {
break;
}
if (hole_end > crashk_res.end) {
break;
}
/* See if I overlap any of the segments */
for(i = 0; i < image->nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz - 1;
if ((hole_end >= mstart) && (hole_start <= mend)) {
/* Advance the hole to the end of the segment */
hole_start = (mend + (size - 1)) & ~(size - 1);
hole_end = hole_start + size - 1;
break;
}
}
/* If I don't overlap any segments I have found my hole! */
if (i == image->nr_segments) {
pages = pfn_to_page(hole_start >> PAGE_SHIFT);
break;
}
}
if (pages) {
image->control_page = hole_end;
}
return pages;
}
struct page *kimage_alloc_control_pages(
struct kimage *image, unsigned int order)
{
struct page *pages = NULL;
switch(image->type) {
case KEXEC_TYPE_DEFAULT:
pages = kimage_alloc_normal_control_pages(image, order);
break;
case KEXEC_TYPE_CRASH:
pages = kimage_alloc_crash_control_pages(image, order);
break;
}
return pages;
}
static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
{
if (*image->entry != 0) {
image->entry++;
}
if (image->entry == image->last_entry) {
kimage_entry_t *ind_page;
struct page *page;
page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);
if (!page) {
return -ENOMEM;
}
ind_page = page_address(page);
*image->entry = virt_to_phys(ind_page) | IND_INDIRECTION;
image->entry = ind_page;
image->last_entry =
ind_page + ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);
}
*image->entry = entry;
image->entry++;
*image->entry = 0;
return 0;
}
static int kimage_set_destination(
struct kimage *image, unsigned long destination)
{
int result;
destination &= PAGE_MASK;
result = kimage_add_entry(image, destination | IND_DESTINATION);
if (result == 0) {
image->destination = destination;
}
return result;
}
static int kimage_add_page(struct kimage *image, unsigned long page)
{
int result;
page &= PAGE_MASK;
result = kimage_add_entry(image, page | IND_SOURCE);
if (result == 0) {
image->destination += PAGE_SIZE;
}
return result;
}
static void kimage_free_extra_pages(struct kimage *image)
{
/* Walk through and free any extra destination pages I may have */
kimage_free_page_list(&image->dest_pages);
/* Walk through and free any unuseable pages I have cached */
kimage_free_page_list(&image->unuseable_pages);
}
static int kimage_terminate(struct kimage *image)
{
if (*image->entry != 0) {
image->entry++;
}
*image->entry = IND_DONE;
return 0;
}
#define for_each_kimage_entry(image, ptr, entry) \
for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
ptr = (entry & IND_INDIRECTION)? \
phys_to_virt((entry & PAGE_MASK)): ptr +1)
static void kimage_free_entry(kimage_entry_t entry)
{
struct page *page;
page = pfn_to_page(entry >> PAGE_SHIFT);
kimage_free_pages(page);
}
static void kimage_free(struct kimage *image)
{
kimage_entry_t *ptr, entry;
kimage_entry_t ind = 0;
if (!image)
return;
kimage_free_extra_pages(image);
for_each_kimage_entry(image, ptr, entry) {
if (entry & IND_INDIRECTION) {
/* Free the previous indirection page */
if (ind & IND_INDIRECTION) {
kimage_free_entry(ind);
}
/* Save this indirection page until we are
* done with it.
*/
ind = entry;
}
else if (entry & IND_SOURCE) {
kimage_free_entry(entry);
}
}
/* Free the final indirection page */
if (ind & IND_INDIRECTION) {
kimage_free_entry(ind);
}
/* Handle any machine specific cleanup */
machine_kexec_cleanup(image);
/* Free the kexec control pages... */
kimage_free_page_list(&image->control_pages);
kfree(image);
}
static kimage_entry_t *kimage_dst_used(struct kimage *image, unsigned long page)
{
kimage_entry_t *ptr, entry;
unsigned long destination = 0;
for_each_kimage_entry(image, ptr, entry) {
if (entry & IND_DESTINATION) {
destination = entry & PAGE_MASK;
}
else if (entry & IND_SOURCE) {
if (page == destination) {
return ptr;
}
destination += PAGE_SIZE;
}
}
return 0;
}
static struct page *kimage_alloc_page(struct kimage *image, unsigned int gfp_mask, unsigned long destination)
{
/*
* Here we implement safeguards to ensure that a source page
* is not copied to its destination page before the data on
* the destination page is no longer useful.
*
* To do this we maintain the invariant that a source page is
* either its own destination page, or it is not a
* destination page at all.
*
* That is slightly stronger than required, but the proof
* that no problems will not occur is trivial, and the
* implementation is simply to verify.
*
* When allocating all pages normally this algorithm will run
* in O(N) time, but in the worst case it will run in O(N^2)
* time. If the runtime is a problem the data structures can
* be fixed.
*/
struct page *page;
unsigned long addr;
/*
* Walk through the list of destination pages, and see if I
* have a match.
*/
list_for_each_entry(page, &image->dest_pages, lru) {
addr = page_to_pfn(page) << PAGE_SHIFT;
if (addr == destination) {
list_del(&page->lru);
return page;
}
}
page = NULL;
while (1) {
kimage_entry_t *old;
/* Allocate a page, if we run out of memory give up */
page = kimage_alloc_pages(gfp_mask, 0);
if (!page) {
return 0;
}
/* 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 *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 *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(void)
{
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();
machine_kexec(image);
}
xchg(&kexec_lock, 0);
}
}
......@@ -18,6 +18,7 @@
#include <linux/sysrq.h>
#include <linux/interrupt.h>
#include <linux/nmi.h>
#include <linux/kexec.h>
int panic_timeout;
int panic_on_oops;
......@@ -63,6 +64,13 @@ NORET_TYPE void panic(const char * fmt, ...)
unsigned long caller = (unsigned long) __builtin_return_address(0);
#endif
/*
* It's possible to come here directly from a panic-assertion and not
* have preempt disabled. Some functions called from here want
* preempt to be disabled. No point enabling it later though...
*/
preempt_disable();
bust_spinlocks(1);
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
......@@ -70,7 +78,19 @@ NORET_TYPE void panic(const char * fmt, ...)
printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
bust_spinlocks(0);
/*
* If we have crashed and we have a crash kernel loaded let it handle
* everything else.
* Do we want to call this before we try to display a message?
*/
crash_kexec();
#ifdef CONFIG_SMP
/*
* Note smp_send_stop is the usual smp shutdown function, which
* unfortunately means it may not be hardened to work in a panic
* situation.
*/
smp_send_stop();
#endif
......@@ -79,8 +99,7 @@ NORET_TYPE void panic(const char * fmt, ...)
if (!panic_blink)
panic_blink = no_blink;
if (panic_timeout > 0)
{
if (panic_timeout > 0) {
/*
* Delay timeout seconds before rebooting the machine.
* We can't use the "normal" timers since we just panicked..
......
......@@ -16,6 +16,8 @@
#include <linux/init.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/workqueue.h>
#include <linux/device.h>
#include <linux/key.h>
......@@ -439,6 +441,24 @@ asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd, void __user
machine_restart(buffer);
break;
#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
{
struct kimage *image;
image = xchg(&kexec_image, 0);
if (!image) {
unlock_kernel();
return -EINVAL;
}
notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
system_state = SYSTEM_RESTART;
device_shutdown();
printk(KERN_EMERG "Starting new kernel\n");
machine_shutdown();
machine_kexec(image);
break;
}
#endif
#ifdef CONFIG_SOFTWARE_SUSPEND
case LINUX_REBOOT_CMD_SW_SUSPEND:
{
......
......@@ -18,6 +18,8 @@ cond_syscall(sys_acct);
cond_syscall(sys_lookup_dcookie);
cond_syscall(sys_swapon);
cond_syscall(sys_swapoff);
cond_syscall(sys_kexec_load);
cond_syscall(compat_sys_kexec_load);
cond_syscall(sys_init_module);
cond_syscall(sys_delete_module);
cond_syscall(sys_socketpair);
......
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