// SPDX-License-Identifier: GPL-2.0-only
/*
* kexec.c - kexec system call core code.
* Copyright (C) 2002-2004 Eric Biederman <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/btf.h>
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/kexec.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/syscalls.h>
#include <linux/reboot.h>
#include <linux/ioport.h>
#include <linux/hardirq.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/utsname.h>
#include <linux/numa.h>
#include <linux/suspend.h>
#include <linux/device.h>
#include <linux/freezer.h>
#include <linux/panic_notifier.h>
#include <linux/pm.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/console.h>
#include <linux/vmalloc.h>
#include <linux/swap.h>
#include <linux/syscore_ops.h>
#include <linux/compiler.h>
#include <linux/hugetlb.h>
#include <linux/objtool.h>
#include <linux/kmsg_dump.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <crypto/hash.h>
#include "kexec_internal.h"
atomic_t __kexec_lock = ATOMIC_INIT(0);
/* Flag to indicate we are going to kexec a new kernel */
bool kexec_in_progress = false;
bool kexec_file_dbg_print;
/*
* 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
* new kernel is placed in the control_code_buffer, whose size
* is given by KEXEC_CONTROL_PAGE_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)
#define PAGE_COUNT(x) (((x) + PAGE_SIZE - 1) >> PAGE_SHIFT)
static struct page *kimage_alloc_page(struct kimage *image,
gfp_t gfp_mask,
unsigned long dest);
int sanity_check_segment_list(struct kimage *image)
{
int i;
unsigned long nr_segments = image->nr_segments;
unsigned long total_pages = 0;
unsigned long nr_pages = totalram_pages();
/*
* 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 addresses 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.
*/
for (i = 0; i < nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
if (mstart > mend)
return -EADDRNOTAVAIL;
if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
return -EADDRNOTAVAIL;
if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
return -EADDRNOTAVAIL;
}
/* 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.
*/
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))
return -EINVAL;
}
}
/* 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.
*/
for (i = 0; i < nr_segments; i++) {
if (image->segment[i].bufsz > image->segment[i].memsz)
return -EINVAL;
}
/*
* Verify that no more than half of memory will be consumed. If the
* request from userspace is too large, a large amount of time will be
* wasted allocating pages, which can cause a soft lockup.
*/
for (i = 0; i < nr_segments; i++) {
if (PAGE_COUNT(image->segment[i].memsz) > nr_pages / 2)
return -EINVAL;
total_pages += PAGE_COUNT(image->segment[i].memsz);
}
if (total_pages > nr_pages / 2)
return -EINVAL;
#ifdef CONFIG_CRASH_DUMP
/*
* 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.
*/
if (image->type == KEXEC_TYPE_CRASH) {
for (i = 0; i < nr_segments; i++) {
unsigned long mstart, mend;
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz - 1;
/* Ensure we are within the crash kernel limits */
if ((mstart < phys_to_boot_phys(crashk_res.start)) ||
(mend > phys_to_boot_phys(crashk_res.end)))
return -EADDRNOTAVAIL;
}
}
#endif
return 0;
}
struct kimage *do_kimage_alloc_init(void)
{
struct kimage *image;
/* Allocate a controlling structure */
image = kzalloc(sizeof(*image), GFP_KERNEL);
if (!image)
return NULL;
image->head = 0;
image->entry = &image->head;
image->last_entry = &image->head;
image->control_page = ~0; /* By default this does not apply */
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 unusable pages */
INIT_LIST_HEAD(&image->unusable_pages);
#ifdef CONFIG_CRASH_HOTPLUG
image->hp_action = KEXEC_CRASH_HP_NONE;
image->elfcorehdr_index = -1;
image->elfcorehdr_updated = false;
#endif
return image;
}
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 - 1;
if ((end >= mstart) && (start <= mend))
return 1;
}
return 0;
}
static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
{
struct page *pages;
if (fatal_signal_pending(current))
return NULL;
pages = alloc_pages(gfp_mask & ~__GFP_ZERO, order);
if (pages) {
unsigned int count, i;
pages->mapping = NULL;
set_page_private(pages, order);
count = 1 << order;
for (i = 0; i < count; i++)
SetPageReserved(pages + i);
arch_kexec_post_alloc_pages(page_address(pages), count,
gfp_mask);
if (gfp_mask & __GFP_ZERO)
for (i = 0; i < count; i++)
clear_highpage(pages + i);
}
return pages;
}
static void kimage_free_pages(struct page *page)
{
unsigned int order, count, i;
order = page_private(page);
count = 1 << order;
arch_kexec_pre_free_pages(page_address(page), count);
for (i = 0; i < count; i++)
ClearPageReserved(page + i);
__free_pages(page, order);
}
void kimage_free_page_list(struct list_head *list)
{
struct page *page, *next;
list_for_each_entry_safe(page, next, list, 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(KEXEC_CONTROL_MEMORY_GFP, order);
if (!pages)
break;
pfn = page_to_boot_pfn(pages);
epfn = pfn + count;
addr = pfn << PAGE_SHIFT;
eaddr = (epfn << PAGE_SHIFT) - 1;
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 everything to image->dest_pages.
*
* For now it is simpler to just free the pages.
*/
kimage_free_page_list(&extra_pages);
return pages;
}
#ifdef CONFIG_CRASH_DUMP
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 = ALIGN(image->control_page, size);
hole_end = hole_start + size - 1;
while (hole_end <= crashk_res.end) {
unsigned long i;
cond_resched();
if (hole_end > KEXEC_CRASH_CONTROL_MEMORY_LIMIT)
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 = ALIGN(mend, size);
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);
image->control_page = hole_end + 1;
break;
}
}
/* Ensure that these pages are decrypted if SME is enabled. */
if (pages)
arch_kexec_post_alloc_pages(page_address(pages), 1 << order, 0);
return pages;
}
#endif
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;
#ifdef CONFIG_CRASH_DUMP
case KEXEC_TYPE_CRASH:
pages = kimage_alloc_crash_control_pages(image, order);
break;
#endif
}
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_boot_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)
{
destination &= PAGE_MASK;
return kimage_add_entry(image, destination | IND_DESTINATION);
}
static int kimage_add_page(struct kimage *image, unsigned long page)
{
page &= PAGE_MASK;
return kimage_add_entry(image, page | IND_SOURCE);
}
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 unusable pages I have cached */
kimage_free_page_list(&image->unusable_pages);
}
void kimage_terminate(struct kimage *image)
{
if (*image->entry != 0)
image->entry++;
*image->entry = IND_DONE;
}
#define for_each_kimage_entry(image, ptr, entry) \
for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
ptr = (entry & IND_INDIRECTION) ? \
boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
static void kimage_free_entry(kimage_entry_t entry)
{
struct page *page;
page = boot_pfn_to_page(entry >> PAGE_SHIFT);
kimage_free_pages(page);
}
void kimage_free(struct kimage *image)
{
kimage_entry_t *ptr, entry;
kimage_entry_t ind = 0;
if (!image)
return;
#ifdef CONFIG_CRASH_DUMP
if (image->vmcoreinfo_data_copy) {
crash_update_vmcoreinfo_safecopy(NULL);
vunmap(image->vmcoreinfo_data_copy);
}
#endif
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);
/*
* Free up any temporary buffers allocated. This might hit if
* error occurred much later after buffer allocation.
*/
if (image->file_mode)
kimage_file_post_load_cleanup(image);
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_boot_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_boot_pfn(page) >
(KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {
list_add(&page->lru, &image->unusable_pages);
continue;
}
addr = page_to_boot_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 - 1))
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 = boot_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 if it's
* gfp_flags honor the ones passed in.
*/
if (!(gfp_mask & __GFP_HIGHMEM) &&
PageHighMem(old_page)) {
kimage_free_pages(old_page);
continue;
}
page = old_page;
break;
}
/* Place the page on the destination list, to be used 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;
size_t ubytes, mbytes;
int result;
unsigned char __user *buf = NULL;
unsigned char *kbuf = NULL;
if (image->file_mode)
kbuf = segment->kbuf;
else
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) {
result = -ENOMEM;
goto out;
}
result = kimage_add_page(image, page_to_boot_pfn(page)
<< PAGE_SHIFT);
if (result < 0)
goto out;
ptr = kmap_local_page(page);
/* Start with a clear page */
clear_page(ptr);
ptr += maddr & ~PAGE_MASK;
mchunk = min_t(size_t, mbytes,
PAGE_SIZE - (maddr & ~PAGE_MASK));
uchunk = min(ubytes, mchunk);
if (uchunk) {
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
ubytes -= uchunk;
if (image->file_mode)
kbuf += uchunk;
else
buf += uchunk;
}
kunmap_local(ptr);
if (result) {
result = -EFAULT;
goto out;
}
maddr += mchunk;
mbytes -= mchunk;
cond_resched();
}
out:
return result;
}
#ifdef CONFIG_CRASH_DUMP
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;
size_t ubytes, mbytes;
int result;
unsigned char __user *buf = NULL;
unsigned char *kbuf = NULL;
result = 0;
if (image->file_mode)
kbuf = segment->kbuf;
else
buf = segment->buf;
ubytes = segment->bufsz;
mbytes = segment->memsz;
maddr = segment->mem;
while (mbytes) {
struct page *page;
char *ptr;
size_t uchunk, mchunk;
page = boot_pfn_to_page(maddr >> PAGE_SHIFT);
if (!page) {
result = -ENOMEM;
goto out;
}
arch_kexec_post_alloc_pages(page_address(page), 1, 0);
ptr = kmap_local_page(page);
ptr += maddr & ~PAGE_MASK;
mchunk = min_t(size_t, mbytes,
PAGE_SIZE - (maddr & ~PAGE_MASK));
uchunk = min(ubytes, mchunk);
if (mchunk > uchunk) {
/* Zero the trailing part of the page */
memset(ptr + uchunk, 0, mchunk - uchunk);
}
if (uchunk) {
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
ubytes -= uchunk;
if (image->file_mode)
kbuf += uchunk;
else
buf += uchunk;
}
kexec_flush_icache_page(page);
kunmap_local(ptr);
arch_kexec_pre_free_pages(page_address(page), 1);
if (result) {
result = -EFAULT;
goto out;
}
maddr += mchunk;
mbytes -= mchunk;
cond_resched();
}
out:
return result;
}
#endif
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;
#ifdef CONFIG_CRASH_DUMP
case KEXEC_TYPE_CRASH:
result = kimage_load_crash_segment(image, segment);
break;
#endif
}
return result;
}
struct kexec_load_limit {
/* Mutex protects the limit count. */
struct mutex mutex;
int limit;
};
static struct kexec_load_limit load_limit_reboot = {
.mutex = __MUTEX_INITIALIZER(load_limit_reboot.mutex),
.limit = -1,
};
static struct kexec_load_limit load_limit_panic = {
.mutex = __MUTEX_INITIALIZER(load_limit_panic.mutex),
.limit = -1,
};
struct kimage *kexec_image;
struct kimage *kexec_crash_image;
static int kexec_load_disabled;
#ifdef CONFIG_SYSCTL
static int kexec_limit_handler(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct kexec_load_limit *limit = table->data;
int val;
struct ctl_table tmp = {
.data = &val,
.maxlen = sizeof(val),
.mode = table->mode,
};
int ret;
if (write) {
ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
if (ret)
return ret;
if (val < 0)
return -EINVAL;
mutex_lock(&limit->mutex);
if (limit->limit != -1 && val >= limit->limit)
ret = -EINVAL;
else
limit->limit = val;
mutex_unlock(&limit->mutex);
return ret;
}
mutex_lock(&limit->mutex);
val = limit->limit;
mutex_unlock(&limit->mutex);
return proc_dointvec(&tmp, write, buffer, lenp, ppos);
}
static struct ctl_table kexec_core_sysctls[] = {
{
.procname = "kexec_load_disabled",
.data = &kexec_load_disabled,
.maxlen = sizeof(int),
.mode = 0644,
/* only handle a transition from default "0" to "1" */
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_ONE,
},
{
.procname = "kexec_load_limit_panic",
.data = &load_limit_panic,
.mode = 0644,
.proc_handler = kexec_limit_handler,
},
{
.procname = "kexec_load_limit_reboot",
.data = &load_limit_reboot,
.mode = 0644,
.proc_handler = kexec_limit_handler,
},
};
static int __init kexec_core_sysctl_init(void)
{
register_sysctl_init("kernel", kexec_core_sysctls);
return 0;
}
late_initcall(kexec_core_sysctl_init);
#endif
bool kexec_load_permitted(int kexec_image_type)
{
struct kexec_load_limit *limit;
/*
* Only the superuser can use the kexec syscall and if it has not
* been disabled.
*/
if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
return false;
/* Check limit counter and decrease it.*/
limit = (kexec_image_type == KEXEC_TYPE_CRASH) ?
&load_limit_panic : &load_limit_reboot;
mutex_lock(&limit->mutex);
if (!limit->limit) {
mutex_unlock(&limit->mutex);
return false;
}
if (limit->limit != -1)
limit->limit--;
mutex_unlock(&limit->mutex);
return true;
}
/*
* Move into place and start executing a preloaded standalone
* executable. If nothing was preloaded return an error.
*/
int kernel_kexec(void)
{
int error = 0;
if (!kexec_trylock())
return -EBUSY;
if (!kexec_image) {
error = -EINVAL;
goto Unlock;
}
#ifdef CONFIG_KEXEC_JUMP
if (kexec_image->preserve_context) {
pm_prepare_console();
error = freeze_processes();
if (error) {
error = -EBUSY;
goto Restore_console;
}
suspend_console();
error = dpm_suspend_start(PMSG_FREEZE);
if (error)
goto Resume_console;
/* At this point, dpm_suspend_start() has been called,
* but *not* dpm_suspend_end(). We *must* call
* dpm_suspend_end() now. Otherwise, drivers for
* some devices (e.g. interrupt controllers) become
* desynchronized with the actual state of the
* hardware at resume time, and evil weirdness ensues.
*/
error = dpm_suspend_end(PMSG_FREEZE);
if (error)
goto Resume_devices;
error = suspend_disable_secondary_cpus();
if (error)
goto Enable_cpus;
local_irq_disable();
error = syscore_suspend();
if (error)
goto Enable_irqs;
} else
#endif
{
kexec_in_progress = true;
kernel_restart_prepare("kexec reboot");
migrate_to_reboot_cpu();
syscore_shutdown();
/*
* migrate_to_reboot_cpu() disables CPU hotplug assuming that
* no further code needs to use CPU hotplug (which is true in
* the reboot case). However, the kexec path depends on using
* CPU hotplug again; so re-enable it here.
*/
cpu_hotplug_enable();
pr_notice("Starting new kernel\n");
machine_shutdown();
}
kmsg_dump(KMSG_DUMP_SHUTDOWN);
machine_kexec(kexec_image);
#ifdef CONFIG_KEXEC_JUMP
if (kexec_image->preserve_context) {
syscore_resume();
Enable_irqs:
local_irq_enable();
Enable_cpus:
suspend_enable_secondary_cpus();
dpm_resume_start(PMSG_RESTORE);
Resume_devices:
dpm_resume_end(PMSG_RESTORE);
Resume_console:
resume_console();
thaw_processes();
Restore_console:
pm_restore_console();
}
#endif
Unlock:
kexec_unlock();
return error;
}
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