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kexec jump

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This patch provides an enhancement to kexec/kdump.  It implements the
following features:

- Backup/restore memory used by the original kernel before/after
  kexec.

- Save/restore CPU state before/after kexec.

The features of this patch can be used as a general method to call program in
physical mode (paging turning off).  This can be used to call BIOS code under
Linux.

kexec-tools needs to be patched to support kexec jump. The patches and
the precompiled kexec can be download from the following URL:

       source: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-src_git_kh10.tar.bz2
       patches: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-patches_git_kh10.tar.bz2
       binary: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec_git_kh10

Usage example of calling some physical mode code and return:

1. Compile and install patched kernel with following options selected:

CONFIG_X86_32=y
CONFIG_KEXEC=y
CONFIG_PM=y
CONFIG_KEXEC_JUMP=y

2. Build patched kexec-tool or download the pre-built one.

3. Build some physical mode executable named such as "phy_mode"

4. Boot kernel compiled in step 1.

5. Load physical mode executable with /sbin/kexec. The shell command
   line can be as follow:

   /sbin/kexec --load-preserve-context --args-none phy_mode

6. Call physical mode executable with following shell command line:

   /sbin/kexec -e

Implementation point:

To support jumping without reserving memory.  One shadow backup page (source
page) is allocated for each page used by kexeced code image (destination
page).  When do kexec_load, the image of kexeced code is loaded into source
pages, and before executing, the destination pages and the source pages are
swapped, so the contents of destination pages are backupped.  Before jumping
to the kexeced code image and after jumping back to the original kernel, the
destination pages and the source pages are swapped too.

C ABI (calling convention) is used as communication protocol between
kernel and called code.

A flag named KEXEC_PRESERVE_CONTEXT for sys_kexec_load is added to
indicate that the loaded kernel image is used for jumping back.

Now, only the i386 architecture is supported.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Huang Ying 2008-07-25 19:45:07 -07:00 committed by Linus Torvalds
parent 7fccf03265
commit 3ab8352137
10 changed files with 270 additions and 69 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/powerpc/kernel/machine_kexec.c
View file

@ -48,7 +48,7 @@ void machine_kexec_cleanup(struct kimage *image)
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
NORET_TYPE void machine_kexec(struct kimage *image)
void machine_kexec(struct kimage *image)
{
if (ppc_md.machine_kexec)
ppc_md.machine_kexec(image);

2
arch/sh/kernel/machine_kexec.c
View file

@ -70,7 +70,7 @@ static void kexec_info(struct kimage *image)
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
NORET_TYPE void machine_kexec(struct kimage *image)
void machine_kexec(struct kimage *image)
{
unsigned long page_list;

7
arch/x86/Kconfig
View file

@ -1279,6 +1279,13 @@ config CRASH_DUMP
(CONFIG_RELOCATABLE=y).
For more details see Documentation/kdump/kdump.txt
config KEXEC_JUMP
bool "kexec jump (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on KEXEC && PM_SLEEP && X86_32
help
Invoke code in physical address mode via KEXEC
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
default "0x1000000" if X86_NUMAQ

27
arch/x86/kernel/machine_kexec_32.c
View file

@ -22,6 +22,7 @@
#include <asm/cpufeature.h>
#include <asm/desc.h>
#include <asm/system.h>
#include <asm/cacheflush.h>
#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
static u32 kexec_pgd[1024] PAGE_ALIGNED;
@ -85,10 +86,12 @@ static void load_segments(void)
* reboot code buffer to allow us to avoid allocations
* later.
*
* Currently nothing.
* Make control page executable.
*/
int machine_kexec_prepare(struct kimage *image)
{
if (nx_enabled)
set_pages_x(image->control_code_page, 1);
return 0;
}
@ -98,16 +101,24 @@ int machine_kexec_prepare(struct kimage *image)
*/
void machine_kexec_cleanup(struct kimage *image)
{
if (nx_enabled)
set_pages_nx(image->control_code_page, 1);
}
/*
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
NORET_TYPE void machine_kexec(struct kimage *image)
void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
void *control_page;
asmlinkage unsigned long
(*relocate_kernel_ptr)(unsigned long indirection_page,
unsigned long control_page,
unsigned long start_address,
unsigned int has_pae,
unsigned int preserve_context);
tracer_disable();
@ -115,10 +126,11 @@ NORET_TYPE void machine_kexec(struct kimage *image)
local_irq_disable();
control_page = page_address(image->control_code_page);
memcpy(control_page, relocate_kernel, PAGE_SIZE);
memcpy(control_page, relocate_kernel, PAGE_SIZE/2);
relocate_kernel_ptr = control_page;
page_list[PA_CONTROL_PAGE] = __pa(control_page);
page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
page_list[PA_PGD] = __pa(kexec_pgd);
page_list[VA_PGD] = (unsigned long)kexec_pgd;
#ifdef CONFIG_X86_PAE
@ -131,6 +143,7 @@ NORET_TYPE void machine_kexec(struct kimage *image)
page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
page_list[PA_PTE_1] = __pa(kexec_pte1);
page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) << PAGE_SHIFT);
/* The segment registers are funny things, they have both a
* visible and an invisible part. Whenever the visible part is
@ -149,8 +162,10 @@ NORET_TYPE void machine_kexec(struct kimage *image)
set_idt(phys_to_virt(0),0);
/* now call it */
relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
image->start, cpu_has_pae);
image->start = relocate_kernel_ptr((unsigned long)image->head,
(unsigned long)page_list,
image->start, cpu_has_pae,
image->preserve_context);
}
void arch_crash_save_vmcoreinfo(void)

2
arch/x86/kernel/machine_kexec_64.c
View file

@ -181,7 +181,7 @@ void machine_kexec_cleanup(struct kimage *image)
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
NORET_TYPE void machine_kexec(struct kimage *image)
void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
void *control_page;

176
arch/x86/kernel/relocate_kernel_32.S
View file

@ -20,11 +20,44 @@
#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
#define PAE_PGD_ATTR (_PAGE_PRESENT)
/* control_page + PAGE_SIZE/2 ~ control_page + PAGE_SIZE * 3/4 are
* used to save some data for jumping back
*/
#define DATA(offset) (PAGE_SIZE/2+(offset))
/* Minimal CPU state */
#define ESP DATA(0x0)
#define CR0 DATA(0x4)
#define CR3 DATA(0x8)
#define CR4 DATA(0xc)
/* other data */
#define CP_VA_CONTROL_PAGE DATA(0x10)
#define CP_PA_PGD DATA(0x14)
#define CP_PA_SWAP_PAGE DATA(0x18)
#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
.text
.align PAGE_SIZE
.globl relocate_kernel
relocate_kernel:
movl 8(%esp), %ebp /* list of pages */
/* Save the CPU context, used for jumping back */
pushl %ebx
pushl %esi
pushl %edi
pushl %ebp
pushf
movl 20+8(%esp), %ebp /* list of pages */
movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
movl %esp, ESP(%edi)
movl %cr0, %eax
movl %eax, CR0(%edi)
movl %cr3, %eax
movl %eax, CR3(%edi)
movl %cr4, %eax
movl %eax, CR4(%edi)
#ifdef CONFIG_X86_PAE
/* map the control page at its virtual address */
@ -138,15 +171,25 @@ relocate_kernel:
relocate_new_kernel:
/* read the arguments and say goodbye to the stack */
movl 4(%esp), %ebx /* page_list */
movl 8(%esp), %ebp /* list of pages */
movl 12(%esp), %edx /* start address */
movl 16(%esp), %ecx /* cpu_has_pae */
movl 20+4(%esp), %ebx /* page_list */
movl 20+8(%esp), %ebp /* list of pages */
movl 20+12(%esp), %edx /* start address */
movl 20+16(%esp), %ecx /* cpu_has_pae */
movl 20+20(%esp), %esi /* preserve_context */
/* zero out flags, and disable interrupts */
pushl $0
popfl
/* save some information for jumping back */
movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
movl %edi, CP_VA_CONTROL_PAGE(%edi)
movl PTR(PA_PGD)(%ebp), %eax
movl %eax, CP_PA_PGD(%edi)
movl PTR(PA_SWAP_PAGE)(%ebp), %eax
movl %eax, CP_PA_SWAP_PAGE(%edi)
movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
/* get physical address of control page now */
/* this is impossible after page table switch */
movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
@ -197,8 +240,90 @@ identity_mapped:
xorl %eax, %eax
movl %eax, %cr3
movl CP_PA_SWAP_PAGE(%edi), %eax
pushl %eax
pushl %ebx
call swap_pages
addl $8, %esp
/* To be certain of avoiding problems with self-modifying code
* I need to execute a serializing instruction here.
* So I flush the TLB, it's handy, and not processor dependent.
*/
xorl %eax, %eax
movl %eax, %cr3
/* set all of the registers to known values */
/* leave %esp alone */
testl %esi, %esi
jnz 1f
xorl %edi, %edi
xorl %eax, %eax
xorl %ebx, %ebx
xorl %ecx, %ecx
xorl %edx, %edx
xorl %esi, %esi
xorl %ebp, %ebp
ret
1:
popl %edx
movl CP_PA_SWAP_PAGE(%edi), %esp
addl $PAGE_SIZE, %esp
2:
call *%edx
/* get the re-entry point of the peer system */
movl 0(%esp), %ebp
call 1f
1:
popl %ebx
subl $(1b - relocate_kernel), %ebx
movl CP_VA_CONTROL_PAGE(%ebx), %edi
lea PAGE_SIZE(%ebx), %esp
movl CP_PA_SWAP_PAGE(%ebx), %eax
movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
pushl %eax
pushl %edx
call swap_pages
addl $8, %esp
movl CP_PA_PGD(%ebx), %eax
movl %eax, %cr3
movl %cr0, %eax
orl $(1<<31), %eax
movl %eax, %cr0
lea PAGE_SIZE(%edi), %esp
movl %edi, %eax
addl $(virtual_mapped - relocate_kernel), %eax
pushl %eax
ret
virtual_mapped:
movl CR4(%edi), %eax
movl %eax, %cr4
movl CR3(%edi), %eax
movl %eax, %cr3
movl CR0(%edi), %eax
movl %eax, %cr0
movl ESP(%edi), %esp
movl %ebp, %eax
popf
popl %ebp
popl %edi
popl %esi
popl %ebx
ret
/* Do the copies */
movl %ebx, %ecx
swap_pages:
movl 8(%esp), %edx
movl 4(%esp), %ecx
pushl %ebp
pushl %ebx
pushl %edi
pushl %esi
movl %ecx, %ebx
jmp 1f
0: /* top, read another word from the indirection page */
@ -226,27 +351,28 @@ identity_mapped:
movl %ecx, %esi /* For every source page do a copy */
andl $0xfffff000, %esi
movl %edi, %eax
movl %esi, %ebp
movl %edx, %edi
movl $1024, %ecx
rep ; movsl
movl %ebp, %edi
movl %eax, %esi
movl $1024, %ecx
rep ; movsl
movl %eax, %edi
movl %edx, %esi
movl $1024, %ecx
rep ; movsl
lea PAGE_SIZE(%ebp), %esi
jmp 0b
3:
/* To be certain of avoiding problems with self-modifying code
* I need to execute a serializing instruction here.
* So I flush the TLB, it's handy, and not processor dependent.
*/
xorl %eax, %eax
movl %eax, %cr3
/* set all of the registers to known values */
/* leave %esp alone */
xorl %eax, %eax
xorl %ebx, %ebx
xorl %ecx, %ecx
xorl %edx, %edx
xorl %esi, %esi
xorl %edi, %edi
xorl %ebp, %ebp
popl %esi
popl %edi
popl %ebx
popl %ebp
ret

18
include/asm-x86/kexec.h
View file

@ -10,14 +10,15 @@
# define VA_PTE_0 5
# define PA_PTE_1 6
# define VA_PTE_1 7
# define PA_SWAP_PAGE 8
# ifdef CONFIG_X86_PAE
# define PA_PMD_0 8
# define VA_PMD_0 9
# define PA_PMD_1 10
# define VA_PMD_1 11
# define PAGES_NR 12
# define PA_PMD_0 9
# define VA_PMD_0 10
# define PA_PMD_1 11
# define VA_PMD_1 12
# define PAGES_NR 13
# else
# define PAGES_NR 8
# define PAGES_NR 9
# endif
#else
# define PA_CONTROL_PAGE 0
@ -152,11 +153,12 @@ static inline void crash_setup_regs(struct pt_regs *newregs,
}
#ifdef CONFIG_X86_32
asmlinkage NORET_TYPE void
asmlinkage unsigned long
relocate_kernel(unsigned long indirection_page,
unsigned long control_page,
unsigned long start_address,
unsigned int has_pae) ATTRIB_NORET;
unsigned int has_pae,
unsigned int preserve_context);
#else
NORET_TYPE void
relocate_kernel(unsigned long indirection_page,

17
include/linux/kexec.h
View file

@ -83,6 +83,7 @@ struct kimage {
unsigned long start;
struct page *control_code_page;
struct page *swap_page;
unsigned long nr_segments;
struct kexec_segment segment[KEXEC_SEGMENT_MAX];
@ -98,18 +99,20 @@ struct kimage {
unsigned int type : 1;
#define KEXEC_TYPE_DEFAULT 0
#define KEXEC_TYPE_CRASH 1
unsigned int preserve_context : 1;
};
/* kexec interface functions */
extern NORET_TYPE void machine_kexec(struct kimage *image) ATTRIB_NORET;
extern void machine_kexec(struct kimage *image);
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);
extern int kernel_kexec(void);
#ifdef CONFIG_COMPAT
extern asmlinkage long compat_sys_kexec_load(unsigned long entry,
unsigned long nr_segments,
@ -156,8 +159,9 @@ extern struct kimage *kexec_crash_image;
#define kexec_flush_icache_page(page)
#endif
#define KEXEC_ON_CRASH 0x00000001
#define KEXEC_ARCH_MASK 0xffff0000
#define KEXEC_ON_CRASH 0x00000001
#define KEXEC_PRESERVE_CONTEXT 0x00000002
#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.
@ -174,7 +178,12 @@ extern struct kimage *kexec_crash_image;
#define KEXEC_ARCH_MIPS_LE (10 << 16)
#define KEXEC_ARCH_MIPS ( 8 << 16)
#define KEXEC_FLAGS (KEXEC_ON_CRASH) /* List of defined/legal kexec flags */
/* List of defined/legal kexec flags */
#ifndef CONFIG_KEXEC_JUMP
#define KEXEC_FLAGS KEXEC_ON_CRASH
#else
#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT)
#endif
#define VMCOREINFO_BYTES (4096)
#define VMCOREINFO_NOTE_NAME "VMCOREINFO"

57
kernel/kexec.c
View file

@ -24,6 +24,8 @@
#include <linux/utsrelease.h>
#include <linux/utsname.h>
#include <linux/numa.h>
#include <linux/suspend.h>
#include <linux/device.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@ -242,6 +244,12 @@ static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
goto out;
}
image->swap_page = kimage_alloc_control_pages(image, 0);
if (!image->swap_page) {
printk(KERN_ERR "Could not allocate swap buffer\n");
goto out;
}
result = 0;
out:
if (result == 0)
@ -986,6 +994,8 @@ asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
if (result)
goto out;
if (flags & KEXEC_PRESERVE_CONTEXT)
image->preserve_context = 1;
result = machine_kexec_prepare(image);
if (result)
goto out;
@ -1411,3 +1421,50 @@ static int __init crash_save_vmcoreinfo_init(void)
}
module_init(crash_save_vmcoreinfo_init)
/**
* kernel_kexec - reboot the system
*
* 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 (xchg(&kexec_lock, 1))
return -EBUSY;
if (!kexec_image) {
error = -EINVAL;
goto Unlock;
}
if (kexec_image->preserve_context) {
#ifdef CONFIG_KEXEC_JUMP
local_irq_disable();
save_processor_state();
#endif
} else {
blocking_notifier_call_chain(&reboot_notifier_list,
SYS_RESTART, NULL);
system_state = SYSTEM_RESTART;
device_shutdown();
sysdev_shutdown();
printk(KERN_EMERG "Starting new kernel\n");
machine_shutdown();
}
machine_kexec(kexec_image);
if (kexec_image->preserve_context) {
#ifdef CONFIG_KEXEC_JUMP
restore_processor_state();
local_irq_enable();
#endif
}
Unlock:
xchg(&kexec_lock, 0);
return error;
}

31
kernel/sys.c
View file

@ -301,26 +301,6 @@ void kernel_restart(char *cmd)
}
EXPORT_SYMBOL_GPL(kernel_restart);
/**
* kernel_kexec - reboot the system
*
* Move into place and start executing a preloaded standalone
* executable. If nothing was preloaded return an error.
*/
static void kernel_kexec(void)
{
#ifdef CONFIG_KEXEC
struct kimage *image;
image = xchg(&kexec_image, NULL);
if (!image)
return;
kernel_restart_prepare(NULL);
printk(KERN_EMERG "Starting new kernel\n");
machine_shutdown();
machine_kexec(image);
#endif
}
static void kernel_shutdown_prepare(enum system_states state)
{
blocking_notifier_call_chain(&reboot_notifier_list,
@ -425,10 +405,15 @@ asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd, void __user
kernel_restart(buffer);
break;
#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
kernel_kexec();
unlock_kernel();
return -EINVAL;
{
int ret;
ret = kernel_kexec();
unlock_kernel();
return ret;
}
#endif
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND: