path: root/kernel/kexec.c
diff options
authorHuang Ying <ying.huang@intel.com>2008-07-25 19:45:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-26 12:00:04 -0700
commit3ab83521378268044a448113c6aa9a9e245f4d2f (patch)
treee9e8496577e4b2e994edf204e9a8ae7c026eec95 /kernel/kexec.c
parent7fccf0326536c1b245b98740d489abb9aab69a12 (diff)
kexec jump
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>
Diffstat (limited to 'kernel/kexec.c')
1 files changed, 57 insertions, 0 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 6db42ff8d52..a0d920915b3 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -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;
if (result == 0)
@@ -986,6 +994,8 @@ asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
if (result)
goto out;
+ 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)
+ * 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) {
+ local_irq_disable();
+ save_processor_state();
+ } else {
+ blocking_notifier_call_chain(&reboot_notifier_list,
+ 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) {
+ restore_processor_state();
+ local_irq_enable();
+ }
+ Unlock:
+ xchg(&kexec_lock, 0);
+ return error;