linux.git/kernel/kexec.c, branch v2.6.27-rc4

kexec: use a mutex for locking rather than xchg()

2008-08-15T15:35:43+00:00

Functionally the same, but more conventional.

Cc: Huang Ying 
Tested-by: Vivek Goyal 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: fix for ftrace

2008-08-15T15:35:43+00:00

Ftrace depends on some processor state that we destroyed during kexec and
restored by restore_processor_state().  So save_processor_state() and
restore_processor_state() are moved into machine_kexec() and ftrace is
restored after restore_processor_state().

Signed-off-by: Huang Ying 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Eric W. Biederman" 
Cc: Vivek Goyal 
Cc: Ingo Molnar 
Cc: Steven Rostedt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: in sync with hibernation implementation

2008-08-15T15:35:42+00:00

Add device_pm_lock() and device_pm_unlock() in kernel_kexec() in sync with
current hibernation implementation.

Signed-off-by: Huang Ying 
Acked-by: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Eric W. Biederman" 
Cc: Vivek Goyal 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: remove duplication of kexec_restart_prepare()

2008-08-15T15:35:42+00:00

Call kernel_restart_prepare() in kernel_kexec() instead of duplicating the
code.

Signed-off-by: Huang Ying 
Acked-by: Pavel Machek 
Acked-by: Vivek Goyal 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Eric W. Biederman" 
Cc: Vivek Goyal 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: rename KEXEC_CONTROL_CODE_SIZE to KEXEC_CONTROL_PAGE_SIZE

2008-08-15T15:35:42+00:00

Rename KEXEC_CONTROL_CODE_SIZE to KEXEC_CONTROL_PAGE_SIZE, because control
page is used for not only code on some platform.  For example in kexec
jump, it is used for data and stack too.

[akpm@linux-foundation.org: unbreak powerpc and arm, finish conversion]
Signed-off-by: Huang Ying 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Eric W. Biederman" 
Cc: Vivek Goyal 
Cc: Ingo Molnar 
Cc: Russell King 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: clean up #ifdef and comments

2008-08-15T15:35:42+00:00

Move if (kexec_image->preserve_context) { ...  } into #ifdef
CONFIG_KEXEC_JUMP to make code looks cleaner.

Fix no longer correct comments of kernel_kexec().

Signed-off-by: Huang Ying 
Acked-by: Vivek Goyal 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Eric W. Biederman" 
Cc: Vivek Goyal 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec: fix compilation warning on xchg(&kexec_lock, 0) in kernel_kexec()

2008-08-15T15:35:42+00:00

kernel/kexec.c: In function 'kernel_kexec':
kernel/kexec.c:1506: warning: value computed is not used

Signed-off-by: Huang Ying 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump: save/restore device state

2008-07-26T19:00:04+00:00

This patch implements devices state save/restore before after kexec.

This patch together with features in kexec_jump patch can be used for
following:

- A simple hibernation implementation without ACPI support.  You can kexec a
  hibernating kernel, save the memory image of original system and shutdown
  the system.  When resuming, you restore the memory image of original system
  via ordinary kexec load then jump back.

- Kernel/system debug through making system snapshot.  You can make system
  snapshot, jump back, do some thing and make another system snapshot.

- Cooperative multi-kernel/system.  With kexec jump, you can switch between
  several kernels/systems quickly without boot process except the first time.
  This appears like swap a whole kernel/system out/in.

- A general method to call program in physical mode (paging turning
  off). This can be used to invoke BIOS code under Linux.

The following user-space tools can be used with kexec jump:

- 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

- makedumpfile with patches are used as memory image saving tool, it
  can exclude free pages from original kernel memory image file. The
  patches and the precompiled makedumpfile can be download from the
  following URL:
       source: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile-src_cvs_kh10.tar.bz2
       patches: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile-patches_cvs_kh10.tar.bz2
       binary: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile_cvs_kh10

- An initramfs image can be used as the root file system of kexeced
  kernel. An initramfs image built with "BuildRoot" can be downloaded
  from the following URL:
       initramfs image: http://khibernation.sourceforge.net/download/release_v10/initramfs/rootfs_cvs_kh10.gz
  All user space tools above are included in the initramfs image.

Usage example of simple hibernation:

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

CONFIG_X86_32=y
CONFIG_RELOCATABLE=y
CONFIG_KEXEC=y
CONFIG_CRASH_DUMP=y
CONFIG_PM=y
CONFIG_HIBERNATION=y
CONFIG_KEXEC_JUMP=y

2. Build an initramfs image contains kexec-tool and makedumpfile, or
   download the pre-built initramfs image, called rootfs.gz in
   following text.

3. Prepare a partition to save memory image of original kernel, called
   hibernating partition in following text.

4. Boot kernel compiled in step 1 (kernel A).

5. In the kernel A, load kernel compiled in step 1 (kernel B) with
   /sbin/kexec. The shell command line can be as follow:

   /sbin/kexec --load-preserve-context /boot/bzImage --mem-min=0x100000
     --mem-max=0xffffff --initrd=rootfs.gz

6. Boot the kernel B with following shell command line:

   /sbin/kexec -e

7. The kernel B will boot as normal kexec. In kernel B the memory
   image of kernel A can be saved into hibernating partition as
   follow:

   jump_back_entry=`cat /proc/cmdline | tr ' ' '\n' | grep kexec_jump_back_entry | cut -d '='`
   echo $jump_back_entry > kexec_jump_back_entry
   cp /proc/vmcore dump.elf

   Then you can shutdown the machine as normal.

8. Boot kernel compiled in step 1 (kernel C). Use the rootfs.gz as
   root file system.

9. In kernel C, load the memory image of kernel A as follow:

   /sbin/kexec -l --args-none --entry=`cat kexec_jump_back_entry` dump.elf

10. Jump back to the kernel A as follow:

   /sbin/kexec -e

   Then, kernel A is resumed.

Implementation point:

To support jumping between two kernels, before jumping to (executing)
the new kernel and jumping back to the original kernel, the devices
are put into quiescent state, and the state of devices and CPU is
saved. After jumping back from kexeced kernel and jumping to the new
kernel, the state of devices and CPU are restored accordingly. The
devices/CPU state save/restore code of software suspend is called to
implement corresponding function.

Known issues:

- Because the segment number supported by sys_kexec_load is limited,
  hibernation image with many segments may not be load. This is
  planned to be eliminated by adding a new flag to sys_kexec_load to
  make a image can be loaded with multiple sys_kexec_load invoking.

Now, only the i386 architecture is supported.

Signed-off-by: Huang Ying 
Acked-by: Vivek Goyal 
Cc: "Eric W. Biederman" 
Cc: Pavel Machek 
Cc: Nigel Cunningham 
Cc: "Rafael J. Wysocki" 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec jump

2008-07-26T19:00:04+00:00

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 
Acked-by: Vivek Goyal 
Cc: "Eric W. Biederman" 
Cc: Pavel Machek 
Cc: Nigel Cunningham 
Cc: "Rafael J. Wysocki" 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/kexec.c: make 'kimage_terminate' void

2008-07-26T19:00:04+00:00

Since kimage_terminate() always returns 0, make it void.

Signed-off-by: WANG Cong 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds