https://github.com/torvalds/linux
Revision 7a3136666bc0f0419f7aaa7b1fabb4b0e0a7fb76 authored by Kees Cook on 07 July 2011, 01:10:34 UTC, committed by H. Peter Anvin on 07 July 2011, 03:09:34 UTC
Some BIOSes will reset the Intel MISC_ENABLE MSR (specifically the
XD_DISABLE bit) when resuming from S3, which can interact poorly with
ebba638ae723d8a8fc2f7abce5ec18b688b791d7. In 32bit PAE mode, this can
lead to a fault when EFER is restored by the kernel wakeup routines,
due to it setting the NX bit for a CPU that (thanks to the BIOS reset)
now incorrectly thinks it lacks the NX feature. (64bit is not affected
because it uses a common CPU bring-up that specifically handles the
XD_DISABLE bit.)

The need for MISC_ENABLE being restored so early is specific to the S3
resume path. Normally, MISC_ENABLE is saved in save_processor_state(),
but this happens after the resume header is created, so just reproduce
the logic here. (acpi_suspend_lowlevel() creates the header, calls
do_suspend_lowlevel, which calls save_processor_state(), so the saved
processor context isn't available during resume header creation.)

[ hpa: Consider for stable if OK in mainline ]

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Link: http://lkml.kernel.org/r/20110707011034.GA8523@outflux.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@kernel.org> 2.6.38+
1 parent b49c78d
Raw File
Tip revision: 7a3136666bc0f0419f7aaa7b1fabb4b0e0a7fb76 authored by Kees Cook on 07 July 2011, 01:10:34 UTC
x86, suspend: Restore MISC_ENABLE MSR in realmode wakeup
Tip revision: 7a31366
Kconfig
#
# Configuration for initramfs
#

config INITRAMFS_SOURCE
	string "Initramfs source file(s)"
	default ""
	help
	  This can be either a single cpio archive with a .cpio suffix or a
	  space-separated list of directories and files for building the
	  initramfs image.  A cpio archive should contain a filesystem archive
	  to be used as an initramfs image.  Directories should contain a
	  filesystem layout to be included in the initramfs image.  Files
	  should contain entries according to the format described by the
	  "usr/gen_init_cpio" program in the kernel tree.

	  When multiple directories and files are specified then the
	  initramfs image will be the aggregate of all of them.

	  See <file:Documentation/early-userspace/README> for more details.

	  If you are not sure, leave it blank.

config INITRAMFS_ROOT_UID
	int "User ID to map to 0 (user root)"
	depends on INITRAMFS_SOURCE!=""
	default "0"
	help
	  This setting is only meaningful if the INITRAMFS_SOURCE is
	  contains a directory.  Setting this user ID (UID) to something
	  other than "0" will cause all files owned by that UID to be
	  owned by user root in the initial ramdisk image.

	  If you are not sure, leave it set to "0".

config INITRAMFS_ROOT_GID
	int "Group ID to map to 0 (group root)"
	depends on INITRAMFS_SOURCE!=""
	default "0"
	help
	  This setting is only meaningful if the INITRAMFS_SOURCE is
	  contains a directory.  Setting this group ID (GID) to something
	  other than "0" will cause all files owned by that GID to be
	  owned by group root in the initial ramdisk image.

	  If you are not sure, leave it set to "0".

config RD_GZIP
	bool "Support initial ramdisks compressed using gzip" if EXPERT
	default y
	depends on BLK_DEV_INITRD
	select DECOMPRESS_GZIP
	help
	  Support loading of a gzip encoded initial ramdisk or cpio buffer.
	  If unsure, say Y.

config RD_BZIP2
	bool "Support initial ramdisks compressed using bzip2" if EXPERT
	default !EXPERT
	depends on BLK_DEV_INITRD
	select DECOMPRESS_BZIP2
	help
	  Support loading of a bzip2 encoded initial ramdisk or cpio buffer
	  If unsure, say N.

config RD_LZMA
	bool "Support initial ramdisks compressed using LZMA" if EXPERT
	default !EXPERT
	depends on BLK_DEV_INITRD
	select DECOMPRESS_LZMA
	help
	  Support loading of a LZMA encoded initial ramdisk or cpio buffer
	  If unsure, say N.

config RD_XZ
	bool "Support initial ramdisks compressed using XZ" if EXPERT
	default !EXPERT
	depends on BLK_DEV_INITRD
	select DECOMPRESS_XZ
	help
	  Support loading of a XZ encoded initial ramdisk or cpio buffer.
	  If unsure, say N.

config RD_LZO
	bool "Support initial ramdisks compressed using LZO" if EXPERT
	default !EXPERT
	depends on BLK_DEV_INITRD
	select DECOMPRESS_LZO
	help
	  Support loading of a LZO encoded initial ramdisk or cpio buffer
	  If unsure, say N.

choice
	prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
	help
	  This option decides by which algorithm the builtin initramfs
	  will be compressed.  Several compression algorithms are
	  available, which differ in efficiency, compression and
	  decompression speed.  Compression speed is only relevant
	  when building a kernel.  Decompression speed is relevant at
	  each boot.

	  If you have any problems with bzip2 or LZMA compressed
	  initramfs, mail me (Alain Knaff) <alain@knaff.lu>.

	  High compression options are mostly useful for users who are
	  low on RAM, since it reduces the memory consumption during
	  boot.

	  If in doubt, select 'gzip'

config INITRAMFS_COMPRESSION_NONE
	bool "None"
	help
	  Do not compress the built-in initramfs at all. This may
	  sound wasteful in space, but, you should be aware that the
	  built-in initramfs will be compressed at a later stage
	  anyways along with the rest of the kernel, on those
	  architectures that support this.
	  However, not compressing the initramfs may lead to slightly
	  higher memory consumption during a short time at boot, while
	  both the cpio image and the unpacked filesystem image will
	  be present in memory simultaneously

config INITRAMFS_COMPRESSION_GZIP
	bool "Gzip"
	depends on RD_GZIP
	help
	  The old and tried gzip compression. It provides a good balance
	  between compression ratio and decompression speed.

config INITRAMFS_COMPRESSION_BZIP2
	bool "Bzip2"
	depends on RD_BZIP2
	help
	  Its compression ratio and speed is intermediate.
	  Decompression speed is slowest among the four.  The initramfs
	  size is about 10% smaller with bzip2, in comparison to gzip.
	  Bzip2 uses a large amount of memory. For modern kernels you
	  will need at least 8MB RAM or more for booting.

config INITRAMFS_COMPRESSION_LZMA
	bool "LZMA"
	depends on RD_LZMA
	help
	  The most recent compression algorithm.
	  Its ratio is best, decompression speed is between the other
	  three. Compression is slowest. The initramfs size is about 33%
	  smaller with LZMA in comparison to gzip.

config INITRAMFS_COMPRESSION_XZ
	bool "XZ"
	depends on RD_XZ
	help
	  XZ uses the LZMA2 algorithm. The initramfs size is about 30%
	  smaller with XZ in comparison to gzip. Decompression speed
	  is better than that of bzip2 but worse than gzip and LZO.
	  Compression is slow.

config INITRAMFS_COMPRESSION_LZO
	bool "LZO"
	depends on RD_LZO
	help
	  Its compression ratio is the poorest among the four. The kernel
	  size is about 10% bigger than gzip; however its speed
	  (both compression and decompression) is the fastest.

endchoice
back to top