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27 March 2024, 02:37:15 UTC
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 
x86, suspend: Restore MISC_ENABLE MSR in realmode wakeup
 
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
initramfs_data.S 
/*
  initramfs_data includes the compressed binary that is the
  filesystem used for early user space.
  Note: Older versions of "as" (prior to binutils 2.11.90.0.23
  released on 2001-07-14) dit not support .incbin.
  If you are forced to use older binutils than that then the
  following trick can be applied to create the resulting binary:


  ld -m elf_i386  --format binary --oformat elf32-i386 -r \
  -T initramfs_data.scr initramfs_data.cpio.gz -o initramfs_data.o
   ld -m elf_i386  -r -o built-in.o initramfs_data.o

  For including the .init.ramfs sections, see include/asm-generic/vmlinux.lds.

  The above example is for i386 - the parameters vary from architectures.
  Eventually look up LDFLAGS_BLOB in an older version of the
  arch/$(ARCH)/Makefile to see the flags used before .incbin was introduced.

  Using .incbin has the advantage over ld that the correct flags are set
  in the ELF header, as required by certain architectures.
*/

#include <linux/stringify.h>
#include <asm-generic/vmlinux.lds.h>

.section .init.ramfs,"a"
__irf_start:
.incbin __stringify(INITRAMFS_IMAGE)
__irf_end:
.section .init.ramfs.info,"a"
.globl VMLINUX_SYMBOL(__initramfs_size)
VMLINUX_SYMBOL(__initramfs_size):
#ifdef CONFIG_64BIT
	.quad __irf_end - __irf_start
#else
	.long __irf_end - __irf_start
#endif
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