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authorKees Cook <kees.cook@canonical.com>2011-07-06 18:10:34 -0700
committerH. Peter Anvin <hpa@zytor.com>2011-07-06 20:09:34 -0700
commit7a3136666bc0f0419f7aaa7b1fabb4b0e0a7fb76 (patch)
tree9d9e9f1de8ab1306b8b9d26aadb4a7f401323e69
parentb49c78d4827be8d7e67e5b94adac6b30a4a9ad14 (diff)
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+
-rw-r--r--arch/x86/kernel/acpi/realmode/wakeup.S14
-rw-r--r--arch/x86/kernel/acpi/realmode/wakeup.h6
-rw-r--r--arch/x86/kernel/acpi/sleep.c6
3 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.S b/arch/x86/kernel/acpi/realmode/wakeup.S
index ead21b663117..b4fd836e4053 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.S
+++ b/arch/x86/kernel/acpi/realmode/wakeup.S
@@ -28,6 +28,8 @@ pmode_cr3: .long 0 /* Saved %cr3 */
pmode_cr4: .long 0 /* Saved %cr4 */
pmode_efer: .quad 0 /* Saved EFER */
pmode_gdt: .quad 0
+pmode_misc_en: .quad 0 /* Saved MISC_ENABLE MSR */
+pmode_behavior: .long 0 /* Wakeup behavior flags */
realmode_flags: .long 0
real_magic: .long 0
trampoline_segment: .word 0
@@ -91,6 +93,18 @@ wakeup_code:
/* Call the C code */
calll main
+ /* Restore MISC_ENABLE before entering protected mode, in case
+ BIOS decided to clear XD_DISABLE during S3. */
+ movl pmode_behavior, %eax
+ btl $WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE, %eax
+ jnc 1f
+
+ movl pmode_misc_en, %eax
+ movl pmode_misc_en + 4, %edx
+ movl $MSR_IA32_MISC_ENABLE, %ecx
+ wrmsr
+1:
+
/* Do any other stuff... */
#ifndef CONFIG_64BIT
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.h b/arch/x86/kernel/acpi/realmode/wakeup.h
index e1828c07e79c..97a29e1430e3 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.h
+++ b/arch/x86/kernel/acpi/realmode/wakeup.h
@@ -21,6 +21,9 @@ struct wakeup_header {
u32 pmode_efer_low; /* Protected mode EFER */
u32 pmode_efer_high;
u64 pmode_gdt;
+ u32 pmode_misc_en_low; /* Protected mode MISC_ENABLE */
+ u32 pmode_misc_en_high;
+ u32 pmode_behavior; /* Wakeup routine behavior flags */
u32 realmode_flags;
u32 real_magic;
u16 trampoline_segment; /* segment with trampoline code, 64-bit only */
@@ -39,4 +42,7 @@ extern struct wakeup_header wakeup_header;
#define WAKEUP_HEADER_SIGNATURE 0x51ee1111
#define WAKEUP_END_SIGNATURE 0x65a22c82
+/* Wakeup behavior bits */
+#define WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE 0
+
#endif /* ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H */
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 18a857ba7a25..103b6ab368d3 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -77,6 +77,12 @@ int acpi_suspend_lowlevel(void)
header->pmode_cr0 = read_cr0();
header->pmode_cr4 = read_cr4_safe();
+ header->pmode_behavior = 0;
+ if (!rdmsr_safe(MSR_IA32_MISC_ENABLE,
+ &header->pmode_misc_en_low,
+ &header->pmode_misc_en_high))
+ header->pmode_behavior |=
+ (1 << WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE);
header->realmode_flags = acpi_realmode_flags;
header->real_magic = 0x12345678;