[PATCH 0/2] x86: restore MISC_ENABLE MSR in realmode wakeup

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* [PATCH 0/2] x86: restore MISC_ENABLE MSR in realmode wakeup
@ 2011-07-04 22:35 Kees Cook
  2011-07-04 22:35 ` [PATCH 1/2] x86: give names to realmode wakeup flags Kees Cook
  2011-07-04 22:35 ` [PATCH 2/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook
  0 siblings, 2 replies; 6+ messages in thread
From: Kees Cook @ 2011-07-04 22:35 UTC (permalink / raw)
  To: x86, linux-kernel
  Cc: Len Brown, Pavel Machek, Rafael J. Wysocki, Thomas Gleixner,
	Ingo Molnar, H. Peter Anvin

This is a different approach to handle the situation discussed in
https://lkml.org/lkml/2011/7/1/404, this time restoring the entire
MISC_ENABLE MSR.

-Kees

-- 
Kees Cook
Ubuntu Security Team


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 1/2] x86: give names to realmode wakeup flags
  2011-07-04 22:35 [PATCH 0/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook
@ 2011-07-04 22:35 ` Kees Cook
  2011-07-05 22:39   ` H. Peter Anvin
  2011-07-04 22:35 ` [PATCH 2/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook
  1 sibling, 1 reply; 6+ messages in thread
From: Kees Cook @ 2011-07-04 22:35 UTC (permalink / raw)
  To: x86, linux-kernel
  Cc: Len Brown, Pavel Machek, Rafael J. Wysocki, Thomas Gleixner,
	Ingo Molnar, H. Peter Anvin

Instead of using literals, use a common set of names for the
user-controlled realmode wakeup flags.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
---
 arch/x86/kernel/acpi/realmode/wakemain.c |    6 +++---
 arch/x86/kernel/acpi/realmode/wakeup.h   |    4 ++++
 arch/x86/kernel/acpi/sleep.c             |    6 +++---
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/acpi/realmode/wakemain.c b/arch/x86/kernel/acpi/realmode/wakemain.c
index 883962d..1749cde 100644
--- a/arch/x86/kernel/acpi/realmode/wakemain.c
+++ b/arch/x86/kernel/acpi/realmode/wakemain.c
@@ -67,13 +67,13 @@ void main(void)
 	if (wakeup_header.real_magic != 0x12345678)
 		while (1);
 
-	if (wakeup_header.realmode_flags & 4)
+	if (wakeup_header.realmode_flags & WAKE_FLAG_BEEP)
 		send_morse("...-");
 
-	if (wakeup_header.realmode_flags & 1)
+	if (wakeup_header.realmode_flags & WAKE_FLAG_BIOS)
 		asm volatile("lcallw   $0xc000,$3");
 
-	if (wakeup_header.realmode_flags & 2) {
+	if (wakeup_header.realmode_flags & WAKE_FLAG_MODE) {
 		/* Need to call BIOS */
 		probe_cards(0);
 		set_mode(wakeup_header.video_mode);
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.h b/arch/x86/kernel/acpi/realmode/wakeup.h
index e1828c0..88f0e6c 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.h
+++ b/arch/x86/kernel/acpi/realmode/wakeup.h
@@ -39,4 +39,8 @@ extern struct wakeup_header wakeup_header;
 #define WAKEUP_HEADER_SIGNATURE 0x51ee1111
 #define WAKEUP_END_SIGNATURE	0x65a22c82
 
+#define WAKEUP_FLAG_BIOS        1
+#define WAKEUP_FLAG_MODE        2
+#define WAKEUP_FLAG_BEEP        4
+
 #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 18a857b..cb968e5 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -104,11 +104,11 @@ static int __init acpi_sleep_setup(char *str)
 {
 	while ((str != NULL) && (*str != '\0')) {
 		if (strncmp(str, "s3_bios", 7) == 0)
-			acpi_realmode_flags |= 1;
+			acpi_realmode_flags |= WAKEUP_FLAG_BIOS;
 		if (strncmp(str, "s3_mode", 7) == 0)
-			acpi_realmode_flags |= 2;
+			acpi_realmode_flags |= WAKEUP_FLAG_MODE;
 		if (strncmp(str, "s3_beep", 7) == 0)
-			acpi_realmode_flags |= 4;
+			acpi_realmode_flags |= WAKEUP_FLAG_BEEP;
 #ifdef CONFIG_HIBERNATION
 		if (strncmp(str, "s4_nohwsig", 10) == 0)
 			acpi_no_s4_hw_signature();
-- 
1.7.4.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH 1/2] x86: give names to realmode wakeup flags
  2011-07-04 22:35 ` [PATCH 1/2] x86: give names to realmode wakeup flags Kees Cook
@ 2011-07-05 22:39   ` H. Peter Anvin
  2011-07-06  1:27     ` Kees Cook
  0 siblings, 1 reply; 6+ messages in thread
From: H. Peter Anvin @ 2011-07-05 22:39 UTC (permalink / raw)
  To: Kees Cook
  Cc: x86, linux-kernel, Len Brown, Pavel Machek, Rafael J. Wysocki,
	Thomas Gleixner, Ingo Molnar

On 07/04/2011 03:35 PM, Kees Cook wrote:
> Instead of using literals, use a common set of names for the
> user-controlled realmode wakeup flags.
> 
> Signed-off-by: Kees Cook <kees.cook@canonical.com>

I'm sorry, but I really have to complain about this:

This was a very unfriendly thing to do.  You took a patch that is a bug
fix to be considered for -stable, and you applied it *on top of a
cleanup patch*.  They should not have been part of the same patchset,
but *certainly* not in that order.

Please resubmit.

	-hpa

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH 1/2] x86: give names to realmode wakeup flags
  2011-07-05 22:39   ` H. Peter Anvin
@ 2011-07-06  1:27     ` Kees Cook
  2011-07-06  2:41       ` H. Peter Anvin
  0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2011-07-06  1:27 UTC (permalink / raw)
  To: H. Peter Anvin
  Cc: x86, linux-kernel, Len Brown, Pavel Machek, Rafael J. Wysocki,
	Thomas Gleixner, Ingo Molnar

On Tue, Jul 05, 2011 at 03:39:54PM -0700, H. Peter Anvin wrote:
> On 07/04/2011 03:35 PM, Kees Cook wrote:
> > Instead of using literals, use a common set of names for the
> > user-controlled realmode wakeup flags.
> > 
> > Signed-off-by: Kees Cook <kees.cook@canonical.com>
> 
> I'm sorry, but I really have to complain about this:
> 
> This was a very unfriendly thing to do.

Obviously I wasn't trying to be unfriendly. :P

> You took a patch that is a bug fix to be considered for -stable,
> and you applied it *on top of a cleanup patch*.

It wasn't clear to me if the MISC_ENABLE reload should be considered for
stable (it does technically "more" than my original patch, and changes
the resume header structure, etc). If it should be forwarded to -stable,
that's fine too. I just didn't want to presume.

> They should not have been part of the same patchset,
> but *certainly* not in that order.

Since they hit the same .h file in the same location, I wasn't sure what
order to do it in. It seemed unhelpful to send them separately.

> Please resubmit.

Sure thing -- in the opposite order, or totally separate from each other?

-Kees

-- 
Kees Cook
Ubuntu Security Team

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH 1/2] x86: give names to realmode wakeup flags
  2011-07-06  1:27     ` Kees Cook
@ 2011-07-06  2:41       ` H. Peter Anvin
  0 siblings, 0 replies; 6+ messages in thread
From: H. Peter Anvin @ 2011-07-06  2:41 UTC (permalink / raw)
  To: Kees Cook
  Cc: x86, linux-kernel, Len Brown, Pavel Machek, Rafael J. Wysocki,
	Thomas Gleixner, Ingo Molnar

On 07/05/2011 06:27 PM, Kees Cook wrote:
> 
>> Please resubmit.
> 
> Sure thing -- in the opposite order, or totally separate from each other?
> 

Either is fine.

	-hpa


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 2/2] x86: restore MISC_ENABLE MSR in realmode wakeup
  2011-07-04 22:35 [PATCH 0/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook
  2011-07-04 22:35 ` [PATCH 1/2] x86: give names to realmode wakeup flags Kees Cook
@ 2011-07-04 22:35 ` Kees Cook
  1 sibling, 0 replies; 6+ messages in thread
From: Kees Cook @ 2011-07-04 22:35 UTC (permalink / raw)
  To: x86, linux-kernel
  Cc: Len Brown, Pavel Machek, Rafael J. Wysocki, Thomas Gleixner,
	Ingo Molnar, H. Peter Anvin

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.)

Signed-off-by: Kees Cook <kees.cook@canonical.com>
---
 arch/x86/kernel/acpi/realmode/wakeup.S |   14 ++++++++++++++
 arch/x86/kernel/acpi/realmode/wakeup.h |    6 ++++++
 arch/x86/kernel/acpi/sleep.c           |    6 ++++++
 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 ead21b6..b4fd836 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 88f0e6c..5487db0 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 */
@@ -43,4 +46,7 @@ extern struct wakeup_header wakeup_header;
 #define WAKEUP_FLAG_MODE        2
 #define WAKEUP_FLAG_BEEP        4
 
+/* 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 cb968e5..12115a9 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;
 
-- 
1.7.4.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2011-07-06  2:42 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-07-04 22:35 [PATCH 0/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook
2011-07-04 22:35 ` [PATCH 1/2] x86: give names to realmode wakeup flags Kees Cook
2011-07-05 22:39   ` H. Peter Anvin
2011-07-06  1:27     ` Kees Cook
2011-07-06  2:41       ` H. Peter Anvin
2011-07-04 22:35 ` [PATCH 2/2] x86: restore MISC_ENABLE MSR in realmode wakeup Kees Cook

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