linux-kernel - [tip:x86/urgent] x86, suspend: Correct the restore of CR4, EFER; skip computing EFLAGS.ID

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Message-ID: <tip-1396adc3c2bdc556d4cdd1cf107aa0b6d59fbb1e@git.kernel.org>
Date:	Mon, 1 Oct 2012 23:52:45 -0700
From:	"tip-bot for H. Peter Anvin" <hpa@...ux.intel.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	tglx@...utronix.de, rjw@...k.pl, hpa@...ux.intel.com
Subject: [tip:x86/urgent] x86, suspend: Correct the restore of CR4, EFER;
  skip computing EFLAGS.ID

Commit-ID:  1396adc3c2bdc556d4cdd1cf107aa0b6d59fbb1e
Gitweb:     http://git.kernel.org/tip/1396adc3c2bdc556d4cdd1cf107aa0b6d59fbb1e
Author:     H. Peter Anvin <hpa@...ux.intel.com>
AuthorDate: Mon, 1 Oct 2012 14:34:42 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 2 Oct 2012 08:42:31 +0200

x86, suspend: Correct the restore of CR4, EFER; skip computing EFLAGS.ID

The patch:

    73201dbe x86, suspend: On wakeup always initialize cr4 and EFER

... was incorrectly committed in an intermediate (unfinished) form.

- We need to test CF, not ZF, for a bit test with btl.
- We don't actually need to compute the existence of EFLAGS.ID,
  since we set a flag at suspend time if CR4 should be restored.

Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Cc: Rafael J. Wysocki <rjw@...k.pl>
Link: http://lkml.kernel.org/r/1348529239-17943-1-git-send-email-hpa@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/realmode/rm/wakeup_asm.S |   15 +++------------
 1 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/arch/x86/realmode/rm/wakeup_asm.S b/arch/x86/realmode/rm/wakeup_asm.S
index e56479e..9e7e147 100644
--- a/arch/x86/realmode/rm/wakeup_asm.S
+++ b/arch/x86/realmode/rm/wakeup_asm.S
@@ -74,18 +74,9 @@ ENTRY(wakeup_start)
 
 	lidtl	wakeup_idt
 
-	/* Clear the EFLAGS but remember if we have EFLAGS.ID */
-	movl $X86_EFLAGS_ID, %ecx
-	pushl %ecx
-	popfl
-	pushfl
-	popl %edi
+	/* Clear the EFLAGS */
 	pushl $0
 	popfl
-	pushfl
-	popl %edx
-	xorl %edx, %edi
-	andl %ecx, %edi		/* %edi is zero iff CPUID & %cr4 are missing */
 
 	/* Check header signature... */
 	movl	signature, %eax
@@ -120,12 +111,12 @@ ENTRY(wakeup_start)
 	movl	%eax, %cr3
 
 	btl	$WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
-	jz	1f
+	jnc	1f
 	movl	pmode_cr4, %eax
 	movl	%eax, %cr4
 1:
 	btl	$WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
-	jz	1f
+	jnc	1f
 	movl	pmode_efer, %eax
 	movl	pmode_efer + 4, %edx
 	movl	$MSR_EFER, %ecx
--
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