x86, suspend: On wakeup always initialize cr4 and EFER

We already have a flag word to indicate the existence of MISC_ENABLES,
so use the same flag word to indicate existence of cr4 and EFER, and
always restore them if they exist.  That way if something passes a
nonzero value when the value *should* be zero, we will still
initialize it.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Link: http://lkml.kernel.org/r/1348529239-17943-1-git-send-email-hpa@linux.intel.com

2 files changed, 21 insertions, 10 deletions

diff --git a/arch/x86/realmode/rm/wakeup.h b/arch/x86/realmode/rm/wakeup.h
index 9317e0042f24..7dd86a419f5d 100644
--- a/arch/x86/realmode/rm/wakeup.h
+++ b/arch/x86/realmode/rm/wakeup.h
@@ -36,5 +36,7 @@ extern struct wakeup_header wakeup_header;
 
 /* Wakeup behavior bits */
 #define WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE     0
+#define WAKEUP_BEHAVIOR_RESTORE_CR4             1
+#define WAKEUP_BEHAVIOR_RESTORE_EFER            2
 
 #endif /* ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H */
diff --git a/arch/x86/realmode/rm/wakeup_asm.S b/arch/x86/realmode/rm/wakeup_asm.S
index 8905166b0bbb..e56479e58053 100644
--- a/arch/x86/realmode/rm/wakeup_asm.S
+++ b/arch/x86/realmode/rm/wakeup_asm.S
@@ -74,9 +74,18 @@ ENTRY(wakeup_start)
 
         lidtl   wakeup_idt
 
-        /* Clear the EFLAGS */
-        pushl   $0
+        /* Clear the EFLAGS but remember if we have EFLAGS.ID */
+        movl $X86_EFLAGS_ID, %ecx
+        pushl %ecx
         popfl
+        pushfl
+        popl %edi
+        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
@@ -93,8 +102,8 @@ ENTRY(wakeup_start)
 
         /* 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
+        movl    pmode_behavior, %edi
+        btl     $WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE, %edi
         jnc     1f
 
         movl    pmode_misc_en, %eax
@@ -110,15 +119,15 @@ ENTRY(wakeup_start)
         movl    pmode_cr3, %eax
         movl    %eax, %cr3
 
-        movl    pmode_cr4, %ecx
-        jecxz   1f
-        movl    %ecx, %cr4
+        btl     $WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
+        jz      1f
+        movl    pmode_cr4, %eax
+        movl    %eax, %cr4
 1:
+        btl     $WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
+        jz      1f
         movl    pmode_efer, %eax
         movl    pmode_efer + 4, %edx
-        movl    %eax, %ecx
-        orl     %edx, %ecx
-        jz      1f
         movl    $MSR_EFER, %ecx
         wrmsr
 1: