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x86, sleep: Always save the value of EFER

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Always save the value of EFER, regardless of the state of NX.  Since
EFER may not actually exist, use rdmsr_safe() to do so.

v2: check the return value from rdmsr_safe() instead of relying on
    the output values being unchanged on error.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@tuxonice.net>
LKML-Reference: <1258154897-6770-3-git-send-email-hpa@zytor.com>
Acked-by: Kees Cook <kees.cook@canonical.com>
This commit is contained in:
H. Peter Anvin 2009-11-13 15:28:14 -08:00
parent 8a50e5135a
commit a7c4c0d934
1 changed files with 3 additions and 6 deletions
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9
arch/x86/kernel/acpi/sleep.c
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@ -78,12 +78,9 @@ int acpi_save_state_mem(void)
#ifndef CONFIG_64BIT
store_gdt((struct desc_ptr *)&header->pmode_gdt);
header->pmode_efer_low = nx_enabled;
if (header->pmode_efer_low & 1) {
/* This is strange, why not save efer, always? */
rdmsr(MSR_EFER, header->pmode_efer_low,
header->pmode_efer_high);
}
if (rdmsr_safe(MSR_EFER, &header->pmode_efer_low,
&header->pmode_efer_high))
header->pmode_efer_low = header->pmode_efer_high = 0;
#endif /* !CONFIG_64BIT */
header->pmode_cr0 = read_cr0();