From 7a3136666bc0f0419f7aaa7b1fabb4b0e0a7fb76 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 6 Jul 2011 18:10:34 -0700 Subject: [PATCH] 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 Link: http://lkml.kernel.org/r/20110707011034.GA8523@outflux.net Signed-off-by: H. Peter Anvin Cc: Rafael J. Wysocki Cc: 2.6.38+ --- 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(+) 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; -- 2.20.1