diff options
| author | Borislav Petkov <bp@suse.de> | 2015-11-05 16:57:56 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2015-11-07 10:45:02 +0100 |
| commit | 04633df0c43d710e5f696b06539c100898678235 (patch) | |
| tree | f89040bf51f76c386da00dd8a18312c5bf959d70 /arch/x86/kernel/head_64.S | |
| parent | 68accac392d859d24adcf1be3a90e41f978bd54c (diff) | |
x86/cpu: Call verify_cpu() after having entered long mode too
When we get loaded by a 64-bit bootloader, kernel entry point is
startup_64 in head_64.S. We don't trust any and all bootloaders because
some will fiddle with CPU configuration so we go ahead and massage each
CPU into sanity again.
For example, some dell BIOSes have this XD disable feature which set
IA32_MISC_ENABLE[34] and disable NX. This might be some dumb workaround
for other OSes but Linux sure doesn't need it.
A similar thing is present in the Surface 3 firmware - see
https://bugzilla.kernel.org/show_bug.cgi?id=106051 - which sets this bit
only on the BSP:
# rdmsr -a 0x1a0
400850089
850089
850089
850089
I know, right?!
There's not even an off switch in there.
So fix all those cases by sanitizing the 64-bit entry point too. For
that, make verify_cpu() callable in 64-bit mode also.
Requested-and-debugged-by: "H. Peter Anvin" <hpa@zytor.com>
Reported-and-tested-by: Bastien Nocera <bugzilla@hadess.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1446739076-21303-1-git-send-email-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/head_64.S')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 1d40ca8a73f2..ffdc0e860390 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -65,6 +65,9 @@ startup_64: * tables and then reload them. */ + /* Sanitize CPU configuration */ + call verify_cpu + /* * Compute the delta between the address I am compiled to run at and the * address I am actually running at. @@ -174,6 +177,9 @@ ENTRY(secondary_startup_64) * after the boot processor executes this code. */ + /* Sanitize CPU configuration */ + call verify_cpu + movq $(init_level4_pgt - __START_KERNEL_map), %rax 1: @@ -288,6 +294,8 @@ ENTRY(secondary_startup_64) pushq %rax # target address in negative space lretq +#include "verify_cpu.S" + #ifdef CONFIG_HOTPLUG_CPU /* * Boot CPU0 entry point. It's called from play_dead(). Everything has been set |