On 2022-10-19 10:57, Andrew Cooper wrote:
On 06/09/2022 11:41, Evgeniy Baskov wrote:
diff --git a/arch/x86/boot/compressed/head_64.S
b/arch/x86/boot/compressed/head_64.S
index 5273367283b7..889ca7176aa7 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -602,6 +603,28 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
jmp *%rax
SYM_FUNC_END(.Lrelocated)
+SYM_FUNC_START_LOCAL_NOALIGN(startup32_enable_nx_if_supported)
+ pushq %rbx
+
+ leaq has_nx(%rip), %rcx
+
+ mov $0x80000001, %eax
+ cpuid
+ btl $20, %edx
btl $(X86_FEATURE_NX & 31), %edx
But also need to check for the availability of the extended leaf in the
first place.
Yes, thank you for suggestion, that looks more readable. I will
also add the leaf node check. Is there any processor though that
supports long mode and does not support 0x80000001 leaf node?
+ jnc .Lnonx
+
+ movl $1, (%rcx)
Your pointer has been clobbered with some feature flags.
Thanks, I apparently forgot to include fix for this into a patch set...
movl $1, has_nx(%rip)
will work fine without needing the intermediary lea.
~Andrew
