Re: [RFC PATCH v9 05/27] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack protection
From: Dave Hansen <hidden>
Date: 2020-02-26 18:05:54
Also in:
linux-arch, linux-doc, linux-mm, lkml
On 2/5/20 10:19 AM, Yu-cheng Yu wrote:
+# Check assembler Shadow Stack suppot
^ support
+ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + ifeq ($(call as-instr, saveprevssp, y),) + $(error CONFIG_X86_INTEL_SHADOW_STACK_USER not supported by the assembler) + endif +endif
Is this *just* looking for instruction support in the assembler?
We usually just .byte them, like this for pkeys:
asm volatile(".byte 0x0f,0x01,0xee\n\t"
: "=a" (pkru), "=d" (edx)
: "c" (ecx));
That way everybody with old toolchains can still build the kernel (and
run/test code with your config option on, btw...).