Commit f6a2c2b2 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Peter Zijlstra
Browse files

x86/Kconfig: Only allow CONFIG_X86_KERNEL_IBT with ld.lld >= 14.0.0 



With CONFIG_X86_KERNEL_IBT=y and a version of ld.lld prior to 14.0.0,
there are numerous objtool warnings along the lines of:

  warning: objtool: .plt+0x6: indirect jump found in RETPOLINE build

This is a known issue that has been resolved in ld.lld 14.0.0. Prevent
CONFIG_X86_KERNEL_IBT from being selectable when using one of these
problematic ld.lld versions.

Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220318230747.3900772-3-nathan@kernel.org
parent 262448f3

arch/x86/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -1875,6 +1875,8 @@ config X86_KERNEL_IBT 
	prompt "Indirect Branch Tracking"

	bool

	depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION

	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f

	depends on !LD_IS_LLD || LLD_VERSION >= 140000

	help

	  Build the kernel with support for Indirect Branch Tracking, a

	  hardware support course-grain forward-edge Control Flow Integrity