Commit 9bb2ec60 authored Jun 14, 2022 by Peter Zijlstra Committed by Borislav Petkov Jun 27, 2022

objtool: Update Retpoline validation



Update retpoline validation with the new CONFIG_RETPOLINE requirement of
not having bare naked RET instructions.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>

parent bf5835bc

arch/x86/include/asm/nospec-branch.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -75,6 +75,12 @@
		.popsection
		.endm

		/*
		* (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions
		* vs RETBleed validation.
		*/
		#define ANNOTATE_UNRET_SAFE ANNOTATE_RETPOLINE_SAFE

		/*
		* JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple
		* indirect jmp/call which may be susceptible to the Spectre variant 2

arch/x86/mm/mem_encrypt_boot.S

+2 −0

Original line number	Diff line number	Diff line
		@@ -66,6 +66,7 @@ SYM_FUNC_START(sme_encrypt_execute)
		pop %rbp

		/* Offset to __x86_return_thunk would be wrong here */
		ANNOTATE_UNRET_SAFE
		ret
		int3
		SYM_FUNC_END(sme_encrypt_execute)
		@@ -154,6 +155,7 @@ SYM_FUNC_START(__enc_copy)
		pop %r15

		/* Offset to __x86_return_thunk would be wrong here */
		ANNOTATE_UNRET_SAFE
		ret
		int3
		.L__enc_copy_end:

arch/x86/xen/xen-head.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ SYM_CODE_START(hypercall_page)
		.rept (PAGE_SIZE / 32)
		UNWIND_HINT_FUNC
		ANNOTATE_NOENDBR
		ANNOTATE_UNRET_SAFE
		ret
		/*
		* Xen will write the hypercall page, and sort out ENDBR.

tools/objtool/check.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -2115,8 +2115,9 @@ static int read_retpoline_hints(struct objtool_file *file)
		}

		if (insn->type != INSN_JUMP_DYNAMIC &&
		insn->type != INSN_CALL_DYNAMIC) {
		WARN_FUNC("retpoline_safe hint not an indirect jump/call",
		insn->type != INSN_CALL_DYNAMIC &&
		insn->type != INSN_RETURN) {
		WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret",
		insn->sec, insn->offset);
		return -1;
		}
		@@ -3526,7 +3527,8 @@ static int validate_retpoline(struct objtool_file *file)

		for_each_insn(file, insn) {
		if (insn->type != INSN_JUMP_DYNAMIC &&
		insn->type != INSN_CALL_DYNAMIC)
		insn->type != INSN_CALL_DYNAMIC &&
		insn->type != INSN_RETURN)
		continue;

		if (insn->retpoline_safe)
		@@ -3541,9 +3543,14 @@ static int validate_retpoline(struct objtool_file *file)
		if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
		continue;

		if (insn->type == INSN_RETURN) {
		WARN_FUNC("'naked' return found in RETPOLINE build",
		insn->sec, insn->offset);
		} else {
		WARN_FUNC("indirect %s found in RETPOLINE build",
		insn->sec, insn->offset,
		insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
		}

		warnings++;
		}