Commit b2f4d82a authored Oct 07, 2023 by Peter Zijlstra Committed by Jialin Zhang Oct 12, 2023

objtool/x86: Fixup frame-pointer vs rethunk

stable inclusion
from stable-v5.10.192
commit 23e59874657c6396abb82544f6f60d100d84ee6a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=23e59874657c6396abb82544f6f60d100d84ee6a



--------------------------------

commit dbf46008 upstream.

For stack-validation of a frame-pointer build, objtool validates that
every CALL instruction is preceded by a frame-setup. The new SRSO
return thunks violate this with their RSB stuffing trickery.

Extend the __fentry__ exception to also cover the embedded_insn case
used for this. This cures:

  vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup

Fixes: 4ae68b26 ("objtool/x86: Fix SRSO mess")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>

parent 870d257c

tools/objtool/check.c

+11 −6

Original line number	Diff line number	Diff line
		@@ -2078,12 +2078,17 @@ static int decode_sections(struct objtool_file *file)
		return 0;
		}

		static bool is_fentry_call(struct instruction *insn)
		static bool is_special_call(struct instruction *insn)
		{
		if (insn->type == INSN_CALL &&
		insn->call_dest &&
		insn->call_dest->fentry)
		if (insn->type == INSN_CALL) {
		struct symbol *dest = insn->call_dest;

		if (!dest)
		return false;

		if (dest->fentry)
		return true;
		}

		return false;
		}
		@@ -2957,7 +2962,7 @@ static int validate_branch(struct objtool_file file, struct symbol func,
		if (ret)
		return ret;

		if (!no_fp && func && !is_fentry_call(insn) &&
		if (!no_fp && func && !is_special_call(insn) &&
		!has_valid_stack_frame(&state)) {
		WARN_FUNC("call without frame pointer save/setup",
		sec, insn->offset);