From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9ED9CC43334 for ; Fri, 22 Jul 2022 09:20:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235808AbiGVJUX (ORCPT ); Fri, 22 Jul 2022 05:20:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236151AbiGVJTY (ORCPT ); Fri, 22 Jul 2022 05:19:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E10D7BB228; Fri, 22 Jul 2022 02:13:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0BD2261F4F; Fri, 22 Jul 2022 09:13:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E208C341C7; Fri, 22 Jul 2022 09:13:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658481211; bh=t9OjSjSmFBOXBMMrmj1viWCftNw3XoVmdHmp2Dv1q/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DuVh9vbQlS9oQXgxtIyg8l8HwXBwJJSeqeMJK8rF6rNQ4PbZXBA1K4zQDjRxvr5rY kO2gB7bKCJjeMsu7sBGGPzatJaV7VbulpscBDsgI3Cg6IxuM2gOoQCXA0quWZ9KT4b GbX0lFL54Jy+huJIhae6f22IoiR8AWJ5wkHIvd7Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Peter Zijlstra (Intel)" , Borislav Petkov , Josh Poimboeuf , Thadeu Lima de Souza Cascardo Subject: [PATCH 5.15 33/89] x86/ftrace: Use alternative RET encoding Date: Fri, 22 Jul 2022 11:11:07 +0200 Message-Id: <20220722091135.217443379@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220722091133.320803732@linuxfoundation.org> References: <20220722091133.320803732@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra commit 1f001e9da6bbf482311e45e48f53c2bd2179e59c upstream. Use the return thunk in ftrace trampolines, if needed. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov [cascardo: still copy return from ftrace_stub] [cascardo: use memcpy(text_gen_insn) as there is no __text_gen_insn] Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/ftrace.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -308,7 +308,7 @@ union ftrace_op_code_union { } __attribute__((packed)); }; -#define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS) +#define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS)) static unsigned long create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) @@ -367,7 +367,10 @@ create_trampoline(struct ftrace_ops *ops /* The trampoline ends with ret(q) */ retq = (unsigned long)ftrace_stub; - ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE); + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) + memcpy(ip, text_gen_insn(JMP32_INSN_OPCODE, ip, &__x86_return_thunk), JMP32_INSN_SIZE); + else + ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE); if (WARN_ON(ret < 0)) goto fail;