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 22FDDC43334 for ; Sat, 23 Jul 2022 10:07:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238709AbiGWKHW (ORCPT ); Sat, 23 Jul 2022 06:07:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58822 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238475AbiGWKGy (ORCPT ); Sat, 23 Jul 2022 06:06:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFED377546; Sat, 23 Jul 2022 03:01:06 -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 ams.source.kernel.org (Postfix) with ESMTPS id 027F4B82C21; Sat, 23 Jul 2022 10:00:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B7B9C341C0; Sat, 23 Jul 2022 10:00:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658570444; bh=QtnsdZLxc5e//iy3s2gLvf5/wn1Pnwcij+P+Wg6G5ag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1ZYzrpfZRDLnwLz4epgHmUuqyEgbtu4ecHLrb4yrSdUKT47jOnJwwKmKgQYKNNV5M wjXujk19fAEiaQo8C5T5fMh2YD+mRLEaeTnUpjmFf9yVRLaqg4xfzimMq5DGWQxe/I 3+rSyFapyoYVHUB+sPKzz2yKjJYZmz9aB4VzJQcE= 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 , Ben Hutchings Subject: [PATCH 5.10 089/148] x86/bpf: Use alternative RET encoding Date: Sat, 23 Jul 2022 11:55:01 +0200 Message-Id: <20220723095249.358079262@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220723095224.302504400@linuxfoundation.org> References: <20220723095224.302504400@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 d77cfe594ad50e0bf95d457e02ccd578791b2a15 upstream. Use the return thunk in eBPF generated code, if needed. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo [bwh: Backported to 5.10: add the necessary cnt variable to emit_return()] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/net/bpf_jit_comp.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -399,6 +399,22 @@ static void emit_indirect_jump(u8 **ppro *pprog = prog; } +static void emit_return(u8 **pprog, u8 *ip) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) { + emit_jump(&prog, &__x86_return_thunk, ip); + } else { + EMIT1(0xC3); /* ret */ + if (IS_ENABLED(CONFIG_SLS)) + EMIT1(0xCC); /* int3 */ + } + + *pprog = prog; +} + /* * Generate the following code: * @@ -1443,7 +1459,7 @@ emit_jmp: ctx->cleanup_addr = proglen; pop_callee_regs(&prog, callee_regs_used); EMIT1(0xC9); /* leave */ - EMIT1(0xC3); /* ret */ + emit_return(&prog, image + addrs[i - 1] + (prog - temp)); break; default: @@ -1884,7 +1900,7 @@ int arch_prepare_bpf_trampoline(struct b if (flags & BPF_TRAMP_F_SKIP_FRAME) /* skip our return address and return to parent */ EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */ - EMIT1(0xC3); /* ret */ + emit_return(&prog, prog); /* Make sure the trampoline generation logic doesn't overflow */ if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) { ret = -EFAULT;