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 5952AC433EF for ; Tue, 12 Jul 2022 19:08:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235584AbiGLTIo (ORCPT ); Tue, 12 Jul 2022 15:08:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235550AbiGLTHz (ORCPT ); Tue, 12 Jul 2022 15:07:55 -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 BEC42E43D1; Tue, 12 Jul 2022 11:51:41 -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 A94B861491; Tue, 12 Jul 2022 18:51:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF782C3411C; Tue, 12 Jul 2022 18:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657651898; bh=MXrrOTrkk/RGgoaIHAExHDTa3cUXx3Dyxn8DhpPAaWI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ipHmrddWCTTacHSmkOtwR8SWm0lTgdBIuXm30dvmK9RMy/wYCpWtkfA/DMz0CXz5v xT2CVwaM7cE8hB0n/zE53IQIRdl7NJotz6L2u2x5ZZnqzZHstSoVO5BCAkHydoDOzQ FqL3VogMvwe6jqMYw1ZEcinhU+q/jsC7es+K3qsw= 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 5.18 16/61] x86/bpf: Use alternative RET encoding Date: Tue, 12 Jul 2022 20:39:13 +0200 Message-Id: <20220712183237.596015580@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220712183236.931648980@linuxfoundation.org> References: <20220712183236.931648980@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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/net/bpf_jit_comp.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -420,6 +420,21 @@ static void emit_indirect_jump(u8 **ppro *pprog = prog; } +static void emit_return(u8 **pprog, u8 *ip) +{ + u8 *prog = *pprog; + + 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: * @@ -1680,7 +1695,7 @@ 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: @@ -2157,7 +2172,7 @@ 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;