From patchwork Tue Oct 25 14:12:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13019339 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 C3284FA3741 for ; Tue, 25 Oct 2022 14:14:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233181AbiJYOOY (ORCPT ); Tue, 25 Oct 2022 10:14:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233169AbiJYOOH (ORCPT ); Tue, 25 Oct 2022 10:14:07 -0400 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D53319B87D; Tue, 25 Oct 2022 07:14:05 -0700 (PDT) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id 5343E40737B7; Tue, 25 Oct 2022 14:14:04 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 5343E40737B7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1666707244; bh=HI18v3+f+Pl+YyhFoHiqU9HpwMvARvOP6MXeGpCdq1M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K4Rw76ioj0sV5FcOz4mFluQTJQFBRHderUB+3PtsfLmRUHykCd4zoE9DfD/zWpjE3 ZOD/8mpLuAe1pKFxE3UIxKT2VlzdDmT5d8b6HLPV0CStVtl8WyzdGzze4zFxXDCdTk 4TQzY3EtG8UnXVDdOWdsLI/Nr/0hBx406Ov2CwVA= From: Evgeniy Baskov To: Ard Biesheuvel Cc: Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 17/23] x86/boot: Reduce size of the DOS stub Date: Tue, 25 Oct 2022 17:12:55 +0300 Message-Id: <2edb38e355437b1946e7fedcd4f5b4857a24be84.1666705333.git.baskov@ispras.ru> X-Mailer: git-send-email 2.37.4 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org This is required to fit more sections in PE section tables, since its size is restricted by zero page located at specific offset after the PE header. Signed-off-by: Evgeniy Baskov --- arch/x86/boot/header.S | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index f912d7770130..e4de831b2f64 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -59,17 +59,16 @@ start2: cld movw $bugger_off_msg, %si + movw $bugger_off_msg_size, %cx msg_loop: lodsb - andb %al, %al - jz bs_die movb $0xe, %ah movw $7, %bx int $0x10 - jmp msg_loop + decw %cx + jnz msg_loop -bs_die: # Allow the user to press a key, then reboot xorw %ax, %ax int $0x16 @@ -89,10 +88,9 @@ bs_die: .section ".bsdata", "a" bugger_off_msg: - .ascii "Use a boot loader.\r\n" - .ascii "\n" - .ascii "Remove disk and press any key to reboot...\r\n" - .byte 0 + .ascii "Use a boot loader. " + .ascii "Press a key to reboot" + .set bugger_off_msg_size, . - bugger_off_msg #ifdef CONFIG_EFI_STUB pe_header: