From patchwork Tue Nov 22 11:12:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13052222 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 28CC9C4332F for ; Tue, 22 Nov 2022 11:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233207AbiKVLSd (ORCPT ); Tue, 22 Nov 2022 06:18:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232704AbiKVLRc (ORCPT ); Tue, 22 Nov 2022 06:17:32 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD994E094; Tue, 22 Nov 2022 03:14:46 -0800 (PST) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id DDAB640737BC; Tue, 22 Nov 2022 11:14:44 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru DDAB640737BC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1669115685; bh=ECseb6siPLZccH2FNtVbbnERJUQobRq291fpKz8aIww=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VPiJwsYdfgZtNzI/9Q3y26cnwCKwOz8T5jNsOKhxqG+V8x4LYrDU0adtar4OlsOgy qRD5XGs0+z9uv6irj0VH1T6YWpybVM3LpujcnTpu9536RR6LfSdSJG5SMCNkTl2MP3 EEXskEdyftMKZmSQZKHsKg6uYn0VPF+yQTVlZ6no= 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 , "Limonciello, Mario" , joeyli , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3 17/24] x86/boot: Reduce size of the DOS stub Date: Tue, 22 Nov 2022 14:12:26 +0300 Message-Id: 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. Tested-by: Mario Limonciello 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: