From patchwork Mon May 8 07:03:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 680037 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 41394C77B73 for ; Mon, 8 May 2023 07:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232011AbjEHHD7 (ORCPT ); Mon, 8 May 2023 03:03:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232428AbjEHHDz (ORCPT ); Mon, 8 May 2023 03:03:55 -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 E7F951A112; Mon, 8 May 2023 00:03:53 -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 7BF4561F8C; Mon, 8 May 2023 07:03:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24313C4339E; Mon, 8 May 2023 07:03:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683529432; bh=UygRvsEzWeCdWneVvfD1K/VpCrMByhROcGCs3aNJ6SY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lpAxgN8jqzCo90JQr6MwZgUoWPmP3Kg/6DHBmLJLkpYmcJWqdRuCM2wcnmZ5RXMqG YE1Rr3N4tB85eff+lpdEJ3a8IKboGiKb1YoxKXFNbMHTCAHrzkoLr6IEpPHy5+s5Tq DTE5JB6xe/KTeqWQ70Km+Zo/QgdBWRq7OzRu9RYpsXvBCAagRq5jXtA1uBJO1g9/hY P32HfVkZLM89fFmDcjcwSGOSXoMjGT3OyBa86VrYSkChJ5lh/vxndlbWkkGXWJkhOx Y5WcKS3wYKlZQ5u0QLfr0R8C2UCAd3U03xKcCyItmw/c5meBsZJHCZuIJ0TUZiqIHL U/5K6vt3TFGvw== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , Gerd Hoffmann , Dave Young , Mario Limonciello , Kees Cook , Tom Lendacky , "Kirill A . Shutemov" , Linus Torvalds Subject: [PATCH v2 03/20] x86: decompressor: Call trampoline as a normal function Date: Mon, 8 May 2023 09:03:13 +0200 Message-Id: <20230508070330.582131-4-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230508070330.582131-1-ardb@kernel.org> References: <20230508070330.582131-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2486; i=ardb@kernel.org; h=from:subject; bh=UygRvsEzWeCdWneVvfD1K/VpCrMByhROcGCs3aNJ6SY=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JISVi3hqjT1yTvBb/VbE9LOGpfbNW9DJD75bcqO0rryvO/ eMgefN0RykLgxgHg6yYIovA7L/vdp6eKFXrPEsWZg4rE8gQBi5OAZjIF1dGhvaPc3t2PrXfzBmQ o1u2Uu6YSaVGdOzq80v21i9d+PyBXDIjw5UvBi5rpYt5My4cyfjMHXNZ4sAJh19SxU6cKoZz0z9 1MgEA X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Move the long return to switch to 32-bit mode into the trampoline code so we can call it as an ordinary function. This will allow us to call it directly from C code in a subsequent patch. Signed-off-by: Ard Biesheuvel Acked-by: Kirill A. Shutemov --- arch/x86/boot/compressed/head_64.S | 25 +++++++++----------- arch/x86/boot/compressed/pgtable.h | 2 +- 2 files changed, 12 insertions(+), 15 deletions(-) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 59340e533dff8369..81b53b576cdd05ae 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -457,18 +457,9 @@ SYM_CODE_START(startup_64) /* Save the trampoline address in RCX */ movq %rax, %rcx - /* - * Load the address of trampoline_return() into RDI. - * It will be used by the trampoline to return to the main code. - */ - leaq trampoline_return(%rip), %rdi - - /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ - pushq $__KERNEL32_CS leaq TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax - pushq %rax - lretq -trampoline_return: + call *%rax + /* Restore the stack, the 32-bit trampoline uses its own stack */ leaq rva(boot_stack_end)(%rbx), %rsp @@ -566,16 +557,22 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) jmp *%rax SYM_FUNC_END(.Lrelocated) - .code32 /* * This is the 32-bit trampoline that will be copied over to low memory. * - * RDI contains the return address (might be above 4G). * ECX contains the base address of the trampoline memory. * Non zero RDX means trampoline needs to enable 5-level paging. */ SYM_CODE_START(trampoline_32bit_src) - /* Set up data and stack segments */ + popq %rdi + /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ + pushq $__KERNEL32_CS + leaq 0f(%rip), %rax + pushq %rax + lretq + + .code32 +0: /* Set up data and stack segments */ movl $__KERNEL_DS, %eax movl %eax, %ds movl %eax, %ss diff --git a/arch/x86/boot/compressed/pgtable.h b/arch/x86/boot/compressed/pgtable.h index cc9b2529a08634b4..91dbb99203fbce2d 100644 --- a/arch/x86/boot/compressed/pgtable.h +++ b/arch/x86/boot/compressed/pgtable.h @@ -6,7 +6,7 @@ #define TRAMPOLINE_32BIT_PGTABLE_OFFSET 0 #define TRAMPOLINE_32BIT_CODE_OFFSET PAGE_SIZE -#define TRAMPOLINE_32BIT_CODE_SIZE 0x80 +#define TRAMPOLINE_32BIT_CODE_SIZE 0xA0 #define TRAMPOLINE_32BIT_STACK_END TRAMPOLINE_32BIT_SIZE