From nobody Sun Feb 8 02:34:47 2026 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 8CA81C77B75 for ; Mon, 22 May 2023 07:15:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232428AbjEVHPs (ORCPT ); Mon, 22 May 2023 03:15:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229987AbjEVHPF (ORCPT ); Mon, 22 May 2023 03:15:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 204D791; Mon, 22 May 2023 00:15:04 -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 AE44761DD3; Mon, 22 May 2023 07:15:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 670A6C4339B; Mon, 22 May 2023 07:14:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684739703; bh=4Bh3UcI6mBb60v5tgLvoAeGffUld7BrhFCXiRmmP3sE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B8PFMI8j/D51LvwF865+aX+iv+KDHkvt8iC4EiQ0I5a5plkeEOGknXXGhlLSVCdBk VejQ45+yCQrtU4u/hGOoy1OuEhq0NmMSI0i8QdnnFfkAz8UNd9WpBLADjT12WaVSvd RRlX1XYUOOVEafN9pN1wTvSXiJOJp/7tfJUmHb9pIiGrOGSufq1ANncvuh8eubQiQP 08jLV5QPB+HNvBkF3CEIBrmDfEqhFjKun10kvVrQ94fWodKSsFzt0sdh8Ksp2p6uzl uOLwsHkHT44yvjrvzsjDZQ4J5TiXTfhbORKXoRieGKBGmJtBrf4tRGlejT/W1VCGap u1DFoz+N1jZiA== 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 v3 07/21] x86/decompressor: Call trampoline as a normal function Date: Mon, 22 May 2023 09:14:01 +0200 Message-Id: <20230522071415.501717-8-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230522071415.501717-1-ardb@kernel.org> References: <20230522071415.501717-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2554; i=ardb@kernel.org; h=from:subject; bh=4Bh3UcI6mBb60v5tgLvoAeGffUld7BrhFCXiRmmP3sE=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JISVbzPTyXcGvbvdk7s59zjTFLSjIQEnfS8e2IGX29+utW 1ncSkI6SlkYxDgYZMUUWQRm/3238/REqVrnWbIwc1iZQIYwcHEKwEQWPmX4X/zz6beN5SwCHx4L CT6Of3pzfUzP73c+guvUTitru/p8LWD4H64gNdtP63XgnDXiXh8fGXM4Lv4sUl68o3Hh5Tg7x91 xLAA= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Move the long return to switch to 32-bit mode into the trampoline code so it can be called as an ordinary function. This will allow it to be called directly from C code in a subsequent patch. Acked-by: Kirill A. Shutemov Signed-off-by: Ard Biesheuvel --- 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 2d1b0ee94929f7ec..af45ddd8297a4a07 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -446,18 +446,9 @@ SYM_CODE_START(startup_64) /* Save the trampoline address in RCX */ movq %rax, %rcx =20 - /* - * 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 =3D 0 CS.D =3D 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 =20 @@ -540,16 +531,22 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) jmp *%rax SYM_FUNC_END(.Lrelocated) =20 - .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 =3D 0 CS.D =3D 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 =20 #define TRAMPOLINE_32BIT_CODE_OFFSET PAGE_SIZE -#define TRAMPOLINE_32BIT_CODE_SIZE 0x80 +#define TRAMPOLINE_32BIT_CODE_SIZE 0xA0 =20 #define TRAMPOLINE_32BIT_STACK_END TRAMPOLINE_32BIT_SIZE =20 --=20 2.39.2