From patchwork Wed Jun 7 07:23:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 693129 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 CA06EC7EE43 for ; Wed, 7 Jun 2023 07:26:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238911AbjFGH0Y (ORCPT ); Wed, 7 Jun 2023 03:26:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239160AbjFGHZx (ORCPT ); Wed, 7 Jun 2023 03:25:53 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4B891FED; Wed, 7 Jun 2023 00:24:45 -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 2A0ED63542; Wed, 7 Jun 2023 07:24:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE859C433A0; Wed, 7 Jun 2023 07:23:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686122640; bh=0wgPR8cosROASbxhizaWEh3zQ4j+H/DEB9t5hilAPDo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pWwvL1E8pkq/VHu7SKqTWzB5IsBgx4UbU58H2oaGOtkSndAPzouOdgkZ46eMTGO8L gekBQ9RF8fjOVy+m7hXAmWVgYCLKNQyFbVaddTwSCU5Iaw78exac+o0Fxrngck8VEc ikpqE/Jx6aG9KdVljqYBO3V6TQm5FPF23NdVe/IpMZup1d7Ce1xg267r9l4UuhH1ve JOk8S+A0T/E87x2VpzCaDSSvkKaJ0UE9KIbtkoN29JU27f2wOxKpkaa+FK/0zdfSwT OFsElmTqK0gQOdinmyHj8imQUwnxS4YL8LGxYnmZX2cbT+5mZFO2boaudaPomPzhfY gaDmlKOTzxHwg== 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 , Joerg Roedel Subject: [PATCH v5 01/20] x86/efistub: Branch straight to kernel entry point from C code Date: Wed, 7 Jun 2023 09:23:23 +0200 Message-Id: <20230607072342.4054036-2-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230607072342.4054036-1-ardb@kernel.org> References: <20230607072342.4054036-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1927; i=ardb@kernel.org; h=from:subject; bh=0wgPR8cosROASbxhizaWEh3zQ4j+H/DEB9t5hilAPDo=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIaXBILVkwumLTU3H5j/cIH/66+vkV6UeBj/PLN5wZM6TP 89vcTMLdpSyMIhxMMiKKbIIzP77bufpiVK1zrNkYeawMoEMYeDiFICJ3GRi+B+p8rz94KHqOPOD idd2cLMx/C6+sVndsE9l34VujQ92byMZ/inqvZv5UkxSInIp75QN//crGk/65nbjcTpnhXpMZYS cITcA X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Instead of returning to the calling code in assembler that does nothing more than perform an indirect call with the boot_params pointer in register ESI/RSI, perform the jump directly from the EFI stub C code. This will allow the asm entrypoint code to be dropped entirely in subsequent patches. Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/x86-stub.c | 21 ++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 220be75a5cdc1f4c..d4a730f053bdcbfa 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -803,10 +803,19 @@ static efi_status_t exit_boot(struct boot_params *boot_params, void *handle) return EFI_SUCCESS; } +static void __noreturn enter_kernel(unsigned long kernel_addr, + struct boot_params *boot_params) +{ + /* enter decompressed kernel with boot_params pointer in RSI/ESI */ + asm("jmp *%0"::"r"(kernel_addr), "S"(boot_params)); + + unreachable(); +} + /* - * On success, we return the address of startup_32, which has potentially been - * relocated by efi_relocate_kernel. - * On failure, we exit to the firmware via efi_exit instead of returning. + * On success, this routine will jump to the relocated image directly and never + * return. On failure, it will exit to the firmware via efi_exit() instead of + * returning. */ asmlinkage unsigned long efi_main(efi_handle_t handle, efi_system_table_t *sys_table_arg, @@ -950,7 +959,11 @@ asmlinkage unsigned long efi_main(efi_handle_t handle, goto fail; } - return bzimage_addr; + if (IS_ENABLED(CONFIG_X86_64)) + /* add offset of startup_64() */ + bzimage_addr += 0x200; + + enter_kernel(bzimage_addr, boot_params); fail: efi_err("efi_main() failed!\n");