From patchwork Mon Aug 7 16:27:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 711718 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 3A740C04FDF for ; Mon, 7 Aug 2023 16:28:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229790AbjHGQ2U (ORCPT ); Mon, 7 Aug 2023 12:28:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231564AbjHGQ1y (ORCPT ); Mon, 7 Aug 2023 12:27:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5259A1711; Mon, 7 Aug 2023 09:27:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DB3EF61F1F; Mon, 7 Aug 2023 16:27:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1CE0C433CA; Mon, 7 Aug 2023 16:27:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691425670; bh=/S4KCSV2J8sNlaIOIQwe9xIMj2pJ5zcMXcXITNkBoIY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bMAMTzPZtrtXo9yX1e4/XadlX0586thsURHf3kbrcKOf61+49rNjM3cpJAXeI8wUB SCm28VoZAYd8bpHnBbA4JTI9xWy2rOYyUERxsGXgzCZOYLz4v9EoUuUycOwCdrTDRS qxBPd6jzv/jmlqileK3j1YYSpu6EXDoHmvM8LU9HWUrQ+j/Y0pX0laxHN9eyjMvDtB fL/4649SsrtMoslX68g2fPiooxmSJWopu4Z16or74OUsaVg3Gu4noXa7m7wzVOnbfR Vpq6KewKbWZKN4lq+YBUES0yo+U2mRnaPP7K8+WNzOiIDBZXgZLY0WS6wozCH72ONb TX0ittmOV+hSA== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Borislav Petkov , Dave Hansen , Ingo Molnar , Thomas Gleixner Subject: [PATCH v9 04/23] x86/efistub: Simplify and clean up handover entry code Date: Mon, 7 Aug 2023 18:27:01 +0200 Message-Id: <20230807162720.545787-5-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230807162720.545787-1-ardb@kernel.org> References: <20230807162720.545787-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7453; i=ardb@kernel.org; h=from:subject; bh=/S4KCSV2J8sNlaIOIQwe9xIMj2pJ5zcMXcXITNkBoIY=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIeWitL9SsOD5/XxNP96HHC7i/S57droJ4/74dzy6a9UyJ qn2L2LpKGVhEONgkBVTZBGY/ffdztMTpWqdZ8nCzGFlAhnCwMUpABPZx8LI8EThSmVswE5Lzo1e azTu3/seNYG9KFjyRYHdZp7aerbnmgy/2R9+ndx4pSmv+DTrDJmvZ9Iytl836bHcua/qz3rWEI0 zjAA= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Now that the EFI entry code in assembler is only used by the optional and deprecated EFI handover protocol, and given that the EFI stub C code no longer returns to it, most of it can simply be dropped. While at it, clarify the symbol naming, by merging efi_main() and efi_stub_entry(), making the latter the shared entry point for all different boot modes that enter via the EFI stub. The efi32_stub_entry() and efi64_stub_entry() names are referenced explicitly by the tooling that populates the setup header, so these must be retained, but can be emitted as aliases of efi_stub_entry() where appropriate. Signed-off-by: Ard Biesheuvel --- Documentation/arch/x86/boot.rst | 2 +- arch/x86/boot/compressed/efi_mixed.S | 22 +++++++++++--------- arch/x86/boot/compressed/head_32.S | 11 ---------- arch/x86/boot/compressed/head_64.S | 12 ++--------- drivers/firmware/efi/libstub/x86-stub.c | 20 ++++++++++++++---- 5 files changed, 31 insertions(+), 36 deletions(-) diff --git a/Documentation/arch/x86/boot.rst b/Documentation/arch/x86/boot.rst index 33520ecdb37abfda..cdbca15a4fc23833 100644 --- a/Documentation/arch/x86/boot.rst +++ b/Documentation/arch/x86/boot.rst @@ -1417,7 +1417,7 @@ execution context provided by the EFI firmware. The function prototype for the handover entry point looks like this:: - efi_main(void *handle, efi_system_table_t *table, struct boot_params *bp) + efi_stub_entry(void *handle, efi_system_table_t *table, struct boot_params *bp) 'handle' is the EFI image handle passed to the boot loader by the EFI firmware, 'table' is the EFI system table - these are the first two diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S index 4ca70bf93dc0bdcd..dcc562c8f7f35162 100644 --- a/arch/x86/boot/compressed/efi_mixed.S +++ b/arch/x86/boot/compressed/efi_mixed.S @@ -26,8 +26,8 @@ * When booting in 64-bit mode on 32-bit EFI firmware, startup_64_mixed_mode() * is the first thing that runs after switching to long mode. Depending on * whether the EFI handover protocol or the compat entry point was used to - * enter the kernel, it will either branch to the 64-bit EFI handover - * entrypoint at offset 0x390 in the image, or to the 64-bit EFI PE/COFF + * enter the kernel, it will either branch to the common 64-bit EFI stub + * entrypoint efi_stub_entry() directly, or via the 64-bit EFI PE/COFF * entrypoint efi_pe_entry(). In the former case, the bootloader must provide a * struct bootparams pointer as the third argument, so the presence of such a * pointer is used to disambiguate. @@ -37,21 +37,23 @@ * | efi32_pe_entry |---->| | | +-----------+--+ * +------------------+ | | +------+----------------+ | * | startup_32 |---->| startup_64_mixed_mode | | - * +------------------+ | | +------+----------------+ V - * | efi32_stub_entry |---->| | | +------------------+ - * +------------------+ +------------+ +---->| efi64_stub_entry | - * +-------------+----+ - * +------------+ +----------+ | - * | startup_64 |<----| efi_main |<--------------+ - * +------------+ +----------+ + * +------------------+ | | +------+----------------+ | + * | efi32_stub_entry |---->| | | | + * +------------------+ +------------+ | | + * V | + * +------------+ +----------------+ | + * | startup_64 |<----| efi_stub_entry |<--------+ + * +------------+ +----------------+ */ SYM_FUNC_START(startup_64_mixed_mode) lea efi32_boot_args(%rip), %rdx mov 0(%rdx), %edi mov 4(%rdx), %esi +#ifdef CONFIG_EFI_HANDOVER_PROTOCOL mov 8(%rdx), %edx // saved bootparams pointer test %edx, %edx - jnz efi64_stub_entry + jnz efi_stub_entry +#endif /* * efi_pe_entry uses MS calling convention, which requires 32 bytes of * shadow space on the stack even if all arguments are passed in diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 987ae727cf9f0d04..8876ffe30e9a4819 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -150,17 +150,6 @@ SYM_FUNC_START(startup_32) jmp *%eax SYM_FUNC_END(startup_32) -#ifdef CONFIG_EFI_STUB -SYM_FUNC_START(efi32_stub_entry) - add $0x4, %esp - movl 8(%esp), %esi /* save boot_params pointer */ - call efi_main - /* efi_main returns the possibly relocated address of startup_32 */ - jmp *%eax -SYM_FUNC_END(efi32_stub_entry) -SYM_FUNC_ALIAS(efi_stub_entry, efi32_stub_entry) -#endif - .text SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index f732426d3b483139..e6880208b9a1b90a 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -542,19 +542,11 @@ trampoline_return: jmp *%rax SYM_CODE_END(startup_64) -#ifdef CONFIG_EFI_STUB -#ifdef CONFIG_EFI_HANDOVER_PROTOCOL +#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL) .org 0x390 -#endif SYM_FUNC_START(efi64_stub_entry) - and $~0xf, %rsp /* realign the stack */ - movq %rdx, %rbx /* save boot_params pointer */ - call efi_main - movq %rbx,%rsi - leaq rva(startup_64)(%rax), %rax - jmp *%rax + jmp efi_stub_entry SYM_FUNC_END(efi64_stub_entry) -SYM_FUNC_ALIAS(efi_stub_entry, efi64_stub_entry) #endif .text diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 40a10db2d85e7942..3f3b3edf7a387d7c 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -817,9 +817,9 @@ static void __noreturn enter_kernel(unsigned long kernel_addr, * 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, - struct boot_params *boot_params) +void __noreturn efi_stub_entry(efi_handle_t handle, + efi_system_table_t *sys_table_arg, + struct boot_params *boot_params) { unsigned long bzimage_addr = (unsigned long)startup_32; unsigned long buffer_start, buffer_end; @@ -964,7 +964,19 @@ asmlinkage unsigned long efi_main(efi_handle_t handle, enter_kernel(bzimage_addr, boot_params); fail: - efi_err("efi_main() failed!\n"); + efi_err("efi_stub_entry() failed!\n"); efi_exit(handle, status); } + +#ifdef CONFIG_EFI_HANDOVER_PROTOCOL +#ifndef CONFIG_EFI_MIXED +extern __alias(efi_stub_entry) +void efi32_stub_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg, + struct boot_params *boot_params); + +extern __alias(efi_stub_entry) +void efi64_stub_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg, + struct boot_params *boot_params); +#endif +#endif