From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB9F5C33CA9 for ; Mon, 13 Jan 2020 17:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78F3A222C2 for ; Mon, 13 Jan 2020 17:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578936193; bh=V8FfWZwqcvkcPv0qLBBwy6zI1GWJXarK+QE6YYnWud0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YgvsHK7/q1MEIeGmvMLKZWcEE0rOTKCpXmr5yl8I2EvRNlugoBTG1bwsXMfo5v/yn 9RqEPOacx+F2QWFjwSyXrT0kPnxqkbzbk8zWeuH6z1cNGlivydHVWlZa9jxKFMQIGf jon2saQ77k84CjnukkbmXO6p8Tlf6vgbIevZTBDc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728827AbgAMRXM (ORCPT ); Mon, 13 Jan 2020 12:23:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:41334 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728811AbgAMRXM (ORCPT ); Mon, 13 Jan 2020 12:23:12 -0500 Received: from dogfood.home (amontpellier-657-1-18-247.w109-210.abo.wanadoo.fr [109.210.65.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 188C1214AF; Mon, 13 Jan 2020 17:23:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578936191; bh=V8FfWZwqcvkcPv0qLBBwy6zI1GWJXarK+QE6YYnWud0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pv/F55+gtJTUxHqaYX/wT7LaQpEtSKcrnjZ4NTvhMYH4ofzMC0tRAZkQL0EhZrVlg tqypwMAp0v2cN83VqM4MnOH7wLkiVxzVPFnyJSms+F+duplmukubp5W1/HQbJUzjUz xMh3AV5zC/7BaIhbwzZeGbN+rJumQdIc/VbMRwGk= From: Ard Biesheuvel To: linux-efi@vger.kernel.org, Ingo Molnar , Thomas Gleixner Cc: Ard Biesheuvel , linux-kernel@vger.kernel.org, Anshuman Khandual , Arnd Bergmann , Dan Williams , Dave Young , Saravana Kannan Subject: [PATCH 02/13] efi/libstub/x86: use mandatory 16-byte stack alignment in mixed mode Date: Mon, 13 Jan 2020 18:22:34 +0100 Message-Id: <20200113172245.27925-3-ardb@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200113172245.27925-1-ardb@kernel.org> References: <20200113172245.27925-1-ardb@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Reduce the stack frame of the EFI stub's mixed mode thunk routine by 8 bytes, by moving the GDT and return addresses to EBP and EBX, which we need to preserve anyway, since their top halves will be cleared by the call into 32-bit firmware code. Doing so results in the UEFI code being entered with a 16 byte aligned stack, as mandated by the UEFI spec, fixing the last occurrence in the 64-bit kernel where we violate this requirement. Also, move the saved GDT from a global variable to an unused part of the stack frame, and touch up some other parts of the code. Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/efi_thunk_64.S | 46 +++++++------------------ 1 file changed, 13 insertions(+), 33 deletions(-) diff --git a/arch/x86/boot/compressed/efi_thunk_64.S b/arch/x86/boot/compressed/efi_thunk_64.S index d040ff5458e5..8fb7f6799c52 100644 --- a/arch/x86/boot/compressed/efi_thunk_64.S +++ b/arch/x86/boot/compressed/efi_thunk_64.S @@ -27,12 +27,9 @@ SYM_FUNC_START(__efi64_thunk) push %rbp push %rbx - subq $8, %rsp - leaq 1f(%rip), %rax - movl %eax, 4(%rsp) - leaq efi_gdt64(%rip), %rax - movl %eax, (%rsp) - movl %eax, 2(%rax) /* Fixup the gdt base address */ + leaq 1f(%rip), %rbp + leaq efi_gdt64(%rip), %rbx + movl %ebx, 2(%rbx) /* Fixup the gdt base address */ movl %ds, %eax push %rax @@ -48,12 +45,10 @@ SYM_FUNC_START(__efi64_thunk) movl %esi, 0x0(%rsp) movl %edx, 0x4(%rsp) movl %ecx, 0x8(%rsp) - movq %r8, %rsi - movl %esi, 0xc(%rsp) - movq %r9, %rsi - movl %esi, 0x10(%rsp) + movl %r8d, 0xc(%rsp) + movl %r9d, 0x10(%rsp) - sgdt save_gdt(%rip) + sgdt 0x14(%rsp) /* * Switch to gdt with 32-bit segments. This is the firmware GDT @@ -68,11 +63,10 @@ SYM_FUNC_START(__efi64_thunk) pushq %rax lretq -1: addq $32, %rsp +1: lgdt 0x14(%rsp) + addq $32, %rsp movq %rdi, %rax - lgdt save_gdt(%rip) - pop %rbx movl %ebx, %ss pop %rbx @@ -83,15 +77,9 @@ SYM_FUNC_START(__efi64_thunk) /* * Convert 32-bit status code into 64-bit. */ - test %rax, %rax - jz 1f - movl %eax, %ecx - andl $0x0fffffff, %ecx - andl $0xf0000000, %eax - shl $32, %rax - or %rcx, %rax -1: - addq $8, %rsp + roll $1, %eax + rorq $1, %rax + pop %rbx pop %rbp ret @@ -135,9 +123,7 @@ SYM_FUNC_START_LOCAL(efi_enter32) */ cli - movl 56(%esp), %eax - movl %eax, 2(%eax) - lgdtl (%eax) + lgdtl (%ebx) movl %cr4, %eax btsl $(X86_CR4_PAE_BIT), %eax @@ -154,9 +140,8 @@ SYM_FUNC_START_LOCAL(efi_enter32) xorl %eax, %eax lldt %ax - movl 60(%esp), %eax pushl $__KERNEL_CS - pushl %eax + pushl %ebp /* Enable paging */ movl %cr0, %eax @@ -172,11 +157,6 @@ SYM_DATA_START(efi32_boot_gdt) .quad 0 SYM_DATA_END(efi32_boot_gdt) -SYM_DATA_START_LOCAL(save_gdt) - .word 0 - .quad 0 -SYM_DATA_END(save_gdt) - SYM_DATA_START(efi_gdt64) .word efi_gdt64_end - efi_gdt64 .long 0 /* Filled out by user */ -- 2.20.1