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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6828C433F5 for ; Wed, 10 Nov 2021 10:57:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AE8B61260 for ; Wed, 10 Nov 2021 10:57:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231556AbhKJK7q (ORCPT ); Wed, 10 Nov 2021 05:59:46 -0500 Received: from mail.ispras.ru ([83.149.199.84]:53924 "EHLO mail.ispras.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231420AbhKJK7i (ORCPT ); Wed, 10 Nov 2021 05:59:38 -0500 Received: from localhost.localdomain (unknown [80.240.223.29]) by mail.ispras.ru (Postfix) with ESMTPSA id 7B58740A2BBF; Wed, 10 Nov 2021 10:47:01 +0000 (UTC) From: Baskov Evgeniy To: Ard Biesheuvel Cc: Baskov Evgeniy , Borislav Petkov , Dave Hansen , Ingo Molnar , Jonathan Corbet , Thomas Gleixner , x86@kernel.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC 2/5] efi/x86_64: set page table if provided by libstub Date: Wed, 10 Nov 2021 13:46:10 +0300 Message-Id: <20211110104613.23881-3-baskov@ispras.ru> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211110104613.23881-1-baskov@ispras.ru> References: <20211110104613.23881-1-baskov@ispras.ru> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is desired to be able to switch pages tables before jumping to potentially relocated code while booting via UEFI. The easiest way to achieve that is to do it in assembly immediately after returning from efi_main(). Add mechanism to switch page table to one provided by libstub. Signed-off-by: Baskov Evgeniy --- arch/x86/boot/compressed/head_64.S | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 572c535cf45b..1e467fdefd9d 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -540,6 +540,17 @@ SYM_FUNC_START_ALIAS(efi_stub_entry) movq %rdx, %rbx /* save boot_params pointer */ call efi_main movq %rbx,%rsi + + /* + * Switch page table to the one constructed by libstub if provided + * It is required to be done here because stack is not mapped + * in new page table. + */ + movq efi_temp_pgtable(%rip), %rbx + testq %rbx, %rbx + jz 1f + movq %rbx, %cr3 +1: leaq rva(startup_64)(%rax), %rax jmp *%rax SYM_FUNC_END(efi64_stub_entry) @@ -736,6 +747,7 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end) #ifdef CONFIG_EFI_STUB SYM_DATA(image_offset, .long 0) +SYM_DATA(efi_temp_pgtable, .quad 0) #endif #ifdef CONFIG_EFI_MIXED SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0) -- 2.33.1