From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751704AbeBZSFI (ORCPT ); Mon, 26 Feb 2018 13:05:08 -0500 Received: from mga18.intel.com ([134.134.136.126]:2401 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175AbeBZSFD (ORCPT ); Mon, 26 Feb 2018 13:05:03 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,397,1515484800"; d="scan'208";a="20343785" From: "Kirill A. Shutemov" To: Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Borislav Petkov Cc: Linus Torvalds , Andy Lutomirski , Cyrill Gorcunov , Andi Kleen , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH 3/5] x86/boot/compressed/64: Save and restore trampoline memory Date: Mon, 26 Feb 2018 21:04:49 +0300 Message-Id: <20180226180451.86788-4-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180226180451.86788-1-kirill.shutemov@linux.intel.com> References: <20180226180451.86788-1-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The memory area we found for trampoline shouldn't contain anything useful. But let's preserve the data anyway. Just to be on safe side. paging_prepare() would save the data into a buffer. cleanup_trampoline() would restore it back once we are done with the trampoline. Signed-off-by: Kirill A. Shutemov --- arch/x86/boot/compressed/head_64.S | 10 ++++++++++ arch/x86/boot/compressed/pgtable_64.c | 13 +++++++++++++ 2 files changed, 23 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index d598d65db32c..8ba0582c65d5 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -355,6 +355,16 @@ ENTRY(startup_64) lretq lvl5: + /* + * cleanup_trampoline() would restore trampoline memory. + * + * RSI holds real mode data and needs to be preserved across + * this function call. + */ + pushq %rsi + call cleanup_trampoline + popq %rsi + /* Zero EFLAGS */ pushq $0 popfq diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index 21d5cc1cd5fa..01d08d3e3e43 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -1,5 +1,6 @@ #include #include "pgtable.h" +#include "../string.h" /* * __force_order is used by special_insns.h asm code to force instruction @@ -18,6 +19,9 @@ struct paging_config { unsigned long l5_required; }; +/* Buffer to preserve trampoline memory */ +static char trampoline_save[TRAMPOLINE_32BIT_SIZE]; + /* * Trampoline address will be printed by extract_kernel() for debugging * purposes. @@ -69,5 +73,14 @@ struct paging_config paging_prepare(void) trampoline_32bit = (unsigned long *)paging_config.trampoline_start; + /* Preserve trampoline memory */ + memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE); + return paging_config; } + +void cleanup_trampoline(void) +{ + /* Restore trampoline memory */ + memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE); +} -- 2.16.1