From patchwork Tue Nov 22 11:12:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13052207 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 691E8C07E9D for ; Tue, 22 Nov 2022 11:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232930AbiKVLNF (ORCPT ); Tue, 22 Nov 2022 06:13:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233033AbiKVLMu (ORCPT ); Tue, 22 Nov 2022 06:12:50 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F8002673; Tue, 22 Nov 2022 03:12:48 -0800 (PST) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id 5F9CF40737BF; Tue, 22 Nov 2022 11:12:41 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 5F9CF40737BF DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1669115561; bh=yLQbGes8MGXboxk0W0ZEpZH6+wuhbRcghPYnIxLpUGE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nXF1x2Zs9hgLsP6hyg+4GamD9SM67ZWEuTf5NPpXk1gRC1LYnMzHVmlsTYWjMZQka j2KMoOit5Cl6d5Gh4iITL6MLul5NRLNQmCEQDNmQz8ySaheTi2NzeaozLsPBNU7di1 8dkuNtO6oJGySRYudBBLyTcachKtdGNhrjqAUumI= From: Evgeniy Baskov To: Ard Biesheuvel Cc: Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , "Limonciello, Mario" , joeyli , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3 05/24] x86/boot: Support 4KB pages for identity mapping Date: Tue, 22 Nov 2022 14:12:14 +0300 Message-Id: <4fe2e1ba651511d279f6c32af1f0c993083e64ac.1668958803.git.baskov@ispras.ru> X-Mailer: git-send-email 2.37.4 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Current identity mapping code only supports 2M and 1G pages. 4KB pages are desirable for better memory protection granularity in compressed kernel code. Change identity mapping code to support 4KB pages and memory remapping with different attributes. Tested-by: Mario Limonciello Signed-off-by: Evgeniy Baskov --- arch/x86/include/asm/init.h | 1 + arch/x86/mm/ident_map.c | 185 +++++++++++++++++++++++++++++------- 2 files changed, 154 insertions(+), 32 deletions(-) diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h index 5f1d3c421f68..a8277ee82c51 100644 --- a/arch/x86/include/asm/init.h +++ b/arch/x86/include/asm/init.h @@ -8,6 +8,7 @@ struct x86_mapping_info { unsigned long page_flag; /* page flag for PMD or PUD entry */ unsigned long offset; /* ident mapping offset */ bool direct_gbpages; /* PUD level 1GB page support */ + bool allow_4kpages; /* Allow more granular mappings with 4K pages */ unsigned long kernpg_flag; /* kernel pagetable flag override */ }; diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c index 968d7005f4a7..662e794a325d 100644 --- a/arch/x86/mm/ident_map.c +++ b/arch/x86/mm/ident_map.c @@ -4,24 +4,127 @@ * included by both the compressed kernel and the regular kernel. */ -static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page, - unsigned long addr, unsigned long end) +static void ident_pte_init(struct x86_mapping_info *info, pte_t *pte_page, + unsigned long addr, unsigned long end, + unsigned long flags) { - addr &= PMD_MASK; - for (; addr < end; addr += PMD_SIZE) { + addr &= PAGE_MASK; + for (; addr < end; addr += PAGE_SIZE) { + pte_t *pte = pte_page + pte_index(addr); + + set_pte(pte, __pte((addr - info->offset) | flags)); + } +} + +pte_t *ident_split_large_pmd(struct x86_mapping_info *info, + pmd_t *pmdp, unsigned long page_addr) +{ + unsigned long pmd_addr, page_flags; + pte_t *pte; + + pte = (pte_t *)info->alloc_pgt_page(info->context); + if (!pte) + return NULL; + + pmd_addr = page_addr & PMD_MASK; + + /* Not a large page - clear PSE flag */ + page_flags = pmd_flags(*pmdp) & ~_PSE; + ident_pte_init(info, pte, pmd_addr, pmd_addr + PMD_SIZE, page_flags); + + return pte; +} + +static int ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page, + unsigned long addr, unsigned long end, + unsigned long flags) +{ + unsigned long next; + bool new_table = 0; + + for (; addr < end; addr = next) { pmd_t *pmd = pmd_page + pmd_index(addr); + pte_t *pte; - if (pmd_present(*pmd)) + next = (addr & PMD_MASK) + PMD_SIZE; + if (next > end) + next = end; + + /* + * Use 2M pages if 4k pages are not allowed or + * we are not mapping extra, i.e. address and size are aligned. + */ + + if (!info->allow_4kpages || + (!(addr & ~PMD_MASK) && next == addr + PMD_SIZE)) { + + pmd_t pmdval; + + addr &= PMD_MASK; + pmdval = __pmd((addr - info->offset) | flags | _PSE); + set_pmd(pmd, pmdval); continue; + } + + /* + * If currently mapped page is large, we need to split it. + * The case when we don't can remap 2M page to 2M page + * with different flags is already covered above. + * + * If there's nothing mapped to desired address, + * we need to allocate new page table. + */ - set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag)); + if (pmd_large(*pmd)) { + pte = ident_split_large_pmd(info, pmd, addr); + new_table = 1; + } else if (!pmd_present(*pmd)) { + pte = (pte_t *)info->alloc_pgt_page(info->context); + new_table = 1; + } else { + pte = pte_offset_kernel(pmd, 0); + new_table = 0; + } + + if (!pte) + return -ENOMEM; + + ident_pte_init(info, pte, addr, next, flags); + + if (new_table) + set_pmd(pmd, __pmd(__pa(pte) | info->kernpg_flag)); } + + return 0; } + +pmd_t *ident_split_large_pud(struct x86_mapping_info *info, + pud_t *pudp, unsigned long page_addr) +{ + unsigned long pud_addr, page_flags; + pmd_t *pmd; + + pmd = (pmd_t *)info->alloc_pgt_page(info->context); + if (!pmd) + return NULL; + + pud_addr = page_addr & PUD_MASK; + + /* Not a large page - clear PSE flag */ + page_flags = pud_flags(*pudp) & ~_PSE; + ident_pmd_init(info, pmd, pud_addr, pud_addr + PUD_SIZE, page_flags); + + return pmd; +} + + static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, unsigned long addr, unsigned long end) { unsigned long next; + bool new_table = 0; + int result; for (; addr < end; addr = next) { pud_t *pud = pud_page + pud_index(addr); @@ -31,28 +134,39 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, if (next > end) next = end; + /* Use 1G pages only if forced, even if they are supported. */ if (info->direct_gbpages) { pud_t pudval; - - if (pud_present(*pud)) - continue; + unsigned long flags; addr &= PUD_MASK; - pudval = __pud((addr - info->offset) | info->page_flag); + flags = info->page_flag | _PSE; + pudval = __pud((addr - info->offset) | flags); + set_pud(pud, pudval); continue; } - if (pud_present(*pud)) { + if (pud_large(*pud)) { + pmd = ident_split_large_pud(info, pud, addr); + new_table = 1; + } else if (!pud_present(*pud)) { + pmd = (pmd_t *)info->alloc_pgt_page(info->context); + new_table = 1; + } else { pmd = pmd_offset(pud, 0); - ident_pmd_init(info, pmd, addr, next); - continue; + new_table = 0; } - pmd = (pmd_t *)info->alloc_pgt_page(info->context); + if (!pmd) return -ENOMEM; - ident_pmd_init(info, pmd, addr, next); - set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); + + result = ident_pmd_init(info, pmd, addr, next, info->page_flag); + if (result) + return result; + + if (new_table) + set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag)); } return 0; @@ -63,6 +177,7 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, { unsigned long next; int result; + bool new_table = 0; for (; addr < end; addr = next) { p4d_t *p4d = p4d_page + p4d_index(addr); @@ -72,15 +187,14 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, if (next > end) next = end; - if (p4d_present(*p4d)) { + if (!p4d_present(*p4d)) { + pud = (pud_t *)info->alloc_pgt_page(info->context); + new_table = 1; + } else { pud = pud_offset(p4d, 0); - result = ident_pud_init(info, pud, addr, next); - if (result) - return result; - - continue; + new_table = 0; } - pud = (pud_t *)info->alloc_pgt_page(info->context); + if (!pud) return -ENOMEM; @@ -88,19 +202,22 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, if (result) return result; - set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); + if (new_table) + set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag)); } return 0; } -int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, - unsigned long pstart, unsigned long pend) +int kernel_ident_mapping_init(struct x86_mapping_info *info, + pgd_t *pgd_page, unsigned long pstart, + unsigned long pend) { unsigned long addr = pstart + info->offset; unsigned long end = pend + info->offset; unsigned long next; int result; + bool new_table; /* Set the default pagetable flags if not supplied */ if (!info->kernpg_flag) @@ -117,20 +234,24 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, if (next > end) next = end; - if (pgd_present(*pgd)) { + if (!pgd_present(*pgd)) { + p4d = (p4d_t *)info->alloc_pgt_page(info->context); + new_table = 1; + } else { p4d = p4d_offset(pgd, 0); - result = ident_p4d_init(info, p4d, addr, next); - if (result) - return result; - continue; + new_table = 0; } - p4d = (p4d_t *)info->alloc_pgt_page(info->context); if (!p4d) return -ENOMEM; + result = ident_p4d_init(info, p4d, addr, next); if (result) return result; + + if (!new_table) + continue; + if (pgtable_l5_enabled()) { set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag)); } else {