From patchwork Sun Jun 26 21:55:27 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Lutomirski X-Patchwork-Id: 9199639 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 79C4860752 for ; Sun, 26 Jun 2016 21:57:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6C32A28521 for ; Sun, 26 Jun 2016 21:57:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5DACC2855A; Sun, 26 Jun 2016 21:57:07 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 2F78328521 for ; Sun, 26 Jun 2016 21:57:06 +0000 (UTC) Received: (qmail 32235 invoked by uid 550); 26 Jun 2016 21:56:23 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 32076 invoked from network); 26 Jun 2016 21:56:21 -0000 From: Andy Lutomirski To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Borislav Petkov , Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Jann Horn , Heiko Carstens , Andy Lutomirski , Matt Fleming , linux-efi@vger.kernel.org Date: Sun, 26 Jun 2016 14:55:27 -0700 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: X-Virus-Scanned: ClamAV using ClamSMTP Subject: [kernel-hardening] [PATCH v4 05/29] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() X-Virus-Scanned: ClamAV using ClamSMTP kernel_unmap_pages_in_pgd() is dangerous: if a pgd entry in init_mm.pgd were to be cleared, callers would need to ensure that the pgd entry hadn't been propagated to any other pgd. Its only caller was efi_cleanup_page_tables(), and that, in turn, was unused, so just delete both functions. This leaves a couple of other helpers unused, so delete them, too. Cc: Matt Fleming Cc: linux-efi@vger.kernel.org Reviewed-by: Matt Fleming Signed-off-by: Andy Lutomirski Acked-by: Borislav Petkov --- arch/x86/include/asm/efi.h | 1 - arch/x86/include/asm/pgtable_types.h | 2 -- arch/x86/mm/pageattr.c | 28 ---------------------------- arch/x86/platform/efi/efi.c | 2 -- arch/x86/platform/efi/efi_32.c | 3 --- arch/x86/platform/efi/efi_64.c | 5 ----- 6 files changed, 41 deletions(-) diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 78d1e7467eae..45ea38df86d4 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -125,7 +125,6 @@ extern void __init efi_map_region_fixed(efi_memory_desc_t *md); extern void efi_sync_low_kernel_mappings(void); extern int __init efi_alloc_page_tables(void); extern int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages); -extern void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages); extern void __init old_map_region(efi_memory_desc_t *md); extern void __init runtime_code_page_mkexec(void); extern void __init efi_runtime_update_mappings(void); diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index 7b5efe264eff..0b9f58ad10c8 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -475,8 +475,6 @@ extern pmd_t *lookup_pmd_address(unsigned long address); extern phys_addr_t slow_virt_to_phys(void *__address); extern int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address, unsigned numpages, unsigned long page_flags); -void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address, - unsigned numpages); #endif /* !__ASSEMBLY__ */ #endif /* _ASM_X86_PGTABLE_DEFS_H */ diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 6a8026918bf6..762162af3662 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -746,18 +746,6 @@ static bool try_to_free_pmd_page(pmd_t *pmd) return true; } -static bool try_to_free_pud_page(pud_t *pud) -{ - int i; - - for (i = 0; i < PTRS_PER_PUD; i++) - if (!pud_none(pud[i])) - return false; - - free_page((unsigned long)pud); - return true; -} - static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end) { pte_t *pte = pte_offset_kernel(pmd, start); @@ -871,16 +859,6 @@ static void unmap_pud_range(pgd_t *pgd, unsigned long start, unsigned long end) */ } -static void unmap_pgd_range(pgd_t *root, unsigned long addr, unsigned long end) -{ - pgd_t *pgd_entry = root + pgd_index(addr); - - unmap_pud_range(pgd_entry, addr, end); - - if (try_to_free_pud_page((pud_t *)pgd_page_vaddr(*pgd_entry))) - pgd_clear(pgd_entry); -} - static int alloc_pte_page(pmd_t *pmd) { pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK); @@ -1993,12 +1971,6 @@ out: return retval; } -void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address, - unsigned numpages) -{ - unmap_pgd_range(root, address, address + (numpages << PAGE_SHIFT)); -} - /* * The testcases use internal knowledge of the implementation that shouldn't * be exposed to the rest of the kernel. Include these directly here. diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index f93545e7dc54..62986e5fbdba 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -978,8 +978,6 @@ static void __init __efi_enter_virtual_mode(void) * EFI mixed mode we need all of memory to be accessible when * we pass parameters to the EFI runtime services in the * thunking code. - * - * efi_cleanup_page_tables(__pa(new_memmap), 1 << pg_shift); */ free_pages((unsigned long)new_memmap, pg_shift); diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c index 338402b91d2e..cef39b097649 100644 --- a/arch/x86/platform/efi/efi_32.c +++ b/arch/x86/platform/efi/efi_32.c @@ -49,9 +49,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) { return 0; } -void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages) -{ -} void __init efi_map_region(efi_memory_desc_t *md) { diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index b226b3f497f1..d288dcea1ffe 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -285,11 +285,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) return 0; } -void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages) -{ - kernel_unmap_pages_in_pgd(efi_pgd, pa_memmap, num_pages); -} - static void __init __map_region(efi_memory_desc_t *md, u64 va) { unsigned long flags = _PAGE_RW;