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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 BD1A3C433E0 for ; Sat, 6 Feb 2021 12:57:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93C2E64E51 for ; Sat, 6 Feb 2021 12:57:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230086AbhBFM5f (ORCPT ); Sat, 6 Feb 2021 07:57:35 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:53962 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230048AbhBFM5M (ORCPT ); Sat, 6 Feb 2021 07:57:12 -0500 Date: Sat, 06 Feb 2021 12:56:21 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1612616182; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D2di6FPuLkHz2k4bwi3Z9U6bVN1xW/5AYBB4VCGepUI=; b=ZP0O57l8rOaA/nxSbO3pbTJcomx40aR4XNqGBzeEuqxEuXVe6/fFRmvOux1xaONJuc1Ogs 4Tc/2g7/AvrEuAIjTdXP5AxZLVVqA6QqVGnf3IokvuAwQ2HroWYhr081NZxnvVbf+5dZ07 y82rfKUy5N7JOxl0IbJdmlDEBMM+StUBVAzbbUusSpnKtFzmb2BiMNUs2sSVMLNNLkWJe9 FEbw2Zh2UArcGLSumEmBf+OldBOYwLHj1Bjp+n0ES78/69A38cotJD761DQhRmL3+InSD/ ntSnwm7imPYL9LwmhcF16Y/W0g46jOMEjJpjy2ZFcDkwWfKnxVILd88c8J3p6w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1612616182; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D2di6FPuLkHz2k4bwi3Z9U6bVN1xW/5AYBB4VCGepUI=; b=PzEQG1m1m+ZycG3wSQ/IHizjeVXdQfMfTsf8CtqASp9QHomoa8O0O5iIprOVmRap9UgOOu QLtSa2K1lxy98yDA== From: "tip-bot2 for Borislav Petkov" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/efi: Remove EFI PGD build time checks Cc: Arnd Bergmann , Borislav Petkov , Nathan Chancellor , Ard Biesheuvel , Nick Desaulniers , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210107223424.4135538-1-arnd@kernel.org> References: <20210107223424.4135538-1-arnd@kernel.org> MIME-Version: 1.0 Message-ID: <161261618116.23325.7532441736961791743.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 816ef8d7a2c4182e19bc06ab65751cb9e3951e94 Gitweb: https://git.kernel.org/tip/816ef8d7a2c4182e19bc06ab65751cb9e3951e94 Author: Borislav Petkov AuthorDate: Fri, 05 Feb 2021 11:31:31 +01:00 Committer: Borislav Petkov CommitterDate: Sat, 06 Feb 2021 13:54:14 +01:00 x86/efi: Remove EFI PGD build time checks With CONFIG_X86_5LEVEL, CONFIG_UBSAN and CONFIG_UBSAN_UNSIGNED_OVERFLOW enabled, clang fails the build with x86_64-linux-ld: arch/x86/platform/efi/efi_64.o: in function `efi_sync_low_kernel_mappings': efi_64.c:(.text+0x22c): undefined reference to `__compiletime_assert_354' which happens due to -fsanitize=unsigned-integer-overflow being enabled: -fsanitize=unsigned-integer-overflow: Unsigned integer overflow, where the result of an unsigned integer computation cannot be represented in its type. Unlike signed integer overflow, this is not undefined behavior, but it is often unintentional. This sanitizer does not check for lossy implicit conversions performed before such a computation (see -fsanitize=implicit-conversion). and that fires when the (intentional) EFI_VA_START/END defines overflow an unsigned long, leading to the assertion expressions not getting optimized away (on GCC they do)... However, those checks are superfluous: the runtime services mapping code already makes sure the ranges don't overshoot EFI_VA_END as the EFI mapping range is hardcoded. On each runtime services call, it is switched to the EFI-specific PGD and even if mappings manage to escape that last PGD, this won't remain unnoticed for long. So rip them out. See https://github.com/ClangBuiltLinux/linux/issues/256 for more info. Reported-by: Arnd Bergmann Signed-off-by: Borislav Petkov Reviewed-by: Nathan Chancellor Acked-by: Ard Biesheuvel Tested-by: Nick Desaulniers Tested-by: Nathan Chancellor Link: http://lkml.kernel.org/r/20210107223424.4135538-1-arnd@kernel.org --- arch/x86/platform/efi/efi_64.c | 19 ------------------- 1 file changed, 19 deletions(-) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index e1e8d4e..8efd003 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -115,31 +115,12 @@ void efi_sync_low_kernel_mappings(void) pud_t *pud_k, *pud_efi; pgd_t *efi_pgd = efi_mm.pgd; - /* - * We can share all PGD entries apart from the one entry that - * covers the EFI runtime mapping space. - * - * Make sure the EFI runtime region mappings are guaranteed to - * only span a single PGD entry and that the entry also maps - * other important kernel regions. - */ - MAYBE_BUILD_BUG_ON(pgd_index(EFI_VA_END) != pgd_index(MODULES_END)); - MAYBE_BUILD_BUG_ON((EFI_VA_START & PGDIR_MASK) != - (EFI_VA_END & PGDIR_MASK)); - pgd_efi = efi_pgd + pgd_index(PAGE_OFFSET); pgd_k = pgd_offset_k(PAGE_OFFSET); num_entries = pgd_index(EFI_VA_END) - pgd_index(PAGE_OFFSET); memcpy(pgd_efi, pgd_k, sizeof(pgd_t) * num_entries); - /* - * As with PGDs, we share all P4D entries apart from the one entry - * that covers the EFI runtime mapping space. - */ - BUILD_BUG_ON(p4d_index(EFI_VA_END) != p4d_index(MODULES_END)); - BUILD_BUG_ON((EFI_VA_START & P4D_MASK) != (EFI_VA_END & P4D_MASK)); - pgd_efi = efi_pgd + pgd_index(EFI_VA_END); pgd_k = pgd_offset_k(EFI_VA_END); p4d_efi = p4d_offset(pgd_efi, 0);