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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AC8DECAAA1 for ; Thu, 15 Sep 2022 19:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229772AbiIOTl5 (ORCPT ); Thu, 15 Sep 2022 15:41:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230014AbiIOTlX (ORCPT ); Thu, 15 Sep 2022 15:41:23 -0400 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FFCA9D671 for ; Thu, 15 Sep 2022 12:38:13 -0700 (PDT) Received: by mail-qk1-x730.google.com with SMTP id h28so14177273qka.0 for ; Thu, 15 Sep 2022 12:38:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date; bh=IFHyF3bgLmRCz7L1OXA+Yzmng1wr1QB+FbuCdYFy/tI=; b=P7wrNtaVdIOrlW37f0LPcfnU8hmMUK2jaYeanePYkOaTMdlGNSguzpBt73lkoKp0Sb i7B7+qgdb1F6INrk3zgGj7KX82s4XVBJ4OnjZgn4smtDkK9krE1kaK/rtNzNpYUDOiwV ZlBtHLtF7ylHYIQ6CqRPnp/Ip0/nITf4wEWkJab/i3LeBNse9CbM/UBN2ERF2vwlOb8t f9Y6w1fxmvmcKYNc9AFLG2pZDF75Ih+DQC39s2hCVzzc4ARglhDXZax0+qjBT6zrbj3U NNXkkCiEnAN+mEky/USAsQdyn8r0WkICeuLhvccfnawu91AnN+S1C/0Npo4JD8luo2iu 1Hww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date; bh=IFHyF3bgLmRCz7L1OXA+Yzmng1wr1QB+FbuCdYFy/tI=; b=J4M98byOPR/fk6XUHnRQ2shrzAD9z/JK0QI6EfoSrJT5qNQX2Hc10hojzyBurS4v1s uZDV3bSOGEPRTJ/87W2tKin34VImiwVUB9g1gf2cjvsVyA4//qYgAvLcweOlK5zvEh5M xSEifQfegy/J3ynZZofJxoqSG3eWqDT60bdEj2hq3KMWYCcEPS0thj6ejz2Rv/wwILYn Yg/DTfxKRN4sInpG3qKDp5kxFTQRQAm6FzrK/YoNeQzl9dZPcm7lOpFhFEtHOowKvTKO qhMXImqmxJV6L1igF7pUQGvcxLiOnCjnFCOjaQE1AU4HUdAA3GfMjzcDyYPE4pS/XaeR /36A== X-Gm-Message-State: ACrzQf0yYPgtlgW/TdJF0v/OWC1IYZXiJ/CGVjcyETK2hpPaylwLKJFX tdZ6gwKfCI+jIlWs/Lpo+0tq+g== X-Google-Smtp-Source: AMsMyM4CHd0lOE8Rm/3v4PwlgRx/bBQe+7EooBJvnnY6/buIywrcVpw3hNDVZiC0kDU37vTvXNd06Q== X-Received: by 2002:a05:620a:4483:b0:6ce:8e57:254b with SMTP id x3-20020a05620a448300b006ce8e57254bmr1395661qkp.540.1663270633518; Thu, 15 Sep 2022 12:37:13 -0700 (PDT) Received: from abrestic-xps.ba.rivosinc.com (pool-71-105-112-35.nycmny.fios.verizon.net. [71.105.112.35]) by smtp.gmail.com with ESMTPSA id r1-20020ae9d601000000b006b872b606b1sm4596459qkk.128.2022.09.15.12.37.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Sep 2022 12:37:13 -0700 (PDT) From: Andrew Bresticker To: Palmer Dabbelt Cc: Paul Walmsley , Celeste Liu , dram , Ruizhe Pan , Conor.Dooley@microchip.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Bresticker Subject: [PATCH v4 0/2] Make mmap() with PROT_WRITE imply PROT_READ Date: Thu, 15 Sep 2022 15:37:00 -0400 Message-Id: <20220915193702.2201018-1-abrestic@rivosinc.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 2139619bcad7 ("riscv: mmap with PROT_WRITE but no PROT_READ is invalid") made mmap() reject mappings with only PROT_WRITE set in an attempt to fix an observed inconsistency in behavior when attempting to read from a PROT_WRITE-only mapping. The root cause of this behavior was actually that while RISC-V's protection_map maps VM_WRITE to readable PTE permissions (since write-only PTEs are considered reserved by the privileged spec), the page fault handler considered loads from VM_WRITE-only VMAs illegal accesses. Fix the underlying cause by handling faults in VM_WRITE-only VMAs (patch 1) and then re-enable use of mmap(PROT_WRITE) (patch 2), making RISC-V's behavior consistent with all other architectures that don't support write-only PTEs. Both patches are tagged as fixes for the aforementioned commit since that commit made a userspace visible change that will break any software relying on mmap(PROT_WRITE). (Also cc: stable since the offending commit was itself backported to stable). v1 -> v2: Allow handling of load faults in VM_WRITE VMAs v2 -> v3: Split into two pathces v3 -> v4: Fixes tags (+ this cover letter) Andrew Bresticker (2): riscv: Make VM_WRITE imply VM_READ riscv: Allow PROT_WRITE-only mmap() arch/riscv/kernel/sys_riscv.c | 3 --- arch/riscv/mm/fault.c | 3 ++- 2 files changed, 2 insertions(+), 4 deletions(-) -- 2.25.1