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Fri, 17 May 2019 09:47:50 -0700 (PDT) From: Stephen Boyd To: linux-kernel@vger.kernel.org Subject: [RFC/PATCH 0/5] Read-only memremap() proposal Date: Fri, 17 May 2019 09:47:41 -0700 Message-Id: <20190517164746.110786-1-swboyd@chromium.org> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190517_094752_036792_314FB4BB X-CRM114-Status: GOOD ( 11.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, Will Deacon , Andy Gross , Evan Green , Bjorn Andersson , Rob Herring , Catalin Marinas , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch series implements a read-only version of memremap() via a new MEMREMAP_RO flag. If this is passed in the mapping call, we'll try to map the memory region as read-only if it doesn't intersect with an existing mapping. Otherwise, we'll try to fallback to other flags to try to map the memory that way. The main use case I have is to map the command-db memory region on Qualcomm devices with a read-only mapping. It's already a const marked pointer and the API returns const pointers as well, so this series makes sure that even stray writes can't modify the memory. To get there we introduce a devm version of memremap() for a reserved memory region, add a memremap() flag, and implement support for that flag on arm64. Cc: Evan Green Cc: Rob Herring Cc: Bjorn Andersson Cc: Andy Gross Cc: Will Deacon Cc: Catalin Marinas Stephen Boyd (5): reserved_mem: Add a devm_memremap_reserved_mem() API soc: qcom: cmd-db: Migrate to devm_memremap_reserved_mem() memremap: Add support for read-only memory mappings arm64: Add support for arch_memremap_ro() soc: qcom: cmd-db: Map with read-only mappings arch/arm64/include/asm/io.h | 1 + drivers/of/of_reserved_mem.c | 45 +++++++++++++++++++++++++++++++++ drivers/soc/qcom/cmd-db.c | 14 +++------- include/linux/io.h | 1 + include/linux/of_reserved_mem.h | 6 +++++ kernel/iomem.c | 15 +++++++++-- 6 files changed, 70 insertions(+), 12 deletions(-) base-commit: 9e98c678c2d6ae3a17cb2de55d17f69dddaa231b prerequisite-patch-id: 62119e27c0c0686e02f0cb55c296b878fb7f5e47 prerequisite-patch-id: bda32cfc1733c245ae3f141d7c27b18e4adcc628 prerequisite-patch-id: b8f8097161bd15e87d54dcfbfa67b9ca1abc7204 -- Sent by a computer through tubes _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel