linux-kernel - [PATCH v3 0/5] Read-only memremap()

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Message-Id: <20190910160903.65694-1-swboyd@chromium.org>
Date:   Tue, 10 Sep 2019 09:08:58 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        Evan Green <evgreen@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH v3 0/5] Read-only memremap()

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.

Changes from v2 (https://lkml.kernel.org/r/20190614203717.75479-1-swboyd@chromium.org):
 * Added a comment to kerneldoc for the new MEMREMAP_RO flag
 * Rebased to v5.3-rc1

Changes from v1:
 * Picked up tags and rebased to v5.2-rc3

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

Cc: Evan Green <evgreen@...omium.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: Andy Gross <agross@...nel.org>
Cc: Will Deacon <will.deacon@....com>
Cc: Catalin Marinas <catalin.marinas@....com>

 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                  | 20 ++++++++++++---
 6 files changed, 74 insertions(+), 13 deletions(-)


base-commit: 5f9e832c137075045d15cd6899ab0505cfb2ca4b
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