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SubjectRe: [RFC/PATCH 0/5] Read-only memremap() proposal
On Fri 17 May 09:47 PDT 2019, Stephen Boyd wrote:

> 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.
>

I have a few places where the first patch will be useful, and the rest
looks good.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

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

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