| Message ID | 20190910160903.65694-6-swboyd@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Read-only memremap() | expand |
On Tue, Sep 10, 2019 at 9:09 AM Stephen Boyd <swboyd@chromium.org> wrote: > > The command DB is read-only already to the kernel because everything is > const marked once we map it. Let's go one step further and try to map > the memory as read-only in the page tables. This should make it harder > for random code to corrupt the database and change the contents. > > 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> > Cc: Dan Williams <dan.j.williams@intel.com> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> > Signed-off-by: Stephen Boyd <swboyd@chromium.org> > --- > drivers/soc/qcom/cmd-db.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c > index 10a34d26b753..6365e8260282 100644 > --- a/drivers/soc/qcom/cmd-db.c > +++ b/drivers/soc/qcom/cmd-db.c > @@ -240,7 +240,8 @@ static int cmd_db_dev_probe(struct platform_device *pdev) > { > int ret = 0; > > - cmd_db_header = devm_memremap_reserved_mem(&pdev->dev, MEMREMAP_WB); > + cmd_db_header = devm_memremap_reserved_mem(&pdev->dev, > + MEMREMAP_RO | MEMREMAP_WB); It seems weird to have both flags, like: "It's read-only, but if it ever did get written to somehow, make it writeback". > if (IS_ERR(cmd_db_header)) { > ret = PTR_ERR(cmd_db_header); > cmd_db_header = NULL; > -- > Sent by a computer through tubes >
diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c index 10a34d26b753..6365e8260282 100644 --- a/drivers/soc/qcom/cmd-db.c +++ b/drivers/soc/qcom/cmd-db.c @@ -240,7 +240,8 @@ static int cmd_db_dev_probe(struct platform_device *pdev) { int ret = 0; - cmd_db_header = devm_memremap_reserved_mem(&pdev->dev, MEMREMAP_WB); + cmd_db_header = devm_memremap_reserved_mem(&pdev->dev, + MEMREMAP_RO | MEMREMAP_WB); if (IS_ERR(cmd_db_header)) { ret = PTR_ERR(cmd_db_header); cmd_db_header = NULL;