Re: [PATCH 10/39] Annotate hardware config module parameters in drivers/iio/

[William Breathitt Gray]

On Thu, Dec 01, 2016 at 12:30:55PM +0000, David Howells wrote:
>When the kernel is running in secure boot mode, we lock down the kernel to
>prevent userspace from modifying the running kernel image.  Whilst this
>includes prohibiting access to things like /dev/mem, it must also prevent
>access by means of configuring driver modules in such a way as to cause a
>device to access or modify the kernel image.
>
>To this end, annotate module_param* statements that refer to hardware
>configuration and indicate for future reference what type of parameter they
>specify.  The parameter parser in the core sees this information and can
>skip such parameters with an error message if the kernel is locked down.
>The module initialisation then runs as normal, but just sees whatever the
>default values for those parameters is.
>
>Note that we do still need to do the module initialisation because some
>drivers have viable defaults set in case parameters aren't specified and
>some drivers support automatic configuration (e.g. PNP or PCI) in addition
>to manually coded parameters.
>
>This patch annotates drivers in drivers/iio/.
>
>Suggested-by: One Thousand Gnomes <gnomes@xxxxxxxxxxxxxxxxxxx>
>Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
>cc: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
>cc: Jonathan Cameron <jic23@xxxxxxxxxx>
>cc: linux-iio@xxxxxxxxxxxxxxx

Acked-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>

>---
>
> drivers/iio/adc/stx104.c  |    2 +-
> drivers/iio/dac/cio-dac.c |    2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c
>index 7e3645749eaf..a805bd543acb 100644
>--- a/drivers/iio/adc/stx104.c
>+++ b/drivers/iio/adc/stx104.c
>@@ -49,7 +49,7 @@
> 
> static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
> static unsigned int num_stx104;
>-module_param_array(base, uint, &num_stx104, 0);
>+module_param_hw_array(base, uint, ioport, &num_stx104, 0);
> MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
> 
> /**
>diff --git a/drivers/iio/dac/cio-dac.c b/drivers/iio/dac/cio-dac.c
>index 5a743e2a779d..dac086129edf 100644
>--- a/drivers/iio/dac/cio-dac.c
>+++ b/drivers/iio/dac/cio-dac.c
>@@ -39,7 +39,7 @@
> 
> static unsigned int base[max_num_isa_dev(CIO_DAC_EXTENT)];
> static unsigned int num_cio_dac;
>-module_param_array(base, uint, &num_cio_dac, 0);
>+module_param_hw_array(base, uint, ioport, &num_cio_dac, 0);
> MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
> 
> /**
>