On Thu 17 Feb 21:00 PST 2022, Kishon Vijay Abraham I wrote:
>
>
> On 16/02/22 1:42 pm, Puranjay Mohan wrote:
> > The remoteproc framework provides sysfs interfaces for changing
> > the firmware name and for starting/stopping a remote processor
> > through the sysfs files 'state' and 'firmware'. The 'coredump'
> > file is used to set the coredump configuration. The 'recovery'
> > sysfs file can also be used similarly to control the error recovery
> > state machine of a remoteproc. These interfaces are currently
> > allowed irrespective of how the remoteprocs were booted (like
> > remoteproc self auto-boot, remoteproc client-driven boot etc).
> > These interfaces can adversely affect a remoteproc and its clients
> > especially when a remoteproc is being controlled by a remoteproc
> > client driver(s). Also, not all remoteproc drivers may want to
> > support the sysfs interfaces by default.
> >
> > Add support to make the remoteproc sysfs files read only by
> > introducing a state flag 'sysfs_read_only' that the individual
> > remoteproc drivers can set based on their usage needs. The default
> > behavior is to allow the sysfs operations as before.
> >
> > Implement attribute_group->is_visible() to make the sysfs
> > entries read only when 'sysfs_read_only' flag is set.
> >
> > Signed-off-by: Puranjay Mohan <p-mohan@xxxxxx>
> > Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > ---
> > Changes in v4->v5:
> > Rename deny_sysfs_ops to sysfs_read_only.
> > Make coredump readonly with other files.
> >
> > Changes in v3->v4:
> > Use mode = 0444 in rproc_is_visible() to make the sysfs entries
> > read-only when the deny_sysfs_ops flag is set.
> > ---
> > drivers/remoteproc/remoteproc_sysfs.c | 19 ++++++++++++++++++-
> > include/linux/remoteproc.h | 2 ++
> > 2 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> > index ea8b89f97d7b..abf0cd05d5e1 100644
> > --- a/drivers/remoteproc/remoteproc_sysfs.c
> > +++ b/drivers/remoteproc/remoteproc_sysfs.c
> > @@ -230,6 +230,22 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
> > }
> > static DEVICE_ATTR_RO(name);
> >
> > +static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr,
> > + int n)
> > +{
> > + struct device *dev = kobj_to_dev(kobj);
> > + struct rproc *rproc = to_rproc(dev);
> > + umode_t mode = attr->mode;
> > +
> > + if (rproc->sysfs_read_only && (attr == &dev_attr_recovery.attr ||
> > + attr == &dev_attr_firmware.attr ||
> > + attr == &dev_attr_state.attr ||
> > + attr == &dev_attr_coredump.attr))
> > + mode = 0444;
>
> Nitpick: use S_IRUGO instead of 0444.
>
Thanks for the suggestion Kishon, but I like 0444, it has direct meaning
to me.
So unless there's some directive to use S_I*** throughout the kernel I
would prefer this.
Regards,
Bjorn
> Thanks,
> Kishon
> > +
> > + return mode;
> > +}
> > +
> > static struct attribute *rproc_attrs[] = {
> > &dev_attr_coredump.attr,
> > &dev_attr_recovery.attr,
> > @@ -240,7 +256,8 @@ static struct attribute *rproc_attrs[] = {
> > };
> >
> > static const struct attribute_group rproc_devgroup = {
> > - .attrs = rproc_attrs
> > + .attrs = rproc_attrs,
> > + .is_visible = rproc_is_visible,
> > };
> >
> > static const struct attribute_group *rproc_devgroups[] = {
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > index e0600e1e5c17..93a1d0050fbc 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -523,6 +523,7 @@ struct rproc_dump_segment {
> > * @table_sz: size of @cached_table
> > * @has_iommu: flag to indicate if remote processor is behind an MMU
> > * @auto_boot: flag to indicate if remote processor should be auto-started
> > + * @sysfs_read_only: flag to make remoteproc sysfs files read only
> > * @dump_segments: list of segments in the firmware
> > * @nb_vdev: number of vdev currently handled by rproc
> > * @elf_class: firmware ELF class
> > @@ -562,6 +563,7 @@ struct rproc {
> > size_t table_sz;
> > bool has_iommu;
> > bool auto_boot;
> > + bool sysfs_read_only;
> > struct list_head dump_segments;
> > int nb_vdev;
> > u8 elf_class;
> >
