On 11/21/20 11:33 PM, Bjorn Andersson wrote: > On Fri 20 Nov 21:44 CST 2020, Suman Anna wrote: > >> On 11/20/20 9:38 PM, Bjorn Andersson wrote: >>> On Fri 20 Nov 21:01 CST 2020, Suman Anna 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 '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 deny the sysfs state/firmware/recovery change by >>>> introducing a state flag 'deny_sysfs_ops' that the individual >>>> remoteproc drivers can set based on their usage needs. The default >>>> behavior is to allow the sysfs operations as before. >>>> >>> >>> This makes sense, but can't we implement attribute_group->is_visible to >>> simply hide these entries from userspace instead of leaving them >>> "broken"? >> >> I would have to look into that, but can that be changed dynamically? >> Also, note that the enforcement is only on the writes/stores which impact >> the state-machine, but not the reads/shows. >> >> For PRU usecases, we will be setting this dynamically. >> > > It looks to be dynamic, but I don't know if there's any "caching" > involved. Please have a look and let me know. OK, will do. I can only check the week after though. regards Suman > > Regards, > Bjorn > >> regards >> Suman >> >>> >>> Regards, >>> Bjorn >>> >>>> Signed-off-by: Suman Anna <s-anna@xxxxxx> >>>> --- >>>> v2: revised to account for the 'recovery' sysfs file as well, patch >>>> description updated accordingly >>>> v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/20180915003725.17549-5-s-anna@xxxxxx/ >>>> >>>> drivers/remoteproc/remoteproc_sysfs.c | 12 ++++++++++++ >>>> include/linux/remoteproc.h | 2 ++ >>>> 2 files changed, 14 insertions(+) >>>> >>>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c >>>> index bd2950a246c9..3fd18a71c188 100644 >>>> --- a/drivers/remoteproc/remoteproc_sysfs.c >>>> +++ b/drivers/remoteproc/remoteproc_sysfs.c >>>> @@ -49,6 +49,10 @@ static ssize_t recovery_store(struct device *dev, >>>> { >>>> struct rproc *rproc = to_rproc(dev); >>>> >>>> + /* restrict sysfs operations if not allowed by remoteproc drivers */ >>>> + if (rproc->deny_sysfs_ops) >>>> + return -EPERM; >>>> + >>>> if (sysfs_streq(buf, "enabled")) { >>>> /* change the flag and begin the recovery process if needed */ >>>> rproc->recovery_disabled = false; >>>> @@ -158,6 +162,10 @@ static ssize_t firmware_store(struct device *dev, >>>> char *p; >>>> int err, len = count; >>>> >>>> + /* restrict sysfs operations if not allowed by remoteproc drivers */ >>>> + if (rproc->deny_sysfs_ops) >>>> + return -EPERM; >>>> + >>>> err = mutex_lock_interruptible(&rproc->lock); >>>> if (err) { >>>> dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, err); >>>> @@ -225,6 +233,10 @@ static ssize_t state_store(struct device *dev, >>>> struct rproc *rproc = to_rproc(dev); >>>> int ret = 0; >>>> >>>> + /* restrict sysfs operations if not allowed by remoteproc drivers */ >>>> + if (rproc->deny_sysfs_ops) >>>> + return -EPERM; >>>> + >>>> if (sysfs_streq(buf, "start")) { >>>> if (rproc->state == RPROC_RUNNING) >>>> return -EBUSY; >>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h >>>> index 3fa3ba6498e8..dbc3767f7d0e 100644 >>>> --- a/include/linux/remoteproc.h >>>> +++ b/include/linux/remoteproc.h >>>> @@ -508,6 +508,7 @@ struct rproc_dump_segment { >>>> * @has_iommu: flag to indicate if remote processor is behind an MMU >>>> * @auto_boot: flag to indicate if remote processor should be auto-started >>>> * @autonomous: true if an external entity has booted the remote processor >>>> + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery >>>> * @dump_segments: list of segments in the firmware >>>> * @nb_vdev: number of vdev currently handled by rproc >>>> * @char_dev: character device of the rproc >>>> @@ -545,6 +546,7 @@ struct rproc { >>>> bool has_iommu; >>>> bool auto_boot; >>>> bool autonomous; >>>> + bool deny_sysfs_ops; >>>> struct list_head dump_segments; >>>> int nb_vdev; >>>> u8 elf_class; >>>> -- >>>> 2.28.0 >>>> >>
