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. Signed-off-by: Suman Anna <[email protected]> --- v2: revised to account for the 'recovery' sysfs file as well, patch description updated accordingly v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/[email protected]/ 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
