[PATCH v2 3/3] remoteproc: pru: Fix and cleanup firmware interrupt mapping logic

From: Suman Anna
Date: Wed Apr 07 2021 - 11:57:11 EST


The PRU firmware interrupt mappings are configured and unconfigured in
.start() and .stop() callbacks respectively using the variables 'evt_count'
and a 'mapped_irq' pointer. These variables are modified only during these
callbacks but are not re-initialized/reset properly during unwind or
failure paths. These stale values caused a kernel crash while stopping a
PRU remoteproc running a different firmware with no events on a subsequent
run after a previous run that was running a firmware with events.

Fix this crash by ensuring that the evt_count is 0 and the mapped_irq
pointer is set to NULL in pru_dispose_irq_mapping(). Also, reset these
variables properly during any failures in the .start() callback. While
at this, the pru_dispose_irq_mapping() callsites are all made to look
the same, moving any conditional logic to inside the function.

Fixes: c75c9fdac66e ("remoteproc: pru: Add support for PRU specific interrupt configuration")
Reported-by: Vignesh Raghavendra <vigneshr@xxxxxx>
Signed-off-by: Suman Anna <s-anna@xxxxxx>
---
v2:
- Fixed two additional cleanup paths in pru_handle_intrmap()
addressing Mathieu's review comment
v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/20210323223839.17464-4-s-anna@xxxxxx/

drivers/remoteproc/pru_rproc.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index 87b43976c51b..04863bf23db8 100644
--- a/drivers/remoteproc/pru_rproc.c
+++ b/drivers/remoteproc/pru_rproc.c
@@ -266,12 +266,17 @@ static void pru_rproc_create_debug_entries(struct rproc *rproc)

static void pru_dispose_irq_mapping(struct pru_rproc *pru)
{
- while (pru->evt_count--) {
+ if (!pru->mapped_irq)
+ return;
+
+ while (pru->evt_count) {
+ pru->evt_count--;
if (pru->mapped_irq[pru->evt_count] > 0)
irq_dispose_mapping(pru->mapped_irq[pru->evt_count]);
}

kfree(pru->mapped_irq);
+ pru->mapped_irq = NULL;
}

/*
@@ -307,8 +312,10 @@ static int pru_handle_intrmap(struct rproc *rproc)
pru->evt_count = rsc->num_evts;
pru->mapped_irq = kcalloc(pru->evt_count, sizeof(unsigned int),
GFP_KERNEL);
- if (!pru->mapped_irq)
+ if (!pru->mapped_irq) {
+ pru->evt_count = 0;
return -ENOMEM;
+ }

/*
* parse and fill in system event to interrupt channel and
@@ -317,13 +324,19 @@ static int pru_handle_intrmap(struct rproc *rproc)
* corresponding sibling PRUSS INTC node.
*/
parent = of_get_parent(dev_of_node(pru->dev));
- if (!parent)
+ if (!parent) {
+ kfree(pru->mapped_irq);
+ pru->mapped_irq = NULL;
+ pru->evt_count = 0;
return -ENODEV;
+ }

irq_parent = of_get_child_by_name(parent, "interrupt-controller");
of_node_put(parent);
if (!irq_parent) {
kfree(pru->mapped_irq);
+ pru->mapped_irq = NULL;
+ pru->evt_count = 0;
return -ENODEV;
}

@@ -398,8 +411,7 @@ static int pru_rproc_stop(struct rproc *rproc)
pru_control_write_reg(pru, PRU_CTRL_CTRL, val);

/* dispose irq mapping - new firmware can provide new mapping */
- if (pru->mapped_irq)
- pru_dispose_irq_mapping(pru);
+ pru_dispose_irq_mapping(pru);

return 0;
}
--
2.30.1