remoteproc: pru: Fix and cleanup firmware interrupt mapping logic

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.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Fixes: c75c9fdac66e ("remoteproc: pru: Add support for PRU specific interrupt configuration")
Reported-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Link: https://lore.kernel.org/r/20210407155641.5501-4-s-anna@ti.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index ac6348c..b13ff42 100644 (file)
--- 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;
 }