[PATCH] remoteproc: qcom: pas: pass no resource table when the firmware has none

[Jorge Ramirez-Ortiz]

The firmware resource table is passed to the PAS backend even when the
firmware carries none. This only works on the first boot, while the
cached pointer and its size are both zero.

Stopping the remote processor, or failing to start it, frees the cached
table and clears the pointer but leaves the size set. The next start
then pairs a NULL table with a non-zero size.

The SCM backend substitutes an empty table and hides the problem. The
TEE backend copies from the NULL pointer:

  remoteproc remoteproc2: powering up cdsp
  pc : __pi_memcpy_generic+0x110/0x22c
  lr : qcom_pas_tee_get_rsc_table+0xf4/0x25c
  Call trace:
   __pi_memcpy_generic+0x110/0x22c (P)
   qcom_pas_get_rsc_table+0x38/0x60
   qcom_pas_parse_firmware+0xa0/0x100
   rproc_boot+0x2d4/0x380
   state_store+0x40/0x100

Fixes: a4584bff63c8 ("remoteproc: pas: Extend parse_fw callback to fetch resources via SMC call")
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez@xxxxxxxxxxxxxxxx>
---
 drivers/remoteproc/qcom_q6v5_pas.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
index a005546c265d..e871e03ba794 100644
--- a/drivers/remoteproc/qcom_q6v5_pas.c
+++ b/drivers/remoteproc/qcom_q6v5_pas.c
@@ -463,7 +463,7 @@ static int qcom_pas_parse_firmware(struct rproc *rproc, const struct firmware *f
 	struct resource_table *table = NULL;
 	size_t output_rt_size;
 	void *output_rt;
-	size_t table_sz;
+	size_t table_sz = 0;
 	int ret;
 
 	ret = qcom_register_dump_segments(rproc, fw);
@@ -476,11 +476,12 @@ static int qcom_pas_parse_firmware(struct rproc *rproc, const struct firmware *f
 		return 0;
 
 	ret = rproc_elf_load_rsc_table(rproc, fw);
-	if (ret)
+	if (ret) {
 		dev_dbg(&rproc->dev, "Failed to load resource table from firmware\n");
-
-	table = rproc->table_ptr;
-	table_sz = rproc->table_sz;
+	} else {
+		table = rproc->table_ptr;
+		table_sz = rproc->table_sz;
+	}
 
 	/*
 	 * The resources consumed by Qualcomm remote processors fall into two categories:
-- 
2.54.0