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

[Jorge Ramirez <jorge.ramirez@oss.qualcomm.com>]

On 06/10/26 10:53:31, Harshal Dev wrote:
> Hi Jorge,
> 
> On 06-10-2026 02:31 am, Jorge Ramirez wrote:
> > On 05/10/26 21:42:24, Mukesh Ojha wrote:
> >> On Mon, Oct 05, 2026 at 02:54:00PM +0200, Jorge Ramirez-Ortiz wrote:
> >>> 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@oss.qualcomm.com>
> 
> Thanks for this patch, I was about to send one myself since I observed
> this on IQ10 as well.
> 
> >>> ---
> >>>  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;
> >>> +	}
> >>
> >>
> >> Earlier code was intentional please read the comment below.. /**...*/
> >>
> > 
> > AFAICS the comments say that the call might pass NULL and zero as input
> > resources. And this patch does exactly that - it doesnt allow NULL and
> > non-zero.
> >
> 
> I agree with this fix, it was strange to see a NULL pointer paired with non-zero table size.
> As the comment itself says, a NULL pointer + 0 size should be passed when the firmware binary
> does not have a resource table. This is also documented here in a separate comment:
> https://elixir.bootlin.com/linux/v7.3-rc5/source/drivers/firmware/qcom/qcom_pas.c#L131
> 
> I am validating this fix for Nord, expect a Tested-by tag from me today.


hi Harshal,

I have just sent a different fix that handles this case on the tee
backend instead (so that SCM backend is unaffected and can continue
implementing its underlying "null input pointer with a non-zero input
size 'protocol'"...the fact that a comment is needed should have meant
that a better more explicit abstraction should have been put in place
IMO ).

In any case, I have validated both patches on hardware with the TEE
backend. Probably safer to drop this one in favour of the other one.

Jorge