[PATCH v1 16/16] misc: fastrpc: Add system unsigned PD support

[Ekansh Gupta]

Trusted CPU applications currently offload to signed PDs on CDSP to
gain some additional services provided by root PD. Unsigned PDs have
access to limited root PD services that may not be sufficient for
all use-cases. Signed PDs have a higher dynamic loading latency
which impacts the performance of applications. Limited root PD
services could be opened up for unsigned PDs but that should be
restricted for untrusted processes. For this requirement, System
unsigned PD is introduced which will be same as Unsigned PD for
most part but will have access to more root PD services. Add
changes to offload trusted applications to System unsigned PD
when unsigned offload is requested.

Signed-off-by: Ekansh Gupta <quic_ekangupt@xxxxxxxxxxx>
---
 drivers/misc/fastrpc.c      | 7 +++++++
 include/uapi/misc/fastrpc.h | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4aa4e36bebc3..2f893c94dcc8 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -2002,11 +2002,18 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
 	if (init.attrs & FASTRPC_MODE_UNSIGNED_MODULE)
 		fl->is_unsigned_pd = true;
 
+	/* Disregard any system unsigned PD attribute from userspace */
+	init.attrs &= (~FASTRPC_MODE_SYSTEM_UNSIGNED_PD);
+
 	if (is_session_rejected(fl, fl->is_unsigned_pd)) {
 		err = -EACCES;
 		goto err;
 	}
 
+	/* Trusted apps will be launched as system unsigned PDs */
+	if (!fl->untrusted_process && fl->is_unsigned_pd)
+		init.attrs |= FASTRPC_MODE_SYSTEM_UNSIGNED_PD;
+
 	if (init.filelen > INIT_FILELEN_MAX) {
 		err = -EINVAL;
 		goto err;
diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
index 7053a5b6b16b..d0fb01e7277d 100644
--- a/include/uapi/misc/fastrpc.h
+++ b/include/uapi/misc/fastrpc.h
@@ -63,6 +63,8 @@ enum fastrpc_proc_attr {
 	FASTRPC_MODE_SYSTEM_PROCESS	= (1 << 5),
 	/* Macro for Prvileged Process */
 	FASTRPC_MODE_PRIVILEGED		= (1 << 6),
+	/* Macro for system unsigned PD */
+	FASTRPC_MODE_SYSTEM_UNSIGNED_PD	= (1 << 17),
 };
 
 /* Fastrpc attribute for memory protection of buffers */
-- 
2.17.0