fix(trp): preserve RMI SMC X4 when not used as return
This patch adds X2-X6 and 'smc_ret' parameters to trp_rmi_handler().
The last 'smc_ret' parameter passed in X7 contains address of
'trp_smc_result' structure on stack to return result of RMI SMC call.
This allows to preserve X4 if not used as a return argument as per
SMCCCv1.2. The patch also removes use of trp_args_t in RMI handling.
Signed-off-by: AlexeiFedorov <Alexei.Fedorov@arm.com>
Change-Id: I9e3387a7380b37863eeccc53d13e92e0ac5cffbd
diff --git a/services/std_svc/rmmd/trp/trp_entry.S b/services/std_svc/rmmd/trp/trp_entry.S
index 47c1df1..ae9f9aa 100644
--- a/services/std_svc/rmmd/trp/trp_entry.S
+++ b/services/std_svc/rmmd/trp/trp_entry.S
@@ -115,7 +115,29 @@
* ---------------------------------------------
*/
func trp_handler
+ /*
+ * Save Link Register and X4, as per SMCCC v1.2 its value
+ * must be preserved unless it contains result, as specified
+ * in the function definition.
+ */
+ stp x4, lr, [sp, #-16]!
+
+ /*
+ * Zero the space for X0-X3 in trp_smc_result structure
+ * and pass its address as the last argument.
+ */
+ stp xzr, xzr, [sp, #-16]!
+ stp xzr, xzr, [sp, #-16]!
+ mov x7, sp
+
bl trp_rmi_handler
- restore_args_call_smc
+
+ ldp x1, x2, [sp], #16
+ ldp x3, x4, [sp], #16
+ ldp x5, lr, [sp], #16
+
+ ldr x0, =RMM_RMI_REQ_COMPLETE
+ smc #0
+
b trp_handler
endfunc trp_handler