SPM: Allow entering the SP without needing a SMC

It may be needed to enter the Secure Partition through other means than
an MM_COMMUNICATE SMC. This patch enables this behaviour by extracting
the necessary code from mm_communicate() and allowing other parts of the
code to use it.

Change-Id: I59f6638d22d9c9d0baff0984f39d056298a8dc8e
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

include/services/spm_svc.h

@@ -74,6 +74,9 @@ uint64_t spm_smc_handler(uint32_t smc_fid,
 			 void *handle,
 			 uint64_t flags);
 
+/* Helper to enter a Secure Partition */
+uint64_t spm_sp_call(uint32_t smc_fid, uint64_t x1, uint64_t x2, uint64_t x3);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __SPM_SVC_H__ */

services/std_svc/spm/spm_main.c

@@ -180,6 +180,35 @@ int32_t spm_setup(void)
 	return 0;
 }
 
+/*******************************************************************************
+ * Function to perform a call to a Secure Partition.
+ ******************************************************************************/
+uint64_t spm_sp_call(uint32_t smc_fid, uint64_t x1, uint64_t x2, uint64_t x3)
+{
+	uint64_t rc;
+	sp_context_t *sp_ptr = &sp_ctx;
+
+	/* Wait until the Secure Partition is idle and set it to busy. */
+	sp_state_wait_switch(sp_ptr, SP_STATE_IDLE, SP_STATE_BUSY);
+
+	/* Set values for registers on SP entry */
+	cpu_context_t *cpu_ctx = &(sp_ptr->cpu_ctx);
+
+	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X0, smc_fid);
+	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X1, x1);
+	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X2, x2);
+	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X3, x3);
+
+	/* Jump to the Secure Partition. */
+	rc = spm_sp_synchronous_entry(sp_ptr);
+
+	/* Flag Secure Partition as idle. */
+	assert(sp_ptr->state == SP_STATE_BUSY);
+	sp_state_set(sp_ptr, SP_STATE_IDLE);
+
+	return rc;
+}
+
 /*******************************************************************************
  * MM_COMMUNICATE handler
  ******************************************************************************/
@@ -188,7 +217,6 @@ static uint64_t mm_communicate(uint32_t smc_fid, uint64_t mm_cookie,
 			       uint64_t comm_size_address, void *handle)
 {
 	uint64_t rc;
-	sp_context_t *ctx = &sp_ctx;
 
 	/* Cookie. Reserved for future use. It must be zero. */
 	if (mm_cookie != 0U) {
@@ -208,23 +236,8 @@ static uint64_t mm_communicate(uint32_t smc_fid, uint64_t mm_cookie,
 	/* Save the Normal world context */
 	cm_el1_sysregs_context_save(NON_SECURE);
 
-	/* Wait until the Secure Partition is idle and set it to busy. */
-	sp_state_wait_switch(ctx, SP_STATE_IDLE, SP_STATE_BUSY);
-
-	/* Set values for registers on SP entry */
-	cpu_context_t *cpu_ctx = &(ctx->cpu_ctx);
-
-	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X0, smc_fid);
-	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X1, comm_buffer_address);
-	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X2, comm_size_address);
-	write_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X3, plat_my_core_pos());
-
-	/* Jump to the Secure Partition. */
-	rc = spm_sp_synchronous_entry(ctx);
-
-	/* Flag Secure Partition as idle. */
-	assert(ctx->state == SP_STATE_BUSY);
-	sp_state_set(ctx, SP_STATE_IDLE);
+	rc = spm_sp_call(smc_fid, comm_buffer_address, comm_size_address,
+			 plat_my_core_pos());
 
 	/* Restore non-secure state */
 	cm_el1_sysregs_context_restore(NON_SECURE);