services/spd/opteed/opteed_main.c

/*
 * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */


/*******************************************************************************
 * This is the Secure Payload Dispatcher (SPD). The dispatcher is meant to be a
 * plug-in component to the Secure Monitor, registered as a runtime service. The
 * SPD is expected to be a functional extension of the Secure Payload (SP) that
 * executes in Secure EL1. The Secure Monitor will delegate all SMCs targeting
 * the Trusted OS/Applications range to the dispatcher. The SPD will either
 * handle the request locally or delegate it to the Secure Payload. It is also
 * responsible for initialising and maintaining communication with the SP.
 ******************************************************************************/
#include <arch_helpers.h>
#include <assert.h>
#include <bl31.h>
#include <bl_common.h>
#include <context_mgmt.h>
#include <debug.h>
#include <errno.h>
#include <platform.h>
#include <runtime_svc.h>
#include <stddef.h>
#include <uuid.h>
#include "opteed_private.h"
#include "teesmc_opteed.h"
#include "teesmc_opteed_macros.h"


/*******************************************************************************
 * Address of the entrypoint vector table in OPTEE. It is
 * initialised once on the primary core after a cold boot.
 ******************************************************************************/
optee_vectors_t *optee_vectors;

/*******************************************************************************
 * Array to keep track of per-cpu OPTEE state
 ******************************************************************************/
optee_context_t opteed_sp_context[OPTEED_CORE_COUNT];
uint32_t opteed_rw;



static int32_t opteed_init(void);

/*******************************************************************************
 * This function is the handler registered for S-EL1 interrupts by the
 * OPTEED. It validates the interrupt and upon success arranges entry into
 * the OPTEE at 'optee_fiq_entry()' for handling the interrupt.
 ******************************************************************************/
static uint64_t opteed_sel1_interrupt_handler(uint32_t id,
					    uint32_t flags,
					    void *handle,
					    void *cookie)
{
	uint32_t linear_id;
	optee_context_t *optee_ctx;

	/* Check the security state when the exception was generated */
	assert(get_interrupt_src_ss(flags) == NON_SECURE);

	/* Sanity check the pointer to this cpu's context */
	assert(handle == cm_get_context(NON_SECURE));

	/* Save the non-secure context before entering the OPTEE */
	cm_el1_sysregs_context_save(NON_SECURE);

	/* Get a reference to this cpu's OPTEE context */
	linear_id = plat_my_core_pos();
	optee_ctx = &opteed_sp_context[linear_id];
	assert(&optee_ctx->cpu_ctx == cm_get_context(SECURE));

	cm_set_elr_el3(SECURE, (uint64_t)&optee_vectors->fiq_entry);
	cm_el1_sysregs_context_restore(SECURE);
	cm_set_next_eret_context(SECURE);

	/*
	 * Tell the OPTEE that it has to handle an FIQ (synchronously).
	 * Also the instruction in normal world where the interrupt was
	 * generated is passed for debugging purposes. It is safe to
	 * retrieve this address from ELR_EL3 as the secure context will
	 * not take effect until el3_exit().
	 */
	SMC_RET1(&optee_ctx->cpu_ctx, read_elr_el3());
}

/*******************************************************************************
 * OPTEE Dispatcher setup. The OPTEED finds out the OPTEE entrypoint and type
 * (aarch32/aarch64) if not already known and initialises the context for entry
 * into OPTEE for its initialization.
 ******************************************************************************/
int32_t opteed_setup(void)
{
	entry_point_info_t *optee_ep_info;
	uint32_t linear_id;

	linear_id = plat_my_core_pos();

	/*
	 * Get information about the Secure Payload (BL32) image. Its
	 * absence is a critical failure.  TODO: Add support to
	 * conditionally include the SPD service
	 */
	optee_ep_info = bl31_plat_get_next_image_ep_info(SECURE);
	if (!optee_ep_info) {
		WARN("No OPTEE provided by BL2 boot loader, Booting device"
			" without OPTEE initialization. SMC`s destined for OPTEE"
			" will return SMC_UNK\n");
		return 1;
	}

	/*
	 * If there's no valid entry point for SP, we return a non-zero value
	 * signalling failure initializing the service. We bail out without
	 * registering any handlers
	 */
	if (!optee_ep_info->pc)
		return 1;

	/*
	 * We could inspect the SP image and determine it's execution
	 * state i.e whether AArch32 or AArch64. Assuming it's AArch32
	 * for the time being.
	 */
	opteed_rw = OPTEE_AARCH64;
	opteed_init_optee_ep_state(optee_ep_info,
				opteed_rw,
				optee_ep_info->pc,
				&opteed_sp_context[linear_id]);

	/*
	 * All OPTEED initialization done. Now register our init function with
	 * BL31 for deferred invocation
	 */
	bl31_register_bl32_init(&opteed_init);

	return 0;
}

/*******************************************************************************
 * This function passes control to the OPTEE image (BL32) for the first time
 * on the primary cpu after a cold boot. It assumes that a valid secure
 * context has already been created by opteed_setup() which can be directly
 * used.  It also assumes that a valid non-secure context has been
 * initialised by PSCI so it does not need to save and restore any
 * non-secure state. This function performs a synchronous entry into
 * OPTEE. OPTEE passes control back to this routine through a SMC.
 ******************************************************************************/
static int32_t opteed_init(void)
{
	uint32_t linear_id = plat_my_core_pos();
	optee_context_t *optee_ctx = &opteed_sp_context[linear_id];
	entry_point_info_t *optee_entry_point;
	uint64_t rc;

	/*
	 * Get information about the OPTEE (BL32) image. Its
	 * absence is a critical failure.
	 */
	optee_entry_point = bl31_plat_get_next_image_ep_info(SECURE);
	assert(optee_entry_point);

	cm_init_my_context(optee_entry_point);

	/*
	 * Arrange for an entry into OPTEE. It will be returned via
	 * OPTEE_ENTRY_DONE case
	 */
	rc = opteed_synchronous_sp_entry(optee_ctx);
	assert(rc != 0);

	return rc;
}


/*******************************************************************************
 * This function is responsible for handling all SMCs in the Trusted OS/App
 * range from the non-secure state as defined in the SMC Calling Convention
 * Document. It is also responsible for communicating with the Secure
 * payload to delegate work and return results back to the non-secure
 * state. Lastly it will also return any information that OPTEE needs to do
 * the work assigned to it.
 ******************************************************************************/
uint64_t opteed_smc_handler(uint32_t smc_fid,
			 uint64_t x1,
			 uint64_t x2,
			 uint64_t x3,
			 uint64_t x4,
			 void *cookie,
			 void *handle,
			 uint64_t flags)
{
	cpu_context_t *ns_cpu_context;
	uint32_t linear_id = plat_my_core_pos();
	optee_context_t *optee_ctx = &opteed_sp_context[linear_id];
	uint64_t rc;

	/*
	 * Determine which security state this SMC originated from
	 */

	if (is_caller_non_secure(flags)) {
		/*
		 * This is a fresh request from the non-secure client.
		 * The parameters are in x1 and x2. Figure out which
		 * registers need to be preserved, save the non-secure
		 * state and send the request to the secure payload.
		 */
		assert(handle == cm_get_context(NON_SECURE));

		cm_el1_sysregs_context_save(NON_SECURE);

		/*
		 * We are done stashing the non-secure context. Ask the
		 * OPTEE to do the work now.
		 */

		/*
		 * Verify if there is a valid context to use, copy the
		 * operation type and parameters to the secure context
		 * and jump to the fast smc entry point in the secure
		 * payload. Entry into S-EL1 will take place upon exit
		 * from this function.
		 */
		assert(&optee_ctx->cpu_ctx == cm_get_context(SECURE));

		/* Set appropriate entry for SMC.
		 * We expect OPTEE to manage the PSTATE.I and PSTATE.F
		 * flags as appropriate.
		 */
		if (GET_SMC_TYPE(smc_fid) == SMC_TYPE_FAST) {
			cm_set_elr_el3(SECURE, (uint64_t)
					&optee_vectors->fast_smc_entry);
		} else {
			cm_set_elr_el3(SECURE, (uint64_t)
					&optee_vectors->yield_smc_entry);
		}

		cm_el1_sysregs_context_restore(SECURE);
		cm_set_next_eret_context(SECURE);

		write_ctx_reg(get_gpregs_ctx(&optee_ctx->cpu_ctx),
			      CTX_GPREG_X4,
			      read_ctx_reg(get_gpregs_ctx(handle),
					   CTX_GPREG_X4));
		write_ctx_reg(get_gpregs_ctx(&optee_ctx->cpu_ctx),
			      CTX_GPREG_X5,
			      read_ctx_reg(get_gpregs_ctx(handle),
					   CTX_GPREG_X5));
		write_ctx_reg(get_gpregs_ctx(&optee_ctx->cpu_ctx),
			      CTX_GPREG_X6,
			      read_ctx_reg(get_gpregs_ctx(handle),
					   CTX_GPREG_X6));
		/* Propagate hypervisor client ID */
		write_ctx_reg(get_gpregs_ctx(&optee_ctx->cpu_ctx),
			      CTX_GPREG_X7,
			      read_ctx_reg(get_gpregs_ctx(handle),
					   CTX_GPREG_X7));

		SMC_RET4(&optee_ctx->cpu_ctx, smc_fid, x1, x2, x3);
	}

	/*
	 * Returning from OPTEE
	 */

	switch (smc_fid) {
	/*
	 * OPTEE has finished initialising itself after a cold boot
	 */
	case TEESMC_OPTEED_RETURN_ENTRY_DONE:
		/*
		 * Stash the OPTEE entry points information. This is done
		 * only once on the primary cpu
		 */
		assert(optee_vectors == NULL);
		optee_vectors = (optee_vectors_t *) x1;

		if (optee_vectors) {
			set_optee_pstate(optee_ctx->state, OPTEE_PSTATE_ON);

			/*
			 * OPTEE has been successfully initialized.
			 * Register power management hooks with PSCI
			 */
			psci_register_spd_pm_hook(&opteed_pm);

			/*
			 * Register an interrupt handler for S-EL1 interrupts
			 * when generated during code executing in the
			 * non-secure state.
			 */
			flags = 0;
			set_interrupt_rm_flag(flags, NON_SECURE);
			rc = register_interrupt_type_handler(INTR_TYPE_S_EL1,
						opteed_sel1_interrupt_handler,
						flags);
			if (rc)
				panic();
		}

		/*
		 * OPTEE reports completion. The OPTEED must have initiated
		 * the original request through a synchronous entry into
		 * OPTEE. Jump back to the original C runtime context.
		 */
		opteed_synchronous_sp_exit(optee_ctx, x1);


	/*
	 * These function IDs is used only by OP-TEE to indicate it has
	 * finished:
	 * 1. turning itself on in response to an earlier psci
	 *    cpu_on request
	 * 2. resuming itself after an earlier psci cpu_suspend
	 *    request.
	 */
	case TEESMC_OPTEED_RETURN_ON_DONE:
	case TEESMC_OPTEED_RETURN_RESUME_DONE:


	/*
	 * These function IDs is used only by the SP to indicate it has
	 * finished:
	 * 1. suspending itself after an earlier psci cpu_suspend
	 *    request.
	 * 2. turning itself off in response to an earlier psci
	 *    cpu_off request.
	 */
	case TEESMC_OPTEED_RETURN_OFF_DONE:
	case TEESMC_OPTEED_RETURN_SUSPEND_DONE:
	case TEESMC_OPTEED_RETURN_SYSTEM_OFF_DONE:
	case TEESMC_OPTEED_RETURN_SYSTEM_RESET_DONE:

		/*
		 * OPTEE reports completion. The OPTEED must have initiated the
		 * original request through a synchronous entry into OPTEE.
		 * Jump back to the original C runtime context, and pass x1 as
		 * return value to the caller
		 */
		opteed_synchronous_sp_exit(optee_ctx, x1);

	/*
	 * OPTEE is returning from a call or being preempted from a call, in
	 * either case execution should resume in the normal world.
	 */
	case TEESMC_OPTEED_RETURN_CALL_DONE:
		/*
		 * This is the result from the secure client of an
		 * earlier request. The results are in x0-x3. Copy it
		 * into the non-secure context, save the secure state
		 * and return to the non-secure state.
		 */
		assert(handle == cm_get_context(SECURE));
		cm_el1_sysregs_context_save(SECURE);

		/* Get a reference to the non-secure context */
		ns_cpu_context = cm_get_context(NON_SECURE);
		assert(ns_cpu_context);

		/* Restore non-secure state */
		cm_el1_sysregs_context_restore(NON_SECURE);
		cm_set_next_eret_context(NON_SECURE);

		SMC_RET4(ns_cpu_context, x1, x2, x3, x4);

	/*
	 * OPTEE has finished handling a S-EL1 FIQ interrupt. Execution
	 * should resume in the normal world.
	 */
	case TEESMC_OPTEED_RETURN_FIQ_DONE:
		/* Get a reference to the non-secure context */
		ns_cpu_context = cm_get_context(NON_SECURE);
		assert(ns_cpu_context);

		/*
		 * Restore non-secure state. There is no need to save the
		 * secure system register context since OPTEE was supposed
		 * to preserve it during S-EL1 interrupt handling.
		 */
		cm_el1_sysregs_context_restore(NON_SECURE);
		cm_set_next_eret_context(NON_SECURE);

		SMC_RET0((uint64_t) ns_cpu_context);

	default:
		panic();
	}
}

/* Define an OPTEED runtime service descriptor for fast SMC calls */
DECLARE_RT_SVC(
	opteed_fast,

	OEN_TOS_START,
	OEN_TOS_END,
	SMC_TYPE_FAST,
	opteed_setup,
	opteed_smc_handler
);

/* Define an OPTEED runtime service descriptor for yielding SMC calls */
DECLARE_RT_SVC(
	opteed_std,

	OEN_TOS_START,
	OEN_TOS_END,
	SMC_TYPE_YIELD,
	NULL,
	opteed_smc_handler
);