/* * Copyright (c) 2013-2022, 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include "tspd_private.h" /******************************************************************************* * Address of the entrypoint vector table in the Secure Payload. It is * initialised once on the primary core after a cold boot. ******************************************************************************/ tsp_vectors_t *tsp_vectors; /******************************************************************************* * Array to keep track of per-cpu Secure Payload state ******************************************************************************/ tsp_context_t tspd_sp_context[TSPD_CORE_COUNT]; /* TSP UID */ DEFINE_SVC_UUID2(tsp_uuid, 0xa056305b, 0x9132, 0x7b42, 0x98, 0x11, 0x71, 0x68, 0xca, 0x50, 0xf3, 0xfa); int32_t tspd_init(void); /* * This helper function handles Secure EL1 preemption. The preemption could be * due Non Secure interrupts or EL3 interrupts. In both the cases we context * switch to the normal world and in case of EL3 interrupts, it will again be * routed to EL3 which will get handled at the exception vectors. */ uint64_t tspd_handle_sp_preemption(void *handle) { cpu_context_t *ns_cpu_context; 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); /* * To allow Secure EL1 interrupt handler to re-enter TSP while TSP * is preempted, the secure system register context which will get * overwritten must be additionally saved. This is currently done * by the TSPD S-EL1 interrupt handler. */ /* * Restore non-secure state. */ cm_el1_sysregs_context_restore(NON_SECURE); cm_set_next_eret_context(NON_SECURE); /* * The TSP was preempted during execution of a Yielding SMC Call. * Return back to the normal world with SMC_PREEMPTED as error * code in x0. */ SMC_RET1(ns_cpu_context, SMC_PREEMPTED); } /******************************************************************************* * This function is the handler registered for S-EL1 interrupts by the TSPD. It * validates the interrupt and upon success arranges entry into the TSP at * 'tsp_sel1_intr_entry()' for handling the interrupt. * Typically, interrupts for a specific security state get handled in the same * security execption level if the execution is in the same security state. For * example, if a non-secure interrupt gets fired when CPU is executing in NS-EL2 * it gets handled in the non-secure world. * However, interrupts belonging to the opposite security state typically demand * a world(context) switch. This is inline with the security principle which * states a secure interrupt has to be handled in the secure world. * Hence, the TSPD in EL3 expects the context(handle) for a secure interrupt to * be non-secure and vice versa. * However, a race condition between non-secure and secure interrupts can lead to * a scenario where the above assumptions do not hold true. This is demonstrated * below through Note 1. ******************************************************************************/ static uint64_t tspd_sel1_interrupt_handler(uint32_t id, uint32_t flags, void *handle, void *cookie) { uint32_t linear_id; tsp_context_t *tsp_ctx; /* Get a reference to this cpu's TSP context */ linear_id = plat_my_core_pos(); tsp_ctx = &tspd_sp_context[linear_id]; #if TSP_NS_INTR_ASYNC_PREEMPT /* * Note 1: * Under the current interrupt routing model, interrupts from other * world are routed to EL3 when TSP_NS_INTR_ASYNC_PREEMPT is enabled. * Consider the following scenario: * 1/ A non-secure payload(like tftf) requests a secure service from * TSP by invoking a yielding SMC call. * 2/ Later, execution jumps to TSP in S-EL1 with the help of TSP * Dispatcher in Secure Monitor(EL3). * 3/ While CPU is executing TSP, a Non-secure interrupt gets fired. * this demands a context switch to the non-secure world through * secure monitor. * 4/ Consequently, TSP in S-EL1 get asynchronously pre-empted and * execution switches to secure monitor(EL3). * 5/ EL3 tries to triage the (Non-secure) interrupt based on the * highest pending interrupt. * 6/ However, while the NS Interrupt was pending, secure timer gets * fired which makes a S-EL1 interrupt to be pending. * 7/ Hence, execution jumps to this companion handler of S-EL1 * interrupt (i.e., tspd_sel1_interrupt_handler) even though the TSP * was pre-empted due to non-secure interrupt. * 8/ The above sequence of events explain how TSP was pre-empted by * S-EL1 interrupt indirectly in an asynchronous way. * 9/ Hence, we track the TSP pre-emption by S-EL1 interrupt using a * boolean variable per each core. * 10/ This helps us to indicate that SMC call for TSP service was * pre-empted when execution resumes in non-secure world. */ /* Check the security state when the exception was generated */ if (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 TSP */ cm_el1_sysregs_context_save(NON_SECURE); tsp_ctx->preempted_by_sel1_intr = false; } else { /* Sanity check the pointer to this cpu's context */ assert(handle == cm_get_context(SECURE)); /* Save the secure context before entering the TSP for S-EL1 * interrupt handling */ cm_el1_sysregs_context_save(SECURE); tsp_ctx->preempted_by_sel1_intr = true; } #else /* 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 TSP */ cm_el1_sysregs_context_save(NON_SECURE); #endif assert(&tsp_ctx->cpu_ctx == cm_get_context(SECURE)); /* * Determine if the TSP was previously preempted. Its last known * context has to be preserved in this case. * The TSP should return control to the TSPD after handling this * S-EL1 interrupt. Preserve essential EL3 context to allow entry into * the TSP at the S-EL1 interrupt entry point using the 'cpu_context' * structure. There is no need to save the secure system register * context since the TSP is supposed to preserve it during S-EL1 * interrupt handling. */ if (get_yield_smc_active_flag(tsp_ctx->state)) { tsp_ctx->saved_spsr_el3 = (uint32_t)SMC_GET_EL3(&tsp_ctx->cpu_ctx, CTX_SPSR_EL3); tsp_ctx->saved_elr_el3 = SMC_GET_EL3(&tsp_ctx->cpu_ctx, CTX_ELR_EL3); #if TSP_NS_INTR_ASYNC_PREEMPT memcpy(&tsp_ctx->sp_ctx, &tsp_ctx->cpu_ctx, TSPD_SP_CTX_SIZE); #endif } cm_el1_sysregs_context_restore(SECURE); cm_set_elr_spsr_el3(SECURE, (uint64_t) &tsp_vectors->sel1_intr_entry, SPSR_64(MODE_EL1, MODE_SP_ELX, DISABLE_ALL_EXCEPTIONS)); cm_set_next_eret_context(SECURE); /* * Tell the TSP that it has to handle a S-EL1 interrupt 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_RET2(&tsp_ctx->cpu_ctx, TSP_HANDLE_SEL1_INTR_AND_RETURN, read_elr_el3()); } #if TSP_NS_INTR_ASYNC_PREEMPT /******************************************************************************* * This function is the handler registered for Non secure interrupts by the * TSPD. It validates the interrupt and upon success arranges entry into the * normal world for handling the interrupt. ******************************************************************************/ static uint64_t tspd_ns_interrupt_handler(uint32_t id, uint32_t flags, void *handle, void *cookie) { /* Check the security state when the exception was generated */ assert(get_interrupt_src_ss(flags) == SECURE); /* * Disable the routing of NS interrupts from secure world to EL3 while * interrupted on this core. */ disable_intr_rm_local(INTR_TYPE_NS, SECURE); return tspd_handle_sp_preemption(handle); } #endif /******************************************************************************* * Secure Payload Dispatcher setup. The SPD finds out the SP entrypoint and type * (aarch32/aarch64) if not already known and initialises the context for entry * into the SP for its initialisation. ******************************************************************************/ static int32_t tspd_setup(void) { entry_point_info_t *tsp_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 */ tsp_ep_info = bl31_plat_get_next_image_ep_info(SECURE); if (!tsp_ep_info) { WARN("No TSP provided by BL2 boot loader, Booting device" " without TSP initialization. SMC`s destined for TSP" " 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 (!tsp_ep_info->pc) return 1; /* * We could inspect the SP image and determine its execution * state i.e whether AArch32 or AArch64. Assuming it's AArch64 * for the time being. */ tspd_init_tsp_ep_state(tsp_ep_info, TSP_AARCH64, tsp_ep_info->pc, &tspd_sp_context[linear_id]); #if TSP_INIT_ASYNC bl31_set_next_image_type(SECURE); #else /* * All TSPD initialization done. Now register our init function with * BL31 for deferred invocation */ bl31_register_bl32_init(&tspd_init); #endif return 0; } /******************************************************************************* * This function passes control to the Secure Payload 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 tspd_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 the Secure payload. The SP passes control * back to this routine through a SMC. ******************************************************************************/ int32_t tspd_init(void) { uint32_t linear_id = plat_my_core_pos(); tsp_context_t *tsp_ctx = &tspd_sp_context[linear_id]; entry_point_info_t *tsp_entry_point; uint64_t rc; /* * Get information about the Secure Payload (BL32) image. Its * absence is a critical failure. */ tsp_entry_point = bl31_plat_get_next_image_ep_info(SECURE); assert(tsp_entry_point); cm_init_my_context(tsp_entry_point); /* * Arrange for an entry into the test secure payload. It will be * returned via TSP_ENTRY_DONE case */ rc = tspd_synchronous_sp_entry(tsp_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 the secure payload needs to do the * work assigned to it. ******************************************************************************/ static uintptr_t tspd_smc_handler(uint32_t smc_fid, u_register_t x1, u_register_t x2, u_register_t x3, u_register_t x4, void *cookie, void *handle, u_register_t flags) { cpu_context_t *ns_cpu_context; uint32_t linear_id = plat_my_core_pos(), ns; tsp_context_t *tsp_ctx = &tspd_sp_context[linear_id]; uint64_t rc; #if TSP_INIT_ASYNC entry_point_info_t *next_image_info; #endif /* Determine which security state this SMC originated from */ ns = is_caller_non_secure(flags); switch (smc_fid) { /* * This function ID is used by TSP to indicate that it was * preempted by a normal world IRQ. * */ case TSP_PREEMPTED: if (ns) SMC_RET1(handle, SMC_UNK); return tspd_handle_sp_preemption(handle); /* * This function ID is used only by the TSP to indicate that it has * finished handling a S-EL1 interrupt or was preempted by a higher * priority pending EL3 interrupt. Execution should resume * in the normal world. */ case TSP_HANDLED_S_EL1_INTR: if (ns) SMC_RET1(handle, SMC_UNK); assert(handle == cm_get_context(SECURE)); /* * Restore the relevant EL3 state which saved to service * this SMC. */ if (get_yield_smc_active_flag(tsp_ctx->state)) { SMC_SET_EL3(&tsp_ctx->cpu_ctx, CTX_SPSR_EL3, tsp_ctx->saved_spsr_el3); SMC_SET_EL3(&tsp_ctx->cpu_ctx, CTX_ELR_EL3, tsp_ctx->saved_elr_el3); #if TSP_NS_INTR_ASYNC_PREEMPT /* * Need to restore the previously interrupted * secure context. */ memcpy(&tsp_ctx->cpu_ctx, &tsp_ctx->sp_ctx, TSPD_SP_CTX_SIZE); #endif } /* 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 the TSP was supposed * to preserve it during S-EL1 interrupt handling. */ cm_el1_sysregs_context_restore(NON_SECURE); cm_set_next_eret_context(NON_SECURE); /* Refer to Note 1 in function tspd_sel1_interrupt_handler()*/ #if TSP_NS_INTR_ASYNC_PREEMPT if (tsp_ctx->preempted_by_sel1_intr) { /* Reset the flag */ tsp_ctx->preempted_by_sel1_intr = false; SMC_RET1(ns_cpu_context, SMC_PREEMPTED); } else { SMC_RET0((uint64_t) ns_cpu_context); } #else SMC_RET0((uint64_t) ns_cpu_context); #endif /* * This function ID is used only by the SP to indicate it has * finished initialising itself after a cold boot */ case TSP_ENTRY_DONE: if (ns) SMC_RET1(handle, SMC_UNK); /* * Stash the SP entry points information. This is done * only once on the primary cpu */ assert(tsp_vectors == NULL); tsp_vectors = (tsp_vectors_t *) x1; if (tsp_vectors) { set_tsp_pstate(tsp_ctx->state, TSP_PSTATE_ON); /* * TSP has been successfully initialized. Register power * management hooks with PSCI */ psci_register_spd_pm_hook(&tspd_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, tspd_sel1_interrupt_handler, flags); if (rc) panic(); #if TSP_NS_INTR_ASYNC_PREEMPT /* * Register an interrupt handler for NS interrupts when * generated during code executing in secure state are * routed to EL3. */ flags = 0; set_interrupt_rm_flag(flags, SECURE); rc = register_interrupt_type_handler(INTR_TYPE_NS, tspd_ns_interrupt_handler, flags); if (rc) panic(); /* * Disable the NS interrupt locally. */ disable_intr_rm_local(INTR_TYPE_NS, SECURE); #endif } #if TSP_INIT_ASYNC /* Save the Secure EL1 system register context */ assert(cm_get_context(SECURE) == &tsp_ctx->cpu_ctx); cm_el1_sysregs_context_save(SECURE); /* Program EL3 registers to enable entry into the next EL */ next_image_info = bl31_plat_get_next_image_ep_info(NON_SECURE); assert(next_image_info); assert(NON_SECURE == GET_SECURITY_STATE(next_image_info->h.attr)); cm_init_my_context(next_image_info); cm_prepare_el3_exit(NON_SECURE); SMC_RET0(cm_get_context(NON_SECURE)); #else /* * SP reports completion. The SPD must have initiated * the original request through a synchronous entry * into the SP. Jump back to the original C runtime * context. */ tspd_synchronous_sp_exit(tsp_ctx, x1); break; #endif /* * This function ID is used only by the SP to indicate it has finished * aborting a preempted Yielding SMC Call. */ case TSP_ABORT_DONE: /* * These function IDs are used only by the SP 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 TSP_ON_DONE: case TSP_RESUME_DONE: /* * These function IDs are 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 TSP_OFF_DONE: case TSP_SUSPEND_DONE: case TSP_SYSTEM_OFF_DONE: case TSP_SYSTEM_RESET_DONE: if (ns) SMC_RET1(handle, SMC_UNK); /* * SP reports completion. The SPD must have initiated the * original request through a synchronous entry into the SP. * Jump back to the original C runtime context, and pass x1 as * return value to the caller */ tspd_synchronous_sp_exit(tsp_ctx, x1); break; /* * Request from non-secure client to perform an * arithmetic operation or response from secure * payload to an earlier request. */ case TSP_FAST_FID(TSP_ADD): case TSP_FAST_FID(TSP_SUB): case TSP_FAST_FID(TSP_MUL): case TSP_FAST_FID(TSP_DIV): case TSP_YIELD_FID(TSP_ADD): case TSP_YIELD_FID(TSP_SUB): case TSP_YIELD_FID(TSP_MUL): case TSP_YIELD_FID(TSP_DIV): /* * Request from non-secure client to perform a check * of the DIT PSTATE bit. */ case TSP_YIELD_FID(TSP_CHECK_DIT): if (ns) { /* * 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)); /* Check if we are already preempted */ if (get_yield_smc_active_flag(tsp_ctx->state)) SMC_RET1(handle, SMC_UNK); cm_el1_sysregs_context_save(NON_SECURE); /* Save x1 and x2 for use by TSP_GET_ARGS call below */ store_tsp_args(tsp_ctx, x1, x2); /* * We are done stashing the non-secure context. Ask the * secure payload 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(&tsp_ctx->cpu_ctx == cm_get_context(SECURE)); /* Set appropriate entry for SMC. * We expect the TSP 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) &tsp_vectors->fast_smc_entry); } else { set_yield_smc_active_flag(tsp_ctx->state); cm_set_elr_el3(SECURE, (uint64_t) &tsp_vectors->yield_smc_entry); #if TSP_NS_INTR_ASYNC_PREEMPT /* * Enable the routing of NS interrupts to EL3 * during processing of a Yielding SMC Call on * this core. */ enable_intr_rm_local(INTR_TYPE_NS, SECURE); #endif #if EL3_EXCEPTION_HANDLING /* * With EL3 exception handling, while an SMC is * being processed, Non-secure interrupts can't * preempt Secure execution. However, for * yielding SMCs, we want preemption to happen; * so explicitly allow NS preemption in this * case, and supply the preemption return code * for TSP. */ ehf_allow_ns_preemption(TSP_PREEMPTED); #endif } cm_el1_sysregs_context_restore(SECURE); cm_set_next_eret_context(SECURE); SMC_RET3(&tsp_ctx->cpu_ctx, smc_fid, x1, x2); } else { /* * This is the result from the secure client of an * earlier request. The results are in x1-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); if (GET_SMC_TYPE(smc_fid) == SMC_TYPE_YIELD) { clr_yield_smc_active_flag(tsp_ctx->state); #if TSP_NS_INTR_ASYNC_PREEMPT /* * Disable the routing of NS interrupts to EL3 * after processing of a Yielding SMC Call on * this core is finished. */ disable_intr_rm_local(INTR_TYPE_NS, SECURE); #endif } SMC_RET3(ns_cpu_context, x1, x2, x3); } assert(0); /* Unreachable */ /* * Request from the non-secure world to abort a preempted Yielding SMC * Call. */ case TSP_FID_ABORT: /* ABORT should only be invoked by normal world */ if (!ns) { assert(0); break; } assert(handle == cm_get_context(NON_SECURE)); cm_el1_sysregs_context_save(NON_SECURE); /* Abort the preempted SMC request */ if (!tspd_abort_preempted_smc(tsp_ctx)) { /* * If there was no preempted SMC to abort, return * SMC_UNK. * * Restoring the NON_SECURE context is not necessary as * the synchronous entry did not take place if the * return code of tspd_abort_preempted_smc is zero. */ cm_set_next_eret_context(NON_SECURE); break; } cm_el1_sysregs_context_restore(NON_SECURE); cm_set_next_eret_context(NON_SECURE); SMC_RET1(handle, SMC_OK); /* * Request from non secure world to resume the preempted * Yielding SMC Call. */ case TSP_FID_RESUME: /* RESUME should be invoked only by normal world */ if (!ns) { assert(0); break; } /* * This is a resume request from the non-secure client. * save the non-secure state and send the request to * the secure payload. */ assert(handle == cm_get_context(NON_SECURE)); /* Check if we are already preempted before resume */ if (!get_yield_smc_active_flag(tsp_ctx->state)) SMC_RET1(handle, SMC_UNK); cm_el1_sysregs_context_save(NON_SECURE); /* * We are done stashing the non-secure context. Ask the * secure payload to do the work now. */ #if TSP_NS_INTR_ASYNC_PREEMPT /* * Enable the routing of NS interrupts to EL3 during resumption * of a Yielding SMC Call on this core. */ enable_intr_rm_local(INTR_TYPE_NS, SECURE); #endif #if EL3_EXCEPTION_HANDLING /* * Allow the resumed yielding SMC processing to be preempted by * Non-secure interrupts. Also, supply the preemption return * code for TSP. */ ehf_allow_ns_preemption(TSP_PREEMPTED); #endif /* We just need to return to the preempted point in * TSP and the execution will resume as normal. */ cm_el1_sysregs_context_restore(SECURE); cm_set_next_eret_context(SECURE); SMC_RET0(&tsp_ctx->cpu_ctx); /* * This is a request from the secure payload for more arguments * for an ongoing arithmetic operation requested by the * non-secure world. Simply return the arguments from the non- * secure client in the original call. */ case TSP_GET_ARGS: if (ns) SMC_RET1(handle, SMC_UNK); get_tsp_args(tsp_ctx, x1, x2); SMC_RET2(handle, x1, x2); case TOS_CALL_COUNT: /* * Return the number of service function IDs implemented to * provide service to non-secure */ SMC_RET1(handle, TSP_NUM_FID); case TOS_UID: /* Return TSP UID to the caller */ SMC_UUID_RET(handle, tsp_uuid); case TOS_CALL_VERSION: /* Return the version of current implementation */ SMC_RET2(handle, TSP_VERSION_MAJOR, TSP_VERSION_MINOR); default: break; } SMC_RET1(handle, SMC_UNK); } /* Define a SPD runtime service descriptor for fast SMC calls */ DECLARE_RT_SVC( tspd_fast, OEN_TOS_START, OEN_TOS_END, SMC_TYPE_FAST, tspd_setup, tspd_smc_handler ); /* Define a SPD runtime service descriptor for Yielding SMC Calls */ DECLARE_RT_SVC( tspd_std, OEN_TOS_START, OEN_TOS_END, SMC_TYPE_YIELD, NULL, tspd_smc_handler );