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TSPD: Explicitly allow NS preemption for Yielding SMCs 

When EL3 exception handling is in effect (i.e.,
EL3_EXCEPTION_HANDLING=1), Non-secure interrupts can't preempt Secure
execution. However, for yielding SMCs, preemption by Non-secure
interupts is intended.

This patch therefore adds a call to ehf_allow_ns_preemption() before
dispatching a Yielding SMC to TSP.

Change-Id: Ia3a1ae252f3adc0f14e6d7e0502f251bdb349bdf
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
This commit is contained in:
Jeenu Viswambharan 2018-01-10 15:22:49 +00:00
parent 26ea390891
commit 1dd022ca6a
1 changed files with 21 additions and 2 deletions
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23
services/spd/tspd/tspd_main.c
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
* Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@ -20,6 +20,7 @@
#include <bl_common.h>
#include <context_mgmt.h>
#include <debug.h>
#include <ehf.h>
#include <errno.h>
#include <platform.h>
#include <runtime_svc.h>
@ -540,6 +541,18 @@ uint64_t tspd_smc_handler(uint32_t smc_fid,
*/
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.
*/
ehf_allow_ns_preemption();
#endif
}
cm_el1_sysregs_context_restore(SECURE);
@ -646,7 +659,13 @@ uint64_t tspd_smc_handler(uint32_t smc_fid,
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.
*/
ehf_allow_ns_preemption();
#endif
/* We just need to return to the preempted point in
* TSP and the execution will resume as normal.