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af34cd72ca
When a Yielding SMC is preempted, it's possible that Non-secure world is resumed afterwards. In this case, Non-secure execution would find itself in a state where the SMC has returned. However, the dispatcher might not get an opportunity to populate the corrected return code for having been preempted, and therefore the caller of the Yielding SMC cannot reliably determine whether the SMC had successfully completed or had been preempted. To solve this, this patch introduces a new parameter to the ehf_allow_ns_preemption() API. An SPD, through this parameter, would provide the expected error code when a Yielding SMC is preempted. EHF can then populate the specified value in x0 of the Non-secure context so that the caller of the Yielding SMC correctly identifies the SMC return as a preemption. Documentation updates to follow. Change-Id: Ia9c3f8f03f9d72d81aa235eaae2ee0374b972e1e Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
91 lines
2.6 KiB
C
91 lines
2.6 KiB
C
/*
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* Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#ifndef __EHF_H__
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#define __EHF_H__
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#ifndef __ASSEMBLY__
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#include <stdint.h>
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#include <utils_def.h>
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/* Valid priorities set bit 0 of the priority handler. */
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#define _EHF_PRI_VALID (((uintptr_t) 1) << 0)
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/* Marker for no handler registered for a valid priority */
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#define _EHF_NO_HANDLER (0 | _EHF_PRI_VALID)
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/* Extract the specified number of top bits from 7 lower bits of priority */
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#define EHF_PRI_TO_IDX(pri, plat_bits) \
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((pri & 0x7f) >> (7 - plat_bits))
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/* Install exception priority descriptor at a suitable index */
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#define EHF_PRI_DESC(plat_bits, priority) \
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[EHF_PRI_TO_IDX(priority, plat_bits)] = { \
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.ehf_handler = _EHF_NO_HANDLER, \
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}
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/* Macro for platforms to regiter its exception priorities */
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#define EHF_REGISTER_PRIORITIES(priorities, num, bits) \
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const ehf_priorities_t exception_data = { \
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.num_priorities = num, \
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.ehf_priorities = priorities, \
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.pri_bits = bits, \
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}
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/*
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* Priority stack, managed as a bitmap.
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*
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* Currently only supports 32 priority levels, allowing platforms to use up to 5
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* top bits of priority. But the type can be changed to uint64_t should need
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* arise to support 64 priority levels, allowing platforms to use up to 6 top
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* bits of priority.
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*/
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typedef uint32_t ehf_pri_bits_t;
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/*
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* Per-PE exception data. The data for each PE is kept as a per-CPU data field.
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* See cpu_data.h.
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*/
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typedef struct {
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ehf_pri_bits_t active_pri_bits;
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/* Priority mask value before any priority levels were active */
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uint8_t init_pri_mask;
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/* Non-secure priority mask value stashed during Secure execution */
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uint8_t ns_pri_mask;
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} __aligned(sizeof(uint64_t)) pe_exc_data_t;
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typedef int (*ehf_handler_t)(uint32_t intr_raw, uint32_t flags, void *handle,
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void *cookie);
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typedef struct ehf_pri_desc {
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/*
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* 4-byte-aligned exception handler. Bit 0 indicates the corresponding
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* priority level is valid. This is effectively of ehf_handler_t type,
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* but left as uintptr_t in order to make pointer arithmetic convenient.
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*/
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uintptr_t ehf_handler;
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} ehf_pri_desc_t;
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typedef struct ehf_priorities {
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ehf_pri_desc_t *ehf_priorities;
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unsigned int num_priorities;
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int pri_bits;
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} ehf_priorities_t;
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void ehf_init(void);
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void ehf_activate_priority(unsigned int priority);
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void ehf_deactivate_priority(unsigned int priority);
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void ehf_register_priority_handler(unsigned int pri, ehf_handler_t handler);
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void ehf_allow_ns_preemption(uint64_t preempt_ret_code);
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unsigned int ehf_is_ns_preemption_allowed(void);
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#endif /* __ASSEMBLY__ */
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#endif /* __EHF_H__ */
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