mirror of
https://github.com/apache/nuttx.git
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0e1b432dd0
reason:
svc call may trigger hardfault
Background
The origin of this issue is our desire to eliminate the function of storing
"regs" in g_current_regs and instead utilize (*running_task)->xcp.regs for storage.
The benefits of this approach include faster storage speed and
avoiding multiple accesses to g_current_regs during context switching,
thus ensuring that whether returning from an interrupt or an exception,
we consistently use this_task()->xcp.regs
Issue Encountered
However, when storing registers, we must ensure that (running_task)->xcp.regs is invalid
so that it can be safely overwritten.
According to the existing logic, the only scenario where (running_task)->xcp.regs
is valid is during restore_context. We must accurately identify this scenario.
Initially, we used the condition (running_task)==NULL for this purpose, but we deemed
this approach unsatisfactory as it did not align well with the actual logic.
(running_task) should not be NULL. Consequently, we adopted other arch-specific methods for judgment,
but due to special logic in some arch, the judgment was not accurate, leading to this issue.
Solution:
For armv6-m, we haven't found a more suitable solution, so we are sticking with (*running_task)==NULL.
For armv7-m/armv8-m, by removing support for primask, we can achieve accurate judgment.
PRIMASK is a design in armv6-m, that's why arm introduce BASEPRI from armv7-m.
It's wrong to provide this option for armv7-m/armv8-m arch.
Signed-off-by: hujun5 <hujun5@xiaomi.com>
78 lines
3.7 KiB
C
78 lines
3.7 KiB
C
/****************************************************************************
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* arch/arm/include/armv7-m/nvicpri.h
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __ARCH_ARM_INCLUDE_ARMV7_M_NVICPRI_H
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#define __ARCH_ARM_INCLUDE_ARMV7_M_NVICPRI_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <arch/chip/chip.h>
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/****************************************************************************
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* Pre-processor Prototypes
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****************************************************************************/
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/* In the normal cases, interrupts are not nest-able and all interrupts run
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* at an execution priority between NVIC_SYSH_PRIORITY_MIN and
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* NVIC_SYSH_PRIORITY_MAX (with NVIC_SYSH_PRIORITY_MAX reserved for SVCall).
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*
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* If, in addition, CONFIG_ARCH_HIPRI_INTERRUPT is defined, then special
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* high priority interrupts are supported. These are not "nested" in the
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* normal sense of the word. These high priority interrupts can interrupt
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* normal processing but execute outside of OS (although they can "get back
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* into the game" via a PendSV interrupt).
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*
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* In the normal course of things, interrupts must occasionally be disabled
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* using the up_irq_save() inline function to prevent contention in use of
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* resources that may be shared between interrupt level and non-interrupt
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* level logic. Now the question arises, if we are using
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* CONFIG_ARCH_HIPRI_INTERRUPT=y, do we disable all interrupts except
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* SVCall (we cannot disable SVCall interrupts). Or do we only disable the
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* "normal" interrupts?
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*
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* If we are using the BASEPRI register to disable interrupts, then the
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* answer is that we must disable ONLY the "normal interrupts". That
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* is because we cannot disable SVCALL interrupts and we cannot permit
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* SVCAll interrupts running at a higher priority than the high priority
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* interrupts (otherwise, they will introduce jitter in the high priority
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* interrupt response time.)
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*
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* Hence, if you need to disable the high priority interrupt, you will have
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* to disable the interrupt either at the peripheral that generates the
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* interrupt or at the NVIC. Disabling global interrupts via the BASEPRI
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* register cannot effect high priority interrupts.
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*/
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/* The high priority interrupt must be highest priority. This prevents
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* SVCALL handling from adding jitter to high priority interrupt response.
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* Disabling interrupts will disable all interrupts EXCEPT SVCALL and the
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* high priority interrupts.
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*/
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#define NVIC_SYSH_MAXNORMAL_PRIORITY NVIC_SYSH_PRIORITY_DEFAULT
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#define NVIC_SYSH_HIGH_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 2*NVIC_SYSH_PRIORITY_STEP)
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#define NVIC_SYSH_DISABLE_PRIORITY NVIC_SYSH_PRIORITY_DEFAULT
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#define NVIC_SYSH_SVCALL_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 1*NVIC_SYSH_PRIORITY_STEP)
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#endif /* __ARCH_ARM_INCLUDE_ARMV7_M_NVICPRI_H */
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