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050cf0d80f
The introduction of `portMEMORY_BARRIER` will ensure the places in the kernel use a barrier will work. For example, `xTaskResumeAll` has a memory barrier to ensure its correctness when compiled with optimization enabled. Without the barrier `xTaskResumeAll` can fail (e.g. start reading and writing to address 0 and/or infinite looping) when `xPendingReadyList` contains more than one task to restore. In `xTaskResumeAll` the compiler chooses to cache the `pxTCB` the first time through the loop for use in every subsequent loop. This is incorrect as the removal of `pxTCB->xEventListItem` will actually change the value of `pxTCB` if it was read again at the top of the loop. The barrier forces the compiler to read `pxTCB` again at the top of the loop. The compiler is operating correctly. The removal `pxTCB->xEventListItem` executes on a `List_t *` and `ListItem_t *`. This means that the compiler can assume that any `MiniListItem_t` values are unchanged by the loop (i.e. "strict-aliasing"). This allows the compiler to cache `pxTCB` as it is obtained via a `MiniListItem_t`. This is incorrect in this case because it is possible for a `ListItem_t *` to actually alias a `MiniListItem_t`. This is technically a "violation of aliasing rules" so we use the the barrier to disable the strict-aliasing optimization in this loop.
130 lines
5.4 KiB
C
130 lines
5.4 KiB
C
/*
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* FreeRTOS Kernel <DEVELOPMENT BRANCH>
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* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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#ifndef PORTMACRO_H
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#define PORTMACRO_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*-----------------------------------------------------------
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* Port specific definitions.
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*
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* The settings in this file configure FreeRTOS correctly for the
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* given hardware and compiler.
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*
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* These settings should not be altered.
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*-----------------------------------------------------------
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*/
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/* Type definitions. */
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#define portCHAR char
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#define portFLOAT float
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#define portDOUBLE double
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#define portLONG long
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#define portSHORT short
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#define portSTACK_TYPE uint32_t
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#define portBASE_TYPE long
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typedef portSTACK_TYPE StackType_t;
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typedef long BaseType_t;
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typedef unsigned long UBaseType_t;
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#if( configTICK_TYPE_WIDTH_IN_BITS == TICK_TYPE_WIDTH_16_BITS )
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typedef uint16_t TickType_t;
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#define portMAX_DELAY ( TickType_t ) 0xffff
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#elif ( configTICK_TYPE_WIDTH_IN_BITS == TICK_TYPE_WIDTH_32_BITS )
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typedef uint32_t TickType_t;
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#define portMAX_DELAY ( TickType_t ) 0xffffffffUL
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/* 32-bit tick type on a 32-bit architecture, so reads of the tick count do
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not need to be guarded with a critical section. */
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#define portTICK_TYPE_IS_ATOMIC 1
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#else
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#error configTICK_TYPE_WIDTH_IN_BITS set to unsupported tick type width.
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#endif
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/*-----------------------------------------------------------*/
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/* Interrupt control macros. */
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void microblaze_disable_interrupts( void );
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void microblaze_enable_interrupts( void );
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#define portDISABLE_INTERRUPTS() microblaze_disable_interrupts()
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#define portENABLE_INTERRUPTS() microblaze_enable_interrupts()
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/*-----------------------------------------------------------*/
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/* Critical section macros. */
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void vPortEnterCritical( void );
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void vPortExitCritical( void );
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#define portENTER_CRITICAL() { \
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extern UBaseType_t uxCriticalNesting; \
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microblaze_disable_interrupts(); \
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uxCriticalNesting++; \
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}
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#define portEXIT_CRITICAL() { \
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extern UBaseType_t uxCriticalNesting; \
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/* Interrupts are disabled, so we can */ \
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/* access the variable directly. */ \
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uxCriticalNesting--; \
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if( uxCriticalNesting == 0 ) \
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{ \
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/* The nesting has unwound and we \
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can enable interrupts again. */ \
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portENABLE_INTERRUPTS(); \
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} \
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}
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/*-----------------------------------------------------------*/
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/* Task utilities. */
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void vPortYield( void );
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#define portYIELD() vPortYield()
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void vTaskSwitchContext();
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#define portYIELD_FROM_ISR() vTaskSwitchContext()
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/*-----------------------------------------------------------*/
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/* Hardware specifics. */
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#define portBYTE_ALIGNMENT 4
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#define portSTACK_GROWTH ( -1 )
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#define portTICK_PERIOD_MS ( ( TickType_t ) 1000 / configTICK_RATE_HZ )
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#define portNOP() asm volatile ( "NOP" )
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#define portMEMORY_BARRIER() asm volatile ( "" ::: "memory" )
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/*-----------------------------------------------------------*/
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/* Task function macros as described on the FreeRTOS.org WEB site. */
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#define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )
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#define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )
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#ifdef __cplusplus
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}
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#endif
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#endif /* PORTMACRO_H */
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