mirror of
https://github.com/apache/nuttx.git
synced 2026-08-27 12:20:46 +00:00
908df725ad
reason:
1 On different architectures, we can utilize more optimized strategies
to implement up_current_regs/up_set_current_regs.
eg. use interrupt registersor percpu registers.
code size
before
text data bss dec hex filename
262848 49985 63893 376726 5bf96 nuttx
after
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262844 49985 63893 376722 5bf92 nuttx
size change -4
Configuring NuttX and compile:
$ ./tools/configure.sh -l qemu-armv8a:nsh_smp
$ make
Running with qemu
$ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic \
-machine virt,virtualization=on,gic-version=3 \
-net none -chardev stdio,id=con,mux=on -serial chardev:con \
-mon chardev=con,mode=readline -kernel ./nuttx
Signed-off-by: hujun5 <hujun5@xiaomi.com>
103 lines
3.3 KiB
C
103 lines
3.3 KiB
C
/****************************************************************************
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* arch/arm/src/common/arm_switchcontext.c
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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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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sched.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include <nuttx/sched.h>
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#include "sched/sched.h"
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#include "group/group.h"
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#include "clock/clock.h"
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#include "arm_internal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_switch_context
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*
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* Description:
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* A task is currently in the ready-to-run list but has been prepped
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* to execute. Restore its context, and start execution.
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*
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* Input Parameters:
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* tcb: Refers to the head task of the ready-to-run list
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* which will be executed.
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* rtcb: Refers to the running task which will be blocked.
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*
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****************************************************************************/
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void up_switch_context(struct tcb_s *tcb, struct tcb_s *rtcb)
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{
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/* Update scheduler parameters */
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nxsched_suspend_scheduler(rtcb);
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/* Are we in an interrupt handler? */
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if (up_current_regs())
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{
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/* Yes, then we have to do things differently.
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* Just copy the current_regs into the OLD rtcb.
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*/
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arm_savestate(rtcb->xcp.regs);
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/* Update scheduler parameters */
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nxsched_resume_scheduler(tcb);
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/* Then switch contexts. Any necessary address environment
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* changes will be made when the interrupt returns.
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*/
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arm_restorestate(tcb->xcp.regs);
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}
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/* No, then we will need to perform the user context switch */
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else
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{
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/* Update scheduler parameters */
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nxsched_resume_scheduler(tcb);
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/* Switch context to the context of the task at the head of the
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* ready to run list.
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*/
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arm_switchcontext(&rtcb->xcp.regs, tcb->xcp.regs);
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/* arm_switchcontext forces a context switch to the task at the
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* head of the ready-to-run list. It does not 'return' in the
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* normal sense. When it does return, it is because the blocked
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* task is again ready to run and has execution priority.
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*/
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}
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}
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