115 lines
3.0 KiB
ArmAsm
115 lines
3.0 KiB
ArmAsm
/* exc_exit.S - ARM CORTEX-M3 exception/interrupt exit API */
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/*
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* Copyright (c) 2013-2014 Wind River Systems, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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DESCRIPTION
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Provides functions for performing kernel handling when exiting exceptions or
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interrupts that are installed directly in the vector table (i.e. that are not
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wrapped around by _isr_wrapper()).
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*/
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#define _ASMLANGUAGE
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#include <nano_private.h>
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#include <offsets.h>
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#include <toolchain.h>
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#include <arch/cpu.h>
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_ASM_FILE_PROLOGUE
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GTEXT(_ExcExit)
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GTEXT(_IntExit)
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GDATA(_nanokernel)
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#if CONFIG_GDB_INFO
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#define _EXIT_EXC_IF_FIBER_PREEMPTED beq _ExcExitWithGdbStub
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#else
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_EXIT_EXC_IF_FIBER_PREEMPTED: .macro
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it eq
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bxeq lr
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.endm
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#endif
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#define _EXIT_EXC_IF_FIBER_NOT_READY _EXIT_EXC_IF_FIBER_PREEMPTED
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/**
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*
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* @brief Kernel housekeeping when exiting interrupt handler installed
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* directly in vector table
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*
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* Kernel allows installing interrupt handlers (ISRs) directly into the vector
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* table to get the lowest interrupt latency possible. This allows the ISR to be
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* invoked directly without going through a software interrupt table. However,
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* upon exiting the ISR, some kernel work must still be performed, namely
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* possible context switching. While ISRs connected in the software interrupt
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* table do this automatically via a wrapper, ISRs connected directly in the
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* vector table must invoke _IntExit() as the *very last* action before
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* returning.
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*
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* e.g.
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*
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* void myISR(void)
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* {
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* printk("in %s\n", __FUNCTION__);
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* doStuff();
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* _IntExit();
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* }
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*
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* @return N/A
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*/
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SECTION_SUBSEC_FUNC(TEXT, _HandlerModeExit, _IntExit)
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/* _IntExit falls through to _ExcExit (they are aliases of each other) */
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/**
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*
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* @brief Kernel housekeeping when exiting exception handler installed
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* directly in vector table
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*
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* See _IntExit().
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*
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* @return N/A
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*/
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SECTION_SUBSEC_FUNC(TEXT, _HandlerModeExit, _ExcExit)
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ldr r1, =_nanokernel
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/* is the current thread preemptible (task) ? */
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ldr r2, [r1, #__tNANO_flags_OFFSET]
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ands.w r2, #PREEMPTIBLE
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_EXIT_EXC_IF_FIBER_PREEMPTED
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/* is there a fiber ready ? */
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ldr r2, [r1, #__tNANO_fiber_OFFSET]
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cmp r2, #0
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_EXIT_EXC_IF_FIBER_NOT_READY
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/* context switch required, pend the PendSV exception */
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ldr r1, =_SCS_ICSR
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ldr r2, =_SCS_ICSR_PENDSV
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str r2, [r1]
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_ExcExitWithGdbStub:
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_GDB_STUB_EXC_EXIT
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bx lr
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