context_gcc.S
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/*
* Copyright (c) 2006-2022, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2006-09-15 QiuYi The first version
* 2006-10-09 Bernard add rt_hw_context_switch_to implementation
*/
/**
* @addtogroup ia32
*/
/*@{*/
/*
* void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
*/
.globl rt_hw_context_switch
rt_hw_context_switch:
pushfl /*pushed eflags*/
/*
* add by ssslady@gmail.com 2009-10-14
* When we return again the esp should no be change.
* The old code change the esp to esp-4 :-(.
* A protection fault maybe occure for img created by some compiler,eg.gcc in the fedor-11
* -------------------------------------------------------------------------
* entry old code new code
* EIP ->return esp EIP FLAGS ->return esp
* ... FLAGS ->retern esp CS
* CS EIP
* EIP
*/
popl %eax /*get flags*/
popl %ebx /*get eip*/
pushl %eax /*push flags*/
push %cs /*push cs*/
pushl %ebx /*push eip*/
/*-------------------------------------------------------------------
*/
/*push %cs*/ /*push cs register*/
/*pushl 0x8(%esp)*/ /*pushed eip register*/
pushl $0 /*fill irqno*/
push %ds /*push ds register*/
push %es /*push es register*/
pushal /*push eax,ecx,edx,ebx,esp,ebp,esp,edi registers*/
/*movl 0x40(%esp), %eax*/ /*to thread TCB*/
/*movl 0x3c(%esp), %ebx*/ /*from thread TCB*/
movl 0x3c(%esp), %eax /*to thread TCB*/
movl 0x38(%esp), %ebx /*from thread TCB*/
movl %esp, (%ebx) /*store esp in preempted tasks TCB*/
movl (%eax), %esp /*get new task stack pointer*/
popal /*restore new task TCB*/
pop %es
pop %ds
add $4,%esp /*skip irqno*/
iret
/*
* void rt_hw_context_switch_to(rt_uint32 to);
*/
.globl rt_hw_context_switch_to
rt_hw_context_switch_to:
push %ebp
movl %esp, %ebp
movl 0x8(%ebp), %eax /* to thread TCB */
movl (%eax), %esp /* get new task stack pointer */
popal /* restore new task TCB*/
pop %es
pop %ds
add $4, %esp /* skip irqno */
iret