eduOS/arch/x86/include/asm/tasks.h

101 lines
3.1 KiB
C

/*
* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @author Stefan Lankes
* @file arch/x86/include/asm/tasks.h
* @brief Task related structure definitions
*
* This file contains the task_t structure definition
* and task state define constants
*/
#ifndef __ASM_TASKS_H__
#define __ASM_TASKS_H__
#include <eduos/stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Switch to current task
*
* @param stack Pointer to the old stack pointer
*/
void switch_context(size_t** stack);
/** @brief Setup a default frame for a new task
*
* @param task Pointer to the task structure
* @param ep The entry point for code execution
* @param arg Arguments list pointer for the task's stack
* @return
* - 0 on success
* - -EINVAL (-22) on failure
*/
int create_default_frame(task_t* task, entry_point_t ep, void* arg);
/** @brief Copy kernel stack pointer to TSS */
void set_kernel_stack(size_t stack);
/** @brief Register a task's TSS at GDT
*
* @return
* - 0 on success
*/
static inline int register_task(void)
{
uint16_t sel = 5 << 3;
asm volatile ("ltr %%ax" : : "a"(sel));
return 0;
}
/** @brief Jump back to user code
*
* This function runs the user code after stopping it just as if
* it was a return from a procedure.
*
* @return 0 in any case
*/
static inline int jump_to_user_code(uint32_t ep, uint32_t stack)
{
asm volatile ("mov %0, %%ds; mov %0, %%fs; mov %0, %%gs; mov %0, %%es" :: "r"(0x23));
asm volatile ("push $0x23; push %0; push $0x1B; push %1" :: "r"(stack), "r"(ep));
asm volatile ("lret" ::: "cc");
return 0;
}
#ifdef __cplusplus
}
#endif
#endif