metalsvm/arch/x86/include/asm/tasks.h
2011-08-02 15:58:20 +02:00

99 lines
2.5 KiB
C

/*
* Copyright 2010 Stefan Lankes, Chair for Operating Systems,
* RWTH Aachen University
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of MetalSVM.
*
*/
/**
* @author Stefan Lankes
* @file arch/x86/include/asm/tasks.h
* @brief Task-related functions for forking and scheduling
*
* This file contains functions needed for task switching, scheduling and task creation.
*/
#ifndef __ARCH_TASKS__
#define __ARCH_TASKS__
#include <metalsvm/stddef.h>
#include <metalsvm/tasks_types.h>
#ifdef __cplusplus
extern "C" {
#endif
/** @brief Fork a task from current task
*
* @param task Pointer to the task structure to fork to
* @return
* - 0 on success
* - -EINVAL (-22) on failure
*/
int arch_fork(task_t* task);
/** @brieff Switch to new task
* @param id Task Id
*/
void switch_task(uint32_t id);
/** @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, internal_entry_point_t ep, void* arg);
/** @brief Register a task's TSS at GDT
*
* @param task Pointer to task structure
* @return
* - 0 on success
* - -EINVAL (-22) on failure
*/
int register_task(task_t* task);
/** @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");
return 0;
}
/** @brief determines the stack of a specific task
*
* @return start address of a specific task
*/
size_t get_stack(uint32_t id);
#ifdef __cplusplus
}
#endif
#endif