89 lines
3.2 KiB
C
89 lines
3.2 KiB
C
/*
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* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <eduos/stdio.h>
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#include <eduos/stdlib.h>
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#include <eduos/string.h>
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#include <eduos/tasks.h>
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#include <eduos/errno.h>
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#include <eduos/processor.h>
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size_t* get_current_stack(void)
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{
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task_t* curr_task = current_task;
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return curr_task->last_stack_pointer;
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}
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int create_default_frame(task_t* task, entry_point_t ep, void* arg)
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{
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size_t *stack;
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struct state *stptr;
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size_t state_size;
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if (BUILTIN_EXPECT(!task, 0))
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return -EINVAL;
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if (BUILTIN_EXPECT(!task->stack, 0))
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return -EINVAL;
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memset(task->stack, 0xCD, KERNEL_STACK_SIZE);
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/* The difference between setting up a task for SW-task-switching
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* and not for HW-task-switching is setting up a stack and not a TSS.
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* This is the stack which will be activated and popped off for iret later.
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*/
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stack = (size_t*) (task->stack + KERNEL_STACK_SIZE - 16); // => stack is 16byte aligned
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/* Only marker for debugging purposes, ... */
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*stack-- = 0xDEADBEEF;
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/* the first-function-to-be-called's arguments, ... */
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*stack-- = (size_t) arg;
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/* and the "caller" we shall return to.
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* This procedure cleans the task after exit. */
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*stack = (size_t) leave_kernel_task;
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/* Next bunch on the stack is the initial register state.
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* The stack must look like the stack of a task which was
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* scheduled away previously. */
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state_size = sizeof(struct state);
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stack = (size_t*) ((size_t) stack - state_size);
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stptr = (struct state *) stack;
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memset(stptr, 0x00, state_size);
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stptr->esp = (size_t)stack + state_size;
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stptr->eip = (size_t)ep;
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stptr->eflags = 0x1202;
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/* Set the task's stack pointer entry to the stack we have crafted right now. */
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task->last_stack_pointer = (size_t*)stack;
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return 0;
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}
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