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/****************************************************************************
* arch/x86/src/i486/up_stackframe.c
*
* Copyright (C) 2013 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdint.h>
#include <sched.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <arch/irq.h>
#include "up_internal.h"
/****************************************************************************
* Pre-processor Macros
****************************************************************************/
/* The initial stack point is aligned at word (4 byte) boundaries. If
* necessary frame_size must be rounded up to the next boundary to retain
* this alignment.
*/
#define STACK_ALIGNMENT 4
/* Stack alignment macros */
#define STACK_ALIGN_MASK (STACK_ALIGNMENT-1)
#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
#define STACK_ALIGN_UP(a) (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: up_stack_frame
*
* Description:
* Allocate a stack frame in the TCB's stack to hold thread-specific data.
* This function may be called anytime after up_create_stack() or
* up_use_stack() have been called but before the task has been started.
*
* Thread data may be kept in the stack (instead of in the TCB) if it is
* accessed by the user code directly. This includes such things as
* argv[]. The stack memory is guaranteed to be in the same protection
* domain as the thread.
*
* The following TCB fields will be re-initialized:
*
* - adj_stack_size: Stack size after removal of the stack frame from
* the stack
* - adj_stack_ptr: Adjusted initial stack pointer after the frame has
* been removed from the stack. This will still be the initial value
* of the stack pointer when the task is started.
*
* Inputs:
* - tcb: The TCB of new task
* - frame_size: The size of the stack frame to allocate.
*
* Returned Value:
* - A pointer to bottom of the allocated stack frame. NULL will be
* returned on any failures. The alignment of the returned value is
* the same as the alignment of the stack itself.
*
****************************************************************************/
FAR void *up_stack_frame(FAR struct tcb_s *tcb, size_t frame_size)
{
uintptr_t topaddr;
/* Align the frame_size */
frame_size = STACK_ALIGN_UP(frame_size);
/* Is there already a stack allocated? Is it big enough? */
if (!tcb->stack_alloc_ptr || tcb->adj_stack_size <= frame_size)
{
return NULL;
}
/* Save the adjusted stack values in the struct tcb_s */
topaddr = (uintptr_t)tcb->adj_stack_ptr - frame_size;
tcb->adj_stack_ptr = (FAR void *)topaddr;
tcb->adj_stack_size -= frame_size;
/* Reset the initial stack pointer */
tcb->xcp.regs[REG_SP] = (uint32_t)tcb->adj_stack_ptr;
/* And return the pointer to the allocated region */
return (FAR void *)(topaddr + sizeof(uint32_t));
}
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