text: /****************************************************************************
   * arch/misoc/src/minerva/minerva_usestack.c
   *
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.  The
   * ASF licenses this file to you 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.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <sched.h>
  #include <debug.h>
  
  #include <nuttx/kmalloc.h>
  #include <nuttx/arch.h>
  #include <nuttx/tls.h>
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_use_stack
   *
   * Description:
   *   Setup up stack-related information in the TCB using pre-allocated stack
   *   memory.  This function is called only from nxtask_init() when a task or
   *   kernel thread is started (never for pthreads).
   *
   *   The following TCB fields must be initialized:
   *
   *   - adj_stack_size: Stack size after adjustment for hardware,
   *     processor, etc.  This value is retained only for debug
   *     purposes.
   *   - stack_alloc_ptr: Pointer to allocated stack
   *   - adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
   *     initial value of the stack pointer.
   *
   * Input Parameters:
   *   - tcb: The TCB of new task
   *   - stack_size:  The allocated stack size.
   *
   *   NOTE:  Unlike up_stack_create() and up_stack_release, this function
   *   does not require the task type (ttype) parameter.  The TCB flags will
   *   always be set to provide the task type to up_use_stack() if it needs
   *   that information.
   *
   ****************************************************************************/
  
  int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
  {
    size_t top_of_stack;
    size_t size_of_stack;
  
  #ifdef CONFIG_TLS_ALIGNED
    /* Make certain that the user provided stack is properly aligned */
  
    DEBUGASSERT(((uintptr_t)stack & TLS_STACK_MASK) == 0);
  #endif
  
    /* Is there already a stack allocated? */
  
    if (tcb->stack_alloc_ptr)
      {
        /* Yes.. Release the old stack allocation */
  
        up_release_stack(tcb, tcb->flags & TCB_FLAG_TTYPE_MASK);
      }
  
    /* Save the new stack allocation */
  
    tcb->stack_alloc_ptr = stack;
  
    /* If stack debug is enabled, then fill the stack with a recognizable value
     * that we can use later to test for high water marks.
     */
  
  #ifdef CONFIG_STACK_COLORATION
    if (tcb->pid != 0)
      {
        memset(tcb->stack_alloc_ptr, 0xaa, stack_size);
      }
  #endif
  
    /* The i486 uses a push-down stack:  the stack grows toward loweraddresses
     * in memory.  The stack pointer register, points to the lowest, valid work
     * address (the "top" of the stack).  Items on the stack are referenced as
     * positive word offsets from sp.
     */
  
    top_of_stack = (uint32_t)tcb->stack_alloc_ptr + stack_size - 4;
  
    /* The i486 stack must be aligned at word (4 byte) boundaries. If necessary
     * top_of_stack must be rounded down to the next boundary
     */
  
    top_of_stack &= ~3;
    size_of_stack = top_of_stack - (uint32_t)tcb->stack_alloc_ptr + 4;
  
    /* Save the adjusted stack values in the struct tcb_s */
  
    tcb->adj_stack_ptr  = (uint32_t *)top_of_stack;
    tcb->adj_stack_size = size_of_stack;
  
    /* Initialize the TLS data structure */
  
    memset(tcb->stack_alloc_ptr, 0, sizeof(struct tls_info_s));
  
    return OK;
  }
  