nuttx/arch/arm/include/tls.h

/****************************************************************************
 * arch/arm/include/tls.h
 *
 *   Copyright (C) 2016 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.
 *
 ****************************************************************************/

#ifndef __ARCH_ARM_INCLUDE_TLS_H
#define __ARCH_ARM_INCLUDE_TLS_H 1

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <assert.h>
#include <nuttx/arch.h>
#include <nuttx/tls.h>

#ifdef CONFIG_TLS

/****************************************************************************
 * Inline Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_getsp
 ****************************************************************************/

/* I don't know if the builtin to get SP is enabled */

static inline uint32_t up_getsp(void)
{
  uint32_t sp;
  __asm__
  (
    "\tmov %0, sp\n\t"
    : "=r"(sp)
  );

  return sp;
}

/****************************************************************************
 * Name: up_tls_info
 *
 * Description:
 *   Return the TLS information structure for the currently executing thread.
 *   When TLS is enabled, up_createstack() will align allocated stacks to
 *   the TLS_STACK_ALIGN value.  An instance of the following structure will
 *   be implicitly positioned at the "lower" end of the stack.  Assuming a
 *   "push down" stack, this is at the "far" end of the stack (and can be
 *   clobbered if the stack overflows).
 *
 *   If an MCU has a "push up" then that TLS structure will lie at the top
 *   of the stack and stack allocation and initialization logic must take
 *   care to preserve this structure content.
 *
 *   The stack memory is fully accessible to user mode threads.
 *
 * Input Parameters:
 *   None
 *
 * Returned Value:
 *   A pointer to TLS info structure at the beginning of the STACK memory
 *   allocation.  This is essentially an application of the TLS_INFO(sp)
 *   macro and has a platform dependency only in the manner in which the
 *   stack pointer (sp) is obtained and interpreted.
 *
 ****************************************************************************/

static inline FAR struct tls_info_s *up_tls_info(void)
{
  DEBUGASSERT(!up_interrupt_context());
  return TLS_INFO((uintptr_t)up_getsp());
}

#endif /* CONFIG_TLS */
#endif /* __ARCH_ARM_INCLUDE_TLS_H */