1  /* Copyright (C) 2002-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Default stack size.  */
      19  #define ARCH_STACK_DEFAULT_SIZE	(2 * 1024 * 1024)
      20  
      21  /* Minimum guard size.  */
      22  #define ARCH_MIN_GUARD_SIZE 0
      23  
      24  /* Required stack pointer alignment at beginning.  SSE requires 16
      25     bytes.  */
      26  #define STACK_ALIGN		16
      27  
      28  /* Minimal stack size after allocating thread descriptor and guard size.  */
      29  #define MINIMAL_REST_STACK	2048
      30  
      31  /* Alignment requirement for TCB.
      32  
      33     Some processors such as Intel Atom pay a big penalty on every
      34     access using a segment override if that segment's base is not
      35     aligned to the size of a cache line.  (See Intel 64 and IA-32
      36     Architectures Optimization Reference Manual, section 13.3.3.3,
      37     "Segment Base".)  On such machines, a cache line is 64 bytes.  */
      38  #define TCB_ALIGNMENT		64
      39  
      40  
      41  /* Location of current stack frame.  */
      42  #ifdef __x86_64__
      43  /* The frame pointer is not usable.  */
      44  # define CURRENT_STACK_FRAME \
      45    ({ register void * p__ __asm__(RSP_REG); \
      46       asm volatile("" : "=r" (p__)); \
      47       p__; })
      48  #else
      49  # define CURRENT_STACK_FRAME	__builtin_frame_address (0)
      50  #endif