6507 i386 makecontext(3c) needs to 16-byte align the stack

          --- old/usr/src/lib/common/i386/crti.s
          +++ new/usr/src/lib/common/i386/crti.s

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License, Version 1.0 only
   6    6   * (the "License").  You may not use this file except in compliance
   7    7   * with the License.
   8    8   *
   9    9   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10   10   * or http://www.opensolaris.org/os/licensing.
  11   11   * See the License for the specific language governing permissions
  12   12   * and limitations under the License.
  13   13   *
  14   14   * When distributing Covered Code, include this CDDL HEADER in each
  15   15   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16   16   * If applicable, add the following below this CDDL HEADER, with the
  17   17   * fields enclosed by brackets "[]" replaced with your own identifying
  18   18   * information: Portions Copyright [yyyy] [name of copyright owner]
  19   19   *
  20   20   * CDDL HEADER END
  21   21   */
  22   22  /*
  23   23   * Copyright (c) 2001 by Sun Microsystems, Inc.
  24   24   * All rights reserved.
  25   25   */
  26   26  /*
  27   27   * Copyright (c) 2013, Joyent, Inc.  All rights reserved.
  28   28   */
  29   29  
  30   30  /*
  31   31   * These crt*.o modules are provided as the bare minimum required
  32   32   * from a crt*.o for inclusion in building low level system

  33   33   * libraries.  The are only be to included in libraries which
  34   34   * contain *no* C++ code and want to avoid the startup code
  35   35   * that the C++ runtime has introduced into the crt*.o modules.
  36   36   *
  37   37   * For further details - see bug#4433015
  38   38   */
  39   39  
  40   40          .file   "crti.s"
  41   41  
  42   42  /*
  43      - * Note that when _init and _fini are called we have 16-byte alignment per the
  44      - * ABI. We need to make sure that our asm leaves it such that subsequent calls
  45      - * will be aligned. gcc expects stack alignment before the call instruction is
  46      - * executed. Specifically if we call function foo(), the stack pointer will be
  47      - * 0xc aligned after executing the call instruction and before executing foo's
  48      - * prologue. Note that because 16-byte alignment also ensures 4-byte alignment
  49      - * we will not be breaking compatibility with older applications.
       43 + * Note that when _init and _fini are called the stack needs to be 16-byte
       44 + * aligned with a 4-byte bias.  See comment in lib/libc/i386/gen/makectxt.c.
       45 + *
       46 + * Note: If you change it, you need to change it in the following files as
       47 + * well:
       48 + *
       49 + *  - lib/libc/i386/threads/machdep.c
       50 + *  - lib/libc/i386/gen/makectxt.c
       51 + *  - lib/common/i386/crt1.s
  50   52   */
  51   53  
  52   54  /*
  53   55   * _init function prologue
  54   56   */
  55   57          .section        .init,"ax"
  56   58          .globl  _init
  57   59          .type   _init,@function
  58   60          .align  16
  59   61  _init:

  60   62          pushl   %ebp
  61   63          movl    %esp, %ebp
  62   64          andl    $-16,%esp
  63   65          subl    $12,%esp
  64   66          pushl   %ebx
  65   67          call    .L1
  66   68  .L1:    popl    %ebx
  67   69          addl    $_GLOBAL_OFFSET_TABLE_+[.-.L1], %ebx
  68   70  
  69   71  /*
  70   72   * _fini function prologue
  71   73   */
  72   74          .section        .fini,"ax"
  73   75          .globl  _fini
  74   76          .type   _fini,@function
  75   77          .align  16
  76   78  _fini:
  77   79          pushl   %ebp
  78   80          movl    %esp, %ebp
  79   81          andl    $-16,%esp
  80   82          subl    $12,%esp
  81   83          pushl   %ebx
  82   84          call    .L2
  83   85  .L2:    popl    %ebx
  84   86          addl    $_GLOBAL_OFFSET_TABLE_+[.-.L2], %ebx

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