--- old/usr/src/lib/libc/i386/sys/getcontext.S
          +++ new/usr/src/lib/libc/i386/sys/getcontext.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 (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *
  19   19   * CDDL HEADER END
  20   20   */
  21   21  
  22   22  /*
  23   23   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24   24   * Use is subject to license terms.
  25   25   */
  26   26  
  27   27  /*
  28   28   * Copyright 2023 Oxide Computer Company
  29   29   */
  30   30  
  31   31          .file   "getcontext.s"
  32   32  
  33   33  #include <sys/asm_linkage.h>
  34   34  
  35   35          ANSI_PRAGMA_WEAK(getcontext,function)
  36   36          ANSI_PRAGMA_WEAK(swapcontext,function)
  37   37  
  38   38  #include "SYS.h"
  39   39  #include <assym.h>
  40   40  
  41   41  /*
  42   42   * getcontext() and swapcontext() are written in assembler since it has to
  43   43   * capture the correct machine state of the caller, including
  44   44   * the registers: %edi, %esi and %ebx.
  45   45   *
  46   46   * As swapcontext() is actually equivalent to getcontext() + setcontext(),
  47   47   * swapcontext() shares the most code with getcontext().
  48   48   */
  49   49  
  50   50  
  51   51  #define GETCONTEXT_IMPL(func)                                           \
  52   52          movl    4(%esp), %eax;          /* %eax <-- first arg: ucp */   \
  53   53          pushl   %eax;                   /* push ucp for system call */  \
  54   54          call    func;                   /* call getcontext: syscall */  \
  55   55          addl    $4, %esp;               /* pop arg */                   \
  56   56          andl    %eax, %eax;             /* if (err_ret_from_syscall) */ \
  57   57          je      1f;                                                     \
  58   58          ret;                            /*      then return */          \
  59   59  1:                                                                      \
  60   60          movl    4(%esp), %eax;          /* recompute first arg */       \
  61   61          /*                                                              \
  62   62           * fix up %esp and %eip                                         \
  63   63           */                                                             \
  64   64          leal    UC_MCONTEXT_GREGS (%eax), %edx;                         \
  65   65                                  /* %edx <-- &ucp->uc_mcontext.gregs */  \
  66   66          movl    0(%esp), %eax;  /* read return PC from stack */         \
  67   67          movl    %eax, EIP_OFF (%edx);                                   \
  68   68                                  /* store ret PC in EIP of env var */    \
  69   69          leal    4(%esp), %eax;  /* get caller's sp at time of call */   \
  70   70          movl    %eax, UESP_OFF (%edx);                                  \
  71   71                                  /* store the sp into UESP of env var */ \
  72   72          xorl    %eax, %eax;     /* return 0 */                          \
  73   73          movl    %eax, EAX_OFF (%edx);                                   \
  74   74                                  /* getcontext returns 0 after a setcontext */
  75   75  
  76   76  /*
  77   77   * int getcontext(ucontext_t *ucp)
  78   78   */
  79   79          ENTRY(getcontext)
  80   80          GETCONTEXT_IMPL(__getcontext)
  81   81          ret
  82   82          SET_SIZE(getcontext)
  83   83  
  84   84  
  85   85  /*
  86   86   * int swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
  87   87   */
  88   88          ENTRY(swapcontext)
  89   89          GETCONTEXT_IMPL(__getcontext)
  90   90          /* call setcontext */
  91   91          movl    8(%esp), %eax           /* %eax <-- second arg: ucp */
  92   92          pushl   %eax                    /* push ucp for setcontext */
  93   93          call    setcontext
  94   94          addl    $4, %esp                /* pop arg: just in case */
  95   95          ret
  96   96          SET_SIZE(swapcontext)
  97   97  
  98   98  /*
  99   99   * int getcontext_extd(ucontext_t *ucp, uint32_t flags)
 100  100   */
 101  101          ENTRY(getcontext_extd)
 102  102          movl    8(%esp), %eax
 103  103          cmpl    $0, %eax                /* if (flags != 0) */
 104  104          jne     2f
 105  105          GETCONTEXT_IMPL(__getcontext_extd)
 106  106          ret
 107  107  2:
 108  108          movl    $EINVAL, %eax           /* errno = EINVAL; */
 109  109          jmp     __cerror                /* return (-1) */
 110  110          SET_SIZE(getcontext_extd)
 111  111  
 112  112  
 113  113  /*
 114  114   * int swapcontext_extd(ucontext_t *oucp, const ucontext_t *ucp)
 115  115   */
 116  116          ENTRY(swapcontext_extd)
 117  117          movl    8(%esp), %eax
 118  118          cmpl    $0, %eax                /* if (flags != 0) */
 119  119          jne     2f
 120  120          GETCONTEXT_IMPL(__getcontext_extd)
 121  121          /* call setcontext */
 122  122          movl    12(%esp), %eax          /* %eax <-- second arg: ucp */
 123  123          pushl   %eax                    /* push ucp for setcontext */
 124  124          call    setcontext
 125  125          addl    $4, %esp                /* pop arg: just in case */
 126  126          ret
 127  127  2:
 128  128          movl    $EINVAL, %eax           /* errno = EINVAL; */
 129  129          jmp     __cerror                /* return (-1) */
 130  130          SET_SIZE(swapcontext_extd)

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