sysdeps/unix/sysv/linux/sh/makecontext.S

   1 /* Create new context.
   2    Copyright (C) 2005-2016 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20 #include <abort-instr.h>
  21
  22 #include "ucontext_i.h"
  23
  24 /* void __makecontext (struct ucontext *ucp, void (*func)(), int argc, ...);
  25   __makecontext sets up a stack and registers for context to run a given
  26   function.  The registers are set up like this:
  27     r4-r7: parameters 1 to 4
  28     r8   : uc_link from ucontext structure
  29     pc   : (*func) pointer
  30     pr   : address of exitcode
  31     r15  : stack pointer for func.  */
  32
  33         .text
  34         .align  5
  35 ENTRY(__makecontext)
  36         mov     #4, r3
  37         mov.l   @(oSS_SP,r4), r1        /* r1 <- ucb->stack_base */
  38         mov.l   @(oSS_SIZE,r4), r2      /* r2 <- ucb->stack_size */
  39         add     r1, r2                  /* r2 <- stack_top */
  40         cmp/gt  r3, r6                  /* argc > 4? */
  41         bf/s    1f
  42          shlr2  r2                      /* r2 <- stack_top / 4 */
  43         sub     r6, r2
  44         add     r3, r2
  45 1:
  46         shll2   r2              /* r2 <- stack_top - ((argc > 4) ? 4 * (argc - 4) : 0 */
  47         mov     #oR15, r0
  48         mov.l   @(oLINK,r4), r1
  49         mov.l   r2, @(r0,r4)    /* ucp->r15 <- r2 */
  50         mov.l   r1, @(oR8,r4)   /* ucp->r8 <- ucp->uc_link */
  51         mov     #oPC, r0
  52         mov.l   r5, @(r0,r4)    /* ucp->PC <- func */
  53
  54         cmp/pl  r6              /* argc > 0? */
  55         bf/s    .L1
  56          dt     r6
  57         mov.l   r7, @(oR4,r4)   /* ucp->r4 <- argv[0] */
  58         cmp/pl  r6              /* argc > 1? */
  59         bf/s    .L1
  60          dt     r6
  61         mov.l   @(0,r15), r1
  62         mov.l   r1, @(oR5,r4)   /* ucp->r5 <- argv[1] */
  63         cmp/pl  r6              /* argc > 2? */
  64         bf/s    .L1
  65          dt     r6
  66         mov.l   @(4,r15), r1
  67         mov.l   r1, @(oR6,r4)   /* ucp->r6 <- argv[2] */
  68         cmp/pl  r6              /* argc > 3? */
  69         bf/s    .L1
  70          dt     r6
  71         mov.l   @(8,r15), r1
  72         mov.l   r1, @(oR7,r4)   /* ucp->r7 <- argv[3] */
  73         mov     #12,r0
  74 .L0:                            /* Save remaining argv[] on the stack.  */
  75         cmp/pl  r6
  76         bf/s    .L1
  77          dt     r6
  78         mov.l   @(r0,r15), r1
  79         mov.l   r1, @r2
  80         add     #4, r0
  81         bra     .L0
  82          add    #4, r2
  83 .L1:
  84 #ifdef PIC
  85         mova    .Lexitcode, r0
  86 #else
  87         mov.l   .L2, r0
  88 #endif
  89         add     #oPR, r4
  90         rts
  91          mov.l  r0, @r4         /* ucp->pr <- exitcode */
  92 #ifndef PIC
  93         .align  2
  94 .L2:
  95         .long   .Lexitcode
  96 #endif
  97         cfi_endproc
  98
  99         .align  5
 100         cfi_startproc
 101 .Lexitcode:
 102 #ifdef PIC
 103         mov.l   r12, @-r15
 104         cfi_adjust_cfa_offset (4)
 105         cfi_rel_offset (r12, 0)
 106         mova    .Lgot, r0
 107         mov.l   .Lgot, r12
 108         add     r0, r12
 109 #endif
 110         tst     r8, r8          /* ucb->uc_link == NULL? */
 111         bt/s    2f
 112          mov    r8, r4          /* r4 <- ucb->uc_link */
 113         mov.l   .Lsetcontext, r1
 114         sts.l   pr, @-r15
 115         cfi_adjust_cfa_offset (4)
 116         cfi_rel_offset (pr, 0)
 117 #ifdef PIC
 118         bsrf    r1
 119 .LPCS0:
 120          nop
 121 #else
 122         jsr     @r1
 123          nop
 124 #endif
 125         /* Restore to keep CFI/CFA balanced.  */
 126         lds.l   @r15+, pr
 127         cfi_adjust_cfa_offset (-4)
 128         cfi_restore (pr)
 129         /* If this returns (which can happen if the syscall fails) we'll exit
 130            the program with the return error value (-1).  */
 131         mov     r0, r4
 132
 133 2:
 134         mov.l   .Lexit, r1
 135 #ifdef PIC
 136         add     r12, r1
 137 #endif
 138         jsr     @r1
 139          nop
 140         /* The 'exit' call should never return.  In case it does cause the
 141            process to terminate.  */
 142         ABORT_INSTRUCTION_ASM
 143
 144         .align  2
 145 #ifdef PIC
 146 .Lgot:
 147         .long   _GLOBAL_OFFSET_TABLE_
 148 .Lsetcontext:
 149         .long   __setcontext@PLT-(.LPCS0+2-(.))
 150 .Lexit:
 151         .long   HIDDEN_JUMPTARGET(exit)@GOTOFF
 152 #else
 153 .Lsetcontext:
 154         .long   __setcontext
 155 .Lexit:
 156         .long   HIDDEN_JUMPTARGET(exit)
 157 #endif
 158 PSEUDO_END(__makecontext)
 159
 160 weak_alias (__makecontext, makecontext)