| /* Create new context. |
| Copyright (C) 2001,2002,2005,2007,2008,2009 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <drepper@redhat.com>, 2001. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <sysdep.h> |
| |
| #include "ucontext_i.h" |
| |
| |
| ENTRY(__makecontext) |
| movl 4(%esp), %eax |
| |
| /* Load the address of the function we are supposed to run. */ |
| movl 8(%esp), %ecx |
| |
| /* Compute the address of the stack. The information comes from |
| to us_stack element. */ |
| movl oSS_SP(%eax), %edx |
| movl %ecx, oEIP(%eax) |
| addl oSS_SIZE(%eax), %edx |
| |
| /* Remember the number of parameters for the exit handler since |
| it has to remove them. We store the number in the EBX register |
| which the function we will call must preserve. */ |
| movl 12(%esp), %ecx |
| movl %ecx, oEBX(%eax) |
| |
| /* Make room on the new stack for the parameters. |
| Room for the arguments, return address (== L(exitcode)) and |
| oLINK pointer is needed. One of the pointer sizes is subtracted |
| after aligning the stack. */ |
| negl %ecx |
| leal -4(%edx,%ecx,4), %edx |
| negl %ecx |
| |
| /* Align the stack. */ |
| andl $0xfffffff0, %edx |
| subl $4, %edx |
| |
| /* Store the future stack pointer. */ |
| movl %edx, oESP(%eax) |
| |
| /* Put the next context on the new stack (from the uc_link |
| element). */ |
| movl oLINK(%eax), %eax |
| movl %eax, 4(%edx,%ecx,4) |
| |
| /* Copy all the parameters. */ |
| jecxz 2f |
| 1: movl 12(%esp,%ecx,4), %eax |
| movl %eax, (%edx,%ecx,4) |
| decl %ecx |
| jnz 1b |
| 2: |
| |
| /* If the function we call returns we must continue with the |
| context which is given in the uc_link element. To do this |
| set the return address for the function the user provides |
| to a little bit of helper code which does the magic (see |
| below). */ |
| #ifdef PIC |
| call 1f |
| cfi_adjust_cfa_offset (4) |
| 1: popl %ecx |
| cfi_adjust_cfa_offset (-4) |
| addl $L(exitcode)-1b, %ecx |
| movl %ecx, (%edx) |
| #else |
| movl $L(exitcode), (%edx) |
| #endif |
| /* 'makecontext' returns no value. */ |
| ret |
| |
| /* This is the helper code which gets called if a function which |
| is registered with 'makecontext' returns. In this case we |
| have to install the context listed in the uc_link element of |
| the context 'makecontext' manipulated at the time of the |
| 'makecontext' call. If the pointer is NULL the process must |
| terminate. */ |
| cfi_endproc |
| L(exitcode): |
| /* This removes the parameters passed to the function given to |
| 'makecontext' from the stack. EBX contains the number of |
| parameters (see above). */ |
| leal (%esp,%ebx,4), %esp |
| |
| #ifdef PIC |
| call 1f |
| 1: popl %ebx |
| addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx |
| #endif |
| cmpl $0, (%esp) /* Check the next context. */ |
| je 2f /* If it is zero exit. */ |
| |
| call JUMPTARGET(__setcontext) |
| /* If this returns (which can happen if the syscall fails) we'll |
| exit the program with the return error value (-1). */ |
| |
| movl %eax, (%esp) |
| 2: call HIDDEN_JUMPTARGET(exit) |
| /* The 'exit' call should never return. In case it does cause |
| the process to terminate. */ |
| hlt |
| cfi_startproc |
| END(__makecontext) |
| |
| weak_alias (__makecontext, makecontext) |
