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glibc/sysdeps/unix/sysv/linux/i386/makecontext.S
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/* Create new context. | |
Copyright (C) 2001, 2002, 2005 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 | |
/* Put the next context on the new stack (from the uc_link | |
element). */ | |
movl oLINK(%eax), %ecx | |
movl %ecx, -4(%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. */ | |
negl %ecx | |
leal -8(%edx,%ecx,4), %edx | |
negl %ecx | |
/* Store the future stack pointer. */ | |
movl %edx, oESP(%eax) | |
/* 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 | |
popl %eax /* This is the next context. */ | |
testl %eax, %eax | |
je 2f /* If it is zero exit. */ | |
pushl %eax | |
call JUMPTARGET(__setcontext) | |
/* If this returns (which can happen if the syscall fails) we'll | |
exit the program with the return error value (-1). */ | |
2: pushl %eax | |
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) |