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/* makecontext() for FreeBSD/amd64.
Copyright (C) 2006 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Petr Salinger, 2006.
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>
/*
void makecontext(ucontext_t *ucp, void *func(), int argc, ...);
input parameters:
rdi ucp
rsi func
edx argc
rcx arg1 -> ucp.rdi
r8 arg2 -> ucp.rsi
r9 arg3 -> ucp.rdx
8(%rsp) arg4 -> ucp.rcx
16(%rsp) arg5 -> ucp.r8
24(%rsp) arg6 -> ucp.r9
i*8+24(%rsp) arg(6+i)-> future stack
*/
ENTRY(__makecontext)
/* Compute the address of the stack.
The information comes from us_stack element. */
movq oSS_SP(%rdi), %rax
addq oSS_SIZE(%rdi), %rax
/* Put start addr into ucp */
movq %rsi, oRIP(%rdi)
/* properly align future stack */
andq $-16, %rax
subq $8, %rax
/* Put the next context into preserved ucp.rbx
(from the uc_link element). */
movq oLINK(%rdi), %rsi
movq %rsi, oRBX(%rdi)
/* save future registers arguments */
orl %edx, %edx
jz L(param_done)
decl %edx
movq %rcx, oRDI(%rdi)
jz L(param_done)
decl %edx
movq %r8, oRSI(%rdi)
jz L(param_done)
decl %edx
movq %r9, oRDX(%rdi)
jz L(param_done)
movq 8(%rsp), %rsi
decl %edx
movq %rsi, oRCX(%rdi)
jz L(param_done)
movq 16(%rsp), %rcx
decl %edx
movq %rcx, oR8(%rdi)
jz L(param_done)
movq 24(%rsp), %rsi
decl %edx
movq %rsi, oR9(%rdi)
jz L(param_done)
/* we have to copy some arguments also on the future stack */
movl %edx, %ecx
negq %rdx
leaq -16(%rax,%rdx,8), %rax /* we a litle bit waste stack space */
orq $8, %rax
1: movq 24(%rsp,%rcx,8), %rsi
movq %rsi,(%rax,%rcx,8)
loop 1b
L(param_done):
/* Store the future stack pointer and chain helper code. */
leaq L(exitcode)(%rip), %rdx
movq %rax, oRSP(%rdi)
movq %rdx, (%rax)
/* '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. */
L(exitcode):
/* we don't bother with extra arguments left on the stack
- more than 6 arguments is rare
- setcontext changes stacks immediately
- exit will call _exit in near future
*/
movq %rbx, %rdi /* argument for either syscall */
testq %rbx, %rbx /* If it is zero exit. */
jz 2f
call JUMPTARGET(__setcontext)
/* If this returns (which can happen if the syscall fails) we'll
exit the program with the return error value (-1). */
movq %rax, %rdi
2: call HIDDEN_JUMPTARGET(exit)
/* The 'exit' call should never return. In case it does cause
the process to terminate. */
hlt
END(__makecontext)
weak_alias(__makecontext, makecontext)
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