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sortix--sortix/libc/x86/fork.S
Jonas 'Sortie' Termansen af23f7ad5e Add rdmsr(2) and wrmsr(2).
2014-05-29 17:14:30 +02:00

70 lines
2.3 KiB
ArmAsm

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012.
This file is part of the Sortix C Library.
The Sortix 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 3 of the License, or (at your
option) any later version.
The Sortix 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 Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
x86/fork.S
Assembly functions related to forking x86 processes.
*******************************************************************************/
#define MSRID_FSBASE 0xC0000100
#define MSRID_GSBASE 0xC0000101
.section .text
.globl __call_tfork_with_regs
.type __call_tfork_with_regs, @function
__call_tfork_with_regs:
pushl %ebp
movl %esp, %ebp
# The actual system call expects a struct tforkregs_x86 containing the state
# of each register in the child. Since we create an identical copy, we
# simply set each member of the structure to our own state. Note that since
# the stack goes downwards, we create it in the reverse order.
pushl $MSRID_GSBASE
call rdmsr
movl %eax, (%esp)
pushl $MSRID_FSBASE
call rdmsr
movl %eax, (%esp)
pushfl
pushl %ebp
pushl %esp
pushl %esi
pushl %edi
pushl %edx
pushl %ecx
pushl %ebx
pushl $0 # eax, result of sfork (0 for the child).
pushl $.Lafter_fork # rip, child will start execution from here.
# Call tfork with a nice pointer to our structure. Note that %edi contains
# the flag parameter that this function accepted.
movl 8(%ebp), %edx # flags parameter, edx need not be preserved.
pushl %esp
pushl %edx
call tfork
.Lafter_fork:
# The value in %eax: determines whether we are child or parent. There is no
# need to clean up the stack from the above pushes, leavel sets %esp to %ebp
# which does that for us.
leavel
retl
.size __call_tfork_with_regs, . - __call_tfork_with_regs