71 lines
2.3 KiB
ArmAsm
71 lines
2.3 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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x86/fork.S
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Assembly functions related to forking x86 processes.
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*******************************************************************************/
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#define MSRID_FSBASE 0xC0000100
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#define MSRID_GSBASE 0xC0000101
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.section .text
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.globl __call_tfork_with_regs
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.type __call_tfork_with_regs, @function
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__call_tfork_with_regs:
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pushl %ebp
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movl %esp, %ebp
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# The actual system call expects a struct tforkregs_x86 containing the state
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# of each register in the child. Since we create an identical copy, we
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# simply set each member of the structure to our own state. Note that since
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# the stack goes downwards, we create it in the reverse order.
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pushl $MSRID_GSBASE
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call rdmsr
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movl %eax, (%esp)
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pushl $MSRID_FSBASE
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call rdmsr
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movl %eax, (%esp)
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pushfl
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pushl %ebp
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pushl %esp
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pushl %esi
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pushl %edi
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pushl %edx
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pushl %ecx
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pushl %ebx
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pushl $0 # eax, result of sfork (0 for the child).
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pushl $.Lafter_fork # rip, child will start execution from here.
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# Call tfork with a nice pointer to our structure. Note that %edi contains
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# the flag parameter that this function accepted.
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movl 8(%ebp), %edx # flags parameter, edx need not be preserved.
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pushl %esp
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pushl %edx
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call tfork
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.Lafter_fork:
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# The value in %eax: determines whether we are child or parent. There is no
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# need to clean up the stack from the above pushes, leavel sets %esp to %ebp
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# which does that for us.
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leavel
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retl
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.size __call_tfork_with_regs, . - __call_tfork_with_regs
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