81 lines
2.3 KiB
ArmAsm
81 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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x64/fork.S
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Assembly functions related to forking x64 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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pushq %rbp
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movq %rsp, %rbp
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# Save the flags parameter so rdmsr won't trash it and align stack.
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pushq %rdi
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sub $8, %rsp
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# The actual system call expects a struct tforkregs_x64 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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movl $MSRID_GSBASE, %edi
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call rdmsr
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pushq %rax
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movl $MSRID_FSBASE, %edi
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call rdmsr
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pushq %rax
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movq -8(%rbp), %rdi
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pushfq
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pushq %r15
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pushq %r14
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pushq %r13
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pushq %r12
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pushq %r11
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pushq %r10
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pushq %r9
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pushq %r8
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pushq %rbp
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pushq %rsp
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pushq %rsi
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pushq %rdi
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pushq %rdx
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pushq %rcx
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pushq %rbx
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pushq $0 # rax, result of sfork is 0 for the child.
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pushq $.Lafter_fork # rip, child will start execution from here.
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# Call tfork with a nice pointer to our structure.
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movq %rsp, %rsi
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call tfork
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.Lafter_fork:
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# The value in %rax determines whether we are child or parent. There is no
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# need to clean up the stack from the above pushes, leaveq sets %rsp to %rbp
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# which does that for us.
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leaveq
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retq
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.size __call_tfork_with_regs, . - __call_tfork_with_regs
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