It's a much better name if you think of it as task-fork or thread-fork in the sense that it either modifies this task or creates a new one. This call will be used to provide user-space threads as well as fork(2).
68 lines
2 KiB
ArmAsm
68 lines
2 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012.
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This file is part of LibMaxsi.
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LibMaxsi is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by the Free
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Software Foundation, either version 3 of the License, or (at your option)
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any later version.
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LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details.
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You should have received a copy of the GNU Lesser General Public License
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along with LibMaxsi. 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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.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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# 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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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 $after_fork # rip, child will start execution from here.
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# Call tfork with a nice pointer to our structure. Note that %rdi contains
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# the flag parameter that this function accepted.
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movq %rsp, %rsi
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call tfork
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after_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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