6367a2352e
sfork(2) now calls sforkr(2) with the current registers. This will prove useful in creating threads, where user-space now can fully control what state the child will start in. This is unlike the Linux clone system call that accepts a pointer to the child stack; this is more powerful and somehow simpler. Note that this will create a rather raw thread; no thread initization has been done by the standard thread API (when it is implemented), so this feature shouldn't be used by programmers unless they know what they are doing. fork(2) now calls sfork(2) directly. Also removed fork(2) and sfork(2) from the kernel as they are done using sforkr(2) now. So technically they aren't system calls right now, but that could always change.
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_sforkr_with_regs
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.type __call_sforkr_with_regs, @function
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__call_sforkr_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 sforkregs_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 sforkr 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 sforkr
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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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