57 lines
1.8 KiB
ArmAsm
57 lines
1.8 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix 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 General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x64/interlock.s
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Functions that perform non-atomic operations in an atomic manner.
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*******************************************************************************/
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.section .text
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# Atomicly runs a function on a value and returns the unmodified value.
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# ilret_t
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# asm_interlocked_modify(unsigned long* val,
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# unsigned long (*func)(unsigned long, unsigned long),
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# unsigned long user);
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.global asm_interlocked_modify
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.type asm_interlocked_modify, @function
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asm_interlocked_modify:
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pushq %rbp
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movq %rsp, %rbp
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asm_interlocked_modify_retry:
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# Save our parameters in case we need to retry.
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pushq %rdi
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pushq %rsi
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pushq %rdx
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# Read the current value and calculate the replacement.
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movq (%rdi), %rdi
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movq %rdx, %rsi
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callq *%rsi
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movq %rax, %rdx
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popq %rax
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popq %rdi
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popq %rsi
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# Atomicly assign the replacement if the value is unchanged.
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cmpxchgq %rdx, (%rdi)
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# Retry if the value was modified by someone else.
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jnz asm_interlocked_modify_retry
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# Return the old value in %rax, new one in %rdx.
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leaveq
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retq
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