54 lines
1.1 KiB
ArmAsm
54 lines
1.1 KiB
ArmAsm
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*
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*/
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#include <linux/linkage.h>
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#include <asm/percpu.h>
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.text
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/*
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* Inputs:
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* %rsi : memory location to compare
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* %rax : low 64 bits of old value
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* %rdx : high 64 bits of old value
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* %rbx : low 64 bits of new value
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* %rcx : high 64 bits of new value
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* %al : Operation successful
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*/
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ENTRY(this_cpu_cmpxchg16b_emu)
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#
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# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not
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# via the ZF. Caller will access %al to get result.
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#
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# Note that this is only useful for a cpuops operation. Meaning that we
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# do *not* have a fully atomic operation but just an operation that is
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# *atomic* on a single cpu (as provided by the this_cpu_xx class of
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# macros).
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#
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pushfq
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cli
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cmpq PER_CPU_VAR((%rsi)), %rax
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jne .Lnot_same
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cmpq PER_CPU_VAR(8(%rsi)), %rdx
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jne .Lnot_same
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movq %rbx, PER_CPU_VAR((%rsi))
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movq %rcx, PER_CPU_VAR(8(%rsi))
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popfq
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mov $1, %al
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ret
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.Lnot_same:
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popfq
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xor %al,%al
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ret
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ENDPROC(this_cpu_cmpxchg16b_emu)
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