forked from Minki/linux
b9ec40af0e
Support this_cpu_cmpxchg_double() using the cmpxchg16b and cmpxchg8b
instructions.
-tj: s/percpu_cmpxchg16b/percpu_cmpxchg16b_double/ for consistency and
other cosmetic changes.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
60 lines
1.2 KiB
ArmAsm
60 lines
1.2 KiB
ArmAsm
/*
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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/alternative-asm.h>
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#include <asm/frame.h>
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#include <asm/dwarf2.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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CFI_STARTPROC
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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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this_cpu_cmpxchg16b_emu:
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pushf
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cli
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cmpq %gs:(%rsi), %rax
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jne not_same
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cmpq %gs:8(%rsi), %rdx
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jne not_same
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movq %rbx, %gs:(%rsi)
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movq %rcx, %gs:8(%rsi)
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popf
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mov $1, %al
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ret
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not_same:
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popf
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xor %al,%al
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ret
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CFI_ENDPROC
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ENDPROC(this_cpu_cmpxchg16b_emu)
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