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47 lines
1007 B
47 lines
1007 B
/* SPDX-License-Identifier: GPL-2.0-only */ |
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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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SYM_FUNC_START(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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SYM_FUNC_END(this_cpu_cmpxchg16b_emu)
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