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6d12c8d308
In order to replace cmpxchg_double() with the newly minted cmpxchg128() family of functions, wire it up in this_cpu_cmpxchg(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20230531132323.654945124@infradead.org
55 lines
1.0 KiB
ArmAsm
55 lines
1.0 KiB
ArmAsm
/* 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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#include <asm/processor-flags.h>
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.text
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/*
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* Emulate 'cmpxchg16b %gs:(%rsi)'
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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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*
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* Notably this is not LOCK prefixed and is not safe against NMIs
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*/
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SYM_FUNC_START(this_cpu_cmpxchg16b_emu)
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pushfq
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cli
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/* if (*ptr == old) */
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cmpq PER_CPU_VAR(0(%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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/* *ptr = new */
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movq %rbx, PER_CPU_VAR(0(%rsi))
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movq %rcx, PER_CPU_VAR(8(%rsi))
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/* set ZF in EFLAGS to indicate success */
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orl $X86_EFLAGS_ZF, (%rsp)
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popfq
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RET
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.Lnot_same:
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/* *ptr != old */
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/* old = *ptr */
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movq PER_CPU_VAR(0(%rsi)), %rax
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movq PER_CPU_VAR(8(%rsi)), %rdx
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/* clear ZF in EFLAGS to indicate failure */
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andl $(~X86_EFLAGS_ZF), (%rsp)
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popfq
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RET
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SYM_FUNC_END(this_cpu_cmpxchg16b_emu)
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