Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
55 lines
1009 B
ArmAsm
55 lines
1009 B
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 __percpu (%rsi), %rax
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jne .Lnot_same
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cmpq __percpu 8(%rsi), %rdx
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jne .Lnot_same
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/* *ptr = new */
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movq %rbx, __percpu (%rsi)
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movq %rcx, __percpu 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 __percpu (%rsi), %rax
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movq __percpu 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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