2022-04-02 18:08:56 +05:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef __ASM_VDSO_PROCESSOR_H
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#define __ASM_VDSO_PROCESSOR_H
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#ifndef __ASSEMBLY__
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2022-09-13 23:14:27 +05:00
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#include <linux/jump_label.h>
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2022-04-02 18:08:56 +05:00
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#include <asm/barrier.h>
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2022-09-13 23:14:27 +05:00
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#include <asm/hwcap.h>
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2022-04-02 18:08:56 +05:00
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static inline void cpu_relax(void)
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{
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2022-09-13 23:14:27 +05:00
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if (!static_branch_likely(&riscv_isa_ext_keys[RISCV_ISA_EXT_KEY_ZIHINTPAUSE])) {
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2022-04-02 18:08:56 +05:00
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#ifdef __riscv_muldiv
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2022-09-13 23:14:27 +05:00
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int dummy;
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/* In lieu of a halt instruction, induce a long-latency stall. */
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__asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy));
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2022-04-02 18:08:56 +05:00
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#endif
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2022-09-13 23:14:27 +05:00
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} else {
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/*
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* Reduce instruction retirement.
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* This assumes the PC changes.
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*/
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2022-12-14 10:45:59 +05:00
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#ifdef CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE
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2022-09-13 23:14:27 +05:00
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__asm__ __volatile__ ("pause");
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#else
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/* Encoding of the pause instruction */
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__asm__ __volatile__ (".4byte 0x100000F");
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#endif
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}
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2022-04-02 18:08:56 +05:00
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barrier();
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}
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_VDSO_PROCESSOR_H */
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