diff options
Diffstat (limited to 'arch/riscv/include/asm/vdso/processor.h')
-rw-r--r-- | arch/riscv/include/asm/vdso/processor.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/vdso/processor.h b/arch/riscv/include/asm/vdso/processor.h new file mode 100644 index 000000000..fa70cfe50 --- /dev/null +++ b/arch/riscv/include/asm/vdso/processor.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_VDSO_PROCESSOR_H +#define __ASM_VDSO_PROCESSOR_H + +#ifndef __ASSEMBLY__ + +#include <linux/jump_label.h> +#include <asm/barrier.h> +#include <asm/hwcap.h> + +static inline void cpu_relax(void) +{ + if (!static_branch_likely(&riscv_isa_ext_keys[RISCV_ISA_EXT_KEY_ZIHINTPAUSE])) { +#ifdef __riscv_muldiv + int dummy; + /* In lieu of a halt instruction, induce a long-latency stall. */ + __asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy)); +#endif + } else { + /* + * Reduce instruction retirement. + * This assumes the PC changes. + */ +#ifdef CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE + __asm__ __volatile__ ("pause"); +#else + /* Encoding of the pause instruction */ + __asm__ __volatile__ (".4byte 0x100000F"); +#endif + } + barrier(); +} + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_VDSO_PROCESSOR_H */ |