1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 #ifndef __ASM_VDSO_PROCESSOR_H 3 #define __ASM_VDSO_PROCESSOR_H 4 5 #ifndef __ASSEMBLY__ 6 7 #include <linux/jump_label.h> 8 #include <asm/barrier.h> 9 #include <asm/hwcap.h> 10 11 static inline void cpu_relax(void) 12 { 13 if (!static_branch_likely(&riscv_isa_ext_keys[RISCV_ISA_EXT_KEY_ZIHINTPAUSE])) { 14 #ifdef __riscv_muldiv 15 int dummy; 16 /* In lieu of a halt instruction, induce a long-latency stall. */ 17 __asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy)); 18 #endif 19 } else { 20 /* 21 * Reduce instruction retirement. 22 * This assumes the PC changes. 23 */ 24 #ifdef __riscv_zihintpause 25 __asm__ __volatile__ ("pause"); 26 #else 27 /* Encoding of the pause instruction */ 28 __asm__ __volatile__ (".4byte 0x100000F"); 29 #endif 30 } 31 barrier(); 32 } 33 34 #endif /* __ASSEMBLY__ */ 35 36 #endif /* __ASM_VDSO_PROCESSOR_H */ 37