ref: 4088f72903121c5b39cd5ce9445b2fdb2783c4c1
dir: /sys/src/libc/arm64/cycles.s/
#define SYSREG(op0,op1,Cn,Cm,op2) SPR(((op0)<<19|(op1)<<16|(Cn)<<12|(Cm)<<8|(op2)<<5)) #define PMCCNTR_EL0 SYSREG(3,3,9,13,0) TEXT cycles(SB), 1, $-4 MRS PMCCNTR_EL0, R1 MOV R1, (R0) RETURN