PERF_REG_MIPS_R28
case PERF_REG_MIPS_R28 ... PERF_REG_MIPS_R31:
v = regs->regs[idx - PERF_REG_MIPS_R28 + 28];
return regnum - UNW_MIPS_R28 + PERF_REG_MIPS_R28;
case PERF_REG_MIPS_R28: