cpu.c

   1 /*
   2  * cpu.c
   3  *
   4  *      CPU-specific functionality.
   5  */
   6
   7
   8 #include <marmot.h>
   9
  10
  11 struct {
  12    uint64  nStandard;
  13    uint64  nHypervisor;
  14    uint64  nExtended;
  15    struct {
  16       UReg eax;
  17       UReg ebx;
  18       UReg ecx;
  19       UReg edx;
  20    } features[];
  21 } *CPUIDInfo;
  22
  23
  24 uint32
  25 CPU_GetFeature(uint32 feature)
  26 {
  27    uint32 type, fcn, reg, bl, bh, mask, idx, features = 0;
  28
  29    type = (feature & CPUID_TYPE_MASK) >> CPUID_TYPE_SHIFT;
  30    fcn = (feature & CPUID_FCN_MASK) >> CPUID_FCN_SHIFT;
  31    reg = (feature & CPUID_REG_MASK) >> CPUID_REG_SHIFT;
  32    bl = (feature & CPUID_LBIT_MASK) >> CPUID_LBIT_SHIFT;
  33    bh = (feature & CPUID_HBIT_MASK) >> CPUID_HBIT_SHIFT;
  34
  35    mask = (~((1 << bh) - 1)) - ((1 << bl) - 1);
  36
  37    idx = 0;
  38    if (type == CPUID_FEATURES_HYPERVISOR) {
  39       if (CPUIDInfo->nHypervisor == 0) {
  40          return FALSE;
  41       }
  42
  43       idx += CPUIDInfo->nStandard;
  44    } else if (type == CPUID_FEATURES_EXTENDED) {
  45       idx += CPUIDInfo->nStandard + CPUIDInfo->nHypervisor;
  46    }
  47
  48    switch (reg) {
  49    case CPUID_REGISTER_EAX:
  50       features = CPUIDInfo->features[idx].eax;
  51       break;
  52    case CPUID_REGISTER_EBX:
  53       features = CPUIDInfo->features[idx].ebx;
  54       break;
  55    case CPUID_REGISTER_ECX:
  56       features = CPUIDInfo->features[idx].ecx;
  57       break;
  58    case CPUID_REGISTER_EDX:
  59       features = CPUIDInfo->features[idx].edx;
  60       break;
  61    }
  62
  63    return (features & mask) >> bl;
  64 }