powerpc: Add AT_PLATFORM and AT_BASE_PLATFORM

Some PowerPC machines can operate in a mode that appears different
to a process than the actual hardware. AT_PLATFORM indicates the
supported instruction set and AT_BASE_PLATFORM indicates the
actual microarchitecture of the hardware.

Signed-off-by: Rashmica Gupta <rashmica.gupta@au1.ibm.com>

include/cpuinfo_ppc.h

@@ -16,6 +16,7 @@
 #define CPU_FEATURES_INCLUDE_CPUINFO_PPC_H_
 
 #include "cpu_features_macros.h"
+#include "internal/hwcaps.h"
 
 CPU_FEATURES_START_CPP_NAMESPACE
 
@@ -77,6 +78,7 @@ typedef struct {
   char model[64];     // 0 terminated string
   char machine[64];   // 0 terminated string
   char cpu[64];       // 0 terminated string
+  PlatformType type;
 } PPCPlatformStrings;
 
 PPCPlatformStrings GetPPCPlatformStrings(void);

include/internal/hwcaps.h

@@ -119,6 +119,13 @@ typedef struct {
 
 HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void);
 
+typedef struct {
+  char platform[64];       // 0 terminated string
+  char base_platform[64];  // 0 terminated string
+} PlatformType;
+
+PlatformType CpuFeatures_GetPlatformType(void);
+
 CPU_FEATURES_END_CPP_NAMESPACE
 
 #endif  // CPU_FEATURES_INCLUDE_INTERNAL_HWCAPS_H_