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_

src/cpuinfo_ppc.c

@@ -168,6 +168,7 @@ PPCPlatformStrings GetPPCPlatformStrings(void) {
   PPCPlatformStrings strings = kEmptyPPCPlatformStrings;
 
   FillProcCpuInfoData(&strings);
+  strings.type = CpuFeatures_GetPlatformType();
   return strings;
 }
 

src/hwcaps.c

@@ -12,9 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "internal/hwcaps.h"
+#include <stdlib.h>
+#include <string.h>
+
 #include "cpu_features_macros.h"
 #include "internal/filesystem.h"
+#include "internal/hwcaps.h"
+#include "internal/string_view.h"
 
 #if defined(NDEBUG)
 #define D(...)
@@ -71,6 +75,9 @@ static unsigned long GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
 #include <dlfcn.h>
 #define AT_HWCAP 16
 #define AT_HWCAP2 26
+#define AT_PLATFORM 15
+#define AT_BASE_PLATFORM 24
+
 typedef unsigned long getauxval_func_t(unsigned long);
 
 static uint32_t GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
@@ -152,6 +159,21 @@ HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
   return capabilities;
 }
 
+PlatformType kEmptyPlatformType;
+
+PlatformType CpuFeatures_GetPlatformType(void) {
+  PlatformType type = kEmptyPlatformType;
+  char *platform = (char *)GetHardwareCapabilitiesFor(AT_PLATFORM);
+  char *base_platform = (char *)GetHardwareCapabilitiesFor(AT_BASE_PLATFORM);
+
+  if (platform != NULL)
+    CpuFeatures_StringView_CopyString(str(platform), type.platform,
+                                      sizeof(type.platform));
+  if (base_platform != NULL)
+    CpuFeatures_StringView_CopyString(str(base_platform), type.base_platform,
+                                      sizeof(type.base_platform));
+  return type;
+}
 #else  // (defined(HWCAPS_SUPPORTED)
 
 ////////////////////////////////////////////////////////////////////////////////

src/utils/list_cpu_features.c

@@ -198,6 +198,8 @@ static void PrintFeatures(const Printer printer) {
   PrintS(printer, "model", strings.model);
   PrintS(printer, "machine", strings.machine);
   PrintS(printer, "cpu", strings.cpu);
+  PrintS(printer, "instruction set", strings.type.platform);
+  PrintS(printer, "microarchitecture", strings.type.base_platform);
   PrintFlags(printer, &info.features);
 #endif
 }

test/cpuinfo_ppc_test.cc

@@ -57,11 +57,14 @@ timebase        : 512000000
 platform        : pSeries
 model           : IBM,8406-70Y
 machine         : CHRP IBM,8406-70Y)");
+  SetPlatformTypes("power7", "power8");
   const auto strings = GetPPCPlatformStrings();
   ASSERT_STREQ(strings.platform, "pSeries");
   ASSERT_STREQ(strings.model, "IBM,8406-70Y");
   ASSERT_STREQ(strings.machine, "CHRP IBM,8406-70Y");
   ASSERT_STREQ(strings.cpu, "POWER7 (architected), altivec supported");
+  ASSERT_STREQ(strings.type.platform, "power7");
+  ASSERT_STREQ(strings.type.base_platform, "power8");
 }
 
 TEST(CpustringsPPCTest, Firestone) {

test/hwcaps_for_testing.cc

@@ -12,12 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <string.h>
+
 #include "hwcaps_for_testing.h"
+#include "internal/string_view.h"
 
 namespace cpu_features {
 
 namespace {
 static auto* const g_hardware_capabilities = new HardwareCapabilities();
+static auto* const g_platform_types = new PlatformType();
 }  // namespace
 
 void SetHardwareCapabilities(uint32_t hwcaps, uint32_t hwcaps2) {
@@ -29,4 +33,13 @@ HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
   return *g_hardware_capabilities;
 }
 
+void SetPlatformTypes(const char* platform, const char* base_platform) {
+  CpuFeatures_StringView_CopyString(str(platform), g_platform_types->platform,
+                                    sizeof(g_platform_types->platform));
+  CpuFeatures_StringView_CopyString(str(base_platform),
+                                    g_platform_types->base_platform,
+                                    sizeof(g_platform_types->base_platform));
+}
+
+PlatformType CpuFeatures_GetPlatformType(void) { return *g_platform_types; }
 }  // namespace cpu_features

test/hwcaps_for_testing.h

@@ -20,6 +20,7 @@
 namespace cpu_features {
 
 void SetHardwareCapabilities(uint32_t hwcaps, uint32_t hwcaps2);
+void SetPlatformTypes(const char *platform, const char *base_platform);
 
 }  // namespace cpu_features