Reland PPC portion of "Detect cache line size on Linux for PPC hosts."

src/base/cpu.cc

Index: src/base/cpu.cc
diff --git a/src/base/cpu.cc b/src/base/cpu.cc
index 692494afcb4c935cf6939444c922e575433e7de5..777f379bae90e1e3f0155e8ec9ae5f0fe87558bc 100644
--- a/src/base/cpu.cc
+++ b/src/base/cpu.cc
@@ -312,6 +312,8 @@ CPU::CPU()
       architecture_(0),
       variant_(-1),
       part_(0),
+      icache_line_size_(UNKNOWN_CACHE_LINE_SIZE),
+      dcache_line_size_(UNKNOWN_CACHE_LINE_SIZE),
       has_fpu_(false),
       has_cmov_(false),
       has_sahf_(false),
@@ -644,9 +646,16 @@ CPU::CPU()
       if (n == 0 || entry.a_type == AT_NULL) {
         break;
       }
-      if (entry.a_type == AT_PLATFORM) {
-        auxv_cpu_type = reinterpret_cast<char*>(entry.a_un.a_val);
-        break;
+      switch (entry.a_type) {
+        case AT_PLATFORM:
+          auxv_cpu_type = reinterpret_cast<char*>(entry.a_un.a_val);
+          break;
+        case AT_ICACHEBSIZE:
+          icache_line_size_ = entry.a_un.a_val;
+          break;
+        case AT_DCACHEBSIZE:
+          dcache_line_size_ = entry.a_un.a_val;
+          break;
       }
     }
     fclose(fp);