16k: bionic: Fix tests for x86_64 16kb page size simulation

On x86_64 based 16kb page size targets, the page size in userspace
(provided by getpagesize()) would be simulated to 16kb but the
underlying filesystem block size would remain unchanged, i.e., 4kb.

Bug: 315509500
Test: lunch aosp_cf_x86_64_phone_pgagnostic-trunk_staging-userdebug
      atest sys_vfs
      atest sys_statvfs
Change-Id: I64ba8a55fa91a98e7d2de890059991693abdc002

Author: Vilas Bhat

tests/sys_statvfs_test.cpp

@@ -25,7 +25,15 @@
 #include <string>
 
 template <typename StatVfsT> void Check(StatVfsT& sb) {
+#if defined(__x86_64__)
+  // On x86_64 based 16kb page size targets, the page size in userspace is simulated to 16kb but
+  // the underlying filesystem block size would remain unchanged, i.e., 4kb.
+  // For more info:
+  // https://source.android.com/docs/core/architecture/16kb-page-size/getting-started-cf-x86-64-pgagnostic
+  EXPECT_EQ(4096, static_cast<int>(sb.f_bsize));
+#else
   EXPECT_EQ(getpagesize(), static_cast<int>(sb.f_bsize));
+#endif
   EXPECT_EQ(0U, sb.f_bfree);
   EXPECT_EQ(0U, sb.f_ffree);
   EXPECT_EQ(255U, sb.f_namemax);

tests/sys_vfs_test.cpp

@@ -27,7 +27,15 @@
 #include "utils.h"
 
 template <typename StatFsT> void Check(StatFsT& sb) {
+#if defined(__x86_64__)
+  // On x86_64 based 16kb page size targets, the page size in userspace is simulated to 16kb but
+  // the underlying filesystem block size would remain unchanged, i.e., 4kb.
+  // For more info:
+  // https://source.android.com/docs/core/architecture/16kb-page-size/getting-started-cf-x86-64-pgagnostic
+  EXPECT_EQ(4096, static_cast<int>(sb.f_bsize));
+#else
   EXPECT_EQ(getpagesize(), static_cast<int>(sb.f_bsize));
+#endif
   EXPECT_EQ(0U, sb.f_bfree);
   EXPECT_EQ(0U, sb.f_ffree);
   EXPECT_EQ(255, static_cast<int>(sb.f_namelen));