Add low_4gb support to MapFile and MapFileAtAddress

Motivation is to use this for loading app images in low 4GB at a
non fixed address.

Added test.

Bug: 22858531
Change-Id: I0f79a4a7bfbfbdfc112e41b25c8682b1fb932ab7

1 files changed, 23 insertions, 3 deletions

diff --git a/runtime/mem_map_test.cc b/runtime/mem_map_test.cc
index 13bf5b7698..3790e53fe3 100644
--- a/runtime/mem_map_test.cc
+++ b/runtime/mem_map_test.cc
@@ -18,13 +18,13 @@
 
 #include <memory>
 
+#include "common_runtime_test.h"
 #include "base/memory_tool.h"
-
-#include "gtest/gtest.h"
+#include "base/unix_file/fd_file.h"
 
 namespace art {
 
-class MemMapTest : public testing::Test {
+class MemMapTest : public CommonRuntimeTest {
  public:
   static uint8_t* BaseBegin(MemMap* mem_map) {
     return reinterpret_cast<uint8_t*>(mem_map->base_begin_);
@@ -164,6 +164,26 @@ TEST_F(MemMapTest, MapAnonymousEmpty32bit) {
   ASSERT_TRUE(error_msg.empty());
   ASSERT_LT(reinterpret_cast<uintptr_t>(BaseBegin(map.get())), 1ULL << 32);
 }
+TEST_F(MemMapTest, MapFile32Bit) {
+  CommonInit();
+  std::string error_msg;
+  ScratchFile scratch_file;
+  constexpr size_t kMapSize = kPageSize;
+  std::unique_ptr<uint8_t[]> data(new uint8_t[kMapSize]());
+  ASSERT_TRUE(scratch_file.GetFile()->WriteFully(&data[0], kMapSize));
+  std::unique_ptr<MemMap> map(MemMap::MapFile(/*byte_count*/kMapSize,
+                                              PROT_READ,
+                                              MAP_PRIVATE,
+                                              scratch_file.GetFd(),
+                                              /*start*/0,
+                                              /*low_4gb*/true,
+                                              scratch_file.GetFilename().c_str(),
+                                              &error_msg));
+  ASSERT_TRUE(map != nullptr) << error_msg;
+  ASSERT_TRUE(error_msg.empty());
+  ASSERT_EQ(map->Size(), kMapSize);
+  ASSERT_LT(reinterpret_cast<uintptr_t>(BaseBegin(map.get())), 1ULL << 32);
+}
 #endif
 
 TEST_F(MemMapTest, MapAnonymousExactAddr) {