Fix sign problem, implement low-mem mmap wraparound
A signed value comparison meant that on 64b systems comparisons
were false when pointers > 2GB were in use (as happens in long-running
tests). Fix this to be uint.
Implement a simple wrap-around in the MAP_32BIT emulation code.
Change-Id: I09870b4755f2dca676e42e701fbb6f6eb4bb95d0
diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index e8cea9d..297f1a8 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -30,9 +30,10 @@
size_t dest_reg, size_t src_reg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// If both register locations contains the same value, the register probably holds a reference.
- int32_t src_value = shadow_frame.GetVReg(src_reg);
+ // Uint required, so that sign extension does not make this wrong on 64b systems
+ uint32_t src_value = shadow_frame.GetVReg(src_reg);
mirror::Object* o = shadow_frame.GetVRegReference<kVerifyNone>(src_reg);
- if (src_value == reinterpret_cast<intptr_t>(o)) {
+ if (src_value == reinterpret_cast<uintptr_t>(o)) {
new_shadow_frame->SetVRegReference(dest_reg, o);
} else {
new_shadow_frame->SetVReg(dest_reg, src_value);
diff --git a/runtime/mem_map.cc b/runtime/mem_map.cc
index 5647d93..0af25e7 100644
--- a/runtime/mem_map.cc
+++ b/runtime/mem_map.cc
@@ -47,7 +47,10 @@
}
#if defined(__LP64__) && !defined(__x86_64__)
-uintptr_t MemMap::next_mem_pos_ = kPageSize * 2; // first page to check for low-mem extent
+// Where to start with low memory allocation.
+static constexpr uintptr_t LOW_MEM_START = kPageSize * 2;
+
+uintptr_t MemMap::next_mem_pos_ = LOW_MEM_START; // first page to check for low-mem extent
#endif
static bool CheckMapRequest(byte* expected_ptr, void* actual_ptr, size_t byte_count,
@@ -133,7 +136,22 @@
if (low_4gb && expected == nullptr) {
flags |= MAP_FIXED;
+ bool first_run = true;
+
for (uintptr_t ptr = next_mem_pos_; ptr < 4 * GB; ptr += kPageSize) {
+ if (4U * GB - ptr < page_aligned_byte_count) {
+ // Not enough memory until 4GB.
+ if (first_run) {
+ // Try another time from the bottom;
+ next_mem_pos_ = LOW_MEM_START;
+ first_run = false;
+ continue;
+ } else {
+ // Second try failed.
+ break;
+ }
+ }
+
uintptr_t tail_ptr;
// Check pages are free.
