Add implicit null pointer and stack overflow checks for Mips.

(cherry picked from commit 22bb5a2ebc1e2724179faf4660b2735dcb185f21)

Bug: 21555893
Change-Id: I2a995be128a5603d08753c14956dd8c8240ac63c

10 files changed, 242 insertions, 42 deletions

diff --git a/compiler/dex/quick/mips/call_mips.cc b/compiler/dex/quick/mips/call_mips.cc
index da12d8e..853980d 100644
--- a/compiler/dex/quick/mips/call_mips.cc
+++ b/compiler/dex/quick/mips/call_mips.cc
@@ -24,6 +24,7 @@
 #include "dex/quick/dex_file_to_method_inliner_map.h"
 #include "dex/quick/mir_to_lir-inl.h"
 #include "driver/compiler_driver.h"
+#include "driver/compiler_options.h"
 #include "entrypoints/quick/quick_entrypoints.h"
 #include "gc/accounting/card_table.h"
 #include "mips_lir.h"
@@ -285,12 +286,25 @@ void MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method)
   RegStorage check_reg = AllocPtrSizeTemp();
   RegStorage new_sp = AllocPtrSizeTemp();
   const RegStorage rs_sp = TargetPtrReg(kSp);
+  const size_t kStackOverflowReservedUsableBytes = GetStackOverflowReservedBytes(target);
+  const bool large_frame = static_cast<size_t>(frame_size_) > kStackOverflowReservedUsableBytes;
+  bool generate_explicit_stack_overflow_check = large_frame ||
+    !cu_->compiler_driver->GetCompilerOptions().GetImplicitStackOverflowChecks();
+
   if (!skip_overflow_check) {
-    // Load stack limit.
-    if (cu_->target64) {
-      LoadWordDisp(TargetPtrReg(kSelf), Thread::StackEndOffset<8>().Int32Value(), check_reg);
+    if (generate_explicit_stack_overflow_check) {
+      // Load stack limit.
+      if (cu_->target64) {
+        LoadWordDisp(TargetPtrReg(kSelf), Thread::StackEndOffset<8>().Int32Value(), check_reg);
+      } else {
+        Load32Disp(TargetPtrReg(kSelf), Thread::StackEndOffset<4>().Int32Value(), check_reg);
+      }
     } else {
-      Load32Disp(TargetPtrReg(kSelf), Thread::StackEndOffset<4>().Int32Value(), check_reg);
+      // Implicit stack overflow check.
+      // Generate a load from [sp, #-overflowsize].  If this is in the stack
+      // redzone we will get a segmentation fault.
+      Load32Disp(rs_sp, -kStackOverflowReservedUsableBytes, rs_rZERO);
+      MarkPossibleStackOverflowException();
     }
   }
   // Spill core callee saves.
@@ -298,7 +312,7 @@ void MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method)
   // NOTE: promotion of FP regs currently unsupported, thus no FP spill.
   DCHECK_EQ(num_fp_spills_, 0);
   const int frame_sub = frame_size_ - spill_count * ptr_size;
-  if (!skip_overflow_check) {
+  if (!skip_overflow_check && generate_explicit_stack_overflow_check) {
     class StackOverflowSlowPath : public LIRSlowPath {
      public:
       StackOverflowSlowPath(Mir2Lir* m2l, LIR* branch, size_t sp_displace)
@@ -329,6 +343,8 @@ void MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method)
     OpRegCopy(rs_sp, new_sp);  // Establish stack.
     cfi_.AdjustCFAOffset(frame_sub);
   } else {
+    // Here if skip_overflow_check or doing implicit stack overflow check.
+    // Just make room on the stack for the frame now.
     OpRegImm(kOpSub, rs_sp, frame_sub);
     cfi_.AdjustCFAOffset(frame_sub);
   }
diff --git a/compiler/dex/quick/mips/codegen_mips.h b/compiler/dex/quick/mips/codegen_mips.h
index 713264e..43fbcbd 100644
--- a/compiler/dex/quick/mips/codegen_mips.h
+++ b/compiler/dex/quick/mips/codegen_mips.h
@@ -79,6 +79,7 @@ class MipsMir2Lir FINAL : public Mir2Lir {
   OVERRIDE;
   LIR* CheckSuspendUsingLoad() OVERRIDE;
   RegStorage LoadHelper(QuickEntrypointEnum trampoline) OVERRIDE;
+  void ForceImplicitNullCheck(RegStorage reg, int opt_flags, bool is_wide);
   LIR* LoadBaseDisp(RegStorage r_base, int displacement, RegStorage r_dest, OpSize size,
                     VolatileKind is_volatile) OVERRIDE;
   LIR* LoadBaseIndexed(RegStorage r_base, RegStorage r_index, RegStorage r_dest, int scale,
diff --git a/compiler/dex/quick/mips/int_mips.cc b/compiler/dex/quick/mips/int_mips.cc
index f5ad7c7..1099303 100644
--- a/compiler/dex/quick/mips/int_mips.cc
+++ b/compiler/dex/quick/mips/int_mips.cc
@@ -691,6 +691,9 @@ void MipsMir2Lir::GenArrayGet(int opt_flags, OpSize size, RegLocation rl_array,
     reg_len = AllocTemp();
     // Get len.
     Load32Disp(rl_array.reg, len_offset, reg_len);
+    MarkPossibleNullPointerException(opt_flags);
+  } else {
+    ForceImplicitNullCheck(rl_array.reg, opt_flags, false);
   }
   // reg_ptr -> array data.
   OpRegRegImm(kOpAdd, reg_ptr, rl_array.reg, data_offset);
@@ -781,6 +784,9 @@ void MipsMir2Lir::GenArrayPut(int opt_flags, OpSize size, RegLocation rl_array,
     // NOTE: max live temps(4) here.
     // Get len.
     Load32Disp(rl_array.reg, len_offset, reg_len);
+    MarkPossibleNullPointerException(opt_flags);
+  } else {
+    ForceImplicitNullCheck(rl_array.reg, opt_flags, false);
   }
   // reg_ptr -> array data.
   OpRegImm(kOpAdd, reg_ptr, data_offset);
diff --git a/compiler/dex/quick/mips/target_mips.cc b/compiler/dex/quick/mips/target_mips.cc
index 4c0bd83..b098bc2 100644
--- a/compiler/dex/quick/mips/target_mips.cc
+++ b/compiler/dex/quick/mips/target_mips.cc
@@ -791,6 +791,7 @@ LIR* MipsMir2Lir::GenAtomic64Load(RegStorage r_base, int displacement, RegStorag
   RegStorage reg_ptr = TargetReg(kArg0);
   OpRegRegImm(kOpAdd, reg_ptr, r_base, displacement);
   RegStorage r_tgt = LoadHelper(kQuickA64Load);
+  ForceImplicitNullCheck(reg_ptr, 0, true);  // is_wide = true
   LIR *ret = OpReg(kOpBlx, r_tgt);
   RegStorage reg_ret;
   if (cu_->target64) {
@@ -813,6 +814,7 @@ LIR* MipsMir2Lir::GenAtomic64Store(RegStorage r_base, int displacement, RegStora
   LockCallTemps();  // Using fixed registers.
   RegStorage temp_ptr = AllocTemp();
   OpRegRegImm(kOpAdd, temp_ptr, r_base, displacement);
+  ForceImplicitNullCheck(temp_ptr, 0, true);  // is_wide = true
   RegStorage temp_value = AllocTempWide();
   OpRegCopyWide(temp_value, r_src);
   if (cu_->target64) {
diff --git a/compiler/dex/quick/mips/utility_mips.cc b/compiler/dex/quick/mips/utility_mips.cc
index 95c61cd..37e5804 100644
--- a/compiler/dex/quick/mips/utility_mips.cc
+++ b/compiler/dex/quick/mips/utility_mips.cc
@@ -21,7 +21,9 @@
 #include "base/logging.h"
 #include "dex/quick/mir_to_lir-inl.h"
 #include "dex/reg_storage_eq.h"
+#include "dex/mir_graph.h"
 #include "driver/compiler_driver.h"
+#include "driver/compiler_options.h"
 #include "mips_lir.h"
 
 namespace art {
@@ -830,6 +832,22 @@ LIR* MipsMir2Lir::LoadBaseDispBody(RegStorage r_base, int displacement, RegStora
   return res;
 }
 
+void MipsMir2Lir::ForceImplicitNullCheck(RegStorage reg, int opt_flags, bool is_wide) {
+  if (cu_->compiler_driver->GetCompilerOptions().GetImplicitNullChecks()) {
+    if (!(cu_->disable_opt & (1 << kNullCheckElimination)) && (opt_flags & MIR_IGNORE_NULL_CHECK)) {
+      return;
+    }
+    // Force an implicit null check by performing a memory operation (load) from the given
+    // register with offset 0.  This will cause a signal if the register contains 0 (null).
+    LIR* load = Load32Disp(reg, LOWORD_OFFSET, rs_rZERO);
+    MarkSafepointPC(load);
+    if (is_wide) {
+      load = Load32Disp(reg, HIWORD_OFFSET, rs_rZERO);
+      MarkSafepointPC(load);
+    }
+  }
+}
+
 LIR* MipsMir2Lir::LoadBaseDisp(RegStorage r_base, int displacement, RegStorage r_dest, OpSize size,
                                VolatileKind is_volatile) {
   if (UNLIKELY(is_volatile == kVolatile && (size == k64 || size == kDouble))
diff --git a/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index 74d5c0c..d21f5cb 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -975,6 +975,8 @@ class Dex2Oat FINAL {
       case kArm64:
       case kX86:
       case kX86_64:
+      case kMips:
+      case kMips64:
         implicit_null_checks = true;
         implicit_so_checks = true;
         break;
diff --git a/runtime/arch/mips/fault_handler_mips.cc b/runtime/arch/mips/fault_handler_mips.cc
index abe495b..8ea78eb 100644
--- a/runtime/arch/mips/fault_handler_mips.cc
+++ b/runtime/arch/mips/fault_handler_mips.cc
@@ -17,11 +17,17 @@
 
 #include "fault_handler.h"
 #include <sys/ucontext.h>
+#include "art_method-inl.h"
 #include "base/macros.h"
 #include "globals.h"
 #include "base/logging.h"
 #include "base/hex_dump.h"
+#include "registers_mips.h"
+#include "thread.h"
+#include "thread-inl.h"
 
+extern "C" void art_quick_throw_stack_overflow();
+extern "C" void art_quick_throw_null_pointer_exception();
 
 //
 // Mips specific fault handler functions.
@@ -33,16 +39,52 @@ void FaultManager::HandleNestedSignal(int sig ATTRIBUTE_UNUSED, siginfo_t* info
                                       void* context ATTRIBUTE_UNUSED) {
 }
 
-void FaultManager::GetMethodAndReturnPcAndSp(siginfo_t* siginfo ATTRIBUTE_UNUSED,
-                                             void* context ATTRIBUTE_UNUSED,
-                                             ArtMethod** out_method ATTRIBUTE_UNUSED,
-                                             uintptr_t* out_return_pc ATTRIBUTE_UNUSED,
-                                             uintptr_t* out_sp ATTRIBUTE_UNUSED) {
+void FaultManager::GetMethodAndReturnPcAndSp(siginfo_t* siginfo, void* context,
+                                             ArtMethod** out_method,
+                                             uintptr_t* out_return_pc, uintptr_t* out_sp) {
+  struct ucontext* uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+  *out_sp = static_cast<uintptr_t>(sc->sc_regs[29]);   // SP register
+  VLOG(signals) << "sp: " << *out_sp;
+  if (*out_sp == 0) {
+    return;
+  }
+
+  // In the case of a stack overflow, the stack is not valid and we can't
+  // get the method from the top of the stack.  However it's in r0.
+  uintptr_t* fault_addr = reinterpret_cast<uintptr_t*>(siginfo->si_addr);  // BVA addr
+  uintptr_t* overflow_addr = reinterpret_cast<uintptr_t*>(
+      reinterpret_cast<uint8_t*>(*out_sp) - GetStackOverflowReservedBytes(kMips));
+  if (overflow_addr == fault_addr) {
+    *out_method = reinterpret_cast<ArtMethod*>(sc->sc_regs[4]);  // A0 register
+  } else {
+    // The method is at the top of the stack.
+    *out_method = *reinterpret_cast<ArtMethod**>(*out_sp);
+  }
+
+  // Work out the return PC.  This will be the address of the instruction
+  // following the faulting ldr/str instruction.
+
+  VLOG(signals) << "pc: " << std::hex
+      << static_cast<void*>(reinterpret_cast<uint8_t*>(sc->sc_pc));
+
+  *out_return_pc = sc->sc_pc + 4;
 }
 
 bool NullPointerHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
-                                void* context ATTRIBUTE_UNUSED) {
-  return false;
+                                void* context) {
+  // The code that looks for the catch location needs to know the value of the
+  // PC at the point of call.  For Null checks we insert a GC map that is immediately after
+  // the load/store instruction that might cause the fault.
+
+  struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+
+  sc->sc_regs[31] = sc->sc_pc + 4;      // RA needs to point to gc map location
+  sc->sc_pc = reinterpret_cast<uintptr_t>(art_quick_throw_null_pointer_exception);
+  sc->sc_regs[25] = sc->sc_pc;          // make sure T9 points to the function
+  VLOG(signals) << "Generating null pointer exception";
+  return true;
 }
 
 bool SuspensionHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
@@ -50,8 +92,51 @@ bool SuspensionHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBU
   return false;
 }
 
-bool StackOverflowHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
-                                  void* context ATTRIBUTE_UNUSED) {
-  return false;
+// Stack overflow fault handler.
+//
+// This checks that the fault address is equal to the current stack pointer
+// minus the overflow region size (16K typically). The instruction that
+// generates this signal is:
+//
+// lw zero, -16384(sp)
+//
+// It will fault if sp is inside the protected region on the stack.
+//
+// If we determine this is a stack overflow we need to move the stack pointer
+// to the overflow region below the protected region.
+
+bool StackOverflowHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info, void* context) {
+  struct ucontext* uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+  VLOG(signals) << "stack overflow handler with sp at " << std::hex << &uc;
+  VLOG(signals) << "sigcontext: " << std::hex << sc;
+
+  uintptr_t sp = sc->sc_regs[29];  // SP register
+  VLOG(signals) << "sp: " << std::hex << sp;
+
+  uintptr_t fault_addr = reinterpret_cast<uintptr_t>(info->si_addr);  // BVA addr
+  VLOG(signals) << "fault_addr: " << std::hex << fault_addr;
+  VLOG(signals) << "checking for stack overflow, sp: " << std::hex << sp <<
+    ", fault_addr: " << fault_addr;
+
+  uintptr_t overflow_addr = sp - GetStackOverflowReservedBytes(kMips);
+
+  // Check that the fault address is the value expected for a stack overflow.
+  if (fault_addr != overflow_addr) {
+    VLOG(signals) << "Not a stack overflow";
+    return false;
+  }
+
+  VLOG(signals) << "Stack overflow found";
+
+  // Now arrange for the signal handler to return to art_quick_throw_stack_overflow_from.
+  // The value of RA must be the same as it was when we entered the code that
+  // caused this fault.  This will be inserted into a callee save frame by
+  // the function to which this handler returns (art_quick_throw_stack_overflow).
+  sc->sc_pc = reinterpret_cast<uintptr_t>(art_quick_throw_stack_overflow);
+  sc->sc_regs[25] = sc->sc_pc;          // make sure T9 points to the function
+
+  // The kernel will now return to the address in sc->arm_pc.
+  return true;
 }
 }       // namespace art
diff --git a/runtime/arch/mips64/fault_handler_mips64.cc b/runtime/arch/mips64/fault_handler_mips64.cc
index 277c2b2..4abfcf1 100644
--- a/runtime/arch/mips64/fault_handler_mips64.cc
+++ b/runtime/arch/mips64/fault_handler_mips64.cc
@@ -17,11 +17,17 @@
 
 #include "fault_handler.h"
 #include <sys/ucontext.h>
+#include "art_method-inl.h"
 #include "base/macros.h"
 #include "globals.h"
 #include "base/logging.h"
 #include "base/hex_dump.h"
+#include "registers_mips64.h"
+#include "thread.h"
+#include "thread-inl.h"
 
+extern "C" void art_quick_throw_stack_overflow();
+extern "C" void art_quick_throw_null_pointer_exception();
 
 //
 // Mips64 specific fault handler functions.
@@ -33,16 +39,52 @@ void FaultManager::HandleNestedSignal(int sig ATTRIBUTE_UNUSED, siginfo_t* info
                                       void* context ATTRIBUTE_UNUSED) {
 }
 
-void FaultManager::GetMethodAndReturnPcAndSp(siginfo_t* siginfo ATTRIBUTE_UNUSED,
-                                             void* context ATTRIBUTE_UNUSED,
-                                             ArtMethod** out_method ATTRIBUTE_UNUSED,
-                                             uintptr_t* out_return_pc ATTRIBUTE_UNUSED,
-                                             uintptr_t* out_sp ATTRIBUTE_UNUSED) {
+void FaultManager::GetMethodAndReturnPcAndSp(siginfo_t* siginfo, void* context,
+                                             ArtMethod** out_method,
+                                             uintptr_t* out_return_pc, uintptr_t* out_sp) {
+  struct ucontext* uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+  *out_sp = static_cast<uintptr_t>(sc->sc_regs[29]);   // SP register
+  VLOG(signals) << "sp: " << *out_sp;
+  if (*out_sp == 0) {
+    return;
+  }
+
+  // In the case of a stack overflow, the stack is not valid and we can't
+  // get the method from the top of the stack.  However it's in r0.
+  uintptr_t* fault_addr = reinterpret_cast<uintptr_t*>(siginfo->si_addr);  // BVA addr
+  uintptr_t* overflow_addr = reinterpret_cast<uintptr_t*>(
+      reinterpret_cast<uint8_t*>(*out_sp) - GetStackOverflowReservedBytes(kMips64));
+  if (overflow_addr == fault_addr) {
+    *out_method = reinterpret_cast<ArtMethod*>(sc->sc_regs[4]);  // A0 register
+  } else {
+    // The method is at the top of the stack.
+    *out_method = *reinterpret_cast<ArtMethod**>(*out_sp);
+  }
+
+  // Work out the return PC.  This will be the address of the instruction
+  // following the faulting ldr/str instruction.
+
+  VLOG(signals) << "pc: " << std::hex
+      << static_cast<void*>(reinterpret_cast<uint8_t*>(sc->sc_pc));
+
+  *out_return_pc = sc->sc_pc + 4;
 }
 
 bool NullPointerHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
-                                void* context ATTRIBUTE_UNUSED) {
-  return false;
+                                void* context) {
+  // The code that looks for the catch location needs to know the value of the
+  // PC at the point of call.  For Null checks we insert a GC map that is immediately after
+  // the load/store instruction that might cause the fault.
+
+  struct ucontext *uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+
+  sc->sc_regs[31] = sc->sc_pc + 4;      // RA needs to point to gc map location
+  sc->sc_pc = reinterpret_cast<uintptr_t>(art_quick_throw_null_pointer_exception);
+  sc->sc_regs[25] = sc->sc_pc;          // make sure T9 points to the function
+  VLOG(signals) << "Generating null pointer exception";
+  return true;
 }
 
 bool SuspensionHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
@@ -50,8 +92,51 @@ bool SuspensionHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBU
   return false;
 }
 
-bool StackOverflowHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info ATTRIBUTE_UNUSED,
-                                  void* context ATTRIBUTE_UNUSED) {
-  return false;
+// Stack overflow fault handler.
+//
+// This checks that the fault address is equal to the current stack pointer
+// minus the overflow region size (16K typically). The instruction that
+// generates this signal is:
+//
+// lw zero, -16384(sp)
+//
+// It will fault if sp is inside the protected region on the stack.
+//
+// If we determine this is a stack overflow we need to move the stack pointer
+// to the overflow region below the protected region.
+
+bool StackOverflowHandler::Action(int sig ATTRIBUTE_UNUSED, siginfo_t* info, void* context) {
+  struct ucontext* uc = reinterpret_cast<struct ucontext*>(context);
+  struct sigcontext *sc = reinterpret_cast<struct sigcontext*>(&uc->uc_mcontext);
+  VLOG(signals) << "stack overflow handler with sp at " << std::hex << &uc;
+  VLOG(signals) << "sigcontext: " << std::hex << sc;
+
+  uintptr_t sp = sc->sc_regs[29];  // SP register
+  VLOG(signals) << "sp: " << std::hex << sp;
+
+  uintptr_t fault_addr = reinterpret_cast<uintptr_t>(info->si_addr);  // BVA addr
+  VLOG(signals) << "fault_addr: " << std::hex << fault_addr;
+  VLOG(signals) << "checking for stack overflow, sp: " << std::hex << sp <<
+    ", fault_addr: " << fault_addr;
+
+  uintptr_t overflow_addr = sp - GetStackOverflowReservedBytes(kMips64);
+
+  // Check that the fault address is the value expected for a stack overflow.
+  if (fault_addr != overflow_addr) {
+    VLOG(signals) << "Not a stack overflow";
+    return false;
+  }
+
+  VLOG(signals) << "Stack overflow found";
+
+  // Now arrange for the signal handler to return to art_quick_throw_stack_overflow_from.
+  // The value of RA must be the same as it was when we entered the code that
+  // caused this fault.  This will be inserted into a callee save frame by
+  // the function to which this handler returns (art_quick_throw_stack_overflow).
+  sc->sc_pc = reinterpret_cast<uintptr_t>(art_quick_throw_stack_overflow);
+  sc->sc_regs[25] = sc->sc_pc;          // make sure T9 points to the function
+
+  // The kernel will now return to the address in sc->arm_pc.
+  return true;
 }
 }       // namespace art
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 6c55129..1453e9f 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -921,6 +921,8 @@ bool Runtime::Init(const RuntimeOptions& raw_options, bool ignore_unrecognized)
     case kX86:
     case kArm64:
     case kX86_64:
+    case kMips:
+    case kMips64:
       implicit_null_checks_ = true;
       // Installing stack protection does not play well with valgrind.
       implicit_so_checks_ = (RUNNING_ON_VALGRIND == 0);
diff --git a/test/Android.run-test.mk b/test/Android.run-test.mk
index 89ed4c5..b043d46 100644
--- a/test/Android.run-test.mk
+++ b/test/Android.run-test.mk
@@ -428,9 +428,6 @@ TEST_ART_BROKEN_OPTIMIZING_ARM64_RUN_TESTS :=
 
 # Known broken tests for the MIPS64 optimizing compiler backend in 64-bit mode.  b/21555893
 TEST_ART_BROKEN_OPTIMIZING_MIPS64_64BIT_RUN_TESTS := \
-  004-SignalTest \
-  018-stack-overflow \
-  107-int-math2 \
   449-checker-bce
 
 ifeq ($(TARGET_ARCH),mips64)
@@ -443,20 +440,6 @@ endif
 
 TEST_ART_BROKEN_OPTIMIZING_MIPS64_64BIT_RUN_TESTS :=
 
-# Known broken tests for the MIPS64 optimizing compiler backend in 32-bit mode.  b/21555893
-TEST_ART_BROKEN_OPTIMIZING_MIPS64_32BIT_RUN_TESTS := \
-  496-checker-inlining-and-class-loader
-
-ifeq ($(TARGET_ARCH),mips64)
-  ifneq (,$(filter optimizing,$(COMPILER_TYPES)))
-    ART_TEST_KNOWN_BROKEN += $(call all-run-test-names,target,$(RUN_TYPES),$(PREBUILD_TYPES), \
-        optimizing,$(RELOCATE_TYPES),$(TRACE_TYPES),$(GC_TYPES),$(JNI_TYPES), \
-        $(IMAGE_TYPES),$(PICTEST_TYPES),$(DEBUGGABLE_TYPES),$(TEST_ART_BROKEN_OPTIMIZING_MIPS64_32BIT_RUN_TESTS),32)
-  endif
-endif
-
-TEST_ART_BROKEN_OPTIMIZING_MIPS64_32BIT_RUN_TESTS :=
-
 # Known broken tests for the optimizing compiler.
 TEST_ART_BROKEN_OPTIMIZING_RUN_TESTS :=