[scudo] Enabling MIPS support for Scudo

Adding MIPS 32-bit and 64-bit support for Scudo.

Reviewed by cryptoad, sdardis.
Differential: D31803


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@305682 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 83 insertions, 8 deletions

diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index ae2a262a1..0da98b9a4 100644
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -179,7 +179,7 @@ set(ALL_UBSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
 set(ALL_SAFESTACK_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM64} ${MIPS32} ${MIPS64})
 set(ALL_CFI_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64})
 set(ALL_ESAN_SUPPORTED_ARCH ${X86_64} ${MIPS64})
-set(ALL_SCUDO_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64})
+set(ALL_SCUDO_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${MIPS32} ${MIPS64})
 set(ALL_XRAY_SUPPORTED_ARCH ${X86_64} ${ARM32} ${ARM64} ${MIPS32} ${MIPS64} powerpc64le)
 
 if(APPLE)
diff --git a/lib/sanitizer_common/sanitizer_atomic_clang.h b/lib/sanitizer_common/sanitizer_atomic_clang.h
index 38363e875..47581282a 100644
--- a/lib/sanitizer_common/sanitizer_atomic_clang.h
+++ b/lib/sanitizer_common/sanitizer_atomic_clang.h
@@ -71,16 +71,26 @@ INLINE typename T::Type atomic_exchange(volatile T *a,
   return v;
 }
 
-template<typename T>
-INLINE bool atomic_compare_exchange_strong(volatile T *a,
-                                           typename T::Type *cmp,
+template <typename T>
+INLINE bool atomic_compare_exchange_strong(volatile T *a, typename T::Type *cmp,
                                            typename T::Type xchg,
                                            memory_order mo) {
   typedef typename T::Type Type;
   Type cmpv = *cmp;
-  Type prev = __sync_val_compare_and_swap(&a->val_dont_use, cmpv, xchg);
-  if (prev == cmpv)
-    return true;
+  Type prev;
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIO32
+  if (sizeof(*a) == 8) {
+    Type volatile *val_ptr = const_cast<Type volatile *>(&a->val_dont_use);
+    prev = __mips_sync_val_compare_and_swap<u64>(
+        reinterpret_cast<u64 volatile *>(val_ptr), reinterpret_cast<u64> cmpv,
+        reinterpret_cast<u64> xchg);
+  } else {
+    prev = __sync_val_compare_and_swap(&a->val_dont_use, cmpv, xchg);
+  }
+#else
+  prev = __sync_val_compare_and_swap(&a->val_dont_use, cmpv, xchg);
+#endif
+  if (prev == cmpv) return true;
   *cmp = prev;
   return false;
 }
diff --git a/lib/sanitizer_common/sanitizer_atomic_clang_other.h b/lib/sanitizer_common/sanitizer_atomic_clang_other.h
index 099b9f7ec..2825c7400 100644
--- a/lib/sanitizer_common/sanitizer_atomic_clang_other.h
+++ b/lib/sanitizer_common/sanitizer_atomic_clang_other.h
@@ -17,6 +17,56 @@
 
 namespace __sanitizer {
 
+// MIPS32 does not support atomic > 4 bytes. To address this lack of
+// functionality, the sanitizer library provides helper methods which use an
+// internal spin lock mechanism to emulate atomic oprations when the size is
+// 8 bytes.
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIO32
+static void __spin_lock(volatile int *lock) {
+  while (__sync_lock_test_and_set(lock, 1))
+    while (*lock) {
+    }
+}
+
+static void __spin_unlock(volatile int *lock) { __sync_lock_release(lock); }
+
+
+// Make sure the lock is on its own cache line to prevent false sharing.
+// Put it inside a struct that is aligned and padded to the typical MIPS
+// cacheline which is 32 bytes.
+static struct {
+  int lock;
+  char pad[32 - sizeof(int)];
+} __attribute__((aligned(32))) lock = {0};
+
+template <class T>
+T __mips_sync_fetch_and_add(volatile T *ptr, T val) {
+  T ret;
+
+  __spin_lock(&lock.lock);
+
+  ret = *ptr;
+  *ptr = ret + val;
+
+  __spin_unlock(&lock.lock);
+
+  return ret;
+}
+
+template <class T>
+T __mips_sync_val_compare_and_swap(volatile T *ptr, T oldval, T newval) {
+  T ret;
+  __spin_lock(&lock.lock);
+
+  ret = *ptr;
+  if (ret == oldval) *ptr = newval;
+
+  __spin_unlock(&lock.lock);
+
+  return ret;
+}
+#endif
+
 INLINE void proc_yield(int cnt) {
   __asm__ __volatile__("" ::: "memory");
 }
@@ -53,8 +103,15 @@ INLINE typename T::Type atomic_load(
     // 64-bit load on 32-bit platform.
     // Gross, but simple and reliable.
     // Assume that it is not in read-only memory.
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIO32
+    typename T::Type volatile *val_ptr =
+        const_cast<typename T::Type volatile *>(&a->val_dont_use);
+    v = __mips_sync_fetch_and_add<u64>(
+        reinterpret_cast<u64 volatile *>(val_ptr), 0);
+#else
     v = __sync_fetch_and_add(
         const_cast<typename T::Type volatile *>(&a->val_dont_use), 0);
+#endif
   }
   return v;
 }
@@ -84,7 +141,15 @@ INLINE void atomic_store(volatile T *a, typename T::Type v, memory_order mo) {
     typename T::Type cmp = a->val_dont_use;
     typename T::Type cur;
     for (;;) {
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIO32
+      typename T::Type volatile *val_ptr =
+          const_cast<typename T::Type volatile *>(&a->val_dont_use);
+      cur = __mips_sync_val_compare_and_swap<u64>(
+          reinterpret_cast<u64 volatile *>(val_ptr), reinterpret_cast<u64> cmp,
+          reinterpret_cast<u64> v);
+#else
       cur = __sync_val_compare_and_swap(&a->val_dont_use, cmp, v);
+#endif
       if (cmp == v)
         break;
       cmp = cur;
diff --git a/test/scudo/random_shuffle.cpp b/test/scudo/random_shuffle.cpp
index 41e67ded6..05a432615 100644
--- a/test/scudo/random_shuffle.cpp
+++ b/test/scudo/random_shuffle.cpp
@@ -7,7 +7,7 @@
 // RUN: %run %t 10000 > %T/random_shuffle_tmp_dir/out2
 // RUN: not diff %T/random_shuffle_tmp_dir/out?
 // RUN: rm -rf %T/random_shuffle_tmp_dir
-// UNSUPPORTED: i386-linux,i686-linux,arm-linux,armhf-linux,aarch64-linux
+// UNSUPPORTED: i386-linux,i686-linux,arm-linux,armhf-linux,aarch64-linux,mips-linux,mipsel-linux,mips64-linux,mips64el-linux
 
 // Tests that the allocator shuffles the chunks before returning to the user.