[scudo] Scudo thread specific data refactor, part 3

Summary:
Previous parts: D38139, D38183.

In this part of the refactor, we abstract the Linux vs Android TSD dissociation
in favor of a Exclusive vs Shared one, allowing for easier platform introduction
and configuration.

Most of this change consist of shuffling the files around to reflect the new
organization.

We introduce `scudo_platform.h` where platform specific definition lie. This
involves the TSD model and the platform specific allocator parameters. In an
upcoming CL, those will be configurable via defines, but we currently stick
with conservative defaults.

Reviewers: alekseyshl, dvyukov

Reviewed By: alekseyshl, dvyukov

Subscribers: srhines, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D38244

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@314224 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/scudo/scudo_tsd_shared.cpp b/lib/scudo/scudo_tsd_shared.cpp
new file mode 100644
index 000000000..481635e6a
--- /dev/null
+++ b/lib/scudo/scudo_tsd_shared.cpp
@@ -0,0 +1,96 @@
+//===-- scudo_tsd_shared.cpp ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// Scudo shared TSD implementation.
+///
+//===----------------------------------------------------------------------===//
+
+#include "scudo_tsd.h"
+
+#if !SCUDO_TSD_EXCLUSIVE
+
+#include <pthread.h>
+
+namespace __scudo {
+
+static pthread_once_t GlobalInitialized = PTHREAD_ONCE_INIT;
+static pthread_key_t PThreadKey;
+
+static atomic_uint32_t CurrentIndex;
+static ScudoTSD *TSDs;
+static u32 NumberOfTSDs;
+
+// sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used as they allocate memory.
+static uptr getNumberOfCPUs() {
+  cpu_set_t CPUs;
+  CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
+  return CPU_COUNT(&CPUs);
+}
+
+static void initOnce() {
+  // Hack: TLS_SLOT_TSAN was introduced in N. To be able to use it on M for
+  // testing, we create an unused key. Since the key_data array follows the tls
+  // array, it basically gives us the extra entry we need.
+  // TODO(kostyak): remove and restrict to N and above.
+  CHECK_EQ(pthread_key_create(&PThreadKey, NULL), 0);
+  initScudo();
+  NumberOfTSDs = getNumberOfCPUs();
+  if (NumberOfTSDs == 0)
+    NumberOfTSDs = 1;
+  if (NumberOfTSDs > 32)
+    NumberOfTSDs = 32;
+  TSDs = reinterpret_cast<ScudoTSD *>(
+      MmapOrDie(sizeof(ScudoTSD) * NumberOfTSDs, "ScudoTSDs"));
+  for (u32 i = 0; i < NumberOfTSDs; i++)
+    TSDs[i].init(/*Shared=*/true);
+}
+
+void initThread(bool MinimalInit) {
+  pthread_once(&GlobalInitialized, initOnce);
+  // Initial context assignment is done in a plain round-robin fashion.
+  u32 Index = atomic_fetch_add(&CurrentIndex, 1, memory_order_relaxed);
+  ScudoTSD *TSD = &TSDs[Index % NumberOfTSDs];
+  *get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
+}
+
+ScudoTSD *getTSDAndLockSlow() {
+  ScudoTSD *TSD;
+  if (NumberOfTSDs > 1) {
+    // Go through all the contexts and find the first unlocked one.
+    for (u32 i = 0; i < NumberOfTSDs; i++) {
+      TSD = &TSDs[i];
+      if (TSD->tryLock()) {
+        *get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
+        return TSD;
+      }
+    }
+    // No luck, find the one with the lowest Precedence, and slow lock it.
+    u64 LowestPrecedence = UINT64_MAX;
+    for (u32 i = 0; i < NumberOfTSDs; i++) {
+      u64 Precedence = TSDs[i].getPrecedence();
+      if (Precedence && Precedence < LowestPrecedence) {
+        TSD = &TSDs[i];
+        LowestPrecedence = Precedence;
+      }
+    }
+    if (LIKELY(LowestPrecedence != UINT64_MAX)) {
+      TSD->lock();
+      *get_android_tls_ptr() = reinterpret_cast<uptr>(TSD);
+      return TSD;
+    }
+  }
+  // Last resort, stick with the current one.
+  TSD = reinterpret_cast<ScudoTSD *>(*get_android_tls_ptr());
+  TSD->lock();
+  return TSD;
+}
+
+}  // namespace __scudo
+
+#endif  // !SCUDO_TSD_EXCLUSIVE