1 files changed, 375 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/tsan/rtl/tsan_fd.cpp b/contrib/llvm-project/compiler-rt/lib/tsan/rtl/tsan_fd.cpp
new file mode 100644
index 000000000000..ab295a69dce1
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/tsan/rtl/tsan_fd.cpp
@@ -0,0 +1,375 @@
+//===-- tsan_fd.cpp -------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+//===----------------------------------------------------------------------===//
+
+#include "tsan_fd.h"
+
+#include <sanitizer_common/sanitizer_atomic.h>
+
+#include "tsan_interceptors.h"
+#include "tsan_rtl.h"
+
+namespace __tsan {
+
+const int kTableSizeL1 = 1024;
+const int kTableSizeL2 = 1024;
+const int kTableSize = kTableSizeL1 * kTableSizeL2;
+
+struct FdSync {
+  atomic_uint64_t rc;
+};
+
+struct FdDesc {
+  FdSync *sync;
+  // This is used to establish write -> epoll_wait synchronization
+  // where epoll_wait receives notification about the write.
+  atomic_uintptr_t aux_sync;  // FdSync*
+  Tid creation_tid;
+  StackID creation_stack;
+  bool closed;
+};
+
+struct FdContext {
+  atomic_uintptr_t tab[kTableSizeL1];
+  // Addresses used for synchronization.
+  FdSync globsync;
+  FdSync filesync;
+  FdSync socksync;
+  u64 connectsync;
+};
+
+static FdContext fdctx;
+
+static bool bogusfd(int fd) {
+  // Apparently a bogus fd value.
+  return fd < 0 || fd >= kTableSize;
+}
+
+static FdSync *allocsync(ThreadState *thr, uptr pc) {
+  FdSync *s = (FdSync*)user_alloc_internal(thr, pc, sizeof(FdSync),
+      kDefaultAlignment, false);
+  atomic_store(&s->rc, 1, memory_order_relaxed);
+  return s;
+}
+
+static FdSync *ref(FdSync *s) {
+  if (s && atomic_load(&s->rc, memory_order_relaxed) != (u64)-1)
+    atomic_fetch_add(&s->rc, 1, memory_order_relaxed);
+  return s;
+}
+
+static void unref(ThreadState *thr, uptr pc, FdSync *s) {
+  if (s && atomic_load(&s->rc, memory_order_relaxed) != (u64)-1) {
+    if (atomic_fetch_sub(&s->rc, 1, memory_order_acq_rel) == 1) {
+      CHECK_NE(s, &fdctx.globsync);
+      CHECK_NE(s, &fdctx.filesync);
+      CHECK_NE(s, &fdctx.socksync);
+      user_free(thr, pc, s, false);
+    }
+  }
+}
+
+static FdDesc *fddesc(ThreadState *thr, uptr pc, int fd) {
+  CHECK_GE(fd, 0);
+  CHECK_LT(fd, kTableSize);
+  atomic_uintptr_t *pl1 = &fdctx.tab[fd / kTableSizeL2];
+  uptr l1 = atomic_load(pl1, memory_order_consume);
+  if (l1 == 0) {
+    uptr size = kTableSizeL2 * sizeof(FdDesc);
+    // We need this to reside in user memory to properly catch races on it.
+    void *p = user_alloc_internal(thr, pc, size, kDefaultAlignment, false);
+    internal_memset(p, 0, size);
+    MemoryResetRange(thr, (uptr)&fddesc, (uptr)p, size);
+    if (atomic_compare_exchange_strong(pl1, &l1, (uptr)p, memory_order_acq_rel))
+      l1 = (uptr)p;
+    else
+      user_free(thr, pc, p, false);
+  }
+  FdDesc *fds = reinterpret_cast<FdDesc *>(l1);
+  return &fds[fd % kTableSizeL2];
+}
+
+// pd must be already ref'ed.
+static void init(ThreadState *thr, uptr pc, int fd, FdSync *s,
+    bool write = true) {
+  FdDesc *d = fddesc(thr, pc, fd);
+  // As a matter of fact, we don't intercept all close calls.
+  // See e.g. libc __res_iclose().
+  if (d->sync) {
+    unref(thr, pc, d->sync);
+    d->sync = 0;
+  }
+  unref(thr, pc,
+        reinterpret_cast<FdSync *>(
+            atomic_load(&d->aux_sync, memory_order_relaxed)));
+  atomic_store(&d->aux_sync, 0, memory_order_relaxed);
+  if (flags()->io_sync == 0) {
+    unref(thr, pc, s);
+  } else if (flags()->io_sync == 1) {
+    d->sync = s;
+  } else if (flags()->io_sync == 2) {
+    unref(thr, pc, s);
+    d->sync = &fdctx.globsync;
+  }
+  d->creation_tid = thr->tid;
+  d->creation_stack = CurrentStackId(thr, pc);
+  d->closed = false;
+  // This prevents false positives on fd_close_norace3.cpp test.
+  // The mechanics of the false positive are not completely clear,
+  // but it happens only if global reset is enabled (flush_memory_ms=1)
+  // and may be related to lost writes during asynchronous MADV_DONTNEED.
+  SlotLocker locker(thr);
+  if (write) {
+    // To catch races between fd usage and open.
+    MemoryRangeImitateWrite(thr, pc, (uptr)d, 8);
+  } else {
+    // See the dup-related comment in FdClose.
+    MemoryAccess(thr, pc, (uptr)d, 8, kAccessRead | kAccessSlotLocked);
+  }
+}
+
+void FdInit() {
+  atomic_store(&fdctx.globsync.rc, (u64)-1, memory_order_relaxed);
+  atomic_store(&fdctx.filesync.rc, (u64)-1, memory_order_relaxed);
+  atomic_store(&fdctx.socksync.rc, (u64)-1, memory_order_relaxed);
+}
+
+void FdOnFork(ThreadState *thr, uptr pc) {
+  // On fork() we need to reset all fd's, because the child is going
+  // close all them, and that will cause races between previous read/write
+  // and the close.
+  for (int l1 = 0; l1 < kTableSizeL1; l1++) {
+    FdDesc *tab = (FdDesc*)atomic_load(&fdctx.tab[l1], memory_order_relaxed);
+    if (tab == 0)
+      break;
+    for (int l2 = 0; l2 < kTableSizeL2; l2++) {
+      FdDesc *d = &tab[l2];
+      MemoryResetRange(thr, pc, (uptr)d, 8);
+    }
+  }
+}
+
+bool FdLocation(uptr addr, int *fd, Tid *tid, StackID *stack, bool *closed) {
+  for (int l1 = 0; l1 < kTableSizeL1; l1++) {
+    FdDesc *tab = (FdDesc*)atomic_load(&fdctx.tab[l1], memory_order_relaxed);
+    if (tab == 0)
+      break;
+    if (addr >= (uptr)tab && addr < (uptr)(tab + kTableSizeL2)) {
+      int l2 = (addr - (uptr)tab) / sizeof(FdDesc);
+      FdDesc *d = &tab[l2];
+      *fd = l1 * kTableSizeL1 + l2;
+      *tid = d->creation_tid;
+      *stack = d->creation_stack;
+      *closed = d->closed;
+      return true;
+    }
+  }
+  return false;
+}
+
+void FdAcquire(ThreadState *thr, uptr pc, int fd) {
+  if (bogusfd(fd))
+    return;
+  FdDesc *d = fddesc(thr, pc, fd);
+  FdSync *s = d->sync;
+  DPrintf("#%d: FdAcquire(%d) -> %p\n", thr->tid, fd, s);
+  MemoryAccess(thr, pc, (uptr)d, 8, kAccessRead);
+  if (s)
+    Acquire(thr, pc, (uptr)s);
+}
+
+void FdRelease(ThreadState *thr, uptr pc, int fd) {
+  if (bogusfd(fd))
+    return;
+  FdDesc *d = fddesc(thr, pc, fd);
+  FdSync *s = d->sync;
+  DPrintf("#%d: FdRelease(%d) -> %p\n", thr->tid, fd, s);
+  MemoryAccess(thr, pc, (uptr)d, 8, kAccessRead);
+  if (s)
+    Release(thr, pc, (uptr)s);
+  if (uptr aux_sync = atomic_load(&d->aux_sync, memory_order_acquire))
+    Release(thr, pc, aux_sync);
+}
+
+void FdAccess(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdAccess(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  FdDesc *d = fddesc(thr, pc, fd);
+  MemoryAccess(thr, pc, (uptr)d, 8, kAccessRead);
+}
+
+void FdClose(ThreadState *thr, uptr pc, int fd, bool write) {
+  DPrintf("#%d: FdClose(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  FdDesc *d = fddesc(thr, pc, fd);
+  {
+    // Need to lock the slot to make MemoryAccess and MemoryResetRange atomic
+    // with respect to global reset. See the comment in MemoryRangeFreed.
+    SlotLocker locker(thr);
+    if (!MustIgnoreInterceptor(thr)) {
+      if (write) {
+        // To catch races between fd usage and close.
+        MemoryAccess(thr, pc, (uptr)d, 8,
+                     kAccessWrite | kAccessCheckOnly | kAccessSlotLocked);
+      } else {
+        // This path is used only by dup2/dup3 calls.
+        // We do read instead of write because there is a number of legitimate
+        // cases where write would lead to false positives:
+        // 1. Some software dups a closed pipe in place of a socket before
+        // closing
+        //    the socket (to prevent races actually).
+        // 2. Some daemons dup /dev/null in place of stdin/stdout.
+        // On the other hand we have not seen cases when write here catches real
+        // bugs.
+        MemoryAccess(thr, pc, (uptr)d, 8,
+                     kAccessRead | kAccessCheckOnly | kAccessSlotLocked);
+      }
+    }
+    // We need to clear it, because if we do not intercept any call out there
+    // that creates fd, we will hit false postives.
+    MemoryResetRange(thr, pc, (uptr)d, 8);
+  }
+  unref(thr, pc, d->sync);
+  d->sync = 0;
+  unref(thr, pc,
+        reinterpret_cast<FdSync *>(
+            atomic_load(&d->aux_sync, memory_order_relaxed)));
+  atomic_store(&d->aux_sync, 0, memory_order_relaxed);
+  d->closed = true;
+  d->creation_tid = thr->tid;
+  d->creation_stack = CurrentStackId(thr, pc);
+}
+
+void FdFileCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdFileCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, &fdctx.filesync);
+}
+
+void FdDup(ThreadState *thr, uptr pc, int oldfd, int newfd, bool write) {
+  DPrintf("#%d: FdDup(%d, %d)\n", thr->tid, oldfd, newfd);
+  if (bogusfd(oldfd) || bogusfd(newfd))
+    return;
+  // Ignore the case when user dups not yet connected socket.
+  FdDesc *od = fddesc(thr, pc, oldfd);
+  MemoryAccess(thr, pc, (uptr)od, 8, kAccessRead);
+  FdClose(thr, pc, newfd, write);
+  init(thr, pc, newfd, ref(od->sync), write);
+}
+
+void FdPipeCreate(ThreadState *thr, uptr pc, int rfd, int wfd) {
+  DPrintf("#%d: FdCreatePipe(%d, %d)\n", thr->tid, rfd, wfd);
+  FdSync *s = allocsync(thr, pc);
+  init(thr, pc, rfd, ref(s));
+  init(thr, pc, wfd, ref(s));
+  unref(thr, pc, s);
+}
+
+void FdEventCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdEventCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, allocsync(thr, pc));
+}
+
+void FdSignalCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdSignalCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, 0);
+}
+
+void FdInotifyCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdInotifyCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, 0);
+}
+
+void FdPollCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdPollCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, allocsync(thr, pc));
+}
+
+void FdPollAdd(ThreadState *thr, uptr pc, int epfd, int fd) {
+  DPrintf("#%d: FdPollAdd(%d, %d)\n", thr->tid, epfd, fd);
+  if (bogusfd(epfd) || bogusfd(fd))
+    return;
+  FdDesc *d = fddesc(thr, pc, fd);
+  // Associate fd with epoll fd only once.
+  // While an fd can be associated with multiple epolls at the same time,
+  // or with different epolls during different phases of lifetime,
+  // synchronization semantics (and examples) of this are unclear.
+  // So we don't support this for now.
+  // If we change the association, it will also create lifetime management
+  // problem for FdRelease which accesses the aux_sync.
+  if (atomic_load(&d->aux_sync, memory_order_relaxed))
+    return;
+  FdDesc *epd = fddesc(thr, pc, epfd);
+  FdSync *s = epd->sync;
+  if (!s)
+    return;
+  uptr cmp = 0;
+  if (atomic_compare_exchange_strong(
+          &d->aux_sync, &cmp, reinterpret_cast<uptr>(s), memory_order_release))
+    ref(s);
+}
+
+void FdSocketCreate(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdSocketCreate(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  // It can be a UDP socket.
+  init(thr, pc, fd, &fdctx.socksync);
+}
+
+void FdSocketAccept(ThreadState *thr, uptr pc, int fd, int newfd) {
+  DPrintf("#%d: FdSocketAccept(%d, %d)\n", thr->tid, fd, newfd);
+  if (bogusfd(fd))
+    return;
+  // Synchronize connect->accept.
+  Acquire(thr, pc, (uptr)&fdctx.connectsync);
+  init(thr, pc, newfd, &fdctx.socksync);
+}
+
+void FdSocketConnecting(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdSocketConnecting(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  // Synchronize connect->accept.
+  Release(thr, pc, (uptr)&fdctx.connectsync);
+}
+
+void FdSocketConnect(ThreadState *thr, uptr pc, int fd) {
+  DPrintf("#%d: FdSocketConnect(%d)\n", thr->tid, fd);
+  if (bogusfd(fd))
+    return;
+  init(thr, pc, fd, &fdctx.socksync);
+}
+
+uptr File2addr(const char *path) {
+  (void)path;
+  static u64 addr;
+  return (uptr)&addr;
+}
+
+uptr Dir2addr(const char *path) {
+  (void)path;
+  static u64 addr;
+  return (uptr)&addr;
+}
+
+}  //  namespace __tsan