Revert "Revert "Pull the pthread_key_t functions out of pthread.c.""

This reverts commit 6260553d48f6fd87ca220270bea8bafdde5726ec

(Removing the accidental libm/Android.mk change.)

Change-Id: I6cddd9857c31facc05636e8221505b3d2344cb75

1 files changed, 280 insertions, 0 deletions

diff --git a/libc/bionic/pthread_key.cpp b/libc/bionic/pthread_key.cpp
new file mode 100644
index 0000000..00dacba
--- /dev/null
+++ b/libc/bionic/pthread_key.cpp
@@ -0,0 +1,280 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <malloc.h>
+#include <memory.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/atomics.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "bionic_atomic_inline.h"
+#include "bionic_futex.h"
+#include "bionic_pthread.h"
+#include "bionic_ssp.h"
+#include "bionic_tls.h"
+#include "debug_format.h"
+#include "pthread_internal.h"
+#include "thread_private.h"
+
+/* A technical note regarding our thread-local-storage (TLS) implementation:
+ *
+ * There can be up to BIONIC_TLS_SLOTS independent TLS keys in a given process,
+ * The keys below TLS_SLOT_FIRST_USER_SLOT are reserved for Bionic to hold
+ * special thread-specific variables like errno or a pointer to
+ * the current thread's descriptor. These entries cannot be accessed through
+ * pthread_getspecific() / pthread_setspecific() or pthread_key_delete()
+ *
+ * The 'tls_map_t' type defined below implements a shared global map of
+ * currently created/allocated TLS keys and the destructors associated
+ * with them.
+ *
+ * The global TLS map simply contains a bitmap of allocated keys, and
+ * an array of destructors.
+ *
+ * Each thread has a TLS area that is a simple array of BIONIC_TLS_SLOTS void*
+ * pointers. the TLS area of the main thread is stack-allocated in
+ * __libc_init_common, while the TLS area of other threads is placed at
+ * the top of their stack in pthread_create.
+ *
+ * When pthread_key_delete() is called it will erase the key's bitmap bit
+ * and its destructor, and will also clear the key data in the TLS area of
+ * all created threads. As mandated by Posix, it is the responsibility of
+ * the caller of pthread_key_delete() to properly reclaim the objects that
+ * were pointed to by these data fields (either before or after the call).
+ */
+
+#define TLSMAP_BITS       32
+#define TLSMAP_WORDS      ((BIONIC_TLS_SLOTS+TLSMAP_BITS-1)/TLSMAP_BITS)
+#define TLSMAP_WORD(m,k)  (m).map[(k)/TLSMAP_BITS]
+#define TLSMAP_MASK(k)    (1U << ((k)&(TLSMAP_BITS-1)))
+
+static inline bool IsValidUserKey(pthread_key_t key) {
+  return (key >= TLS_SLOT_FIRST_USER_SLOT && key < BIONIC_TLS_SLOTS);
+}
+
+typedef void (*key_destructor_t)(void*);
+
+struct tls_map_t {
+  bool is_initialized;
+
+  /* bitmap of allocated keys */
+  uint32_t map[TLSMAP_WORDS];
+
+  key_destructor_t key_destructors[BIONIC_TLS_SLOTS];
+};
+
+class ScopedTlsMapAccess {
+ public:
+  ScopedTlsMapAccess() {
+    Lock();
+
+    // If this is the first time the TLS map has been accessed,
+    // mark the slots belonging to well-known keys as being in use.
+    // This isn't currently necessary because the well-known keys
+    // can only be accessed directly by bionic itself, do not have
+    // destructors, and all the functions that touch the TLS map
+    // start after the maximum well-known slot.
+    if (!s_tls_map_.is_initialized) {
+      for (pthread_key_t key = 0; key < TLS_SLOT_FIRST_USER_SLOT; ++key) {
+        SetInUse(key, NULL);
+      }
+      s_tls_map_.is_initialized = true;
+    }
+  }
+
+  ~ScopedTlsMapAccess() {
+    Unlock();
+  }
+
+  int CreateKey(pthread_key_t* result, void (*key_destructor)(void*)) {
+    // Take the first unallocated key.
+    for (int key = 0; key < BIONIC_TLS_SLOTS; ++key) {
+      if (!IsInUse(key)) {
+        SetInUse(key, key_destructor);
+        *result = key;
+        return 0;
+      }
+    }
+
+    // We hit PTHREAD_KEYS_MAX. POSIX says EAGAIN for this case.
+    return EAGAIN;
+  }
+
+  void DeleteKey(pthread_key_t key) {
+    TLSMAP_WORD(s_tls_map_, key) &= ~TLSMAP_MASK(key);
+    s_tls_map_.key_destructors[key] = NULL;
+  }
+
+  bool IsInUse(pthread_key_t key) {
+    return (TLSMAP_WORD(s_tls_map_, key) & TLSMAP_MASK(key)) != 0;
+  }
+
+  void SetInUse(pthread_key_t key, void (*key_destructor)(void*)) {
+    TLSMAP_WORD(s_tls_map_, key) |= TLSMAP_MASK(key);
+    s_tls_map_.key_destructors[key] = key_destructor;
+  }
+
+  // Called from pthread_exit() to remove all TLS key data
+  // from this thread's TLS area. This must call the destructor of all keys
+  // that have a non-NULL data value and a non-NULL destructor.
+  void CleanAll() {
+    void** tls = (void**)__get_tls();
+
+    // Because destructors can do funky things like deleting/creating other
+    // keys, we need to implement this in a loop.
+    for (int rounds = PTHREAD_DESTRUCTOR_ITERATIONS; rounds > 0; --rounds) {
+      size_t called_destructor_count = 0;
+      for (int key = 0; key < BIONIC_TLS_SLOTS; ++key) {
+        if (IsInUse(key)) {
+          void* data = tls[key];
+          void (*key_destructor)(void*) = s_tls_map_.key_destructors[key];
+
+          if (data != NULL && key_destructor != NULL) {
+            // we need to clear the key data now, this will prevent the
+            // destructor (or a later one) from seeing the old value if
+            // it calls pthread_getspecific() for some odd reason
+
+            // we do not do this if 'key_destructor == NULL' just in case another
+            // destructor function might be responsible for manually
+            // releasing the corresponding data.
+            tls[key] = NULL;
+
+            // because the destructor is free to call pthread_key_create
+            // and/or pthread_key_delete, we need to temporarily unlock
+            // the TLS map
+            Unlock();
+            (*key_destructor)(data);
+            Lock();
+            ++called_destructor_count;
+          }
+        }
+      }
+
+      // If we didn't call any destructors, there is no need to check the TLS data again.
+      if (called_destructor_count == 0) {
+        break;
+      }
+    }
+  }
+
+ private:
+  static tls_map_t s_tls_map_;
+  static pthread_mutex_t s_tls_map_lock_;
+
+  void Lock() {
+    pthread_mutex_lock(&s_tls_map_lock_);
+  }
+
+  void Unlock() {
+    pthread_mutex_unlock(&s_tls_map_lock_);
+  }
+};
+
+tls_map_t ScopedTlsMapAccess::s_tls_map_;
+pthread_mutex_t ScopedTlsMapAccess::s_tls_map_lock_;
+
+__LIBC_HIDDEN__ void pthread_key_clean_all() {
+  ScopedTlsMapAccess tls_map;
+  tls_map.CleanAll();
+}
+
+int pthread_key_create(pthread_key_t* key, void (*key_destructor)(void*)) {
+  ScopedTlsMapAccess tls_map;
+  return tls_map.CreateKey(key, key_destructor);
+}
+
+// Deletes a pthread_key_t. note that the standard mandates that this does
+// not call the destructors for non-NULL key values. Instead, it is the
+// responsibility of the caller to properly dispose of the corresponding data
+// and resources, using any means it finds suitable.
+int pthread_key_delete(pthread_key_t key) {
+  ScopedTlsMapAccess tls_map;
+
+  if (!IsValidUserKey(key) || !tls_map.IsInUse(key)) {
+    return EINVAL;
+  }
+
+  // Clear value in all threads.
+  pthread_mutex_lock(&gThreadListLock);
+  for (pthread_internal_t*  t = gThreadList; t != NULL; t = t->next) {
+    // Avoid zombie threads with a negative 'join_count'. These are really
+    // already dead and don't have a TLS area anymore.
+
+    // Similarly, it is possible to have t->tls == NULL for threads that
+    // were just recently created through pthread_create() but whose
+    // startup trampoline (__thread_entry) hasn't been run yet by the
+    // scheduler. t->tls will also be NULL after it's stack has been
+    // unmapped but before the ongoing pthread_join() is finished.
+    // so check for this too.
+    if (t->join_count < 0 || !t->tls) {
+      continue;
+    }
+
+    t->tls[key] = NULL;
+  }
+  tls_map.DeleteKey(key);
+
+  pthread_mutex_unlock(&gThreadListLock);
+  return 0;
+}
+
+void* pthread_getspecific(pthread_key_t key) {
+  if (!IsValidUserKey(key)) {
+    return NULL;
+  }
+
+  // For performance reasons, we do not lock/unlock the global TLS map
+  // to check that the key is properly allocated. If the key was not
+  // allocated, the value read from the TLS should always be NULL
+  // due to pthread_key_delete() clearing the values for all threads.
+  return (void *)(((unsigned *)__get_tls())[key]);
+}
+
+int pthread_setspecific(pthread_key_t key, const void* ptr) {
+  ScopedTlsMapAccess tls_map;
+
+  if (!IsValidUserKey(key) || !tls_map.IsInUse(key)) {
+    return EINVAL;
+  }
+
+  ((uint32_t *)__get_tls())[key] = (uint32_t)ptr;
+  return 0;
+}