- a0673e81da7ee7e322283e518331a4cdaeca837b Internal change by Abseil Team <absl-team@google.com>

  - 537e863510a423968c2d319263dd1c100695a2e9 Add internal-only functionality to examine the stack, to ... by Derek Mauro <dmauro@google.com>
  - 1ded12406d8b8fd7be910c8dfe8c2a8edf66136e Explicitly suppress the default move constructor and assi... by Derek Mauro <dmauro@google.com>
  - 347d38447ebc38e5d33fec6b67988880eb3cd249 Move implementation detail do_mmap64 to a new file. by Greg Falcon <gfalcon@google.com>

GitOrigin-RevId: a0673e81da7ee7e322283e518331a4cdaeca837b
Change-Id: I5a347d34d5173082b3a78eb53432481b32c94b69

2 files changed, 159 insertions, 82 deletions

diff --git a/absl/base/internal/direct_mmap.h b/absl/base/internal/direct_mmap.h
new file mode 100644
index 000000000000..87576df6ee5b
--- /dev/null
+++ b/absl/base/internal/direct_mmap.h
@@ -0,0 +1,145 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Functions for directly invoking mmap() via syscall, avoiding the case where
+// mmap() has been locally overridden.
+
+#ifndef ABSL_BASE_INTERNAL_DIRECT_MMAP_H_
+#define ABSL_BASE_INTERNAL_DIRECT_MMAP_H_
+
+#include "absl/base/config.h"
+
+#if ABSL_HAVE_MMAP
+
+#include <sys/mman.h>
+
+#ifdef __linux__
+
+#include <sys/types.h>
+#ifdef __BIONIC__
+#include <sys/syscall.h>
+#else
+#include <syscall.h>
+#endif
+
+#include <linux/unistd.h>
+#include <unistd.h>
+#include <cerrno>
+#include <cstdarg>
+#include <cstdint>
+
+#ifdef __mips__
+// Include definitions of the ABI currently in use.
+#ifdef __BIONIC__
+// Android doesn't have sgidefs.h, but does have asm/sgidefs.h, which has the
+// definitions we need.
+#include <asm/sgidefs.h>
+#else
+#include <sgidefs.h>
+#endif  // __BIONIC__
+#endif  // __mips__
+
+// SYS_mmap and SYS_munmap are not defined in Android.
+#ifdef __BIONIC__
+extern "C" void* __mmap2(void*, size_t, int, int, int, long);
+#if defined(__NR_mmap) && !defined(SYS_mmap)
+#define SYS_mmap __NR_mmap
+#endif
+#ifndef SYS_munmap
+#define SYS_munmap __NR_munmap
+#endif
+#endif  // __BIONIC__
+
+namespace absl {
+namespace base_internal {
+
+// Platform specific logic extracted from
+// https://chromium.googlesource.com/linux-syscall-support/+/master/linux_syscall_support.h
+inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
+                        off64_t offset) __THROW {
+#if defined(__i386__) || defined(__ARM_ARCH_3__) || defined(__ARM_EABI__) || \
+    (defined(__mips__) && _MIPS_SIM == _MIPS_SIM_ABI32) ||                   \
+    (defined(__PPC__) && !defined(__PPC64__)) ||                             \
+    (defined(__s390__) && !defined(__s390x__))
+  // On these architectures, implement mmap with mmap2.
+  static int pagesize = 0;
+  if (pagesize == 0) {
+    pagesize = getpagesize();
+  }
+  if (offset < 0 || offset % pagesize != 0) {
+    errno = EINVAL;
+    return MAP_FAILED;
+  }
+#ifdef __BIONIC__
+  // SYS_mmap2 has problems on Android API level <= 16.
+  // Workaround by invoking __mmap2() instead.
+  return __mmap2(start, length, prot, flags, fd, offset / pagesize);
+#else
+  return reinterpret_cast<void*>(
+      syscall(SYS_mmap2, start, length, prot, flags, fd,
+              static_cast<off_t>(offset / pagesize)));
+#endif
+#elif defined(__s390x__)
+  // On s390x, mmap() arguments are passed in memory.
+  uint32_t buf[6] = {
+      reinterpret_cast<uint32_t>(start), static_cast<uint32_t>(length),
+      static_cast<uint32_t>(prot),       static_cast<uint32_t>(flags),
+      static_cast<uint32_t>(fd),         static_cast<uint32_t>(offset)};
+  return reintrepret_cast<void*>(syscall(SYS_mmap, buf));
+#elif defined(__x86_64__)
+// The x32 ABI has 32 bit longs, but the syscall interface is 64 bit.
+// We need to explicitly cast to an unsigned 64 bit type to avoid implicit
+// sign extension.  We can't cast pointers directly because those are
+// 32 bits, and gcc will dump ugly warnings about casting from a pointer
+// to an integer of a different size. We also need to make sure __off64_t
+// isn't truncated to 32-bits under x32.
+#define MMAP_SYSCALL_ARG(x) ((uint64_t)(uintptr_t)(x))
+  return reinterpret_cast<void*>(
+      syscall(SYS_mmap, MMAP_SYSCALL_ARG(start), MMAP_SYSCALL_ARG(length),
+              MMAP_SYSCALL_ARG(prot), MMAP_SYSCALL_ARG(flags),
+              MMAP_SYSCALL_ARG(fd), static_cast<uint64_t>(offset)));
+#undef MMAP_SYSCALL_ARG
+#else  // Remaining 64-bit aritectures.
+  static_assert(sizeof(unsigned long) == 8, "Platform is not 64-bit");
+  return reinterpret_cast<void*>(
+      syscall(SYS_mmap, start, length, prot, flags, fd, offset));
+#endif
+}
+
+inline int DirectMunmap(void* start, size_t length) {
+  return static_cast<int>(syscall(SYS_munmap, start, length));
+}
+
+}  // namespace base_internal
+}  // namespace absl
+
+#else  // !__linux__
+
+// For non-linux platforms where we have mmap, just dispatch directly to the
+// actual mmap()/munmap() methods.
+
+inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
+                        off_t offset) {
+  return mmap(start, length, prot, flags, fd, offset);
+}
+
+inline int DirectMunmap(void* start, size_t length) {
+  return munmap(start, length);
+}
+
+#endif  // __linux__
+
+#endif  // ABSL_HAVE_MMAP
+
+#endif  // ABSL_BASE_INTERNAL_DIRECT_MMAP_H_
diff --git a/absl/base/internal/malloc_hook_mmap_linux.inc b/absl/base/internal/malloc_hook_mmap_linux.inc
index 059ded57626d..b87621a68a47 100644
--- a/absl/base/internal/malloc_hook_mmap_linux.inc
+++ b/absl/base/internal/malloc_hook_mmap_linux.inc
@@ -35,89 +35,18 @@
 #include <cstdarg>
 #include <cstdint>
 
-#ifdef __mips__
-// Include definitions of the ABI currently in use.
-#ifdef __BIONIC__
-// Android doesn't have sgidefs.h, but does have asm/sgidefs.h, which has the
-// definitions we need.
-#include <asm/sgidefs.h>
-#else
-#include <sgidefs.h>
-#endif  // __BIONIC__
-#endif  // __mips__
+#include "absl/base/internal/direct_mmap.h"
 
-// SYS_mmap, SYS_munmap, and SYS_mremap are not defined in Android.
+// SYS_mremap is not defined in Android.
 #ifdef __BIONIC__
-extern "C" void *__mmap2(void *, size_t, int, int, int, long);
-#if defined(__NR_mmap) && !defined(SYS_mmap)
-#define SYS_mmap __NR_mmap
-#endif
-#ifndef SYS_munmap
-#define SYS_munmap __NR_munmap
-#endif
 #ifndef SYS_mremap
 #define SYS_mremap __NR_mremap
 #endif
 #endif  // __BIONIC__
 
-// Platform specific logic extracted from
-// https://chromium.googlesource.com/linux-syscall-support/+/master/linux_syscall_support.h
-static inline void* do_mmap64(void* start, size_t length, int prot,
-                              int flags, int fd, off64_t offset) __THROW {
-#if defined(__i386__) ||                                                \
-  defined(__ARM_ARCH_3__) || defined(__ARM_EABI__) ||                   \
-  (defined(__mips__) && _MIPS_SIM == _MIPS_SIM_ABI32) ||                \
-  (defined(__PPC__) && !defined(__PPC64__)) ||                          \
-  (defined(__s390__) && !defined(__s390x__))
-  // On these architectures, implement mmap with mmap2.
-  static int pagesize = 0;
-  if (pagesize == 0) {
-    pagesize = getpagesize();
-  }
-  if (offset < 0 || offset % pagesize != 0) {
-    errno = EINVAL;
-    return MAP_FAILED;
-  }
-#ifdef __BIONIC__
-  // SYS_mmap2 has problems on Android API level <= 16.
-  // Workaround by invoking __mmap2() instead.
-  return __mmap2(start, length, prot, flags, fd, offset / pagesize);
-#else
-  return reinterpret_cast<void*>(
-      syscall(SYS_mmap2, start, length, prot, flags, fd,
-              static_cast<off_t>(offset / pagesize)));
-#endif
-#elif defined(__s390x__)
-  // On s390x, mmap() arguments are passed in memory.
-  uint32_t buf[6] = {
-      reinterpret_cast<uint32_t>(start), static_cast<uint32_t>(length),
-      static_cast<uint32_t>(prot),       static_cast<uint32_t>(flags),
-      static_cast<uint32_t>(fd),         static_cast<uint32_t>(offset)};
-  return reintrepret_cast<void*>(syscall(SYS_mmap, buf));
-#elif defined(__x86_64__)
-  // The x32 ABI has 32 bit longs, but the syscall interface is 64 bit.
-  // We need to explicitly cast to an unsigned 64 bit type to avoid implicit
-  // sign extension.  We can't cast pointers directly because those are
-  // 32 bits, and gcc will dump ugly warnings about casting from a pointer
-  // to an integer of a different size. We also need to make sure __off64_t
-  // isn't truncated to 32-bits under x32.
-  #define MMAP_SYSCALL_ARG(x) ((uint64_t)(uintptr_t)(x))
-  return reinterpret_cast<void*>(
-      syscall(SYS_mmap, MMAP_SYSCALL_ARG(start), MMAP_SYSCALL_ARG(length),
-              MMAP_SYSCALL_ARG(prot), MMAP_SYSCALL_ARG(flags),
-              MMAP_SYSCALL_ARG(fd), static_cast<uint64_t>(offset)));
-  #undef MMAP_SYSCALL_ARG
-#else  // Remaining 64-bit aritectures.
-  static_assert(sizeof(unsigned long) == 8, "Platform is not 64-bit");
-  return reinterpret_cast<void*>(
-      syscall(SYS_mmap, start, length, prot, flags, fd, offset));
-#endif
-}
-
-// We use do_mmap64 abstraction to put MallocHook::InvokeMmapHook
-// calls right into mmap and mmap64, so that the stack frames in the caller's
-// stack are at the same offsets for all the calls of memory allocating
-// functions.
+// We put MallocHook::InvokeMmapHook calls right into mmap and mmap64, so that
+// the stack frames in the caller's stack are at the same offsets for all the
+// calls of memory allocating functions.
 
 // Put all callers of MallocHook::Invoke* in this module into
 // malloc_hook section,
@@ -148,7 +77,8 @@ extern "C" void* mmap64(void *start, size_t length, int prot, int flags,
   void *result;
   if (!absl::base_internal::MallocHook::InvokeMmapReplacement(
           start, length, prot, flags, fd, offset, &result)) {
-    result = do_mmap64(start, length, prot, flags, fd, offset);
+    result = absl::base_internal::DirectMmap(start, length, prot, flags, fd,
+                                             offset);
   }
   absl::base_internal::MallocHook::InvokeMmapHook(result, start, length, prot,
                                                   flags, fd, offset);
@@ -164,8 +94,9 @@ extern "C" void* mmap(void *start, size_t length, int prot, int flags,
   void *result;
   if (!absl::base_internal::MallocHook::InvokeMmapReplacement(
           start, length, prot, flags, fd, offset, &result)) {
-    result = do_mmap64(start, length, prot, flags, fd,
-                       static_cast<size_t>(offset)); // avoid sign extension
+    result = absl::base_internal::DirectMmap(
+        start, length, prot, flags, fd,
+        static_cast<size_t>(offset)); // avoid sign extension
   }
   absl::base_internal::MallocHook::InvokeMmapHook(result, start, length, prot,
                                                   flags, fd, offset);
@@ -179,7 +110,7 @@ extern "C" int munmap(void* start, size_t length) __THROW {
   int result;
   if (!absl::base_internal::MallocHook::InvokeMunmapReplacement(start, length,
                                                                 &result)) {
-    result = syscall(SYS_munmap, start, length);
+    result = absl::base_internal::DirectMunmap(start, length);
   }
   return result;
 }
@@ -219,7 +150,8 @@ namespace base_internal {
   void* result;
   if (!MallocHook::InvokeMmapReplacement(
           start, length, prot, flags, fd, offset, &result)) {
-    result = do_mmap64(start, length, prot, flags, fd, offset);
+    result = absl::base_internal::DirectMmap(start, length, prot, flags, fd,
+                                             offset);
   }
   return result;
 }
@@ -227,7 +159,7 @@ namespace base_internal {
 /*static*/int MallocHook::UnhookedMUnmap(void *start, size_t length) {
   int result;
   if (!MallocHook::InvokeMunmapReplacement(start, length, &result)) {
-    result = syscall(SYS_munmap, start, length);
+    result = absl::base_internal::DirectMunmap(start, length);
   }
   return result;
 }