[runtime] ELF DSO binary section fixes

- Rename swift::addNewDSOImage() to swift_addNewDSOImage() and
  export using SWIFT_RUNTIME_EXPORT.

- Move ELF specific parts of ImageInspection.h into
  ImageInspectionELF.h.

Author: spevans

stdlib/public/runtime/CMakeLists.txt

@@ -18,6 +18,8 @@ if(SWIFT_RUNTIME_ENABLE_LEAK_CHECKER)
   set(swift_runtime_leaks_sources Leaks.mm)
 endif()
 
+set(section_magic_compile_flags ${swift_runtime_compile_flags})
+
 list(APPEND swift_runtime_compile_flags
      "-D__SWIFT_CURRENT_DYLIB=swiftCore")
 
@@ -132,19 +134,19 @@ endforeach()
 
 add_swift_library(section_magic_loader OBJECT_LIBRARY IS_STDLIB IS_STDLIB_CORE
     ImageInspectionInit.cpp
-    C_COMPILE_FLAGS ${swift_runtime_compile_flags}
+    C_COMPILE_FLAGS ${section_magic_compile_flags}
     TARGET_SDKS "${ELFISH_SDKS}"
     LINK_FLAGS ${swift_runtime_linker_flags}
     INSTALL_IN_COMPONENT never_install)
 add_swift_library(section_magic_begin OBJECT_LIBRARY IS_STDLIB IS_STDLIB_CORE
     swift_sections.S
-    C_COMPILE_FLAGS ${swift_runtime_compile_flags} "-DSWIFT_BEGIN"
+    C_COMPILE_FLAGS ${section_magic_compile_flags} "-DSWIFT_BEGIN"
     TARGET_SDKS "${ELFISH_SDKS}"
     LINK_FLAGS ${swift_runtime_linker_flags}
     INSTALL_IN_COMPONENT never_install)
 add_swift_library(section_magic_end OBJECT_LIBRARY IS_STDLIB IS_STDLIB_CORE
     swift_sections.S
-    C_COMPILE_FLAGS ${swift_runtime_compile_flags} "-DSWIFT_END"
+    C_COMPILE_FLAGS ${section_magic_compile_flags} "-DSWIFT_END"
     LINK_FLAGS ${swift_runtime_linker_flags}
     TARGET_SDKS "${ELFISH_SDKS}"
     INSTALL_IN_COMPONENT never_install)

stdlib/public/runtime/ImageInspection.h

@@ -19,6 +19,7 @@
 #ifndef SWIFT_RUNTIME_IMAGE_INSPECTION_H
 #define SWIFT_RUNTIME_IMAGE_INSPECTION_H
 
+#include "ImageInspectionELF.h"
 #include <cstdint>
 
 namespace swift {
@@ -30,18 +31,6 @@ namespace swift {
     void *symbolAddress;
   };
 
-#if defined(__ELF__) || defined(__ANDROID__)
-
-struct SectionInfo {
-  uint64_t size;
-  const char *data;
-};
-
-// Called by injected constructors when a dynamic library is loaded.
-void addNewDSOImage(const void *addr);
-
-#endif // defined(__ELF__) || defined(__ANDROID__)
-
 /// Load the metadata from the image necessary to find a type's
 /// protocol conformance.
 void initializeProtocolConformanceLookup();

stdlib/public/runtime/ImageInspectionELF.cpp

@@ -19,11 +19,9 @@
 #if defined(__ELF__) || defined(__ANDROID__)
 
 #include "ImageInspection.h"
-#include "../SwiftShims/Visibility.h"
-#include <atomic>
+#include <dlfcn.h>
 #include <elf.h>
 #include <link.h>
-#include <dlfcn.h>
 #include <string.h>
 
 using namespace swift;
@@ -37,29 +35,26 @@ static const char ProtocolConformancesSymbol[] =
 static const char TypeMetadataRecordsSymbol[] =
   ".swift2_type_metadata_start";
 
-static std::atomic<bool> didInitializeProtocolConformanceLookup;
-static std::atomic<bool> didInitializeTypeMetadataLookup;
-
 /// Context arguments passed down from dl_iterate_phdr to its callback.
 struct InspectArgs {
   /// Symbol name to look up.
   const char *symbolName;
   /// Callback function to invoke with the metadata block.
   void (*addBlock)(const void *start, uintptr_t size);
   /// Set to true when initialize*Lookup() is called.
-  std::atomic<bool> *didInitializeLookup;
+  bool didInitializeLookup;
 };
 
 static InspectArgs ProtocolConformanceArgs = {
   ProtocolConformancesSymbol,
   addImageProtocolConformanceBlockCallback,
-  &didInitializeProtocolConformanceLookup
+  false
 };
 
 static InspectArgs TypeMetadataRecordArgs = {
   TypeMetadataRecordsSymbol,
   addImageTypeMetadataRecordBlockCallback,
-  &didInitializeTypeMetadataLookup
+  false
 };
 
 
@@ -84,15 +79,15 @@ static SectionInfo getSectionInfo(const char *imageName,
 
 static int iteratePHDRCallback(struct dl_phdr_info *info,
                                size_t size, void *data) {
-  const InspectArgs *inspectArgs = reinterpret_cast<const InspectArgs *>(data);
+  InspectArgs *inspectArgs = reinterpret_cast<InspectArgs *>(data);
   const char *fname = info->dlpi_name;
 
   // While dl_iterate_phdr() is in progress it holds a lock to prevent other
   // images being loaded. The initialize flag is set here inside the callback so
   // that addNewDSOImage() sees a consistent state. If it was set outside the
   // dl_interate_phdr() call then it could result in images being missed or
   // added twice.
-  inspectArgs->didInitializeLookup->store(true, std::memory_order_release);
+  inspectArgs->didInitializeLookup = true;
 
   if (fname == nullptr || fname[0] == '\0') {
     // The filename may be null for both the dynamic loader and main executable.
@@ -147,12 +142,12 @@ void swift::initializeTypeMetadataRecordLookup() {
 // dladdr() to dlopen() the image after the appropiate initialize*Lookup()
 // function has been called.
 SWIFT_RUNTIME_EXPORT
-void swift::addNewDSOImage(const void *addr) {
-  if (didInitializeProtocolConformanceLookup.load(std::memory_order_acquire)) {
+void swift_addNewDSOImage(const void *addr) {
+  if (ProtocolConformanceArgs.didInitializeLookup) {
     addBlockInImage(&ProtocolConformanceArgs, addr);
   }
 
-  if (didInitializeTypeMetadataLookup.load(std::memory_order_acquire)) {
+  if (TypeMetadataRecordArgs.didInitializeLookup) {
     addBlockInImage(&TypeMetadataRecordArgs, addr);
   }
 }

stdlib/public/runtime/ImageInspectionELF.h

@@ -0,0 +1,38 @@
+//===--- ImageInspectionELF.h ---------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// ELF specific image inspection routines.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_RUNTIME_IMAGE_INSPECTION_ELF_H
+#define SWIFT_RUNTIME_IMAGE_INSPECTION_ELF_H
+
+#if defined(__ELF__) || defined(__ANDROID__)
+
+#include "../SwiftShims/Visibility.h"
+#include <cstdint>
+
+namespace swift {
+  struct SectionInfo {
+    uint64_t size;
+    const char *data;
+  };
+}
+
+// Called by injected constructors when a dynamic library is loaded.
+SWIFT_RUNTIME_EXPORT
+void swift_addNewDSOImage(const void *addr);
+
+#endif // defined(__ELF__) || defined(__ANDROID__)
+
+#endif // SWIFT_RUNTIME_IMAGE_INSPECTION_ELF_H

stdlib/public/runtime/ImageInspectionInit.cpp

@@ -20,13 +20,12 @@
 #include "ImageInspection.h"
 #include <memory>
 
-using namespace swift;
-
 // This is called at startup and by each shared object as it is dlopen()'d to
 // allow the section data for the object to be loaded.
 __attribute__((constructor))
 static void sectionDataInit() {
-  addNewDSOImage(reinterpret_cast<void *>(std::addressof(sectionDataInit)));
+  void *addr = reinterpret_cast<void *>(std::addressof(sectionDataInit));
+  swift_addNewDSOImage(addr);
 }
 
 #endif