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8feba8d584
This PR replaces our use of `__dso_handle` and (indirectly) `dladdr()` when figuring out the base address of loaded Swift images on ELF-based platforms. Instead, we use `__ehdr_start` which refers to the start of the image's ELF header (i.e. the start of the file) and is provided by the compiler/linker for this purpose. This pointer is consumed by `swift_addNewDSOImage()` and, later, by Swift Testing when running tests, but is otherwise unused, so the less work we do on it at runtime, the better. A fallback path is present that, for images that do not contain `__ehdr_start`, derives the address by calling `dladdr()` on the section structure's address. Resolves #84997.
101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
//===--- MetadataSections.h -----------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// This file contains the declaration of the MetadataSectionsRange and
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/// MetadataSections struct, which represent, respectively, information about
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/// an image's section, and an image's metadata information (which is composed
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/// of multiple section information).
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///
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_STDLIB_SHIMS_METADATASECTIONS_H
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#define SWIFT_STDLIB_SHIMS_METADATASECTIONS_H
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#if defined(__cplusplus) && !defined(__swift__)
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#include <atomic>
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#endif
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#include "SwiftStddef.h"
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#include "SwiftStdint.h"
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#ifdef __cplusplus
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namespace swift {
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extern "C" {
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#endif
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/// Specifies the address range corresponding to a section.
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typedef struct MetadataSectionRange {
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__swift_uintptr_t start;
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__swift_size_t length;
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} MetadataSectionRange;
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/// Identifies the address space ranges for the Swift metadata required by the
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/// Swift runtime.
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///
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/// \warning If you change the size of this structure by adding fields, it is an
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/// ABI-breaking change on platforms that use it. Make sure to increment
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/// \c CurrentSectionMetadataVersion if you do. To minimize impact, always add
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/// new fields to the \em end of the structure.
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struct MetadataSections {
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__swift_uintptr_t version;
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/// The base address of the image where this metadata section was defined, as
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/// reported when the section was registered with the Swift runtime.
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///
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/// The value of this field is equivalent to the value of
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/// \c SymbolInfo::baseAddress as returned from \c SymbolInfo::lookup() for a
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/// symbol in the image that contains these sections.
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///
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/// For Mach-O images, set this field to \c __dso_handle (i.e. the Mach header
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/// for the image.) For ELF images, set it to \c __ehdr_start. For COFF
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/// images, set this field to \c __ImageBase.
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///
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/// For platforms that have a single statically-linked image or no dynamic
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/// loader (i.e. no equivalent of \c __dso_handle, \c __ehdr_start, or
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/// \c __ImageBase), this field is ignored and should be set to \c nullptr.
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///
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/// \sa swift_addNewDSOImage()
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const void *baseAddress;
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/// Unused.
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///
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/// These pointers (or the space they occupy) can be repurposed without
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/// causing ABI breakage. Set them to \c nullptr.
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void *unused0;
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void *unused1;
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MetadataSectionRange swift5_protocols;
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MetadataSectionRange swift5_protocol_conformances;
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MetadataSectionRange swift5_type_metadata;
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MetadataSectionRange swift5_typeref;
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MetadataSectionRange swift5_reflstr;
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MetadataSectionRange swift5_fieldmd;
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MetadataSectionRange swift5_assocty;
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MetadataSectionRange swift5_replace;
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MetadataSectionRange swift5_replac2;
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MetadataSectionRange swift5_builtin;
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MetadataSectionRange swift5_capture;
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MetadataSectionRange swift5_mpenum;
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MetadataSectionRange swift5_accessible_functions;
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MetadataSectionRange swift5_runtime_attributes;
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MetadataSectionRange swift5_tests;
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};
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#ifdef __cplusplus
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} //extern "C"
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} // namespace swift
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#endif
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#endif // SWIFT_STDLIB_SHIMS_METADATASECTIONS_H
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