diff options
Diffstat (limited to 'toolkit/crashreporter/google-breakpad/src/common/dwarf/cfi_assembler.h')
-rw-r--r-- | toolkit/crashreporter/google-breakpad/src/common/dwarf/cfi_assembler.h | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/toolkit/crashreporter/google-breakpad/src/common/dwarf/cfi_assembler.h b/toolkit/crashreporter/google-breakpad/src/common/dwarf/cfi_assembler.h new file mode 100644 index 000000000..227812b58 --- /dev/null +++ b/toolkit/crashreporter/google-breakpad/src/common/dwarf/cfi_assembler.h @@ -0,0 +1,269 @@ +// -*- mode: C++ -*- + +// Copyright (c) 2010, Google Inc. +// 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. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// 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. + +// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com> + +// cfi_assembler.h: Define CFISection, a class for creating properly +// (and improperly) formatted DWARF CFI data for unit tests. + +#ifndef PROCESSOR_CFI_ASSEMBLER_H_ +#define PROCESSOR_CFI_ASSEMBLER_H_ + +#include <string> + +#include "common/dwarf/dwarf2enums.h" +#include "common/test_assembler.h" +#include "common/using_std_string.h" +#include "google_breakpad/common/breakpad_types.h" + +namespace google_breakpad { + +using dwarf2reader::DwarfPointerEncoding; +using google_breakpad::test_assembler::Endianness; +using google_breakpad::test_assembler::Label; +using google_breakpad::test_assembler::Section; + +class CFISection: public Section { + public: + + // CFI augmentation strings beginning with 'z', defined by the + // Linux/IA-64 C++ ABI, can specify interesting encodings for + // addresses appearing in FDE headers and call frame instructions (and + // for additional fields whose presence the augmentation string + // specifies). In particular, pointers can be specified to be relative + // to various base address: the start of the .text section, the + // location holding the address itself, and so on. These allow the + // frame data to be position-independent even when they live in + // write-protected pages. These variants are specified at the + // following two URLs: + // + // http://refspecs.linux-foundation.org/LSB_4.0.0/LSB-Core-generic/LSB-Core-generic/dwarfext.html + // http://refspecs.linux-foundation.org/LSB_4.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html + // + // CFISection leaves the production of well-formed 'z'-augmented CIEs and + // FDEs to the user, but does provide EncodedPointer, to emit + // properly-encoded addresses for a given pointer encoding. + // EncodedPointer uses an instance of this structure to find the base + // addresses it should use; you can establish a default for all encoded + // pointers appended to this section with SetEncodedPointerBases. + struct EncodedPointerBases { + EncodedPointerBases() : cfi(), text(), data() { } + + // The starting address of this CFI section in memory, for + // DW_EH_PE_pcrel. DW_EH_PE_pcrel pointers may only be used in data + // that has is loaded into the program's address space. + uint64_t cfi; + + // The starting address of this file's .text section, for DW_EH_PE_textrel. + uint64_t text; + + // The starting address of this file's .got or .eh_frame_hdr section, + // for DW_EH_PE_datarel. + uint64_t data; + }; + + // Create a CFISection whose endianness is ENDIANNESS, and where + // machine addresses are ADDRESS_SIZE bytes long. If EH_FRAME is + // true, use the .eh_frame format, as described by the Linux + // Standards Base Core Specification, instead of the DWARF CFI + // format. + CFISection(Endianness endianness, size_t address_size, + bool eh_frame = false) + : Section(endianness), address_size_(address_size), eh_frame_(eh_frame), + pointer_encoding_(dwarf2reader::DW_EH_PE_absptr), + encoded_pointer_bases_(), entry_length_(NULL), in_fde_(false) { + // The 'start', 'Here', and 'Mark' members of a CFISection all refer + // to section offsets. + start() = 0; + } + + // Return this CFISection's address size. + size_t AddressSize() const { return address_size_; } + + // Return true if this CFISection uses the .eh_frame format, or + // false if it contains ordinary DWARF CFI data. + bool ContainsEHFrame() const { return eh_frame_; } + + // Use ENCODING for pointers in calls to FDEHeader and EncodedPointer. + void SetPointerEncoding(DwarfPointerEncoding encoding) { + pointer_encoding_ = encoding; + } + + // Use the addresses in BASES as the base addresses for encoded + // pointers in subsequent calls to FDEHeader or EncodedPointer. + // This function makes a copy of BASES. + void SetEncodedPointerBases(const EncodedPointerBases &bases) { + encoded_pointer_bases_ = bases; + } + + // Append a Common Information Entry header to this section with the + // given values. If dwarf64 is true, use the 64-bit DWARF initial + // length format for the CIE's initial length. Return a reference to + // this section. You should call FinishEntry after writing the last + // instruction for the CIE. + // + // Before calling this function, you will typically want to use Mark + // or Here to make a label to pass to FDEHeader that refers to this + // CIE's position in the section. + CFISection &CIEHeader(uint64_t code_alignment_factor, + int data_alignment_factor, + unsigned return_address_register, + uint8_t version = 3, + const string &augmentation = "", + bool dwarf64 = false); + + // Append a Frame Description Entry header to this section with the + // given values. If dwarf64 is true, use the 64-bit DWARF initial + // length format for the CIE's initial length. Return a reference to + // this section. You should call FinishEntry after writing the last + // instruction for the CIE. + // + // This function doesn't support entries that are longer than + // 0xffffff00 bytes. (The "initial length" is always a 32-bit + // value.) Nor does it support .debug_frame sections longer than + // 0xffffff00 bytes. + CFISection &FDEHeader(Label cie_pointer, + uint64_t initial_location, + uint64_t address_range, + bool dwarf64 = false); + + // Note the current position as the end of the last CIE or FDE we + // started, after padding with DW_CFA_nops for alignment. This + // defines the label representing the entry's length, cited in the + // entry's header. Return a reference to this section. + CFISection &FinishEntry(); + + // Append the contents of BLOCK as a DW_FORM_block value: an + // unsigned LEB128 length, followed by that many bytes of data. + CFISection &Block(const string &block) { + ULEB128(block.size()); + Append(block); + return *this; + } + + // Append ADDRESS to this section, in the appropriate size and + // endianness. Return a reference to this section. + CFISection &Address(uint64_t address) { + Section::Append(endianness(), address_size_, address); + return *this; + } + CFISection &Address(Label address) { + Section::Append(endianness(), address_size_, address); + return *this; + } + + // Append ADDRESS to this section, using ENCODING and BASES. ENCODING + // defaults to this section's default encoding, established by + // SetPointerEncoding. BASES defaults to this section's bases, set by + // SetEncodedPointerBases. If the DW_EH_PE_indirect bit is set in the + // encoding, assume that ADDRESS is where the true address is stored. + // Return a reference to this section. + // + // (C++ doesn't let me use default arguments here, because I want to + // refer to members of *this in the default argument expression.) + CFISection &EncodedPointer(uint64_t address) { + return EncodedPointer(address, pointer_encoding_, encoded_pointer_bases_); + } + CFISection &EncodedPointer(uint64_t address, DwarfPointerEncoding encoding) { + return EncodedPointer(address, encoding, encoded_pointer_bases_); + } + CFISection &EncodedPointer(uint64_t address, DwarfPointerEncoding encoding, + const EncodedPointerBases &bases); + + // Restate some member functions, to keep chaining working nicely. + CFISection &Mark(Label *label) { Section::Mark(label); return *this; } + CFISection &D8(uint8_t v) { Section::D8(v); return *this; } + CFISection &D16(uint16_t v) { Section::D16(v); return *this; } + CFISection &D16(Label v) { Section::D16(v); return *this; } + CFISection &D32(uint32_t v) { Section::D32(v); return *this; } + CFISection &D32(const Label &v) { Section::D32(v); return *this; } + CFISection &D64(uint64_t v) { Section::D64(v); return *this; } + CFISection &D64(const Label &v) { Section::D64(v); return *this; } + CFISection &LEB128(long long v) { Section::LEB128(v); return *this; } + CFISection &ULEB128(uint64_t v) { Section::ULEB128(v); return *this; } + + private: + // A length value that we've appended to the section, but is not yet + // known. LENGTH is the appended value; START is a label referring + // to the start of the data whose length was cited. + struct PendingLength { + Label length; + Label start; + }; + + // Constants used in CFI/.eh_frame data: + + // If the first four bytes of an "initial length" are this constant, then + // the data uses the 64-bit DWARF format, and the length itself is the + // subsequent eight bytes. + static const uint32_t kDwarf64InitialLengthMarker = 0xffffffffU; + + // The CIE identifier for 32- and 64-bit DWARF CFI and .eh_frame data. + static const uint32_t kDwarf32CIEIdentifier = ~(uint32_t)0; + static const uint64_t kDwarf64CIEIdentifier = ~(uint64_t)0; + static const uint32_t kEHFrame32CIEIdentifier = 0; + static const uint64_t kEHFrame64CIEIdentifier = 0; + + // The size of a machine address for the data in this section. + size_t address_size_; + + // If true, we are generating a Linux .eh_frame section, instead of + // a standard DWARF .debug_frame section. + bool eh_frame_; + + // The encoding to use for FDE pointers. + DwarfPointerEncoding pointer_encoding_; + + // The base addresses to use when emitting encoded pointers. + EncodedPointerBases encoded_pointer_bases_; + + // The length value for the current entry. + // + // Oddly, this must be dynamically allocated. Labels never get new + // values; they only acquire constraints on the value they already + // have, or assert if you assign them something incompatible. So + // each header needs truly fresh Label objects to cite in their + // headers and track their positions. The alternative is explicit + // destructor invocation and a placement new. Ick. + PendingLength *entry_length_; + + // True if we are currently emitting an FDE --- that is, we have + // called FDEHeader but have not yet called FinishEntry. + bool in_fde_; + + // If in_fde_ is true, this is its starting address. We use this for + // emitting DW_EH_PE_funcrel pointers. + uint64_t fde_start_address_; +}; + +} // namespace google_breakpad + +#endif // PROCESSOR_CFI_ASSEMBLER_H_ |