michael@0: // Copyright (c) 2010, Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
michael@0: 
michael@0: // cfi_assembler.cc: Implementation of google_breakpad::CFISection class.
michael@0: // See cfi_assembler.h for details.
michael@0: 
michael@0: #include "common/dwarf/cfi_assembler.h"
michael@0: 
michael@0: #include <assert.h>
michael@0: #include <stdlib.h>
michael@0: 
michael@0: namespace google_breakpad {
michael@0: 
michael@0: using dwarf2reader::DwarfPointerEncoding;
michael@0:   
michael@0: CFISection &CFISection::CIEHeader(uint64_t code_alignment_factor,
michael@0:                                   int data_alignment_factor,
michael@0:                                   unsigned return_address_register,
michael@0:                                   uint8_t version,
michael@0:                                   const string &augmentation,
michael@0:                                   bool dwarf64) {
michael@0:   assert(!entry_length_);
michael@0:   entry_length_ = new PendingLength();
michael@0:   in_fde_ = false;
michael@0: 
michael@0:   if (dwarf64) {
michael@0:     D32(kDwarf64InitialLengthMarker);
michael@0:     D64(entry_length_->length);
michael@0:     entry_length_->start = Here();
michael@0:     D64(eh_frame_ ? kEHFrame64CIEIdentifier : kDwarf64CIEIdentifier);
michael@0:   } else {
michael@0:     D32(entry_length_->length);
michael@0:     entry_length_->start = Here();
michael@0:     D32(eh_frame_ ? kEHFrame32CIEIdentifier : kDwarf32CIEIdentifier);
michael@0:   }
michael@0:   D8(version);
michael@0:   AppendCString(augmentation);
michael@0:   ULEB128(code_alignment_factor);
michael@0:   LEB128(data_alignment_factor);
michael@0:   if (version == 1)
michael@0:     D8(return_address_register);
michael@0:   else
michael@0:     ULEB128(return_address_register);
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: CFISection &CFISection::FDEHeader(Label cie_pointer,
michael@0:                                   uint64_t initial_location,
michael@0:                                   uint64_t address_range,
michael@0:                                   bool dwarf64) {
michael@0:   assert(!entry_length_);
michael@0:   entry_length_ = new PendingLength();
michael@0:   in_fde_ = true;
michael@0:   fde_start_address_ = initial_location;
michael@0: 
michael@0:   if (dwarf64) {
michael@0:     D32(0xffffffff);
michael@0:     D64(entry_length_->length);
michael@0:     entry_length_->start = Here();
michael@0:     if (eh_frame_)
michael@0:       D64(Here() - cie_pointer);
michael@0:     else
michael@0:       D64(cie_pointer);
michael@0:   } else {
michael@0:     D32(entry_length_->length);
michael@0:     entry_length_->start = Here();
michael@0:     if (eh_frame_)
michael@0:       D32(Here() - cie_pointer);
michael@0:     else
michael@0:       D32(cie_pointer);
michael@0:   }
michael@0:   EncodedPointer(initial_location);
michael@0:   // The FDE length in an .eh_frame section uses the same encoding as the
michael@0:   // initial location, but ignores the base address (selected by the upper
michael@0:   // nybble of the encoding), as it's a length, not an address that can be
michael@0:   // made relative.
michael@0:   EncodedPointer(address_range,
michael@0:                  DwarfPointerEncoding(pointer_encoding_ & 0x0f));
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: CFISection &CFISection::FinishEntry() {
michael@0:   assert(entry_length_);
michael@0:   Align(address_size_, dwarf2reader::DW_CFA_nop);
michael@0:   entry_length_->length = Here() - entry_length_->start;
michael@0:   delete entry_length_;
michael@0:   entry_length_ = NULL;
michael@0:   in_fde_ = false;
michael@0:   return *this;
michael@0: }
michael@0: 
michael@0: CFISection &CFISection::EncodedPointer(uint64_t address,
michael@0:                                        DwarfPointerEncoding encoding,
michael@0:                                        const EncodedPointerBases &bases) {
michael@0:   // Omitted data is extremely easy to emit.
michael@0:   if (encoding == dwarf2reader::DW_EH_PE_omit)
michael@0:     return *this;
michael@0: 
michael@0:   // If (encoding & dwarf2reader::DW_EH_PE_indirect) != 0, then we assume
michael@0:   // that ADDRESS is the address at which the pointer is stored --- in
michael@0:   // other words, that bit has no effect on how we write the pointer.
michael@0:   encoding = DwarfPointerEncoding(encoding & ~dwarf2reader::DW_EH_PE_indirect);
michael@0: 
michael@0:   // Find the base address to which this pointer is relative. The upper
michael@0:   // nybble of the encoding specifies this.
michael@0:   uint64_t base;
michael@0:   switch (encoding & 0xf0) {
michael@0:     case dwarf2reader::DW_EH_PE_absptr:  base = 0;                  break;
michael@0:     case dwarf2reader::DW_EH_PE_pcrel:   base = bases.cfi + Size(); break;
michael@0:     case dwarf2reader::DW_EH_PE_textrel: base = bases.text;         break;
michael@0:     case dwarf2reader::DW_EH_PE_datarel: base = bases.data;         break;
michael@0:     case dwarf2reader::DW_EH_PE_funcrel: base = fde_start_address_; break;
michael@0:     case dwarf2reader::DW_EH_PE_aligned: base = 0;                  break;
michael@0:     default: abort();
michael@0:   };
michael@0: 
michael@0:   // Make ADDRESS relative. Yes, this is appropriate even for "absptr"
michael@0:   // values; see gcc/unwind-pe.h.
michael@0:   address -= base;
michael@0: 
michael@0:   // Align the pointer, if required.
michael@0:   if ((encoding & 0xf0) == dwarf2reader::DW_EH_PE_aligned)
michael@0:     Align(AddressSize());
michael@0: 
michael@0:   // Append ADDRESS to this section in the appropriate form. For the
michael@0:   // fixed-width forms, we don't need to differentiate between signed and
michael@0:   // unsigned encodings, because ADDRESS has already been extended to 64
michael@0:   // bits before it was passed to us.
michael@0:   switch (encoding & 0x0f) {
michael@0:     case dwarf2reader::DW_EH_PE_absptr:
michael@0:       Address(address);
michael@0:       break;
michael@0: 
michael@0:     case dwarf2reader::DW_EH_PE_uleb128:
michael@0:       ULEB128(address);
michael@0:       break;
michael@0: 
michael@0:     case dwarf2reader::DW_EH_PE_sleb128:
michael@0:       LEB128(address);
michael@0:       break;
michael@0: 
michael@0:     case dwarf2reader::DW_EH_PE_udata2:
michael@0:     case dwarf2reader::DW_EH_PE_sdata2:
michael@0:       D16(address);
michael@0:       break;
michael@0: 
michael@0:     case dwarf2reader::DW_EH_PE_udata4:
michael@0:     case dwarf2reader::DW_EH_PE_sdata4:
michael@0:       D32(address);
michael@0:       break;
michael@0: 
michael@0:     case dwarf2reader::DW_EH_PE_udata8:
michael@0:     case dwarf2reader::DW_EH_PE_sdata8:
michael@0:       D64(address);
michael@0:       break;
michael@0: 
michael@0:     default:
michael@0:       abort();
michael@0:   }
michael@0: 
michael@0:   return *this;
michael@0: };
michael@0: 
michael@0: const uint32_t CFISection::kDwarf64InitialLengthMarker;
michael@0: const uint32_t CFISection::kDwarf32CIEIdentifier;
michael@0: const uint64_t CFISection::kDwarf64CIEIdentifier;
michael@0: const uint32_t CFISection::kEHFrame32CIEIdentifier;
michael@0: const uint64_t CFISection::kEHFrame64CIEIdentifier;
michael@0: 
michael@0: } // namespace google_breakpad