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// 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.cc: Implementation of google_breakpad::CFISection class.
// See cfi_assembler.h for details.
#include "common/dwarf/cfi_assembler.h"
#include <assert.h>
#include <stdlib.h>
namespace google_breakpad {
using dwarf2reader::DwarfPointerEncoding;
CFISection &CFISection::CIEHeader(uint64_t code_alignment_factor,
int data_alignment_factor,
unsigned return_address_register,
uint8_t version,
const string &augmentation,
bool dwarf64,
uint8_t address_size,
uint8_t segment_size) {
assert(!entry_length_);
entry_length_ = new PendingLength();
in_fde_ = false;
if (dwarf64) {
D32(kDwarf64InitialLengthMarker);
D64(entry_length_->length);
entry_length_->start = Here();
D64(eh_frame_ ? kEHFrame64CIEIdentifier : kDwarf64CIEIdentifier);
} else {
D32(entry_length_->length);
entry_length_->start = Here();
D32(eh_frame_ ? kEHFrame32CIEIdentifier : kDwarf32CIEIdentifier);
}
D8(version);
AppendCString(augmentation);
if (version >= 4) {
D8(address_size);
D8(segment_size);
}
ULEB128(code_alignment_factor);
LEB128(data_alignment_factor);
if (version == 1)
D8(return_address_register);
else
ULEB128(return_address_register);
return *this;
}
CFISection &CFISection::FDEHeader(Label cie_pointer,
uint64_t initial_location,
uint64_t address_range,
bool dwarf64) {
assert(!entry_length_);
entry_length_ = new PendingLength();
in_fde_ = true;
fde_start_address_ = initial_location;
if (dwarf64) {
D32(0xffffffff);
D64(entry_length_->length);
entry_length_->start = Here();
if (eh_frame_)
D64(Here() - cie_pointer);
else
D64(cie_pointer);
} else {
D32(entry_length_->length);
entry_length_->start = Here();
if (eh_frame_)
D32(Here() - cie_pointer);
else
D32(cie_pointer);
}
EncodedPointer(initial_location);
// The FDE length in an .eh_frame section uses the same encoding as the
// initial location, but ignores the base address (selected by the upper
// nybble of the encoding), as it's a length, not an address that can be
// made relative.
EncodedPointer(address_range,
DwarfPointerEncoding(pointer_encoding_ & 0x0f));
return *this;
}
CFISection &CFISection::FinishEntry() {
assert(entry_length_);
Align(address_size_, dwarf2reader::DW_CFA_nop);
entry_length_->length = Here() - entry_length_->start;
delete entry_length_;
entry_length_ = NULL;
in_fde_ = false;
return *this;
}
CFISection &CFISection::EncodedPointer(uint64_t address,
DwarfPointerEncoding encoding,
const EncodedPointerBases &bases) {
// Omitted data is extremely easy to emit.
if (encoding == dwarf2reader::DW_EH_PE_omit)
return *this;
// If (encoding & dwarf2reader::DW_EH_PE_indirect) != 0, then we assume
// that ADDRESS is the address at which the pointer is stored --- in
// other words, that bit has no effect on how we write the pointer.
encoding = DwarfPointerEncoding(encoding & ~dwarf2reader::DW_EH_PE_indirect);
// Find the base address to which this pointer is relative. The upper
// nybble of the encoding specifies this.
uint64_t base;
switch (encoding & 0xf0) {
case dwarf2reader::DW_EH_PE_absptr: base = 0; break;
case dwarf2reader::DW_EH_PE_pcrel: base = bases.cfi + Size(); break;
case dwarf2reader::DW_EH_PE_textrel: base = bases.text; break;
case dwarf2reader::DW_EH_PE_datarel: base = bases.data; break;
case dwarf2reader::DW_EH_PE_funcrel: base = fde_start_address_; break;
case dwarf2reader::DW_EH_PE_aligned: base = 0; break;
default: abort();
};
// Make ADDRESS relative. Yes, this is appropriate even for "absptr"
// values; see gcc/unwind-pe.h.
address -= base;
// Align the pointer, if required.
if ((encoding & 0xf0) == dwarf2reader::DW_EH_PE_aligned)
Align(AddressSize());
// Append ADDRESS to this section in the appropriate form. For the
// fixed-width forms, we don't need to differentiate between signed and
// unsigned encodings, because ADDRESS has already been extended to 64
// bits before it was passed to us.
switch (encoding & 0x0f) {
case dwarf2reader::DW_EH_PE_absptr:
Address(address);
break;
case dwarf2reader::DW_EH_PE_uleb128:
ULEB128(address);
break;
case dwarf2reader::DW_EH_PE_sleb128:
LEB128(address);
break;
case dwarf2reader::DW_EH_PE_udata2:
case dwarf2reader::DW_EH_PE_sdata2:
D16(address);
break;
case dwarf2reader::DW_EH_PE_udata4:
case dwarf2reader::DW_EH_PE_sdata4:
D32(address);
break;
case dwarf2reader::DW_EH_PE_udata8:
case dwarf2reader::DW_EH_PE_sdata8:
D64(address);
break;
default:
abort();
}
return *this;
};
const uint32_t CFISection::kDwarf64InitialLengthMarker;
const uint32_t CFISection::kDwarf32CIEIdentifier;
const uint64_t CFISection::kDwarf64CIEIdentifier;
const uint32_t CFISection::kEHFrame32CIEIdentifier;
const uint64_t CFISection::kEHFrame64CIEIdentifier;
} // namespace google_breakpad
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