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//===-- CompactUnwindInfo.h -------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef liblldb_CompactUnwindInfo_h_
#define liblldb_CompactUnwindInfo_h_
#include <vector>
#include "lldb/Core/DataExtractor.h"
#include "lldb/Core/RangeMap.h"
#include "lldb/Host/Mutex.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/lldb-private.h"
namespace lldb_private {
// Compact Unwind info is an unwind format used on Darwin. The unwind instructions
// for typical compiler-generated functions can be expressed in a 32-bit encoding.
// The format includes a two-level index so the unwind information for a function
// can be found by two binary searches in the section. It can represent both
// stack frames that use a frame-pointer register and frameless functions, on
// i386/x86_64 for instance. When a function is too complex to be represented in
// the compact unwind format, it calls out to eh_frame unwind instructions.
// On Mac OS X / iOS, a function will have either a compact unwind representation
// or an eh_frame representation. If lldb is going to benefit from the compiler's
// description about saved register locations, it must be able to read both
// sources of information.
class CompactUnwindInfo
{
public:
CompactUnwindInfo (ObjectFile& objfile,
lldb::SectionSP& section);
~CompactUnwindInfo();
bool
GetUnwindPlan (Target &target, Address addr, UnwindPlan& unwind_plan);
bool
IsValid (const lldb::ProcessSP &process_sp);
private:
// The top level index entries of the compact unwind info
// (internal representation of struct unwind_info_section_header_index_entry)
// There are relatively few of these (one per 500/1000 functions, depending on format) so
// creating them on first scan will not be too costly.
struct UnwindIndex
{
uint32_t function_offset; // The offset of the first function covered by this index
uint32_t second_level; // The offset (inside unwind_info sect) to the second level page for this index
// (either UNWIND_SECOND_LEVEL_REGULAR or UNWIND_SECOND_LEVEL_COMPRESSED)
uint32_t lsda_array_start;// The offset (inside unwind_info sect) LSDA array for this index
uint32_t lsda_array_end; // The offset to the LSDA array for the NEXT index
bool sentinal_entry; // There is an empty index at the end which provides the upper bound of
// function addresses that are described
UnwindIndex() :
function_offset (0),
second_level (0),
lsda_array_start(0),
lsda_array_end(0),
sentinal_entry (false)
{ }
bool
operator< (const CompactUnwindInfo::UnwindIndex& rhs) const
{
return function_offset < rhs.function_offset;
}
bool
operator== (const CompactUnwindInfo::UnwindIndex& rhs) const
{
return function_offset == rhs.function_offset;
}
};
// An internal object used to store the information we retrieve about a function --
// the encoding bits and possibly the LSDA/personality function.
struct FunctionInfo
{
uint32_t encoding; // compact encoding 32-bit value for this function
Address lsda_address; // the address of the LSDA data for this function
Address personality_ptr_address; // the address where the personality routine addr can be found
uint32_t valid_range_offset_start; // first offset that this encoding is valid for (start of the function)
uint32_t valid_range_offset_end; // the offset of the start of the next function
FunctionInfo () : encoding(0), lsda_address(), personality_ptr_address(), valid_range_offset_start(0), valid_range_offset_end(0) { }
};
struct UnwindHeader
{
uint32_t version;
uint32_t common_encodings_array_offset;
uint32_t common_encodings_array_count;
uint32_t personality_array_offset;
uint32_t personality_array_count;
UnwindHeader () : common_encodings_array_offset (0), common_encodings_array_count (0), personality_array_offset (0), personality_array_count (0) { }
};
void
ScanIndex(const lldb::ProcessSP &process_sp);
bool
GetCompactUnwindInfoForFunction (Target &target, Address address, FunctionInfo &unwind_info);
lldb::offset_t
BinarySearchRegularSecondPage (uint32_t entry_page_offset, uint32_t entry_count, uint32_t function_offset, uint32_t *entry_func_start_offset, uint32_t *entry_func_end_offset);
uint32_t
BinarySearchCompressedSecondPage (uint32_t entry_page_offset, uint32_t entry_count, uint32_t function_offset_to_find, uint32_t function_offset_base, uint32_t *entry_func_start_offset, uint32_t *entry_func_end_offset);
uint32_t
GetLSDAForFunctionOffset (uint32_t lsda_offset, uint32_t lsda_count, uint32_t function_offset);
bool
CreateUnwindPlan_x86_64 (Target &target, FunctionInfo &function_info, UnwindPlan &unwind_plan, Address pc_or_function_start);
bool
CreateUnwindPlan_i386 (Target &target, FunctionInfo &function_info, UnwindPlan &unwind_plan, Address pc_or_function_start);
ObjectFile &m_objfile;
lldb::SectionSP m_section_sp;
lldb::DataBufferSP m_section_contents_if_encrypted; // if the binary is encrypted, read the sect contents
// out of live memory and cache them here
Mutex m_mutex;
std::vector<UnwindIndex> m_indexes;
LazyBool m_indexes_computed; // eLazyBoolYes once we've tried to parse the unwind info
// eLazyBoolNo means we cannot parse the unwind info & should not retry
// eLazyBoolCalculate means we haven't tried to parse it yet
DataExtractor m_unwindinfo_data;
bool m_unwindinfo_data_computed; // true once we've mapped in the unwindinfo data
UnwindHeader m_unwind_header;
};
} // namespace lldb_private
#endif // liblldb_CompactUnwindInfo_h_
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