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platform_system_core/libunwindstack/DwarfCfa.h
Christopher Ferris 4cc36d2b43 Fix handling of load bias values. 
It turns out that for the dwarf information, if a FDE indicates it's pc
relative, then pc has to be incremented by the load bias. If not, then
it should not be incremented.

Previously, the code always subtracted load bias values from pcs, and assumed
that all fdes were incremented by load bias values. The new code actually
reads the fdes and adjusted the pcs in the fde and in the eh frame hdr so
that load bias values are already handled properly.

In addition, add dumping of arm exidx values in unwind_reg_info. This allowed
verifying that the debug frame in those elf files was being handled properly.

Added a new unit test that only has a debug frame that has a non-zero load
bias and has fde entries that do not have pc relative encoding.

Fix a couple of other small bugs.

Bug: 109824792

Test: All libbacktrace/libunwindstack unit tests pass.
Test: Ran ART 137-cfi test and 004-ThreadStress.
Test: Verify that displaying the fde start and end pc actually match the
Test: real data for fde that have pc relative set, and that don't.
Test: Verified that the unwind information for arm exidx matches the
Test: debug frame data.

Change-Id: I707555286b5cb05df9f25489e8c5ede753cfe0fb
2018-06-11 18:53:55 -07:00

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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _LIBUNWINDSTACK_DWARF_CFA_H
#define _LIBUNWINDSTACK_DWARF_CFA_H
#include <stdint.h>
#include <stack>
#include <string>
#include <type_traits>
#include <vector>
#include <unwindstack/DwarfError.h>
#include <unwindstack/DwarfLocation.h>
#include <unwindstack/DwarfMemory.h>
#include <unwindstack/DwarfStructs.h>
namespace unwindstack {
// DWARF Standard home: http://dwarfstd.org/
// This code is based on DWARF 4: http://http://dwarfstd.org/doc/DWARF4.pdf
// See section 6.4.2.1 for a description of the DW_CFA_xxx values.
class DwarfCfaInfo {
public:
enum DisplayType : uint8_t {
DWARF_DISPLAY_NONE = 0,
DWARF_DISPLAY_REGISTER,
DWARF_DISPLAY_NUMBER,
DWARF_DISPLAY_SIGNED_NUMBER,
DWARF_DISPLAY_EVAL_BLOCK,
DWARF_DISPLAY_ADDRESS,
DWARF_DISPLAY_SET_LOC,
DWARF_DISPLAY_ADVANCE_LOC,
};
struct Info {
const char* name;
uint8_t supported_version;
uint8_t num_operands;
uint8_t operands[2];
uint8_t display_operands[2];
};
const static Info kTable[64];
};
template <typename AddressType>
class DwarfCfa {
// Signed version of AddressType
typedef typename std::make_signed<AddressType>::type SignedType;
public:
DwarfCfa(DwarfMemory* memory, const DwarfFde* fde) : memory_(memory), fde_(fde) {}
virtual ~DwarfCfa() = default;
bool GetLocationInfo(uint64_t pc, uint64_t start_offset, uint64_t end_offset,
dwarf_loc_regs_t* loc_regs);
bool Log(uint32_t indent, uint64_t pc, uint64_t start_offset, uint64_t end_offset);
const DwarfErrorData& last_error() { return last_error_; }
DwarfErrorCode LastErrorCode() { return last_error_.code; }
uint64_t LastErrorAddress() { return last_error_.address; }
AddressType cur_pc() { return cur_pc_; }
void set_cie_loc_regs(const dwarf_loc_regs_t* cie_loc_regs) { cie_loc_regs_ = cie_loc_regs; }
protected:
std::string GetOperandString(uint8_t operand, uint64_t value, uint64_t* cur_pc);
bool LogOffsetRegisterString(uint32_t indent, uint64_t cfa_offset, uint8_t reg);
bool LogInstruction(uint32_t indent, uint64_t cfa_offset, uint8_t op, uint64_t* cur_pc);
private:
DwarfErrorData last_error_;
DwarfMemory* memory_;
const DwarfFde* fde_;
AddressType cur_pc_;
const dwarf_loc_regs_t* cie_loc_regs_ = nullptr;
std::vector<AddressType> operands_;
std::stack<dwarf_loc_regs_t> loc_reg_state_;
// CFA processing functions.
bool cfa_nop(dwarf_loc_regs_t*);
bool cfa_set_loc(dwarf_loc_regs_t*);
bool cfa_advance_loc(dwarf_loc_regs_t*);
bool cfa_offset(dwarf_loc_regs_t*);
bool cfa_restore(dwarf_loc_regs_t*);
bool cfa_undefined(dwarf_loc_regs_t*);
bool cfa_same_value(dwarf_loc_regs_t*);
bool cfa_register(dwarf_loc_regs_t*);
bool cfa_remember_state(dwarf_loc_regs_t*);
bool cfa_restore_state(dwarf_loc_regs_t*);
bool cfa_def_cfa(dwarf_loc_regs_t*);
bool cfa_def_cfa_register(dwarf_loc_regs_t*);
bool cfa_def_cfa_offset(dwarf_loc_regs_t*);
bool cfa_def_cfa_expression(dwarf_loc_regs_t*);
bool cfa_expression(dwarf_loc_regs_t*);
bool cfa_offset_extended_sf(dwarf_loc_regs_t*);
bool cfa_def_cfa_sf(dwarf_loc_regs_t*);
bool cfa_def_cfa_offset_sf(dwarf_loc_regs_t*);
bool cfa_val_offset(dwarf_loc_regs_t*);
bool cfa_val_offset_sf(dwarf_loc_regs_t*);
bool cfa_val_expression(dwarf_loc_regs_t*);
bool cfa_gnu_negative_offset_extended(dwarf_loc_regs_t*);
using process_func = bool (DwarfCfa::*)(dwarf_loc_regs_t*);
constexpr static process_func kCallbackTable[64] = {
// 0x00 DW_CFA_nop
&DwarfCfa::cfa_nop,
// 0x01 DW_CFA_set_loc
&DwarfCfa::cfa_set_loc,
// 0x02 DW_CFA_advance_loc1
&DwarfCfa::cfa_advance_loc,
// 0x03 DW_CFA_advance_loc2
&DwarfCfa::cfa_advance_loc,
// 0x04 DW_CFA_advance_loc4
&DwarfCfa::cfa_advance_loc,
// 0x05 DW_CFA_offset_extended
&DwarfCfa::cfa_offset,
// 0x06 DW_CFA_restore_extended
&DwarfCfa::cfa_restore,
// 0x07 DW_CFA_undefined
&DwarfCfa::cfa_undefined,
// 0x08 DW_CFA_same_value
&DwarfCfa::cfa_same_value,
// 0x09 DW_CFA_register
&DwarfCfa::cfa_register,
// 0x0a DW_CFA_remember_state
&DwarfCfa::cfa_remember_state,
// 0x0b DW_CFA_restore_state
&DwarfCfa::cfa_restore_state,
// 0x0c DW_CFA_def_cfa
&DwarfCfa::cfa_def_cfa,
// 0x0d DW_CFA_def_cfa_register
&DwarfCfa::cfa_def_cfa_register,
// 0x0e DW_CFA_def_cfa_offset
&DwarfCfa::cfa_def_cfa_offset,
// 0x0f DW_CFA_def_cfa_expression
&DwarfCfa::cfa_def_cfa_expression,
// 0x10 DW_CFA_expression
&DwarfCfa::cfa_expression,
// 0x11 DW_CFA_offset_extended_sf
&DwarfCfa::cfa_offset_extended_sf,
// 0x12 DW_CFA_def_cfa_sf
&DwarfCfa::cfa_def_cfa_sf,
// 0x13 DW_CFA_def_cfa_offset_sf
&DwarfCfa::cfa_def_cfa_offset_sf,
// 0x14 DW_CFA_val_offset
&DwarfCfa::cfa_val_offset,
// 0x15 DW_CFA_val_offset_sf
&DwarfCfa::cfa_val_offset_sf,
// 0x16 DW_CFA_val_expression
&DwarfCfa::cfa_val_expression,
// 0x17 illegal cfa
nullptr,
// 0x18 illegal cfa
nullptr,
// 0x19 illegal cfa
nullptr,
// 0x1a illegal cfa
nullptr,
// 0x1b illegal cfa
nullptr,
// 0x1c DW_CFA_lo_user (Treat this as illegal)
nullptr,
// 0x1d illegal cfa
nullptr,
// 0x1e illegal cfa
nullptr,
// 0x1f illegal cfa
nullptr,
// 0x20 illegal cfa
nullptr,
// 0x21 illegal cfa
nullptr,
// 0x22 illegal cfa
nullptr,
// 0x23 illegal cfa
nullptr,
// 0x24 illegal cfa
nullptr,
// 0x25 illegal cfa
nullptr,
// 0x26 illegal cfa
nullptr,
// 0x27 illegal cfa
nullptr,
// 0x28 illegal cfa
nullptr,
// 0x29 illegal cfa
nullptr,
// 0x2a illegal cfa
nullptr,
// 0x2b illegal cfa
nullptr,
// 0x2c illegal cfa
nullptr,
// 0x2d DW_CFA_GNU_window_save (Treat this as illegal)
nullptr,
// 0x2e DW_CFA_GNU_args_size
&DwarfCfa::cfa_nop,
// 0x2f DW_CFA_GNU_negative_offset_extended
&DwarfCfa::cfa_gnu_negative_offset_extended,
// 0x30 illegal cfa
nullptr,
// 0x31 illegal cfa
nullptr,
// 0x32 illegal cfa
nullptr,
// 0x33 illegal cfa
nullptr,
// 0x34 illegal cfa
nullptr,
// 0x35 illegal cfa
nullptr,
// 0x36 illegal cfa
nullptr,
// 0x37 illegal cfa
nullptr,
// 0x38 illegal cfa
nullptr,
// 0x39 illegal cfa
nullptr,
// 0x3a illegal cfa
nullptr,
// 0x3b illegal cfa
nullptr,
// 0x3c illegal cfa
nullptr,
// 0x3d illegal cfa
nullptr,
// 0x3e illegal cfa
nullptr,
// 0x3f DW_CFA_hi_user (Treat this as illegal)
nullptr,
};
};
} // namespace unwindstack
#endif // _LIBUNWINDSTACK_DWARF_CFA_H
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