530 lines
18 KiB
C++
530 lines
18 KiB
C++
//===--------------------------- DwarfParser.hpp --------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//
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// Parses DWARF CFIs (FDEs and CIEs).
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//
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//===----------------------------------------------------------------------===//
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#ifndef __DWARF_PARSER_HPP__
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#define __DWARF_PARSER_HPP__
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#include <cstdint>
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#include <cstdlib>
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#include "dwarf2.h"
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#include "AddressSpace.hpp"
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namespace _Unwind {
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/// CFI_Parser does basic parsing of a CFI (Call Frame Information) records.
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/// See Dwarf Spec for details:
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/// http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
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///
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template <typename A, typename R> class CFI_Parser {
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public:
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typedef typename A::pint_t pint_t;
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/// Information encoded in a CIE (Common Information Entry)
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struct CIE_Info {
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pint_t cieStart;
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pint_t cieLength;
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pint_t cieInstructions;
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pint_t personality;
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uint32_t codeAlignFactor;
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int dataAlignFactor;
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uint8_t pointerEncoding;
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uint8_t lsdaEncoding;
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uint8_t personalityEncoding;
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uint8_t personalityOffsetInCIE;
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bool isSignalFrame;
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bool fdesHaveAugmentationData;
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};
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/// Information about an FDE (Frame Description Entry)
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struct FDE_Info {
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pint_t fdeStart;
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pint_t fdeLength;
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pint_t fdeInstructions;
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pint_t pcStart;
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pint_t pcEnd;
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pint_t lsda;
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};
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/// Information about a frame layout and registers saved determined
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/// by "running" the DWARF FDE "instructions"
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enum {
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kMaxRegisterNumber = R::LAST_REGISTER + 1
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};
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enum RegisterSavedWhere {
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kRegisterUnused,
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kRegisterInCFA,
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kRegisterOffsetFromCFA,
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kRegisterInRegister,
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kRegisterAtExpression,
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kRegisterIsExpression,
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};
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struct RegisterLocation {
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RegisterSavedWhere location;
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int64_t value;
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};
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struct PrologInfo {
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uint32_t cfaRegister;
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int32_t cfaRegisterOffset; // CFA = (cfaRegister)+cfaRegisterOffset
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int64_t cfaExpression; // CFA = expression
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uint32_t spExtraArgSize;
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uint32_t codeOffsetAtStackDecrement;
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RegisterLocation savedRegisters[kMaxRegisterNumber];
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};
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struct PrologInfoStackEntry {
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PrologInfoStackEntry(PrologInfoStackEntry *n, const PrologInfo &i)
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: next(n), info(i) {}
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PrologInfoStackEntry *next;
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PrologInfo info;
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};
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static void findPCRange(A &, pint_t, pint_t &, pint_t &);
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static bool decodeFDE(A &, pint_t, FDE_Info *, CIE_Info *,
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unw_proc_info_t *ctx);
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static bool parseFDEInstructions(A &, const FDE_Info &, const CIE_Info &,
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pint_t, PrologInfo *, unw_proc_info_t *ctx);
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static bool parseCIE(A &, pint_t, CIE_Info *);
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private:
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static bool parseInstructions(A &, pint_t, pint_t, const CIE_Info &, pint_t,
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PrologInfoStackEntry *&, PrologInfo *,
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unw_proc_info_t *ctx);
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};
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///
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/// Parse a FDE and return the last PC it covers.
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///
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template <typename A, typename R>
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void CFI_Parser<A, R>::findPCRange(A &addressSpace, pint_t fde, pint_t &pcStart,
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pint_t &pcEnd) {
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pcStart = 0;
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pcEnd = 0;
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pint_t p = fde;
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uint64_t cfiLength = addressSpace.get32(p);
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p += 4;
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if (cfiLength == 0xffffffff) {
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// 0xffffffff means length is really the next 8 Bytes.
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cfiLength = addressSpace.get64(p);
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p += 8;
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}
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if (cfiLength == 0)
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return;
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uint32_t ciePointer = addressSpace.get32(p);
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if (ciePointer == 0)
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return;
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pint_t nextCFI = p + cfiLength;
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pint_t cieStart = p - ciePointer;
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typename CFI_Parser<A, R>::CIE_Info cieInfo;
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if (!parseCIE(addressSpace, cieStart, &cieInfo))
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return;
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p += 4;
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// Parse pc begin and range.
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pcStart = addressSpace.getEncodedP(p, nextCFI, cieInfo.pointerEncoding, NULL);
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pcEnd = pcStart + addressSpace.getEncodedP(
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p, nextCFI, cieInfo.pointerEncoding & 0x0F, NULL);
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}
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///
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/// Parse a FDE into a CIE_Info and an FDE_Info
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///
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template <typename A, typename R>
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bool CFI_Parser<A, R>::decodeFDE(A &addressSpace, pint_t fdeStart,
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FDE_Info *fdeInfo, CIE_Info *cieInfo,
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unw_proc_info_t *ctx) {
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pint_t p = fdeStart;
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uint64_t cfiLength = addressSpace.get32(p);
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p += 4;
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if (cfiLength == 0xffffffff) {
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// 0xffffffff means length is really the next 8 Bytes.
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cfiLength = addressSpace.get64(p);
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p += 8;
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}
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if (cfiLength == 0)
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return false;
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uint32_t ciePointer = addressSpace.get32(p);
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if (ciePointer == 0)
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return false;
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pint_t nextCFI = p + cfiLength;
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pint_t cieStart = p - ciePointer;
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if (!parseCIE(addressSpace, cieStart, cieInfo))
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return false;
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p += 4;
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// Parse pc begin and range.
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pint_t pcStart =
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addressSpace.getEncodedP(p, nextCFI, cieInfo->pointerEncoding, ctx);
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pint_t pcRange = addressSpace.getEncodedP(
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p, nextCFI, cieInfo->pointerEncoding & 0x0F, ctx);
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// Parse rest of info.
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fdeInfo->lsda = 0;
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// Check for augmentation length
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if (cieInfo->fdesHaveAugmentationData) {
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uintptr_t augLen = addressSpace.getULEB128(p, nextCFI);
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pint_t endOfAug = p + augLen;
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if (cieInfo->lsdaEncoding != 0) {
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// Peek at value (without indirection). Zero means no LSDA.
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pint_t lsdaStart = p;
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if (addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding & 0x0F,
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ctx) != 0) {
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// Reset pointer and re-parse LSDA address.
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p = lsdaStart;
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fdeInfo->lsda =
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addressSpace.getEncodedP(p, nextCFI, cieInfo->lsdaEncoding, ctx);
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}
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}
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p = endOfAug;
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}
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fdeInfo->fdeStart = fdeStart;
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fdeInfo->fdeLength = nextCFI - fdeStart;
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fdeInfo->fdeInstructions = p;
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fdeInfo->pcStart = pcStart;
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fdeInfo->pcEnd = pcStart + pcRange;
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return true;
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}
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/// Extract info from a CIE
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template <typename A, typename R>
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bool CFI_Parser<A, R>::parseCIE(A &addressSpace, pint_t cie,
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CIE_Info *cieInfo) {
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cieInfo->pointerEncoding = 0;
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cieInfo->lsdaEncoding = 0;
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cieInfo->personalityEncoding = 0;
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cieInfo->personalityOffsetInCIE = 0;
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cieInfo->personality = 0;
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cieInfo->codeAlignFactor = 0;
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cieInfo->dataAlignFactor = 0;
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cieInfo->isSignalFrame = false;
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cieInfo->fdesHaveAugmentationData = false;
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cieInfo->cieStart = cie;
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pint_t p = cie;
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uint64_t cieLength = addressSpace.get32(p);
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p += 4;
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pint_t cieContentEnd = p + cieLength;
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if (cieLength == 0xffffffff) {
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// 0xffffffff means length is really the next 8 Bytes.
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cieLength = addressSpace.get64(p);
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p += 8;
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cieContentEnd = p + cieLength;
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}
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if (cieLength == 0)
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return true;
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// CIE ID is always 0
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if (addressSpace.get32(p) != 0)
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return false;
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p += 4;
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// Version is always 1 or 3
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uint8_t version = addressSpace.get8(p);
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if (version != 1 && version != 3)
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return false;
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++p;
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// Save start of augmentation string and find end.
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pint_t strStart = p;
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while (addressSpace.get8(p) != 0)
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++p;
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++p;
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// Parse code aligment factor
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cieInfo->codeAlignFactor = addressSpace.getULEB128(p, cieContentEnd);
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// Parse data alignment factor
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cieInfo->dataAlignFactor = addressSpace.getSLEB128(p, cieContentEnd);
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// Parse return address register
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addressSpace.getULEB128(p, cieContentEnd);
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// Parse augmentation data based on augmentation string.
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if (addressSpace.get8(strStart) == 'z') {
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// parse augmentation data length
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addressSpace.getULEB128(p, cieContentEnd);
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for (pint_t s = strStart; addressSpace.get8(s) != '\0'; ++s) {
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switch (addressSpace.get8(s)) {
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case 'z':
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cieInfo->fdesHaveAugmentationData = true;
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break;
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case 'P':
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cieInfo->personalityEncoding = addressSpace.get8(p);
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++p;
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cieInfo->personalityOffsetInCIE = p - cie;
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cieInfo->personality = addressSpace.getEncodedP(
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p, cieContentEnd, cieInfo->personalityEncoding, NULL);
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break;
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case 'L':
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cieInfo->lsdaEncoding = addressSpace.get8(p);
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++p;
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break;
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case 'R':
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cieInfo->pointerEncoding = addressSpace.get8(p);
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++p;
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break;
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case 'S':
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cieInfo->isSignalFrame = true;
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break;
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default:
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// ignore unknown letters
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break;
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}
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}
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}
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cieInfo->cieLength = cieContentEnd - cieInfo->cieStart;
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cieInfo->cieInstructions = p;
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return true;
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}
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/// "Run" the dwarf instructions and create the abstact PrologInfo for an FDE.
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template <typename A, typename R>
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bool CFI_Parser<A, R>::parseFDEInstructions(A &addressSpace,
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const FDE_Info &fdeInfo,
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const CIE_Info &cieInfo,
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pint_t upToPC, PrologInfo *results,
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unw_proc_info_t *ctx) {
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// Clear results.
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memset(results, 0, sizeof(*results));
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PrologInfoStackEntry *rememberStack = NULL;
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// First parse the CIE then FDE instructions.
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if (!parseInstructions(addressSpace, cieInfo.cieInstructions,
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cieInfo.cieStart + cieInfo.cieLength, cieInfo,
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(pint_t)(-1), rememberStack, results, ctx))
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return false;
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return parseInstructions(addressSpace, fdeInfo.fdeInstructions,
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fdeInfo.fdeStart + fdeInfo.fdeLength, cieInfo,
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upToPC - fdeInfo.pcStart, rememberStack, results,
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ctx);
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}
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/// "Run" the DWARF instructions.
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template <typename A, typename R>
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bool
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CFI_Parser<A, R>::parseInstructions(A &addressSpace, pint_t instructions,
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pint_t instructionsEnd,
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const CIE_Info &cieInfo, pint_t pcoffset,
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PrologInfoStackEntry *&rememberStack,
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PrologInfo *results, unw_proc_info_t *ctx) {
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pint_t p = instructions;
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uint32_t codeOffset = 0;
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PrologInfo initialState = *results;
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// See Dwarf Spec, section 6.4.2 for details on unwind opcodes.
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while (p < instructionsEnd && codeOffset < pcoffset) {
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uint64_t reg;
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uint64_t reg2;
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int64_t offset;
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uint64_t length;
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uint8_t opcode = addressSpace.get8(p);
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uint8_t operand;
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PrologInfoStackEntry *entry;
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++p;
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switch (opcode) {
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case DW_CFA_nop:
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break;
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case DW_CFA_set_loc:
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codeOffset = addressSpace.getEncodedP(p, instructionsEnd,
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cieInfo.pointerEncoding, ctx);
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break;
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case DW_CFA_advance_loc1:
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codeOffset += (addressSpace.get8(p) * cieInfo.codeAlignFactor);
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p += 1;
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break;
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case DW_CFA_advance_loc2:
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codeOffset += (addressSpace.get16(p) * cieInfo.codeAlignFactor);
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p += 2;
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break;
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case DW_CFA_advance_loc4:
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codeOffset += (addressSpace.get32(p) * cieInfo.codeAlignFactor);
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p += 4;
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break;
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case DW_CFA_offset_extended:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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offset =
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addressSpace.getULEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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if (reg > kMaxRegisterNumber)
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return false;
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results->savedRegisters[reg].location = kRegisterInCFA;
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results->savedRegisters[reg].value = offset;
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break;
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case DW_CFA_restore_extended:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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results->savedRegisters[reg] = initialState.savedRegisters[reg];
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break;
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case DW_CFA_undefined:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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results->savedRegisters[reg].location = kRegisterUnused;
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break;
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case DW_CFA_same_value:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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// "same value" means register was stored in frame, but its current
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// value has not changed, so no need to restore from frame.
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// We model this as if the register was never saved.
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results->savedRegisters[reg].location = kRegisterUnused;
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break;
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case DW_CFA_register:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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reg2 = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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if (reg2 > kMaxRegisterNumber)
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return false;
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results->savedRegisters[reg].location = kRegisterInRegister;
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results->savedRegisters[reg].value = reg2;
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break;
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case DW_CFA_remember_state:
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// avoid operator new, because that would be an upward dependency
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entry = (PrologInfoStackEntry *)malloc(sizeof(PrologInfoStackEntry));
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if (entry == NULL)
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return false;
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entry->next = rememberStack;
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entry->info = *results;
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rememberStack = entry;
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break;
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case DW_CFA_restore_state:
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if (rememberStack == NULL)
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return false;
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{
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PrologInfoStackEntry *top = rememberStack;
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*results = top->info;
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rememberStack = top->next;
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free((char *)top);
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}
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break;
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case DW_CFA_def_cfa:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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offset = addressSpace.getULEB128(p, instructionsEnd);
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if (reg > kMaxRegisterNumber)
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return false;
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results->cfaRegister = reg;
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results->cfaRegisterOffset = offset;
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break;
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case DW_CFA_def_cfa_register:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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results->cfaRegister = reg;
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break;
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case DW_CFA_def_cfa_offset:
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results->cfaRegisterOffset = addressSpace.getULEB128(p, instructionsEnd);
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results->codeOffsetAtStackDecrement = codeOffset;
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break;
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case DW_CFA_def_cfa_expression:
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results->cfaRegister = 0;
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results->cfaExpression = p;
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length = addressSpace.getULEB128(p, instructionsEnd);
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p += length;
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break;
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case DW_CFA_expression:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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results->savedRegisters[reg].location = kRegisterAtExpression;
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results->savedRegisters[reg].value = p;
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length = addressSpace.getULEB128(p, instructionsEnd);
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p += length;
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break;
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case DW_CFA_offset_extended_sf:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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offset =
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addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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results->savedRegisters[reg].location = kRegisterInCFA;
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results->savedRegisters[reg].value = offset;
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break;
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case DW_CFA_def_cfa_sf:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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offset =
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addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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if (reg > kMaxRegisterNumber)
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return false;
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results->cfaRegister = reg;
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results->cfaRegisterOffset = offset;
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break;
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case DW_CFA_def_cfa_offset_sf:
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results->cfaRegisterOffset =
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addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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results->codeOffsetAtStackDecrement = codeOffset;
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break;
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case DW_CFA_val_offset:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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offset =
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addressSpace.getULEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
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results->savedRegisters[reg].value = offset;
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break;
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case DW_CFA_val_offset_sf:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
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if (reg > kMaxRegisterNumber)
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return false;
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offset =
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addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
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results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
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results->savedRegisters[reg].value = offset;
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break;
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case DW_CFA_val_expression:
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reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
|
|
if (reg > kMaxRegisterNumber)
|
|
return false;
|
|
results->savedRegisters[reg].location = kRegisterIsExpression;
|
|
results->savedRegisters[reg].value = p;
|
|
length = addressSpace.getULEB128(p, instructionsEnd);
|
|
p += length;
|
|
break;
|
|
case DW_CFA_GNU_args_size:
|
|
offset = addressSpace.getULEB128(p, instructionsEnd);
|
|
results->spExtraArgSize = offset;
|
|
break;
|
|
case DW_CFA_GNU_negative_offset_extended:
|
|
reg = R::dwarf2regno(addressSpace.getULEB128(p, instructionsEnd));
|
|
if (reg > kMaxRegisterNumber)
|
|
return false;
|
|
offset =
|
|
addressSpace.getULEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
|
|
results->savedRegisters[reg].location = kRegisterInCFA;
|
|
results->savedRegisters[reg].value = -offset;
|
|
break;
|
|
default:
|
|
operand = opcode & 0x3F;
|
|
switch (opcode & 0xC0) {
|
|
case DW_CFA_offset:
|
|
reg = R::dwarf2regno(operand);
|
|
if (reg > kMaxRegisterNumber)
|
|
return false;
|
|
offset = addressSpace.getULEB128(p, instructionsEnd) *
|
|
cieInfo.dataAlignFactor;
|
|
results->savedRegisters[reg].location = kRegisterInCFA;
|
|
results->savedRegisters[reg].value = offset;
|
|
break;
|
|
case DW_CFA_advance_loc:
|
|
codeOffset += operand * cieInfo.codeAlignFactor;
|
|
break;
|
|
case DW_CFA_restore:
|
|
reg = R::dwarf2regno(operand);
|
|
if (reg > kMaxRegisterNumber)
|
|
return false;
|
|
results->savedRegisters[reg] = initialState.savedRegisters[reg];
|
|
break;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
} // namespace _Unwind
|
|
|
|
#endif // __DWARF_PARSER_HPP__
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