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Diffstat (limited to 'tools/profiler/core/EHABIStackWalk.cpp')
| -rw-r--r-- | tools/profiler/core/EHABIStackWalk.cpp | 678 |
1 files changed, 0 insertions, 678 deletions
diff --git a/tools/profiler/core/EHABIStackWalk.cpp b/tools/profiler/core/EHABIStackWalk.cpp deleted file mode 100644 index 76068cdea..000000000 --- a/tools/profiler/core/EHABIStackWalk.cpp +++ /dev/null @@ -1,678 +0,0 @@ -/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ -/* vim: set ts=8 sts=2 et sw=2 tw=80: */ -/* This Source Code Form is subject to the terms of the Mozilla Public - * License, v. 2.0. If a copy of the MPL was not distributed with this - * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ - -/* - * This is an implementation of stack unwinding according to a subset - * of the ARM Exception Handling ABI, as described in: - * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf - * - * This handles only the ARM-defined "personality routines" (chapter - * 9), and don't track the value of FP registers, because profiling - * needs only chain of PC/SP values. - * - * Because the exception handling info may not be accurate for all - * possible places where an async signal could occur (e.g., in a - * prologue or epilogue), this bounds-checks all stack accesses. - * - * This file uses "struct" for structures in the exception tables and - * "class" otherwise. We should avoid violating the C++11 - * standard-layout rules in the former. - */ - -#include "EHABIStackWalk.h" - -#include "shared-libraries.h" -#include "platform.h" - -#include "mozilla/Atomics.h" -#include "mozilla/Attributes.h" -#include "mozilla/DebugOnly.h" -#include "mozilla/EndianUtils.h" - -#include <algorithm> -#include <elf.h> -#include <stdint.h> -#include <vector> -#include <string> - -#ifndef PT_ARM_EXIDX -#define PT_ARM_EXIDX 0x70000001 -#endif - -// Bug 1082817: ICS B2G has a buggy linker that doesn't always ensure -// that the EXIDX is sorted by address, as the spec requires. So in -// that case we build and sort an array of pointers into the index, -// and binary-search that; otherwise, we search the index in place -// (avoiding the time and space overhead of the indirection). -#if defined(ANDROID_VERSION) && ANDROID_VERSION < 16 -#define HAVE_UNSORTED_EXIDX -#endif - -namespace mozilla { - -struct PRel31 { - uint32_t mBits; - bool topBit() const { return mBits & 0x80000000; } - uint32_t value() const { return mBits & 0x7fffffff; } - int32_t offset() const { return (static_cast<int32_t>(mBits) << 1) >> 1; } - const void *compute() const { - return reinterpret_cast<const char *>(this) + offset(); - } -private: - PRel31(const PRel31 &copied) = delete; - PRel31() = delete; -}; - -struct EHEntry { - PRel31 startPC; - PRel31 exidx; -private: - EHEntry(const EHEntry &copied) = delete; - EHEntry() = delete; -}; - -class EHState { - // Note that any core register can be used as a "frame pointer" to - // influence the unwinding process, so this must track all of them. - uint32_t mRegs[16]; -public: - bool unwind(const EHEntry *aEntry, const void *stackBase); - uint32_t &operator[](int i) { return mRegs[i]; } - const uint32_t &operator[](int i) const { return mRegs[i]; } - EHState(const mcontext_t &); -}; - -enum { - R_SP = 13, - R_LR = 14, - R_PC = 15 -}; - -#ifdef HAVE_UNSORTED_EXIDX -class EHEntryHandle { - const EHEntry *mValue; -public: - EHEntryHandle(const EHEntry *aEntry) : mValue(aEntry) { } - const EHEntry *value() const { return mValue; } -}; - -bool operator<(const EHEntryHandle &lhs, const EHEntryHandle &rhs) { - return lhs.value()->startPC.compute() < rhs.value()->startPC.compute(); -} -#endif - -class EHTable { - uint32_t mStartPC; - uint32_t mEndPC; - uint32_t mLoadOffset; -#ifdef HAVE_UNSORTED_EXIDX - // In principle we should be able to binary-search the index section in - // place, but the ICS toolchain's linker is noncompliant and produces - // indices that aren't entirely sorted (e.g., libc). So we have this: - std::vector<EHEntryHandle> mEntries; - typedef std::vector<EHEntryHandle>::const_iterator EntryIterator; - EntryIterator entriesBegin() const { return mEntries.begin(); } - EntryIterator entriesEnd() const { return mEntries.end(); } - static const EHEntry* entryGet(EntryIterator aEntry) { - return aEntry->value(); - } -#else - typedef const EHEntry *EntryIterator; - EntryIterator mEntriesBegin, mEntriesEnd; - EntryIterator entriesBegin() const { return mEntriesBegin; } - EntryIterator entriesEnd() const { return mEntriesEnd; } - static const EHEntry* entryGet(EntryIterator aEntry) { return aEntry; } -#endif - std::string mName; -public: - EHTable(const void *aELF, size_t aSize, const std::string &aName); - const EHEntry *lookup(uint32_t aPC) const; - bool isValid() const { return entriesEnd() != entriesBegin(); } - const std::string &name() const { return mName; } - uint32_t startPC() const { return mStartPC; } - uint32_t endPC() const { return mEndPC; } - uint32_t loadOffset() const { return mLoadOffset; } -}; - -class EHAddrSpace { - std::vector<uint32_t> mStarts; - std::vector<EHTable> mTables; - static mozilla::Atomic<const EHAddrSpace*> sCurrent; -public: - explicit EHAddrSpace(const std::vector<EHTable>& aTables); - const EHTable *lookup(uint32_t aPC) const; - static void Update(); - static const EHAddrSpace *Get(); -}; - - -void EHABIStackWalkInit() -{ - EHAddrSpace::Update(); -} - -size_t EHABIStackWalk(const mcontext_t &aContext, void *stackBase, - void **aSPs, void **aPCs, const size_t aNumFrames) -{ - const EHAddrSpace *space = EHAddrSpace::Get(); - EHState state(aContext); - size_t count = 0; - - while (count < aNumFrames) { - uint32_t pc = state[R_PC], sp = state[R_SP]; - aPCs[count] = reinterpret_cast<void *>(pc); - aSPs[count] = reinterpret_cast<void *>(sp); - count++; - - if (!space) - break; - // TODO: cache these lookups. Binary-searching libxul is - // expensive (possibly more expensive than doing the actual - // unwind), and even a small cache should help. - const EHTable *table = space->lookup(pc); - if (!table) - break; - const EHEntry *entry = table->lookup(pc); - if (!entry) - break; - if (!state.unwind(entry, stackBase)) - break; - } - - return count; -} - - -class EHInterp { -public: - // Note that stackLimit is exclusive and stackBase is inclusive - // (i.e, stackLimit < SP <= stackBase), following the convention - // set by the AAPCS spec. - EHInterp(EHState &aState, const EHEntry *aEntry, - uint32_t aStackLimit, uint32_t aStackBase) - : mState(aState), - mStackLimit(aStackLimit), - mStackBase(aStackBase), - mNextWord(0), - mWordsLeft(0), - mFailed(false) - { - const PRel31 &exidx = aEntry->exidx; - uint32_t firstWord; - - if (exidx.mBits == 1) { // EXIDX_CANTUNWIND - mFailed = true; - return; - } - if (exidx.topBit()) { - firstWord = exidx.mBits; - } else { - mNextWord = reinterpret_cast<const uint32_t *>(exidx.compute()); - firstWord = *mNextWord++; - } - - switch (firstWord >> 24) { - case 0x80: // short - mWord = firstWord << 8; - mBytesLeft = 3; - break; - case 0x81: case 0x82: // long; catch descriptor size ignored - mWord = firstWord << 16; - mBytesLeft = 2; - mWordsLeft = (firstWord >> 16) & 0xff; - break; - default: - // unknown personality - mFailed = true; - } - } - - bool unwind(); - -private: - // TODO: GCC has been observed not CSEing repeated reads of - // mState[R_SP] with writes to mFailed between them, suggesting that - // it hasn't determined that they can't alias and is thus missing - // optimization opportunities. So, we may want to flatten EHState - // into this class; this may also make the code simpler. - EHState &mState; - uint32_t mStackLimit; - uint32_t mStackBase; - const uint32_t *mNextWord; - uint32_t mWord; - uint8_t mWordsLeft; - uint8_t mBytesLeft; - bool mFailed; - - enum { - I_ADDSP = 0x00, // 0sxxxxxx (subtract if s) - M_ADDSP = 0x80, - I_POPMASK = 0x80, // 1000iiii iiiiiiii (if any i set) - M_POPMASK = 0xf0, - I_MOVSP = 0x90, // 1001nnnn - M_MOVSP = 0xf0, - I_POPN = 0xa0, // 1010lnnn - M_POPN = 0xf0, - I_FINISH = 0xb0, // 10110000 - I_POPLO = 0xb1, // 10110001 0000iiii (if any i set) - I_ADDSPBIG = 0xb2, // 10110010 uleb128 - I_POPFDX = 0xb3, // 10110011 sssscccc - I_POPFDX8 = 0xb8, // 10111nnn - M_POPFDX8 = 0xf8, - // "Intel Wireless MMX" extensions omitted. - I_POPFDD = 0xc8, // 1100100h sssscccc - M_POPFDD = 0xfe, - I_POPFDD8 = 0xd0, // 11010nnn - M_POPFDD8 = 0xf8 - }; - - uint8_t next() { - if (mBytesLeft == 0) { - if (mWordsLeft == 0) { - return I_FINISH; - } - mWordsLeft--; - mWord = *mNextWord++; - mBytesLeft = 4; - } - mBytesLeft--; - mWord = (mWord << 8) | (mWord >> 24); // rotate - return mWord; - } - - uint32_t &vSP() { return mState[R_SP]; } - uint32_t *ptrSP() { return reinterpret_cast<uint32_t *>(vSP()); } - - void checkStackBase() { if (vSP() > mStackBase) mFailed = true; } - void checkStackLimit() { if (vSP() <= mStackLimit) mFailed = true; } - void checkStackAlign() { if ((vSP() & 3) != 0) mFailed = true; } - void checkStack() { - checkStackBase(); - checkStackLimit(); - checkStackAlign(); - } - - void popRange(uint8_t first, uint8_t last, uint16_t mask) { - bool hasSP = false; - uint32_t tmpSP; - if (mask == 0) - mFailed = true; - for (uint8_t r = first; r <= last; ++r) { - if (mask & 1) { - if (r == R_SP) { - hasSP = true; - tmpSP = *ptrSP(); - } else - mState[r] = *ptrSP(); - vSP() += 4; - checkStackBase(); - if (mFailed) - return; - } - mask >>= 1; - } - if (hasSP) { - vSP() = tmpSP; - checkStack(); - } - } -}; - - -bool EHState::unwind(const EHEntry *aEntry, const void *stackBasePtr) { - // The unwinding program cannot set SP to less than the initial value. - uint32_t stackLimit = mRegs[R_SP] - 4; - uint32_t stackBase = reinterpret_cast<uint32_t>(stackBasePtr); - EHInterp interp(*this, aEntry, stackLimit, stackBase); - return interp.unwind(); -} - -bool EHInterp::unwind() { - mState[R_PC] = 0; - checkStack(); - while (!mFailed) { - uint8_t insn = next(); -#if DEBUG_EHABI_UNWIND - LOGF("unwind insn = %02x", (unsigned)insn); -#endif - // Try to put the common cases first. - - // 00xxxxxx: vsp = vsp + (xxxxxx << 2) + 4 - // 01xxxxxx: vsp = vsp - (xxxxxx << 2) - 4 - if ((insn & M_ADDSP) == I_ADDSP) { - uint32_t offset = ((insn & 0x3f) << 2) + 4; - if (insn & 0x40) { - vSP() -= offset; - checkStackLimit(); - } else { - vSP() += offset; - checkStackBase(); - } - continue; - } - - // 10100nnn: Pop r4-r[4+nnn] - // 10101nnn: Pop r4-r[4+nnn], r14 - if ((insn & M_POPN) == I_POPN) { - uint8_t n = (insn & 0x07) + 1; - bool lr = insn & 0x08; - uint32_t *ptr = ptrSP(); - vSP() += (n + (lr ? 1 : 0)) * 4; - checkStackBase(); - for (uint8_t r = 4; r < 4 + n; ++r) - mState[r] = *ptr++; - if (lr) - mState[R_LR] = *ptr++; - continue; - } - - // 1011000: Finish - if (insn == I_FINISH) { - if (mState[R_PC] == 0) { - mState[R_PC] = mState[R_LR]; - // Non-standard change (bug 916106): Prevent the caller from - // re-using LR. Since the caller is by definition not a leaf - // routine, it will have to restore LR from somewhere to - // return to its own caller, so we can safely zero it here. - // This makes a difference only if an error in unwinding - // (e.g., caused by starting from within a prologue/epilogue) - // causes us to load a pointer to a leaf routine as LR; if we - // don't do something, we'll go into an infinite loop of - // "returning" to that same function. - mState[R_LR] = 0; - } - return true; - } - - // 1001nnnn: Set vsp = r[nnnn] - if ((insn & M_MOVSP) == I_MOVSP) { - vSP() = mState[insn & 0x0f]; - checkStack(); - continue; - } - - // 11001000 sssscccc: Pop VFP regs D[16+ssss]-D[16+ssss+cccc] (as FLDMFDD) - // 11001001 sssscccc: Pop VFP regs D[ssss]-D[ssss+cccc] (as FLDMFDD) - if ((insn & M_POPFDD) == I_POPFDD) { - uint8_t n = (next() & 0x0f) + 1; - // Note: if the 16+ssss+cccc > 31, the encoding is reserved. - // As the space is currently unused, we don't try to check. - vSP() += 8 * n; - checkStackBase(); - continue; - } - - // 11010nnn: Pop VFP regs D[8]-D[8+nnn] (as FLDMFDD) - if ((insn & M_POPFDD8) == I_POPFDD8) { - uint8_t n = (insn & 0x07) + 1; - vSP() += 8 * n; - checkStackBase(); - continue; - } - - // 10110010 uleb128: vsp = vsp + 0x204 + (uleb128 << 2) - if (insn == I_ADDSPBIG) { - uint32_t acc = 0; - uint8_t shift = 0; - uint8_t byte; - do { - if (shift >= 32) - return false; - byte = next(); - acc |= (byte & 0x7f) << shift; - shift += 7; - } while (byte & 0x80); - uint32_t offset = 0x204 + (acc << 2); - // The calculations above could have overflowed. - // But the one we care about is this: - if (vSP() + offset < vSP()) - mFailed = true; - vSP() += offset; - // ...so that this is the only other check needed: - checkStackBase(); - continue; - } - - // 1000iiii iiiiiiii (i not all 0): Pop under masks {r15-r12}, {r11-r4} - if ((insn & M_POPMASK) == I_POPMASK) { - popRange(4, 15, ((insn & 0x0f) << 8) | next()); - continue; - } - - // 1011001 0000iiii (i not all 0): Pop under mask {r3-r0} - if (insn == I_POPLO) { - popRange(0, 3, next() & 0x0f); - continue; - } - - // 10110011 sssscccc: Pop VFP regs D[ssss]-D[ssss+cccc] (as FLDMFDX) - if (insn == I_POPFDX) { - uint8_t n = (next() & 0x0f) + 1; - vSP() += 8 * n + 4; - checkStackBase(); - continue; - } - - // 10111nnn: Pop VFP regs D[8]-D[8+nnn] (as FLDMFDX) - if ((insn & M_POPFDX8) == I_POPFDX8) { - uint8_t n = (insn & 0x07) + 1; - vSP() += 8 * n + 4; - checkStackBase(); - continue; - } - - // unhandled instruction -#ifdef DEBUG_EHABI_UNWIND - LOGF("Unhandled EHABI instruction 0x%02x", insn); -#endif - mFailed = true; - } - return false; -} - - -bool operator<(const EHTable &lhs, const EHTable &rhs) { - return lhs.startPC() < rhs.startPC(); -} - -// Async signal unsafe. -EHAddrSpace::EHAddrSpace(const std::vector<EHTable>& aTables) - : mTables(aTables) -{ - std::sort(mTables.begin(), mTables.end()); - DebugOnly<uint32_t> lastEnd = 0; - for (std::vector<EHTable>::iterator i = mTables.begin(); - i != mTables.end(); ++i) { - MOZ_ASSERT(i->startPC() >= lastEnd); - mStarts.push_back(i->startPC()); - lastEnd = i->endPC(); - } -} - -const EHTable *EHAddrSpace::lookup(uint32_t aPC) const { - ptrdiff_t i = (std::upper_bound(mStarts.begin(), mStarts.end(), aPC) - - mStarts.begin()) - 1; - - if (i < 0 || aPC >= mTables[i].endPC()) - return 0; - return &mTables[i]; -} - - -const EHEntry *EHTable::lookup(uint32_t aPC) const { - MOZ_ASSERT(aPC >= mStartPC); - if (aPC >= mEndPC) - return nullptr; - - EntryIterator begin = entriesBegin(); - EntryIterator end = entriesEnd(); - MOZ_ASSERT(begin < end); - if (aPC < reinterpret_cast<uint32_t>(entryGet(begin)->startPC.compute())) - return nullptr; - - while (end - begin > 1) { -#ifdef EHABI_UNWIND_MORE_ASSERTS - if (entryGet(end - 1)->startPC.compute() - < entryGet(begin)->startPC.compute()) { - MOZ_CRASH("unsorted exidx"); - } -#endif - EntryIterator mid = begin + (end - begin) / 2; - if (aPC < reinterpret_cast<uint32_t>(entryGet(mid)->startPC.compute())) - end = mid; - else - begin = mid; - } - return entryGet(begin); -} - - -#if MOZ_LITTLE_ENDIAN -static const unsigned char hostEndian = ELFDATA2LSB; -#elif MOZ_BIG_ENDIAN -static const unsigned char hostEndian = ELFDATA2MSB; -#else -#error "No endian?" -#endif - -// Async signal unsafe: std::vector::reserve, std::string copy ctor. -EHTable::EHTable(const void *aELF, size_t aSize, const std::string &aName) - : mStartPC(~0), // largest uint32_t - mEndPC(0), -#ifndef HAVE_UNSORTED_EXIDX - mEntriesBegin(nullptr), - mEntriesEnd(nullptr), -#endif - mName(aName) -{ - const uint32_t base = reinterpret_cast<uint32_t>(aELF); - - if (aSize < sizeof(Elf32_Ehdr)) - return; - - const Elf32_Ehdr &file = *(reinterpret_cast<Elf32_Ehdr *>(base)); - if (memcmp(&file.e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 || - file.e_ident[EI_CLASS] != ELFCLASS32 || - file.e_ident[EI_DATA] != hostEndian || - file.e_ident[EI_VERSION] != EV_CURRENT || - file.e_ident[EI_OSABI] != ELFOSABI_SYSV || -#ifdef EI_ABIVERSION - file.e_ident[EI_ABIVERSION] != 0 || -#endif - file.e_machine != EM_ARM || - file.e_version != EV_CURRENT) - // e_flags? - return; - - MOZ_ASSERT(file.e_phoff + file.e_phnum * file.e_phentsize <= aSize); - const Elf32_Phdr *exidxHdr = 0, *zeroHdr = 0; - for (unsigned i = 0; i < file.e_phnum; ++i) { - const Elf32_Phdr &phdr = - *(reinterpret_cast<Elf32_Phdr *>(base + file.e_phoff - + i * file.e_phentsize)); - if (phdr.p_type == PT_ARM_EXIDX) { - exidxHdr = &phdr; - } else if (phdr.p_type == PT_LOAD) { - if (phdr.p_offset == 0) { - zeroHdr = &phdr; - } - if (phdr.p_flags & PF_X) { - mStartPC = std::min(mStartPC, phdr.p_vaddr); - mEndPC = std::max(mEndPC, phdr.p_vaddr + phdr.p_memsz); - } - } - } - if (!exidxHdr) - return; - if (!zeroHdr) - return; - mLoadOffset = base - zeroHdr->p_vaddr; - mStartPC += mLoadOffset; - mEndPC += mLoadOffset; - - // Create a sorted index of the index to work around linker bugs. - const EHEntry *startTable = - reinterpret_cast<const EHEntry *>(mLoadOffset + exidxHdr->p_vaddr); - const EHEntry *endTable = - reinterpret_cast<const EHEntry *>(mLoadOffset + exidxHdr->p_vaddr - + exidxHdr->p_memsz); -#ifdef HAVE_UNSORTED_EXIDX - mEntries.reserve(endTable - startTable); - for (const EHEntry *i = startTable; i < endTable; ++i) - mEntries.push_back(i); - std::sort(mEntries.begin(), mEntries.end()); -#else - mEntriesBegin = startTable; - mEntriesEnd = endTable; -#endif -} - - -mozilla::Atomic<const EHAddrSpace*> EHAddrSpace::sCurrent(nullptr); - -// Async signal safe; can fail if Update() hasn't returned yet. -const EHAddrSpace *EHAddrSpace::Get() { - return sCurrent; -} - -// Collect unwinding information from loaded objects. Calls after the -// first have no effect. Async signal unsafe. -void EHAddrSpace::Update() { - const EHAddrSpace *space = sCurrent; - if (space) - return; - - SharedLibraryInfo info = SharedLibraryInfo::GetInfoForSelf(); - std::vector<EHTable> tables; - - for (size_t i = 0; i < info.GetSize(); ++i) { - const SharedLibrary &lib = info.GetEntry(i); - if (lib.GetOffset() != 0) - // TODO: if it has a name, and we haven't seen a mapping of - // offset 0 for that file, try opening it and reading the - // headers instead. The only thing I've seen so far that's - // linked so as to need that treatment is the dynamic linker - // itself. - continue; - EHTable tab(reinterpret_cast<const void *>(lib.GetStart()), - lib.GetEnd() - lib.GetStart(), lib.GetName()); - if (tab.isValid()) - tables.push_back(tab); - } - space = new EHAddrSpace(tables); - - if (!sCurrent.compareExchange(nullptr, space)) { - delete space; - space = sCurrent; - } -} - - -EHState::EHState(const mcontext_t &context) { -#ifdef linux - mRegs[0] = context.arm_r0; - mRegs[1] = context.arm_r1; - mRegs[2] = context.arm_r2; - mRegs[3] = context.arm_r3; - mRegs[4] = context.arm_r4; - mRegs[5] = context.arm_r5; - mRegs[6] = context.arm_r6; - mRegs[7] = context.arm_r7; - mRegs[8] = context.arm_r8; - mRegs[9] = context.arm_r9; - mRegs[10] = context.arm_r10; - mRegs[11] = context.arm_fp; - mRegs[12] = context.arm_ip; - mRegs[13] = context.arm_sp; - mRegs[14] = context.arm_lr; - mRegs[15] = context.arm_pc; -#else -# error "Unhandled OS for ARM EHABI unwinding" -#endif -} - -} // namespace mozilla - |