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| -rw-r--r-- | mozglue/baseprofiler/lul/LulMainInt.h | 420 |
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diff --git a/mozglue/baseprofiler/lul/LulMainInt.h b/mozglue/baseprofiler/lul/LulMainInt.h new file mode 100644 index 0000000000..c2ee45d73d --- /dev/null +++ b/mozglue/baseprofiler/lul/LulMainInt.h @@ -0,0 +1,420 @@ +/* -*- 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/. */ + +#ifndef LulMainInt_h +#define LulMainInt_h + +#include "PlatformMacros.h" +#include "LulMain.h" // for TaggedUWord + +#include "mozilla/Assertions.h" + +#include <string> +#include <vector> + +// This file is provides internal interface inside LUL. If you are an +// end-user of LUL, do not include it in your code. The end-user +// interface is in LulMain.h. + +namespace lul { + +using std::vector; + +//////////////////////////////////////////////////////////////// +// DW_REG_ constants // +//////////////////////////////////////////////////////////////// + +// These are the Dwarf CFI register numbers, as (presumably) defined +// in the ELF ABI supplements for each architecture. + +enum DW_REG_NUMBER { + // No real register has this number. It's convenient to be able to + // treat the CFA (Canonical Frame Address) as "just another + // register", though. + DW_REG_CFA = -1, +#if defined(GP_ARCH_arm) + // ARM registers + DW_REG_ARM_R7 = 7, + DW_REG_ARM_R11 = 11, + DW_REG_ARM_R12 = 12, + DW_REG_ARM_R13 = 13, + DW_REG_ARM_R14 = 14, + DW_REG_ARM_R15 = 15, +#elif defined(GP_ARCH_arm64) + // aarch64 registers + DW_REG_AARCH64_X29 = 29, + DW_REG_AARCH64_X30 = 30, + DW_REG_AARCH64_SP = 31, +#elif defined(GP_ARCH_amd64) + // Because the X86 (32 bit) and AMD64 (64 bit) summarisers are + // combined, a merged set of register constants is needed. + DW_REG_INTEL_XBP = 6, + DW_REG_INTEL_XSP = 7, + DW_REG_INTEL_XIP = 16, +#elif defined(GP_ARCH_x86) + DW_REG_INTEL_XBP = 5, + DW_REG_INTEL_XSP = 4, + DW_REG_INTEL_XIP = 8, +#elif defined(GP_ARCH_mips64) + DW_REG_MIPS_SP = 29, + DW_REG_MIPS_FP = 30, + DW_REG_MIPS_PC = 34, +#else +# error "Unknown arch" +#endif +}; + +//////////////////////////////////////////////////////////////// +// PfxExpr // +//////////////////////////////////////////////////////////////// + +enum PfxExprOp { + // meaning of mOperand effect on stack + PX_Start, // bool start-with-CFA? start, with CFA on stack, or not + PX_End, // none stop; result is at top of stack + PX_SImm32, // int32 push signed int32 + PX_DwReg, // DW_REG_NUMBER push value of the specified reg + PX_Deref, // none pop X ; push *X + PX_Add, // none pop X ; pop Y ; push Y + X + PX_Sub, // none pop X ; pop Y ; push Y - X + PX_And, // none pop X ; pop Y ; push Y & X + PX_Or, // none pop X ; pop Y ; push Y | X + PX_CmpGES, // none pop X ; pop Y ; push (Y >=s X) ? 1 : 0 + PX_Shl // none pop X ; pop Y ; push Y << X +}; + +struct PfxInstr { + PfxInstr(PfxExprOp opcode, int32_t operand) + : mOpcode(opcode), mOperand(operand) {} + explicit PfxInstr(PfxExprOp opcode) : mOpcode(opcode), mOperand(0) {} + bool operator==(const PfxInstr& other) const { + return mOpcode == other.mOpcode && mOperand == other.mOperand; + } + PfxExprOp mOpcode; + int32_t mOperand; +}; + +static_assert(sizeof(PfxInstr) <= 8, "PfxInstr size changed unexpectedly"); + +// Evaluate the prefix expression whose PfxInstrs start at aPfxInstrs[start]. +// In the case of any mishap (stack over/underflow, running off the end of +// the instruction vector, obviously malformed sequences), +// return an invalid TaggedUWord. +// RUNS IN NO-MALLOC CONTEXT +TaggedUWord EvaluatePfxExpr(int32_t start, const UnwindRegs* aOldRegs, + TaggedUWord aCFA, const StackImage* aStackImg, + const vector<PfxInstr>& aPfxInstrs); + +//////////////////////////////////////////////////////////////// +// LExpr // +//////////////////////////////////////////////////////////////// + +// An expression -- very primitive. Denotes either "register + +// offset", a dereferenced version of the same, or a reference to a +// prefix expression stored elsewhere. So as to allow convenient +// handling of Dwarf-derived unwind info, the register may also denote +// the CFA. A large number of these need to be stored, so we ensure +// it fits into 8 bytes. See comment below on RuleSet to see how +// expressions fit into the bigger picture. + +enum LExprHow { + UNKNOWN = 0, // This LExpr denotes no value. + NODEREF, // Value is (mReg + mOffset). + DEREF, // Value is *(mReg + mOffset). + PFXEXPR // Value is EvaluatePfxExpr(secMap->mPfxInstrs[mOffset]) +}; + +inline static const char* NameOf_LExprHow(LExprHow how) { + switch (how) { + case UNKNOWN: + return "UNKNOWN"; + case NODEREF: + return "NODEREF"; + case DEREF: + return "DEREF"; + case PFXEXPR: + return "PFXEXPR"; + default: + return "LExpr-??"; + } +} + +struct LExpr { + // Denotes an expression with no value. + LExpr() : mHow(UNKNOWN), mReg(0), mOffset(0) {} + + // Denotes any expressible expression. + LExpr(LExprHow how, int16_t reg, int32_t offset) + : mHow(how), mReg(reg), mOffset(offset) { + switch (how) { + case UNKNOWN: + MOZ_ASSERT(reg == 0 && offset == 0); + break; + case NODEREF: + break; + case DEREF: + break; + case PFXEXPR: + MOZ_ASSERT(reg == 0 && offset >= 0); + break; + default: + MOZ_ASSERT(0, "LExpr::LExpr: invalid how"); + } + } + + // Change the offset for an expression that references memory. + LExpr add_delta(long delta) { + MOZ_ASSERT(mHow == NODEREF); + // If this is a non-debug build and the above assertion would have + // failed, at least return LExpr() so that the machinery that uses + // the resulting expression fails in a repeatable way. + return (mHow == NODEREF) ? LExpr(mHow, mReg, mOffset + delta) + : LExpr(); // Gone bad + } + + // Dereference an expression that denotes a memory address. + LExpr deref() { + MOZ_ASSERT(mHow == NODEREF); + // Same rationale as for add_delta(). + return (mHow == NODEREF) ? LExpr(DEREF, mReg, mOffset) + : LExpr(); // Gone bad + } + + // Print a rule for recovery of |aNewReg| whose recovered value + // is this LExpr. + std::string ShowRule(const char* aNewReg) const; + + // Evaluate this expression, producing a TaggedUWord. |aOldRegs| + // holds register values that may be referred to by the expression. + // |aCFA| holds the CFA value, if any, that applies. |aStackImg| + // contains a chuck of stack that will be consulted if the expression + // references memory. |aPfxInstrs| holds the vector of PfxInstrs + // that will be consulted if this is a PFXEXPR. + // RUNS IN NO-MALLOC CONTEXT + TaggedUWord EvaluateExpr(const UnwindRegs* aOldRegs, TaggedUWord aCFA, + const StackImage* aStackImg, + const vector<PfxInstr>* aPfxInstrs) const; + + // Representation of expressions. If |mReg| is DW_REG_CFA (-1) then + // it denotes the CFA. All other allowed values for |mReg| are + // nonnegative and are DW_REG_ values. + LExprHow mHow : 8; + int16_t mReg; // A DW_REG_ value + int32_t mOffset; // 32-bit signed offset should be more than enough. +}; + +static_assert(sizeof(LExpr) <= 8, "LExpr size changed unexpectedly"); + +//////////////////////////////////////////////////////////////// +// RuleSet // +//////////////////////////////////////////////////////////////// + +// This is platform-dependent. For some address range, describes how +// to recover the CFA and then how to recover the registers for the +// previous frame. +// +// The set of LExprs contained in a given RuleSet describe a DAG which +// says how to compute the caller's registers ("new registers") from +// the callee's registers ("old registers"). The DAG can contain a +// single internal node, which is the value of the CFA for the callee. +// It would be possible to construct a DAG that omits the CFA, but +// including it makes the summarisers simpler, and the Dwarf CFI spec +// has the CFA as a central concept. +// +// For this to make sense, |mCfaExpr| can't have +// |mReg| == DW_REG_CFA since we have no previous value for the CFA. +// All of the other |Expr| fields can -- and usually do -- specify +// |mReg| == DW_REG_CFA. +// +// With that in place, the unwind algorithm proceeds as follows. +// +// (0) Initially: we have values for the old registers, and a memory +// image. +// +// (1) Compute the CFA by evaluating |mCfaExpr|. Add the computed +// value to the set of "old registers". +// +// (2) Compute values for the registers by evaluating all of the other +// |Expr| fields in the RuleSet. These can depend on both the old +// register values and the just-computed CFA. +// +// If we are unwinding without computing a CFA, perhaps because the +// RuleSets are derived from EXIDX instead of Dwarf, then +// |mCfaExpr.mHow| will be LExpr::UNKNOWN, so the computed value will +// be invalid -- that is, TaggedUWord() -- and so any attempt to use +// that will result in the same value. But that's OK because the +// RuleSet would make no sense if depended on the CFA but specified no +// way to compute it. +// +// A RuleSet is not allowed to cover zero address range. Having zero +// length would break binary searching in SecMaps and PriMaps. + +class RuleSet { + public: + RuleSet(); + void Print(void (*aLog)(const char*)) const; + + // Find the LExpr* for a given DW_REG_ value in this class. + LExpr* ExprForRegno(DW_REG_NUMBER aRegno); + + uintptr_t mAddr; + uintptr_t mLen; + // How to compute the CFA. + LExpr mCfaExpr; + // How to compute caller register values. These may reference the + // value defined by |mCfaExpr|. +#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86) + LExpr mXipExpr; // return address + LExpr mXspExpr; + LExpr mXbpExpr; +#elif defined(GP_ARCH_arm) + LExpr mR15expr; // return address + LExpr mR14expr; + LExpr mR13expr; + LExpr mR12expr; + LExpr mR11expr; + LExpr mR7expr; +#elif defined(GP_ARCH_arm64) + LExpr mX29expr; // frame pointer register + LExpr mX30expr; // link register + LExpr mSPexpr; +#elif defined(GP_ARCH_mips64) + LExpr mPCexpr; + LExpr mFPexpr; + LExpr mSPexpr; +#else +# error "Unknown arch" +#endif +}; + +// Returns |true| for Dwarf register numbers which are members +// of the set of registers that LUL unwinds on this target. +static inline bool registerIsTracked(DW_REG_NUMBER reg) { + switch (reg) { +#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86) + case DW_REG_INTEL_XBP: + case DW_REG_INTEL_XSP: + case DW_REG_INTEL_XIP: + return true; +#elif defined(GP_ARCH_arm) + case DW_REG_ARM_R7: + case DW_REG_ARM_R11: + case DW_REG_ARM_R12: + case DW_REG_ARM_R13: + case DW_REG_ARM_R14: + case DW_REG_ARM_R15: + return true; +#elif defined(GP_ARCH_arm64) + case DW_REG_AARCH64_X29: + case DW_REG_AARCH64_X30: + case DW_REG_AARCH64_SP: + return true; +#elif defined(GP_ARCH_mips64) + case DW_REG_MIPS_FP: + case DW_REG_MIPS_SP: + case DW_REG_MIPS_PC: + return true; +#else +# error "Unknown arch" +#endif + default: + return false; + } +} + +//////////////////////////////////////////////////////////////// +// SecMap // +//////////////////////////////////////////////////////////////// + +// A SecMap may have zero address range, temporarily, whilst RuleSets +// are being added to it. But adding a zero-range SecMap to a PriMap +// will make it impossible to maintain the total order of the PriMap +// entries, and so that can't be allowed to happen. + +class SecMap { + public: + // These summarise the contained mRuleSets, in that they give + // exactly the lowest and highest addresses that any of the entries + // in this SecMap cover. Hence invariants: + // + // mRuleSets is nonempty + // <=> mSummaryMinAddr <= mSummaryMaxAddr + // && mSummaryMinAddr == mRuleSets[0].mAddr + // && mSummaryMaxAddr == mRuleSets[#rulesets-1].mAddr + // + mRuleSets[#rulesets-1].mLen - 1; + // + // This requires that no RuleSet has zero length. + // + // mRuleSets is empty + // <=> mSummaryMinAddr > mSummaryMaxAddr + // + // This doesn't constrain mSummaryMinAddr and mSummaryMaxAddr uniquely, + // so let's use mSummaryMinAddr == 1 and mSummaryMaxAddr == 0 to denote + // this case. + + explicit SecMap(void (*aLog)(const char*)); + ~SecMap(); + + // Binary search mRuleSets to find one that brackets |ia|, or nullptr + // if none is found. It's not allowable to do this until PrepareRuleSets + // has been called first. + RuleSet* FindRuleSet(uintptr_t ia); + + // Add a RuleSet to the collection. The rule is copied in. Calling + // this makes the map non-searchable. + void AddRuleSet(const RuleSet* rs); + + // Add a PfxInstr to the vector of such instrs, and return the index + // in the vector. Calling this makes the map non-searchable. + uint32_t AddPfxInstr(PfxInstr pfxi); + + // Returns the entire vector of PfxInstrs. + const vector<PfxInstr>* GetPfxInstrs() { return &mPfxInstrs; } + + // Prepare the map for searching. Also, remove any rules for code + // address ranges which don't fall inside [start, +len). |len| may + // not be zero. + void PrepareRuleSets(uintptr_t start, size_t len); + + bool IsEmpty(); + + size_t Size() { return mRuleSets.size(); } + + size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const; + + // The min and max addresses of the addresses in the contained + // RuleSets. See comment above for invariants. + uintptr_t mSummaryMinAddr; + uintptr_t mSummaryMaxAddr; + + private: + // False whilst adding entries; true once it is safe to call FindRuleSet. + // Transition (false->true) is caused by calling PrepareRuleSets(). + bool mUsable; + + // A vector of RuleSets, sorted, nonoverlapping (post Prepare()). + vector<RuleSet> mRuleSets; + + // A vector of PfxInstrs, which are referred to by the RuleSets. + // These are provided as a representation of Dwarf expressions + // (DW_CFA_val_expression, DW_CFA_expression, DW_CFA_def_cfa_expression), + // are relatively expensive to evaluate, and and are therefore + // expected to be used only occasionally. + // + // The vector holds a bunch of separate PfxInstr programs, each one + // starting with a PX_Start and terminated by a PX_End, all + // concatenated together. When a RuleSet can't recover a value + // using a self-contained LExpr, it uses a PFXEXPR whose mOffset is + // the index in this vector of start of the necessary PfxInstr program. + vector<PfxInstr> mPfxInstrs; + + // A logging sink, for debugging. + void (*mLog)(const char*); +}; + +} // namespace lul + +#endif // ndef LulMainInt_h |