mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-12-07 05:15:09 +00:00
267 lines
8.9 KiB
C++
267 lines
8.9 KiB
C++
/* -*- 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 "LulPlatformMacros.h"
|
|
|
|
#include <vector>
|
|
|
|
#include "mozilla/Assertions.h"
|
|
|
|
// 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 {
|
|
|
|
////////////////////////////////////////////////////////////////
|
|
// 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(LUL_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(LUL_ARCH_x64)
|
|
// 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(LUL_ARCH_x86)
|
|
DW_REG_INTEL_XBP = 5,
|
|
DW_REG_INTEL_XSP = 4,
|
|
DW_REG_INTEL_XIP = 8,
|
|
#else
|
|
# error "Unknown arch"
|
|
#endif
|
|
};
|
|
|
|
|
|
////////////////////////////////////////////////////////////////
|
|
// LExpr //
|
|
////////////////////////////////////////////////////////////////
|
|
|
|
// An expression -- very primitive. Denotes either "register +
|
|
// offset" or a dereferenced version of the same. 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.
|
|
|
|
struct LExpr {
|
|
// Denotes an expression with no value.
|
|
LExpr()
|
|
: mHow(UNKNOWN)
|
|
, mReg(0)
|
|
, mOffset(0)
|
|
{}
|
|
|
|
// Denotes any expressible expression.
|
|
LExpr(uint8_t how, int16_t reg, int32_t offset)
|
|
: mHow(how)
|
|
, mReg(reg)
|
|
, mOffset(offset)
|
|
{}
|
|
|
|
// 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
|
|
}
|
|
|
|
// 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.
|
|
|
|
enum { UNKNOWN=0, // This LExpr denotes no value.
|
|
NODEREF, // Value is (mReg + mOffset).
|
|
DEREF }; // Value is *(mReg + mOffset).
|
|
|
|
uint8_t mHow; // UNKNOWN, NODEREF or DEREF
|
|
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*));
|
|
|
|
// 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(LUL_ARCH_x64) || defined(LUL_ARCH_x86)
|
|
LExpr mXipExpr; // return address
|
|
LExpr mXspExpr;
|
|
LExpr mXbpExpr;
|
|
#elif defined(LUL_ARCH_arm)
|
|
LExpr mR15expr; // return address
|
|
LExpr mR14expr;
|
|
LExpr mR13expr;
|
|
LExpr mR12expr;
|
|
LExpr mR11expr;
|
|
LExpr mR7expr;
|
|
#else
|
|
# error "Unknown arch"
|
|
#endif
|
|
};
|
|
|
|
|
|
////////////////////////////////////////////////////////////////
|
|
// 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(RuleSet* rs);
|
|
|
|
// 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(); }
|
|
|
|
// 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()).
|
|
std::vector<RuleSet> mRuleSets;
|
|
|
|
// A logging sink, for debugging.
|
|
void (*mLog)(const char*);
|
|
};
|
|
|
|
} // namespace lul
|
|
|
|
#endif // ndef LulMainInt_h
|