mirror of
https://github.com/mozilla/gecko-dev.git
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243 lines
7.8 KiB
C++
243 lines
7.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "LulDwarfSummariser.h"
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#include "mozilla/Assertions.h"
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// Set this to 1 for verbose logging
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#define DEBUG_SUMMARISER 0
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namespace lul {
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Summariser::Summariser(SecMap* aSecMap, uintptr_t aTextBias,
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void(*aLog)(const char*))
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: mSecMap(aSecMap)
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, mTextBias(aTextBias)
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, mLog(aLog)
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{
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mCurrAddr = 0;
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mMax1Addr = 0; // Gives an empty range.
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// Initialise the running RuleSet to "haven't got a clue" status.
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new (&mCurrRules) RuleSet();
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}
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void
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Summariser::Entry(uintptr_t aAddress, uintptr_t aLength)
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{
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aAddress += mTextBias;
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if (DEBUG_SUMMARISER) {
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char buf[100];
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snprintf(buf, sizeof(buf), "LUL Entry(%llx, %llu)\n",
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(unsigned long long int)aAddress,
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(unsigned long long int)aLength);
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buf[sizeof(buf)-1] = 0;
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mLog(buf);
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}
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// This throws away any previous summary, that is, assumes
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// that the previous summary, if any, has been properly finished
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// by a call to End().
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mCurrAddr = aAddress;
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mMax1Addr = aAddress + aLength;
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new (&mCurrRules) RuleSet();
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}
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void
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Summariser::Rule(uintptr_t aAddress,
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int aNewReg, int aOldReg, intptr_t aOffset, bool aDeref)
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{
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aAddress += mTextBias;
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if (DEBUG_SUMMARISER) {
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char buf[100];
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snprintf(buf, sizeof(buf),
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"LUL 0x%llx old-r%d = %sr%d + %ld%s\n",
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(unsigned long long int)aAddress, aNewReg,
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aDeref ? "*(" : "", aOldReg, (long)aOffset, aDeref ? ")" : "");
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buf[sizeof(buf)-1] = 0;
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mLog(buf);
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}
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if (mCurrAddr < aAddress) {
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// Flush the existing summary first.
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mCurrRules.mAddr = mCurrAddr;
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mCurrRules.mLen = aAddress - mCurrAddr;
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mSecMap->AddRuleSet(&mCurrRules);
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if (DEBUG_SUMMARISER) {
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mLog("LUL "); mCurrRules.Print(mLog);
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mLog("\n");
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}
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mCurrAddr = aAddress;
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}
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// FIXME: factor out common parts of the arch-dependent summarisers.
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#if defined(LUL_ARCH_arm)
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// ----------------- arm ----------------- //
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// Now, can we add the rule to our summary? This depends on whether
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// the registers and the overall expression are representable. This
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// is the heart of the summarisation process.
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switch (aNewReg) {
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case DW_REG_CFA:
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// This is a rule that defines the CFA. The only forms we
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// choose to represent are: r7/11/12/13 + offset. The offset
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// must fit into 32 bits since 'uintptr_t' is 32 bit on ARM,
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// hence there is no need to check it for overflow.
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if (aDeref) {
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goto cant_summarise;
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}
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switch (aOldReg) {
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case DW_REG_ARM_R7: case DW_REG_ARM_R11:
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case DW_REG_ARM_R12: case DW_REG_ARM_R13:
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break;
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default:
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goto cant_summarise;
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}
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mCurrRules.mCfaExpr = LExpr(LExpr::NODEREF, aOldReg, aOffset);
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break;
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case DW_REG_ARM_R7: case DW_REG_ARM_R11: case DW_REG_ARM_R12:
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case DW_REG_ARM_R13: case DW_REG_ARM_R14: case DW_REG_ARM_R15: {
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// Check the aOldReg is valid.
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switch (aOldReg) {
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case DW_REG_CFA:
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case DW_REG_ARM_R7: case DW_REG_ARM_R11: case DW_REG_ARM_R12:
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case DW_REG_ARM_R13: case DW_REG_ARM_R14: case DW_REG_ARM_R15:
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break;
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default:
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goto cant_summarise;
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}
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// This is a new rule for one of r{7,11,12,13,14,15} and has a
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// representable offset. In particular the new value of r15 is
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// going to be the return address.
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LExpr expr = LExpr(aDeref ? LExpr::DEREF : LExpr::NODEREF,
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aOldReg, aOffset);
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switch (aNewReg) {
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case DW_REG_ARM_R7: mCurrRules.mR7expr = expr; break;
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case DW_REG_ARM_R11: mCurrRules.mR11expr = expr; break;
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case DW_REG_ARM_R12: mCurrRules.mR12expr = expr; break;
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case DW_REG_ARM_R13: mCurrRules.mR13expr = expr; break;
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case DW_REG_ARM_R14: mCurrRules.mR14expr = expr; break;
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case DW_REG_ARM_R15: mCurrRules.mR15expr = expr; break;
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default: MOZ_ASSERT(0);
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}
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break;
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}
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default:
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goto cant_summarise;
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}
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// Mark callee-saved registers (r4 .. r11) as unchanged, if there is
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// no other information about them. FIXME: do this just once, at
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// the point where the ruleset is committed.
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if (mCurrRules.mR7expr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mR7expr = LExpr(LExpr::NODEREF, DW_REG_ARM_R7, 0);
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}
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if (mCurrRules.mR11expr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mR11expr = LExpr(LExpr::NODEREF, DW_REG_ARM_R11, 0);
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}
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if (mCurrRules.mR12expr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mR12expr = LExpr(LExpr::NODEREF, DW_REG_ARM_R12, 0);
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}
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// The old r13 (SP) value before the call is always the same as the
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// CFA.
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mCurrRules.mR13expr = LExpr(LExpr::NODEREF, DW_REG_CFA, 0);
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// If there's no information about R15 (the return address), say
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// it's a copy of R14 (the link register).
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if (mCurrRules.mR15expr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mR15expr = LExpr(LExpr::NODEREF, DW_REG_ARM_R14, 0);
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}
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#elif defined(LUL_ARCH_x64) || defined(LUL_ARCH_x86)
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// ---------------- x64/x86 ---------------- //
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// Now, can we add the rule to our summary? This depends on whether
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// the registers and the overall expression are representable. This
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// is the heart of the summarisation process. In the 64 bit case
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// we need to check that aOffset will fit into an int32_t. In the
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// 32 bit case it is expected that the compiler will fold out the
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// test since it always succeeds.
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if (aNewReg == DW_REG_CFA) {
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// This is a rule that defines the CFA. The only forms we can
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// represent are: = SP+offset or = FP+offset.
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if (!aDeref && aOffset == (intptr_t)(int32_t)aOffset &&
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(aOldReg == DW_REG_INTEL_XSP || aOldReg == DW_REG_INTEL_XBP)) {
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mCurrRules.mCfaExpr = LExpr(LExpr::NODEREF, aOldReg, aOffset);
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} else {
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goto cant_summarise;
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}
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}
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else
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if ((aNewReg == DW_REG_INTEL_XSP ||
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aNewReg == DW_REG_INTEL_XBP || aNewReg == DW_REG_INTEL_XIP) &&
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(aOldReg == DW_REG_CFA ||
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aOldReg == DW_REG_INTEL_XSP ||
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aOldReg == DW_REG_INTEL_XBP || aOldReg == DW_REG_INTEL_XIP) &&
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aOffset == (intptr_t)(int32_t)aOffset) {
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// This is a new rule for SP, BP or the return address
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// respectively, and has a representable offset.
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LExpr expr = LExpr(aDeref ? LExpr::DEREF : LExpr::NODEREF,
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aOldReg, aOffset);
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switch (aNewReg) {
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case DW_REG_INTEL_XBP: mCurrRules.mXbpExpr = expr; break;
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case DW_REG_INTEL_XSP: mCurrRules.mXspExpr = expr; break;
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case DW_REG_INTEL_XIP: mCurrRules.mXipExpr = expr; break;
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default: MOZ_CRASH("impossible value for aNewReg");
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}
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}
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else {
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goto cant_summarise;
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}
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// On Intel, it seems the old SP value before the call is always the
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// same as the CFA. Therefore, in the absence of any other way to
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// recover the SP, specify that the CFA should be copied.
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if (mCurrRules.mXspExpr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mXspExpr = LExpr(LExpr::NODEREF, DW_REG_CFA, 0);
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}
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// Also, gcc says "Undef" for BP when it is unchanged.
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if (mCurrRules.mXbpExpr.mHow == LExpr::UNKNOWN) {
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mCurrRules.mXbpExpr = LExpr(LExpr::NODEREF, DW_REG_INTEL_XBP, 0);
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}
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#else
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# error "Unsupported arch"
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#endif
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return;
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cant_summarise:
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if (0) {
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mLog("LUL can't summarise\n");
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}
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}
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void
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Summariser::End()
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{
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if (DEBUG_SUMMARISER) {
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mLog("LUL End\n");
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}
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if (mCurrAddr < mMax1Addr) {
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mCurrRules.mAddr = mCurrAddr;
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mCurrRules.mLen = mMax1Addr - mCurrAddr;
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mSecMap->AddRuleSet(&mCurrRules);
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if (DEBUG_SUMMARISER) {
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mLog("LUL "); mCurrRules.Print(mLog);
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mLog("\n");
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}
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}
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}
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} // namespace lul
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