The Tor Browser: tools/profiler/LulDwarfSummariser.cpp@97036ab72558 (annotated)

tools/profiler/LulDwarfSummariser.cpp@97036ab72558 (annotated)

tools/profiler/LulDwarfSummariser.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

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

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tools/profiler/LulDwarfSummariser.cpp@97036ab72558 (annotated)

tools/profiler/LulDwarfSummariser.cpp