Backed out changeset a95360977f76 (bug 1428453) for arm build bustage

js/src/jit/MacroAssembler.cpp

@@ -3292,34 +3292,47 @@ MacroAssembler::wasmEmitOldTrapOutOfLineCode()
           }
         }
 
-        MOZ_ASSERT(site.trap != wasm::Trap::IndirectCallBadSig);
+        if (site.trap == wasm::Trap::IndirectCallBadSig) {
+            // The indirect call bad-signature trap is a special case for two
+            // reasons:
+            //  - the check happens in the very first instructions of the
+            //    prologue, before the stack frame has been set up which messes
+            //    up everything (stack depth computations, unwinding)
+            //  - the check happens in the callee while the trap should be
+            //    reported at the caller's call_indirect
+            // To solve both problems at once, the out-of-line path (far) jumps
+            // directly to the trap exit stub. This takes advantage of the fact
+            // that there is already a CallSite for call_indirect and the
+            // current pre-prologue stack/register state.
+            append(wasm::OldTrapFarJump(site.trap, farJumpWithPatch()));
+        } else {
+            // Inherit the frame depth of the trap site. This value is captured
+            // by the wasm::CallSite to allow unwinding this frame.
+            setFramePushed(site.framePushed);
 
-        // Inherit the frame depth of the trap site. This value is captured
-        // by the wasm::CallSite to allow unwinding this frame.
-        setFramePushed(site.framePushed);
+            // Align the stack for a nullary call.
+            size_t alreadyPushed = sizeof(wasm::Frame) + framePushed();
+            size_t toPush = ABIArgGenerator().stackBytesConsumedSoFar();
+            if (size_t dec = StackDecrementForCall(ABIStackAlignment, alreadyPushed, toPush))
+                reserveStack(dec);
 
-        // Align the stack for a nullary call.
-        size_t alreadyPushed = sizeof(wasm::Frame) + framePushed();
-        size_t toPush = ABIArgGenerator().stackBytesConsumedSoFar();
-        if (size_t dec = StackDecrementForCall(ABIStackAlignment, alreadyPushed, toPush))
-            reserveStack(dec);
+            // To call the trap handler function, we must have the WasmTlsReg
+            // filled since this is the normal calling ABI. To avoid requiring
+            // every trapping operation to have the TLS register filled for the
+            // rare case that it takes a trap, we restore it from the frame on
+            // the out-of-line path. However, there are millions of out-of-line
+            // paths (viz. for loads/stores), so the load is factored out into
+            // the shared FarJumpIsland generated by patchCallSites.
 
-        // To call the trap handler function, we must have the WasmTlsReg
-        // filled since this is the normal calling ABI. To avoid requiring
-        // every trapping operation to have the TLS register filled for the
-        // rare case that it takes a trap, we restore it from the frame on
-        // the out-of-line path. However, there are millions of out-of-line
-        // paths (viz. for loads/stores), so the load is factored out into
-        // the shared FarJumpIsland generated by patchCallSites.
-
-        // Call the trap's exit, using the bytecode offset of the trap site.
-        // Note that this code is inside the same CodeRange::Function as the
-        // trap site so it's as if the trapping instruction called the
-        // trap-handling function. The frame iterator knows to skip the trap
-        // exit's frame so that unwinding begins at the frame and offset of
-        // the trapping instruction.
-        wasm::CallSiteDesc desc(site.offset, wasm::CallSiteDesc::OldTrapExit);
-        call(desc, site.trap);
+            // Call the trap's exit, using the bytecode offset of the trap site.
+            // Note that this code is inside the same CodeRange::Function as the
+            // trap site so it's as if the trapping instruction called the
+            // trap-handling function. The frame iterator knows to skip the trap
+            // exit's frame so that unwinding begins at the frame and offset of
+            // the trapping instruction.
+            wasm::CallSiteDesc desc(site.offset, wasm::CallSiteDesc::OldTrapExit);
+            call(desc, site.trap);
+        }
 
 #ifdef DEBUG
         // Traps do not return, so no need to freeStack().

js/src/jit/arm/Simulator-arm.cpp

@@ -1646,12 +1646,7 @@ Simulator::handleWasmSegFault(int32_t addr, unsigned numBytes)
     const wasm::ModuleSegment* moduleSegment = segment->asModule();
 
     wasm::Instance* instance = wasm::LookupFaultingInstance(*moduleSegment, pc, fp);
-    if (!instance)
-        return false;
-
-    MOZ_RELEASE_ASSERT(&instance->code() == &codeSegment.code());
-
-    if (!instance->memoryAccessInGuardRegion((uint8_t*)addr, numBytes))
+    if (!instance || !instance->memoryAccessInGuardRegion((uint8_t*)addr, numBytes))
         return false;
 
     const wasm::MemoryAccess* memoryAccess = instance->code().lookupMemoryAccess(pc);

js/src/vm/Stack.cpp

@@ -1823,27 +1823,13 @@ jit::JitActivation::wasmInterruptResumePC() const
 }
 
 void
-jit::JitActivation::startWasmTrap(wasm::Trap trap, uint32_t bytecodeOffset,
-                                  const wasm::RegisterState& state)
+jit::JitActivation::startWasmTrap(wasm::Trap trap, uint32_t bytecodeOffset, void* pc, void* fp)
 {
-    bool unwound;
-    wasm::UnwindState unwindState;
-    MOZ_ALWAYS_TRUE(wasm::StartUnwinding(state, &unwindState, &unwound));
-    MOZ_ASSERT(unwound == (trap == wasm::Trap::IndirectCallBadSig));
-
-    void* pc = unwindState.pc;
-    wasm::Frame* fp = unwindState.fp;
-
-    const wasm::Code& code = fp->tls->instance->code();
-    MOZ_RELEASE_ASSERT(&code == wasm::LookupCode(pc));
-
-    // If the frame was unwound, the bytecodeOffset must be recovered from the
-    // callsite so that it is accurate.
-    if (unwound)
-        bytecodeOffset = code.lookupCallSite(pc)->lineOrBytecode();
+    MOZ_ASSERT(pc);
+    MOZ_ASSERT(fp);
 
     cx_->runtime()->wasmUnwindData.ref().construct<wasm::TrapData>(pc, trap, bytecodeOffset);
-    setWasmExitFP(fp);
+    setWasmExitFP((wasm::Frame*)fp);
 }
 
 void

js/src/vm/Stack.h

@@ -1667,13 +1667,13 @@ class JitActivation : public Activation
     // when the interrupt is handled.
 
     // Returns true iff we've entered interrupted state.
-    bool startWasmInterrupt(const wasm::RegisterState& state);
+    bool startWasmInterrupt(const JS::ProfilingFrameIterator::RegisterState& state);
     void finishWasmInterrupt();
     bool isWasmInterrupted() const;
     void* wasmInterruptUnwindPC() const;
     void* wasmInterruptResumePC() const;
 
-    void startWasmTrap(wasm::Trap trap, uint32_t bytecodeOffset, const wasm::RegisterState& state);
+    void startWasmTrap(wasm::Trap trap, uint32_t bytecodeOffset, void* pc, void* fp);
     void finishWasmTrap();
     bool isWasmTrapping() const;
     void* wasmTrapPC() const;

js/src/wasm/WasmFrameIter.cpp

@@ -459,26 +459,18 @@ wasm::GenerateFunctionPrologue(MacroAssembler& masm, uint32_t framePushed, IsLea
     masm.flushBuffer();
     masm.haltingAlign(CodeAlignment);
 
-    // The table entry falls through into the normal entry after it has checked
-    // the signature.
-    Label normalEntry;
-
-    // Generate table entry. The BytecodeOffset of the trap is fixed up to be
-    // the bytecode offset of the callsite by JitActivation::startWasmTrap.
+    // Generate table entry:
     offsets->begin = masm.currentOffset();
+    OldTrapDesc trap(trapOffset, Trap::IndirectCallBadSig, 0);
     switch (sigId.kind()) {
       case SigIdDesc::Kind::Global: {
         Register scratch = WasmTableCallScratchReg;
         masm.loadWasmGlobalPtr(sigId.globalDataOffset(), scratch);
-        masm.branchPtr(Assembler::Condition::Equal, WasmTableCallSigReg, scratch,
-                       &normalEntry);
-        masm.wasmTrap(Trap::IndirectCallBadSig, BytecodeOffset(0));
+        masm.branchPtr(Assembler::Condition::NotEqual, WasmTableCallSigReg, scratch, trap);
         break;
       }
       case SigIdDesc::Kind::Immediate: {
-        masm.branch32(Assembler::Condition::Equal, WasmTableCallSigReg, Imm32(sigId.immediate()),
-                      &normalEntry);
-        masm.wasmTrap(Trap::IndirectCallBadSig, BytecodeOffset(0));
+        masm.branch32(Assembler::Condition::NotEqual, WasmTableCallSigReg, Imm32(sigId.immediate()), trap);
         break;
       }
       case SigIdDesc::Kind::None:
@@ -491,7 +483,6 @@ wasm::GenerateFunctionPrologue(MacroAssembler& masm, uint32_t framePushed, IsLea
 
     // Generate normal entry:
     masm.nopAlign(CodeAlignment);
-    masm.bind(&normalEntry);
     GenerateCallablePrologue(masm, &offsets->normalEntry);
 
     // Tiering works as follows.  The Code owns a jumpTable, which has one
@@ -1281,21 +1272,20 @@ wasm::LookupFaultingInstance(const ModuleSegment& codeSegment, void* pc, void* f
         return nullptr;
 
     size_t offsetInModule = ((uint8_t*)pc) - codeSegment.base();
-    if ((offsetInModule >= codeRange->funcNormalEntry() &&
-         offsetInModule < codeRange->funcNormalEntry() + SetFP) ||
-        (offsetInModule >= codeRange->ret() - PoppedFP &&
-         offsetInModule <= codeRange->ret()))
-    {
+    if (offsetInModule < codeRange->funcNormalEntry() + SetFP)
+        return nullptr;
+    if (offsetInModule >= codeRange->ret() - PoppedFP && offsetInModule <= codeRange->ret())
         return nullptr;
-    }
 
     Instance* instance = reinterpret_cast<Frame*>(fp)->tls->instance;
 
-    // TODO: In the special case of a cross-instance indirect call bad-signature
-    // fault, fp can point to the caller frame which is in a different
-    // instance/module than pc. This special case should go away when old-style
-    // traps go away and signal handling is reworked.
+    // TODO: when Trap::IndirectCallBadSig is converted away from being an
+    // OldTrap, this could become a release assert again. The reason for the
+    // check is the out-of-line trap stub for the table entry's signature check,
+    // which executes before fp has been updated.
     //MOZ_RELEASE_ASSERT(&instance->code() == &codeSegment.code());
+    if (&instance->code() != &codeSegment.code())
+        return nullptr;
 
     return instance;
 }

js/src/wasm/WasmSignalHandlers.cpp

@@ -1039,13 +1039,11 @@ HandleFault(PEXCEPTION_POINTERS exception)
         if (!moduleSegment->code().lookupTrap(pc, &trap, &bytecode))
             return false;
 
-        activation->startWasmTrap(trap, bytecode.offset, ToRegisterState(context));
+        activation->startWasmTrap(trap, bytecode.offset, pc, ContextToFP(context));
         *ppc = moduleSegment->trapCode();
         return true;
     }
 
-    MOZ_RELEASE_ASSERT(&instance->code() == &moduleSegment->code());
-
     if (record->NumberParameters < 2)
         return false;
 
@@ -1172,11 +1170,9 @@ HandleMachException(JSContext* cx, const ExceptionRequest& request)
         if (!moduleSegment->code().lookupTrap(pc, &trap, &bytecode))
             return false;
 
-        activation->startWasmTrap(trap, bytecode.offset, ToRegisterState(&context));
+        activation->startWasmTrap(trap, bytecode.offset, pc, ContextToFP(&context));
         *ppc = moduleSegment->trapCode();
     } else {
-        MOZ_RELEASE_ASSERT(&instance->code() == &moduleSegment->code());
-
         MOZ_ASSERT(request.body.exception == EXC_BAD_ACCESS);
         if (request.body.codeCnt != 2)
             return false;
@@ -1398,13 +1394,11 @@ HandleFault(int signum, siginfo_t* info, void* ctx)
         if (!moduleSegment->code().lookupTrap(pc, &trap, &bytecode))
             return false;
 
-        activation->startWasmTrap(trap, bytecode.offset, ToRegisterState(context));
+        activation->startWasmTrap(trap, bytecode.offset, pc, ContextToFP(context));
         *ppc = moduleSegment->trapCode();
         return true;
     }
 
-    MOZ_RELEASE_ASSERT(&instance->code() == &moduleSegment->code());
-
     uint8_t* faultingAddress = reinterpret_cast<uint8_t*>(info->si_addr);
 
     // Although it's not strictly necessary, to make sure we're not covering up

js/src/wasm/WasmStubs.cpp

@@ -1730,14 +1730,14 @@ wasm::GenerateStubs(const ModuleEnvironment& env, const FuncImportVector& import
           case Trap::InvalidConversionToInteger:
           case Trap::IntegerDivideByZero:
           case Trap::IndirectCallToNull:
-          case Trap::IndirectCallBadSig:
           case Trap::ImpreciseSimdConversion:
           case Trap::StackOverflow:
           case Trap::ThrowReported:
             break;
           // The TODO list of "old" traps to convert to new traps:
           case Trap::OutOfBounds:
-          case Trap::UnalignedAccess: {
+          case Trap::UnalignedAccess:
+          case Trap::IndirectCallBadSig: {
             CallableOffsets offsets;
             if (!GenerateOldTrapExit(masm, trap, &throwLabel, &offsets))
                 return false;