JIT: When making memory writable, include the exception handler

makeWritable() rounds the memory down to the next page boundary. Usually
we include the exception handler this way, unless the offset from the
page boundary is less than the exception handler size. Make it explicit
that we do want the exception handler to be writable, too.

Fixes: QTBUG-89513
Pick-to: 5.15 6.0
Change-Id: I2fb8fb0e1dcc3450b036924463dc1b40d2020c46
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 18 insertions, 12 deletions

diff --git a/src/3rdparty/masm/assembler/AssemblerBuffer.h b/src/3rdparty/masm/assembler/AssemblerBuffer.h
index 45874235b6..2292a4c244 100644
--- a/src/3rdparty/masm/assembler/AssemblerBuffer.h
+++ b/src/3rdparty/masm/assembler/AssemblerBuffer.h
@@ -140,9 +140,9 @@ namespace JSC {
             if (!result)
                 return 0;
 
-            ExecutableAllocator::makeWritable(result->start(), result->sizeInBytes());
+            ExecutableAllocator::makeWritable(result->memoryStart(), result->memorySize());
 
-            memcpy(result->start(), m_buffer, m_index);
+            memcpy(result->codeStart(), m_buffer, m_index);
             
             return result.release();
         }
diff --git a/src/3rdparty/masm/assembler/LinkBuffer.h b/src/3rdparty/masm/assembler/LinkBuffer.h
index ba5a98733e..3fe5d56c47 100644
--- a/src/3rdparty/masm/assembler/LinkBuffer.h
+++ b/src/3rdparty/masm/assembler/LinkBuffer.h
@@ -333,7 +333,7 @@ inline void LinkBufferBase<MacroAssembler, ExecutableOffsetCalculator>::linkCode
     m_executableMemory = m_assembler->m_assembler.executableCopy(*m_globalData, ownerUID, effort);
     if (!m_executableMemory)
         return;
-    m_code = m_executableMemory->start();
+    m_code = m_executableMemory->codeStart();
     m_size = m_assembler->m_assembler.codeSize();
     ASSERT(m_code);
 }
@@ -355,7 +355,8 @@ void LinkBufferBase<MacroAssembler, ExecutableOffsetCalculator>::performFinaliza
 template <typename MacroAssembler, template <typename T> class ExecutableOffsetCalculator>
 inline void LinkBufferBase<MacroAssembler, ExecutableOffsetCalculator>::makeExecutable()
 {
-    ExecutableAllocator::makeExecutable(code(), static_cast<int>(m_size));
+    ExecutableAllocator::makeExecutable(m_executableMemory->memoryStart(),
+                                        m_executableMemory->memorySize());
 }
 
 template <typename MacroAssembler>
@@ -442,9 +443,9 @@ inline void BranchCompactingLinkBuffer<MacroAssembler>::linkCode(void* ownerUID,
     m_executableMemory = m_globalData->executableAllocator.allocate(*m_globalData, m_initialSize, ownerUID, effort);
     if (!m_executableMemory)
         return;
-    m_code = (uint8_t*)m_executableMemory->start();
+    m_code = (uint8_t*)m_executableMemory->codeStart();
     ASSERT(m_code);
-    ExecutableAllocator::makeWritable(m_code, m_initialSize);
+    ExecutableAllocator::makeWritable(m_executableMemory->memoryStart(), m_executableMemory->memorySize());
     uint8_t* inData = (uint8_t*)m_assembler->unlinkedCode();
     uint8_t* outData = reinterpret_cast<uint8_t*>(m_code);
     int readPtr = 0;
diff --git a/src/3rdparty/masm/assembler/MacroAssemblerCodeRef.h b/src/3rdparty/masm/assembler/MacroAssemblerCodeRef.h
index a7e78ad78f..cde9751108 100644
--- a/src/3rdparty/masm/assembler/MacroAssemblerCodeRef.h
+++ b/src/3rdparty/masm/assembler/MacroAssemblerCodeRef.h
@@ -357,11 +357,11 @@ public:
     }
 
     MacroAssemblerCodeRef(PassRefPtr<ExecutableMemoryHandle> executableMemory)
-        : m_codePtr(executableMemory->start())
+        : m_codePtr(executableMemory->codeStart())
         , m_executableMemory(executableMemory)
     {
         ASSERT(m_executableMemory->isManaged());
-        ASSERT(m_executableMemory->start());
+        ASSERT(m_executableMemory->codeStart());
         ASSERT(m_codePtr);
     }
     
@@ -395,7 +395,7 @@ public:
     {
         if (!m_executableMemory)
             return 0;
-        return m_executableMemory->sizeInBytes();
+        return m_executableMemory->codeSize();
     }
     
     bool tryToDisassemble(const char* prefix) const
diff --git a/src/3rdparty/masm/stubs/ExecutableAllocator.h b/src/3rdparty/masm/stubs/ExecutableAllocator.h
index a439c53827..f984704023 100644
--- a/src/3rdparty/masm/stubs/ExecutableAllocator.h
+++ b/src/3rdparty/masm/stubs/ExecutableAllocator.h
@@ -82,9 +82,14 @@ struct ExecutableMemoryHandle : public RefCounted<ExecutableMemoryHandle> {
 
     inline bool isManaged() const { return true; }
 
-    void *exceptionHandler() { return m_allocation->exceptionHandler(); }
-    void *start() { return m_allocation->start(); }
-    size_t sizeInBytes() { return m_size; }
+    void *memoryStart() { return m_allocation->memoryStart(); }
+    size_t memorySize() { return m_allocation->memorySize(); }
+
+    void *exceptionHandlerStart() { return m_allocation->exceptionHandlerStart(); }
+    size_t exceptionHandlerSize() { return m_allocation->exceptionHandlerSize(); }
+
+    void *codeStart() { return m_allocation->codeStart(); }
+    size_t codeSize() { return m_size; }
 
     QV4::ExecutableAllocator::ChunkOfPages *chunk() const
     { return m_allocator->chunkForAllocation(m_allocation); }