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LibWasm: Give traps a reason and display it when needed

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This makes debugging wasm code a bit easier, as we now know what fails
instead of just "too bad, something went wrong".
This commit is contained in:
Ali Mohammad Pur 2021-07-01 17:03:17 +04:30 • committed by Ali Mohammad Pur
parent 62ca81fdcc
commit b538e15548
10 changed files with 54 additions and 50 deletions
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44
Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
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@ -17,7 +17,7 @@ namespace Wasm {
#define TRAP_IF_NOT(x) \
do { \
if (trap_if_not(x)) { \
if (trap_if_not(x, #x)) { \
dbgln_if(WASM_TRACE_DEBUG, "Trapped because {} failed, at line {}", #x, __LINE__); \
return; \
} \
@ -25,14 +25,14 @@ namespace Wasm {
#define TRAP_IF_NOT_NORETURN(x) \
do { \
if (trap_if_not(x)) { \
if (trap_if_not(x, #x)) { \
dbgln_if(WASM_TRACE_DEBUG, "Trapped because {} failed, at line {}", #x, __LINE__); \
} \
} while (false)
void BytecodeInterpreter::interpret(Configuration& configuration)
{
m_do_trap = false;
m_trap.clear();
auto& instructions = configuration.frame().expression().instructions();
auto max_ip_value = InstructionPointer { instructions.size() };
auto& current_ip_value = configuration.ip();
@ -40,13 +40,13 @@ void BytecodeInterpreter::interpret(Configuration& configuration)
while (current_ip_value < max_ip_value) {
if (executed_instructions++ >= Constants::max_allowed_executed_instructions_per_call) [[unlikely]] {
m_do_trap = true;
m_trap = Trap { "Exceeded maximum allowed number of instructions" };
return;
}
auto& instruction = instructions[current_ip_value.value()];
auto old_ip = current_ip_value;
interpret(configuration, current_ip_value, instruction);
if (m_do_trap)
if (m_trap.has_value())
return;
if (current_ip_value == old_ip) // If no jump occurred
++current_ip_value;
@ -83,7 +83,7 @@ void BytecodeInterpreter::load_and_push(Configuration& configuration, Instructio
auto& address = configuration.frame().module().memories().first();
auto memory = configuration.store().get(address);
if (!memory) {
m_do_trap = true;
m_trap = Trap { "Nonexistent memory" };
return;
}
auto& arg = instruction.arguments().get<Instruction::MemoryArgument>();
@ -91,12 +91,12 @@ void BytecodeInterpreter::load_and_push(Configuration& configuration, Instructio
TRAP_IF_NOT(entry.has<Value>());
auto base = entry.get<Value>().to<i32>();
if (!base.has_value()) {
m_do_trap = true;
m_trap = Trap { "Memory access out of bounds" };
return;
}
auto instance_address = base.value() + static_cast<i64>(arg.offset);
if (instance_address < 0 || static_cast<u64>(instance_address + sizeof(ReadType)) > memory->size()) {
m_do_trap = true;
m_trap = Trap { "Memory access out of bounds" };
dbgln("LibWasm: Memory access out of bounds (expected 0 <= {} and {} <= {})", instance_address, instance_address + sizeof(ReadType), memory->size());
return;
}
@ -117,7 +117,7 @@ void BytecodeInterpreter::store_to_memory(Configuration& configuration, Instruct
TRAP_IF_NOT(base.has_value());
auto instance_address = base.value() + static_cast<i64>(arg.offset);
if (instance_address < 0 || static_cast<u64>(instance_address + data.size()) > memory->size()) {
m_do_trap = true;
m_trap = Trap { "Memory access out of bounds" };
dbgln("LibWasm: Memory access out of bounds (expected 0 <= {} and {} <= {})", instance_address, instance_address + data.size(), memory->size());
return;
}
@ -146,14 +146,14 @@ void BytecodeInterpreter::call_address(Configuration& configuration, FunctionAdd
configuration.stack().entries().remove(configuration.stack().size() - span.size(), span.size());
Result result { Trap {} };
Result result { Trap { ""sv } };
{
CallFrameHandle handle { *this, configuration };
result = configuration.call(*this, address, move(args));
}
if (result.is_trap()) {
m_do_trap = true;
m_trap = move(result.trap());
return;
}
@ -254,7 +254,7 @@ T BytecodeInterpreter::read_value(ReadonlyBytes data)
stream >> value;
if (stream.handle_any_error()) {
dbgln("Read from {} failed", data.data());
m_do_trap = true;
m_trap = Trap { "Read from memory failed" };
}
return value;
}
@ -266,7 +266,7 @@ float BytecodeInterpreter::read_value<float>(ReadonlyBytes data)
LittleEndian<u32> raw_value;
stream >> raw_value;
if (stream.handle_any_error())
m_do_trap = true;
m_trap = Trap { "Read from memory failed" };
return bit_cast<float>(static_cast<u32>(raw_value));
}
@ -277,7 +277,7 @@ double BytecodeInterpreter::read_value<double>(ReadonlyBytes data)
LittleEndian<u64> raw_value;
stream >> raw_value;
if (stream.handle_any_error())
m_do_trap = true;
m_trap = Trap { "Read from memory failed" };
return bit_cast<double>(static_cast<u64>(raw_value));
}
@ -319,7 +319,7 @@ template<typename V, typename T>
MakeSigned<T> BytecodeInterpreter::checked_signed_truncate(V value)
{
if (isnan(value) || isinf(value)) { // "undefined", let's just trap.
m_do_trap = true;
m_trap = Trap { "Signed truncation undefined behaviour" };
return 0;
}
@ -334,7 +334,7 @@ MakeSigned<T> BytecodeInterpreter::checked_signed_truncate(V value)
return static_cast<SignedT>(truncated);
dbgln_if(WASM_TRACE_DEBUG, "Truncate out of range error");
m_do_trap = true;
m_trap = Trap { "Signed truncation out of range" };
return true;
}
@ -342,7 +342,7 @@ template<typename V, typename T>
MakeUnsigned<T> BytecodeInterpreter::checked_unsigned_truncate(V value)
{
if (isnan(value) || isinf(value)) { // "undefined", let's just trap.
m_do_trap = true;
m_trap = Trap { "Unsigned truncation undefined behaviour" };
return 0;
}
double truncated;
@ -356,7 +356,7 @@ MakeUnsigned<T> BytecodeInterpreter::checked_unsigned_truncate(V value)
return static_cast<UnsignedT>(truncated);
dbgln_if(WASM_TRACE_DEBUG, "Truncate out of range error");
m_do_trap = true;
m_trap = Trap { "Unsigned truncation out of range" };
return true;
}
@ -490,7 +490,7 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
switch (instruction.opcode().value()) {
case Instructions::unreachable.value():
m_do_trap = true;
m_trap = Trap { "Unreachable" };
return;
case Instructions::nop.value():
return;
@ -1087,7 +1087,7 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
default:
unimplemented:;
dbgln("Instruction '{}' not implemented", instruction_name(instruction.opcode()));
m_do_trap = true;
m_trap = Trap { String::formatted("Unimplemented instruction {}", instruction_name(instruction.opcode())) };
return;
}
}
@ -1097,7 +1097,7 @@ void DebuggerBytecodeInterpreter::interpret(Configuration& configuration, Instru
if (pre_interpret_hook) {
auto result = pre_interpret_hook(configuration, ip, instruction);
if (!result) {
m_do_trap = true;
m_trap = Trap { "Trapped by user request" };
return;
}
}
@ -1106,7 +1106,7 @@ void DebuggerBytecodeInterpreter::interpret(Configuration& configuration, Instru
if (post_interpret_hook) {
auto result = post_interpret_hook(configuration, ip, instruction, *this);
if (!result) {
m_do_trap = true;
m_trap = Trap { "Trapped by user request" };
return;
}
}