fxos/lib/passes/syscall.cpp

//---
// fxos.passes.syscall: Detection and substitution of syscall addresses
//---

#include <fxos/disasm-passes/syscall.h>

namespace FxOS {

SyscallPass::SyscallPass(Disassembly &disasm, OS *os):
	InstructionDisassemblyPass(disasm, "syscall"), m_os(os)
{
}

void SyscallPass::analyze([[maybe_unused]] uint32_t pc,ConcreteInstruction &ci)
{
	/* Nothing to do if no syscall table is provided! */
	if(!m_os) return;

	Instruction const *i = ci.inst;
	if(!i) return;

	for(size_t n = 0; n < i->arg_count; n++)
	{
		Argument const &a = i->args[n];
		ConcreteInstructionArg &ca = ci.args[n];

		bool eligible = false;
		uint32_t address;

		if(a.kind == Argument::PcRel && ca.value
			&& ca.value.type == IntegerType::u32)
		{
			eligible = true;
			address = ca.value.read(0, 4);
		}
		if(a.kind == Argument::PcJump && ca.location
			&& RelConstDomain().is_constant(ca.location))
		{
			eligible = true;
			address = RelConstDomain().constant_value(ca.location);
		}

		if(eligible)
		{
			int sid = m_os->find_syscall(address);
			if(sid >= 0) ca.syscall_id = sid;
		}
	}
}

} /* namespace FxOS */