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UserspaceEmulator: Add helpers for making loop instructions generic

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Use them to implement CMPSB/CMPSW/CMPSD.
This commit is contained in:
Andreas Kling 2020-07-18 00:10:21 +02:00
parent 28b6ba56aa
commit 485d1faf09
2 changed files with 138 additions and 22 deletions
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48
DevTools/UserspaceEmulator/SoftCPU.cpp
View file

@ -195,23 +195,9 @@ void SoftCPU::do_once_or_repeat(const X86::Instruction& insn, Callback callback)
if (!insn.has_rep_prefix())
return callback();
if (insn.has_address_size_override_prefix()) {
while (cx()) {
while (loop_index(insn.a32())) {
callback();
set_cx(cx() - 1);
if constexpr (check_zf) {
if (insn.rep_prefix() == X86::Prefix::REPZ && !zf())
break;
if (insn.rep_prefix() == X86::Prefix::REPNZ && zf())
break;
}
}
return;
}
while (ecx()) {
callback();
set_ecx(ecx() - 1);
decrement_loop_index(insn.a32());
if constexpr (check_zf) {
if (insn.rep_prefix() == X86::Prefix::REPZ && !zf())
break;
@ -1057,9 +1043,33 @@ void SoftCPU::CMOVcc_reg32_RM32(const X86::Instruction& insn)
gpr32(insn.reg32()) = insn.modrm().read32(*this, insn);
}
void SoftCPU::CMPSB(const X86::Instruction&) { TODO(); }
void SoftCPU::CMPSD(const X86::Instruction&) { TODO(); }
void SoftCPU::CMPSW(const X86::Instruction&) { TODO(); }
template<typename T>
ALWAYS_INLINE static void do_cmps(SoftCPU& cpu, const X86::Instruction& insn)
{
auto src_segment = cpu.segment(insn.segment_prefix().value_or(X86::SegmentRegister::DS));
cpu.do_once_or_repeat<true>(insn, [&] {
auto src = cpu.read_memory<T>({ src_segment, cpu.source_index(insn.a32()) });
auto dest = cpu.read_memory<T>({ cpu.es(), cpu.destination_index(insn.a32()) });
op_sub(cpu, dest, src);
cpu.step_source_index(insn.a32(), sizeof(T));
cpu.step_destination_index(insn.a32(), sizeof(T));
});
}
void SoftCPU::CMPSB(const X86::Instruction& insn)
{
do_cmps<u8>(*this, insn);
}
void SoftCPU::CMPSD(const X86::Instruction& insn)
{
do_cmps<u32>(*this, insn);
}
void SoftCPU::CMPSW(const X86::Instruction& insn)
{
do_cmps<u16>(*this, insn);
}
void SoftCPU::CMPXCHG_RM16_reg16(const X86::Instruction& insn)
{

112
DevTools/UserspaceEmulator/SoftCPU.h
View file

@ -140,6 +140,90 @@ public:
u32 gpr32(X86::RegisterIndex32 reg) const { return m_gpr[reg].full_u32; }
u32& gpr32(X86::RegisterIndex32 reg) { return m_gpr[reg].full_u32; }
template<typename T>
T gpr(unsigned register_index) const
{
if constexpr (sizeof(T) == 1)
return gpr8((X86::RegisterIndex8)register_index);
if constexpr (sizeof(T) == 2)
return gpr16((X86::RegisterIndex16)register_index);
if constexpr (sizeof(T) == 4)
return gpr32((X86::RegisterIndex32)register_index);
}
template<typename T>
T& gpr(unsigned register_index)
{
if constexpr (sizeof(T) == 1)
return gpr8((X86::RegisterIndex8)register_index);
if constexpr (sizeof(T) == 2)
return gpr16((X86::RegisterIndex16)register_index);
if constexpr (sizeof(T) == 4)
return gpr32((X86::RegisterIndex32)register_index);
}
u32 source_index(bool a32) const
{
if (a32)
return esi();
return si();
}
u32 destination_index(bool a32) const
{
if (a32)
return edi();
return di();
}
u32 loop_index(bool a32) const
{
if (a32)
return ecx();
return cx();
}
bool decrement_loop_index(bool a32)
{
if (a32) {
set_ecx(ecx() - 1);
return ecx() == 0;
}
set_cx(cx() - 1);
return cx() == 0;
}
ALWAYS_INLINE void step_source_index(bool a32, u32 step)
{
if (a32) {
if (df())
set_esi(esi() - step);
else
set_esi(esi() + step);
} else {
if (df())
set_si(si() - step);
else
set_si(si() + step);
}
}
ALWAYS_INLINE void step_destination_index(bool a32, u32 step)
{
if (a32) {
if (df())
set_edi(edi() - step);
else
set_edi(edi() + step);
} else {
if (df())
set_di(di() - step);
else
set_di(di() + step);
}
}
u32 eax() const { return gpr32(X86::RegisterEAX); }
u32 ebx() const { return gpr32(X86::RegisterEBX); }
u32 ecx() const { return gpr32(X86::RegisterECX); }
@ -253,10 +337,32 @@ public:
u16 read_memory16(X86::LogicalAddress);
u32 read_memory32(X86::LogicalAddress);
template<typename T>
T read_memory(X86::LogicalAddress address)
{
if constexpr (sizeof(T) == 1)
return read_memory8(address);
if constexpr (sizeof(T) == 2)
return read_memory16(address);
if constexpr (sizeof(T) == 4)
return read_memory32(address);
}
void write_memory8(X86::LogicalAddress, u8);
void write_memory16(X86::LogicalAddress, u16);
void write_memory32(X86::LogicalAddress, u32);
template<typename T>
void write_memory(X86::LogicalAddress address, T data)
{
if constexpr (sizeof(T) == 1)
return write_memory8(address, data);
if constexpr (sizeof(T) == 2)
return write_memory16(address, data);
if constexpr (sizeof(T) == 4)
return write_memory32(address, data);
}
bool evaluate_condition(u8 condition) const
{
switch (condition) {
@ -298,6 +404,9 @@ public:
return 0;
}
template<bool check_zf, typename Callback>
void do_once_or_repeat(const X86::Instruction& insn, Callback);
// ^X86::InstructionStream
virtual bool can_read() override { return false; }
virtual u8 read8() override;
@ -818,9 +927,6 @@ private:
template<typename Op>
void generic_RM32_CL(Op, const X86::Instruction&);
template<bool check_zf, typename Callback>
void do_once_or_repeat(const X86::Instruction& insn, Callback);
void update_code_cache();
void did_receive_secret_data();