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GDB stub (melonDS-emu#1583)
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* gdbstub beginnings

* gdbstub: finish gdb impl things, next up is integration with melonDS

* holy fuck the gdbstub works

* gdb breakpoints work, but there's a mysterious crash on continue

* fix memory corruption that sometimes happened, and make resetting the console thru gdb work

* remove some gdb debug printing

* fix things in gdbstub

* separate option for enabling gdbstub

* add mode-dependent CPU registers

* C++ize the GDBstub code

* add gdbstub config in emu settings dialog

* make sure gdb is disabled when jit is enabled

* Remove unnecessary compiler flags, mark ARMJIT assembly code as no-execute-stack

This hardens the binary a little bit against common exploitation methods

* add option to wait for debugger attach on startup

* only insert GNU stack notes on linux

* disable gdbstub enable checkbox when jit is enabled

* fix non-linux incompatibilities

* enable gdbstub by default

* fix issues with gdbstub settings disable stuff

* format stuff

* update gdb test code

* Fix segfault when calling StubCallbacks->GetCPU()

C++ overrides are hard. Please I'm just a lowly C programmer.

* fix packet size not being sent correctly

Thanks to @GlowingUmbreon on Github for troubleshooting this

* fix select(2) calls (i should read docs more properly)

* fix GDB command sequencing/parsing issue (hopefully)

* [GDB] implement no-ack mode

* fix sending ack on handshake

* get lldb to work
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@PoroCYon
PoroCYon authored Oct 22, 2023
1 parent 3d58a33 commit 3ab752b
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Showing 29 changed files with 3,210 additions and 49 deletions.
2 changes: 1 addition & 1 deletion .gitignore
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@@ -1,4 +1,4 @@
build
build*/
bin
obj
*.depend
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5 changes: 5 additions & 0 deletions CMakeLists.txt
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Expand Up @@ -99,6 +99,11 @@ if (CCACHE)
set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE})
endif()

option(ENABLE_GDBSTUB "Enable GDB stub" ON)
if (ENABLE_GDBSTUB)
add_definitions(-DGDBSTUB_ENABLED)
endif()

option(BUILD_QT_SDL "Build Qt/SDL frontend" ON)

add_subdirectory(src)
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286 changes: 286 additions & 0 deletions src/ARM.cpp
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Expand Up @@ -25,6 +25,7 @@
#include "AREngine.h"
#include "ARMJIT.h"
#include "Platform.h"
#include "GPU.h"

#ifdef JIT_ENABLED
#include "ARMJIT.h"
Expand All @@ -34,6 +35,45 @@
using Platform::Log;
using Platform::LogLevel;

#ifdef GDBSTUB_ENABLED
void ARM::GdbCheckA()
{
if (!IsSingleStep && !BreakReq)
{ // check if eg. break signal is incoming etc.
Gdb::StubState st = GdbStub.Enter(false, Gdb::TgtStatus::NoEvent, ~(u32)0u, BreakOnStartup);
BreakOnStartup = false;
IsSingleStep = st == Gdb::StubState::Step;
BreakReq = st == Gdb::StubState::Attach || st == Gdb::StubState::Break;
}
}
void ARM::GdbCheckB()
{
if (IsSingleStep || BreakReq)
{ // use else here or we single-step the same insn twice in gdb
u32 pc_real = R[15] - ((CPSR & 0x20) ? 2 : 4);
Gdb::StubState st = GdbStub.Enter(true, Gdb::TgtStatus::SingleStep, pc_real);
IsSingleStep = st == Gdb::StubState::Step;
BreakReq = st == Gdb::StubState::Attach || st == Gdb::StubState::Break;
}
}
void ARM::GdbCheckC()
{
u32 pc_real = R[15] - ((CPSR & 0x20) ? 2 : 4);
Gdb::StubState st = GdbStub.CheckBkpt(pc_real, true, true);
if (st != Gdb::StubState::CheckNoHit)
{
IsSingleStep = st == Gdb::StubState::Step;
BreakReq = st == Gdb::StubState::Attach || st == Gdb::StubState::Break;
}
else GdbCheckB();
}
#else
ARM::GdbCheckA() {}
ARM::GdbCheckB() {}
ARM::GdbCheckC() {}
#endif


// instruction timing notes
//
// * simple instruction: 1S (code)
Expand Down Expand Up @@ -70,9 +110,22 @@ u32 ARM::ConditionTable[16] =


ARM::ARM(u32 num)
#ifdef GDBSTUB_ENABLED
: GdbStub(this, Platform::GetConfigInt(num ? Platform::GdbPortARM7 : Platform::GdbPortARM9))
#endif
{
// well uh
Num = num;

#ifdef GDBSTUB_ENABLED
if (Platform::GetConfigBool(Platform::GdbEnabled)
#ifdef JIT_ENABLED
&& !Platform::GetConfigBool(Platform::JIT_Enable)
#endif
)
GdbStub.Init();
IsSingleStep = false;
#endif
}

ARM::~ARM()
Expand Down Expand Up @@ -139,6 +192,13 @@ void ARM::Reset()
FastBlockLookupSize = 0;
#endif

#ifdef GDBSTUB_ENABLED
IsSingleStep = false;
BreakReq = false;
BreakOnStartup = Platform::GetConfigBool(
Num ? Platform::GdbARM7BreakOnStartup : Platform::GdbARM9BreakOnStartup);
#endif

// zorp
JumpTo(ExceptionBase);
}
Expand Down Expand Up @@ -571,8 +631,15 @@ void ARMv5::DataAbort()
JumpTo(ExceptionBase + 0x10);
}

void ARM::CheckGdbIncoming()
{
GdbCheckA();
}

void ARMv5::Execute()
{
GdbCheckB();

if (Halted)
{
if (Halted == 2)
Expand All @@ -596,6 +663,8 @@ void ARMv5::Execute()
{
if (CPSR & 0x20) // THUMB
{
GdbCheckC();

// prefetch
R[15] += 2;
CurInstr = NextInstr[0];
Expand All @@ -609,6 +678,8 @@ void ARMv5::Execute()
}
else
{
GdbCheckC();

// prefetch
R[15] += 4;
CurInstr = NextInstr[0];
Expand Down Expand Up @@ -723,6 +794,8 @@ void ARMv5::ExecuteJIT()

void ARMv4::Execute()
{
GdbCheckB();

if (Halted)
{
if (Halted == 2)
Expand All @@ -746,6 +819,8 @@ void ARMv4::Execute()
{
if (CPSR & 0x20) // THUMB
{
GdbCheckC();

// prefetch
R[15] += 2;
CurInstr = NextInstr[0];
Expand All @@ -758,6 +833,8 @@ void ARMv4::Execute()
}
else
{
GdbCheckC();

// prefetch
R[15] += 4;
CurInstr = NextInstr[0];
Expand Down Expand Up @@ -916,3 +993,212 @@ void ARMv4::FillPipeline()
NextInstr[1] = CodeRead32(R[15]);
}
}

#ifdef GDBSTUB_ENABLED
u32 ARM::ReadReg(Gdb::Register reg)
{
using Gdb::Register;
int r = static_cast<int>(reg);

if (reg < Register::pc) return R[r];
else if (reg == Register::pc)
{
return R[r] - ((CPSR & 0x20) ? 2 : 4);
}
else if (reg == Register::cpsr) return CPSR;
else if (reg == Register::sp_usr || reg == Register::lr_usr)
{
r -= static_cast<int>(Register::sp_usr);
if (ModeIs(0x10) || ModeIs(0x1f))
{
return R[13 + r];
}
else switch (CPSR & 0x1f)
{
case 0x11: return R_FIQ[5 + r];
case 0x12: return R_IRQ[0 + r];
case 0x13: return R_SVC[0 + r];
case 0x17: return R_ABT[0 + r];
case 0x1b: return R_UND[0 + r];
}
}
else if (reg >= Register::r8_fiq && reg <= Register::lr_fiq)
{
r -= static_cast<int>(Register::r8_fiq);
return ModeIs(0x11) ? R[ 8 + r] : R_FIQ[r];
}
else if (reg == Register::sp_irq || reg == Register::lr_irq)
{
r -= static_cast<int>(Register::sp_irq);
return ModeIs(0x12) ? R[13 + r] : R_IRQ[r];
}
else if (reg == Register::sp_svc || reg == Register::lr_svc)
{
r -= static_cast<int>(Register::sp_svc);
return ModeIs(0x13) ? R[13 + r] : R_SVC[r];
}
else if (reg == Register::sp_abt || reg == Register::lr_abt)
{
r -= static_cast<int>(Register::sp_abt);
return ModeIs(0x17) ? R[13 + r] : R_ABT[r];
}
else if (reg == Register::sp_und || reg == Register::lr_und)
{
r -= static_cast<int>(Register::sp_und);
return ModeIs(0x1b) ? R[13 + r] : R_UND[r];
}
else if (reg == Register::spsr_fiq) return ModeIs(0x11) ? CPSR : R_FIQ[7];
else if (reg == Register::spsr_irq) return ModeIs(0x12) ? CPSR : R_IRQ[2];
else if (reg == Register::spsr_svc) return ModeIs(0x13) ? CPSR : R_SVC[2];
else if (reg == Register::spsr_abt) return ModeIs(0x17) ? CPSR : R_ABT[2];
else if (reg == Register::spsr_und) return ModeIs(0x1b) ? CPSR : R_UND[2];

Log(LogLevel::Warn, "GDB reg read: unknown reg no %d\n", r);
return 0xdeadbeef;
}
void ARM::WriteReg(Gdb::Register reg, u32 v)
{
using Gdb::Register;
int r = static_cast<int>(reg);

if (reg < Register::pc) R[r] = v;
else if (reg == Register::pc) JumpTo(v);
else if (reg == Register::cpsr) CPSR = v;
else if (reg == Register::sp_usr || reg == Register::lr_usr)
{
r -= static_cast<int>(Register::sp_usr);
if (ModeIs(0x10) || ModeIs(0x1f))
{
R[13 + r] = v;
}
else switch (CPSR & 0x1f)
{
case 0x11: R_FIQ[5 + r] = v; break;
case 0x12: R_IRQ[0 + r] = v; break;
case 0x13: R_SVC[0 + r] = v; break;
case 0x17: R_ABT[0 + r] = v; break;
case 0x1b: R_UND[0 + r] = v; break;
}
}
else if (reg >= Register::r8_fiq && reg <= Register::lr_fiq)
{
r -= static_cast<int>(Register::r8_fiq);
*(ModeIs(0x11) ? &R[ 8 + r] : &R_FIQ[r]) = v;
}
else if (reg == Register::sp_irq || reg == Register::lr_irq)
{
r -= static_cast<int>(Register::sp_irq);
*(ModeIs(0x12) ? &R[13 + r] : &R_IRQ[r]) = v;
}
else if (reg == Register::sp_svc || reg == Register::lr_svc)
{
r -= static_cast<int>(Register::sp_svc);
*(ModeIs(0x13) ? &R[13 + r] : &R_SVC[r]) = v;
}
else if (reg == Register::sp_abt || reg == Register::lr_abt)
{
r -= static_cast<int>(Register::sp_abt);
*(ModeIs(0x17) ? &R[13 + r] : &R_ABT[r]) = v;
}
else if (reg == Register::sp_und || reg == Register::lr_und)
{
r -= static_cast<int>(Register::sp_und);
*(ModeIs(0x1b) ? &R[13 + r] : &R_UND[r]) = v;
}
else if (reg == Register::spsr_fiq)
{
*(ModeIs(0x11) ? &CPSR : &R_FIQ[7]) = v;
}
else if (reg == Register::spsr_irq)
{
*(ModeIs(0x12) ? &CPSR : &R_IRQ[2]) = v;
}
else if (reg == Register::spsr_svc)
{
*(ModeIs(0x13) ? &CPSR : &R_SVC[2]) = v;
}
else if (reg == Register::spsr_abt)
{
*(ModeIs(0x17) ? &CPSR : &R_ABT[2]) = v;
}
else if (reg == Register::spsr_und)
{
*(ModeIs(0x1b) ? &CPSR : &R_UND[2]) = v;
}
else Log(LogLevel::Warn, "GDB reg write: unknown reg no %d (write 0x%08x)\n", r, v);
}
u32 ARM::ReadMem(u32 addr, int size)
{
if (size == 8) return BusRead8(addr);
else if (size == 16) return BusRead16(addr);
else if (size == 32) return BusRead32(addr);
else return 0xfeedface;
}
void ARM::WriteMem(u32 addr, int size, u32 v)
{
if (size == 8) BusWrite8(addr, (u8)v);
else if (size == 16) BusWrite16(addr, (u16)v);
else if (size == 32) BusWrite32(addr, v);
}

void ARM::ResetGdb()
{
NDS::Reset();
GPU::StartFrame(); // need this to properly kick off the scheduler & frame output
}
int ARM::RemoteCmd(const u8* cmd, size_t len)
{
(void)len;

Log(LogLevel::Info, "[ARMGDB] Rcmd: \"%s\"\n", cmd);
if (!strcmp((const char*)cmd, "reset") || !strcmp((const char*)cmd, "r"))
{
Reset();
return 0;
}

return 1; // not implemented (yet)
}

void ARMv5::WriteMem(u32 addr, int size, u32 v)
{
if (addr < ITCMSize)
{
if (size == 8) *(u8*)&ITCM[addr & (ITCMPhysicalSize - 1)] = (u8)v;
else if (size == 16) *(u16*)&ITCM[addr & (ITCMPhysicalSize - 1)] = (u16)v;
else if (size == 32) *(u32*)&ITCM[addr & (ITCMPhysicalSize - 1)] = (u32)v;
else {}
return;
}
else if ((addr & DTCMMask) == DTCMBase)
{
if (size == 8) *(u8*)&DTCM[addr & (DTCMPhysicalSize - 1)] = (u8)v;
else if (size == 16) *(u16*)&DTCM[addr & (DTCMPhysicalSize - 1)] = (u16)v;
else if (size == 32) *(u32*)&DTCM[addr & (DTCMPhysicalSize - 1)] = (u32)v;
else {}
return;
}

ARM::WriteMem(addr, size, v);
}
u32 ARMv5::ReadMem(u32 addr, int size)
{
if (addr < ITCMSize)
{
if (size == 8) return *(u8*)&ITCM[addr & (ITCMPhysicalSize - 1)];
else if (size == 16) return *(u16*)&ITCM[addr & (ITCMPhysicalSize - 1)];
else if (size == 32) return *(u32*)&ITCM[addr & (ITCMPhysicalSize - 1)];
else return 0xfeedface;
}
else if ((addr & DTCMMask) == DTCMBase)
{
if (size == 8) return *(u8*)&DTCM[addr & (DTCMPhysicalSize - 1)];
else if (size == 16) return *(u16*)&DTCM[addr & (DTCMPhysicalSize - 1)];
else if (size == 32) return *(u32*)&DTCM[addr & (DTCMPhysicalSize - 1)];
else return 0xfeedface;
}

return ARM::ReadMem(addr, size);
}
#endif

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