GDB stub (#1583)

* 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

1 files changed, 924 insertions, 0 deletions

diff --git a/src/debug/GdbCmds.cpp b/src/debug/GdbCmds.cpp
new file mode 100644
index 0000000..057502f
--- /dev/null
+++ b/src/debug/GdbCmds.cpp
@@ -0,0 +1,924 @@
+
+#include <stdio.h>
+#include <assert.h>
+
+#include "../CRC32.h"
+#include "../Platform.h"
+#include "hexutil.h"
+
+#include "GdbProto.h"
+
+using Platform::Log;
+using Platform::LogLevel;
+
+namespace Gdb
+{
+
+enum class GdbSignal : int
+{
+	INT  = 2,
+	TRAP = 5,
+	EMT  = 7, // "emulation trap"
+	SEGV = 11,
+	ILL  = 4
+};
+
+// 12: llvm::MachO::CPU_TYPE_ARM
+// 5: llvm::MachO::CPU_SUBTYPE_ARM_V4T
+// 7: llvm::MachO::CPU_SUBTYPE_ARM_V5TEJ
+const char* TARGET_INFO_ARM7 = "cputype:12;cpusubtype:5;triple:arm-none-eabi;ostype:none;vendor:none;endian:little;ptrsize:4;";
+const char* TARGET_INFO_ARM9 = "cputype:12;cpusubtype:7;triple:arm-none-eabi;ostype:none;vendor:none;endian:little;ptrsize:4;";
+
+
+#define TARGET_XML__CORE_REGS \
+	"<reg name=\"r0\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r1\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r2\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r3\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r4\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r5\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r6\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r7\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r8\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r9\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r10\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r11\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"r12\" bitsize=\"32\" type=\"uint32\"/>" \
+	"<reg name=\"sp\" bitsize=\"32\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr\" bitsize=\"32\" type=\"code_ptr\"/>" \
+	"<reg name=\"pc\" bitsize=\"32\" type=\"code_ptr\"/>" \
+	/* 16 regs */ \
+
+#define TARGET_XML__MODE_REGS \
+	"<reg name=\"cpsr\" bitsize=\"32\" regnum=\"25\"/>" \
+	"<reg name=\"sp_usr\" bitsize=\"32\" regnum=\"26\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_usr\" bitsize=\"32\" regnum=\"27\" type=\"code_ptr\"/>" \
+	"<reg name=\"r8_fiq\" bitsize=\"32\" type=\"uint32\" regnum=\"28\"/>" \
+	"<reg name=\"r9_fiq\" bitsize=\"32\" type=\"uint32\" regnum=\"29\"/>" \
+	"<reg name=\"r10_fiq\" bitsize=\"32\" type=\"uint32\" regnum=\"30\"/>" \
+	"<reg name=\"r11_fiq\" bitsize=\"32\" type=\"uint32\" regnum=\"31\"/>" \
+	"<reg name=\"r12_fiq\" bitsize=\"32\" type=\"uint32\" regnum=\"32\"/>" \
+	"<reg name=\"sp_fiq\" bitsize=\"32\" regnum=\"33\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_fiq\" bitsize=\"32\" regnum=\"34\" type=\"code_ptr\"/>" \
+	"<reg name=\"sp_irq\" bitsize=\"32\" regnum=\"35\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_irq\" bitsize=\"32\" regnum=\"36\" type=\"code_ptr\"/>" \
+	"<reg name=\"sp_svc\" bitsize=\"32\" regnum=\"37\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_svc\" bitsize=\"32\" regnum=\"38\" type=\"code_ptr\"/>" \
+	"<reg name=\"sp_abt\" bitsize=\"32\" regnum=\"39\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_abt\" bitsize=\"32\" regnum=\"40\" type=\"code_ptr\"/>" \
+	"<reg name=\"sp_und\" bitsize=\"32\" regnum=\"41\" type=\"data_ptr\"/>" \
+	"<reg name=\"lr_und\" bitsize=\"32\" regnum=\"42\" type=\"code_ptr\"/>" \
+	"<reg name=\"spsr_fiq\" bitsize=\"32\" regnum=\"43\"/>" \
+	"<reg name=\"spsr_irq\" bitsize=\"32\" regnum=\"44\"/>" \
+	"<reg name=\"spsr_svc\" bitsize=\"32\" regnum=\"45\"/>" \
+	"<reg name=\"spsr_abt\" bitsize=\"32\" regnum=\"46\"/>" \
+	"<reg name=\"spsr_und\" bitsize=\"32\" regnum=\"47\"/>" \
+	/* 23 regs */ \
+
+
+const char* TARGET_XML_ARM7 =
+	"<target version=\"1.0\">"
+	"<architecture>armv4t</architecture>"
+	"<osabi>none</osabi>"
+	"<feature name=\"org.gnu.gdb.arm.core\">"
+	TARGET_XML__CORE_REGS
+	TARGET_XML__MODE_REGS
+	// 39 regs total
+	"</feature>"
+	"</target>";
+
+
+const char* TARGET_XML_ARM9 =
+	"<target version=\"1.0\">"
+	"<architecture>armv5te</architecture>"
+	"<osabi>none</osabi>"
+	"<feature name=\"org.gnu.gdb.arm.core\">"
+	TARGET_XML__CORE_REGS
+	TARGET_XML__MODE_REGS
+	// 39 regs total
+	"</feature>"
+	"</target>";
+	// TODO: CP15?
+
+
+static int DoQResponse(GdbStub* stub, const u8* query, const char* data, const size_t len)
+{
+	size_t qaddr, qlen;
+
+	Log(LogLevel::Debug, "[GDB qresp] query='%s'\n", query);
+	if (sscanf((const char*)query, "%zx,%zx", &qaddr, &qlen) != 2)
+	{
+		return stub->RespStr("E01");
+	}
+	else if (qaddr >  len)
+	{
+		return stub->RespStr("E01");
+	}
+	else if (qaddr == len)
+	{
+		return stub->RespStr("l");
+	}
+
+	size_t bleft = len - qaddr;
+	size_t outlen = qlen;
+	if (outlen > bleft) outlen = bleft;
+	Log(LogLevel::Debug, "[GDB qresp] qaddr=%zu qlen=%zu left=%zu outlen=%zu\n",
+			qaddr, qlen, bleft, outlen);
+
+	return stub->RespC("m", 1, (const u8*)&data[qaddr], outlen);
+}
+
+__attribute__((__aligned__(4)))
+static u8 tempdatabuf[1024];
+
+ExecResult GdbStub::Handle_g(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u8* regstrbuf = tempdatabuf;
+
+	for (size_t i = 0; i < GDB_ARCH_N_REG; ++i)
+	{
+		u32 v = stub->Cb->ReadReg(static_cast<Register>(i));
+		hexfmt32(&regstrbuf[i*4*2], v);
+	}
+
+	stub->Resp(regstrbuf, GDB_ARCH_N_REG*4*2);
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_G(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	if (len != GDB_ARCH_N_REG*4*2)
+	{
+		Log(LogLevel::Error, "[GDB] REG WRITE ERR: BAD LEN: %zd != %d!\n", len, GDB_ARCH_N_REG*4*2);
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	for (int i = 0; i < GDB_ARCH_N_REG; ++i)
+	{
+		u32 v = unhex32(&cmd[i*4*2]);
+		stub->Cb->WriteReg(static_cast<Register>(i), v);
+	}
+
+	stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_m(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u32 addr = 0, llen = 0, end;
+
+	if (sscanf((const char*)cmd, "%08X,%08X", &addr, &llen) != 2)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+	else if (llen > (GDBPROTO_BUFFER_CAPACITY/2))
+	{
+		stub->RespStr("E02");
+		return ExecResult::Ok;
+	}
+	end = addr + llen;
+
+	u8* datastr = tempdatabuf;
+	u8* dataptr = datastr;
+
+	// pre-align: byte
+	if ((addr & 1))
+	{
+		if ((end-addr) >= 1)
+		{
+			u32 v = stub->Cb->ReadMem(addr, 8);
+			hexfmt8(dataptr, v&0xff);
+			++addr;
+			dataptr += 2;
+		}
+		else goto end;
+	}
+
+	// pre-align: short
+	if ((addr & 2))
+	{
+		if ((end-addr) >= 2)
+		{
+			u32 v = stub->Cb->ReadMem(addr, 16);
+			hexfmt16(dataptr, v&0xffff);
+			addr += 2;
+			dataptr += 4;
+		}
+		else if ((end-addr) == 1)
+		{ // last byte
+			u32 v = stub->Cb->ReadMem(addr, 8);
+			hexfmt8(dataptr, v&0xff);
+			++addr;
+			dataptr += 2;
+		}
+		else goto end;
+	}
+
+	// main loop: 4-byte chunks
+	while (addr < end)
+	{
+		if (end - addr < 4) break; // post-align stuff
+
+		u32 v = stub->Cb->ReadMem(addr, 32);
+		hexfmt32(dataptr, v);
+		addr += 4;
+		dataptr += 8;
+	}
+
+	// post-align: short
+	if ((end-addr) & 2)
+	{
+		u32 v = stub->Cb->ReadMem(addr, 16);
+		hexfmt16(dataptr, v&0xffff);
+		addr += 2;
+		dataptr += 4;
+	}
+
+	// post-align: byte
+	if ((end-addr) == 1)
+	{
+		u32 v = stub->Cb->ReadMem(addr, 8);
+		hexfmt8(dataptr, v&0xff);
+		++addr;
+		dataptr += 2;
+	}
+
+end:
+	assert(addr == end);
+
+	stub->Resp(datastr, llen*2);
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_M(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u32 addr, llen, end;
+	int inoff;
+
+	if (sscanf((const char*)cmd, "%08X,%08X:%n", &addr, &llen, &inoff) != 2)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+	else if (llen > (GDBPROTO_BUFFER_CAPACITY/2))
+	{
+		stub->RespStr("E02");
+		return ExecResult::Ok;
+	}
+	end = addr + llen;
+
+	const u8* dataptr = cmd + inoff;
+
+	// pre-align: byte
+	if ((addr & 1))
+	{
+		if ((end-addr) >= 1)
+		{
+			u8 v = unhex8(dataptr);
+			stub->Cb->WriteMem(addr, 8, v);
+			++addr;
+			dataptr += 2;
+		}
+		else goto end;
+	}
+
+	// pre-align: short
+	if ((addr & 2))
+	{
+		if ((end-addr) >= 2)
+		{
+			u16 v = unhex16(dataptr);
+			stub->Cb->WriteMem(addr, 16, v);
+			addr += 2;
+			dataptr += 4;
+		}
+		else if ((end-addr) == 1)
+		{ // last byte
+			u8 v = unhex8(dataptr);
+			stub->Cb->WriteMem(addr, 8, v);
+			++addr;
+			dataptr += 2;
+		}
+		else goto end;
+	}
+
+	// main loop: 4-byte chunks
+	while (addr < end)
+	{
+		if (end - addr < 4) break; // post-align stuff
+
+		u32 v = unhex32(dataptr);
+		stub->Cb->WriteMem(addr, 32, v);
+		addr += 4;
+		dataptr += 8;
+	}
+
+	// post-align: short
+	if ((end-addr) & 2)
+	{
+		u16 v = unhex16(dataptr);
+		stub->Cb->WriteMem(addr, 16, v);
+		addr += 2;
+		dataptr += 4;
+	}
+
+	// post-align: byte
+	if ((end-addr) == 1)
+	{
+		u8 v = unhex8(dataptr);
+		stub->Cb->WriteMem(addr, 8, v);
+		++addr;
+		dataptr += 2;
+	}
+
+end:
+	assert(addr == end);
+
+	stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_X(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u32 addr, llen, end;
+	int inoff;
+
+	if (sscanf((const char*)cmd, "%08X,%08X:%n", &addr, &llen, &inoff) != 2)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+	else if (llen > (GDBPROTO_BUFFER_CAPACITY/2))
+	{
+		stub->RespStr("E02");
+		return ExecResult::Ok;
+	}
+	end = addr + llen;
+
+	const u8* dataptr = cmd + inoff;
+
+	// pre-align: byte
+	if ((addr & 1))
+	{
+		if ((end-addr) >= 1)
+		{
+			u8 v = *dataptr;
+			stub->Cb->WriteMem(addr, 8, v);
+			++addr;
+			dataptr += 1;
+		}
+		else goto end;
+	}
+
+	// pre-align: short
+	if ((addr & 2))
+	{
+		if ((end-addr) >= 2)
+		{
+			u16 v = dataptr[0] | ((u16)dataptr[1] << 8);
+			stub->Cb->WriteMem(addr, 16, v);
+			addr += 2;
+			dataptr += 2;
+		}
+		else if ((end-addr) == 1)
+		{ // last byte
+			u8 v = *dataptr;
+			stub->Cb->WriteMem(addr, 8, v);
+			++addr;
+			dataptr += 1;
+		}
+		else goto end;
+	}
+
+	// main loop: 4-byte chunks
+	while (addr < end)
+	{
+		if (end - addr < 4) break; // post-align stuff
+
+		u32 v = dataptr[0] | ((u32)dataptr[1] << 8)
+			| ((u32)dataptr[2] << 16) | ((u32)dataptr[3] << 24);
+		stub->Cb->WriteMem(addr, 32, v);
+		addr += 4;
+		dataptr += 4;
+	}
+
+	// post-align: short
+	if ((end-addr) & 2)
+	{
+		u16 v = dataptr[0] | ((u16)dataptr[1] << 8);
+		stub->Cb->WriteMem(addr, 16, v);
+		addr += 2;
+		dataptr += 2;
+	}
+
+	// post-align: byte
+	if ((end-addr) == 1)
+	{
+		u8 v = unhex8(dataptr);
+		stub->Cb->WriteMem(addr, 8, v);
+		++addr;
+		dataptr += 1;
+	}
+
+end:
+	assert(addr == end);
+
+	stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_c(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u32 addr = ~(u32)0;
+
+	if (len > 0)
+	{
+		if (len <= 8)
+		{
+			if (sscanf((const char*)cmd, "%08X", &addr) != 1)
+			{
+				stub->RespStr("E01");
+			} // else: ok
+		}
+		else
+		{
+			stub->RespStr("E01");
+		}
+	} // else: continue at current
+
+	if (~addr)
+	{
+		stub->Cb->WriteReg(Register::pc, addr);
+	}
+
+	return ExecResult::Continue;
+}
+
+ExecResult GdbStub::Handle_s(GdbStub* stub, const u8* cmd, ssize_t len) {
+	u32 addr = ~(u32)0;
+
+	if (len > 0)
+	{
+		if (len <= 8)
+		{
+			if (sscanf((const char*)cmd, "%08X", &addr) != 1) {
+				stub->RespStr("E01");
+				return ExecResult::Ok;
+			} // else: ok
+		}
+		else
+		{
+			stub->RespStr("E01");
+			return ExecResult::Ok;
+		}
+	} // else: continue at current
+
+	if (~addr != 0)
+	{
+		stub->Cb->WriteReg(Register::pc, addr);
+	}
+
+	return ExecResult::Step;
+}
+
+ExecResult GdbStub::Handle_p(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	int reg;
+	if (sscanf((const char*)cmd, "%x", &reg) != 1 || reg < 0 || reg >= GDB_ARCH_N_REG)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	u32 v = stub->Cb->ReadReg(static_cast<Register>(reg));
+	hexfmt32(tempdatabuf, v);
+	stub->Resp(tempdatabuf, 4*2);
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_P(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	int reg, dataoff;
+
+	if (sscanf((const char*)cmd, "%x=%n", &reg, &dataoff) != 1 || reg < 0
+			|| reg >= GDB_ARCH_N_REG || dataoff + 4*2 > len)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	u32 v = unhex32(&cmd[dataoff]);
+	stub->Cb->WriteReg(static_cast<Register>(reg), v);
+
+	stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_H(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	u8 operation = cmd[0];
+	u32 thread_id;
+	sscanf((const char*)&cmd[1], "%u", &thread_id);
+
+	(void)operation;
+	if (thread_id <= 1)
+	{
+		stub->RespStr("OK");
+	}
+	else
+	{
+		stub->RespStr("E01");
+	}
+
+	return ExecResult::Ok;
+}
+
+
+ExecResult GdbStub::Handle_Question(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	// "request reason for target halt" (which must also halt)
+
+	TgtStatus st = stub->Stat;
+	u32 arg = ~(u32)0;
+	int typ = 0;
+
+	switch (st)
+	{
+	case TgtStatus::None: // no target!
+		stub->RespStr("W00");
+		break;
+
+	case TgtStatus::Running: // will break very soon due to retval
+	case TgtStatus::BreakReq:
+		stub->RespFmt("S%02X", GdbSignal::INT);
+		break;
+
+	case TgtStatus::SingleStep:
+		stub->RespFmt("S%02X", GdbSignal::TRAP);
+		break;
+
+	case TgtStatus::Bkpt:
+		arg = stub->CurBkpt;
+		typ = 1;
+		goto bkpt_rest;
+	case TgtStatus::Watchpt:
+		arg = stub->CurWatchpt;
+		typ = 2;
+	bkpt_rest:
+		if (!~arg)
+		{
+			stub->RespFmt("S%02X", GdbSignal::TRAP);
+		}
+		else
+		{
+			switch (typ)
+			{
+			case 1:
+				stub->RespFmt("S%02X", GdbSignal::TRAP);
+				//stub->RespFmt("T%02Xhwbreak:"/*"%08X"*/";", GdbSignal::TRAP/*, arg*/);
+				break;
+			case 2:
+				stub->RespFmt("S%02X", GdbSignal::TRAP);
+				//stub->RespFmt("T%02Xwatch:"/*"%08X"*/";", GdbSignal::TRAP/*, arg*/);
+				break;
+			default:
+				stub->RespFmt("S%02X", GdbSignal::TRAP);
+				break;
+			}
+		}
+		break;
+	case TgtStatus::BkptInsn:
+		stub->RespFmt("T%02Xswbreak:%08X;", GdbSignal::TRAP,
+				stub->Cb->ReadReg(Register::pc));
+		break;
+
+		// these three should technically be a SIGBUS but gdb etc don't really
+		// like that (plus it sounds confusing)
+	case TgtStatus::FaultData:
+	case TgtStatus::FaultIAcc:
+		stub->RespFmt("S%02X", GdbSignal::SEGV);
+		break;
+	case TgtStatus::FaultInsn:
+		stub->RespFmt("S%02X", GdbSignal::ILL);
+		break;
+	default: break;
+	}
+
+	return ExecResult::InitialBreak;
+}
+
+ExecResult GdbStub::Handle_Exclamation(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("OK");
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_D(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("OK");
+	return ExecResult::Detached;
+}
+
+ExecResult GdbStub::Handle_r(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->Cb->ResetGdb();
+	return ExecResult::Ok;
+}
+ExecResult GdbStub::Handle_R(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->Cb->ResetGdb();
+	return ExecResult::Ok;
+}
+ExecResult GdbStub::Handle_k(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	return ExecResult::Detached;
+}
+
+
+ExecResult GdbStub::Handle_z(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	int typ;
+	u32 addr, kind;
+
+	if (sscanf((const char*)cmd, "%d,%x,%u", &typ, &addr, &kind) != 3)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	switch (typ)
+	{
+	case 0: case 1: // remove breakpoint (we cheat & always insert a hardware breakpoint)
+		stub->DelBkpt(addr, kind);
+		break;
+	case 2: case 3: case 4: // watchpoint. currently not distinguishing between reads & writes oops
+		stub->DelWatchpt(addr, kind, typ);
+		break;
+	default:
+		stub->RespStr("E02");
+		return ExecResult::Ok;
+	}
+
+	stub->RespStr("OK");
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_Z(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	int typ;
+	u32 addr, kind;
+
+	if (sscanf((const char*)cmd, "%d,%x,%u", &typ, &addr, &kind) != 3)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	switch (typ)
+	{
+	case 0: case 1: // insert breakpoint (we cheat & always insert a hardware breakpoint)
+		stub->AddBkpt(addr, kind);
+		break;
+	case 2: case 3: case 4: // watchpoint. currently not distinguishing between reads & writes oops
+		stub->AddWatchpt(addr, kind, typ);
+		break;
+	default:
+		stub->RespStr("E02");
+		return ExecResult::Ok;
+	}
+
+	stub->RespStr("OK");
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_HostInfo(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	const char* resp = "";
+
+	switch (stub->Cb->GetCPU())
+	{
+	case 7: resp = TARGET_INFO_ARM7; break;
+	case 9: resp = TARGET_INFO_ARM9; break;
+	default: break;
+	}
+
+	stub->RespStr(resp);
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_Rcmd(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+
+	memset(tempdatabuf, 0, sizeof tempdatabuf);
+	for (ssize_t i = 0; i < len/2; ++i)
+	{
+		tempdatabuf[i] = unhex8(&cmd[i*2]);
+	}
+
+	int r = stub->Cb->RemoteCmd(tempdatabuf, len/2);
+
+	if (r) stub->RespFmt("E%02X", r&0xff);
+	else stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_Supported(GdbStub* stub,
+		const u8* cmd, ssize_t len) {
+	// TODO: support Xfer:memory-map:read::
+	//       but NWRAM is super annoying with that
+	stub->RespFmt("PacketSize=%X;qXfer:features:read+;swbreak-;hwbreak+;QStartNoAckMode+", GDBPROTO_BUFFER_CAPACITY-1);
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_CRC(GdbStub* stub,
+		const u8* cmd, ssize_t llen)
+{
+	static u8 crcbuf[128];
+
+	u32 addr, len;
+	if (sscanf((const char*)cmd, "%x,%x", &addr, &len) != 2)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	u32 val = 0; // start at 0
+	u32 caddr = addr;
+	u32 realend = addr + len;
+
+	for (; caddr < addr + len; )
+	{
+		// calc partial CRC in 128-byte chunks
+		u32 end = caddr + sizeof(crcbuf)/sizeof(crcbuf[0]);
+		if (end > realend) end = realend;
+		u32 clen = end - caddr;
+
+		for (size_t i = 0; caddr < end; ++caddr, ++i)
+		{
+			crcbuf[i] = stub->Cb->ReadMem(caddr, 8);
+		}
+
+		val = CRC32(crcbuf, clen, val);
+	}
+
+	stub->RespFmt("C%x", val);
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_C(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("QC1"); // current thread ID is 1
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_fThreadInfo(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("m1"); // one thread
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_sThreadInfo(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("l"); // end of thread list
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_features(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	const char* resp;
+
+	Log(LogLevel::Debug, "[GDB] CPU type = %d\n", stub->Cb->GetCPU());
+	switch (stub->Cb->GetCPU())
+	{
+	case 7: resp = TARGET_XML_ARM7; break;
+	case 9: resp = TARGET_XML_ARM9; break;
+	default: resp = ""; break;
+	}
+
+	DoQResponse(stub, cmd, resp, strlen(resp));
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_q_Attached(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("1"); // always "attach to a process"
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_Attach(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+
+	TgtStatus st = stub->Stat;
+
+	if (st == TgtStatus::None)
+	{
+		// no target
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	stub->RespStr("T05thread:1;");
+
+	if (st == TgtStatus::Running) return ExecResult::MustBreak;
+	else return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_Kill(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	TgtStatus st = stub->Stat;
+
+	stub->Cb->ResetGdb();
+
+	stub->RespStr("OK");
+
+	return (st != TgtStatus::Running && st != TgtStatus::None) ? ExecResult::Detached : ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_Run(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	TgtStatus st = stub->Stat;
+
+	stub->Cb->ResetGdb();
+
+	// TODO: handle cmdline for homebrew?
+
+	return (st != TgtStatus::Running && st != TgtStatus::None) ? ExecResult::Continue : ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_Stopped(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	TgtStatus st = stub->Stat;
+
+	static bool notified = true;
+
+	// not sure if i understand this correctly
+	if (st != TgtStatus::Running)
+	{
+		if (notified) stub->RespStr("OK");
+		else stub->RespStr("W00");
+
+		notified = !notified;
+	}
+	else stub->RespStr("OK");
+
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_MustReplyEmpty(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->Resp(NULL, 0);
+	return ExecResult::Ok;
+}
+
+ExecResult GdbStub::Handle_v_Cont(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	if (len < 1)
+	{
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+
+	switch (cmd[0])
+	{
+	case 'c':
+		stub->RespStr("OK");
+		return ExecResult::Continue;
+	case 's':
+		stub->RespStr("OK");
+		return ExecResult::Step;
+	case 't':
+		stub->RespStr("OK");
+		return ExecResult::MustBreak;
+	default:
+		stub->RespStr("E01");
+		return ExecResult::Ok;
+	}
+}
+
+ExecResult GdbStub::Handle_v_ContQuery(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->RespStr("vCont;c;s;t");
+	return ExecResult::Ok;
+}
+
+
+ExecResult GdbStub::Handle_Q_StartNoAckMode(GdbStub* stub, const u8* cmd, ssize_t len)
+{
+	stub->NoAck = true;
+	stub->RespStr("OK");
+	return ExecResult::Ok;
+}
+
+}
+