From 86c5d2ae2a1b43d493d5ebcb0bcee8c5baab80da Mon Sep 17 00:00:00 2001
From: Ziemas <ziemas@ziemas.se>
Date: Thu, 23 Apr 2026 03:04:11 +0200
Subject: [PATCH] DebugInterface: Allow stack tracing any IOP thread

---
 pcsx2/DebugTools/BiosDebugData.cpp  | 7 ++++---
 pcsx2/DebugTools/BiosDebugData.h    | 9 +++++----
 pcsx2/DebugTools/DebugInterface.cpp | 7 ++++++-
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/pcsx2/DebugTools/BiosDebugData.cpp b/pcsx2/DebugTools/BiosDebugData.cpp
index a825f54d7c..048a16bd03 100644
--- a/pcsx2/DebugTools/BiosDebugData.cpp
+++ b/pcsx2/DebugTools/BiosDebugData.cpp
@@ -49,7 +49,8 @@ std::vector<std::unique_ptr<BiosThread>> getIOPThreads()
 			return {};
 		}
 
-		data.stackTop = iopMemRead32(item + 0x3c);
+		data.stackBottom = iopMemRead32(item + 0x3c);
+		data.stackSize = iopMemRead32(item + 0x40);
 		data.status = iopMemRead8(item + 0xc);
 		data.tid = iopMemRead16(item + 0xa);
 		data.entrypoint = iopMemRead32(item + 0x38);
@@ -57,9 +58,9 @@ std::vector<std::unique_ptr<BiosThread>> getIOPThreads()
 		data.waitId = iopMemRead32(item + 0x20);
 		data.initPriority = iopMemRead16(item + 0xe);
 
-		data.SavedSP = iopMemRead32(item + 0x10);
+		data.regCtx = iopMemRead32(item + 0x10);
 
-		data.PC = iopMemRead32(data.SavedSP + 0x8c);
+		data.PC = iopMemRead32(data.regCtx + 0x8c);
 
 		threads.emplace_back(std::make_unique<IOPThread>(data));
 
diff --git a/pcsx2/DebugTools/BiosDebugData.h b/pcsx2/DebugTools/BiosDebugData.h
index de2b0ff432..2c3baa81db 100644
--- a/pcsx2/DebugTools/BiosDebugData.h
+++ b/pcsx2/DebugTools/BiosDebugData.h
@@ -59,8 +59,9 @@ struct IOPInternalThread
 {
 	u32 tid;
 	u32 PC;
-	u32 stackTop;
-	u32 SavedSP;
+	u32 stackBottom;
+	u32 stackSize;
+	u32 regCtx;
 	u32 status;
 	u32 entrypoint;
 	u32 waitstate;
@@ -189,9 +190,9 @@ public:
 	};
 	[[nodiscard]] u32 WaitId() const override { return data.waitId; };
 	[[nodiscard]] u32 EntryPoint() const override { return data.entrypoint; };
-	[[nodiscard]] u32 StackTop() const override { return data.stackTop; };
+	[[nodiscard]] u32 StackTop() const override { return data.stackBottom + data.stackSize; };
 	[[nodiscard]] u32 Priority() const override { return data.initPriority; };
-	[[nodiscard]] u32 RegCtx() const override { return 0; };
+	[[nodiscard]] u32 RegCtx() const override { return data.regCtx; };
 
 private:
 	IOPInternalThread data;
diff --git a/pcsx2/DebugTools/DebugInterface.cpp b/pcsx2/DebugTools/DebugInterface.cpp
index 584286b7f1..bc3e348987 100644
--- a/pcsx2/DebugTools/DebugInterface.cpp
+++ b/pcsx2/DebugTools/DebugInterface.cpp
@@ -1074,7 +1074,12 @@ std::vector<MipsStackWalk::StackFrame> R3000DebugInterface::StackTrace(const Bio
 			thread.EntryPoint(), thread.StackTop());
 	}
 
-	return {};
+	u32 p = thread.RegCtx();
+	u32 pc = Read32(p + 0x8c);
+	u32 ra = Read32(p + 0x7c);
+	u32 sp = Read32(p + 0x74);
+
+	return MipsStackWalk::Walk(this, pc, ra, sp, thread.EntryPoint(), thread.StackTop());
 }
 
 std::vector<IopMod> R3000DebugInterface::GetModuleList() const