From 48fea8f8d84b25ebd4de780d8bb3fad907e81f73 Mon Sep 17 00:00:00 2001
From: Eggert Jung <eggert.s.jung@wischhof13.de>
Date: Tue, 24 Feb 2026 10:00:31 +0100
Subject: [PATCH] relocate stack

---
 kernel/thread/thread.cc | 27 ++++++++++++++++-----------
 kernel/thread/thread.h  |  6 ++++--
 user/app1/appl.cc       |  2 ++
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/kernel/thread/thread.cc b/kernel/thread/thread.cc
index 1ef7c70..098325b 100644
--- a/kernel/thread/thread.cc
+++ b/kernel/thread/thread.cc
@@ -35,38 +35,43 @@ void Thread::load_paging(Thread* t){
 
 Thread::Thread 	(bool kernel, void * startframe, int num_pages): queue_link(nullptr), isKernel(kernel), start(startframe), id(idCounter++), kill_flag(false){
 	StackPointer.isr = reinterpret_cast<void *>((uintptr_t)PageFrameAllocator::alloc(true)+STACK_SIZE);//(reserved_stack_space_isr + STACK_SIZE);
-	StackPointer.user = (void*)(0x4100000+STACK_SIZE);
+	StackPointer.user = (void*)(0x61FF000+STACK_SIZE);
 
 	paging_tree = (four_lvl_paging_t*)PageFrameAllocator::alloc(true);
 	create_basic_page_table(paging_tree, &identity_table);
+	appcode_table = (pagetable_t*) PageFrameAllocator::alloc(true);
 
-	subtable = (pagetable_t*) PageFrameAllocator::alloc(true);
+	assert(num_pages < 512); //limit for application code size is 2M
 	for(uint8_t i=0; i<num_pages; i++){
-		subtable->entries[i] = {
+		appcode_table->entries[i] = {
 			.present = 1,
 			.user = 1,
 			.address = ((uintptr_t)startframe >> 12) + i
 		};
 	}
+	// insert app code pages at 32*512*4096 = 0x4000000
+	paging_tree->l2->entries[32] = {
+		.present = 1,
+		.write = 1,
+		.user = 1,
+		.address = (uintptr_t)(appcode_table) >> 12
+	};
+
 	uintptr_t user_stackframe_p = ((uintptr_t)PageFrameAllocator::alloc(false));
-	subtable->entries[256] = {
+	appstack_table->entries[511] = {
 		.present = 1,
 		.write = 1,
 		.user = 1,
 		.address = user_stackframe_p >> 12
 	};
-
-	//pagetable_t* l2addr = (pagetable_t*)(paging_tree.l3.entries[0].address<<12);
-	//l2addr->entries[32] = {
-	paging_tree->l2->entries[32] = {
+	// insert stack page at 48*512*4096 = 0x6000000
+	paging_tree->l2->entries[48] = {
 		.present = 1,
 		.write = 1,
 		.user = 1,
-		.address = (uintptr_t)(subtable) >> 12
+		.address = (uintptr_t)(appstack_table) >> 12
 	};
 
-	//map_pageframe(&paging_tree, (uintptr_t)StackPointer.user, 0x4001000);
-
 	prepareContext(StackPointer.isr, context, kickoff, reinterpret_cast<uintptr_t>(this), 0, 0);
 }
 
diff --git a/kernel/thread/thread.h b/kernel/thread/thread.h
index 9e8ea84..e410d8b 100644
--- a/kernel/thread/thread.h
+++ b/kernel/thread/thread.h
@@ -34,7 +34,6 @@ class Thread {
 	void* start;
 
 
-	four_lvl_paging_t* paging_tree;
 
 	friend class Queue<Thread>;
 	friend class Semaphore;
@@ -75,7 +74,10 @@ class Thread {
 		void* isr;
 	} StackPointer;
 	void* operator new  ( size_t count )noexcept;
-	pagetable_t* subtable;
+
+	four_lvl_paging_t* paging_tree;
+	pagetable_t* appcode_table;
+	pagetable_t* appstack_table;
 
 	/*! \brief Unique thread id */
 	const int id;
diff --git a/user/app1/appl.cc b/user/app1/appl.cc
index 034bd94..9a9aef3 100644
--- a/user/app1/appl.cc
+++ b/user/app1/appl.cc
@@ -34,5 +34,7 @@ extern "C" void main() {
 		//	sys_exit();
 		//}
 		sleep(1000);
+		if(id == 2)
+			*reinterpret_cast<uint8_t*>(0xdeadbeaf) = 1;
 	}
 }