From 259a1d56b04809690716fe0576fad9ea12782ce9 Mon Sep 17 00:00:00 2001
From: Drew Stratford <drewstratford@outlook.com>
Date: Wed, 4 Sep 2019 14:31:38 +1200
Subject: [PATCH] Thread: added member m_kernel_stack_top.

This value stores the top of a threads kernel_stack.
---
 Kernel/Thread.cpp | 6 ++++--
 Kernel/Thread.h   | 2 ++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index c90a796805..f9061c5930 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -57,14 +57,16 @@ Thread::Thread(Process& process)
         // FIXME: This memory is leaked.
         // But uh, there's also no kernel process termination, so I guess it's not technically leaked...
         m_kernel_stack_base = (u32)kmalloc_eternal(default_kernel_stack_size);
-        m_tss.esp = (m_kernel_stack_base + default_kernel_stack_size) & 0xfffffff8u;
+        m_kernel_stack_top = (m_kernel_stack_base + default_kernel_stack_size) & 0xfffffff8u;
+        m_tss.esp = m_kernel_stack_top;
 
     } else {
         // Ring3 processes need a separate stack for Ring0.
         m_kernel_stack_region = MM.allocate_kernel_region(default_kernel_stack_size, String::format("Kernel Stack (Thread %d)", m_tid));
         m_kernel_stack_base = m_kernel_stack_region->vaddr().get();
+        m_kernel_stack_top = m_kernel_stack_region->vaddr().offset(default_kernel_stack_size).get() & 0xfffffff8u;
         m_tss.ss0 = 0x10;
-        m_tss.esp0 = m_kernel_stack_region->vaddr().offset(default_kernel_stack_size).get() & 0xfffffff8u;
+        m_tss.esp0 = m_kernel_stack_top;
     }
 
     // HACK: Ring2 SS in the TSS is the current PID.
diff --git a/Kernel/Thread.h b/Kernel/Thread.h
index b52a3250fe..6c1f481212 100644
--- a/Kernel/Thread.h
+++ b/Kernel/Thread.h
@@ -273,6 +273,7 @@ public:
     u32 ticks_left() const { return m_ticks_left; }
 
     u32 kernel_stack_base() const { return m_kernel_stack_base; }
+    u32 kernel_stack_top() const { return m_kernel_stack_top; }
     u32 kernel_stack_for_signal_handler_base() const { return m_kernel_stack_for_signal_handler_region ? m_kernel_stack_for_signal_handler_region->vaddr().get() : 0; }
 
     void set_selector(u16 s) { m_far_ptr.selector = s; }
@@ -329,6 +330,7 @@ private:
     u32 m_pending_signals { 0 };
     u32 m_signal_mask { 0 };
     u32 m_kernel_stack_base { 0 };
+    u32 m_kernel_stack_top { 0 };
     RefPtr<Region> m_userspace_stack_region;
     RefPtr<Region> m_kernel_stack_region;
     RefPtr<Region> m_kernel_stack_for_signal_handler_region;