Kernel: Move ThreadRegisters into arch-specific directory

These are architecture-specific anyway, so they belong in the Arch
directory. This commit also adds ThreadRegisters::set_initial_state to
factor out the logic in Thread.cpp.

Kernel/Arch/ThreadRegisters.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Platform.h>
+
+#if ARCH(X86_64)
+#    include <Kernel/Arch/x86_64/ThreadRegisters.h>
+#elif ARCH(AARCH64)
+#    include <Kernel/Arch/aarch64/ThreadRegisters.h>
+#else
+#    error "Unknown architecture"
+#endif

Kernel/Arch/aarch64/ThreadRegisters.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/Memory/AddressSpace.h>
+
+namespace Kernel {
+
+struct ThreadRegisters {
+    u64 x[31];
+    u64 elr_el1;
+    u64 sp_el0;
+
+    FlatPtr ip() const { return elr_el1; }
+    void set_ip(FlatPtr value) { elr_el1 = value; }
+
+    void set_sp(FlatPtr value) { sp_el0 = value; }
+
+    void set_initial_state(bool, Memory::AddressSpace&, FlatPtr kernel_stack_top)
+    {
+        set_sp(kernel_stack_top);
+    }
+};
+
+}

Kernel/Arch/x86_64/ThreadRegisters.h

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Platform.h>
+#include <AK/Types.h>
+#include <Kernel/Memory/AddressSpace.h>
+
+namespace Kernel {
+
+struct ThreadRegisters {
+    FlatPtr rdi;
+    FlatPtr rsi;
+    FlatPtr rbp;
+    FlatPtr rsp;
+    FlatPtr rbx;
+    FlatPtr rdx;
+    FlatPtr rcx;
+    FlatPtr rax;
+    FlatPtr r8;
+    FlatPtr r9;
+    FlatPtr r10;
+    FlatPtr r11;
+    FlatPtr r12;
+    FlatPtr r13;
+    FlatPtr r14;
+    FlatPtr r15;
+    FlatPtr rip;
+    FlatPtr rsp0;
+    FlatPtr cs;
+
+    FlatPtr rflags;
+    FlatPtr flags() const { return rflags; }
+    void set_flags(FlatPtr value) { rflags = value; }
+    void set_sp(FlatPtr value) { rsp = value; }
+    void set_sp0(FlatPtr value) { rsp0 = value; }
+    void set_ip(FlatPtr value) { rip = value; }
+
+    FlatPtr cr3;
+
+    FlatPtr ip() const
+    {
+        return rip;
+    }
+
+    FlatPtr sp() const
+    {
+        return rsp;
+    }
+
+    void set_initial_state(bool is_kernel_process, Memory::AddressSpace& space, FlatPtr kernel_stack_top)
+    {
+        // Only IF is set when a process boots.
+        set_flags(0x0202);
+
+        if (is_kernel_process)
+            cs = GDT_SELECTOR_CODE0;
+        else
+            cs = GDT_SELECTOR_CODE3 | 3;
+
+        cr3 = space.page_directory().cr3();
+
+        if (is_kernel_process) {
+            set_sp(kernel_stack_top);
+            set_sp0(kernel_stack_top);
+        } else {
+            // Ring 3 processes get a separate stack for ring 0.
+            // The ring 3 stack will be assigned by exec().
+            set_sp0(kernel_stack_top);
+        }
+    }
+};
+
+}

Kernel/Syscalls/thread.cpp

@@ -55,15 +55,17 @@ ErrorOr<FlatPtr> Process::sys$create_thread(void* (*entry)(void*), Userspace<Sys
 
     auto& regs = thread->regs();
     regs.set_ip((FlatPtr)entry);
-    regs.set_flags(0x0202);
     regs.set_sp(user_sp.value());
+
 #if ARCH(X86_64)
+    regs.set_flags(0x0202);
+    regs.cr3 = address_space().with([](auto& space) { return space->page_directory().cr3(); });
+
     regs.rdi = params.rdi;
     regs.rsi = params.rsi;
     regs.rdx = params.rdx;
     regs.rcx = params.rcx;
 #endif
-    regs.cr3 = address_space().with([](auto& space) { return space->page_directory().cr3(); });
 
     TRY(thread->make_thread_specific_region({}));
 

Kernel/Thread.cpp

@@ -77,33 +77,12 @@ Thread::Thread(NonnullLockRefPtr<Process> process, NonnullOwnPtr<Memory::Region>
 
     reset_fpu_state();
 
-    // Only IF is set when a process boots.
-    m_regs.set_flags(0x0202);
-
-#if ARCH(X86_64)
-    if (m_process->is_kernel_process())
-        m_regs.cs = GDT_SELECTOR_CODE0;
-    else
-        m_regs.cs = GDT_SELECTOR_CODE3 | 3;
-#elif ARCH(AARCH64)
-    TODO_AARCH64();
-#else
-#    error Unknown architecture
-#endif
-
-    m_regs.cr3 = m_process->address_space().with([](auto& space) { return space->page_directory().cr3(); });
-
     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() & ~(FlatPtr)0x7u;
 
-    if (m_process->is_kernel_process()) {
-        m_regs.set_sp(m_kernel_stack_top);
-        m_regs.set_sp0(m_kernel_stack_top);
-    } else {
-        // Ring 3 processes get a separate stack for ring 0.
-        // The ring 3 stack will be assigned by exec().
-        m_regs.set_sp0(m_kernel_stack_top);
-    }
+    m_process->address_space().with([&](auto& space) {
+        m_regs.set_initial_state(m_process->is_kernel_process(), *space, m_kernel_stack_top);
+    });
 
     // We need to add another reference if we could successfully create
     // all the resources needed for this thread. The reason for this is that

Kernel/Thread.h

@@ -17,6 +17,7 @@
 #include <AK/Vector.h>
 #include <Kernel/API/POSIX/sched.h>
 #include <Kernel/Arch/RegisterState.h>
+#include <Kernel/Arch/ThreadRegisters.h>
 #include <Kernel/Debug.h>
 #include <Kernel/Forward.h>
 #include <Kernel/KString.h>
@@ -49,55 +50,6 @@ struct ThreadSpecificData {
 
 #define THREAD_AFFINITY_DEFAULT 0xffffffff
 
-struct ThreadRegisters {
-#if ARCH(X86_64)
-    FlatPtr rdi;
-    FlatPtr rsi;
-    FlatPtr rbp;
-    FlatPtr rsp;
-    FlatPtr rbx;
-    FlatPtr rdx;
-    FlatPtr rcx;
-    FlatPtr rax;
-    FlatPtr r8;
-    FlatPtr r9;
-    FlatPtr r10;
-    FlatPtr r11;
-    FlatPtr r12;
-    FlatPtr r13;
-    FlatPtr r14;
-    FlatPtr r15;
-    FlatPtr rip;
-    FlatPtr rsp0;
-#endif
-    FlatPtr cs;
-
-#if ARCH(X86_64)
-    FlatPtr rflags;
-    FlatPtr flags() const { return rflags; }
-    void set_flags(FlatPtr value) { rflags = value; }
-    void set_sp(FlatPtr value) { rsp = value; }
-    void set_sp0(FlatPtr value) { rsp0 = value; }
-    void set_ip(FlatPtr value) { rip = value; }
-#endif
-
-    FlatPtr cr3;
-
-    FlatPtr ip() const
-    {
-#if ARCH(X86_64)
-        return rip;
-#endif
-    }
-
-    FlatPtr sp() const
-    {
-#if ARCH(X86_64)
-        return rsp;
-#endif
-    }
-};
-
 class Thread
     : public ListedRefCounted<Thread, LockType::Spinlock>
     , public LockWeakable<Thread> {