Kernel: Consolidate a bunch of i386/x86_64 code paths

Add some arch-specific getters and setters that allow us to merge blocks
that were previously specific to either ARCH(I386) or ARCH(X86_64).

6 files changed, 64 insertions, 117 deletions

diff --git a/Kernel/Arch/x86/RegisterState.h b/Kernel/Arch/x86/RegisterState.h
index 21e9fe13cd..cefd54209b 100644
--- a/Kernel/Arch/x86/RegisterState.h
+++ b/Kernel/Arch/x86/RegisterState.h
@@ -68,41 +68,35 @@ struct [[gnu::packed]] RegisterState {
     FlatPtr userspace_ss;
 #endif
 
+#if ARCH(I386)
     FlatPtr userspace_sp() const
     {
-#if ARCH(I386)
         return userspace_esp;
-#else
-        return userspace_rsp;
-#endif
     }
-
-    FlatPtr ip() const
-    {
-#if ARCH(I386)
-        return eip;
-#else
-        return rip;
-#endif
-    }
-
-    FlatPtr bp() const
+    void set_userspace_sp(FlatPtr value) { userspace_esp = value; }
+    FlatPtr ip() const { return eip; }
+    void set_ip(FlatPtr value) { eip = value; }
+    void set_dx(FlatPtr value) { edx = value; }
+    FlatPtr bp() const { return ebp; }
+    void set_bp(FlatPtr value) { ebp = value; }
+    FlatPtr flags() const { return eflags; }
+    void set_flags(FlatPtr value) { eflags = value; }
+    void set_return_reg(FlatPtr value) { eax = value; }
+#elif ARCH(X86_64)
+    FlatPtr userspace_sp() const
     {
-#if ARCH(I386)
-        return ebp;
-#else
-        return rbp;
-#endif
+        return userspace_rsp;
     }
-
-    FlatPtr flags() const
-    {
-#if ARCH(I386)
-        return eflags;
-#else
-        return rflags;
+    void set_userspace_sp(FlatPtr value) { userspace_rsp = value; }
+    FlatPtr ip() const { return rip; }
+    void set_ip(FlatPtr value) { rip = value; }
+    void set_dx(FlatPtr value) { rdx = value; }
+    FlatPtr bp() const { return rbp; }
+    void set_bp(FlatPtr value) { rbp = value; }
+    FlatPtr flags() const { return rflags; }
+    void set_flags(FlatPtr value) { rflags = value; }
+    void set_return_reg(FlatPtr value) { rax = value; }
 #endif
-    }
 
     void capture_syscall_params(FlatPtr& function, FlatPtr& arg1, FlatPtr& arg2, FlatPtr& arg3, FlatPtr& arg4) const
     {
@@ -120,24 +114,6 @@ struct [[gnu::packed]] RegisterState {
         arg4 = rsi;
 #endif
     }
-
-    void set_ip_reg(FlatPtr value)
-    {
-#if ARCH(I386)
-        eip = value;
-#else
-        rip = value;
-#endif
-    }
-
-    void set_return_reg(FlatPtr value)
-    {
-#if ARCH(I386)
-        eax = value;
-#else
-        rax = value;
-#endif
-    }
 };
 
 #if ARCH(I386)
diff --git a/Kernel/Arch/x86/common/SafeMem.cpp b/Kernel/Arch/x86/common/SafeMem.cpp
index 9fb7208ad3..36824714f8 100644
--- a/Kernel/Arch/x86/common/SafeMem.cpp
+++ b/Kernel/Arch/x86/common/SafeMem.cpp
@@ -299,13 +299,8 @@ bool handle_safe_access_fault(RegisterState& regs, FlatPtr fault_address)
         else
             return false;
 
-#if ARCH(I386)
-        regs.eip = ip;
-        regs.edx = fault_address;
-#else
-        regs.rip = ip;
-        regs.rdx = fault_address;
-#endif
+        regs.set_ip(ip);
+        regs.set_dx(fault_address);
         return true;
     }
     if (ip >= (FlatPtr)&start_of_safemem_atomic_text && ip < (FlatPtr)&end_of_safemem_atomic_text) {
@@ -325,13 +320,8 @@ bool handle_safe_access_fault(RegisterState& regs, FlatPtr fault_address)
         else
             return false;
 
-#if ARCH(I386)
-        regs.eip = ip;
-        regs.edx = 1;
-#else
-        regs.rip = ip;
-        regs.rdx = 1;
-#endif
+        regs.set_ip(ip);
+        regs.set_dx(1);
         return true;
     }
     return false;
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index f197cb4f92..61143fd994 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -195,11 +195,10 @@ RefPtr<Process> Process::create_kernel_process(RefPtr<Thread>& first_thread, Str
     auto process = Process::create(first_thread, move(name), (uid_t)0, (gid_t)0, ProcessID(0), true);
     if (!first_thread || !process)
         return {};
+    first_thread->regs().set_ip((FlatPtr)entry);
 #if ARCH(I386)
-    first_thread->regs().eip = (FlatPtr)entry;
     first_thread->regs().esp = FlatPtr(entry_data); // entry function argument is expected to be in regs.esp
 #else
-    first_thread->regs().rip = (FlatPtr)entry;
     first_thread->regs().rdi = FlatPtr(entry_data); // entry function argument is expected to be in regs.rdi
 #endif
 
@@ -769,13 +768,8 @@ RefPtr<Thread> Process::create_kernel_thread(void (*entry)(void*), void* entry_d
         thread->detach();
 
     auto& regs = thread->regs();
-#if ARCH(I386)
-    regs.eip = (FlatPtr)entry;
-    regs.esp = FlatPtr(entry_data); // entry function argument is expected to be in regs.rsp
-#else
-    regs.rip = (FlatPtr)entry;
-    regs.rsp = FlatPtr(entry_data); // entry function argument is expected to be in regs.rsp
-#endif
+    regs.set_ip((FlatPtr)entry);
+    regs.set_sp((FlatPtr)entry_data); // entry function argument is expected to be in the SP register
 
     ScopedSpinLock lock(g_scheduler_lock);
     thread->set_state(Thread::State::Runnable);
diff --git a/Kernel/Syscalls/thread.cpp b/Kernel/Syscalls/thread.cpp
index e3c3ff9e07..ec4b567f03 100644
--- a/Kernel/Syscalls/thread.cpp
+++ b/Kernel/Syscalls/thread.cpp
@@ -60,14 +60,10 @@ KResultOr<FlatPtr> Process::sys$create_thread(void* (*entry)(void*), Userspace<c
         thread->detach();
 
     auto& regs = thread->regs();
-#if ARCH(I386)
-    regs.eip = (FlatPtr)entry;
-    regs.eflags = 0x0202;
-    regs.esp = user_sp.value();
-#else
-    regs.rip = (FlatPtr)entry;
-    regs.rflags = 0x0202;
-    regs.rsp = user_sp.value();
+    regs.set_ip((FlatPtr)entry);
+    regs.set_flags(0x0202);
+    regs.set_sp(user_sp.value());
+#if ARCH(X86_64)
     regs.rdi = params.rdi;
     regs.rsi = params.rsi;
     regs.rdx = params.rdx;
diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index 06954a485a..2408dfac5c 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -86,10 +86,10 @@ Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Memory::Region> ker
 
     reset_fpu_state();
 
-#if ARCH(I386)
     // Only IF is set when a process boots.
-    m_regs.eflags = 0x0202;
+    m_regs.set_flags(0x0202);
 
+#if ARCH(I386)
     if (m_process->is_kernel_process()) {
         m_regs.cs = GDT_SELECTOR_CODE0;
         m_regs.ds = GDT_SELECTOR_DATA0;
@@ -106,9 +106,6 @@ Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Memory::Region> ker
         m_regs.gs = GDT_SELECTOR_TLS | 3;
     }
 #else
-    // Only IF is set when a process boots.
-    m_regs.rflags = 0x0202;
-
     if (m_process->is_kernel_process())
         m_regs.cs = GDT_SELECTOR_CODE0;
     else
@@ -121,20 +118,15 @@ Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Memory::Region> ker
     m_kernel_stack_top = m_kernel_stack_region->vaddr().offset(default_kernel_stack_size).get() & ~(FlatPtr)0x7u;
 
     if (m_process->is_kernel_process()) {
-#if ARCH(I386)
-        m_regs.esp = m_regs.esp0 = m_kernel_stack_top;
-#else
-        m_regs.rsp = m_regs.rsp0 = m_kernel_stack_top;
-#endif
+        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().
 #if ARCH(I386)
         m_regs.ss0 = GDT_SELECTOR_DATA0;
-        m_regs.esp0 = m_kernel_stack_top;
-#else
-        m_regs.rsp0 = m_kernel_stack_top;
 #endif
+        m_regs.set_sp0(m_kernel_stack_top);
     }
 
     // We need to add another reference if we could successfully create
@@ -938,21 +930,12 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
     m_have_any_unmasked_pending_signals.store(m_pending_signals & ~m_signal_mask, AK::memory_order_release);
 
     auto setup_stack = [&](RegisterState& state) {
-#if ARCH(I386)
-        FlatPtr stack = state.userspace_esp;
-        FlatPtr old_esp = stack;
-        FlatPtr ret_eip = state.eip;
-        FlatPtr ret_eflags = state.eflags;
-
-        dbgln_if(SIGNAL_DEBUG, "Setting up user stack to return to EIP {:p}, ESP {:p}", ret_eip, old_esp);
-#elif ARCH(X86_64)
-        FlatPtr stack = state.userspace_rsp;
-        FlatPtr old_rsp = stack;
-        FlatPtr ret_rip = state.rip;
-        FlatPtr ret_rflags = state.rflags;
-
-        dbgln_if(SIGNAL_DEBUG, "Setting up user stack to return to RIP {:p}, RSP {:p}", ret_rip, old_rsp);
-#endif
+        FlatPtr stack = state.userspace_sp();
+        FlatPtr old_sp = stack;
+        FlatPtr ret_ip = state.ip();
+        FlatPtr ret_flags = state.flags();
+
+        dbgln_if(SIGNAL_DEBUG, "Setting up user stack to return to IP {:p}, SP {:p}", ret_ip, old_sp);
 
 #if ARCH(I386)
         // Align the stack to 16 bytes.
@@ -963,14 +946,14 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
         FlatPtr stack_alignment = (stack - 8) % 16;
         stack -= stack_alignment;
 
-        push_value_on_user_stack(stack, ret_eflags);
+        push_value_on_user_stack(stack, ret_flags);
 
-        push_value_on_user_stack(stack, ret_eip);
+        push_value_on_user_stack(stack, ret_ip);
         push_value_on_user_stack(stack, state.eax);
         push_value_on_user_stack(stack, state.ecx);
         push_value_on_user_stack(stack, state.edx);
         push_value_on_user_stack(stack, state.ebx);
-        push_value_on_user_stack(stack, old_esp);
+        push_value_on_user_stack(stack, old_sp);
         push_value_on_user_stack(stack, state.ebp);
         push_value_on_user_stack(stack, state.esi);
         push_value_on_user_stack(stack, state.edi);
@@ -984,9 +967,9 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
         FlatPtr stack_alignment = stack % 16;
         stack -= 128 + stack_alignment;
 
-        push_value_on_user_stack(stack, ret_rflags);
+        push_value_on_user_stack(stack, ret_flags);
 
-        push_value_on_user_stack(stack, ret_rip);
+        push_value_on_user_stack(stack, ret_ip);
         push_value_on_user_stack(stack, state.r15);
         push_value_on_user_stack(stack, state.r14);
         push_value_on_user_stack(stack, state.r13);
@@ -999,7 +982,7 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
         push_value_on_user_stack(stack, state.rcx);
         push_value_on_user_stack(stack, state.rdx);
         push_value_on_user_stack(stack, state.rbx);
-        push_value_on_user_stack(stack, old_rsp);
+        push_value_on_user_stack(stack, old_sp);
         push_value_on_user_stack(stack, state.rbp);
         push_value_on_user_stack(stack, state.rsi);
         push_value_on_user_stack(stack, state.rdi);
@@ -1014,11 +997,7 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
 
         // We write back the adjusted stack value into the register state.
         // We have to do this because we can't just pass around a reference to a packed field, as it's UB.
-#if ARCH(I386)
-        state.userspace_esp = stack;
-#else
-        state.userspace_rsp = stack;
-#endif
+        state.set_userspace_sp(stack);
 
         VERIFY((stack % 16) == 0);
     };
@@ -1030,7 +1009,7 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
     auto& regs = get_register_dump_from_stack();
     setup_stack(regs);
     auto signal_trampoline_addr = process.signal_trampoline().get();
-    regs.set_ip_reg(signal_trampoline_addr);
+    regs.set_ip(signal_trampoline_addr);
 
     dbgln_if(SIGNAL_DEBUG, "Thread in state '{}' has been primed with signal handler {:#04x}:{:p} to deliver {}", state_string(), m_regs.cs, m_regs.ip(), signal);
 
diff --git a/Kernel/Thread.h b/Kernel/Thread.h
index c78c13b6d0..602058b4da 100644
--- a/Kernel/Thread.h
+++ b/Kernel/Thread.h
@@ -105,11 +105,23 @@ struct ThreadRegisters {
     FlatPtr rsp0;
 #endif
     FlatPtr cs;
+
 #if ARCH(I386)
     FlatPtr eflags;
+    FlatPtr flags() const { return eflags; }
+    void set_flags(FlatPtr value) { eflags = value; }
+    void set_sp(FlatPtr value) { esp = value; }
+    void set_sp0(FlatPtr value) { esp0 = value; }
+    void set_ip(FlatPtr value) { eip = value; }
 #else
     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