Kernel: Make PIT reserve its IRQ

PIT did not reserve IRQ leading to kernel panic if it was being
initialized.

kernel/arch/i686/Signal.S

@@ -7,22 +7,26 @@
 
 .global signal_trampoline
 signal_trampoline:
-	ud2
-
 	pushl %ebp
 	movl %esp, %ebp
-	subl $8, %esp
 
 	pusha
 
 	movl 40(%esp), %edi
 	movl 36(%esp), %eax
 
+	// align stack to 16 bytes
+	movl %esp, %ebx
+	andl $0x0F, %ebx
+	subl %ebx, %esp
+
 	subl $12, %esp
 	pushl %edi
 	call *%eax
 	addl $16, %esp
 
+	// restore stack
+	addl %ebx, %esp
 	popa
 
 	leave

kernel/arch/i686/boot.S

@@ -82,9 +82,18 @@ boot_pdpt:
 boot_pd:
 	.set i, 0
 	.rept 512
-		.long i + (PG_PAGE_SIZE | PG_READ_WRITE | PG_PRESENT)
+		.long V2P(boot_pts) + i + (PG_READ_WRITE | PG_PRESENT)
 		.long 0
-		.set i, i + 0x200000
+		.set i, i + 0x1000
+	.endr
+boot_pts:
+	.set i, 0
+	.rept 512
+		.rept 512
+			.long i + (PG_READ_WRITE | PG_PRESENT)
+			.long 0
+			.set i, i + 0x1000
+		.endr
 	.endr
 
 boot_gdt:

kernel/arch/x86_64/Signal.S

@@ -23,12 +23,18 @@ signal_trampoline:
 	pushq %r14
 	pushq %r15
 
-	// This is 16 byte aligned
-
 	movq 128(%rsp), %rdi
 	movq 120(%rsp), %rax
+
+	// align stack to 16 bytes
+	movq %rsp, %rbx
+	andq $0x0F, %rbx
+	subq %rbx, %rsp
+
 	call *%rax
 
+	// restore stack
+	addq %rbx, %rsp
 	popq %r15
 	popq %r14
 	popq %r13

kernel/include/kernel/ACPI/AML/Buffer.h

@@ -43,7 +43,7 @@ namespace Kernel::ACPI::AML
 			if (!buffer_size.has_value())
 				return ParseResult::Failure;
 
-			uint32_t actual_buffer_size = BAN::Math::max(buffer_size.value(), buffer_context.aml_data.size());
+			uint32_t actual_buffer_size = BAN::Math::max<uint32_t>(buffer_size.value(), buffer_context.aml_data.size());
 
 			auto buffer = MUST(BAN::RefPtr<Buffer>::create());
 			MUST(buffer->buffer.resize(actual_buffer_size, 0));

kernel/include/kernel/Lock/Mutex.h

@@ -103,6 +103,7 @@ namespace Kernel
 				ASSERT(m_lock_depth == 0);
 			}
 			m_lock_depth++;
+			return true;
 		}
 
 		void unlock()

kernel/include/kernel/Thread.h

@@ -94,7 +94,7 @@ namespace Kernel
 
 	private:
 		static constexpr size_t		m_kernel_stack_size		= PAGE_SIZE * 64;
-		static constexpr size_t		m_userspace_stack_size	= PAGE_SIZE * 4;
+		static constexpr size_t		m_userspace_stack_size	= PAGE_SIZE * 64;
 		BAN::UniqPtr<VirtualRange>	m_kernel_stack;
 		BAN::UniqPtr<VirtualRange>	m_userspace_stack;
 		const pid_t					m_tid				{ 0 };

kernel/kernel/ACPI/ACPI.cpp

@@ -19,10 +19,10 @@
 namespace Kernel::ACPI
 {
 
-
 	static uint32_t* s_global_lock { nullptr };
 
 	// https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html#global-lock
+#if ARCH(x86_64)
 asm(R"(
 .global acpi_acquire_global_lock
 acpi_acquire_global_lock:
@@ -54,6 +54,41 @@ acpi_release_global_lock:
 
 	ret
 )");
+#elif ARCH(i686)
+asm(R"(
+.global acpi_acquire_global_lock
+acpi_acquire_global_lock:
+	movl 4(%esp), %ecx
+	movl (%ecx), %edx
+	andl $(~1), %edx
+	btsl $1, %edx
+	adcl $0, %edx
+
+	lock cmpxchgl %edx, (%ecx)
+	jnz acpi_acquire_global_lock
+
+	cmpb $3, %dl
+	sbbl %eax, %eax
+	negl %eax
+
+	ret
+
+.global acpi_release_global_lock
+acpi_release_global_lock:
+	movl 4(%esp), %ecx
+	movl (%ecx), %eax
+	movl %eax, %edx
+
+	andl $(~3), %edx
+
+	lock cmpxchgl %edx, (%ecx)
+	jnz acpi_release_global_lock
+
+	andl $1, %eax
+
+	ret
+)");
+#endif
 
 	// returns true if lock was acquired successfully
 	extern "C" bool acpi_acquire_global_lock(uint32_t* lock);

kernel/kernel/APIC.cpp

@@ -247,6 +247,13 @@ namespace Kernel
 		uint8_t bsp_id = Kernel::Processor::current_id();
 		dprintln("BSP lapic id: {}", bsp_id);
 
+		if (m_processors.size() == 1)
+		{
+			dprintln("Only one processor, skipping AP initialization");
+			*g_ap_startup_done = 1;
+			return;
+		}
+
 		for (auto& processor : m_processors)
 		{
 			if (processor.apic_id == bsp_id)

kernel/kernel/Thread.cpp

@@ -335,7 +335,9 @@ namespace Kernel
 		else if (signal_handler != (vaddr_t)SIG_DFL)
 		{
 			// call userspace signal handlers
+#if ARCH(x86_64)
 			interrupt_stack.sp -= 128; // skip possible red-zone
+#endif
 			write_to_stack(interrupt_stack.sp, interrupt_stack.ip);
 			write_to_stack(interrupt_stack.sp, signal);
 			write_to_stack(interrupt_stack.sp, signal_handler);

kernel/kernel/Timer/PIT.cpp

@@ -47,6 +47,7 @@ namespace Kernel
 		IO::outb(TIMER0_CTL, (timer_reload >> 0) & 0xff);
 		IO::outb(TIMER0_CTL, (timer_reload >> 8) & 0xff);
 
+		MUST(InterruptController::get().reserve_irq(PIT_IRQ));
 		set_irq(PIT_IRQ);
 		enable_interrupt();
 	}