Kernel: start work on higher half kernel

kernel/CMakeLists.txt

@@ -125,7 +125,7 @@ if(ENABLE_KERNEL_UBSAN)
 endif()
 
 if("${BANAN_ARCH}" STREQUAL "x86_64")
-	target_compile_options(kernel PUBLIC -mcmodel=large -mno-red-zone -mno-mmx)
+	target_compile_options(kernel PUBLIC -mcmodel=kernel -mno-red-zone -mno-mmx)
 	target_link_options(kernel PUBLIC LINKER:-z,max-page-size=4096)
 	target_link_options(kernel PUBLIC LINKER:-T,${CMAKE_CURRENT_SOURCE_DIR}/arch/x86_64/linker.ld)
 elseif("${BANAN_ARCH}" STREQUAL "i386")

kernel/arch/x86_64/IDT.cpp

@@ -101,6 +101,9 @@ namespace IDT
 
 	extern "C" void cpp_isr_handler(uint64_t isr, uint64_t error, const Registers* regs)
 	{
+		pid_t tid = Kernel::Scheduler::current_tid();
+		pid_t pid = tid ? Kernel::Process::current().pid() : 0;
+
 		dwarnln(
 			"{} (error code: 0x{16H}), pid {}, tid {}\r\n"
 			"Register dump\r\n"
@@ -108,14 +111,14 @@ namespace IDT
 			"rsp=0x{16H}, rbp=0x{16H}, rdi=0x{16H}, rsi=0x{16H}\r\n"
 			"rip=0x{16H}, rflags=0x{16H}\r\n"
 			"cr0=0x{16H}, cr2=0x{16H}, cr3=0x{16H}, cr4=0x{16H}",
-			isr_exceptions[isr], error, Kernel::Process::current().pid(), Kernel::Thread::current().tid(),
+			isr_exceptions[isr], error, pid, tid,
 			regs->rax, regs->rbx, regs->rcx, regs->rdx,
 			regs->rsp, regs->rbp, regs->rdi, regs->rsi,
 			regs->rip, regs->rflags,
 			regs->cr0, regs->cr2, regs->cr3, regs->cr4
 		);
 
-		if (Kernel::Thread::current().is_userspace() && !Kernel::Thread::current().is_in_syscall())
+		if (tid && Kernel::Thread::current().is_userspace() && !Kernel::Thread::current().is_in_syscall())
 		{
 			auto message = BAN::String::formatted("{}, aborting\n", isr_exceptions[isr]);
 			(void)Kernel::Process::current().write(STDERR_FILENO, message.data(), message.size());

kernel/arch/x86_64/PageTable.cpp

@@ -12,6 +12,7 @@
 		kfree(s);							\
 	} while (false)
 
+extern uint8_t g_kernel_start[];
 extern uint8_t g_kernel_end[];
 
 namespace Kernel
@@ -20,6 +21,20 @@ namespace Kernel
 	static PageTable* s_kernel = nullptr;
 	static PageTable* s_current = nullptr;
 
+	static inline bool is_canonical(uintptr_t addr)
+	{
+		static constexpr uintptr_t mask = 0xFFFF800000000000;
+		addr &= mask;
+		return addr == mask || addr == 0;
+	}
+
+	static inline void uncanonicalize(uintptr_t& addr)
+	{
+		static constexpr uintptr_t mask = 0xFFFF800000000000;
+		addr &= mask;
+		ASSERT(addr == mask || addr == 0);
+	}
+
 	void PageTable::initialize()
 	{
 		ASSERT(s_kernel == nullptr);
@@ -56,7 +71,7 @@ namespace Kernel
 
 		// Identity map 4 KiB -> kernel end. We don't map the first page since nullptr derefs should
 		// page fault. Also there isn't anything useful in that memory.
-		identity_map_range(PAGE_SIZE, (uintptr_t)g_kernel_end, Flags::ReadWrite | Flags::Present);
+		identity_map_range((uintptr_t)g_kernel_start, (uintptr_t)(g_kernel_end - g_kernel_start), Flags::ReadWrite | Flags::Present);
 	}
 
 	BAN::ErrorOr<PageTable*> PageTable::create_userspace()
@@ -169,7 +184,7 @@ namespace Kernel
 	{
 		LockGuard _(m_lock);
 
-		ASSERT((address >> 48) == 0);
+		uncanonicalize(address);
 
 		address &= PAGE_ADDR_MASK;
 
@@ -212,8 +227,8 @@ namespace Kernel
 	{
 		LockGuard _(m_lock);
 
-		ASSERT((paddr >> 48) == 0);
+		ASSERT(is_canonical(paddr));
-		ASSERT((vaddr >> 48) == 0);
+		uncanonicalize(vaddr);
 
 		ASSERT(paddr % PAGE_SIZE == 0);
 		ASSERT(vaddr % PAGE_SIZE == 0);;
@@ -257,7 +272,7 @@ namespace Kernel
 	{
 		LockGuard _(m_lock);
 
-		ASSERT((address >> 48) == 0);
+		uncanonicalize(address);
 		ASSERT(address % PAGE_SIZE == 0);
 
 		uint64_t pml4e = (address >> 39) & 0x1FF;

kernel/arch/x86_64/boot.S

@@ -10,6 +10,9 @@
 .set PG_READ_WRITE,	1<<1
 .set PG_PAGE_SIZE,	1<<7
 
+#define KERNEL_OFFSET 0xFFFFFFFF80000000
+#define V2P(vaddr) ((vaddr) - KERNEL_OFFSET)
+
 .code32
 
 # Multiboot header
@@ -49,16 +52,23 @@
 # Identity map first GiB
 .align 4096
 boot_pml4:
-	.quad boot_pdpt + (PG_READ_WRITE | PG_PRESENT)
+	.quad V2P(boot_pdpt_lo) + (PG_READ_WRITE | PG_PRESENT)
+	.rept 510
+		.quad 0
+	.endr
+	.quad V2P(boot_pdpt_hi) + (PG_READ_WRITE | PG_PRESENT)
+boot_pdpt_lo:
+	.quad V2P(boot_pd) + (PG_READ_WRITE | PG_PRESENT)
 	.rept 511
 		.quad 0
 	.endr
-boot_pdpt:
+boot_pdpt_hi:
-	.quad boot_pd + (PG_READ_WRITE | PG_PRESENT)
+	.rept 510
-	.rept 511
 		.quad 0
-	.endr
+	.endr	
-boot_pd:
+	.quad V2P(boot_pd) + (PG_READ_WRITE | PG_PRESENT)
+	.quad 0
+boot_pd: # 1 GiB
 	.set i, 0
 	.rept 512
 		.quad i + (PG_PAGE_SIZE | PG_READ_WRITE | PG_PRESENT)
@@ -71,7 +81,7 @@ boot_gdt:
 	.quad 0x00AF92000000FFFF # kernel data
 boot_gdtr:
 	.short . - boot_gdt - 1
-	.quad boot_gdt
+	.quad V2P(boot_gdt)
 
 has_cpuid:
 	pushfl
@@ -110,11 +120,11 @@ check_requirements:
 copy_kernel_commandline:
 	pushl %esi
 	pushl %edi
-	movl g_multiboot_info, %esi
+	movl V2P(g_multiboot_info), %esi
 	addl $16, %esi
 	movl (%esi), %esi
 	movl $1024, %ecx
-	movl $g_kernel_cmdline, %edi
+	movl $V2P(g_kernel_cmdline), %edi
 	rep movsl
 	popl %edi
 	popl %esi
@@ -143,7 +153,7 @@ initialize_paging:
 	wrmsr
 
 	# set address of paging structures
-	movl $boot_pml4, %ecx
+	movl $V2P(boot_pml4), %ecx
 	movl %ecx, %cr3
 
 	# enable paging
@@ -157,9 +167,9 @@ initialize_paging:
 .type _start, @function
 _start:
 	# Initialize stack and multiboot info
-	movl $g_boot_stack_top, %esp
+	movl $V2P(g_boot_stack_top), %esp
-	movl %eax, g_multiboot_magic
+	movl %eax, V2P(g_multiboot_magic)
-	movl %ebx, g_multiboot_info
+	movl %ebx, V2P(g_multiboot_info)
 
 	call copy_kernel_commandline
 	call check_requirements
@@ -168,8 +178,8 @@ _start:
 	call initialize_paging
 
 	# flush gdt and jump to 64 bit
-	lgdt boot_gdtr
+	lgdt V2P(boot_gdtr)
-	ljmpl $0x08, $long_mode
+	ljmpl $0x08, $V2P(long_mode)
 
 .code64
 long_mode:
@@ -183,6 +193,13 @@ long_mode:
 	movw %ax, %fs
 	movw %ax, %gs
 
+	# jump to higher half
+	movq $g_boot_stack_top, %rsp
+	movabsq $higher_half, %rcx
+	jmp *%rcx
+
+higher_half:
+
 	# call global constuctors
 	call _init
 

kernel/arch/x86_64/linker.ld

@@ -1,24 +1,26 @@
 ENTRY (_start)
 
+KERNEL_OFFSET = 0xFFFFFFFF80000000;
+
 SECTIONS
 {
-	. = 0x00100000;
+	. = 0x00100000 + KERNEL_OFFSET;
 
 	g_kernel_start = .;
-	.text BLOCK(4K) : ALIGN(4K)
+	.text ALIGN(4K) : AT(ADDR(.text) - KERNEL_OFFSET)
 	{
 		*(.multiboot)
 		*(.text)
 	}
-	.rodata BLOCK(4K) : ALIGN(4K)
+	.rodata ALIGN(4K) : AT(ADDR(.rodata) - KERNEL_OFFSET)
 	{
 		*(.rodata.*)
 	}
-	.data BLOCK(4K) : ALIGN(4K)
+	.data ALIGN(4K) : AT(ADDR(.data) - KERNEL_OFFSET)
 	{
 		*(.data)
 	}
-	.bss BLOCK(4K) : ALIGN(4K)
+	.bss ALIGN(4K) : AT(ADDR(.bss) - KERNEL_OFFSET)
 	{
 		*(COMMON)
 		*(.bss)