/* Copyright (C) 2021,2022 fef <owo@fef.moe>.  All rights reserved. */

#include <arch/cpufunc.h>
#include <arch/page.h>
#include <arch/segment.h>
#include <arch/trap.h>

#include <gay/cdefs.h>
#include <gay/kprintf.h>
#include <gay/ktrace.h>
#include <gay/systm.h>
#include <gay/types.h>
#include <gay/vm/page.h>

#include <string.h>

/*
 * Initial Page Directory Pointer Table and Page Map Level 4 Table for the
 * assembly startup routine (see setup64.S).  Used for statically mapping the
 * lowest 2 GB of physical memory into the -2 GB virtual area.
 */
__asmlink x86_pdpt_t _pdpt0;
__asmlink x86_pml4t_t _pml4t;

void x86_isr_page_fault(trap_frame_t *frame, u32 error_code)
{
	void *address;
	__asm__ volatile(
"	mov	%%cr2,	%0	\n"
	: "=r"(address)
	:
	);

	const char *space;
	if (error_code & X86_PF_USER)
		space = "user";
	else
		space = "kernel";

	const char *rwx;
	if (error_code & X86_PF_WRITE)
		rwx = "write to";
	else if (error_code & X86_PF_INSTR)
		rwx = "exec at";
	else
		rwx = "read from";

	const char *present;
	if (error_code & X86_PF_PRESENT)
		present = "";
	else
		present = " non-mapped";

	kprintf("\n##########  B O N K  ##########\n");
	kprintf("Illegal %s %s%s address %p!\n", space, rwx, present, address);
	print_regs(frame);
	/* print a stack trace if this came from kernel space */
	if (frame->hw_frame.cs == X86_64_KERN_CS)
		ktrace_print_from((void *)frame->rbp);
	panic_notrace("Page fault");
}

vm_paddr_t vtophys(void *virt)
{
	x86_pml4te_t *pml4te = X86_PML4TE(virt);
	if (!pml4te->flags.present)
		return (vm_paddr_t)-1;

	x86_pdpte_t *pdpte = X86_PDPTE(virt);
	if (!pdpte->flags.present)
		return (vm_paddr_t)-1;
	if (pdpte->flags.huge) {
		vm_paddr_t phys_base = pdpte->val & X86_PMAP_MASK;
		return phys_base + ((vm_paddr_t)virt % (1 << X86_PDPT_SHIFT));
	}

	x86_pdte_t *pdte = X86_PDTE(virt);
	if (!pdte->flags.present)
		return (vm_paddr_t)-1;
	if (pdte->flags.huge) {
		vm_paddr_t phys_base = pdte->val & X86_PMAP_MASK;
		return phys_base + ((vm_paddr_t)virt % (1 << X86_PDT_SHIFT));
	}

	x86_pte_t *pte = X86_PTE(virt);
	if (!pte->flags.present)
		return (vm_paddr_t)-1;
	vm_paddr_t phys_base = pte->val & X86_PMAP_MASK;
	return phys_base + ((vm_paddr_t)virt % (1 << X86_PT_SHIFT));
}

void page_clear(vm_page_t page)
{
	register_t cpuflags = intr_disable();
	page_lock(page);
	u64 *dest = DMAP_START + (pg2pfn(page) << PAGE_SHIFT);
	usize nbyte = (usize)1 << (pga_order(page) + PAGE_SHIFT);
	memset64(dest, 0, nbyte);
	page_unlock(page);
	intr_restore(cpuflags);
}