/*
 * Copyright 2021-2022 Haiku, Inc. All rights reserved.
 * Released under the terms of the MIT License.
 */


#include <kernel.h>
#include <boot/platform.h>
#include <boot/stage2.h>
#include <boot/stdio.h>

#include "efi_platform.h"
#include "generic_mmu.h"
#include "mmu.h"
#include "serial.h"
#include "smp.h"


struct gdt_idt_descr {
        uint16  limit;
        void*   base;
} _PACKED;


extern "C" typedef void (*enter_kernel_t)(uint32_t, addr_t, addr_t, addr_t,
        struct gdt_idt_descr *);


// From entry.S
extern "C" void arch_enter_kernel(uint32_t pageDirectory, addr_t kernelArgs,
        addr_t kernelEntry, addr_t kernelStackTop, struct gdt_idt_descr *gdtDescriptor);

// From arch_mmu.cpp
extern void arch_mmu_init_gdt(gdt_idt_descr &bootGDTDescriptor);

extern void arch_mmu_post_efi_setup(size_t memoryMapSize,
        efi_memory_descriptor *memoryMap, size_t descriptorSize,
        uint32_t descriptorVersion);

extern uint32_t arch_mmu_generate_post_efi_page_tables(size_t memoryMapSize,
        efi_memory_descriptor *memoryMap, size_t descriptorSize,
        uint32_t descriptorVersion);


void
arch_convert_kernel_args(void)
{
        fix_address(gKernelArgs.ucode_data);
        fix_address(gKernelArgs.arch_args.apic);
        fix_address(gKernelArgs.arch_args.hpet);
}


void
arch_start_kernel(addr_t kernelEntry)
{
        gdt_idt_descr bootGDTDescriptor;
        arch_mmu_init_gdt(bootGDTDescriptor);

        // Copy entry.S trampoline to lower 1M
        enter_kernel_t enter_kernel = (enter_kernel_t)0xa000;
        memcpy((void *)enter_kernel, (void *)arch_enter_kernel, B_PAGE_SIZE);

        // Allocate virtual memory for kernel args
        struct kernel_args *kernelArgs = NULL;
        if (platform_allocate_region((void **)&kernelArgs,
                        sizeof(struct kernel_args), 0) != B_OK)
                panic("Failed to allocate kernel args.");

        addr_t virtKernelArgs;
        platform_bootloader_address_to_kernel_address((void*)kernelArgs,
                &virtKernelArgs);

        // Prepare to exit EFI boot services.
        // Read the memory map.
        // First call is to determine the buffer size.
        size_t memoryMapSize = 0;
        efi_memory_descriptor dummy;
        size_t mapKey;
        size_t descriptorSize;
        uint32_t descriptorVersion;
        if (kBootServices->GetMemoryMap(&memoryMapSize, &dummy, &mapKey,
                        &descriptorSize, &descriptorVersion) != EFI_BUFFER_TOO_SMALL) {
                panic("Unable to determine size of system memory map");
        }

        // Allocate a buffer twice as large as needed just in case it gets bigger
        // between calls to ExitBootServices.
        size_t actualMemoryMapSize = memoryMapSize * 2;
        efi_memory_descriptor *memoryMap
                = (efi_memory_descriptor *)kernel_args_malloc(actualMemoryMapSize);

        if (memoryMap == NULL)
                panic("Unable to allocate memory map.");

        // Read (and print) the memory map.
        memoryMapSize = actualMemoryMapSize;
        if (kBootServices->GetMemoryMap(&memoryMapSize, memoryMap, &mapKey,
                        &descriptorSize, &descriptorVersion) != EFI_SUCCESS) {
                panic("Unable to fetch system memory map.");
        }

        addr_t addr = (addr_t)memoryMap;
        dprintf("System provided memory map:\n");
        for (size_t i = 0; i < memoryMapSize / descriptorSize; i++) {
                efi_memory_descriptor *entry
                        = (efi_memory_descriptor *)(addr + i * descriptorSize);
                dprintf("  phys: 0x%08" PRIx64 "-0x%08" PRIx64
                        ", virt: 0x%08" PRIx64 "-0x%08" PRIx64
                        ", type: %s (%#x), attr: %#" PRIx64 "\n",
                        entry->PhysicalStart,
                        entry->PhysicalStart + entry->NumberOfPages * B_PAGE_SIZE,
                        entry->VirtualStart,
                        entry->VirtualStart + entry->NumberOfPages * B_PAGE_SIZE,
                        memory_region_type_str(entry->Type), entry->Type,
                        entry->Attribute);
        }

        // Generate page tables for use after ExitBootServices.
        uint32_t pageDirectory = arch_mmu_generate_post_efi_page_tables(
                memoryMapSize, memoryMap, descriptorSize, descriptorVersion);

        // Attempt to fetch the memory map and exit boot services.
        // This needs to be done in a loop, as ExitBootServices can change the
        // memory map.
        // Even better: Only GetMemoryMap and ExitBootServices can be called after
        // the first call to ExitBootServices, as the firmware is permitted to
        // partially exit. This is why twice as much space was allocated for the
        // memory map, as it's impossible to allocate more now.
        // A changing memory map shouldn't affect the generated page tables, as
        // they only needed to know about the maximum address, not any specific
        // entry.

        dprintf("Calling ExitBootServices. So long, EFI!\n");
        serial_disable();

        while (true) {
                if (kBootServices->ExitBootServices(kImage, mapKey) == EFI_SUCCESS) {
                        // Disconnect from EFI serial_io / stdio services
                        serial_kernel_handoff();
                        dprintf("Unhooked from EFI serial services\n");
                        break;
                }

                memoryMapSize = actualMemoryMapSize;
                if (kBootServices->GetMemoryMap(&memoryMapSize, memoryMap, &mapKey,
                                &descriptorSize, &descriptorVersion) != EFI_SUCCESS) {
                        panic("Unable to fetch system memory map.");
                }
        }

        // Update EFI, generate final kernel physical memory map, etc.
        arch_mmu_post_efi_setup(memoryMapSize, memoryMap,
                descriptorSize, descriptorVersion);

        // Re-init and activate serial in a horrific post-EFI landscape. Clowns roam the land freely.
        serial_init();
        serial_enable();

        // Copy final kernel args
        // This should be the last step before jumping to the kernel
        // as there are some fixups happening to kernel_args even in the last minute
        memcpy((void *)kernelArgs, &gKernelArgs, sizeof(struct kernel_args));

        smp_boot_other_cpus(pageDirectory, kernelEntry, virtKernelArgs);

        // Enter the kernel!
        dprintf("enter_kernel(pageDirectory: 0x%08x, kernelArgs: 0x%08x, "
                "kernelEntry: 0x%08x, sp: 0x%08x, bootGDTDescriptor: 0x%08x)\n",
                pageDirectory, (uint32_t)virtKernelArgs, (uint32_t)kernelEntry,
                (uint32_t)(gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size),
                (uint32_t)&bootGDTDescriptor);

        enter_kernel(pageDirectory, virtKernelArgs, kernelEntry,
                gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size,
                &bootGDTDescriptor);
}