loader.c

#include  <Uefi.h>
#include  <Library/UefiLib.h>
#include  <Library/UefiBootServicesTableLib.h>
#include  <Protocol/BlockIo.h>
#include  <Protocol/LoadedImage.h>
#include  <Protocol/SimpleFileSystem.h>
#include  <Library/DevicePathLib.h>
#include  <Guid/FileInfo.h>
#include  <Guid/Acpi.h>
#include  <Library/MemoryAllocationLib.h>
#include  <Library/BaseMemoryLib.h>
#include "elf.h"
#include "relocate.h"
#include "memory_map.h"
#include "graphic.h"
#include "structs.h"

void set_gdt(struct gdt *gdt,UINT32 type,UINT32 base,UINT32 lim);

EFI_STATUS
EFIAPI
UefiMain (
  IN EFI_HANDLE ImageHandle,
  IN EFI_SYSTEM_TABLE *SystemTable
  )
{
  EFI_STATUS Status;
  CHAR16 *KernelPath = L"\\kernel";
  CHAR16 *bmp_file = L"\\logo.bmp";
  EFI_PHYSICAL_ADDRESS BootParamAddr = 0x50000;
  EFI_PHYSICAL_ADDRESS KernelBaseAddr;

  RelocateELF(KernelPath, &KernelBaseAddr);
  
  Status =  gBS->AllocatePages(AllocateAddress,EfiLoaderData,1,&BootParamAddr);
  if(EFI_ERROR(Status)){
    Print(L"Can not allocate boot param address\n");
  }
  
  struct boot_param *boot_param = (struct boot_param *)BootParamAddr;
  boot_param->kernel_entry = (UINT64)KernelBaseAddr;
  
//途中省略

  boot_param->kernel_addr = KernelBaseAddr;
  Print(L"KernelAddress : %x\n",boot_param->kernel_addr);
  boot_param->bootstrap_gdt_desc.size = sizeof(struct gdt)*3;
  boot_param->bootstrap_gdt_desc.gdt_addr = (UINT64)boot_param->bootstrap_gdt;

  boot_param->bootstrap_gdt[0].limit = 0;
  boot_param->bootstrap_gdt[0].base1 = 0;
  boot_param->bootstrap_gdt[0].base2 = 0;
  boot_param->bootstrap_gdt[0].access_byte = 0;
  boot_param->bootstrap_gdt[0].flags = 0;
  boot_param->bootstrap_gdt[0].base3 = 0;

  set_gdt(&(boot_param->bootstrap_gdt[1]),STA_X|STA_R,0x0,0xffffffff);
  set_gdt(&(boot_param->bootstrap_gdt[2]),STA_W,0x0,0xffffffff);
  Print(L"BootStrap GDT Descriptor Address: %x\n",&(boot_param->bootstrap_gdt_desc));
  
  struct MemoryMap MemoryMap = {4096,NULL,4096,0,0,0};
  Status = gBS->AllocatePool(EfiLoaderData, MemoryMap.BufferSize, &MemoryMap.Buffer);
  if(EFI_ERROR(Status)){
    Print(L"Failed to allocate memory to get memory map\n");
    return Status;
  }
  Print(L"AllocatePool=%d\n",Status);
  Status = DrawBMP(bmp_file,&(boot_param->graphic_config));
  if(EFI_ERROR(Status)){
    Print(L"Failed to draw bitmap file %s\n",bmp_file);
  }
  gBS->GetMemoryMap(
            &MemoryMap.MapSize,
            (EFI_MEMORY_DESCRIPTOR*)MemoryMap.Buffer,
            &MemoryMap.MapKey,
            &MemoryMap.DescriptorSize,
            &MemoryMap.DescriptorVersion);
  
  Status = gBS->ExitBootServices(ImageHandle, MemoryMap.MapKey);
  if(EFI_ERROR(Status)){
    Print(L"Could not exit boot services : %r",Status);
  }
  asm("lgdt %0": : "m"(boot_param->bootstrap_gdt_desc));
  asm("push $0x08");
  asm("push %0": : "m"(boot_param->kernel_addr));
  asm("lretq");
  while(1);
}

void set_gdt(struct gdt *gdt,UINT32 type,UINT32 base,UINT32 lim){
  gdt->limit = (lim >> 12) & 0xFFFF;
  gdt->base1 = base & 0xFFFF;
  gdt->base2 = (base >> 16) & 0xFF;
  gdt->access_byte = 0x90 | type;
  gdt->flags = 0xC0 | ((lim >> 28) & 0xF);
  gdt->base3 = (base >> 24) & 0xFF;
}