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#include "loader_efi.h"
static bool validate_image(Elf64_Ehdr *ehdr);
static size_t image_size(struct system_image *image);
static enum page_type get_page_type(Elf64_Phdr *phdr);
struct system_image *system_image_open(CHAR16 *path)
{
EFI_STATUS status;
EFI_FILE_PROTOCOL *root;
EFI_FILE_PROTOCOL *file;
struct system_image *image = NULL;
status = e_system_partition->OpenVolume(e_system_partition, &root);
if (EFI_ERROR(status))
{
Print(L"failed opening system partition root: %r\r\n", status);
return NULL;
}
status = root->Open(root, &file, path, EFI_FILE_MODE_READ, 0);
if (EFI_ERROR(status))
{
Print(L"failed opening image file %s: %r\r\n", path, status);
return NULL;
}
image = efi_allocate(sizeof(*image));
if (!image)
{
Print(L"failed allocating image data: %r\r\n", e_last_error);
goto failure;
}
image->file = file;
UINTN ehdr_size = sizeof(image->ehdr);
status = file->Read(file, &ehdr_size, &image->ehdr);
if (EFI_ERROR(status))
{
Print(L"failed reading image file %s: %r\r\n", path, status);
goto failure;
}
if (!validate_image(&image->ehdr))
{
Print(L"failed validating image file %s: %r\r\n", path, status);
goto failure;
}
UINTN phdrs_size = image->ehdr.e_phentsize * image->ehdr.e_phnum;
image->phdrs = efi_allocate(phdrs_size);
if (!image->phdrs)
{
Print(L"failed allocating segment data: %r", e_last_error);
goto failure;
}
status = file->Read(file, &phdrs_size, image->phdrs);
if (EFI_ERROR(status))
{
Print(L"failed reading segment data: %r", status);
goto failure;
}
return image;
failure:
file->Close(file);
return NULL;
}
bool system_image_load(struct system_image *image)
{
image->buffer = system_allocate(image_size(image));
if (image->buffer.type != SYSTEM_MEMORY)
{
return false;
}
e_bs->SetMem((VOID *)image->buffer.base, image->buffer.size, 0);
Elf64_Ehdr *ehdr = &image->ehdr;
Elf64_Phdr *phdrs = image->phdrs;
Print(L"found %d segments in image\r\n", ehdr->e_phnum);
EFI_STATUS status = EFI_SUCCESS;
for (UINTN i = 0; i < ehdr->e_phnum && !EFI_ERROR(status); i++)
{
switch (phdrs[i].p_type)
{
case PT_LOAD:
Print(L"loadable segment %16.0lx at offset %x of %d bytes\r\n",
phdrs[i].p_vaddr,
phdrs[i].p_offset,
phdrs[i].p_memsz);
void *segment = (void *)(image->buffer.base + phdrs[i].p_paddr);
UINTN segment_size = phdrs[i].p_filesz;
image->file->SetPosition(image->file, phdrs[i].p_offset);
status = image->file->Read(image->file, &segment_size, segment);
break;
default:
continue;
}
}
if (EFI_ERROR(status))
{
Print(L"failure reading segment from file: %r\r\n", status);
return false;
}
return true;
}
void system_image_map(struct system_image *image)
{
Elf64_Ehdr *ehdr = &image->ehdr;
Elf64_Phdr *phdrs = image->phdrs;
for (int i = 0; i < ehdr->e_phnum; i++)
{
if (phdrs[i].p_type == PT_LOAD)
{
void *virt_begin = (void *)phdrs[i].p_vaddr;
uint64_t phys_begin = image->buffer.base + phdrs[i].p_paddr;
size_t size = phdrs[i].p_memsz;
Print(L"mapping segment %16.0lx to %16.0lx %d bytes\r\n",
virt_begin,
phys_begin,
size);
paging_map_pages(virt_begin,
phys_begin,
get_page_type(&phdrs[i]),
size);
}
}
}
static bool validate_image(Elf64_Ehdr *ehdr)
{
if (ehdr->e_ident[EI_MAG0] != ELFMAG0 ||
ehdr->e_ident[EI_MAG1] != ELFMAG1 ||
ehdr->e_ident[EI_MAG2] != ELFMAG2 ||
ehdr->e_ident[EI_MAG3] != ELFMAG3 ||
ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
ehdr->e_ident[EI_DATA] != ELFDATA2LSB ||
ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
ehdr->e_machine != EM_X86_64)
{
Print(L"invalid image format\r\n");
return false;
}
Print(L"elf x64 image detected\r\n");
return true;
}
static size_t image_size(struct system_image *image)
{
size_t size = 0;
Elf64_Phdr *phdrs = image->phdrs;
for (int i = 0; i < image->ehdr.e_phnum; i++)
{
if (phdrs[i].p_type != PT_LOAD)
{
continue;
}
if (phdrs[i].p_paddr + phdrs[i].p_memsz > size)
{
size = phdrs[i].p_paddr + phdrs[i].p_memsz;
if (phdrs[i].p_align > 1)
{
size = (size + phdrs[i].p_align - 1) & ~(phdrs[i].p_align - 1);
}
}
}
return size;
}
static enum page_type get_page_type(Elf64_Phdr *phdr)
{
switch (phdr->p_flags)
{
case (PF_R|PF_X):
return CODE_PAGE_TYPE;
case (PF_R):
return RODATA_PAGE_TYPE;
case (PF_R|PF_W):
return DATA_PAGE_TYPE;
}
return INVALID_PAGE_TYPE;
}
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