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Remove support for compat kernel entry point #13

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Merged
kukrimate merged 1 commit into from
Aug 11, 2025
Merged

Remove support for compat kernel entry point #13

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2 changes: 1 addition & 1 deletion include/pe.h
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,6 @@ EFI_STATUS pe_memory_locate_sections(
const char *const section_names[],
PeSectionVector sections[]);

EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory);
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory);

EFI_STATUS pe_kernel_check_no_relocation(const void *base);
13 changes: 3 additions & 10 deletions linux.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,16 +112,9 @@ EFI_STATUS linux_exec(

log_wait();

if (entry_point > 0) {
EFI_IMAGE_ENTRY_POINT entry =
(EFI_IMAGE_ENTRY_POINT) ((const uint8_t *) parent_loaded_image->ImageBase + entry_point);
err = entry(parent_image, ST);
} else if (compat_entry_point > 0) {
/* Try calling the kernel compat entry point if one exists. */
EFI_IMAGE_ENTRY_POINT compat_entry =
(EFI_IMAGE_ENTRY_POINT) ((const uint8_t *) parent_loaded_image->ImageBase + compat_entry_point);
err = compat_entry(parent_image, ST);
}
EFI_IMAGE_ENTRY_POINT entry =
(EFI_IMAGE_ENTRY_POINT) ((const uint8_t *) parent_loaded_image->ImageBase + entry_point);
err = entry(parent_image, ST);

return log_error_status(err, "Error starting kernel image: %m");
}
71 changes: 4 additions & 67 deletions pe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -372,54 +372,7 @@ void pe_locate_sections(
sections);
}

static uint32_t get_compatibility_entry_address(const DosFileHeader *dos, const PeFileHeader *pe) {
/* The kernel may provide alternative PE entry points for different PE architectures. This allows
* booting a 64-bit kernel on 32-bit EFI that is otherwise running on a 64-bit CPU. The locations of any
* such compat entry points are located in a special PE section. */

assert(dos);
assert(pe);

static const char *const section_names[] = { ".compat", NULL };
PeSectionVector vector[1] = {};
pe_locate_sections(
(const PeSectionHeader *) ((const uint8_t *) dos + section_table_offset(dos, pe)),
pe->FileHeader.NumberOfSections,
section_names,
PTR_TO_SIZE(dos),
vector);

if (!PE_SECTION_VECTOR_IS_SET(vector)) /* not found */
return 0;

typedef struct {
uint8_t type;
uint8_t size;
uint16_t machine_type;
uint32_t entry_point;
} _packed_ LinuxPeCompat1;

size_t addr = vector[0].memory_offset, size = vector[0].memory_size;

while (size >= sizeof(LinuxPeCompat1) && addr % alignof(LinuxPeCompat1) == 0) {
const LinuxPeCompat1 *compat = (const LinuxPeCompat1 *) ((const uint8_t *) dos + addr);

if (compat->type == 0 || compat->size == 0 || compat->size > size)
break;

if (compat->type == 1 &&
compat->size >= sizeof(LinuxPeCompat1) &&
compat->machine_type == TARGET_MACHINE_TYPE)
return compat->entry_point;

addr += compat->size;
size -= compat->size;
}

return 0;
}

EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory) {
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory) {
assert(base);

const DosFileHeader *dos = (const DosFileHeader *) base;
Expand Down Expand Up @@ -450,32 +403,16 @@ EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t
if (pe->OptionalHeader.MajorImageVersion < 1)
return EFI_UNSUPPORTED;

if (pe->FileHeader.Machine == TARGET_MACHINE_TYPE) {
if (ret_entry_point)
*ret_entry_point = pe->OptionalHeader.AddressOfEntryPoint;
if (ret_compat_entry_point)
*ret_compat_entry_point = 0;
if (ret_image_base)
*ret_image_base = image_base;
if (ret_size_in_memory)
*ret_size_in_memory = size_in_memory;
return EFI_SUCCESS;
}

uint32_t compat_entry_point = get_compatibility_entry_address(dos, pe);
if (compat_entry_point == 0)
/* Image type not supported and no compat entry found. */
/* We do not support cross-architecture kernel loading. */
if (pe->FileHeader.Machine != TARGET_MACHINE_TYPE)
return EFI_UNSUPPORTED;

if (ret_entry_point)
*ret_entry_point = 0;
if (ret_compat_entry_point)
*ret_compat_entry_point = compat_entry_point;
*ret_entry_point = pe->OptionalHeader.AddressOfEntryPoint;
if (ret_image_base)
*ret_image_base = image_base;
if (ret_size_in_memory)
*ret_size_in_memory = size_in_memory;

return EFI_SUCCESS;
}

Expand Down