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-rw-r--r--src/boot/efi/linux.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/src/boot/efi/linux.c b/src/boot/efi/linux.c
new file mode 100644
index 0000000..5b4c085
--- /dev/null
+++ b/src/boot/efi/linux.c
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <efi.h>
+#include <efilib.h>
+
+#include "linux.h"
+#include "util.h"
+
+#define SETUP_MAGIC 0x53726448 /* "HdrS" */
+struct SetupHeader {
+ UINT8 boot_sector[0x01f1];
+ UINT8 setup_secs;
+ UINT16 root_flags;
+ UINT32 sys_size;
+ UINT16 ram_size;
+ UINT16 video_mode;
+ UINT16 root_dev;
+ UINT16 signature;
+ UINT16 jump;
+ UINT32 header;
+ UINT16 version;
+ UINT16 su_switch;
+ UINT16 setup_seg;
+ UINT16 start_sys;
+ UINT16 kernel_ver;
+ UINT8 loader_id;
+ UINT8 load_flags;
+ UINT16 movesize;
+ UINT32 code32_start;
+ UINT32 ramdisk_start;
+ UINT32 ramdisk_len;
+ UINT32 bootsect_kludge;
+ UINT16 heap_end;
+ UINT8 ext_loader_ver;
+ UINT8 ext_loader_type;
+ UINT32 cmd_line_ptr;
+ UINT32 ramdisk_max;
+ UINT32 kernel_alignment;
+ UINT8 relocatable_kernel;
+ UINT8 min_alignment;
+ UINT16 xloadflags;
+ UINT32 cmdline_size;
+ UINT32 hardware_subarch;
+ UINT64 hardware_subarch_data;
+ UINT32 payload_offset;
+ UINT32 payload_length;
+ UINT64 setup_data;
+ UINT64 pref_address;
+ UINT32 init_size;
+ UINT32 handover_offset;
+} __attribute__((packed));
+
+#ifdef __x86_64__
+typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct SetupHeader *setup);
+static VOID linux_efi_handover(EFI_HANDLE image, struct SetupHeader *setup) {
+ handover_f handover;
+
+ asm volatile ("cli");
+ handover = (handover_f)((UINTN)setup->code32_start + 512 + setup->handover_offset);
+ handover(image, ST, setup);
+}
+#else
+typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct SetupHeader *setup) __attribute__((regparm(0)));
+static VOID linux_efi_handover(EFI_HANDLE image, struct SetupHeader *setup) {
+ handover_f handover;
+
+ handover = (handover_f)((UINTN)setup->code32_start + setup->handover_offset);
+ handover(image, ST, setup);
+}
+#endif
+
+EFI_STATUS linux_exec(EFI_HANDLE *image,
+ CHAR8 *cmdline, UINTN cmdline_len,
+ UINTN linux_addr,
+ UINTN initrd_addr, UINTN initrd_size, BOOLEAN secure) {
+ struct SetupHeader *image_setup;
+ struct SetupHeader *boot_setup;
+ EFI_PHYSICAL_ADDRESS addr;
+ EFI_STATUS err;
+
+ image_setup = (struct SetupHeader *)(linux_addr);
+ if (image_setup->signature != 0xAA55 || image_setup->header != SETUP_MAGIC)
+ return EFI_LOAD_ERROR;
+
+ if (image_setup->version < 0x20b || !image_setup->relocatable_kernel)
+ return EFI_LOAD_ERROR;
+
+ addr = 0x3fffffff;
+ err = uefi_call_wrapper(BS->AllocatePages, 4, AllocateMaxAddress, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(0x4000), &addr);
+ if (EFI_ERROR(err))
+ return err;
+ boot_setup = (struct SetupHeader *)(UINTN)addr;
+ ZeroMem(boot_setup, 0x4000);
+ CopyMem(boot_setup, image_setup, sizeof(struct SetupHeader));
+ boot_setup->loader_id = 0xff;
+
+ if (secure) {
+ /* set secure boot flag in linux kernel zero page, see
+ - Documentation/x86/zero-page.txt
+ - arch/x86/include/uapi/asm/bootparam.h
+ - drivers/firmware/efi/libstub/secureboot.c
+ in the linux kernel source tree
+ Possible values: 0 (unassigned), 1 (undetected), 2 (disabled), 3 (enabled)
+ */
+ boot_setup->boot_sector[0x1ec] = 3;
+ }
+
+ boot_setup->code32_start = (UINT32)linux_addr + (image_setup->setup_secs+1) * 512;
+
+ if (cmdline) {
+ addr = 0xA0000;
+ err = uefi_call_wrapper(BS->AllocatePages, 4, AllocateMaxAddress, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(cmdline_len + 1), &addr);
+ if (EFI_ERROR(err))
+ return err;
+ CopyMem((VOID *)(UINTN)addr, cmdline, cmdline_len);
+ ((CHAR8 *)(UINTN)addr)[cmdline_len] = 0;
+ boot_setup->cmd_line_ptr = (UINT32)addr;
+ }
+
+ boot_setup->ramdisk_start = (UINT32)initrd_addr;
+ boot_setup->ramdisk_len = (UINT32)initrd_size;
+
+ linux_efi_handover(image, boot_setup);
+ return EFI_LOAD_ERROR;
+}