1 files changed, 74 insertions, 0 deletions
diff --git a/src/boot/efi/linux.c b/src/boot/efi/linux.c
new file mode 100644
index 0000000..4d44671
--- /dev/null
+++ b/src/boot/efi/linux.c
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <efi.h>
+#include <efilib.h>
+
+#include "linux.h"
+#include "util.h"
+
+#ifdef __i386__
+#define __regparm0__ __attribute__((regparm(0)))
+#else
+#define __regparm0__
+#endif
+
+typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct boot_params *params) __regparm0__;
+static VOID linux_efi_handover(EFI_HANDLE image, struct boot_params *params) {
+        handover_f handover;
+        UINTN start = (UINTN)params->hdr.code32_start;
+
+#ifdef __x86_64__
+        asm volatile ("cli");
+        start += 512;
+#endif
+        handover = (handover_f)(start + params->hdr.handover_offset);
+        handover(image, ST, params);
+}
+
+EFI_STATUS linux_exec(EFI_HANDLE *image,
+                      CHAR8 *cmdline, UINTN cmdline_len,
+                      UINTN linux_addr,
+                      UINTN initrd_addr, UINTN initrd_size) {
+        struct boot_params *image_params;
+        struct boot_params *boot_params;
+        UINT8 setup_sectors;
+        EFI_PHYSICAL_ADDRESS addr;
+        EFI_STATUS err;
+
+        image_params = (struct boot_params *) linux_addr;
+
+        if (image_params->hdr.boot_flag != 0xAA55 ||
+            image_params->hdr.header != SETUP_MAGIC ||
+            image_params->hdr.version < 0x20b ||
+            !image_params->hdr.relocatable_kernel)
+                return EFI_LOAD_ERROR;
+
+        boot_params = (struct boot_params *) 0xFFFFFFFF;
+        err = uefi_call_wrapper(BS->AllocatePages, 4, AllocateMaxAddress, EfiLoaderData,
+                                EFI_SIZE_TO_PAGES(0x4000), (EFI_PHYSICAL_ADDRESS*) &boot_params);
+        if (EFI_ERROR(err))
+                return err;
+
+        ZeroMem(boot_params, 0x4000);
+        CopyMem(&boot_params->hdr, &image_params->hdr, sizeof(struct setup_header));
+        boot_params->hdr.type_of_loader = 0xff;
+        setup_sectors = image_params->hdr.setup_sects > 0 ? image_params->hdr.setup_sects : 4;
+        boot_params->hdr.code32_start = (UINT32)linux_addr + (setup_sectors + 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_params->hdr.cmd_line_ptr = (UINT32)addr;
+        }
+
+        boot_params->hdr.ramdisk_image = (UINT32)initrd_addr;
+        boot_params->hdr.ramdisk_size = (UINT32)initrd_size;
+
+        linux_efi_handover(image, boot_params);
+        return EFI_LOAD_ERROR;
+}