From 6c06378c1bf6ae21788427e62ab0011b7f1bc2f0 Mon Sep 17 00:00:00 2001
From: Michael Chang <mchang@suse.com>
Date: Fri, 25 Nov 2022 16:11:24 +0800
Subject: [PATCH] xen_boot: add missing grub_arch_efi_linux_load_image_header

The new xen_boot module has used grub_arch_efi_linux_load_image_header
exported by grub-core/loader/arm64/linux.c. It is not a problem for
upstream but many downstream projects may not use it and take
grub-core/loader/arm64/efi/linux.c as a replacement as PE entry is the
preferred way in combination with shim loader.

This patch did a trivial workaround just adding back the dropped
defintion to the xen_boot itself.

Signed-off-by: Michael Chang <mchang@suse.com>
---
 grub-core/loader/arm64/xen_boot.c | 50 +++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/grub-core/loader/arm64/xen_boot.c b/grub-core/loader/arm64/xen_boot.c
index 26e1472c9..b82a2db89 100644
--- a/grub-core/loader/arm64/xen_boot.c
+++ b/grub-core/loader/arm64/xen_boot.c
@@ -84,6 +84,56 @@ static int loaded;
 static struct xen_boot_binary *xen_hypervisor;
 static struct xen_boot_binary *module_head;
 
+/* The function is exported by grub-core/loader/arm64/linux.c that is not built
+ * because we use PE entry provided by grub-core/loader/arm64/efi/linux.c
+ */
+static bool initrd_use_loadfile2 = false;
+
+grub_err_t
+grub_arch_efi_linux_load_image_header (grub_file_t file,
+                                      struct linux_arch_kernel_header * lh)
+{
+  grub_file_seek (file, 0);
+  if (grub_file_read (file, lh, sizeof (*lh)) < (grub_ssize_t) sizeof (*lh))
+    return grub_error(GRUB_ERR_FILE_READ_ERROR, "failed to read Linux image header");
+
+  if ((lh->code0 & 0xffff) != GRUB_PE32_MAGIC)
+    return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
+		       N_("plain image kernel not supported - rebuild with CONFIG_(U)EFI_STUB enabled"));
+
+  grub_dprintf ("linux", "UEFI stub kernel:\n");
+  grub_dprintf ("linux", "PE/COFF header @ %08x\n", lh->hdr_offset);
+
+  /*
+   * The PE/COFF spec permits the COFF header to appear anywhere in the file, so
+   * we need to double check whether it was where we expected it, and if not, we
+   * must load it from the correct offset into the pe_image_header field of
+   * struct linux_arch_kernel_header.
+   */
+  if ((grub_uint8_t *) lh + lh->hdr_offset != (grub_uint8_t *) &lh->pe_image_header)
+    {
+      if (grub_file_seek (file, lh->hdr_offset) == (grub_off_t) -1
+          || grub_file_read (file, &lh->pe_image_header,
+                             sizeof (struct grub_pe_image_header))
+             != sizeof (struct grub_pe_image_header))
+        return grub_error (GRUB_ERR_FILE_READ_ERROR, "failed to read COFF image header");
+    }
+
+  /*
+   * Linux kernels built for any architecture are guaranteed to support the
+   * LoadFile2 based initrd loading protocol if the image version is >= 1.
+   */
+  if (lh->pe_image_header.optional_header.major_image_version >= 1)
+    initrd_use_loadfile2 = true;
+  else
+    initrd_use_loadfile2 = false;
+
+  grub_dprintf ("linux", "LoadFile2 initrd loading %sabled\n",
+                initrd_use_loadfile2 ? "en" : "dis");
+
+  return GRUB_ERR_NONE;
+}
+
 static __inline grub_addr_t
 xen_boot_address_align (grub_addr_t start, grub_size_t align)
 {
-- 
2.41.0