From d8a286d52651d44be649c502b4853c131a64829c Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Fri, 24 Nov 2023 12:26:43 +0000
Subject: WIP - ImageBase

---
 src/util/elf2efi.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/src/util/elf2efi.c b/src/util/elf2efi.c
index 31b2a2bb1..8fa86deef 100644
--- a/src/util/elf2efi.c
+++ b/src/util/elf2efi.c
@@ -728,6 +728,48 @@ static struct pe_section * process_section ( struct elf_file *elf,
 	return new;
 }
 
+/**
+ * Update image base address
+ *
+ * @v pe_header		PE file header
+ * @v pe_sections	List of PE sections
+ * @v pe_reltab		PE relocation table
+ */
+static void update_image_base ( struct pe_header *pe_header,
+				struct pe_section *pe_sections,
+				struct pe_relocs *pe_reltab ) {
+	struct pe_section *section;
+	struct pe_relocs *pe_rel;
+	unsigned long base;
+
+	/* Set ImageBase to the highest possible value, leaving space
+	 * for the PE header itself (if not deliberately overlapped).
+	 */
+	for ( section = pe_sections ; section ; section = section->next ) {
+		base = ( section->hdr.VirtualAddress -
+			 section->hdr.PointerToRawData );
+		if ( ( pe_header->nt.OptionalHeader.ImageBase == 0 ) ||
+		     ( pe_header->nt.OptionalHeader.ImageBase > base ) ) {
+			pe_header->nt.OptionalHeader.ImageBase = base;
+		}
+	}
+	base = pe_header->nt.OptionalHeader.ImageBase;
+
+	/* Adjust RVAs to match ImageBase */
+	pe_header->nt.OptionalHeader.AddressOfEntryPoint -= base;
+	pe_header->nt.OptionalHeader.BaseOfCode -= base;
+#if defined(EFI_TARGET32)
+	pe_header->nt.OptionalHeader.BaseOfData -= base;
+#endif
+	pe_header->nt.OptionalHeader.SizeOfImage -= base;
+	for ( section = pe_sections ; section ; section = section->next ) {
+		section->hdr.VirtualAddress -= base;
+	}
+	for ( pe_rel = pe_reltab ; pe_rel ; pe_rel = pe_rel->next ) {
+		pe_rel->start_rva -= base;
+	}
+}
+
 /**
  * Process relocation record
  *
@@ -1112,6 +1154,9 @@ static void elf2pe ( const char *elf_name, const char *pe_name,
 		}
 	}
 
+	/* Update image base address */
+	update_image_base ( &pe_header, pe_sections, pe_reltab );
+
 	/* Create the .reloc section */
 	*(next_pe_section) = create_reloc_section ( &pe_header, pe_reltab );
 	next_pe_section = &(*next_pe_section)->next;
-- 
cgit