x86, efi stub: Add .reloc section back into image

Some UEFI firmware will not load a .efi with a .reloc section
with a size of 0.

Therefore, we create a .efi image with 4 main areas and 3 sections.
1. PE/COFF file header
2. .setup section (covers all setup code following the first sector)
3. .reloc section (contains 1 dummy reloc entry, created in build.c)
4. .text section (covers the remaining kernel image)

To make room for the new .setup section data, the header
bugger_off_msg had to be shortened.

Reported-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Link: http://lkml.kernel.org/r/1339085121-12760-1-git-send-email-jordan.l.justen@intel.com
Tested-by: Lee G Rosenbaum <lee.g.rosenbaum@intel.com>
Tested-by: Henrik Rydberg <rydberg@euromail.se>
Cc: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/boot/header.S

@@ -94,8 +94,8 @@ bs_die:
 
 	.section ".bsdata", "a"
 bugger_off_msg:
-	.ascii	"Direct booting from floppy is no longer supported.\r\n"
+	.ascii	"Direct floppy boot is not supported. "
-	.ascii	"Please use a boot loader program instead.\r\n"
+	.ascii	"Use a boot loader program instead.\r\n"
 	.ascii	"\n"
 	.ascii	"Remove disk and press any key to reboot ...\r\n"
 	.byte	0
@@ -111,7 +111,7 @@ coff_header:
 #else
 	.word	0x8664				# x86-64
 #endif
-	.word	2				# nr_sections
+	.word	3				# nr_sections
 	.long	0 				# TimeDateStamp
 	.long	0				# PointerToSymbolTable
 	.long	1				# NumberOfSymbols
@@ -158,8 +158,8 @@ extra_header_fields:
 #else
 	.quad	0				# ImageBase
 #endif
-	.long	0x1000				# SectionAlignment
+	.long	0x20				# SectionAlignment
-	.long	0x200				# FileAlignment
+	.long	0x20				# FileAlignment
 	.word	0				# MajorOperatingSystemVersion
 	.word	0				# MinorOperatingSystemVersion
 	.word	0				# MajorImageVersion
@@ -200,8 +200,10 @@ extra_header_fields:
 
 	# Section table
 section_table:
-	.ascii	".text"
+	#
-	.byte	0
+	# The offset & size fields are filled in by build.c.
+	#
+	.ascii	".setup"
 	.byte	0
 	.byte	0
 	.long	0
@@ -217,9 +219,8 @@ section_table:
 
 	#
 	# The EFI application loader requires a relocation section
-	# because EFI applications must be relocatable. But since
+	# because EFI applications must be relocatable. The .reloc
-	# we don't need the loader to fixup any relocs for us, we
+	# offset & size fields are filled in by build.c.
-	# just create an empty (zero-length) .reloc section header.
 	#
 	.ascii	".reloc"
 	.byte	0
@@ -233,6 +234,25 @@ section_table:
 	.word	0				# NumberOfRelocations
 	.word	0				# NumberOfLineNumbers
 	.long	0x42100040			# Characteristics (section flags)
+
+	#
+	# The offset & size fields are filled in by build.c.
+	#
+	.ascii	".text"
+	.byte	0
+	.byte	0
+	.byte	0
+	.long	0
+	.long	0x0				# startup_{32,64}
+	.long	0				# Size of initialized data
+						# on disk
+	.long	0x0				# startup_{32,64}
+	.long	0				# PointerToRelocations
+	.long	0				# PointerToLineNumbers
+	.word	0				# NumberOfRelocations
+	.word	0				# NumberOfLineNumbers
+	.long	0x60500020			# Characteristics (section flags)
+
 #endif /* CONFIG_EFI_STUB */
 
 	# Kernel attributes; used by setup.  This is part 1 of the

arch/x86/boot/tools/build.c

@@ -50,6 +50,8 @@ typedef unsigned int   u32;
 u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
+#define PECOFF_RELOC_RESERVE 0x20
+
 /*----------------------------------------------------------------------*/
 
 static const u32 crctab32[] = {
@@ -133,11 +135,103 @@ static void usage(void)
 	die("Usage: build setup system [> image]");
 }
 
+#ifdef CONFIG_EFI_STUB
+
+static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
+{
+	unsigned int pe_header;
+	unsigned short num_sections;
+	u8 *section;
+
+	pe_header = get_unaligned_le32(&buf[0x3c]);
+	num_sections = get_unaligned_le16(&buf[pe_header + 6]);
+
+#ifdef CONFIG_X86_32
+	section = &buf[pe_header + 0xa8];
+#else
+	section = &buf[pe_header + 0xb8];
+#endif
+
+	while (num_sections > 0) {
+		if (strncmp((char*)section, section_name, 8) == 0) {
+			/* section header size field */
+			put_unaligned_le32(size, section + 0x8);
+
+			/* section header vma field */
+			put_unaligned_le32(offset, section + 0xc);
+
+			/* section header 'size of initialised data' field */
+			put_unaligned_le32(size, section + 0x10);
+
+			/* section header 'file offset' field */
+			put_unaligned_le32(offset, section + 0x14);
+
+			break;
+		}
+		section += 0x28;
+		num_sections--;
+	}
+}
+
+static void update_pecoff_setup_and_reloc(unsigned int size)
+{
+	u32 setup_offset = 0x200;
+	u32 reloc_offset = size - PECOFF_RELOC_RESERVE;
+	u32 setup_size = reloc_offset - setup_offset;
+
+	update_pecoff_section_header(".setup", setup_offset, setup_size);
+	update_pecoff_section_header(".reloc", reloc_offset, PECOFF_RELOC_RESERVE);
+
+	/*
+	 * Modify .reloc section contents with a single entry. The
+	 * relocation is applied to offset 10 of the relocation section.
+	 */
+	put_unaligned_le32(reloc_offset + 10, &buf[reloc_offset]);
+	put_unaligned_le32(10, &buf[reloc_offset + 4]);
+}
+
+static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
+{
+	unsigned int pe_header;
+	unsigned int text_sz = file_sz - text_start;
+
+	pe_header = get_unaligned_le32(&buf[0x3c]);
+
+	/* Size of image */
+	put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
+
+	/*
+	 * Size of code: Subtract the size of the first sector (512 bytes)
+	 * which includes the header.
+	 */
+	put_unaligned_le32(file_sz - 512, &buf[pe_header + 0x1c]);
+
+#ifdef CONFIG_X86_32
+	/*
+	 * Address of entry point.
+	 *
+	 * The EFI stub entry point is +16 bytes from the start of
+	 * the .text section.
+	 */
+	put_unaligned_le32(text_start + 16, &buf[pe_header + 0x28]);
+#else
+	/*
+	 * Address of entry point. startup_32 is at the beginning and
+	 * the 64-bit entry point (startup_64) is always 512 bytes
+	 * after. The EFI stub entry point is 16 bytes after that, as
+	 * the first instruction allows legacy loaders to jump over
+	 * the EFI stub initialisation
+	 */
+	put_unaligned_le32(text_start + 528, &buf[pe_header + 0x28]);
+#endif /* CONFIG_X86_32 */
+
+	update_pecoff_section_header(".text", text_start, text_sz);
+}
+
+#endif /* CONFIG_EFI_STUB */
+
 int main(int argc, char ** argv)
 {
-#ifdef CONFIG_EFI_STUB
-	unsigned int file_sz, pe_header;
-#endif
 	unsigned int i, sz, setup_sectors;
 	int c;
 	u32 sys_size;
@@ -163,6 +257,12 @@ int main(int argc, char ** argv)
 		die("Boot block hasn't got boot flag (0xAA55)");
 	fclose(file);
 
+#ifdef CONFIG_EFI_STUB
+	/* Reserve 0x20 bytes for .reloc section */
+	memset(buf+c, 0, PECOFF_RELOC_RESERVE);
+	c += PECOFF_RELOC_RESERVE;
+#endif
+
 	/* Pad unused space with zeros */
 	setup_sectors = (c + 511) / 512;
 	if (setup_sectors < SETUP_SECT_MIN)
@@ -170,6 +270,10 @@ int main(int argc, char ** argv)
 	i = setup_sectors*512;
 	memset(buf+c, 0, i-c);
 
+#ifdef CONFIG_EFI_STUB
+	update_pecoff_setup_and_reloc(i);
+#endif
+
 	/* Set the default root device */
 	put_unaligned_le16(DEFAULT_ROOT_DEV, &buf[508]);
 
@@ -194,66 +298,8 @@ int main(int argc, char ** argv)
 	put_unaligned_le32(sys_size, &buf[0x1f4]);
 
 #ifdef CONFIG_EFI_STUB
-	file_sz = sz + i + ((sys_size * 16) - sz);
+	update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
-
+#endif
-	pe_header = get_unaligned_le32(&buf[0x3c]);
-
-	/* Size of image */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
-
-	/*
-	 * Subtract the size of the first section (512 bytes) which
-	 * includes the header and .reloc section. The remaining size
-	 * is that of the .text section.
-	 */
-	file_sz -= 512;
-
-	/* Size of code */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0x1c]);
-
-#ifdef CONFIG_X86_32
-	/*
-	 * Address of entry point.
-	 *
-	 * The EFI stub entry point is +16 bytes from the start of
-	 * the .text section.
-	 */
-	put_unaligned_le32(i + 16, &buf[pe_header + 0x28]);
-
-	/* .text size */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0xb0]);
-
-	/* .text vma */
-	put_unaligned_le32(0x200, &buf[pe_header + 0xb4]);
-
-	/* .text size of initialised data */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0xb8]);
-
-	/* .text file offset */
-	put_unaligned_le32(0x200, &buf[pe_header + 0xbc]);
-#else
-	/*
-	 * Address of entry point. startup_32 is at the beginning and
-	 * the 64-bit entry point (startup_64) is always 512 bytes
-	 * after. The EFI stub entry point is 16 bytes after that, as
-	 * the first instruction allows legacy loaders to jump over
-	 * the EFI stub initialisation
-	 */
-	put_unaligned_le32(i + 528, &buf[pe_header + 0x28]);
-
-	/* .text size */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0xc0]);
-
-	/* .text vma */
-	put_unaligned_le32(0x200, &buf[pe_header + 0xc4]);
-
-	/* .text size of initialised data */
-	put_unaligned_le32(file_sz, &buf[pe_header + 0xc8]);
-
-	/* .text file offset */
-	put_unaligned_le32(0x200, &buf[pe_header + 0xcc]);
-#endif /* CONFIG_X86_32 */
-#endif /* CONFIG_EFI_STUB */
 
 	crc = partial_crc32(buf, i, crc);
 	if (fwrite(buf, 1, i, stdout) != i)