Commit fa575052 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar
Browse files

x86/boot: Drop PE/COFF .reloc section 



Ancient buggy EFI loaders may have required a .reloc section to be
present at some point in time, but this has not been true for a long
time so the .reloc section can just be dropped.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-16-ardb@google.com
parent efa089e6

arch/x86/boot/header.S

+0 −20
Original line number Diff line number Diff line
@@ -155,26 +155,6 @@ section_table: 
		IMAGE_SCN_MEM_READ		| \

		IMAGE_SCN_MEM_EXECUTE		# Characteristics



	#

	# The EFI application loader requires a relocation section

	# because EFI applications must be relocatable. The .reloc

	# offset & size fields are filled in by build.c.

	#

	.ascii	".reloc"

	.byte	0

	.byte	0

	.long	0

	.long	0

	.long	0				# SizeOfRawData

	.long	0				# PointerToRawData

	.long	0				# PointerToRelocations

	.long	0				# PointerToLineNumbers

	.word	0				# NumberOfRelocations

	.word	0				# NumberOfLineNumbers

	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \

		IMAGE_SCN_MEM_READ		| \

		IMAGE_SCN_MEM_DISCARDABLE	# Characteristics



#ifdef CONFIG_EFI_MIXED

	#

	# The offset & size fields are filled in by build.c.

arch/x86/boot/setup.ld

+2 −2
Original line number Diff line number Diff line
@@ -40,8 +40,8 @@ SECTIONS 
		setup_sig = .;

		LONG(0x5a5aaa55)



		/* Reserve some extra space for the reloc and compat sections */

		setup_size = ALIGN(ABSOLUTE(.) + 64, 512);

		/* Reserve some extra space for the compat section */

		setup_size = ALIGN(ABSOLUTE(.) + 32, 512);

		setup_sects = ABSOLUTE(setup_size / 512);

	}

arch/x86/boot/tools/build.c

+5 −29
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ typedef unsigned int u32; 
/* This must be large enough to hold the entire setup */

u8 buf[SETUP_SECT_MAX*512];



#define PECOFF_RELOC_RESERVE 0x20

#define PECOFF_COMPAT_RESERVE 0x20



static unsigned long efi32_pe_entry;
@@ -180,24 +179,13 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz 
	update_pecoff_section_header_fields(section_name, offset, size, size, offset);

}



static void update_pecoff_setup_and_reloc(unsigned int size)

static void update_pecoff_setup(unsigned int size)

{

	u32 setup_offset = 0x200;

	u32 reloc_offset = size - PECOFF_RELOC_RESERVE - PECOFF_COMPAT_RESERVE;

#ifdef CONFIG_EFI_MIXED

	u32 compat_offset = reloc_offset + PECOFF_RELOC_RESERVE;

#endif

	u32 setup_size = reloc_offset - setup_offset;

	u32 compat_offset = size - PECOFF_COMPAT_RESERVE;

	u32 setup_size = compat_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]);



#ifdef CONFIG_EFI_MIXED

	update_pecoff_section_header(".compat", compat_offset, PECOFF_COMPAT_RESERVE);
@@ -214,21 +202,10 @@ static void update_pecoff_setup_and_reloc(unsigned int size) 
#endif

}



static int reserve_pecoff_reloc_section(int c)

{

	/* Reserve 0x20 bytes for .reloc section */

	memset(buf+c, 0, PECOFF_RELOC_RESERVE);

	return PECOFF_RELOC_RESERVE;

}



#else



static inline void update_pecoff_setup_and_reloc(unsigned int size) {}

static inline void update_pecoff_setup(unsigned int size) {}



static inline int reserve_pecoff_reloc_section(int c)

{

	return 0;

}

#endif /* CONFIG_EFI_STUB */



static int reserve_pecoff_compat_section(int c)
@@ -307,7 +284,6 @@ int main(int argc, char ** argv) 
	fclose(file);



	c += reserve_pecoff_compat_section(c);

	c += reserve_pecoff_reloc_section(c);



	/* Pad unused space with zeros */

	setup_sectors = (c + 511) / 512;
@@ -316,7 +292,7 @@ int main(int argc, char ** argv) 
	i = setup_sectors*512;

	memset(buf+c, 0, i-c);



	update_pecoff_setup_and_reloc(i);

	update_pecoff_setup(i);



	/* Open and stat the kernel file */

	fd = open(argv[2], O_RDONLY);