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x86, efi stub: Add .reloc section back into image
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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>
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Jordan Justen authored and H. Peter Anvin committed Jun 7, 2012
1 parent f6175f5 commit 743628e
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Showing 2 changed files with 140 additions and 74 deletions.
42 changes: 31 additions & 11 deletions arch/x86/boot/header.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -94,10 +94,10 @@ bs_die:

.section ".bsdata", "a"
bugger_off_msg:
.ascii "Direct booting from floppy is no longer supported.\r\n"
.ascii "Please use a boot loader program instead.\r\n"
.ascii "Direct floppy boot is not supported. "
.ascii "Use a boot loader program instead.\r\n"
.ascii "\n"
.ascii "Remove disk and press any key to reboot . . .\r\n"
.ascii "Remove disk and press any key to reboot ...\r\n"
.byte 0

#ifdef CONFIG_EFI_STUB
Expand All @@ -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
Expand Down Expand Up @@ -158,8 +158,8 @@ extra_header_fields:
#else
.quad 0 # ImageBase
#endif
.long 0x1000 # SectionAlignment
.long 0x200 # FileAlignment
.long 0x20 # SectionAlignment
.long 0x20 # FileAlignment
.word 0 # MajorOperatingSystemVersion
.word 0 # MinorOperatingSystemVersion
.word 0 # MajorImageVersion
Expand Down Expand Up @@ -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
Expand All @@ -217,9 +219,8 @@ section_table:

#
# The EFI application loader requires a relocation section
# because EFI applications must be relocatable. But since
# we don't need the loader to fixup any relocs for us, we
# just create an empty (zero-length) .reloc section header.
# because EFI applications must be relocatable. The .reloc
# offset & size fields are filled in by build.c.
#
.ascii ".reloc"
.byte 0
Expand All @@ -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
Expand Down
172 changes: 109 additions & 63 deletions arch/x86/boot/tools/build.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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[] = {
Expand Down Expand Up @@ -133,11 +135,103 @@ static void usage(void)
die("Usage: build setup system [> image]");
}

int main(int argc, char ** argv)
{
#ifdef CONFIG_EFI_STUB
unsigned int file_sz, pe_header;

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)
{
unsigned int i, sz, setup_sectors;
int c;
u32 sys_size;
Expand All @@ -163,13 +257,23 @@ 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)
setup_sectors = SETUP_SECT_MIN;
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]);

Expand All @@ -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);

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 */
update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
#endif

crc = partial_crc32(buf, i, crc);
if (fwrite(buf, 1, i, stdout) != i)
Expand Down

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