linux_dsm_epyc7002/arch/x86/boot/tools/build.c
David Woodhouse 99f857db88 x86, build: Dynamically find entry points in compressed startup code
We have historically hard-coded entry points in head.S just so it's easy
to build the executable/bzImage headers with references to them.

Unfortunately, this leads to boot loaders abusing these "known" addresses
even when they are *explicitly* told that they "should look at the ELF
header to find this address, as it may change in the future". And even
when the address in question *has* actually been changed in the past,
without fanfare or thought to compatibility.

Thus we have bootloaders doing stunningly broken things like jumping
to offset 0x200 in the kernel startup code in 64-bit mode, *hoping*
that startup_64 is still there (it has moved at least once
before). And hoping that it's actually a 64-bit kernel despite the
fact that we don't give them any indication of that fact.

This patch should hopefully remove the temptation to abuse internal
addresses in future, where sternly worded comments have not sufficed.
Instead of having hard-coded addresses and saying "please don't abuse
these", we actually pull the addresses out of the ELF payload into
zoffset.h, and make build.c shove them back into the right places in
the bzImage header.

Rather than including zoffset.h into build.c and thus having to rebuild
the tool for every kernel build, we parse it instead. The parsing code
is small and simple.

This patch doesn't actually move any of the interesting entry points, so
any offending bootloader will still continue to "work" after this patch
is applied. For some version of "work" which includes jumping into the
compressed payload and crashing, if the bzImage it's given is a 32-bit
kernel. No change there then.

[ hpa: some of the issues in the description are addressed or
  retconned by the 2.12 boot protocol.  This patch has been edited to
  only remove fixed addresses that were *not* thus retconned. ]

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Link: http://lkml.kernel.org/r/1358513837.2397.247.camel@shinybook.infradead.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Fleming <matt.fleming@intel.com>
2013-01-27 20:19:37 -08:00

376 lines
11 KiB
C

/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1997 Martin Mares
* Copyright (C) 2007 H. Peter Anvin
*/
/*
* This file builds a disk-image from two different files:
*
* - setup: 8086 machine code, sets up system parm
* - system: 80386 code for actual system
*
* It does some checking that all files are of the correct type, and
* just writes the result to stdout, removing headers and padding to
* the right amount. It also writes some system data to stderr.
*/
/*
* Changes by tytso to allow root device specification
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
* Cross compiling fixes by Gertjan van Wingerde, July 1996
* Rewritten by Martin Mares, April 1997
* Substantially overhauled by H. Peter Anvin, April 2007
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <tools/le_byteshift.h>
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
#define DEFAULT_MAJOR_ROOT 0
#define DEFAULT_MINOR_ROOT 0
#define DEFAULT_ROOT_DEV (DEFAULT_MAJOR_ROOT << 8 | DEFAULT_MINOR_ROOT)
/* Minimal number of setup sectors */
#define SETUP_SECT_MIN 5
#define SETUP_SECT_MAX 64
/* This must be large enough to hold the entire setup */
u8 buf[SETUP_SECT_MAX*512];
int is_big_kernel;
#define PECOFF_RELOC_RESERVE 0x20
unsigned long efi_stub_entry;
unsigned long efi_pe_entry;
unsigned long startup_64;
/*----------------------------------------------------------------------*/
static const u32 crctab32[] = {
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
0x2d02ef8d
};
static u32 partial_crc32_one(u8 c, u32 crc)
{
return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
}
static u32 partial_crc32(const u8 *s, int len, u32 crc)
{
while (len--)
crc = partial_crc32_one(*s++, crc);
return crc;
}
static void die(const char * str, ...)
{
va_list args;
va_start(args, str);
vfprintf(stderr, str, args);
fputc('\n', stderr);
exit(1);
}
static void usage(void)
{
die("Usage: build setup system [zoffset.h] [> 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]);
/*
* Address of entry point for PE/COFF executable
*/
put_unaligned_le32(text_start + efi_pe_entry, &buf[pe_header + 0x28]);
update_pecoff_section_header(".text", text_start, text_sz);
}
#endif /* CONFIG_EFI_STUB */
/*
* Parse zoffset.h and find the entry points. We could just #include zoffset.h
* but that would mean tools/build would have to be rebuilt every time. It's
* not as if parsing it is hard...
*/
#define PARSE_ZOFS(p, sym) do { \
if (!strncmp(p, "#define ZO_" #sym " ", 11+sizeof(#sym))) \
sym = strtoul(p + 11 + sizeof(#sym), NULL, 16); \
} while (0)
static void parse_zoffset(char *fname)
{
FILE *file;
char *p;
int c;
file = fopen(fname, "r");
if (!file)
die("Unable to open `%s': %m", fname);
c = fread(buf, 1, sizeof(buf) - 1, file);
if (ferror(file))
die("read-error on `zoffset.h'");
buf[c] = 0;
p = (char *)buf;
while (p && *p) {
PARSE_ZOFS(p, efi_stub_entry);
PARSE_ZOFS(p, efi_pe_entry);
PARSE_ZOFS(p, startup_64);
p = strchr(p, '\n');
while (p && (*p == '\r' || *p == '\n'))
p++;
}
}
int main(int argc, char ** argv)
{
unsigned int i, sz, setup_sectors;
int c;
u32 sys_size;
struct stat sb;
FILE *file;
int fd;
void *kernel;
u32 crc = 0xffffffffUL;
/* Defaults for old kernel */
#ifdef CONFIG_X86_32
efi_pe_entry = 0x10;
efi_stub_entry = 0x30;
#else
efi_pe_entry = 0x210;
efi_stub_entry = 0x230;
startup_64 = 0x200;
#endif
if (argc == 4)
parse_zoffset(argv[3]);
else if (argc != 3)
usage();
/* Copy the setup code */
file = fopen(argv[1], "r");
if (!file)
die("Unable to open `%s': %m", argv[1]);
c = fread(buf, 1, sizeof(buf), file);
if (ferror(file))
die("read-error on `setup'");
if (c < 1024)
die("The setup must be at least 1024 bytes");
if (get_unaligned_le16(&buf[510]) != 0xAA55)
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]);
fprintf(stderr, "Setup is %d bytes (padded to %d bytes).\n", c, i);
/* Open and stat the kernel file */
fd = open(argv[2], O_RDONLY);
if (fd < 0)
die("Unable to open `%s': %m", argv[2]);
if (fstat(fd, &sb))
die("Unable to stat `%s': %m", argv[2]);
sz = sb.st_size;
fprintf (stderr, "System is %d kB\n", (sz+1023)/1024);
kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
if (kernel == MAP_FAILED)
die("Unable to mmap '%s': %m", argv[2]);
/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
sys_size = (sz + 15 + 4) / 16;
/* Patch the setup code with the appropriate size parameters */
buf[0x1f1] = setup_sectors-1;
put_unaligned_le32(sys_size, &buf[0x1f4]);
#ifdef CONFIG_EFI_STUB
update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
#ifdef CONFIG_X86_64 /* Yes, this is really how we defined it :( */
efi_stub_entry -= 0x200;
#endif
put_unaligned_le32(efi_stub_entry, &buf[0x264]);
#endif
crc = partial_crc32(buf, i, crc);
if (fwrite(buf, 1, i, stdout) != i)
die("Writing setup failed");
/* Copy the kernel code */
crc = partial_crc32(kernel, sz, crc);
if (fwrite(kernel, 1, sz, stdout) != sz)
die("Writing kernel failed");
/* Add padding leaving 4 bytes for the checksum */
while (sz++ < (sys_size*16) - 4) {
crc = partial_crc32_one('\0', crc);
if (fwrite("\0", 1, 1, stdout) != 1)
die("Writing padding failed");
}
/* Write the CRC */
fprintf(stderr, "CRC %x\n", crc);
put_unaligned_le32(crc, buf);
if (fwrite(buf, 1, 4, stdout) != 4)
die("Writing CRC failed");
close(fd);
/* Everything is OK */
return 0;
}