#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <elf.h>
#include <byteswap.h>
#define USE_BSD
#include <endian.h>
#include <regex.h>
#include <tools/le_byteshift.h>
static void die(char *fmt, ...);
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
static Elf32_Ehdr ehdr;
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;
static unsigned long reloc16_count, reloc16_idx;
static unsigned long *relocs16;
struct section {
Elf32_Shdr shdr;
struct section *link;
Elf32_Sym *symtab;
Elf32_Rel *reltab;
char *strtab;
};
static struct section *secs;
enum symtype {
S_ABS,
S_REL,
S_SEG,
S_LIN,
S_NSYMTYPES
};
static const char * const sym_regex_kernel[S_NSYMTYPES] = {
/*
* Following symbols have been audited. There values are constant and do
* not change if bzImage is loaded at a different physical address than
* the address for which it has been compiled. Don't warn user about
* absolute relocations present w.r.t these symbols.
*/
[S_ABS] =
"^(xen_irq_disable_direct_reloc$|"
"xen_save_fl_direct_reloc$|"
"VDSO|"
"__crc_)",
/*
* These symbols are known to be relative, even if the linker marks them
* as absolute (typically defined outside any section in the linker script.)
*/
[S_REL] =
"^(__init_(begin|end)|"
"__x86_cpu_dev_(start|end)|"
"(__parainstructions|__alt_instructions)(|_end)|"
"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
"__(start|end)_pci_.*|"
"__(start|end)_builtin_fw|"
"__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
"__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
"__(start|stop)___param|"
"__(start|stop)___modver|"
"__(start|stop)___bug_table|"
"__tracedata_(start|end)|"
"__(start|stop)_notes|"
"__end_rodata|"
"__initramfs_start|"
"(jiffies|jiffies_64)|"
"_end)$"
};
static const char * const sym_regex_realmode[S_NSYMTYPES] = {
/*
* These symbols are known to be relative, even if the linker marks them
* as absolute (typically defined outside any section in the linker script.)
*/
[S_REL] =
"^pa_",
/*
* These are 16-bit segment symbols when compiling 16-bit code.
*/
[S_SEG] =
"^real_mode_seg$",
/*
* These are offsets belonging to segments, as opposed to linear addresses,
* when compiling 16-bit code.
*/
[S_LIN] =
"^pa_",
};
static const char * const *sym_regex;
static regex_t sym_regex_c[S_NSYMTYPES];
static int is_reloc(enum symtype type, const char *sym_name)
{
return sym_regex[type] &&
!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
}
static void regex_init(int use_real_mode)
{
char errbuf[128];
int err;
int i;
if (use_real_mode)
sym_regex = sym_regex_realmode;
else
sym_regex = sym_regex_kernel;
for (i = 0; i < S_NSYMTYPES; i++) {
if (!sym_regex[i])
continue;
err = regcomp(&sym_regex_c[i], sym_regex[i],
REG_EXTENDED|REG_NOSUB);
if (err) {
regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
die("%s", errbuf);
}
}
}
static void die(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(1);
}
static const char *sym_type(unsigned type)
{
static const char *type_name[] = {
#define SYM_TYPE(X) [X] = #X
SYM_TYPE(STT_NOTYPE),
SYM_TYPE(STT_OBJECT),
SYM_TYPE(STT_FUNC),
SYM_TYPE(STT_SECTION),
SYM_TYPE(STT_FILE),
SYM_TYPE(STT_COMMON),
SYM_TYPE(STT_TLS),
#undef SYM_TYPE
};
const char *name = "unknown sym type name";
if (type < ARRAY_SIZE(type_name)) {
name = type_name[type];
}
return name;
}
static const char *sym_bind(unsigned bind)
{
static const char *bind_name[] = {
#define SYM_BIND(X) [X] = #X
SYM_BIND(STB_LOCAL),
SYM_BIND(STB_GLOBAL),
SYM_BIND(STB_WEAK),
#undef SYM_BIND
};
const char *name = "unknown sym bind name";
if (bind < ARRAY_SIZE(bind_name)) {
name = bind_name[bind];
}
return name;
}
static const char *sym_visibility(unsigned visibility)
{
static const char *visibility_name[] = {
#define SYM_VISIBILITY(X) [X] = #X
SYM_VISIBILITY(STV_DEFAULT),
SYM_VISIBILITY(STV_INTERNAL),
SYM_VISIBILITY(STV_HIDDEN),
SYM_VISIBILITY(STV_PROTECTED),
#undef SYM_VISIBILITY
};
const char *name = "unknown sym visibility name";
if (visibility < ARRAY_SIZE(visibility_name)) {
name = visibility_name[visibility];
}
return name;
}
static const char *rel_type(unsigned type)
{
static const char *type_name[] = {
#define REL_TYPE(X) [X] = #X
REL_TYPE(R_386_NONE),
REL_TYPE(R_386_32),
REL_TYPE(R_386_PC32),
REL_TYPE(R_386_GOT32),
REL_TYPE(R_386_PLT32),
REL_TYPE(R_386_COPY),
REL_TYPE(R_386_GLOB_DAT),
REL_TYPE(R_386_JMP_SLOT),
REL_TYPE(R_386_RELATIVE),
REL_TYPE(R_386_GOTOFF),
REL_TYPE(R_386_GOTPC),
REL_TYPE(R_386_8),
REL_TYPE(R_386_PC8),
REL_TYPE(R_386_16),
REL_TYPE(R_386_PC16),
#undef REL_TYPE
};
const char *name = "unknown type rel type name";
if (type < ARRAY_SIZE(type_name) && type_name[type]) {
name = type_name[type];
}
return name;
}
static const char *sec_name(unsigned shndx)
{
const char *sec_strtab;
const char *name;
sec_strtab = secs[ehdr.e_shstrndx].strtab;
name = "<noname>";
if (shndx < ehdr.e_shnum) {
name = sec_strtab + secs[shndx].shdr.sh_name;
}
else if (shndx == SHN_ABS) {
name = "ABSOLUTE";
}
else if (shndx == SHN_COMMON) {
name = "COMMON";
}
return name;
}
static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
{
const char *name;
name = "<noname>";
if (sym->st_name) {
name = sym_strtab + sym->st_name;
}
else {
name = sec_name(sym->st_shndx);
}
return name;
}
#if BYTE_ORDER == LITTLE_ENDIAN
#define le16_to_cpu(val) (val)
#define le32_to_cpu(val) (val)
#endif
#if BYTE_ORDER == BIG_ENDIAN
#define le16_to_cpu(val) bswap_16(val)
#define le32_to_cpu(val) bswap_32(val)
#endif
static uint16_t elf16_to_cpu(uint16_t val)
{
return le16_to_cpu(val);
}
static uint32_t elf32_to_cpu(uint32_t val)
{
return le32_to_cpu(val);
}
static void read_ehdr(FILE *fp)
{
if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
die("Cannot read ELF header: %s\n",
strerror(errno));
}
if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
die("No ELF magic\n");
}
if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
die("Not a 32 bit executable\n");
}
if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
die("Not a LSB ELF executable\n");
}
if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
die("Unknown ELF version\n");
}
/* Convert the fields to native endian */
ehdr.e_type = elf16_to_cpu(ehdr.e_type);
ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
ehdr.e_version = elf32_to_cpu(ehdr.e_version);
ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
die("Unsupported ELF header type\n");
}
if (ehdr.e_machine != EM_386) {
die("Not for x86\n");
}
if (ehdr.e_version != EV_CURRENT) {
die("Unknown ELF version\n");
}
if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
die("Bad Elf header size\n");
}
if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
die("Bad program header entry\n");
}
if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
die("Bad section header entry\n");
}
if (ehdr.e_shstrndx >= ehdr.e_shnum) {
die("String table index out of bounds\n");
}
}
static void read_shdrs(FILE *fp)
{
int i;
Elf32_Shdr shdr;
secs = calloc(ehdr.e_shnum, sizeof(struct section));
if (!secs) {
die("Unable to allocate %d section headers\n",
ehdr.e_shnum);
}
if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
ehdr.e_shoff, strerror(errno));
}
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (fread(&shdr, sizeof shdr, 1, fp) != 1)
die("Cannot read ELF section headers %d/%d: %s\n",
i, ehdr.e_shnum, strerror(errno));
sec->shdr.sh_name = elf32_to_cpu(shdr.sh_name);
sec->shdr.sh_type = elf32_to_cpu(shdr.sh_type);
sec->shdr.sh_flags = elf32_to_cpu(shdr.sh_flags);
sec->shdr.sh_addr = elf32_to_cpu(shdr.sh_addr);
sec->shdr.sh_offset = elf32_to_cpu(shdr.sh_offset);
sec->shdr.sh_size = elf32_to_cpu(shdr.sh_size);
sec->shdr.sh_link = elf32_to_cpu(shdr.sh_link);
sec->shdr.sh_info = elf32_to_cpu(shdr.sh_info);
sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
sec->shdr.sh_entsize = elf32_to_cpu(shdr.sh_entsize);
if (sec->shdr.sh_link < ehdr.e_shnum)
sec->link = &secs[sec->shdr.sh_link];
}
}
static void read_strtabs(FILE *fp)
{
int i;
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_STRTAB) {
continue;
}
sec->strtab = malloc(sec->shdr.sh_size);
if (!sec->strtab) {
die("malloc of %d bytes for strtab failed\n",
sec->shdr.sh_size);
}
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
sec->shdr.sh_offset, strerror(errno));
}
if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
!= sec->shdr.sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
}
}
static void read_symtabs(FILE *fp)
{
int i,j;
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_SYMTAB) {
continue;
}
sec->symtab = malloc(sec->shdr.sh_size);
if (!sec->symtab) {
die("malloc of %d bytes for symtab failed\n",
sec->shdr.sh_size);
}
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
sec->shdr.sh_offset, strerror(errno));
}
if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
!= sec->shdr.sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
Elf32_Sym *sym = &sec->symtab[j];
sym->st_name = elf32_to_cpu(sym->st_name);
sym->st_value = elf32_to_cpu(sym->st_value);
sym->st_size = elf32_to_cpu(sym->st_size);
sym->st_shndx = elf16_to_cpu(sym->st_shndx);
}
}
}
static void read_relocs(FILE *fp)
{
int i,j;
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_REL) {
continue;
}
sec->reltab = malloc(sec->shdr.sh_size);
if (!sec->reltab) {
die("malloc of %d bytes for relocs failed\n",
sec->shdr.sh_size);
}
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
sec->shdr.sh_offset, strerror(errno));
}
if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
!= sec->shdr.sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
Elf32_Rel *rel = &sec->reltab[j];
rel->r_offset = elf32_to_cpu(rel->r_offset);
rel->r_info = elf32_to_cpu(rel->r_info);
}
}
}
static void print_absolute_symbols(void)
{
int i;
printf("Absolute symbols\n");
printf(" Num: Value Size Type Bind Visibility Name\n");
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
char *sym_strtab;
int j;
if (sec->shdr.sh_type != SHT_SYMTAB) {
continue;
}
sym_strtab = sec->link->strtab;
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
Elf32_Sym *sym;
const char *name;
sym = &sec->symtab[j];
name = sym_name(sym_strtab, sym);
if (sym->st_shndx != SHN_ABS) {
continue;
}
printf("%5d %08x %5d %10s %10s %12s %s\n",
j, sym->st_value, sym->st_size,
sym_type(ELF32_ST_TYPE(sym->st_info)),
sym_bind(ELF32_ST_BIND(sym->st_info)),
sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
name);
}
}
printf("\n");
}
static void print_absolute_relocs(void)
{
int i, printed = 0;
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
struct section *sec_applies, *sec_symtab;
char *sym_strtab;
Elf32_Sym *sh_symtab;
int j;
if (sec->shdr.sh_type != SHT_REL) {
continue;
}
sec_symtab = sec->link;
sec_applies = &secs[sec->shdr.sh_info];
if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = sec_symtab->symtab;
sym_strtab = sec_symtab->link->strtab;
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
Elf32_Rel *rel;
Elf32_Sym *sym;
const char *name;
rel = &sec->reltab[j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
name = sym_name(sym_strtab, sym);
if (sym->st_shndx != SHN_ABS) {
continue;
}
/* Absolute symbols are not relocated if bzImage is
* loaded at a non-compiled address. Display a warning
* to user at compile time about the absolute
* relocations present.
*
* User need to audit the code to make sure
* some symbols which should have been section
* relative have not become absolute because of some
* linker optimization or wrong programming usage.
*
* Before warning check if this absolute symbol
* relocation is harmless.
*/
if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
continue;
if (!printed) {
printf("WARNING: Absolute relocations"
" present\n");
printf("Offset Info Type Sym.Value "
"Sym.Name\n");
printed = 1;
}
printf("%08x %08x %10s %08x %s\n",
rel->r_offset,
rel->r_info,
rel_type(ELF32_R_TYPE(rel->r_info)),
sym->st_value,
name);
}
}
if (printed)
printf("\n");
}
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
int use_real_mode)
{
int i;
/* Walk through the relocations */
for (i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
struct section *sec_applies, *sec_symtab;
int j;
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_REL) {
continue;
}
sec_symtab = sec->link;
sec_applies = &secs[sec->shdr.sh_info];
if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = sec_symtab->symtab;
sym_strtab = sec_symtab->link->strtab;
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
Elf32_Rel *rel;
Elf32_Sym *sym;
unsigned r_type;
const char *symname;
int shn_abs;
rel = &sec->reltab[j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info);
shn_abs = sym->st_shndx == SHN_ABS;
switch (r_type) {
case R_386_NONE:
case R_386_PC32:
case R_386_PC16:
case R_386_PC8:
/*
* NONE can be ignored and and PC relative
* relocations don't need to be adjusted.
*/
break;
case R_386_16:
symname = sym_name(sym_strtab, sym);
if (!use_real_mode)
goto bad;
if (shn_abs) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_SEG, symname))
goto bad;
} else {
if (is_reloc(S_LIN, symname))
goto bad;
else
break;
}
visit(rel, sym);
break;
case R_386_32:
symname = sym_name(sym_strtab, sym);
if (shn_abs) {
if (is_reloc(S_ABS, symname))
break;
else if (!is_reloc(S_REL, symname))
goto bad;
} else {
if (use_real_mode &&
!is_reloc(S_LIN, symname))
break;
}
visit(rel, sym);
break;
default:
die("Unsupported relocation type: %s (%d)\n",
rel_type(r_type), r_type);
break;
bad:
symname = sym_name(sym_strtab, sym);
die("Invalid %s %s relocation: %s\n",
shn_abs ? "absolute" : "relative",
rel_type(r_type), symname);
}
}
}
}
static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
if (ELF32_R_TYPE(rel->r_info) == R_386_16)
reloc16_count++;
else
reloc_count++;
}
static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
/* Remember the address that needs to be adjusted. */
if (ELF32_R_TYPE(rel->r_info) == R_386_16)
relocs16[reloc16_idx++] = rel->r_offset;
else
relocs[reloc_idx++] = rel->r_offset;
}
static int cmp_relocs(const void *va, const void *vb)
{
const unsigned long *a, *b;
a = va; b = vb;
return (*a == *b)? 0 : (*a > *b)? 1 : -1;
}
static int write32(unsigned int v, FILE *f)
{
unsigned char buf[4];
put_unaligned_le32(v, buf);
return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
}
static void emit_relocs(int as_text, int use_real_mode)
{
int i;
/* Count how many relocations I have and allocate space for them. */
reloc_count = 0;
walk_relocs(count_reloc, use_real_mode);
relocs = malloc(reloc_count * sizeof(relocs[0]));
if (!relocs) {
die("malloc of %d entries for relocs failed\n",
reloc_count);
}
relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
if (!relocs16) {
die("malloc of %d entries for relocs16 failed\n",
reloc16_count);
}
/* Collect up the relocations */
reloc_idx = 0;
walk_relocs(collect_reloc, use_real_mode);
if (reloc16_count && !use_real_mode)
die("Segment relocations found but --realmode not specified\n");
/* Order the relocations for more efficient processing */
qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
/* Print the relocations */
if (as_text) {
/* Print the relocations in a form suitable that
* gas will like.
*/
printf(".section \".data.reloc\",\"a\"\n");
printf(".balign 4\n");
if (use_real_mode) {
printf("\t.long %lu\n", reloc16_count);
for (i = 0; i < reloc16_count; i++)
printf("\t.long 0x%08lx\n", relocs16[i]);
printf("\t.long %lu\n", reloc_count);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
} else {
/* Print a stop */
printf("\t.long 0x%08lx\n", (unsigned long)0);
for (i = 0; i < reloc_count; i++) {
printf("\t.long 0x%08lx\n", relocs[i]);
}
}
printf("\n");
}
else {
if (use_real_mode) {
write32(reloc16_count, stdout);
for (i = 0; i < reloc16_count; i++)
write32(relocs16[i], stdout);
write32(reloc_count, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++)
write32(relocs[i], stdout);
} else {
/* Print a stop */
write32(0, stdout);
/* Now print each relocation */
for (i = 0; i < reloc_count; i++) {
write32(relocs[i], stdout);
}
}
}
}
static void usage(void)
{
die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
}
int main(int argc, char **argv)
{
int show_absolute_syms, show_absolute_relocs;
int as_text, use_real_mode;
const char *fname;
FILE *fp;
int i;
show_absolute_syms = 0;
show_absolute_relocs = 0;
as_text = 0;
use_real_mode = 0;
fname = NULL;
for (i = 1; i < argc; i++) {
char *arg = argv[i];
if (*arg == '-') {
if (strcmp(arg, "--abs-syms") == 0) {
show_absolute_syms = 1;
continue;
}
if (strcmp(arg, "--abs-relocs") == 0) {
show_absolute_relocs = 1;
continue;
}
if (strcmp(arg, "--text") == 0) {
as_text = 1;
continue;
}
if (strcmp(arg, "--realmode") == 0) {
use_real_mode = 1;
continue;
}
}
else if (!fname) {
fname = arg;
continue;
}
usage();
}
if (!fname) {
usage();
}
regex_init(use_real_mode);
fp = fopen(fname, "r");
if (!fp) {
die("Cannot open %s: %s\n",
fname, strerror(errno));
}
read_ehdr(fp);
read_shdrs(fp);
read_strtabs(fp);
read_symtabs(fp);
read_relocs(fp);
if (show_absolute_syms) {
print_absolute_symbols();
return 0;
}
if (show_absolute_relocs) {
print_absolute_relocs();
return 0;
}
emit_relocs(as_text, use_real_mode);
return 0;
}
