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x86: remove arbitrary ELF section limit in i386 relocatable kernel
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Impact: build failure in maximal configurations

The 32-bit x86 relocatable kernel requires an auxilliary host program
to process the relocations.  This program had a hard-coded arbitrary
limit of a 100 ELF sections.  Instead of a hard-coded limit, allocate
the structures dynamically.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
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H. Peter Anvin committed Jul 1, 2008
1 parent aa60d13 commit 908ec7a
Showing 1 changed file with 110 additions and 88 deletions.
198 changes: 110 additions & 88 deletions arch/x86/boot/compressed/relocs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,16 +10,20 @@
#define USE_BSD
#include <endian.h>

#define MAX_SHDRS 100
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
static Elf32_Ehdr ehdr;
static Elf32_Shdr shdr[MAX_SHDRS];
static Elf32_Sym *symtab[MAX_SHDRS];
static Elf32_Rel *reltab[MAX_SHDRS];
static char *strtab[MAX_SHDRS];
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;

struct section {
Elf32_Shdr shdr;
struct section *link;
Elf32_Sym *symtab;
Elf32_Rel *reltab;
char *strtab;
};
static struct section *secs;

/*
* Following symbols have been audited. There values are constant and do
* not change if bzImage is loaded at a different physical address than
Expand All @@ -35,7 +39,7 @@ static int is_safe_abs_reloc(const char* sym_name)
{
int i;

for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
for (i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
if (!strcmp(sym_name, safe_abs_relocs[i]))
/* Match found */
return 1;
Expand Down Expand Up @@ -137,10 +141,10 @@ static const char *sec_name(unsigned shndx)
{
const char *sec_strtab;
const char *name;
sec_strtab = strtab[ehdr.e_shstrndx];
sec_strtab = secs[ehdr.e_shstrndx].strtab;
name = "<noname>";
if (shndx < ehdr.e_shnum) {
name = sec_strtab + shdr[shndx].sh_name;
name = sec_strtab + secs[shndx].shdr.sh_name;
}
else if (shndx == SHN_ABS) {
name = "ABSOLUTE";
Expand All @@ -159,7 +163,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
name = sym_strtab + sym->st_name;
}
else {
name = sec_name(shdr[sym->st_shndx].sh_name);
name = sec_name(secs[sym->st_shndx].shdr.sh_name);
}
return name;
}
Expand Down Expand Up @@ -244,50 +248,57 @@ static void read_ehdr(FILE *fp)
static void read_shdrs(FILE *fp)
{
int i;
if (ehdr.e_shnum > MAX_SHDRS) {
die("%d section headers supported: %d\n",
ehdr.e_shnum, MAX_SHDRS);
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));
}
if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
die("Cannot read ELF section headers: %s\n",
strerror(errno));
}
for(i = 0; i < ehdr.e_shnum; i++) {
shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
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++) {
if (shdr[i].sh_type != SHT_STRTAB) {
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_STRTAB) {
continue;
}
strtab[i] = malloc(shdr[i].sh_size);
if (!strtab[i]) {
sec->strtab = malloc(sec->shdr.sh_size);
if (!sec->strtab) {
die("malloc of %d bytes for strtab failed\n",
shdr[i].sh_size);
sec->shdr.sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
sec->shdr.sh_offset, strerror(errno));
}
if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
!= sec->shdr.sh_size) {
die("Cannot read symbol table: %s\n",
strerror(errno));
}
Expand All @@ -297,28 +308,31 @@ static void read_strtabs(FILE *fp)
static void read_symtabs(FILE *fp)
{
int i,j;
for(i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type != SHT_SYMTAB) {
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_SYMTAB) {
continue;
}
symtab[i] = malloc(shdr[i].sh_size);
if (!symtab[i]) {
sec->symtab = malloc(sec->shdr.sh_size);
if (!sec->symtab) {
die("malloc of %d bytes for symtab failed\n",
shdr[i].sh_size);
sec->shdr.sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
sec->shdr.sh_offset, strerror(errno));
}
if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
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 < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
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);
}
}
}
Expand All @@ -327,26 +341,29 @@ static void read_symtabs(FILE *fp)
static void read_relocs(FILE *fp)
{
int i,j;
for(i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type != SHT_REL) {
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_REL) {
continue;
}
reltab[i] = malloc(shdr[i].sh_size);
if (!reltab[i]) {
sec->reltab = malloc(sec->shdr.sh_size);
if (!sec->reltab) {
die("malloc of %d bytes for relocs failed\n",
shdr[i].sh_size);
sec->shdr.sh_size);
}
if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
die("Seek to %d failed: %s\n",
shdr[i].sh_offset, strerror(errno));
sec->shdr.sh_offset, strerror(errno));
}
if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
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 < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
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);
}
}
}
Expand All @@ -357,19 +374,21 @@ 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++) {
for (i = 0; i < ehdr.e_shnum; i++) {
struct section *sec = &secs[i];
char *sym_strtab;
Elf32_Sym *sh_symtab;
int j;
if (shdr[i].sh_type != SHT_SYMTAB) {

if (sec->shdr.sh_type != SHT_SYMTAB) {
continue;
}
sh_symtab = symtab[i];
sym_strtab = strtab[shdr[i].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
sh_symtab = sec->symtab;
sym_strtab = sec->link->strtab;
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
Elf32_Sym *sym;
const char *name;
sym = &symtab[i][j];
sym = &sec->symtab[j];
name = sym_name(sym_strtab, sym);
if (sym->st_shndx != SHN_ABS) {
continue;
Expand All @@ -389,26 +408,27 @@ static void print_absolute_relocs(void)
{
int i, printed = 0;

for(i = 0; i < ehdr.e_shnum; i++) {
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;
unsigned sec_applies, sec_symtab;
int j;
if (shdr[i].sh_type != SHT_REL) {
if (sec->shdr.sh_type != SHT_REL) {
continue;
}
sec_symtab = shdr[i].sh_link;
sec_applies = shdr[i].sh_info;
if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
sec_symtab = sec->link;
sec_applies = &secs[sec->shdr.sh_info];
if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = symtab[sec_symtab];
sym_strtab = strtab[shdr[sec_symtab].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
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 = &reltab[i][j];
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) {
Expand Down Expand Up @@ -456,26 +476,28 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
{
int i;
/* Walk through the relocations */
for(i = 0; i < ehdr.e_shnum; i++) {
for (i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
unsigned sec_applies, sec_symtab;
struct section *sec_applies, *sec_symtab;
int j;
if (shdr[i].sh_type != SHT_REL) {
struct section *sec = &secs[i];

if (sec->shdr.sh_type != SHT_REL) {
continue;
}
sec_symtab = shdr[i].sh_link;
sec_applies = shdr[i].sh_info;
if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
sec_symtab = sec->link;
sec_applies = &secs[sec->shdr.sh_info];
if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
continue;
}
sh_symtab = symtab[sec_symtab];
sym_strtab = strtab[shdr[sec_symtab].sh_link];
for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
sh_symtab = sec_symtab->symtab;
sym_strtab = sec->link->strtab;
for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
Elf32_Rel *rel;
Elf32_Sym *sym;
unsigned r_type;
rel = &reltab[i][j];
rel = &sec->reltab[j];
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info);
/* Don't visit relocations to absolute symbols */
Expand Down Expand Up @@ -539,7 +561,7 @@ static void emit_relocs(int as_text)
*/
printf(".section \".data.reloc\",\"a\"\n");
printf(".balign 4\n");
for(i = 0; i < reloc_count; i++) {
for (i = 0; i < reloc_count; i++) {
printf("\t .long 0x%08lx\n", relocs[i]);
}
printf("\n");
Expand All @@ -550,7 +572,7 @@ static void emit_relocs(int as_text)
/* Print a stop */
printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
/* Now print each relocation */
for(i = 0; i < reloc_count; i++) {
for (i = 0; i < reloc_count; i++) {
buf[0] = (relocs[i] >> 0) & 0xff;
buf[1] = (relocs[i] >> 8) & 0xff;
buf[2] = (relocs[i] >> 16) & 0xff;
Expand All @@ -577,7 +599,7 @@ int main(int argc, char **argv)
show_absolute_relocs = 0;
as_text = 0;
fname = NULL;
for(i = 1; i < argc; i++) {
for (i = 1; i < argc; i++) {
char *arg = argv[i];
if (*arg == '-') {
if (strcmp(argv[1], "--abs-syms") == 0) {
Expand Down

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