arch/x86/boot/compressed/relocs.c - kernel/msm-4.9 - Gitiles

 #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>

 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;

 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
  * the address for which it has been compiled. Don't warn user about
  * absolute relocations present w.r.t these symbols.
  */
 static const char abs_sym_regex[] =
 	"^(xen_irq_disable_direct_reloc$|"
 	"xen_save_fl_direct_reloc$|"
 	"VDSO|"
 	"__crc_)";
 static regex_t abs_sym_regex_c;
 static int is_abs_reloc(const char *sym_name)
 {
 	return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0);
 }

 /*
  * These symbols are known to be relative, even if the linker marks them
  * as absolute (typically defined outside any section in the linker script.)
  */
 static const char rel_sym_regex[] =
 	"^_end$";
 static regex_t rel_sym_regex_c;
 static int is_rel_reloc(const char *sym_name)
 {
 	return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0);
 }

 static void regex_init(void)
 {
         char errbuf[128];
         int err;

         err = regcomp(&abs_sym_regex_c, abs_sym_regex,
                       REG_EXTENDED|REG_NOSUB);
         if (err) {
                 regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf);
                 die("%s", errbuf);
         }

         err = regcomp(&rel_sym_regex_c, rel_sym_regex,
                       REG_EXTENDED|REG_NOSUB);
         if (err) {
                 regerror(err, &rel_sym_regex_c, 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),
 #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(secs[sym->st_shndx].shdr.sh_name);
 	}
 	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;
 		Elf32_Sym *sh_symtab;
 		int j;

 		if (sec->shdr.sh_type != SHT_SYMTAB) {
 			continue;
 		}
 		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 = &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_abs_reloc(name) || is_rel_reloc(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 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;
 			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 */
 			if (sym->st_shndx == SHN_ABS &&
 			    !is_rel_reloc(sym_name(sym_strtab, sym))) {
 				continue;
 			}
 			switch (r_type) {
 			case R_386_NONE:
 			case R_386_PC32:
 				/*
 				 * NONE can be ignored and and PC relative
 				 * relocations don't need to be adjusted.
 				 */
 				break;
 			case R_386_32:
 				/* Visit relocations that need to be adjusted */
 				visit(rel, sym);
 				break;
 			default:
 				die("Unsupported relocation type: %s (%d)\n",
 				    rel_type(r_type), r_type);
 				break;
 			}
 		}
 	}
 }

 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 {
 	reloc_count += 1;
 }

 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 {
 	/* Remember the address that needs to be adjusted. */
 	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 void emit_relocs(int as_text)
 {
 	int i;
 	/* Count how many relocations I have and allocate space for them. */
 	reloc_count = 0;
 	walk_relocs(count_reloc);
 	relocs = malloc(reloc_count * sizeof(relocs[0]));
 	if (!relocs) {
 		die("malloc of %d entries for relocs failed\n",
 			reloc_count);
 	}
 	/* Collect up the relocations */
 	reloc_idx = 0;
 	walk_relocs(collect_reloc);

 	/* Order the relocations for more efficient processing */
 	qsort(relocs, reloc_count, sizeof(relocs[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");
 		for (i = 0; i < reloc_count; i++) {
 			printf("\t .long 0x%08lx\n", relocs[i]);
 		}
 		printf("\n");
 	}
 	else {
 		unsigned char buf[4];
 		/* Print a stop */
 		fwrite("\0\0\0\0", 4, 1, stdout);
 		/* Now print each relocation */
 		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;
 			buf[3] = (relocs[i] >> 24) & 0xff;
 			fwrite(buf, 4, 1, stdout);
 		}
 	}
 }

 static void usage(void)
 {
 	die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
 }

 int main(int argc, char **argv)
 {
 	int show_absolute_syms, show_absolute_relocs;
 	int as_text;
 	const char *fname;
 	FILE *fp;
 	int i;

 	regex_init();

 	show_absolute_syms = 0;
 	show_absolute_relocs = 0;
 	as_text = 0;
 	fname = NULL;
 	for (i = 1; i < argc; i++) {
 		char *arg = argv[i];
 		if (*arg == '-') {
 			if (strcmp(argv[1], "--abs-syms") == 0) {
 				show_absolute_syms = 1;
 				continue;
 			}

 			if (strcmp(argv[1], "--abs-relocs") == 0) {
 				show_absolute_relocs = 1;
 				continue;
 			}
 			else if (strcmp(argv[1], "--text") == 0) {
 				as_text = 1;
 				continue;
 			}
 		}
 		else if (!fname) {
 			fname = arg;
 			continue;
 		}
 		usage();
 	}
 	if (!fname) {
 		usage();
 	}
 	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);
 	return 0;
 }
	#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>

	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;

	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
	* the address for which it has been compiled. Don't warn user about
	* absolute relocations present w.r.t these symbols.
	*/
	static const char abs_sym_regex[] =
	"^(xen_irq_disable_direct_reloc$\|"
	"xen_save_fl_direct_reloc$\|"
	"VDSO\|"
	"__crc_)";
	static regex_t abs_sym_regex_c;
	static int is_abs_reloc(const char *sym_name)
	{
	return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0);
	}

	/*
	* These symbols are known to be relative, even if the linker marks them
	* as absolute (typically defined outside any section in the linker script.)
	*/
	static const char rel_sym_regex[] =
	"^_end$";
	static regex_t rel_sym_regex_c;
	static int is_rel_reloc(const char *sym_name)
	{
	return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0);
	}

	static void regex_init(void)
	{
	char errbuf[128];
	int err;

	err = regcomp(&abs_sym_regex_c, abs_sym_regex,
	REG_EXTENDED\|REG_NOSUB);
	if (err) {
	regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf);
	die("%s", errbuf);
	}

	err = regcomp(&rel_sym_regex_c, rel_sym_regex,
	REG_EXTENDED\|REG_NOSUB);
	if (err) {
	regerror(err, &rel_sym_regex_c, 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),
	#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(secs[sym->st_shndx].shdr.sh_name);
	}
	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;
	Elf32_Sym *sh_symtab;
	int j;

	if (sec->shdr.sh_type != SHT_SYMTAB) {
	continue;
	}
	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 = &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_abs_reloc(name) \|\| is_rel_reloc(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 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;
	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 */
	if (sym->st_shndx == SHN_ABS &&
	!is_rel_reloc(sym_name(sym_strtab, sym))) {
	continue;
	}
	switch (r_type) {
	case R_386_NONE:
	case R_386_PC32:
	/*
	* NONE can be ignored and and PC relative
	* relocations don't need to be adjusted.
	*/
	break;
	case R_386_32:
	/* Visit relocations that need to be adjusted */
	visit(rel, sym);
	break;
	default:
	die("Unsupported relocation type: %s (%d)\n",
	rel_type(r_type), r_type);
	break;
	}
	}
	}
	}

	static void count_reloc(Elf32_Rel rel, Elf32_Sym sym)
	{
	reloc_count += 1;
	}

	static void collect_reloc(Elf32_Rel rel, Elf32_Sym sym)
	{
	/* Remember the address that needs to be adjusted. */
	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 void emit_relocs(int as_text)
	{
	int i;
	/* Count how many relocations I have and allocate space for them. */
	reloc_count = 0;
	walk_relocs(count_reloc);
	relocs = malloc(reloc_count * sizeof(relocs[0]));
	if (!relocs) {
	die("malloc of %d entries for relocs failed\n",
	reloc_count);
	}
	/* Collect up the relocations */
	reloc_idx = 0;
	walk_relocs(collect_reloc);

	/* Order the relocations for more efficient processing */
	qsort(relocs, reloc_count, sizeof(relocs[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");
	for (i = 0; i < reloc_count; i++) {
	printf("\t .long 0x%08lx\n", relocs[i]);
	}
	printf("\n");
	}
	else {
	unsigned char buf[4];
	/* Print a stop */
	fwrite("\0\0\0\0", 4, 1, stdout);
	/* Now print each relocation */
	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;
	buf[3] = (relocs[i] >> 24) & 0xff;
	fwrite(buf, 4, 1, stdout);
	}
	}
	}

	static void usage(void)
	{
	die("relocs [--abs-syms \|--abs-relocs \| --text] vmlinux\n");
	}

	int main(int argc, char **argv)
	{
	int show_absolute_syms, show_absolute_relocs;
	int as_text;
	const char *fname;
	FILE *fp;
	int i;

	regex_init();

	show_absolute_syms = 0;
	show_absolute_relocs = 0;
	as_text = 0;
	fname = NULL;
	for (i = 1; i < argc; i++) {
	char *arg = argv[i];
	if (*arg == '-') {
	if (strcmp(argv[1], "--abs-syms") == 0) {
	show_absolute_syms = 1;
	continue;
	}

	if (strcmp(argv[1], "--abs-relocs") == 0) {
	show_absolute_relocs = 1;
	continue;
	}
	else if (strcmp(argv[1], "--text") == 0) {
	as_text = 1;
	continue;
	}
	}
	else if (!fname) {
	fname = arg;
	continue;
	}
	usage();
	}
	if (!fname) {
	usage();
	}
	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);
	return 0;
	}