[mirror_ubuntu-zesty-kernel.git] / arch / x86 / boot / compressed / relocs.c

#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>

#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;

/*
 * 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* safe_abs_relocs[] = {
		"__kernel_vsyscall",
		"__kernel_rt_sigreturn",
		"__kernel_sigreturn",
		"SYSENTER_RETURN",
		"VDSO_NOTE_MASK",
		"xen_irq_disable_direct_reloc",
		"xen_save_fl_direct_reloc",
};

static int is_safe_abs_reloc(const char* sym_name)
{
	int i;

	for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
		if (!strcmp(sym_name, safe_abs_relocs[i]))
			/* Match found */
			return 1;
	}
	if (strncmp(sym_name, "__crc_", 6) == 0)
		return 1;
	return 0;
}

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)) {
		name = type_name[type];
	}
	return name;
}

static const char *sec_name(unsigned shndx)
{
	const char *sec_strtab;
	const char *name;
	sec_strtab = strtab[ehdr.e_shstrndx];
	name = "<noname>";
	if (shndx < ehdr.e_shnum) {
		name = sec_strtab + shdr[shndx].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(shdr[sym->st_shndx].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, 4) != 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;
	if (ehdr.e_shnum > MAX_SHDRS) {
		die("%d section headers supported: %d\n",
			ehdr.e_shnum, MAX_SHDRS);
	}
	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);
	}

}

static void read_strtabs(FILE *fp)
{
	int i;
	for(i = 0; i < ehdr.e_shnum; i++) {
		if (shdr[i].sh_type != SHT_STRTAB) {
			continue;
		}
		strtab[i] = malloc(shdr[i].sh_size);
		if (!strtab[i]) {
			die("malloc of %d bytes for strtab failed\n",
				shdr[i].sh_size);
		}
		if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				shdr[i].sh_offset, strerror(errno));
		}
		if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].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++) {
		if (shdr[i].sh_type != SHT_SYMTAB) {
			continue;
		}
		symtab[i] = malloc(shdr[i].sh_size);
		if (!symtab[i]) {
			die("malloc of %d bytes for symtab failed\n",
				shdr[i].sh_size);
		}
		if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				shdr[i].sh_offset, strerror(errno));
		}
		if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].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);
		}
	}
}


static void read_relocs(FILE *fp)
{
	int i,j;
	for(i = 0; i < ehdr.e_shnum; i++) {
		if (shdr[i].sh_type != SHT_REL) {
			continue;
		}
		reltab[i] = malloc(shdr[i].sh_size);
		if (!reltab[i]) {
			die("malloc of %d bytes for relocs failed\n",
				shdr[i].sh_size);
		}
		if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				shdr[i].sh_offset, strerror(errno));
		}
		if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].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);
		}
	}
}


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++) {
		char *sym_strtab;
		Elf32_Sym *sh_symtab;
		int j;
		if (shdr[i].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++) {
			Elf32_Sym *sym;
			const char *name;
			sym = &symtab[i][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++) {
		char *sym_strtab;
		Elf32_Sym *sh_symtab;
		unsigned sec_applies, sec_symtab;
		int j;
		if (shdr[i].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)) {
			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++) {
			Elf32_Rel *rel;
			Elf32_Sym *sym;
			const char *name;
			rel = &reltab[i][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_safe_abs_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;
		unsigned sec_applies, sec_symtab;
		int j;
		if (shdr[i].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)) {
			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++) {
			Elf32_Rel *rel;
			Elf32_Sym *sym;
			unsigned r_type;
			rel = &reltab[i][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) {
				continue;
			}
			if (r_type == R_386_PC32) {
				/* PC relative relocations don't need to be adjusted */
			}
			else if (r_type == R_386_32) {
				/* Visit relocations that need to be adjusted */
				visit(rel, sym);
			}
			else {
				die("Unsupported relocation type: %d\n", r_type);
			}
		}
	}
}

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];
		buf[0] = buf[1] = buf[2] = buf[3] = 0;
		/* 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++) {
			buf[0] = (relocs[i] >>  0) & 0xff;
			buf[1] = (relocs[i] >>  8) & 0xff;
			buf[2] = (relocs[i] >> 16) & 0xff;
			buf[3] = (relocs[i] >> 24) & 0xff;
			printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
		}
	}
}

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;

	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;
}
Commit	Line	Data
968de4f0 EB	1	#include <stdio.h>
	2	#include <stdarg.h>
	3	#include <stdlib.h>
	4	#include <stdint.h>
	5	#include <string.h>
	6	#include <errno.h>
	7	#include <unistd.h>
	8	#include <elf.h>
	9	#include <byteswap.h>
	10	#define USE_BSD
	11	#include <endian.h>
	12
	13	#define MAX_SHDRS 100
ca820181	14	#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
968de4f0 EB	15	static Elf32_Ehdr ehdr;
	16	static Elf32_Shdr shdr[MAX_SHDRS];
	17	static Elf32_Sym *symtab[MAX_SHDRS];
	18	static Elf32_Rel *reltab[MAX_SHDRS];
	19	static char *strtab[MAX_SHDRS];
	20	static unsigned long reloc_count, reloc_idx;
	21	static unsigned long *relocs;
	22
6a044b3a VG	23	/*
	24	* Following symbols have been audited. There values are constant and do
	25	* not change if bzImage is loaded at a different physical address than
	26	* the address for which it has been compiled. Don't warn user about
	27	* absolute relocations present w.r.t these symbols.
	28	*/
	29	static const char* safe_abs_relocs[] = {
	30	"__kernel_vsyscall",
	31	"__kernel_rt_sigreturn",
	32	"__kernel_sigreturn",
	33	"SYSENTER_RETURN",
d2eea68e	34	"VDSO_NOTE_MASK",
600b2fc2 JF	35	"xen_irq_disable_direct_reloc",
600b2fc2 JF	36	"xen_save_fl_direct_reloc",
6a044b3a VG	37	};
	38
	39	static int is_safe_abs_reloc(const char* sym_name)
	40	{
4d022ada	41	int i;
6a044b3a	42
4d022ada	43	for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
6a044b3a VG	44	if (!strcmp(sym_name, safe_abs_relocs[i]))
	45	/* Match found */
	46	return 1;
	47	}
2a3d4f1f AV	48	if (strncmp(sym_name, "__crc_", 6) == 0)
2a3d4f1f AV	49	return 1;
6a044b3a VG	50	return 0;
	51	}
	52
968de4f0 EB	53	static void die(char *fmt, ...)
	54	{
	55	va_list ap;
	56	va_start(ap, fmt);
	57	vfprintf(stderr, fmt, ap);
	58	va_end(ap);
	59	exit(1);
	60	}
	61
	62	static const char *sym_type(unsigned type)
	63	{
	64	static const char *type_name[] = {
	65	#define SYM_TYPE(X) [X] = #X
	66	SYM_TYPE(STT_NOTYPE),
	67	SYM_TYPE(STT_OBJECT),
	68	SYM_TYPE(STT_FUNC),
	69	SYM_TYPE(STT_SECTION),
	70	SYM_TYPE(STT_FILE),
	71	SYM_TYPE(STT_COMMON),
	72	SYM_TYPE(STT_TLS),
	73	#undef SYM_TYPE
	74	};
	75	const char *name = "unknown sym type name";
ca820181	76	if (type < ARRAY_SIZE(type_name)) {
968de4f0 EB	77	name = type_name[type];
	78	}
	79	return name;
	80	}
	81
	82	static const char *sym_bind(unsigned bind)
	83	{
	84	static const char *bind_name[] = {
	85	#define SYM_BIND(X) [X] = #X
	86	SYM_BIND(STB_LOCAL),
	87	SYM_BIND(STB_GLOBAL),
	88	SYM_BIND(STB_WEAK),
	89	#undef SYM_BIND
	90	};
	91	const char *name = "unknown sym bind name";
ca820181	92	if (bind < ARRAY_SIZE(bind_name)) {
968de4f0 EB	93	name = bind_name[bind];
	94	}
	95	return name;
	96	}
	97
	98	static const char *sym_visibility(unsigned visibility)
	99	{
	100	static const char *visibility_name[] = {
	101	#define SYM_VISIBILITY(X) [X] = #X
	102	SYM_VISIBILITY(STV_DEFAULT),
	103	SYM_VISIBILITY(STV_INTERNAL),
	104	SYM_VISIBILITY(STV_HIDDEN),
	105	SYM_VISIBILITY(STV_PROTECTED),
	106	#undef SYM_VISIBILITY
	107	};
	108	const char *name = "unknown sym visibility name";
ca820181	109	if (visibility < ARRAY_SIZE(visibility_name)) {
968de4f0 EB	110	name = visibility_name[visibility];
	111	}
	112	return name;
	113	}
	114
	115	static const char *rel_type(unsigned type)
	116	{
	117	static const char *type_name[] = {
	118	#define REL_TYPE(X) [X] = #X
	119	REL_TYPE(R_386_NONE),
	120	REL_TYPE(R_386_32),
	121	REL_TYPE(R_386_PC32),
	122	REL_TYPE(R_386_GOT32),
	123	REL_TYPE(R_386_PLT32),
	124	REL_TYPE(R_386_COPY),
	125	REL_TYPE(R_386_GLOB_DAT),
	126	REL_TYPE(R_386_JMP_SLOT),
	127	REL_TYPE(R_386_RELATIVE),
	128	REL_TYPE(R_386_GOTOFF),
	129	REL_TYPE(R_386_GOTPC),
	130	#undef REL_TYPE
	131	};
	132	const char *name = "unknown type rel type name";
ca820181	133	if (type < ARRAY_SIZE(type_name)) {
968de4f0 EB	134	name = type_name[type];
	135	}
	136	return name;
	137	}
	138
	139	static const char *sec_name(unsigned shndx)
	140	{
	141	const char *sec_strtab;
	142	const char *name;
	143	sec_strtab = strtab[ehdr.e_shstrndx];
	144	name = "<noname>";
	145	if (shndx < ehdr.e_shnum) {
	146	name = sec_strtab + shdr[shndx].sh_name;
	147	}
	148	else if (shndx == SHN_ABS) {
	149	name = "ABSOLUTE";
	150	}
	151	else if (shndx == SHN_COMMON) {
	152	name = "COMMON";
	153	}
	154	return name;
	155	}
	156
	157	static const char sym_name(const char sym_strtab, Elf32_Sym *sym)
	158	{
	159	const char *name;
	160	name = "<noname>";
	161	if (sym->st_name) {
	162	name = sym_strtab + sym->st_name;
	163	}
	164	else {
	165	name = sec_name(shdr[sym->st_shndx].sh_name);
	166	}
	167	return name;
	168	}
	169
	170
	171
	172	#if BYTE_ORDER == LITTLE_ENDIAN
	173	#define le16_to_cpu(val) (val)
	174	#define le32_to_cpu(val) (val)
	175	#endif
	176	#if BYTE_ORDER == BIG_ENDIAN
	177	#define le16_to_cpu(val) bswap_16(val)
	178	#define le32_to_cpu(val) bswap_32(val)
	179	#endif
	180
	181	static uint16_t elf16_to_cpu(uint16_t val)
	182	{
	183	return le16_to_cpu(val);
	184	}
	185
	186	static uint32_t elf32_to_cpu(uint32_t val)
	187	{
	188	return le32_to_cpu(val);
	189	}
	190
	191	static void read_ehdr(FILE *fp)
	192	{
	193	if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
	194	die("Cannot read ELF header: %s\n",
	195	strerror(errno));
	196	}
	197	if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
198	die("No ELF magic\n");
199	}
200	if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
201	die("Not a 32 bit executable\n");
202	}
203	if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
204	die("Not a LSB ELF executable\n");
205	}
206	if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
207	die("Unknown ELF version\n");
208	}
209	/* Convert the fields to native endian */
210	ehdr.e_type = elf16_to_cpu(ehdr.e_type);
211	ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
212	ehdr.e_version = elf32_to_cpu(ehdr.e_version);
213	ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
214	ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
215	ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
216	ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
217	ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
218	ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
219	ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
220	ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
221	ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
222	ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
223
224	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
225	die("Unsupported ELF header type\n");
226	}
227	if (ehdr.e_machine != EM_386) {
228	die("Not for x86\n");
229	}
230	if (ehdr.e_version != EV_CURRENT) {
231	die("Unknown ELF version\n");
232	}
233	if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
234	die("Bad Elf header size\n");
235	}
236	if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
237	die("Bad program header entry\n");
238	}
239	if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
240	die("Bad section header entry\n");
241	}
242	if (ehdr.e_shstrndx >= ehdr.e_shnum) {
243	die("String table index out of bounds\n");
244	}
245	}
246
247	static void read_shdrs(FILE *fp)
248	{
249	int i;
250	if (ehdr.e_shnum > MAX_SHDRS) {
251	die("%d section headers supported: %d\n",
252	ehdr.e_shnum, MAX_SHDRS);
253	}
254	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
255	die("Seek to %d failed: %s\n",
256	ehdr.e_shoff, strerror(errno));
257	}
258	if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
259	die("Cannot read ELF section headers: %s\n",
260	strerror(errno));
261	}
262	for(i = 0; i < ehdr.e_shnum; i++) {
263	shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
264	shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
265	shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
266	shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
267	shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
268	shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
269	shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
270	shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
271	shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
272	shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
273	}
274
275	}
276
277	static void read_strtabs(FILE *fp)
278	{
279	int i;
280	for(i = 0; i < ehdr.e_shnum; i++) {
281	if (shdr[i].sh_type != SHT_STRTAB) {
282	continue;
283	}
284	strtab[i] = malloc(shdr[i].sh_size);
285	if (!strtab[i]) {
286	die("malloc of %d bytes for strtab failed\n",
287	shdr[i].sh_size);
288	}
289	if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
290	die("Seek to %d failed: %s\n",
291	shdr[i].sh_offset, strerror(errno));
292	}
293	if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
294	die("Cannot read symbol table: %s\n",
295	strerror(errno));
296	}
297	}
298	}
299
300	static void read_symtabs(FILE *fp)
301	{
302	int i,j;
303	for(i = 0; i < ehdr.e_shnum; i++) {
304	if (shdr[i].sh_type != SHT_SYMTAB) {
305	continue;
306	}
307	symtab[i] = malloc(shdr[i].sh_size);
308	if (!symtab[i]) {
309	die("malloc of %d bytes for symtab failed\n",
310	shdr[i].sh_size);
311	}
312	if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
313	die("Seek to %d failed: %s\n",
314	shdr[i].sh_offset, strerror(errno));
315	}
316	if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
317	die("Cannot read symbol table: %s\n",
318	strerror(errno));
319	}
320	for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
321	symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
322	symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
323	symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
324	symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
325	}
326	}
327	}
328
329
330	static void read_relocs(FILE *fp)
331	{
332	int i,j;
333	for(i = 0; i < ehdr.e_shnum; i++) {
334	if (shdr[i].sh_type != SHT_REL) {
335	continue;
336	}
337	reltab[i] = malloc(shdr[i].sh_size);
338	if (!reltab[i]) {
339	die("malloc of %d bytes for relocs failed\n",
340	shdr[i].sh_size);
341	}
342	if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
343	die("Seek to %d failed: %s\n",
344	shdr[i].sh_offset, strerror(errno));
345	}
346	if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
347	die("Cannot read symbol table: %s\n",
348	strerror(errno));
349	}
350	for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
351	reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
352	reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
353	}
354	}
355	}
356
357
358	static void print_absolute_symbols(void)
359	{
360	int i;
361	printf("Absolute symbols\n");
362	printf(" Num: Value Size Type Bind Visibility Name\n");
363	for(i = 0; i < ehdr.e_shnum; i++) {
364	char *sym_strtab;
365	Elf32_Sym *sh_symtab;
366	int j;
367	if (shdr[i].sh_type != SHT_SYMTAB) {
368	continue;
369	}
370	sh_symtab = symtab[i];
371	sym_strtab = strtab[shdr[i].sh_link];
372	for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
373	Elf32_Sym *sym;
374	const char *name;
375	sym = &symtab[i][j];
376	name = sym_name(sym_strtab, sym);
377	if (sym->st_shndx != SHN_ABS) {
378	continue;
379	}
380	printf("%5d %08x %5d %10s %10s %12s %s\n",
381	j, sym->st_value, sym->st_size,
382	sym_type(ELF32_ST_TYPE(sym->st_info)),
383	sym_bind(ELF32_ST_BIND(sym->st_info)),
384	sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
385	name);
386	}
387	}
388	printf("\n");
389	}
390
391	static void print_absolute_relocs(void)
392	{
6a044b3a VG	393	int i, printed = 0;
6a044b3a VG	394
968de4f0 EB	395	for(i = 0; i < ehdr.e_shnum; i++) {
	396	char *sym_strtab;
	397	Elf32_Sym *sh_symtab;
	398	unsigned sec_applies, sec_symtab;
	399	int j;
	400	if (shdr[i].sh_type != SHT_REL) {
	401	continue;
	402	}
	403	sec_symtab = shdr[i].sh_link;
	404	sec_applies = shdr[i].sh_info;
	405	if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
	406	continue;
	407	}
	408	sh_symtab = symtab[sec_symtab];
	409	sym_strtab = strtab[shdr[sec_symtab].sh_link];
	410	for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
	411	Elf32_Rel *rel;
	412	Elf32_Sym *sym;
	413	const char *name;
	414	rel = &reltab[i][j];
	415	sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
	416	name = sym_name(sym_strtab, sym);
	417	if (sym->st_shndx != SHN_ABS) {
	418	continue;
	419	}
6a044b3a VG	420
	421	/* Absolute symbols are not relocated if bzImage is
	422	* loaded at a non-compiled address. Display a warning
	423	* to user at compile time about the absolute
	424	* relocations present.
	425	*
	426	* User need to audit the code to make sure
	427	* some symbols which should have been section
	428	* relative have not become absolute because of some
	429	* linker optimization or wrong programming usage.
	430	*
	431	* Before warning check if this absolute symbol
	432	* relocation is harmless.
	433	*/
	434	if (is_safe_abs_reloc(name))
	435	continue;
	436
	437	if (!printed) {
	438	printf("WARNING: Absolute relocations"
	439	" present\n");
	440	printf("Offset Info Type Sym.Value "
	441	"Sym.Name\n");
	442	printed = 1;
	443	}
	444
968de4f0 EB	445	printf("%08x %08x %10s %08x %s\n",
	446	rel->r_offset,
	447	rel->r_info,
	448	rel_type(ELF32_R_TYPE(rel->r_info)),
	449	sym->st_value,
	450	name);
	451	}
	452	}
6a044b3a VG	453
	454	if (printed)
	455	printf("\n");
968de4f0 EB	456	}
	457
	458	static void walk_relocs(void (visit)(Elf32_Rel rel, Elf32_Sym *sym))
	459	{
	460	int i;
	461	/* Walk through the relocations */
	462	for(i = 0; i < ehdr.e_shnum; i++) {
	463	char *sym_strtab;
	464	Elf32_Sym *sh_symtab;
	465	unsigned sec_applies, sec_symtab;
	466	int j;
	467	if (shdr[i].sh_type != SHT_REL) {
	468	continue;
	469	}
	470	sec_symtab = shdr[i].sh_link;
	471	sec_applies = shdr[i].sh_info;
	472	if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
	473	continue;
	474	}
	475	sh_symtab = symtab[sec_symtab];
	476	sym_strtab = strtab[shdr[sec_symtab].sh_link];
	477	for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
	478	Elf32_Rel *rel;
	479	Elf32_Sym *sym;
	480	unsigned r_type;
	481	rel = &reltab[i][j];
	482	sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
	483	r_type = ELF32_R_TYPE(rel->r_info);
	484	/* Don't visit relocations to absolute symbols */
	485	if (sym->st_shndx == SHN_ABS) {
	486	continue;
	487	}
	488	if (r_type == R_386_PC32) {
	489	/* PC relative relocations don't need to be adjusted */
	490	}
	491	else if (r_type == R_386_32) {
	492	/* Visit relocations that need to be adjusted */
	493	visit(rel, sym);
	494	}
	495	else {
	496	die("Unsupported relocation type: %d\n", r_type);
	497	}
	498	}
	499	}
	500	}
	501
	502	static void count_reloc(Elf32_Rel rel, Elf32_Sym sym)
	503	{
	504	reloc_count += 1;
	505	}
	506
	507	static void collect_reloc(Elf32_Rel rel, Elf32_Sym sym)
	508	{
	509	/* Remember the address that needs to be adjusted. */
	510	relocs[reloc_idx++] = rel->r_offset;
	511	}
	512
	513	static int cmp_relocs(const void va, const void vb)
	514	{
	515	const unsigned long a, b;
	516	a = va; b = vb;
	517	return (a == b)? 0 : (a > b)? 1 : -1;
	518	}
	519
520	static void emit_relocs(int as_text)
521	{
522	int i;
523	/* Count how many relocations I have and allocate space for them. */
524	reloc_count = 0;
525	walk_relocs(count_reloc);
526	relocs = malloc(reloc_count * sizeof(relocs[0]));
527	if (!relocs) {
528	die("malloc of %d entries for relocs failed\n",
529	reloc_count);
530	}
531	/* Collect up the relocations */
532	reloc_idx = 0;
533	walk_relocs(collect_reloc);
534
535	/* Order the relocations for more efficient processing */
536	qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
537
538	/* Print the relocations */
539	if (as_text) {
540	/* Print the relocations in a form suitable that
541	* gas will like.
542	*/
543	printf(".section \".data.reloc\",\"a\"\n");
544	printf(".balign 4\n");
545	for(i = 0; i < reloc_count; i++) {
546	printf("\t .long 0x%08lx\n", relocs[i]);
547	}
548	printf("\n");
549	}
550	else {
551	unsigned char buf[4];
552	buf[0] = buf[1] = buf[2] = buf[3] = 0;
553	/* Print a stop */
554	printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
555	/* Now print each relocation */
556	for(i = 0; i < reloc_count; i++) {
557	buf[0] = (relocs[i] >> 0) & 0xff;
558	buf[1] = (relocs[i] >> 8) & 0xff;
559	buf[2] = (relocs[i] >> 16) & 0xff;
560	buf[3] = (relocs[i] >> 24) & 0xff;
561	printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
562	}
563	}
564	}
565
566	static void usage(void)
567	{
6a044b3a	568	die("relocs [--abs-syms \|--abs-relocs \| --text] vmlinux\n");
968de4f0 EB	569	}
	570
	571	int main(int argc, char **argv)
	572	{
6a044b3a	573	int show_absolute_syms, show_absolute_relocs;
968de4f0 EB	574	int as_text;
	575	const char *fname;
	576	FILE *fp;
	577	int i;
	578
6a044b3a VG	579	show_absolute_syms = 0;
6a044b3a VG	580	show_absolute_relocs = 0;
968de4f0 EB	581	as_text = 0;
	582	fname = NULL;
	583	for(i = 1; i < argc; i++) {
	584	char *arg = argv[i];
	585	if (*arg == '-') {
6a044b3a VG	586	if (strcmp(argv[1], "--abs-syms") == 0) {
	587	show_absolute_syms = 1;
	588	continue;
	589	}
	590
	591	if (strcmp(argv[1], "--abs-relocs") == 0) {
	592	show_absolute_relocs = 1;
968de4f0 EB	593	continue;
	594	}
	595	else if (strcmp(argv[1], "--text") == 0) {
	596	as_text = 1;
	597	continue;
	598	}
	599	}
	600	else if (!fname) {
	601	fname = arg;
	602	continue;
	603	}
	604	usage();
	605	}
	606	if (!fname) {
	607	usage();
	608	}
	609	fp = fopen(fname, "r");
	610	if (!fp) {
	611	die("Cannot open %s: %s\n",
	612	fname, strerror(errno));
	613	}
	614	read_ehdr(fp);
	615	read_shdrs(fp);
	616	read_strtabs(fp);
	617	read_symtabs(fp);
	618	read_relocs(fp);
6a044b3a	619	if (show_absolute_syms) {
968de4f0	620	print_absolute_symbols();
6a044b3a VG	621	return 0;
	622	}
	623	if (show_absolute_relocs) {
968de4f0 EB	624	print_absolute_relocs();
	625	return 0;
	626	}
	627	emit_relocs(as_text);
	628	return 0;
	629	}