modpost.c

Linux Kernel 2.6.9 for OMAP1710

/* Postprocess module symbol versions
 *
 * Copyright 2003       Kai Germaschewski
 *           2002-2003  Rusty Russell, IBM Corporation
 *
 * Based in part on module-init-tools/depmod.c,file2alias
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * Usage: modpost vmlinux module1.o module2.o ...
 */

#include <ctype.h>
#include "modpost.h"

/* Are we using CONFIG_MODVERSIONS? */
int modversions = 0;
/* Warn about undefined symbols? (do so if we have vmlinux) */
int have_vmlinux = 0;

void
fatal(const char *fmt, ...)
{
	va_list arglist;

	fprintf(stderr, "FATAL: ");

	va_start(arglist, fmt);
	vfprintf(stderr, fmt, arglist);
	va_end(arglist);

	exit(1);
}

void
warn(const char *fmt, ...)
{
	va_list arglist;

	fprintf(stderr, "WARNING: ");

	va_start(arglist, fmt);
	vfprintf(stderr, fmt, arglist);
	va_end(arglist);
}

void *do_nofail(void *ptr, const char *file, int line, const char *expr)
{
	if (!ptr) {
		fatal("Memory allocation failure %s line %d: %s.\n",
		      file, line, expr);
	}
	return ptr;
}

/* A list of all modules we processed */

static struct module *modules;

struct module *
find_module(char *modname)
{
	struct module *mod;

	for (mod = modules; mod; mod = mod->next)
		if (strcmp(mod->name, modname) == 0)
			break;
	return mod;
}

struct module *
new_module(char *modname)
{
	struct module *mod;
	char *p, *s;
	
	mod = NOFAIL(malloc(sizeof(*mod)));
	memset(mod, 0, sizeof(*mod));
	p = NOFAIL(strdup(modname));

	/* strip trailing .o */
	if ((s = strrchr(p, '.')) != NULL)
		if (strcmp(s, ".o") == 0)
			*s = '\0';

	/* add to list */
	mod->name = p;
	mod->next = modules;
	modules = mod;

	return mod;
}

/* A hash of all exported symbols,
 * struct symbol is also used for lists of unresolved symbols */

#define SYMBOL_HASH_SIZE 1024

struct symbol {
	struct symbol *next;
	struct module *module;
	unsigned int crc;
	int crc_valid;
	char name[0];
};

static struct symbol *symbolhash[SYMBOL_HASH_SIZE];

/* This is based on the hash agorithm from gdbm, via tdb */
static inline unsigned int tdb_hash(const char *name)
{
	unsigned value;	/* Used to compute the hash value.  */
	unsigned   i;	/* Used to cycle through random values. */

	/* Set the initial value from the key size. */
	for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
		value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));

	return (1103515243 * value + 12345);
}

/* Allocate a new symbols for use in the hash of exported symbols or
 * the list of unresolved symbols per module */

struct symbol *
alloc_symbol(const char *name, struct symbol *next)
{
	struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1));

	memset(s, 0, sizeof(*s));
	strcpy(s->name, name);
	s->next = next;
	return s;
}

/* For the hash of exported symbols */

void
new_symbol(const char *name, struct module *module, unsigned int *crc)
{
	unsigned int hash;
	struct symbol *new;

	hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
	new = symbolhash[hash] = alloc_symbol(name, symbolhash[hash]);
	new->module = module;
	if (crc) {
		new->crc = *crc;
		new->crc_valid = 1;
	}
}

struct symbol *
find_symbol(const char *name)
{
	struct symbol *s;

	/* For our purposes, .foo matches foo.  PPC64 needs this. */
	if (name[0] == '.')
		name++;

	for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) {
		if (strcmp(s->name, name) == 0)
			return s;
	}
	return NULL;
}

/* Add an exported symbol - it may have already been added without a
 * CRC, in this case just update the CRC */
void
add_exported_symbol(const char *name, struct module *module, unsigned int *crc)
{
	struct symbol *s = find_symbol(name);

	if (!s) {
		new_symbol(name, module, crc);
		return;
	}
	if (crc) {
		s->crc = *crc;
		s->crc_valid = 1;
	}
}

void *
grab_file(const char *filename, unsigned long *size)
{
	struct stat st;
	void *map;
	int fd;

	fd = open(filename, O_RDONLY);
	if (fd < 0 || fstat(fd, &st) != 0)
		return NULL;

	*size = st.st_size;
	map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
	close(fd);

	if (map == MAP_FAILED)
		return NULL;
	return map;
}

/*
   Return a copy of the next line in a mmap'ed file.
   spaces in the beginning of the line is trimmed away.
   Return a pointer to a static buffer.
*/
char*
get_next_line(unsigned long *pos, void *file, unsigned long size)
{
	static char line[4096];
	int skip = 1;
	size_t len = 0;
	char *p = (char *)file + *pos;
	char *s = line;

	for (; *pos < size ; (*pos)++)
	{
		if (skip && isspace(*p)) {
			p++;
			continue;
		}
		skip = 0;
		if (*p != '\n' && (*pos < size)) {
			len++;
			*s++ = *p++;
			if (len > 4095)
				break; /* Too long, stop */
		} else {
			/* End of string */
			*s = '\0';
			return line;
		}
	}
	/* End of buffer */
	return NULL;
}

void
release_file(void *file, unsigned long size)
{
	munmap(file, size);
}

void
parse_elf(struct elf_info *info, const char *filename)
{
	unsigned int i;
	Elf_Ehdr *hdr = info->hdr;
	Elf_Shdr *sechdrs;
	Elf_Sym  *sym;

	hdr = grab_file(filename, &info->size);
	if (!hdr) {
		perror(filename);
		abort();
	}
	info->hdr = hdr;
	if (info->size < sizeof(*hdr))
		goto truncated;

	/* Fix endianness in ELF header */
	hdr->e_shoff    = TO_NATIVE(hdr->e_shoff);
	hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx);
	hdr->e_shnum    = TO_NATIVE(hdr->e_shnum);
	hdr->e_machine  = TO_NATIVE(hdr->e_machine);
	sechdrs = (void *)hdr + hdr->e_shoff;
	info->sechdrs = sechdrs;

	/* Fix endianness in section headers */
	for (i = 0; i < hdr->e_shnum; i++) {
		sechdrs[i].sh_type   = TO_NATIVE(sechdrs[i].sh_type);
		sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset);
		sechdrs[i].sh_size   = TO_NATIVE(sechdrs[i].sh_size);
		sechdrs[i].sh_link   = TO_NATIVE(sechdrs[i].sh_link);
		sechdrs[i].sh_name   = TO_NATIVE(sechdrs[i].sh_name);
	}
	/* Find symbol table. */
	for (i = 1; i < hdr->e_shnum; i++) {
		const char *secstrings
			= (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

		if (sechdrs[i].sh_offset > info->size)
			goto truncated;
		if (strcmp(secstrings+sechdrs[i].sh_name, ".modinfo") == 0) {
			info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
			info->modinfo_len = sechdrs[i].sh_size;
		}
		if (sechdrs[i].sh_type != SHT_SYMTAB)
			continue;

		info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
		info->symtab_stop  = (void *)hdr + sechdrs[i].sh_offset 
			                         + sechdrs[i].sh_size;
		info->strtab       = (void *)hdr + 
			             sechdrs[sechdrs[i].sh_link].sh_offset;
	}
	if (!info->symtab_start) {
		fprintf(stderr, "modpost: %s no symtab?\n", filename);
		abort();
	}
	/* Fix endianness in symbols */
	for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
		sym->st_shndx = TO_NATIVE(sym->st_shndx);
		sym->st_name  = TO_NATIVE(sym->st_name);
		sym->st_value = TO_NATIVE(sym->st_value);
		sym->st_size  = TO_NATIVE(sym->st_size);
	}
	return;

 truncated:
	fprintf(stderr, "modpost: %s is truncated.\n", filename);
	abort();
}

void
parse_elf_finish(struct elf_info *info)
{
	release_file(info->hdr, info->size);
}

#define CRC_PFX     MODULE_SYMBOL_PREFIX "__crc_"
#define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__ksymtab_"

void
handle_modversions(struct module *mod, struct elf_info *info,
		   Elf_Sym *sym, const char *symname)
{
	unsigned int crc;

	switch (sym->st_shndx) {
	case SHN_COMMON:
		fprintf(stderr, "*** Warning: \"%s\" [%s] is COMMON symbol\n",
			symname, mod->name);
		break;
	case SHN_ABS:
		/* CRC'd symbol */
		if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
			crc = (unsigned int) sym->st_value;
			add_exported_symbol(symname + strlen(CRC_PFX),
					    mod, &crc);
		}
		break;
	case SHN_UNDEF:
		/* undefined symbol */
		if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL)
			break;
		/* ignore global offset table */
		if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
			break;
		/* ignore __this_module, it will be resolved shortly */
		if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
			break;
#ifdef STT_REGISTER
		if (info->hdr->e_machine == EM_SPARC ||
		    info->hdr->e_machine == EM_SPARCV9) {
			/* Ignore register directives. */
			if (ELF_ST_TYPE(sym->st_info) == STT_REGISTER)
				break;
		}
#endif
		
		if (memcmp(symname, MODULE_SYMBOL_PREFIX,
			   strlen(MODULE_SYMBOL_PREFIX)) == 0)
			mod->unres = alloc_symbol(symname +