/*
   * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
   *
   * Rewritten and vastly simplified by Rusty Russell for in-kernel
   * module loader:
   *   Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
   *
   * ChangeLog:
   *
   * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
   *      Changed the compression method from stem compression to "table lookup"
   *      compression (see scripts/kallsyms.c for a more complete description)
   */
  #include <linux/kallsyms.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/seq_file.h>
  #include <linux/fs.h>
  #include <linux/err.h>
  #include <linux/proc_fs.h>

  #include <linux/sched.h>	/* for cond_resched */

  #include <linux/mm.h>

  #include <linux/ctype.h>

  
  #include <asm/sections.h>
  
  #ifdef CONFIG_KALLSYMS_ALL
  #define all_var 1
  #else
  #define all_var 0
  #endif
  
  /* These will be re-linked against their real values during the second link stage */

  extern const unsigned long kallsyms_addresses[] __attribute__((weak));
  extern const unsigned long kallsyms_num_syms __attribute__((weak));
  extern const u8 kallsyms_names[] __attribute__((weak));

  extern const u8 kallsyms_token_table[] __attribute__((weak));
  extern const u16 kallsyms_token_index[] __attribute__((weak));

  extern const unsigned long kallsyms_markers[] __attribute__((weak));

  
  static inline int is_kernel_inittext(unsigned long addr)
  {
  	if (addr >= (unsigned long)_sinittext
  	    && addr <= (unsigned long)_einittext)
  		return 1;
  	return 0;
  }

  static inline int is_kernel_extratext(unsigned long addr)
  {
  	if (addr >= (unsigned long)_sextratext
  	    && addr <= (unsigned long)_eextratext)
  		return 1;
  	return 0;
  }

  static inline int is_kernel_text(unsigned long addr)
  {
  	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
  		return 1;
  	return in_gate_area_no_task(addr);
  }
  
  static inline int is_kernel(unsigned long addr)
  {
  	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
  		return 1;
  	return in_gate_area_no_task(addr);
  }

  static int is_ksym_addr(unsigned long addr)
  {
  	if (all_var)
  		return is_kernel(addr);
  
  	return is_kernel_text(addr) || is_kernel_inittext(addr) ||
  		is_kernel_extratext(addr);
  }

  /* expand a compressed symbol data into the resulting uncompressed string,
     given the offset to where the symbol is in the compressed stream */
  static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
  {
  	int len, skipped_first = 0;

  	const u8 *tptr, *data;

  
  	/* get the compressed symbol length from the first symbol byte */
  	data = &kallsyms_names[off];
  	len = *data;
  	data++;
  
  	/* update the offset to return the offset for the next symbol on
  	 * the compressed stream */
  	off += len + 1;
  
  	/* for every byte on the compressed symbol data, copy the table
  	   entry for that byte */
  	while(len) {
  		tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ];
  		data++;
  		len--;
  
  		while (*tptr) {
  			if(skipped_first) {
  				*result = *tptr;
  				result++;
  			} else
  				skipped_first = 1;
  			tptr++;
  		}
  	}
  
  	*result = '\0';
  
  	/* return to offset to the next symbol */
  	return off;
  }
  
  /* get symbol type information. This is encoded as a single char at the
   * begining of the symbol name */
  static char kallsyms_get_symbol_type(unsigned int off)
  {
  	/* get just the first code, look it up in the token table, and return the
  	 * first char from this token */
  	return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ];
  }
  
  
  /* find the offset on the compressed stream given and index in the
   * kallsyms array */
  static unsigned int get_symbol_offset(unsigned long pos)
  {

  	const u8 *name;

  	int i;
  
  	/* use the closest marker we have. We have markers every 256 positions,
  	 * so that should be close enough */
  	name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
  
  	/* sequentially scan all the symbols up to the point we're searching for.
  	 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
  	 * just need to add the len to the current pointer for every symbol we
  	 * wish to skip */
  	for(i = 0; i < (pos&0xFF); i++)
  		name = name + (*name) + 1;
  
  	return name - kallsyms_names;
  }
  
  /* Lookup the address for this symbol. Returns 0 if not found. */
  unsigned long kallsyms_lookup_name(const char *name)
  {

  	char namebuf[KSYM_NAME_LEN];

  	unsigned long i;
  	unsigned int off;
  
  	for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
  		off = kallsyms_expand_symbol(off, namebuf);
  
  		if (strcmp(namebuf, name) == 0)
  			return kallsyms_addresses[i];
  	}
  	return module_kallsyms_lookup_name(name);
  }

  static unsigned long get_symbol_pos(unsigned long addr,
  				    unsigned long *symbolsize,
  				    unsigned long *offset)
  {
  	unsigned long symbol_start = 0, symbol_end = 0;
  	unsigned long i, low, high, mid;
  
  	/* This kernel should never had been booted. */
  	BUG_ON(!kallsyms_addresses);
  
  	/* do a binary search on the sorted kallsyms_addresses array */
  	low = 0;
  	high = kallsyms_num_syms;
  
  	while (high - low > 1) {
  		mid = (low + high) / 2;
  		if (kallsyms_addresses[mid] <= addr)
  			low = mid;
  		else
  			high = mid;
  	}
  
  	/*
  	 * search for the first aliased symbol. Aliased
  	 * symbols are symbols with the same address
  	 */
  	while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
  		--low;
  
  	symbol_start = kallsyms_addresses[low];
  
  	/* Search for next non-aliased symbol */
  	for (i = low + 1; i < kallsyms_num_syms; i++) {
  		if (kallsyms_addresses[i] > symbol_start) {
  			symbol_end = kallsyms_addresses[i];
  			break;
  		}
  	}
  
  	/* if we found no next symbol, we use the end of the section */
  	if (!symbol_end) {
  		if (is_kernel_inittext(addr))
  			symbol_end = (unsigned long)_einittext;
  		else if (all_var)
  			symbol_end = (unsigned long)_end;
  		else
  			symbol_end = (unsigned long)_etext;
  	}

  	if (symbolsize)
  		*symbolsize = symbol_end - symbol_start;
  	if (offset)
  		*offset = addr - symbol_start;

  
  	return low;
  }
  
  /*
   * Lookup an address but don't bother to find any names.
   */
  int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
  				unsigned long *offset)
  {
  	if (is_ksym_addr(addr))
  		return !!get_symbol_pos(addr, symbolsize, offset);
  
  	return !!module_address_lookup(addr, symbolsize, offset, NULL);
  }

  /*
   * Lookup an address
   * - modname is set to NULL if it's in the kernel
   * - we guarantee that the returned name is valid until we reschedule even if
   *   it resides in a module
   * - we also guarantee that modname will be valid until rescheduled
   */
  const char *kallsyms_lookup(unsigned long addr,
  			    unsigned long *symbolsize,
  			    unsigned long *offset,
  			    char **modname, char *namebuf)
  {

  	const char *msym;

  	namebuf[KSYM_NAME_LEN - 1] = 0;

  	namebuf[0] = 0;

  	if (is_ksym_addr(addr)) {
  		unsigned long pos;

  		pos = get_symbol_pos(addr, symbolsize, offset);

  		/* Grab name */

  		kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);

  		if (modname)
  			*modname = NULL;

  		return namebuf;
  	}
  
  	/* see if it's in a module */
  	msym = module_address_lookup(addr, symbolsize, offset, modname);
  	if (msym)

  		return strncpy(namebuf, msym, KSYM_NAME_LEN - 1);

  
  	return NULL;
  }

  int lookup_symbol_name(unsigned long addr, char *symname)
  {
  	symname[0] = '\0';

  	symname[KSYM_NAME_LEN - 1] = '\0';

  
  	if (is_ksym_addr(addr)) {
  		unsigned long pos;
  
  		pos = get_symbol_pos(addr, NULL, NULL);
  		/* Grab name */
  		kallsyms_expand_symbol(get_symbol_offset(pos), symname);
  		return 0;
  	}
  	/* see if it's in a module */
  	return lookup_module_symbol_name(addr, symname);
  }

  int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
  			unsigned long *offset, char *modname, char *name)
  {
  	name[0] = '\0';

  	name[KSYM_NAME_LEN - 1] = '\0';

  
  	if (is_ksym_addr(addr)) {
  		unsigned long pos;
  
  		pos = get_symbol_pos(addr, size, offset);
  		/* Grab name */
  		kallsyms_expand_symbol(get_symbol_offset(pos), name);
  		modname[0] = '\0';
  		return 0;
  	}
  	/* see if it's in a module */
  	return lookup_module_symbol_attrs(addr, size, offset, modname, name);
  }

  /* Look up a kernel symbol and return it in a text buffer. */
  int sprint_symbol(char *buffer, unsigned long address)

  {
  	char *modname;
  	const char *name;
  	unsigned long offset, size;

  	char namebuf[KSYM_NAME_LEN];

  
  	name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);

  	if (!name)

  		return sprintf(buffer, "0x%lx", address);

  
  	if (modname)
  		return sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,

  				size, modname);

  	else
  		return sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);

  }
  
  /* Look up a kernel symbol and print it to the kernel messages. */
  void __print_symbol(const char *fmt, unsigned long address)
  {
  	char buffer[KSYM_SYMBOL_LEN];
  
  	sprint_symbol(buffer, address);

  	printk(fmt, buffer);
  }
  
  /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
  struct kallsym_iter
  {
  	loff_t pos;

  	unsigned long value;
  	unsigned int nameoff; /* If iterating in core kernel symbols */
  	char type;

  	char name[KSYM_NAME_LEN];
  	char module_name[MODULE_NAME_LEN];

  	int exported;

  };

  static int get_ksymbol_mod(struct kallsym_iter *iter)
  {

  	if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
  				&iter->type, iter->name, iter->module_name,
  				&iter->exported) < 0)

  		return 0;

  	return 1;
  }
  
  /* Returns space to next name. */
  static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
  {
  	unsigned off = iter->nameoff;

  	iter->module_name[0] = '\0';

  	iter->value = kallsyms_addresses[iter->pos];
  
  	iter->type = kallsyms_get_symbol_type(off);
  
  	off = kallsyms_expand_symbol(off, iter->name);
  
  	return off - iter->nameoff;
  }
  
  static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
  {
  	iter->name[0] = '\0';
  	iter->nameoff = get_symbol_offset(new_pos);
  	iter->pos = new_pos;
  }
  
  /* Returns false if pos at or past end of file. */
  static int update_iter(struct kallsym_iter *iter, loff_t pos)
  {
  	/* Module symbols can be accessed randomly. */
  	if (pos >= kallsyms_num_syms) {
  		iter->pos = pos;
  		return get_ksymbol_mod(iter);
  	}
  	
  	/* If we're not on the desired position, reset to new position. */
  	if (pos != iter->pos)
  		reset_iter(iter, pos);
  
  	iter->nameoff += get_ksymbol_core(iter);
  	iter->pos++;
  
  	return 1;
  }
  
  static void *s_next(struct seq_file *m, void *p, loff_t *pos)
  {
  	(*pos)++;
  
  	if (!update_iter(m->private, *pos))
  		return NULL;
  	return p;
  }
  
  static void *s_start(struct seq_file *m, loff_t *pos)
  {
  	if (!update_iter(m->private, *pos))
  		return NULL;
  	return m->private;
  }
  
  static void s_stop(struct seq_file *m, void *p)
  {
  }
  
  static int s_show(struct seq_file *m, void *p)
  {
  	struct kallsym_iter *iter = m->private;
  
  	/* Some debugging symbols have no name.  Ignore them. */ 
  	if (!iter->name[0])
  		return 0;

  	if (iter->module_name[0]) {
  		char type;
  
  		/* Label it "global" if it is exported,
  		 * "local" if not exported. */
  		type = iter->exported ? toupper(iter->type) :
  					tolower(iter->type);

  		seq_printf(m, "%0*lx %c %s\t[%s]
  ",
  			   (int)(2*sizeof(void*)),

  			   iter->value, type, iter->name, iter->module_name);
  	} else

  		seq_printf(m, "%0*lx %c %s
  ",
  			   (int)(2*sizeof(void*)),
  			   iter->value, iter->type, iter->name);
  	return 0;
  }

  static const struct seq_operations kallsyms_op = {

  	.start = s_start,
  	.next = s_next,
  	.stop = s_stop,
  	.show = s_show
  };
  
  static int kallsyms_open(struct inode *inode, struct file *file)
  {
  	/* We keep iterator in m->private, since normal case is to
  	 * s_start from where we left off, so we avoid doing
  	 * using get_symbol_offset for every symbol */
  	struct kallsym_iter *iter;
  	int ret;
  
  	iter = kmalloc(sizeof(*iter), GFP_KERNEL);
  	if (!iter)
  		return -ENOMEM;
  	reset_iter(iter, 0);
  
  	ret = seq_open(file, &kallsyms_op);
  	if (ret == 0)
  		((struct seq_file *)file->private_data)->private = iter;
  	else
  		kfree(iter);
  	return ret;
  }

  static const struct file_operations kallsyms_operations = {

  	.open = kallsyms_open,
  	.read = seq_read,
  	.llseek = seq_lseek,

  	.release = seq_release_private,

  };
  
  static int __init kallsyms_init(void)
  {
  	struct proc_dir_entry *entry;
  
  	entry = create_proc_entry("kallsyms", 0444, NULL);
  	if (entry)
  		entry->proc_fops = &kallsyms_operations;
  	return 0;
  }
  __initcall(kallsyms_init);
  
  EXPORT_SYMBOL(__print_symbol);

  EXPORT_SYMBOL_GPL(sprint_symbol);