/*
* 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+1];
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;
}
*symbolsize = symbol_end - symbol_start;
*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] = 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);
*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);
return NULL;
}
/* Replace "%s" in format with address, or returns -errno. */
void __print_symbol(const char *fmt, unsigned long address)
{
char *modname;
const char *name;
unsigned long offset, size;
char namebuf[KSYM_NAME_LEN+1];
char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +
2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1];
name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
if (!name)
sprintf(buffer, "0x%lx", address);
else {
if (modname)
sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
size, modname);
else
sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
}
printk(fmt, buffer);
}
/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
struct kallsym_iter
{
loff_t pos;
struct module *owner;
unsigned long value;
unsigned int nameoff; /* If iterating in core kernel symbols */
char type;
char name[KSYM_NAME_LEN+1];
};
static int get_ksymbol_mod(struct kallsym_iter *iter)
{
iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
&iter->value, &iter->type,
iter->name, sizeof(iter->name));
if (iter->owner == NULL)
return 0;
/* Label it "global" if it is exported, "local" if not exported. */
iter->type = is_exported(iter->name, iter->owner)
? toupper(iter->type) : tolower(iter->type);
return 1;
}
/* Returns space to next name. */
static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
{
unsigned off = iter->nameoff;
iter->owner = NULL;
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->owner)
seq_printf(m, "%0*lx %c %s\t[%s]\n",
(int)(2*sizeof(void*)),
iter->value, iter->type, iter->name,
module_name(iter->owner));
else
seq_printf(m, "%0*lx %c %s\n",
(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 int kallsyms_release(struct inode *inode, struct file *file)
{
struct seq_file *m = (struct seq_file *)file->private_data;
kfree(m->private);
return seq_release(inode, file);
}
static const struct file_operations kallsyms_operations = {
.open = kallsyms_open,
.read = seq_read,
.llseek = seq_lseek,
.release = kallsyms_release,
};
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);
