linux/kernel/kallsyms.c
Franck Bui-Huu ffc5089196 [PATCH] Create kallsyms_lookup_size_offset()
Some uses of kallsyms_lookup() do not need to find out the name of a symbol
and its module's name it belongs.  This is specially true in arch specific
code, which needs to unwind the stack to show the back trace during oops
(mips is an example).  In this specific case, we just need to retreive the
function's size and the offset of the active intruction inside it.

Adds a new entry "kallsyms_lookup_size_offset()" This new entry does
exactly the same as kallsyms_lookup() but does not require any buffers to
store any names.

It returns 0 if it fails otherwise 1.

Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-03 08:03:41 -07:00

458 lines
11 KiB
C

/*
* 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 <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 unsigned long kallsyms_addresses[] __attribute__((weak));
extern unsigned long kallsyms_num_syms __attribute__((weak,section("data")));
extern u8 kallsyms_names[] __attribute__((weak));
extern u8 kallsyms_token_table[] __attribute__((weak));
extern u16 kallsyms_token_index[] __attribute__((weak));
extern 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;
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)
{
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];
};
/* Only label it "global" if it is exported. */
static void upcase_if_global(struct kallsym_iter *iter)
{
if (is_exported(iter->name, iter->owner))
iter->type += 'A' - 'a';
}
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;
upcase_if_global(iter);
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 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 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);