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411 lines
10 KiB
411 lines
10 KiB
/*
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* kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
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*
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* Rewritten and vastly simplified by Rusty Russell for in-kernel
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* module loader:
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* Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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*
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* ChangeLog:
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*
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* (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
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* Changed the compression method from stem compression to "table lookup"
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* compression (see scripts/kallsyms.c for a more complete description)
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*/
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#include <linux/kallsyms.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/seq_file.h>
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#include <linux/fs.h>
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#include <linux/err.h>
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#include <linux/proc_fs.h>
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#include <linux/mm.h>
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#include <asm/sections.h>
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#ifdef CONFIG_KALLSYMS_ALL
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#define all_var 1
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#else
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#define all_var 0
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#endif
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/* These will be re-linked against their real values during the second link stage */
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extern unsigned long kallsyms_addresses[] __attribute__((weak));
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extern unsigned long kallsyms_num_syms __attribute__((weak,section("data")));
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extern u8 kallsyms_names[] __attribute__((weak));
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extern u8 kallsyms_token_table[] __attribute__((weak));
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extern u16 kallsyms_token_index[] __attribute__((weak));
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extern unsigned long kallsyms_markers[] __attribute__((weak));
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static inline int is_kernel_inittext(unsigned long addr)
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{
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if (addr >= (unsigned long)_sinittext
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&& addr <= (unsigned long)_einittext)
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return 1;
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return 0;
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}
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static inline int is_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
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return 1;
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return in_gate_area_no_task(addr);
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}
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static inline int is_kernel(unsigned long addr)
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{
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if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
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return 1;
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return in_gate_area_no_task(addr);
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}
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/* expand a compressed symbol data into the resulting uncompressed string,
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given the offset to where the symbol is in the compressed stream */
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static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
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{
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int len, skipped_first = 0;
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u8 *tptr, *data;
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/* get the compressed symbol length from the first symbol byte */
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data = &kallsyms_names[off];
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len = *data;
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data++;
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/* update the offset to return the offset for the next symbol on
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* the compressed stream */
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off += len + 1;
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/* for every byte on the compressed symbol data, copy the table
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entry for that byte */
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while(len) {
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tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ];
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data++;
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len--;
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while (*tptr) {
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if(skipped_first) {
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*result = *tptr;
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result++;
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} else
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skipped_first = 1;
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tptr++;
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}
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}
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*result = '\0';
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/* return to offset to the next symbol */
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return off;
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}
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/* get symbol type information. This is encoded as a single char at the
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* begining of the symbol name */
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static char kallsyms_get_symbol_type(unsigned int off)
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{
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/* get just the first code, look it up in the token table, and return the
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* first char from this token */
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return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ];
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}
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/* find the offset on the compressed stream given and index in the
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* kallsyms array */
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static unsigned int get_symbol_offset(unsigned long pos)
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{
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u8 *name;
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int i;
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/* use the closest marker we have. We have markers every 256 positions,
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* so that should be close enough */
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name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
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/* sequentially scan all the symbols up to the point we're searching for.
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* Every symbol is stored in a [<len>][<len> bytes of data] format, so we
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* just need to add the len to the current pointer for every symbol we
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* wish to skip */
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for(i = 0; i < (pos&0xFF); i++)
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name = name + (*name) + 1;
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return name - kallsyms_names;
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}
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/* Lookup the address for this symbol. Returns 0 if not found. */
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unsigned long kallsyms_lookup_name(const char *name)
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{
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char namebuf[KSYM_NAME_LEN+1];
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unsigned long i;
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unsigned int off;
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for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
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off = kallsyms_expand_symbol(off, namebuf);
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if (strcmp(namebuf, name) == 0)
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return kallsyms_addresses[i];
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}
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return module_kallsyms_lookup_name(name);
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}
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EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
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/*
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* Lookup an address
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* - modname is set to NULL if it's in the kernel
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* - we guarantee that the returned name is valid until we reschedule even if
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* it resides in a module
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* - we also guarantee that modname will be valid until rescheduled
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*/
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const char *kallsyms_lookup(unsigned long addr,
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unsigned long *symbolsize,
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unsigned long *offset,
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char **modname, char *namebuf)
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{
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unsigned long i, low, high, mid;
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const char *msym;
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/* This kernel should never had been booted. */
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BUG_ON(!kallsyms_addresses);
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namebuf[KSYM_NAME_LEN] = 0;
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namebuf[0] = 0;
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if ((all_var && is_kernel(addr)) ||
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(!all_var && (is_kernel_text(addr) || is_kernel_inittext(addr)))) {
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unsigned long symbol_end=0;
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/* do a binary search on the sorted kallsyms_addresses array */
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low = 0;
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high = kallsyms_num_syms;
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while (high-low > 1) {
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mid = (low + high) / 2;
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if (kallsyms_addresses[mid] <= addr) low = mid;
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else high = mid;
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}
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/* search for the first aliased symbol. Aliased symbols are
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symbols with the same address */
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while (low && kallsyms_addresses[low - 1] == kallsyms_addresses[low])
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--low;
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/* Grab name */
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kallsyms_expand_symbol(get_symbol_offset(low), namebuf);
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/* Search for next non-aliased symbol */
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for (i = low + 1; i < kallsyms_num_syms; i++) {
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if (kallsyms_addresses[i] > kallsyms_addresses[low]) {
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symbol_end = kallsyms_addresses[i];
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break;
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}
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}
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/* if we found no next symbol, we use the end of the section */
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if (!symbol_end) {
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if (is_kernel_inittext(addr))
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symbol_end = (unsigned long)_einittext;
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else
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symbol_end = all_var ? (unsigned long)_end : (unsigned long)_etext;
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}
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*symbolsize = symbol_end - kallsyms_addresses[low];
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*modname = NULL;
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*offset = addr - kallsyms_addresses[low];
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return namebuf;
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}
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/* see if it's in a module */
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msym = module_address_lookup(addr, symbolsize, offset, modname);
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if (msym)
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return strncpy(namebuf, msym, KSYM_NAME_LEN);
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return NULL;
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}
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/* Replace "%s" in format with address, or returns -errno. */
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void __print_symbol(const char *fmt, unsigned long address)
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{
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char *modname;
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const char *name;
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unsigned long offset, size;
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char namebuf[KSYM_NAME_LEN+1];
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char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +
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2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1];
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name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
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if (!name)
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sprintf(buffer, "0x%lx", address);
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else {
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if (modname)
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sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
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size, modname);
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else
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sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
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}
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printk(fmt, buffer);
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}
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/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
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struct kallsym_iter
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{
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loff_t pos;
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struct module *owner;
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unsigned long value;
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unsigned int nameoff; /* If iterating in core kernel symbols */
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char type;
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char name[KSYM_NAME_LEN+1];
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};
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/* Only label it "global" if it is exported. */
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static void upcase_if_global(struct kallsym_iter *iter)
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{
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if (is_exported(iter->name, iter->owner))
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iter->type += 'A' - 'a';
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}
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static int get_ksymbol_mod(struct kallsym_iter *iter)
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{
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iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
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&iter->value,
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&iter->type, iter->name);
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if (iter->owner == NULL)
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return 0;
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upcase_if_global(iter);
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return 1;
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}
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/* Returns space to next name. */
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static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
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{
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unsigned off = iter->nameoff;
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iter->owner = NULL;
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iter->value = kallsyms_addresses[iter->pos];
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iter->type = kallsyms_get_symbol_type(off);
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off = kallsyms_expand_symbol(off, iter->name);
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return off - iter->nameoff;
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}
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static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
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{
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iter->name[0] = '\0';
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iter->nameoff = get_symbol_offset(new_pos);
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iter->pos = new_pos;
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}
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/* Returns false if pos at or past end of file. */
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static int update_iter(struct kallsym_iter *iter, loff_t pos)
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{
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/* Module symbols can be accessed randomly. */
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if (pos >= kallsyms_num_syms) {
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iter->pos = pos;
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return get_ksymbol_mod(iter);
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}
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/* If we're not on the desired position, reset to new position. */
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if (pos != iter->pos)
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reset_iter(iter, pos);
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iter->nameoff += get_ksymbol_core(iter);
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iter->pos++;
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return 1;
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}
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static void *s_next(struct seq_file *m, void *p, loff_t *pos)
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{
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(*pos)++;
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if (!update_iter(m->private, *pos))
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return NULL;
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return p;
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}
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static void *s_start(struct seq_file *m, loff_t *pos)
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{
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if (!update_iter(m->private, *pos))
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return NULL;
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return m->private;
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}
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static void s_stop(struct seq_file *m, void *p)
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{
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}
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static int s_show(struct seq_file *m, void *p)
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{
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struct kallsym_iter *iter = m->private;
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/* Some debugging symbols have no name. Ignore them. */
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if (!iter->name[0])
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return 0;
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if (iter->owner)
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seq_printf(m, "%0*lx %c %s\t[%s]\n",
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(int)(2*sizeof(void*)),
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iter->value, iter->type, iter->name,
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module_name(iter->owner));
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else
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seq_printf(m, "%0*lx %c %s\n",
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(int)(2*sizeof(void*)),
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iter->value, iter->type, iter->name);
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return 0;
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}
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static struct seq_operations kallsyms_op = {
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.start = s_start,
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.next = s_next,
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.stop = s_stop,
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.show = s_show
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};
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static int kallsyms_open(struct inode *inode, struct file *file)
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{
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/* We keep iterator in m->private, since normal case is to
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* s_start from where we left off, so we avoid doing
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* using get_symbol_offset for every symbol */
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struct kallsym_iter *iter;
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int ret;
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iter = kmalloc(sizeof(*iter), GFP_KERNEL);
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if (!iter)
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return -ENOMEM;
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reset_iter(iter, 0);
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ret = seq_open(file, &kallsyms_op);
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if (ret == 0)
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((struct seq_file *)file->private_data)->private = iter;
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else
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kfree(iter);
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return ret;
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}
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static int kallsyms_release(struct inode *inode, struct file *file)
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{
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struct seq_file *m = (struct seq_file *)file->private_data;
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kfree(m->private);
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return seq_release(inode, file);
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}
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static struct file_operations kallsyms_operations = {
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.open = kallsyms_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = kallsyms_release,
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};
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static int __init kallsyms_init(void)
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{
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struct proc_dir_entry *entry;
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entry = create_proc_entry("kallsyms", 0444, NULL);
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if (entry)
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entry->proc_fops = &kallsyms_operations;
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return 0;
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}
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__initcall(kallsyms_init);
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EXPORT_SYMBOL(__print_symbol);
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