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/* -*- linux-c -*-
* Symbolic Lookup Functions
* Copyright (C) 2005-2008 Red Hat Inc.
* Copyright (C) 2006 Intel Corporation.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _STP_SYM_C_
#define _STP_SYM_C_
#include "string.c"
/** @file sym.c
* @addtogroup sym Symbolic Functions
* Symbolic Lookup Functions
* @{
*/
/* XXX: this needs to be address-space-specific. */
unsigned long _stp_module_relocate(const char *module, const char *section, unsigned long offset)
{
static struct _stp_module *last = NULL;
static struct _stp_section *last_sec;
unsigned long flags;
unsigned i, j;
/* if module is -1, we invalidate last. _stp_del_module calls this when modules are deleted. */
if ((long)module == -1) {
last = NULL;
return 0;
}
dbug_sym(1, "%s, %s, %lx\n", module, section, offset);
if (!module || !strcmp(section, "") /* absolute, unrelocated address */
||_stp_num_modules == 0) {
return offset;
}
/* Most likely our relocation is in the same section of the same module as the last. */
if (last) {
if (!strcmp(module, last->name) && !strcmp(section, last_sec->name)) {
offset += last_sec->addr;
dbug_sym(1, "cached address=%lx\n", offset);
return offset;
}
}
for (i = 0; i < _stp_num_modules; i++) {
last = _stp_modules[i];
if (strcmp(module, last->name))
continue;
for (j = 0; j < last->num_sections; j++) {
last_sec = &last->sections[j];
if (!strcmp(section, last_sec->name)) {
if (last_sec->addr == 0) /* module/section not in memory */
continue;
offset += last_sec->addr;
dbug_sym(1, "address=%lx\n", offset);
return offset;
}
}
}
last = NULL;
return 0;
}
/* Return module owner and fills in closest section of the address
if found, return NULL otherwise.
XXX: needs to be address-space-specific. */
static struct _stp_module *_stp_mod_sec_lookup(unsigned long addr,
struct _stp_section **sec)
{
struct _stp_module *m = NULL;
unsigned midx = 0;
unsigned long closest_section_offset = ~0;
for (midx = 0; midx < _stp_num_modules; midx++)
{
unsigned secidx;
for (secidx = 0; secidx < _stp_modules[midx]->num_sections; secidx++)
{
unsigned long this_section_addr;
unsigned long this_section_offset;
this_section_addr = _stp_modules[midx]->sections[secidx].addr;
if (addr < this_section_addr) continue;
this_section_offset = addr - this_section_addr;
if (this_section_offset < closest_section_offset)
{
closest_section_offset = this_section_offset;
m = _stp_modules[midx];
*sec = & m->sections[secidx];
}
}
}
return m;
}
/* XXX: needs to be address-space-specific. */
static const char *_stp_kallsyms_lookup(unsigned long addr, unsigned long *symbolsize,
unsigned long *offset,
const char **modname,
/* char ** secname? */
char *namebuf)
{
struct _stp_module *m = NULL;
struct _stp_section *sec = NULL;
struct _stp_symbol *s = NULL;
unsigned long flags;
unsigned end, begin = 0;
m = _stp_mod_sec_lookup(addr, &sec);
if (unlikely (m == NULL || sec == NULL))
return NULL;
/* NB: relativize the address to the section. */
addr -= sec->addr;
end = sec->num_symbols;
/* binary search for symbols within the module */
do {
unsigned mid = (begin + end) / 2;
if (addr < sec->symbols[mid].addr)
end = mid;
else
begin = mid;
} while (begin + 1 < end);
/* result index in $begin */
s = & sec->symbols[begin];
if (likely(addr >= s->addr)) {
if (offset)
*offset = addr - s->addr;
if (modname)
*modname = m->name;
/* We could also pass sec->name here. */
if (symbolsize) {
if ((begin + 1) < sec->num_symbols)
*symbolsize = sec->symbols[begin + 1].addr - s->addr;
else
*symbolsize = 0;
// NB: This is only a heuristic. Sometimes there are large
// gaps between text areas of modules.
}
if (namebuf) {
strlcpy(namebuf, s->symbol, KSYM_NAME_LEN + 1);
return namebuf;
} else {
return s->symbol;
}
}
return NULL;
}
/* Validate module/kernel based on build-id if there
* The completed case is the following combination:
* Debuginfo Module Kernel
* X X
* has build-id/not unloaded has build-id/not
* loaded && (has build-id/not)
*
* NB: build-id exists only if ld>=2.18 and kernel>= 2.6.23
*/
static int _stp_module_check(void)
{
struct _stp_module *m = NULL;
unsigned long notes_addr, base_addr;
unsigned i,j;
for (i = 0; i < _stp_num_modules; i++)
{
m = _stp_modules[i];
if (m->build_id_len > 0 && m->notes_sect != 0) {
dbug_sym(1, "build-id validation [%s]\n", m->name);
/* notes end address */
if (!strcmp(m->name, "kernel")) {
notes_addr = m->build_id_offset;
base_addr = _stp_module_relocate("kernel",
"_stext", 0);
} else {
notes_addr = m->notes_sect + m->build_id_offset;
base_addr = m->notes_sect;
}
/* build-id note payload start address */
/* XXX: But see https://bugzilla.redhat.com/show_bug.cgi?id=465872;
dwfl_module_build_id was not intended to return the end address. */
notes_addr -= m->build_id_len;
if (notes_addr > base_addr) {
for (j = 0; j < m->build_id_len; j++)
{
unsigned char theory, practice;
theory = m->build_id_bits [j];
practice = ((unsigned char*) notes_addr) [j];
/* XXX: consider using kread() instead of above. */
if (theory != practice)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,27)
_stp_error ("%s: inconsistent %s build-id byte #%d "
"(0x%x [actual] vs. 0x%x [debuginfo])\n",
THIS_MODULE->name, m->name, j,
practice, theory);
return 1;
#else
/* This branch is a surrogate for
kernels affected by Fedora bug
#465873. */
printk(KERN_WARNING
"%s: inconsistent %s build-id byte #%d "
"(0x%x [actual] vs. 0x%x [debuginfo])\n",
THIS_MODULE->name, m->name, j,
practice, theory);
break; /* Note just the first mismatch. */
#endif
}
}
}
} /* end checking */
} /* end loop */
return 0;
}
/** Print an address symbolically.
* @param address The address to lookup.
* @note Symbolic lookups should not normally be done within
* a probe because it is too time-consuming. Use at module exit time.
*/
void _stp_symbol_print(unsigned long address)
{
const char *modname;
const char *name;
unsigned long offset, size;
name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL);
_stp_printf("%p", (int64_t) address);
if (name) {
if (modname && *modname)
_stp_printf(" : %s+%#lx/%#lx [%s]", name, offset, size, modname);
else
_stp_printf(" : %s+%#lx/%#lx", name, offset, size);
}
}
/* Like _stp_symbol_print, except only print if the address is a valid function address */
int _stp_func_print(unsigned long address, int verbose, int exact)
{
const char *modname;
const char *name;
unsigned long offset, size;
char *exstr;
if (exact)
exstr = "";
else
exstr = " (inexact)";
name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL);
if (name) {
if (verbose) {
if (modname && *modname)
_stp_printf(" %p : %s+%#lx/%#lx [%s]%s\n",
(int64_t) address, name, offset, size, modname, exstr);
else
_stp_printf(" %p : %s+%#lx/%#lx%s\n", (int64_t) address, name, offset, size, exstr);
} else
_stp_printf("%p ", (int64_t) address);
return 1;
}
return 0;
}
void _stp_symbol_snprint(char *str, size_t len, unsigned long address)
{
const char *modname;
const char *name;
unsigned long offset, size;
name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL);
if (name)
strlcpy(str, name, len);
else
_stp_snprintf(str, len, "%p", (int64_t) address);
}
/** @} */
#endif /* _STP_SYM_C_ */
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