freebsd-skq/sys/kern/subr_stack.c
avg 9864877541 kdb_backtrace: use stack_print_ddb instead of stack_print
This is a followup to r212964.
stack_print call chain obtains linker sx lock and thus potentially may
lead to a deadlock depending on a kind of a panic.
stack_print_ddb doesn't acquire any locks and it doesn't use any
facilities of ddb backend.
Using stack_print_ddb outside of DDB ifdef required taking a number of
helper functions from under it as well.

It is a good idea to rename linker_ddb_* and stack_*_ddb functions to
have 'unlocked' component in their name instead of 'ddb', because those
functions do not use any DDB services, but instead they provide unlocked
access to linker symbol information.  The latter was previously needed
only for DDB, hence the 'ddb' name component.

Alternative is to ditch unlocked versions altogether after implementing
proper panic handling:
1. stop other cpus upon a panic
2. make all non-spinlock lock operations (mutex, sx, rwlock) be a no-op
   when panicstr != NULL

Suggested by:	mdf
Discussed with:	attilio
MFC after:	2 weeks
2010-09-22 06:45:07 +00:00

275 lines
6.2 KiB
C

/*-
* Copyright (c) 2005 Antoine Brodin
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "opt_ddb.h"
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#ifdef KTR
#include <sys/ktr.h>
#endif
#include <sys/linker.h>
#include <sys/malloc.h>
#include <sys/sbuf.h>
#include <sys/stack.h>
#include <sys/systm.h>
static MALLOC_DEFINE(M_STACK, "stack", "Stack Traces");
static int stack_symbol(vm_offset_t pc, char *namebuf, u_int buflen,
long *offset);
static int stack_symbol_ddb(vm_offset_t pc, const char **name, long *offset);
struct stack *
stack_create(void)
{
struct stack *st;
st = malloc(sizeof *st, M_STACK, M_WAITOK | M_ZERO);
return (st);
}
void
stack_destroy(struct stack *st)
{
free(st, M_STACK);
}
int
stack_put(struct stack *st, vm_offset_t pc)
{
if (st->depth < STACK_MAX) {
st->pcs[st->depth++] = pc;
return (0);
} else
return (-1);
}
void
stack_copy(struct stack *src, struct stack *dst)
{
*dst = *src;
}
void
stack_zero(struct stack *st)
{
bzero(st, sizeof *st);
}
void
stack_print(struct stack *st)
{
char namebuf[64];
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
(void)stack_symbol(st->pcs[i], namebuf, sizeof(namebuf),
&offset);
printf("#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
namebuf, offset);
}
}
void
stack_print_short(struct stack *st)
{
char namebuf[64];
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
if (i > 0)
printf(" ");
if (stack_symbol(st->pcs[i], namebuf, sizeof(namebuf),
&offset) == 0)
printf("%s+%#lx", namebuf, offset);
else
printf("%p", (void *)st->pcs[i]);
}
printf("\n");
}
void
stack_print_ddb(struct stack *st)
{
const char *name;
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
stack_symbol_ddb(st->pcs[i], &name, &offset);
printf("#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
name, offset);
}
}
#ifdef DDB
void
stack_print_short_ddb(struct stack *st)
{
const char *name;
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
if (i > 0)
printf(" ");
if (stack_symbol_ddb(st->pcs[i], &name, &offset) == 0)
printf("%s+%#lx", name, offset);
else
printf("%p", (void *)st->pcs[i]);
}
printf("\n");
}
#endif
/*
* Two print routines -- one for use from DDB and DDB-like contexts, the
* other for use in the live kernel.
*/
void
stack_sbuf_print(struct sbuf *sb, struct stack *st)
{
char namebuf[64];
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
(void)stack_symbol(st->pcs[i], namebuf, sizeof(namebuf),
&offset);
sbuf_printf(sb, "#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
namebuf, offset);
}
}
#ifdef DDB
void
stack_sbuf_print_ddb(struct sbuf *sb, struct stack *st)
{
const char *name;
long offset;
int i;
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
for (i = 0; i < st->depth; i++) {
(void)stack_symbol_ddb(st->pcs[i], &name, &offset);
sbuf_printf(sb, "#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
name, offset);
}
}
#endif
#ifdef KTR
void
stack_ktr(u_int mask, const char *file, int line, struct stack *st, u_int depth,
int cheap)
{
#ifdef DDB
const char *name;
long offset;
int i;
#endif
KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
if (cheap) {
ktr_tracepoint(mask, file, line, "#0 %p %p %p %p %p %p",
st->pcs[0], st->pcs[1], st->pcs[2], st->pcs[3],
st->pcs[4], st->pcs[5]);
if (st->depth <= 6)
return;
ktr_tracepoint(mask, file, line, "#1 %p %p %p %p %p %p",
st->pcs[6], st->pcs[7], st->pcs[8], st->pcs[9],
st->pcs[10], st->pcs[11]);
if (st->depth <= 12)
return;
ktr_tracepoint(mask, file, line, "#2 %p %p %p %p %p %p",
st->pcs[12], st->pcs[13], st->pcs[14], st->pcs[15],
st->pcs[16], st->pcs[17]);
#ifdef DDB
} else {
if (depth == 0 || st->depth < depth)
depth = st->depth;
for (i = 0; i < depth; i++) {
(void)stack_symbol_ddb(st->pcs[i], &name, &offset);
ktr_tracepoint(mask, file, line, "#%d %p at %s+%#lx",
i, st->pcs[i], (u_long)name, offset, 0, 0);
}
#endif
}
}
#endif
/*
* Two variants of stack symbol lookup -- one that uses the DDB interfaces
* and bypasses linker locking, and the other that doesn't.
*/
static int
stack_symbol(vm_offset_t pc, char *namebuf, u_int buflen, long *offset)
{
if (linker_search_symbol_name((caddr_t)pc, namebuf, buflen,
offset) != 0) {
*offset = 0;
strlcpy(namebuf, "??", buflen);
return (ENOENT);
} else
return (0);
}
static int
stack_symbol_ddb(vm_offset_t pc, const char **name, long *offset)
{
linker_symval_t symval;
c_linker_sym_t sym;
if (linker_ddb_search_symbol((caddr_t)pc, &sym, offset) != 0)
goto out;
if (linker_ddb_symbol_values(sym, &symval) != 0)
goto out;
if (symval.name != NULL) {
*name = symval.name;
return (0);
}
out:
*offset = 0;
*name = "??";
return (ENOENT);
}