subr_stack.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * 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>
#include <sys/sysctl.h>
 
FEATURE(stack, "Support for capturing kernel stack");
 
MALLOC_DEFINE(M_STACK, "stack", "Stack Traces");
 
static int stack_symbol(vm_offset_t pc, char *namebuf, u_int buflen,
            long *offset, int flags);
static int stack_symbol_ddb(vm_offset_t pc, const char **name, long *offset);
 
struct stack *
stack_create(int flags)
{
        struct stack *st;
 
        st = malloc(sizeof(*st), M_STACK, flags | 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(const struct stack *src, struct stack *dst)
{
 
        *dst = *src;
}
 
void
stack_zero(struct stack *st)
{
 
        bzero(st, sizeof *st);
}
 
void
stack_print(const 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, M_WAITOK);
                printf("#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
                    namebuf, offset);
        }
}
 
void
stack_print_short(const 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, M_WAITOK) == 0)
                        printf("%s+%#lx", namebuf, offset);
                else
                        printf("%p", (void *)st->pcs[i]);
        }
        printf("\n");
}
 
void
stack_print_ddb(const 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);
        }
}
 
#if defined(DDB) || defined(WITNESS)
void
stack_print_short_ddb(const 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
 
/*
 * Format stack into sbuf from live kernel.
 *
 * flags - M_WAITOK or M_NOWAIT (EWOULDBLOCK).
 */
int
stack_sbuf_print_flags(struct sbuf *sb, const struct stack *st, int flags,
    enum stack_sbuf_fmt format)
{
        char namebuf[64];
        long offset;
        int i, error;
 
        KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
        for (i = 0; i < st->depth; i++) {
                error = stack_symbol(st->pcs[i], namebuf, sizeof(namebuf),
                    &offset, flags);
                if (error == EWOULDBLOCK)
                        return (error);
                switch (format) {
                case STACK_SBUF_FMT_LONG:
                        sbuf_printf(sb, "#%d %p at %s+%#lx\n", i,
                            (void *)st->pcs[i], namebuf, offset);
                        break;
                case STACK_SBUF_FMT_COMPACT:
                        sbuf_printf(sb, "%s+%#lx ", namebuf, offset);
                        break;
                default:
                        __assert_unreachable();
                }
        }
        sbuf_nl_terminate(sb);
        return (0);
}
 
void
stack_sbuf_print(struct sbuf *sb, const struct stack *st)
{
 
        (void)stack_sbuf_print_flags(sb, st, M_WAITOK, STACK_SBUF_FMT_LONG);
}
 
#if defined(DDB) || defined(WITNESS)
void
stack_sbuf_print_ddb(struct sbuf *sb, const 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, const struct stack *st,
    u_int depth)
{
#ifdef DDB
        const char *name;
        long offset;
        int i;
#endif
 
        KASSERT(st->depth <= STACK_MAX, ("bogus stack"));
#ifdef DDB
        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,
    int flags)
{
        int error;
 
        error = linker_search_symbol_name_flags((caddr_t)pc, namebuf, buflen,
            offset, flags);
        if (error == 0 || error == EWOULDBLOCK)
                return (error);
 
        *offset = 0;
        strlcpy(namebuf, "??", buflen);
        return (ENOENT);
}
 
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);
}