361 lines
10 KiB
C
361 lines
10 KiB
C
/*-
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* Copyright (c) 2007 Robert N. M. Watson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* DDB capture support: capture kernel debugger output into a fixed-size
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* buffer for later dumping to disk or extraction from user space.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ddb.h"
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#include <sys/param.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/kerneldump.h>
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#include <sys/malloc.h>
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#include <sys/msgbuf.h>
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#include <sys/priv.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <ddb/ddb.h>
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#include <ddb/db_lex.h>
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/*
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* While it would be desirable to use a small block-sized buffer and dump
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* incrementally to disk in fixed-size blocks, it's not possible to enter
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* kernel dumper routines without restarting the kernel, which is undesirable
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* in the midst of debugging. Instead, we maintain a large static global
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* buffer that we fill from DDB's output routines.
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*
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* We enforce an invariant at runtime that buffer sizes are even multiples of
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* the textdump block size, which is a design choice that we might want to
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* reconsider.
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*/
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static MALLOC_DEFINE(M_DDB_CAPTURE, "ddb_capture", "DDB capture buffer");
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#ifndef DDB_CAPTURE_DEFAULTBUFSIZE
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#define DDB_CAPTURE_DEFAULTBUFSIZE 48*1024
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#endif
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#ifndef DDB_CAPTURE_MAXBUFSIZE
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#define DDB_CAPTURE_MAXBUFSIZE 5*1024*1024
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#endif
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#define DDB_CAPTURE_FILENAME "ddb.txt" /* Captured DDB output. */
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static char *db_capture_buf;
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static u_int db_capture_bufsize = DDB_CAPTURE_DEFAULTBUFSIZE;
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static u_int db_capture_maxbufsize = DDB_CAPTURE_MAXBUFSIZE; /* Read-only. */
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static u_int db_capture_bufoff; /* Next location to write in buffer. */
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static u_int db_capture_bufpadding; /* Amount of zero padding. */
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static int db_capture_inpager; /* Suspend capture in pager. */
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static int db_capture_inprogress; /* DDB capture currently in progress. */
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struct sx db_capture_sx; /* Lock against user thread races. */
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SX_SYSINIT(db_capture_sx, &db_capture_sx, "db_capture_sx");
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static SYSCTL_NODE(_debug_ddb, OID_AUTO, capture, CTLFLAG_RW, 0,
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"DDB capture options");
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SYSCTL_UINT(_debug_ddb_capture, OID_AUTO, bufoff, CTLFLAG_RD,
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&db_capture_bufoff, 0, "Bytes of data in DDB capture buffer");
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SYSCTL_UINT(_debug_ddb_capture, OID_AUTO, maxbufsize, CTLFLAG_RD,
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&db_capture_maxbufsize, 0,
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"Maximum value for debug.ddb.capture.bufsize");
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SYSCTL_INT(_debug_ddb_capture, OID_AUTO, inprogress, CTLFLAG_RD,
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&db_capture_inprogress, 0, "DDB output capture in progress");
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/*
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* Boot-time allocation of the DDB capture buffer, if any. Force all buffer
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* sizes, including the maximum size, to be rounded to block sizes.
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*/
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static void
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db_capture_sysinit(__unused void *dummy)
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{
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TUNABLE_INT_FETCH("debug.ddb.capture.bufsize", &db_capture_bufsize);
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db_capture_maxbufsize = roundup(db_capture_maxbufsize,
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TEXTDUMP_BLOCKSIZE);
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db_capture_bufsize = roundup(db_capture_bufsize, TEXTDUMP_BLOCKSIZE);
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if (db_capture_bufsize > db_capture_maxbufsize)
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db_capture_bufsize = db_capture_maxbufsize;
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if (db_capture_bufsize != 0)
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db_capture_buf = malloc(db_capture_bufsize, M_DDB_CAPTURE,
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M_WAITOK);
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}
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SYSINIT(db_capture, SI_SUB_DDB_SERVICES, SI_ORDER_ANY, db_capture_sysinit,
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NULL);
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/*
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* Run-time adjustment of the capture buffer.
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*/
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static int
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sysctl_debug_ddb_capture_bufsize(SYSCTL_HANDLER_ARGS)
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{
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u_int len, size;
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char *buf;
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int error;
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size = db_capture_bufsize;
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error = sysctl_handle_int(oidp, &size, 0, req);
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if (error || req->newptr == NULL)
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return (error);
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size = roundup(size, TEXTDUMP_BLOCKSIZE);
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if (size > db_capture_maxbufsize)
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return (EINVAL);
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sx_xlock(&db_capture_sx);
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if (size != 0) {
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/*
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* Potentially the buffer is quite large, so if we can't
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* allocate it, fail rather than waiting.
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*/
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buf = malloc(size, M_DDB_CAPTURE, M_NOWAIT);
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if (buf == NULL) {
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sx_xunlock(&db_capture_sx);
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return (ENOMEM);
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}
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len = min(db_capture_bufoff, size);
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} else {
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buf = NULL;
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len = 0;
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}
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if (db_capture_buf != NULL && buf != NULL)
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bcopy(db_capture_buf, buf, len);
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if (db_capture_buf != NULL)
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free(db_capture_buf, M_DDB_CAPTURE);
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db_capture_bufoff = len;
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db_capture_buf = buf;
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db_capture_bufsize = size;
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sx_xunlock(&db_capture_sx);
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KASSERT(db_capture_bufoff <= db_capture_bufsize,
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("sysctl_debug_ddb_capture_bufsize: bufoff > bufsize"));
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KASSERT(db_capture_bufsize <= db_capture_maxbufsize,
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("sysctl_debug_ddb_capture_maxbufsize: bufsize > maxbufsize"));
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return (0);
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}
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SYSCTL_PROC(_debug_ddb_capture, OID_AUTO, bufsize, CTLTYPE_UINT|CTLFLAG_RW,
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0, 0, sysctl_debug_ddb_capture_bufsize, "IU",
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"Size of DDB capture buffer");
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/*
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* Sysctl to read out the capture buffer from userspace. We require
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* privilege as sensitive process/memory information may be accessed.
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*/
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static int
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sysctl_debug_ddb_capture_data(SYSCTL_HANDLER_ARGS)
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{
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int error;
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char ch;
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error = priv_check(req->td, PRIV_DDB_CAPTURE);
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if (error)
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return (error);
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sx_slock(&db_capture_sx);
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error = SYSCTL_OUT(req, db_capture_buf, db_capture_bufoff);
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sx_sunlock(&db_capture_sx);
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if (error)
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return (error);
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ch = '\0';
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return (SYSCTL_OUT(req, &ch, sizeof(ch)));
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}
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SYSCTL_PROC(_debug_ddb_capture, OID_AUTO, data, CTLTYPE_STRING | CTLFLAG_RD,
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NULL, 0, sysctl_debug_ddb_capture_data, "A", "DDB capture data");
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/*
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* Routines for capturing DDB output into a fixed-size buffer. These are
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* invoked from DDB's input and output routines. If we hit the limit on the
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* buffer, we simply drop further data.
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*/
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void
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db_capture_write(char *buffer, u_int buflen)
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{
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u_int len;
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if (db_capture_inprogress == 0 || db_capture_inpager)
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return;
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len = min(buflen, db_capture_bufsize - db_capture_bufoff);
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bcopy(buffer, db_capture_buf + db_capture_bufoff, len);
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db_capture_bufoff += len;
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KASSERT(db_capture_bufoff <= db_capture_bufsize,
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("db_capture_write: bufoff > bufsize"));
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}
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void
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db_capture_writech(char ch)
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{
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return (db_capture_write(&ch, sizeof(ch)));
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}
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void
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db_capture_enterpager(void)
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{
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db_capture_inpager = 1;
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}
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void
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db_capture_exitpager(void)
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{
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db_capture_inpager = 0;
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}
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/*
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* Zero out any bytes left in the last block of the DDB capture buffer. This
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* is run shortly before writing the blocks to disk, rather than when output
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* capture is stopped, in order to avoid injecting nul's into the middle of
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* output.
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*/
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static void
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db_capture_zeropad(void)
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{
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u_int len;
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len = min(TEXTDUMP_BLOCKSIZE, (db_capture_bufsize -
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db_capture_bufoff) % TEXTDUMP_BLOCKSIZE);
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bzero(db_capture_buf + db_capture_bufoff, len);
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db_capture_bufpadding = len;
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}
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/*
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* Reset capture state, which flushes buffers.
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*/
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static void
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db_capture_reset(void)
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{
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db_capture_inprogress = 0;
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db_capture_bufoff = 0;
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db_capture_bufpadding = 0;
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}
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/*
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* Start capture. Only one session is allowed at any time, but we may
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* continue a previous session, so the buffer isn't reset.
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*/
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static void
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db_capture_start(void)
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{
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if (db_capture_inprogress) {
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db_printf("Capture already started\n");
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return;
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}
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db_capture_inprogress = 1;
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}
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/*
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* Terminate DDB output capture--real work is deferred to db_capture_dump,
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* which executes outside of the DDB context. We don't zero pad here because
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* capture may be started again before the dump takes place.
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*/
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static void
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db_capture_stop(void)
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{
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if (db_capture_inprogress == 0) {
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db_printf("Capture not started\n");
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return;
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}
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db_capture_inprogress = 0;
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}
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/*
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* Dump DDB(4) captured output (and resets capture buffers).
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*/
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void
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db_capture_dump(struct dumperinfo *di)
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{
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u_int offset;
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if (db_capture_bufoff == 0)
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return;
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db_capture_zeropad();
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textdump_mkustar(textdump_block_buffer, DDB_CAPTURE_FILENAME,
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db_capture_bufoff);
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(void)textdump_writenextblock(di, textdump_block_buffer);
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for (offset = 0; offset < db_capture_bufoff + db_capture_bufpadding;
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offset += TEXTDUMP_BLOCKSIZE)
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(void)textdump_writenextblock(di, db_capture_buf + offset);
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db_capture_bufoff = 0;
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db_capture_bufpadding = 0;
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}
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/*-
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* DDB(4) command to manage capture:
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*
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* capture on - start DDB output capture
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* capture off - stop DDB output capture
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* capture reset - reset DDB capture buffer (also stops capture)
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* capture status - print DDB output capture status
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*/
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static void
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db_capture_usage(void)
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{
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db_error("capture [on|off|reset|status]\n");
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}
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void
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db_capture_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
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{
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int t;
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t = db_read_token();
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if (t != tIDENT) {
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db_capture_usage();
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return;
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}
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if (db_read_token() != tEOL)
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db_error("?\n");
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if (strcmp(db_tok_string, "on") == 0)
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db_capture_start();
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else if (strcmp(db_tok_string, "off") == 0)
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db_capture_stop();
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else if (strcmp(db_tok_string, "reset") == 0)
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db_capture_reset();
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else if (strcmp(db_tok_string, "status") == 0) {
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db_printf("%u/%u bytes used\n", db_capture_bufoff,
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db_capture_bufsize);
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if (db_capture_inprogress)
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db_printf("capture is on\n");
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else
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db_printf("capture is off\n");
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} else
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db_capture_usage();
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}
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