1174910Srwatson/*- 2174910Srwatson * Copyright (c) 2007 Robert N. M. Watson 3174910Srwatson * All rights reserved. 4174910Srwatson * 5174910Srwatson * Redistribution and use in source and binary forms, with or without 6174910Srwatson * modification, are permitted provided that the following conditions 7174910Srwatson * are met: 8174910Srwatson * 1. Redistributions of source code must retain the above copyright 9174910Srwatson * notice, this list of conditions and the following disclaimer. 10174910Srwatson * 2. Redistributions in binary form must reproduce the above copyright 11174910Srwatson * notice, this list of conditions and the following disclaimer in the 12174910Srwatson * documentation and/or other materials provided with the distribution. 13174910Srwatson * 14174910Srwatson * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15174910Srwatson * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16174910Srwatson * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17174910Srwatson * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18174910Srwatson * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19174910Srwatson * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20174910Srwatson * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21174910Srwatson * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22174910Srwatson * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23174910Srwatson * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24174910Srwatson * SUCH DAMAGE. 25174910Srwatson */ 26174910Srwatson 27174910Srwatson/* 28174910Srwatson * DDB capture support: capture kernel debugger output into a fixed-size 29174910Srwatson * buffer for later dumping to disk or extraction from user space. 30174910Srwatson */ 31174910Srwatson 32174910Srwatson#include <sys/cdefs.h> 33174910Srwatson__FBSDID("$FreeBSD$"); 34174910Srwatson 35175694Srwatson#include "opt_ddb.h" 36175694Srwatson 37174910Srwatson#include <sys/param.h> 38174910Srwatson#include <sys/conf.h> 39174910Srwatson#include <sys/kernel.h> 40174910Srwatson#include <sys/kerneldump.h> 41174910Srwatson#include <sys/malloc.h> 42174910Srwatson#include <sys/msgbuf.h> 43174910Srwatson#include <sys/priv.h> 44174910Srwatson#include <sys/sx.h> 45174910Srwatson#include <sys/sysctl.h> 46174910Srwatson#include <sys/systm.h> 47174910Srwatson 48174910Srwatson#include <ddb/ddb.h> 49174910Srwatson#include <ddb/db_lex.h> 50174910Srwatson 51174910Srwatson/* 52174910Srwatson * While it would be desirable to use a small block-sized buffer and dump 53174910Srwatson * incrementally to disk in fixed-size blocks, it's not possible to enter 54174910Srwatson * kernel dumper routines without restarting the kernel, which is undesirable 55174910Srwatson * in the midst of debugging. Instead, we maintain a large static global 56174910Srwatson * buffer that we fill from DDB's output routines. 57175694Srwatson * 58175694Srwatson * We enforce an invariant at runtime that buffer sizes are even multiples of 59175694Srwatson * the textdump block size, which is a design choice that we might want to 60175694Srwatson * reconsider. 61174910Srwatson */ 62175684Srwatsonstatic MALLOC_DEFINE(M_DDB_CAPTURE, "ddb_capture", "DDB capture buffer"); 63174910Srwatson 64175694Srwatson#ifndef DDB_CAPTURE_DEFAULTBUFSIZE 65175684Srwatson#define DDB_CAPTURE_DEFAULTBUFSIZE 48*1024 66175694Srwatson#endif 67175694Srwatson#ifndef DDB_CAPTURE_MAXBUFSIZE 68175699Srwatson#define DDB_CAPTURE_MAXBUFSIZE 5*1024*1024 69175694Srwatson#endif 70175684Srwatson#define DDB_CAPTURE_FILENAME "ddb.txt" /* Captured DDB output. */ 71174910Srwatson 72174910Srwatsonstatic char *db_capture_buf; 73175684Srwatsonstatic u_int db_capture_bufsize = DDB_CAPTURE_DEFAULTBUFSIZE; 74175684Srwatsonstatic u_int db_capture_maxbufsize = DDB_CAPTURE_MAXBUFSIZE; /* Read-only. */ 75174910Srwatsonstatic u_int db_capture_bufoff; /* Next location to write in buffer. */ 76174921Srwatsonstatic u_int db_capture_bufpadding; /* Amount of zero padding. */ 77174910Srwatsonstatic int db_capture_inpager; /* Suspend capture in pager. */ 78174910Srwatsonstatic int db_capture_inprogress; /* DDB capture currently in progress. */ 79174910Srwatson 80174910Srwatsonstruct sx db_capture_sx; /* Lock against user thread races. */ 81174910SrwatsonSX_SYSINIT(db_capture_sx, &db_capture_sx, "db_capture_sx"); 82174910Srwatson 83174910Srwatsonstatic SYSCTL_NODE(_debug_ddb, OID_AUTO, capture, CTLFLAG_RW, 0, 84174910Srwatson "DDB capture options"); 85174910Srwatson 86178492SrwatsonSYSCTL_UINT(_debug_ddb_capture, OID_AUTO, bufoff, CTLFLAG_RD, 87174910Srwatson &db_capture_bufoff, 0, "Bytes of data in DDB capture buffer"); 88174910Srwatson 89174910SrwatsonSYSCTL_UINT(_debug_ddb_capture, OID_AUTO, maxbufsize, CTLFLAG_RD, 90174910Srwatson &db_capture_maxbufsize, 0, 91174910Srwatson "Maximum value for debug.ddb.capture.bufsize"); 92174910Srwatson 93217326SmdfSYSCTL_INT(_debug_ddb_capture, OID_AUTO, inprogress, CTLFLAG_RD, 94178492Srwatson &db_capture_inprogress, 0, "DDB output capture in progress"); 95178492Srwatson 96174910Srwatson/* 97175694Srwatson * Boot-time allocation of the DDB capture buffer, if any. Force all buffer 98175694Srwatson * sizes, including the maximum size, to be rounded to block sizes. 99174921Srwatson */ 100174910Srwatsonstatic void 101174910Srwatsondb_capture_sysinit(__unused void *dummy) 102174910Srwatson{ 103174910Srwatson 104174910Srwatson TUNABLE_INT_FETCH("debug.ddb.capture.bufsize", &db_capture_bufsize); 105175694Srwatson db_capture_maxbufsize = roundup(db_capture_maxbufsize, 106175694Srwatson TEXTDUMP_BLOCKSIZE); 107174921Srwatson db_capture_bufsize = roundup(db_capture_bufsize, TEXTDUMP_BLOCKSIZE); 108175694Srwatson if (db_capture_bufsize > db_capture_maxbufsize) 109175694Srwatson db_capture_bufsize = db_capture_maxbufsize; 110174910Srwatson if (db_capture_bufsize != 0) 111175684Srwatson db_capture_buf = malloc(db_capture_bufsize, M_DDB_CAPTURE, 112174910Srwatson M_WAITOK); 113174910Srwatson} 114174910SrwatsonSYSINIT(db_capture, SI_SUB_DDB_SERVICES, SI_ORDER_ANY, db_capture_sysinit, 115174910Srwatson NULL); 116174910Srwatson 117174910Srwatson/* 118174910Srwatson * Run-time adjustment of the capture buffer. 119174910Srwatson */ 120174910Srwatsonstatic int 121174910Srwatsonsysctl_debug_ddb_capture_bufsize(SYSCTL_HANDLER_ARGS) 122174910Srwatson{ 123174910Srwatson u_int len, size; 124174910Srwatson char *buf; 125174910Srwatson int error; 126174910Srwatson 127174910Srwatson size = db_capture_bufsize; 128174910Srwatson error = sysctl_handle_int(oidp, &size, 0, req); 129174910Srwatson if (error || req->newptr == NULL) 130174910Srwatson return (error); 131174921Srwatson size = roundup(size, TEXTDUMP_BLOCKSIZE); 132175694Srwatson if (size > db_capture_maxbufsize) 133174910Srwatson return (EINVAL); 134174910Srwatson sx_xlock(&db_capture_sx); 135174910Srwatson if (size != 0) { 136174910Srwatson /* 137174910Srwatson * Potentially the buffer is quite large, so if we can't 138174910Srwatson * allocate it, fail rather than waiting. 139174910Srwatson */ 140175684Srwatson buf = malloc(size, M_DDB_CAPTURE, M_NOWAIT); 141174910Srwatson if (buf == NULL) { 142174910Srwatson sx_xunlock(&db_capture_sx); 143174910Srwatson return (ENOMEM); 144174910Srwatson } 145174910Srwatson len = min(db_capture_bufoff, size); 146174910Srwatson } else { 147174910Srwatson buf = NULL; 148174910Srwatson len = 0; 149174910Srwatson } 150174910Srwatson if (db_capture_buf != NULL && buf != NULL) 151174910Srwatson bcopy(db_capture_buf, buf, len); 152174910Srwatson if (db_capture_buf != NULL) 153175684Srwatson free(db_capture_buf, M_DDB_CAPTURE); 154174910Srwatson db_capture_bufoff = len; 155174910Srwatson db_capture_buf = buf; 156174910Srwatson db_capture_bufsize = size; 157174910Srwatson sx_xunlock(&db_capture_sx); 158174910Srwatson 159174910Srwatson KASSERT(db_capture_bufoff <= db_capture_bufsize, 160174910Srwatson ("sysctl_debug_ddb_capture_bufsize: bufoff > bufsize")); 161175694Srwatson KASSERT(db_capture_bufsize <= db_capture_maxbufsize, 162174910Srwatson ("sysctl_debug_ddb_capture_maxbufsize: bufsize > maxbufsize")); 163174910Srwatson 164174910Srwatson return (0); 165174910Srwatson} 166174910SrwatsonSYSCTL_PROC(_debug_ddb_capture, OID_AUTO, bufsize, CTLTYPE_UINT|CTLFLAG_RW, 167174910Srwatson 0, 0, sysctl_debug_ddb_capture_bufsize, "IU", 168174910Srwatson "Size of DDB capture buffer"); 169174910Srwatson 170174910Srwatson/* 171174910Srwatson * Sysctl to read out the capture buffer from userspace. We require 172174910Srwatson * privilege as sensitive process/memory information may be accessed. 173174910Srwatson */ 174174910Srwatsonstatic int 175174910Srwatsonsysctl_debug_ddb_capture_data(SYSCTL_HANDLER_ARGS) 176174910Srwatson{ 177174910Srwatson int error; 178174910Srwatson char ch; 179174910Srwatson 180174910Srwatson error = priv_check(req->td, PRIV_DDB_CAPTURE); 181174910Srwatson if (error) 182174910Srwatson return (error); 183174910Srwatson 184174910Srwatson sx_slock(&db_capture_sx); 185174910Srwatson error = SYSCTL_OUT(req, db_capture_buf, db_capture_bufoff); 186174910Srwatson sx_sunlock(&db_capture_sx); 187174910Srwatson if (error) 188174910Srwatson return (error); 189174910Srwatson ch = '\0'; 190174910Srwatson return (SYSCTL_OUT(req, &ch, sizeof(ch))); 191174910Srwatson} 192174910SrwatsonSYSCTL_PROC(_debug_ddb_capture, OID_AUTO, data, CTLTYPE_STRING | CTLFLAG_RD, 193174910Srwatson NULL, 0, sysctl_debug_ddb_capture_data, "A", "DDB capture data"); 194174910Srwatson 195174910Srwatson/* 196174910Srwatson * Routines for capturing DDB output into a fixed-size buffer. These are 197174910Srwatson * invoked from DDB's input and output routines. If we hit the limit on the 198174910Srwatson * buffer, we simply drop further data. 199174910Srwatson */ 200174910Srwatsonvoid 201174910Srwatsondb_capture_write(char *buffer, u_int buflen) 202174910Srwatson{ 203174910Srwatson u_int len; 204174910Srwatson 205174910Srwatson if (db_capture_inprogress == 0 || db_capture_inpager) 206174910Srwatson return; 207174910Srwatson len = min(buflen, db_capture_bufsize - db_capture_bufoff); 208174910Srwatson bcopy(buffer, db_capture_buf + db_capture_bufoff, len); 209174910Srwatson db_capture_bufoff += len; 210174910Srwatson 211174910Srwatson KASSERT(db_capture_bufoff <= db_capture_bufsize, 212174910Srwatson ("db_capture_write: bufoff > bufsize")); 213174910Srwatson} 214174910Srwatson 215174910Srwatsonvoid 216174910Srwatsondb_capture_writech(char ch) 217174910Srwatson{ 218174910Srwatson 219174910Srwatson return (db_capture_write(&ch, sizeof(ch))); 220174910Srwatson} 221174910Srwatson 222174910Srwatsonvoid 223174910Srwatsondb_capture_enterpager(void) 224174910Srwatson{ 225174910Srwatson 226174910Srwatson db_capture_inpager = 1; 227174910Srwatson} 228174910Srwatson 229174910Srwatsonvoid 230174910Srwatsondb_capture_exitpager(void) 231174910Srwatson{ 232174910Srwatson 233174910Srwatson db_capture_inpager = 0; 234174910Srwatson} 235174910Srwatson 236174910Srwatson/* 237174921Srwatson * Zero out any bytes left in the last block of the DDB capture buffer. This 238174921Srwatson * is run shortly before writing the blocks to disk, rather than when output 239174921Srwatson * capture is stopped, in order to avoid injecting nul's into the middle of 240174921Srwatson * output. 241174921Srwatson */ 242174921Srwatsonstatic void 243174921Srwatsondb_capture_zeropad(void) 244174921Srwatson{ 245174921Srwatson u_int len; 246174921Srwatson 247174921Srwatson len = min(TEXTDUMP_BLOCKSIZE, (db_capture_bufsize - 248174921Srwatson db_capture_bufoff) % TEXTDUMP_BLOCKSIZE); 249174921Srwatson bzero(db_capture_buf + db_capture_bufoff, len); 250174921Srwatson db_capture_bufpadding = len; 251174921Srwatson} 252174921Srwatson 253174921Srwatson/* 254174910Srwatson * Reset capture state, which flushes buffers. 255174910Srwatson */ 256174910Srwatsonstatic void 257174910Srwatsondb_capture_reset(void) 258174910Srwatson{ 259174910Srwatson 260174910Srwatson db_capture_inprogress = 0; 261174910Srwatson db_capture_bufoff = 0; 262174921Srwatson db_capture_bufpadding = 0; 263174910Srwatson} 264174910Srwatson 265174910Srwatson/* 266174910Srwatson * Start capture. Only one session is allowed at any time, but we may 267174910Srwatson * continue a previous session, so the buffer isn't reset. 268174910Srwatson */ 269174910Srwatsonstatic void 270174910Srwatsondb_capture_start(void) 271174910Srwatson{ 272174910Srwatson 273174910Srwatson if (db_capture_inprogress) { 274174910Srwatson db_printf("Capture already started\n"); 275174910Srwatson return; 276174910Srwatson } 277174910Srwatson db_capture_inprogress = 1; 278174910Srwatson} 279174910Srwatson 280174910Srwatson/* 281174921Srwatson * Terminate DDB output capture--real work is deferred to db_capture_dump, 282174921Srwatson * which executes outside of the DDB context. We don't zero pad here because 283174921Srwatson * capture may be started again before the dump takes place. 284174910Srwatson */ 285174910Srwatsonstatic void 286174910Srwatsondb_capture_stop(void) 287174910Srwatson{ 288174910Srwatson 289174910Srwatson if (db_capture_inprogress == 0) { 290174910Srwatson db_printf("Capture not started\n"); 291174910Srwatson return; 292174910Srwatson } 293174910Srwatson db_capture_inprogress = 0; 294174910Srwatson} 295174910Srwatson 296174921Srwatson/* 297174921Srwatson * Dump DDB(4) captured output (and resets capture buffers). 298174921Srwatson */ 299174921Srwatsonvoid 300174921Srwatsondb_capture_dump(struct dumperinfo *di) 301174921Srwatson{ 302174921Srwatson u_int offset; 303174921Srwatson 304174921Srwatson if (db_capture_bufoff == 0) 305174921Srwatson return; 306174921Srwatson 307174921Srwatson db_capture_zeropad(); 308175684Srwatson textdump_mkustar(textdump_block_buffer, DDB_CAPTURE_FILENAME, 309174921Srwatson db_capture_bufoff); 310174921Srwatson (void)textdump_writenextblock(di, textdump_block_buffer); 311174921Srwatson for (offset = 0; offset < db_capture_bufoff + db_capture_bufpadding; 312174921Srwatson offset += TEXTDUMP_BLOCKSIZE) 313174921Srwatson (void)textdump_writenextblock(di, db_capture_buf + offset); 314174921Srwatson db_capture_bufoff = 0; 315174921Srwatson db_capture_bufpadding = 0; 316174921Srwatson} 317174921Srwatson 318174910Srwatson/*- 319174910Srwatson * DDB(4) command to manage capture: 320174910Srwatson * 321174910Srwatson * capture on - start DDB output capture 322174910Srwatson * capture off - stop DDB output capture 323174910Srwatson * capture reset - reset DDB capture buffer (also stops capture) 324174910Srwatson * capture status - print DDB output capture status 325174910Srwatson */ 326174910Srwatsonstatic void 327174910Srwatsondb_capture_usage(void) 328174910Srwatson{ 329174910Srwatson 330174910Srwatson db_error("capture [on|off|reset|status]\n"); 331174910Srwatson} 332174910Srwatson 333174910Srwatsonvoid 334174910Srwatsondb_capture_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, 335174910Srwatson char *modif) 336174910Srwatson{ 337174910Srwatson int t; 338174910Srwatson 339174910Srwatson t = db_read_token(); 340174910Srwatson if (t != tIDENT) { 341174910Srwatson db_capture_usage(); 342174910Srwatson return; 343174910Srwatson } 344174910Srwatson if (db_read_token() != tEOL) 345174910Srwatson db_error("?\n"); 346174910Srwatson if (strcmp(db_tok_string, "on") == 0) 347174910Srwatson db_capture_start(); 348174910Srwatson else if (strcmp(db_tok_string, "off") == 0) 349174910Srwatson db_capture_stop(); 350174910Srwatson else if (strcmp(db_tok_string, "reset") == 0) 351174910Srwatson db_capture_reset(); 352174910Srwatson else if (strcmp(db_tok_string, "status") == 0) { 353174910Srwatson db_printf("%u/%u bytes used\n", db_capture_bufoff, 354174910Srwatson db_capture_bufsize); 355174910Srwatson if (db_capture_inprogress) 356174910Srwatson db_printf("capture is on\n"); 357174910Srwatson else 358174910Srwatson db_printf("capture is off\n"); 359174910Srwatson } else 360174910Srwatson db_capture_usage(); 361174910Srwatson} 362