db_capture.c revision 175699
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: head/sys/ddb/db_capture.c 175699 2008-01-26 23:02:14Z rwatson $"); 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 86174910SrwatsonSYSCTL_UINT(_debug_ddb_capture, OID_AUTO, bytes, 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 93174910Srwatson/* 94175694Srwatson * Boot-time allocation of the DDB capture buffer, if any. Force all buffer 95175694Srwatson * sizes, including the maximum size, to be rounded to block sizes. 96174921Srwatson */ 97174910Srwatsonstatic void 98174910Srwatsondb_capture_sysinit(__unused void *dummy) 99174910Srwatson{ 100174910Srwatson 101174910Srwatson TUNABLE_INT_FETCH("debug.ddb.capture.bufsize", &db_capture_bufsize); 102175694Srwatson db_capture_maxbufsize = roundup(db_capture_maxbufsize, 103175694Srwatson TEXTDUMP_BLOCKSIZE); 104174921Srwatson db_capture_bufsize = roundup(db_capture_bufsize, TEXTDUMP_BLOCKSIZE); 105175694Srwatson if (db_capture_bufsize > db_capture_maxbufsize) 106175694Srwatson db_capture_bufsize = db_capture_maxbufsize; 107174910Srwatson if (db_capture_bufsize != 0) 108175684Srwatson db_capture_buf = malloc(db_capture_bufsize, M_DDB_CAPTURE, 109174910Srwatson M_WAITOK); 110174910Srwatson} 111174910SrwatsonSYSINIT(db_capture, SI_SUB_DDB_SERVICES, SI_ORDER_ANY, db_capture_sysinit, 112174910Srwatson NULL); 113174910Srwatson 114174910Srwatson/* 115174910Srwatson * Run-time adjustment of the capture buffer. 116174910Srwatson */ 117174910Srwatsonstatic int 118174910Srwatsonsysctl_debug_ddb_capture_bufsize(SYSCTL_HANDLER_ARGS) 119174910Srwatson{ 120174910Srwatson u_int len, size; 121174910Srwatson char *buf; 122174910Srwatson int error; 123174910Srwatson 124174910Srwatson size = db_capture_bufsize; 125174910Srwatson error = sysctl_handle_int(oidp, &size, 0, req); 126174910Srwatson if (error || req->newptr == NULL) 127174910Srwatson return (error); 128174921Srwatson size = roundup(size, TEXTDUMP_BLOCKSIZE); 129175694Srwatson if (size > db_capture_maxbufsize) 130174910Srwatson return (EINVAL); 131174910Srwatson sx_xlock(&db_capture_sx); 132174910Srwatson if (size != 0) { 133174910Srwatson /* 134174910Srwatson * Potentially the buffer is quite large, so if we can't 135174910Srwatson * allocate it, fail rather than waiting. 136174910Srwatson */ 137175684Srwatson buf = malloc(size, M_DDB_CAPTURE, M_NOWAIT); 138174910Srwatson if (buf == NULL) { 139174910Srwatson sx_xunlock(&db_capture_sx); 140174910Srwatson return (ENOMEM); 141174910Srwatson } 142174910Srwatson len = min(db_capture_bufoff, size); 143174910Srwatson } else { 144174910Srwatson buf = NULL; 145174910Srwatson len = 0; 146174910Srwatson } 147174910Srwatson if (db_capture_buf != NULL && buf != NULL) 148174910Srwatson bcopy(db_capture_buf, buf, len); 149174910Srwatson if (db_capture_buf != NULL) 150175684Srwatson free(db_capture_buf, M_DDB_CAPTURE); 151174910Srwatson db_capture_bufoff = len; 152174910Srwatson db_capture_buf = buf; 153174910Srwatson db_capture_bufsize = size; 154174910Srwatson sx_xunlock(&db_capture_sx); 155174910Srwatson 156174910Srwatson KASSERT(db_capture_bufoff <= db_capture_bufsize, 157174910Srwatson ("sysctl_debug_ddb_capture_bufsize: bufoff > bufsize")); 158175694Srwatson KASSERT(db_capture_bufsize <= db_capture_maxbufsize, 159174910Srwatson ("sysctl_debug_ddb_capture_maxbufsize: bufsize > maxbufsize")); 160174910Srwatson 161174910Srwatson return (0); 162174910Srwatson} 163174910SrwatsonSYSCTL_PROC(_debug_ddb_capture, OID_AUTO, bufsize, CTLTYPE_UINT|CTLFLAG_RW, 164174910Srwatson 0, 0, sysctl_debug_ddb_capture_bufsize, "IU", 165174910Srwatson "Size of DDB capture buffer"); 166174910Srwatson 167174910Srwatson/* 168174910Srwatson * Sysctl to read out the capture buffer from userspace. We require 169174910Srwatson * privilege as sensitive process/memory information may be accessed. 170174910Srwatson */ 171174910Srwatsonstatic int 172174910Srwatsonsysctl_debug_ddb_capture_data(SYSCTL_HANDLER_ARGS) 173174910Srwatson{ 174174910Srwatson int error; 175174910Srwatson char ch; 176174910Srwatson 177174910Srwatson error = priv_check(req->td, PRIV_DDB_CAPTURE); 178174910Srwatson if (error) 179174910Srwatson return (error); 180174910Srwatson 181174910Srwatson sx_slock(&db_capture_sx); 182174910Srwatson error = SYSCTL_OUT(req, db_capture_buf, db_capture_bufoff); 183174910Srwatson sx_sunlock(&db_capture_sx); 184174910Srwatson if (error) 185174910Srwatson return (error); 186174910Srwatson ch = '\0'; 187174910Srwatson return (SYSCTL_OUT(req, &ch, sizeof(ch))); 188174910Srwatson} 189174910SrwatsonSYSCTL_PROC(_debug_ddb_capture, OID_AUTO, data, CTLTYPE_STRING | CTLFLAG_RD, 190174910Srwatson NULL, 0, sysctl_debug_ddb_capture_data, "A", "DDB capture data"); 191174910Srwatson 192174910Srwatson/* 193174910Srwatson * Routines for capturing DDB output into a fixed-size buffer. These are 194174910Srwatson * invoked from DDB's input and output routines. If we hit the limit on the 195174910Srwatson * buffer, we simply drop further data. 196174910Srwatson */ 197174910Srwatsonvoid 198174910Srwatsondb_capture_write(char *buffer, u_int buflen) 199174910Srwatson{ 200174910Srwatson u_int len; 201174910Srwatson 202174910Srwatson if (db_capture_inprogress == 0 || db_capture_inpager) 203174910Srwatson return; 204174910Srwatson len = min(buflen, db_capture_bufsize - db_capture_bufoff); 205174910Srwatson bcopy(buffer, db_capture_buf + db_capture_bufoff, len); 206174910Srwatson db_capture_bufoff += len; 207174910Srwatson 208174910Srwatson KASSERT(db_capture_bufoff <= db_capture_bufsize, 209174910Srwatson ("db_capture_write: bufoff > bufsize")); 210174910Srwatson} 211174910Srwatson 212174910Srwatsonvoid 213174910Srwatsondb_capture_writech(char ch) 214174910Srwatson{ 215174910Srwatson 216174910Srwatson return (db_capture_write(&ch, sizeof(ch))); 217174910Srwatson} 218174910Srwatson 219174910Srwatsonvoid 220174910Srwatsondb_capture_enterpager(void) 221174910Srwatson{ 222174910Srwatson 223174910Srwatson db_capture_inpager = 1; 224174910Srwatson} 225174910Srwatson 226174910Srwatsonvoid 227174910Srwatsondb_capture_exitpager(void) 228174910Srwatson{ 229174910Srwatson 230174910Srwatson db_capture_inpager = 0; 231174910Srwatson} 232174910Srwatson 233174910Srwatson/* 234174921Srwatson * Zero out any bytes left in the last block of the DDB capture buffer. This 235174921Srwatson * is run shortly before writing the blocks to disk, rather than when output 236174921Srwatson * capture is stopped, in order to avoid injecting nul's into the middle of 237174921Srwatson * output. 238174921Srwatson */ 239174921Srwatsonstatic void 240174921Srwatsondb_capture_zeropad(void) 241174921Srwatson{ 242174921Srwatson u_int len; 243174921Srwatson 244174921Srwatson len = min(TEXTDUMP_BLOCKSIZE, (db_capture_bufsize - 245174921Srwatson db_capture_bufoff) % TEXTDUMP_BLOCKSIZE); 246174921Srwatson bzero(db_capture_buf + db_capture_bufoff, len); 247174921Srwatson db_capture_bufpadding = len; 248174921Srwatson} 249174921Srwatson 250174921Srwatson/* 251174910Srwatson * Reset capture state, which flushes buffers. 252174910Srwatson */ 253174910Srwatsonstatic void 254174910Srwatsondb_capture_reset(void) 255174910Srwatson{ 256174910Srwatson 257174910Srwatson db_capture_inprogress = 0; 258174910Srwatson db_capture_bufoff = 0; 259174921Srwatson db_capture_bufpadding = 0; 260174910Srwatson} 261174910Srwatson 262174910Srwatson/* 263174910Srwatson * Start capture. Only one session is allowed at any time, but we may 264174910Srwatson * continue a previous session, so the buffer isn't reset. 265174910Srwatson */ 266174910Srwatsonstatic void 267174910Srwatsondb_capture_start(void) 268174910Srwatson{ 269174910Srwatson 270174910Srwatson if (db_capture_inprogress) { 271174910Srwatson db_printf("Capture already started\n"); 272174910Srwatson return; 273174910Srwatson } 274174910Srwatson db_capture_inprogress = 1; 275174910Srwatson} 276174910Srwatson 277174910Srwatson/* 278174921Srwatson * Terminate DDB output capture--real work is deferred to db_capture_dump, 279174921Srwatson * which executes outside of the DDB context. We don't zero pad here because 280174921Srwatson * capture may be started again before the dump takes place. 281174910Srwatson */ 282174910Srwatsonstatic void 283174910Srwatsondb_capture_stop(void) 284174910Srwatson{ 285174910Srwatson 286174910Srwatson if (db_capture_inprogress == 0) { 287174910Srwatson db_printf("Capture not started\n"); 288174910Srwatson return; 289174910Srwatson } 290174910Srwatson db_capture_inprogress = 0; 291174910Srwatson} 292174910Srwatson 293174921Srwatson/* 294174921Srwatson * Dump DDB(4) captured output (and resets capture buffers). 295174921Srwatson */ 296174921Srwatsonvoid 297174921Srwatsondb_capture_dump(struct dumperinfo *di) 298174921Srwatson{ 299174921Srwatson u_int offset; 300174921Srwatson 301174921Srwatson if (db_capture_bufoff == 0) 302174921Srwatson return; 303174921Srwatson 304174921Srwatson db_capture_zeropad(); 305175684Srwatson textdump_mkustar(textdump_block_buffer, DDB_CAPTURE_FILENAME, 306174921Srwatson db_capture_bufoff); 307174921Srwatson (void)textdump_writenextblock(di, textdump_block_buffer); 308174921Srwatson for (offset = 0; offset < db_capture_bufoff + db_capture_bufpadding; 309174921Srwatson offset += TEXTDUMP_BLOCKSIZE) 310174921Srwatson (void)textdump_writenextblock(di, db_capture_buf + offset); 311174921Srwatson db_capture_bufoff = 0; 312174921Srwatson db_capture_bufpadding = 0; 313174921Srwatson} 314174921Srwatson 315174910Srwatson/*- 316174910Srwatson * DDB(4) command to manage capture: 317174910Srwatson * 318174910Srwatson * capture on - start DDB output capture 319174910Srwatson * capture off - stop DDB output capture 320174910Srwatson * capture reset - reset DDB capture buffer (also stops capture) 321174910Srwatson * capture status - print DDB output capture status 322174910Srwatson */ 323174910Srwatsonstatic void 324174910Srwatsondb_capture_usage(void) 325174910Srwatson{ 326174910Srwatson 327174910Srwatson db_error("capture [on|off|reset|status]\n"); 328174910Srwatson} 329174910Srwatson 330174910Srwatsonvoid 331174910Srwatsondb_capture_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, 332174910Srwatson char *modif) 333174910Srwatson{ 334174910Srwatson int t; 335174910Srwatson 336174910Srwatson t = db_read_token(); 337174910Srwatson if (t != tIDENT) { 338174910Srwatson db_capture_usage(); 339174910Srwatson return; 340174910Srwatson } 341174910Srwatson if (db_read_token() != tEOL) 342174910Srwatson db_error("?\n"); 343174910Srwatson if (strcmp(db_tok_string, "on") == 0) 344174910Srwatson db_capture_start(); 345174910Srwatson else if (strcmp(db_tok_string, "off") == 0) 346174910Srwatson db_capture_stop(); 347174910Srwatson else if (strcmp(db_tok_string, "reset") == 0) 348174910Srwatson db_capture_reset(); 349174910Srwatson else if (strcmp(db_tok_string, "status") == 0) { 350174910Srwatson db_printf("%u/%u bytes used\n", db_capture_bufoff, 351174910Srwatson db_capture_bufsize); 352174910Srwatson if (db_capture_inprogress) 353174910Srwatson db_printf("capture is on\n"); 354174910Srwatson else 355174910Srwatson db_printf("capture is off\n"); 356174910Srwatson } else 357174910Srwatson db_capture_usage(); 358174910Srwatson} 359