1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * Proc Service API Interposition Layer 31 * 32 * In order to allow multiple MDB targets to make use of librtld_db, we 33 * provide an interposition layer for functions in the proc_service.h API 34 * that are used by librtld_db. Each of the functions used by librtld_db 35 * can be conveniently expressed in terms of the MDB target API, so this 36 * layer simply selects the appropriate target, invokes the corresponding 37 * target API function, and then translates the error codes appropriately. 38 * We expect that each proc_service entry point will be invoked with a 39 * cookie (struct ps_prochandle *) which matches either a known MDB target, 40 * or the value of a target's t->t_pshandle. This allows us to re-vector 41 * calls to the proc service API around libproc (which also contains an 42 * implementation of the proc_service API) like this: 43 * 44 * Linker map: 45 * +---------+ +---------+ +------------+ Legend: 46 * | MDB | ->| libproc | ->| librtld_db | <1> function in this file 47 * +---------+ +---------+ +------------+ <2> function in libproc 48 * ps_pread<1> ps_pread<2> call ps_pread() --+ 49 * | 50 * +---------------------------------------------+ 51 * | 52 * +-> ps_pread<1>(P, ...) 53 * t = mdb_tgt_from_pshandle(P); 54 * mdb_tgt_vread(t, ...); 55 * 56 * If we are debugging a user process, we then make these calls (which form 57 * the equivalent of libproc's proc_service implementation): 58 * 59 * mdb_tgt_vread() -> proc target t->t_vread() -> libproc.so`Pread() 60 * 61 * If we are debugging a user process through a kernel crash dump (kproc 62 * target), we make these calls: 63 * 64 * mdb_tgt_vread() -> kproc target t->t_vread() -> mdb_tgt_aread(kvm target) -> 65 * kvm target t->t_aread() -> libkvm.so`kvm_aread() 66 * 67 * This design allows us to support both kproc's use of librtld_db, as well 68 * as libproc's use of librtld_db, but it does lead to one unfortunate problem 69 * in the creation of a proc target: when the proc target invokes libproc to 70 * construct a ps_prochandle, and libproc in turn invokes librtld_db, MDB does 71 * not yet know what ps_prochandle has been allocated inside of libproc since 72 * this call has not yet returned. We also can't translate this ps_prochandle 73 * to the target itself, since that target isn't ready to handle requests yet; 74 * we actually need to pass the call back through to libproc. In order to 75 * do that, we use libdl to lookup the address of libproc's definition of the 76 * various functions (RTLD_NEXT on the link map chain) and store these in the 77 * ps_ops structure below. If we ever fail to translate a ps_prochandle to 78 * an MDB target, we simply pass the call through to libproc. 79 */ 80 81 #include <proc_service.h> 82 #include <dlfcn.h> 83 84 #include <mdb/mdb_target_impl.h> 85 #include <mdb/mdb_debug.h> 86 #include <mdb/mdb.h> 87 88 static struct { 89 ps_err_e (*ps_pread)(struct ps_prochandle *, 90 psaddr_t, void *, size_t); 91 ps_err_e (*ps_pwrite)(struct ps_prochandle *, 92 psaddr_t, const void *, size_t); 93 ps_err_e (*ps_pglobal_lookup)(struct ps_prochandle *, 94 const char *, const char *, psaddr_t *); 95 ps_err_e (*ps_pglobal_sym)(struct ps_prochandle *P, 96 const char *, const char *, ps_sym_t *); 97 ps_err_e (*ps_pauxv)(struct ps_prochandle *, 98 const auxv_t **); 99 ps_err_e (*ps_pbrandname)(struct ps_prochandle *, 100 char *, size_t); 101 ps_err_e (*ps_pdmodel)(struct ps_prochandle *, 102 int *); 103 } ps_ops; 104 105 static mdb_tgt_t * 106 mdb_tgt_from_pshandle(void *P) 107 { 108 mdb_tgt_t *t; 109 110 for (t = mdb_list_next(&mdb.m_tgtlist); t; t = mdb_list_next(t)) { 111 if (t == P || t->t_pshandle == P) 112 return (t); 113 } 114 115 return (NULL); 116 } 117 118 /* 119 * Read from the specified target virtual address. 120 */ 121 ps_err_e 122 ps_pread(struct ps_prochandle *P, psaddr_t addr, void *buf, size_t size) 123 { 124 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 125 126 if (t == NULL) 127 return (ps_ops.ps_pread(P, addr, buf, size)); 128 129 if (mdb_tgt_vread(t, buf, size, addr) != size) 130 return (PS_BADADDR); 131 132 return (PS_OK); 133 } 134 135 /* 136 * Write to the specified target virtual address. 137 */ 138 ps_err_e 139 ps_pwrite(struct ps_prochandle *P, psaddr_t addr, const void *buf, size_t size) 140 { 141 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 142 143 if (t == NULL) 144 return (ps_ops.ps_pwrite(P, addr, buf, size)); 145 146 if (mdb_tgt_vwrite(t, buf, size, addr) != size) 147 return (PS_BADADDR); 148 149 return (PS_OK); 150 } 151 152 /* 153 * Search for a symbol by name and return the corresponding address. 154 */ 155 ps_err_e 156 ps_pglobal_lookup(struct ps_prochandle *P, const char *object, 157 const char *name, psaddr_t *symp) 158 { 159 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 160 GElf_Sym sym; 161 162 if (t == NULL) 163 return (ps_ops.ps_pglobal_lookup(P, object, name, symp)); 164 165 if (mdb_tgt_lookup_by_name(t, object, name, &sym, NULL) == 0) { 166 *symp = (psaddr_t)sym.st_value; 167 return (PS_OK); 168 } 169 170 return (PS_NOSYM); 171 } 172 173 /* 174 * Search for a symbol by name and return the corresponding symbol data. 175 * If we're compiled _LP64, we just call mdb_tgt_lookup_by_name and return 176 * because ps_sym_t is defined to be an Elf64_Sym, which is the same as a 177 * GElf_Sym. In the _ILP32 case, we have to convert mdb_tgt_lookup_by_name's 178 * result back to a ps_sym_t (which is an Elf32_Sym). 179 */ 180 ps_err_e 181 ps_pglobal_sym(struct ps_prochandle *P, const char *object, 182 const char *name, ps_sym_t *symp) 183 { 184 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 185 #if defined(_ILP32) 186 GElf_Sym sym; 187 188 if (t == NULL) 189 return (ps_ops.ps_pglobal_sym(P, object, name, symp)); 190 191 if (mdb_tgt_lookup_by_name(t, object, name, &sym, NULL) == 0) { 192 symp->st_name = (Elf32_Word)sym.st_name; 193 symp->st_value = (Elf32_Addr)sym.st_value; 194 symp->st_size = (Elf32_Word)sym.st_size; 195 symp->st_info = ELF32_ST_INFO( 196 GELF_ST_BIND(sym.st_info), GELF_ST_TYPE(sym.st_info)); 197 symp->st_other = sym.st_other; 198 symp->st_shndx = sym.st_shndx; 199 return (PS_OK); 200 } 201 202 #elif defined(_LP64) 203 if (t == NULL) 204 return (ps_ops.ps_pglobal_sym(P, object, name, symp)); 205 206 if (mdb_tgt_lookup_by_name(t, object, name, symp, NULL) == 0) 207 return (PS_OK); 208 #endif 209 210 return (PS_NOSYM); 211 } 212 213 /* 214 * Report a debug message. We allow proc_service API clients to report 215 * messages via our debug stream if the MDB_DBG_PSVC token is enabled. 216 */ 217 void 218 ps_plog(const char *format, ...) 219 { 220 va_list alist; 221 222 va_start(alist, format); 223 mdb_dvprintf(MDB_DBG_PSVC, format, alist); 224 va_end(alist); 225 } 226 227 /* 228 * Return the auxv structure from the process being examined. 229 */ 230 ps_err_e 231 ps_pauxv(struct ps_prochandle *P, const auxv_t **auxvp) 232 { 233 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 234 235 if (t == NULL) 236 return (ps_ops.ps_pauxv(P, auxvp)); 237 238 if (mdb_tgt_auxv(t, auxvp) != 0) 239 return (PS_ERR); 240 241 return (PS_OK); 242 } 243 244 ps_err_e 245 ps_pbrandname(struct ps_prochandle *P, char *buf, size_t len) 246 { 247 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 248 const auxv_t *auxv; 249 250 if (t == NULL) 251 return (ps_ops.ps_pbrandname(P, buf, len)); 252 253 if (mdb_tgt_auxv(t, &auxv) != 0) 254 return (PS_ERR); 255 256 while (auxv->a_type != AT_NULL) { 257 if (auxv->a_type == AT_SUN_BRANDNAME) 258 break; 259 auxv++; 260 } 261 if (auxv->a_type == AT_NULL) 262 return (PS_ERR); 263 264 if (mdb_tgt_readstr(t, MDB_TGT_AS_VIRT, 265 buf, len, auxv->a_un.a_val) <= 0) 266 return (PS_ERR); 267 268 return (PS_OK); 269 } 270 271 /* 272 * Return the data model of the target. 273 */ 274 ps_err_e 275 ps_pdmodel(struct ps_prochandle *P, int *dm) 276 { 277 mdb_tgt_t *t = mdb_tgt_from_pshandle(P); 278 279 if (t == NULL) 280 return (ps_ops.ps_pdmodel(P, dm)); 281 282 switch (mdb_tgt_dmodel(t)) { 283 case MDB_TGT_MODEL_LP64: 284 *dm = PR_MODEL_LP64; 285 return (PS_OK); 286 case MDB_TGT_MODEL_ILP32: 287 *dm = PR_MODEL_ILP32; 288 return (PS_OK); 289 } 290 291 return (PS_ERR); 292 } 293 294 /* 295 * Stub function in case we cannot find the necessary symbols from libproc. 296 */ 297 static ps_err_e 298 ps_fail(struct ps_prochandle *P) 299 { 300 mdb_dprintf(MDB_DBG_PSVC, "failing call to pshandle %p\n", (void *)P); 301 return (PS_BADPID); 302 } 303 304 /* 305 * Initialization function for the proc service interposition layer: we use 306 * libdl to look up the next definition of each function in the link map. 307 */ 308 void 309 mdb_pservice_init(void) 310 { 311 if ((ps_ops.ps_pread = (ps_err_e (*)()) 312 dlsym(RTLD_NEXT, "ps_pread")) == NULL) 313 ps_ops.ps_pread = (ps_err_e (*)())ps_fail; 314 315 if ((ps_ops.ps_pwrite = (ps_err_e (*)()) 316 dlsym(RTLD_NEXT, "ps_pwrite")) == NULL) 317 ps_ops.ps_pwrite = (ps_err_e (*)())ps_fail; 318 319 if ((ps_ops.ps_pglobal_lookup = (ps_err_e (*)()) 320 dlsym(RTLD_NEXT, "ps_pglobal_lookup")) == NULL) 321 ps_ops.ps_pglobal_lookup = (ps_err_e (*)())ps_fail; 322 323 if ((ps_ops.ps_pglobal_sym = (ps_err_e (*)()) 324 dlsym(RTLD_NEXT, "ps_pglobal_sym")) == NULL) 325 ps_ops.ps_pglobal_sym = (ps_err_e (*)())ps_fail; 326 327 if ((ps_ops.ps_pauxv = (ps_err_e (*)()) 328 dlsym(RTLD_NEXT, "ps_pauxv")) == NULL) 329 ps_ops.ps_pauxv = (ps_err_e (*)())ps_fail; 330 331 if ((ps_ops.ps_pbrandname = (ps_err_e (*)()) 332 dlsym(RTLD_NEXT, "ps_pbrandname")) == NULL) 333 ps_ops.ps_pbrandname = (ps_err_e (*)())ps_fail; 334 335 if ((ps_ops.ps_pdmodel = (ps_err_e (*)()) 336 dlsym(RTLD_NEXT, "ps_pdmodel")) == NULL) 337 ps_ops.ps_pdmodel = (ps_err_e (*)())ps_fail; 338 } 339