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 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * x86 relocation code. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/sysmacros.h> 36 #include <sys/systm.h> 37 #include <sys/user.h> 38 #include <sys/bootconf.h> 39 #include <sys/modctl.h> 40 #include <sys/elf.h> 41 #include <sys/kobj.h> 42 #include <sys/kobj_impl.h> 43 #include <sys/tnf.h> 44 #include <sys/tnf_probe.h> 45 46 #include "reloc.h" 47 48 49 /* 50 * Probe Discovery 51 */ 52 53 #define PROBE_MARKER_SYMBOL "__tnf_probe_version_1" 54 #define TAG_MARKER_SYMBOL "__tnf_tag_version_1" 55 56 extern int tnf_splice_probes(int, tnf_probe_control_t *, tnf_tag_data_t *); 57 58 /* 59 * The kernel run-time linker calls this to try to resolve a reference 60 * it can't otherwise resolve. We see if it's marking a probe control 61 * block; if so, we do the resolution and return 0. If not, we return 62 * 1 to show that we can't resolve it, either. 63 */ 64 static int 65 tnf_reloc_resolve(char *symname, 66 Addr *value_p, 67 long offset, 68 tnf_probe_control_t **probelist, 69 tnf_tag_data_t **taglist) 70 { 71 if (strcmp(symname, PROBE_MARKER_SYMBOL) == 0) { 72 ((tnf_probe_control_t *)offset)->next = *probelist; 73 *probelist = (tnf_probe_control_t *)offset; 74 return (0); 75 } 76 if (strcmp(symname, TAG_MARKER_SYMBOL) == 0) { 77 *value_p = (Addr)*taglist; 78 *taglist = (tnf_tag_data_t *)offset; 79 return (0); 80 } 81 return (1); 82 } 83 84 #define SDT_NOP 0x90 85 #define SDT_NOPS 5 86 87 static int 88 sdt_reloc_resolve(struct module *mp, char *symname, uint8_t *instr) 89 { 90 sdt_probedesc_t *sdp; 91 int i; 92 93 /* 94 * The "statically defined tracing" (SDT) provider for DTrace uses 95 * a mechanism similar to TNF, but somewhat simpler. (Surprise, 96 * surprise.) The SDT mechanism works by replacing calls to the 97 * undefined routine __dtrace_probe_[name] with nop instructions. 98 * The relocations are logged, and SDT itself will later patch the 99 * running binary appropriately. 100 */ 101 if (strncmp(symname, sdt_prefix, strlen(sdt_prefix)) != 0) 102 return (1); 103 104 symname += strlen(sdt_prefix); 105 106 sdp = kobj_alloc(sizeof (sdt_probedesc_t), KM_WAIT); 107 sdp->sdpd_name = kobj_alloc(strlen(symname) + 1, KM_WAIT); 108 bcopy(symname, sdp->sdpd_name, strlen(symname) + 1); 109 110 sdp->sdpd_offset = (uintptr_t)instr; 111 sdp->sdpd_next = mp->sdt_probes; 112 mp->sdt_probes = sdp; 113 114 for (i = 0; i < SDT_NOPS; i++) 115 instr[i - 1] = SDT_NOP; 116 117 return (0); 118 } 119 120 int 121 /* ARGSUSED2 */ 122 do_relocate(struct module *mp, char *reltbl, Word relshtype, int nreloc, 123 int relocsize, Addr baseaddr) 124 { 125 unsigned long stndx; 126 unsigned long off; /* can't be register for tnf_reloc_resolve() */ 127 register unsigned long reladdr, rend; 128 register unsigned int rtype; 129 long value; 130 Sym *symref; 131 int err = 0; 132 tnf_probe_control_t *probelist = NULL; 133 tnf_tag_data_t *taglist = NULL; 134 int symnum; 135 136 reladdr = (unsigned long)reltbl; 137 rend = reladdr + nreloc * relocsize; 138 139 #ifdef KOBJ_DEBUG 140 if (kobj_debug & D_RELOCATIONS) { 141 _kobj_printf(ops, "krtld:\ttype\t\t\toffset symbol\n"); 142 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n"); 143 } 144 #endif 145 146 symnum = -1; 147 /* loop through relocations */ 148 while (reladdr < rend) { 149 symnum++; 150 rtype = ELF32_R_TYPE(((Rel *)reladdr)->r_info); 151 off = ((Rel *)reladdr)->r_offset; 152 stndx = ELF32_R_SYM(((Rel *)reladdr)->r_info); 153 if (stndx >= mp->nsyms) { 154 _kobj_printf(ops, "do_relocate: bad strndx %d\n", 155 symnum); 156 return (-1); 157 } 158 if ((rtype > R_386_NUM) || IS_TLS_INS(rtype)) { 159 _kobj_printf(ops, "krtld: invalid relocation type %d", 160 rtype); 161 _kobj_printf(ops, " at 0x%llx:", off); 162 _kobj_printf(ops, " file=%s\n", mp->filename); 163 err = 1; 164 continue; 165 } 166 167 168 reladdr += relocsize; 169 170 171 if (rtype == R_386_NONE) 172 continue; 173 174 #ifdef KOBJ_DEBUG 175 if (kobj_debug & D_RELOCATIONS) { 176 Sym * symp; 177 symp = (Sym *) 178 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 179 _kobj_printf(ops, "krtld:\t%s", 180 conv_reloc_386_type(rtype)); 181 _kobj_printf(ops, "\t0x%8x", off); 182 _kobj_printf(ops, " %s\n", 183 (const char *)mp->strings + symp->st_name); 184 } 185 #endif 186 187 if (!(mp->flags & KOBJ_EXEC)) 188 off += baseaddr; 189 190 /* 191 * if R_386_RELATIVE, simply add base addr 192 * to reloc location 193 */ 194 195 if (rtype == R_386_RELATIVE) { 196 value = baseaddr; 197 } else { 198 /* 199 * get symbol table entry - if symbol is local 200 * value is base address of this object 201 */ 202 symref = (Sym *) 203 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 204 205 if (ELF32_ST_BIND(symref->st_info) == STB_LOCAL) { 206 /* *** this is different for .o and .so */ 207 value = symref->st_value; 208 } else { 209 /* 210 * It's global. Allow weak references. If 211 * the symbol is undefined, give TNF (the 212 * kernel probes facility) a chance to see 213 * if it's a probe site, and fix it up if so. 214 */ 215 if (symref->st_shndx == SHN_UNDEF && 216 sdt_reloc_resolve(mp, mp->strings + 217 symref->st_name, (uint8_t *)off) == 0) 218 continue; 219 220 if (symref->st_shndx == SHN_UNDEF && 221 tnf_reloc_resolve(mp->strings + 222 symref->st_name, &symref->st_value, 223 off, &probelist, &taglist) != 0) { 224 if (ELF32_ST_BIND(symref->st_info) 225 != STB_WEAK) { 226 _kobj_printf(ops, 227 "not found: %s\n", 228 mp->strings + 229 symref->st_name); 230 err = 1; 231 } 232 continue; 233 } else { /* symbol found - relocate */ 234 /* 235 * calculate location of definition 236 * - symbol value plus base address of 237 * containing shared object 238 */ 239 value = symref->st_value; 240 241 } /* end else symbol found */ 242 } /* end global or weak */ 243 } /* end not R_386_RELATIVE */ 244 245 /* 246 * calculate final value - 247 * if PC-relative, subtract ref addr 248 */ 249 if (IS_PC_RELATIVE(rtype)) 250 value -= off; 251 252 #ifdef KOBJ_DEBUG 253 if (kobj_debug & D_RELOCATIONS) { 254 _kobj_printf(ops, "krtld:\t\t\t\t0x%8x", off); 255 _kobj_printf(ops, " 0x%8x\n", value); 256 } 257 #endif 258 259 if (do_reloc_krtld(rtype, (unsigned char *)off, (Word *)&value, 260 (const char *)mp->strings + symref->st_name, 261 mp->filename) == 0) 262 err = 1; 263 264 } /* end of while loop */ 265 if (err) 266 return (-1); 267 268 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist)) 269 mp->flags |= KOBJ_TNF_PROBE; 270 271 return (0); 272 } 273 274 int 275 do_relocations(struct module *mp) 276 { 277 uint_t shn; 278 Shdr *shp, *rshp; 279 uint_t nreloc; 280 281 /* do the relocations */ 282 for (shn = 1; shn < mp->hdr.e_shnum; shn++) { 283 rshp = (Shdr *) 284 (mp->shdrs + shn * mp->hdr.e_shentsize); 285 if (rshp->sh_type == SHT_RELA) { 286 _kobj_printf(ops, "%s can't process type SHT_RELA\n", 287 mp->filename); 288 return (-1); 289 } 290 if (rshp->sh_type != SHT_REL) 291 continue; 292 if (rshp->sh_link != mp->symtbl_section) { 293 _kobj_printf(ops, "%s reloc for non-default symtab\n", 294 mp->filename); 295 return (-1); 296 } 297 if (rshp->sh_info >= mp->hdr.e_shnum) { 298 _kobj_printf(ops, "do_relocations: %s sh_info ", 299 mp->filename); 300 _kobj_printf(ops, "out of range %d\n", shn); 301 goto bad; 302 } 303 nreloc = rshp->sh_size / rshp->sh_entsize; 304 305 /* get the section header that this reloc table refers to */ 306 shp = (Shdr *) 307 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize); 308 309 /* 310 * Do not relocate any section that isn't loaded into memory. 311 * Most commonly this will skip over the .rela.stab* sections 312 */ 313 if (!(shp->sh_flags & SHF_ALLOC)) 314 continue; 315 #ifdef KOBJ_DEBUG 316 if (kobj_debug & D_RELOCATIONS) { 317 _kobj_printf(ops, "krtld: relocating: file=%s ", 318 mp->filename); 319 _kobj_printf(ops, "section=%d\n", shn); 320 } 321 #endif 322 323 if (do_relocate(mp, (char *)rshp->sh_addr, rshp->sh_type, 324 nreloc, rshp->sh_entsize, shp->sh_addr) < 0) { 325 _kobj_printf(ops, 326 "do_relocations: %s do_relocate failed\n", 327 mp->filename); 328 goto bad; 329 } 330 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 331 rshp->sh_addr = 0; 332 } 333 mp->flags |= KOBJ_RELOCATED; 334 return (0); 335 bad: 336 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 337 rshp->sh_addr = 0; 338 return (-1); 339 } 340