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, Addr *value_p, 66 Elf64_Sxword *addend_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 *addend_p = 0; 73 ((tnf_probe_control_t *)offset)->next = *probelist; 74 *probelist = (tnf_probe_control_t *)offset; 75 return (0); 76 } 77 if (strcmp(symname, TAG_MARKER_SYMBOL) == 0) { 78 *addend_p = 0; 79 *value_p = (Addr)*taglist; 80 *taglist = (tnf_tag_data_t *)offset; 81 return (0); 82 } 83 return (1); 84 } 85 86 #define SDT_NOP 0x90 87 #define SDT_NOPS 5 88 89 static int 90 sdt_reloc_resolve(struct module *mp, char *symname, uint8_t *instr) 91 { 92 sdt_probedesc_t *sdp; 93 int i; 94 95 /* 96 * The "statically defined tracing" (SDT) provider for DTrace uses 97 * a mechanism similar to TNF, but somewhat simpler. (Surprise, 98 * surprise.) The SDT mechanism works by replacing calls to the 99 * undefined routine __dtrace_probe_[name] with nop instructions. 100 * The relocations are logged, and SDT itself will later patch the 101 * running binary appropriately. 102 */ 103 if (strncmp(symname, sdt_prefix, strlen(sdt_prefix)) != 0) 104 return (1); 105 106 symname += strlen(sdt_prefix); 107 108 sdp = kobj_alloc(sizeof (sdt_probedesc_t), KM_WAIT); 109 sdp->sdpd_name = kobj_alloc(strlen(symname) + 1, KM_WAIT); 110 bcopy(symname, sdp->sdpd_name, strlen(symname) + 1); 111 112 sdp->sdpd_offset = (uintptr_t)instr; 113 sdp->sdpd_next = mp->sdt_probes; 114 mp->sdt_probes = sdp; 115 116 for (i = 0; i < SDT_NOPS; i++) 117 instr[i - 1] = SDT_NOP; 118 119 return (0); 120 } 121 122 int 123 /* ARGSUSED2 */ 124 do_relocate(struct module *mp, char *reltbl, Word relshtype, int nreloc, 125 int relocsize, Addr baseaddr) 126 { 127 unsigned long stndx; 128 unsigned long off; /* can't be register for tnf_reloc_resolve() */ 129 register unsigned long reladdr, rend; 130 register unsigned int rtype; 131 unsigned long value; 132 Elf64_Sxword addend; 133 Sym *symref; 134 int err = 0; 135 tnf_probe_control_t *probelist = NULL; 136 tnf_tag_data_t *taglist = NULL; 137 int symnum; 138 reladdr = (unsigned long)reltbl; 139 rend = reladdr + nreloc * relocsize; 140 141 #ifdef KOBJ_DEBUG 142 if (kobj_debug & D_RELOCATIONS) { 143 _kobj_printf(ops, "krtld:\ttype\t\t\toffset\t addend" 144 " symbol\n"); 145 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n"); 146 } 147 #endif 148 149 symnum = -1; 150 /* loop through relocations */ 151 while (reladdr < rend) { 152 symnum++; 153 rtype = ELF_R_TYPE(((Rela *)reladdr)->r_info); 154 off = ((Rela *)reladdr)->r_offset; 155 stndx = ELF_R_SYM(((Rela *)reladdr)->r_info); 156 if (stndx >= mp->nsyms) { 157 _kobj_printf(ops, "do_relocate: bad strndx %d\n", 158 symnum); 159 return (-1); 160 } 161 if ((rtype > R_AMD64_NUM) || IS_TLS_INS(rtype)) { 162 _kobj_printf(ops, "krtld: invalid relocation type %d", 163 rtype); 164 _kobj_printf(ops, " at 0x%llx:", off); 165 _kobj_printf(ops, " file=%s\n", mp->filename); 166 err = 1; 167 continue; 168 } 169 170 171 addend = (long)(((Rela *)reladdr)->r_addend); 172 reladdr += relocsize; 173 174 175 if (rtype == R_AMD64_NONE) 176 continue; 177 178 #ifdef KOBJ_DEBUG 179 if (kobj_debug & D_RELOCATIONS) { 180 Sym * symp; 181 symp = (Sym *) 182 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 183 _kobj_printf(ops, "krtld:\t%s", 184 conv_reloc_amd64_type(rtype)); 185 _kobj_printf(ops, "\t0x%8llx", off); 186 _kobj_printf(ops, " 0x%8llx", addend); 187 _kobj_printf(ops, " %s\n", 188 (const char *)mp->strings + symp->st_name); 189 } 190 #endif 191 192 if (!(mp->flags & KOBJ_EXEC)) 193 off += baseaddr; 194 195 /* 196 * if R_AMD64_RELATIVE, simply add base addr 197 * to reloc location 198 */ 199 200 if (rtype == R_AMD64_RELATIVE) { 201 value = baseaddr; 202 } else { 203 /* 204 * get symbol table entry - if symbol is local 205 * value is base address of this object 206 */ 207 symref = (Sym *) 208 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 209 210 if (ELF_ST_BIND(symref->st_info) == STB_LOCAL) { 211 /* *** this is different for .o and .so */ 212 value = symref->st_value; 213 } else { 214 /* 215 * It's global. Allow weak references. If 216 * the symbol is undefined, give TNF (the 217 * kernel probes facility) a chance to see 218 * if it's a probe site, and fix it up if so. 219 */ 220 if (symref->st_shndx == SHN_UNDEF && 221 sdt_reloc_resolve(mp, mp->strings + 222 symref->st_name, (uint8_t *)off) == 0) 223 continue; 224 225 if (symref->st_shndx == SHN_UNDEF && 226 tnf_reloc_resolve(mp->strings + 227 symref->st_name, &symref->st_value, 228 &addend, off, &probelist, &taglist) != 0) { 229 if (ELF_ST_BIND(symref->st_info) 230 != STB_WEAK) { 231 _kobj_printf(ops, 232 "not found: %s\n", 233 mp->strings + 234 symref->st_name); 235 err = 1; 236 } 237 continue; 238 } else { /* symbol found - relocate */ 239 /* 240 * calculate location of definition 241 * - symbol value plus base address of 242 * containing shared object 243 */ 244 value = symref->st_value; 245 246 } /* end else symbol found */ 247 } /* end global or weak */ 248 } /* end not R_AMD64_RELATIVE */ 249 250 value += addend; 251 /* 252 * calculate final value - 253 * if PC-relative, subtract ref addr 254 */ 255 if (IS_PC_RELATIVE(rtype)) 256 value -= off; 257 258 #ifdef KOBJ_DEBUG 259 if (kobj_debug & D_RELOCATIONS) { 260 _kobj_printf(ops, "krtld:\t\t\t\t0x%8llx", off); 261 _kobj_printf(ops, " 0x%8llx\n", value); 262 } 263 #endif 264 265 if (do_reloc_krtld(rtype, (unsigned char *)off, &value, 266 (const char *)mp->strings + symref->st_name, 267 mp->filename) == 0) 268 err = 1; 269 270 } /* end of while loop */ 271 if (err) 272 return (-1); 273 274 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist)) 275 mp->flags |= KOBJ_TNF_PROBE; 276 277 return (0); 278 } 279 280 int 281 do_relocations(struct module *mp) 282 { 283 uint_t shn; 284 Shdr *shp, *rshp; 285 uint_t nreloc; 286 287 /* do the relocations */ 288 for (shn = 1; shn < mp->hdr.e_shnum; shn++) { 289 rshp = (Shdr *) 290 (mp->shdrs + shn * mp->hdr.e_shentsize); 291 if (rshp->sh_type == SHT_REL) { 292 _kobj_printf(ops, "%s can't process type SHT_REL\n", 293 mp->filename); 294 return (-1); 295 } 296 if (rshp->sh_type != SHT_RELA) 297 continue; 298 if (rshp->sh_link != mp->symtbl_section) { 299 _kobj_printf(ops, "%s reloc for non-default symtab\n", 300 mp->filename); 301 return (-1); 302 } 303 if (rshp->sh_info >= mp->hdr.e_shnum) { 304 _kobj_printf(ops, "do_relocations: %s sh_info ", 305 mp->filename); 306 _kobj_printf(ops, "out of range %d\n", shn); 307 goto bad; 308 } 309 nreloc = rshp->sh_size / rshp->sh_entsize; 310 311 /* get the section header that this reloc table refers to */ 312 shp = (Shdr *) 313 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize); 314 315 /* 316 * Do not relocate any section that isn't loaded into memory. 317 * Most commonly this will skip over the .rela.stab* sections 318 */ 319 if (!(shp->sh_flags & SHF_ALLOC)) 320 continue; 321 #ifdef KOBJ_DEBUG 322 if (kobj_debug & D_RELOCATIONS) { 323 _kobj_printf(ops, "krtld: relocating: file=%s ", 324 mp->filename); 325 _kobj_printf(ops, "section=%d\n", shn); 326 } 327 #endif 328 329 if (do_relocate(mp, (char *)rshp->sh_addr, rshp->sh_type, 330 nreloc, rshp->sh_entsize, shp->sh_addr) < 0) { 331 _kobj_printf(ops, 332 "do_relocations: %s do_relocate failed\n", 333 mp->filename); 334 goto bad; 335 } 336 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 337 rshp->sh_addr = 0; 338 } 339 mp->flags |= KOBJ_RELOCATED; 340 return (0); 341 bad: 342 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 343 rshp->sh_addr = 0; 344 return (-1); 345 } 346