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 * Copyright 2020 Joyent, Inc. 27 */ 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 do_relocate(struct module *mp, char *reltbl, int nreloc, int relocsize, 124 Addr baseaddr) 125 { 126 unsigned long stndx; 127 unsigned long off; /* can't be register for tnf_reloc_resolve() */ 128 register unsigned long reladdr, rend; 129 register unsigned int rtype; 130 unsigned long value; 131 Elf64_Sxword addend; 132 Sym *symref = NULL; 133 int err = 0; 134 tnf_probe_control_t *probelist = NULL; 135 tnf_tag_data_t *taglist = NULL; 136 int symnum; 137 reladdr = (unsigned long)reltbl; 138 rend = reladdr + nreloc * relocsize; 139 140 #ifdef KOBJ_DEBUG 141 if (kobj_debug & D_RELOCATIONS) { 142 _kobj_printf(ops, "krtld:\ttype\t\t\toffset\t addend" 143 " symbol\n"); 144 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n"); 145 } 146 #endif 147 148 symnum = -1; 149 /* loop through relocations */ 150 while (reladdr < rend) { 151 symnum++; 152 rtype = ELF_R_TYPE(((Rela *)reladdr)->r_info); 153 off = ((Rela *)reladdr)->r_offset; 154 stndx = ELF_R_SYM(((Rela *)reladdr)->r_info); 155 if (stndx >= mp->nsyms) { 156 _kobj_printf(ops, "do_relocate: bad strndx %d\n", 157 symnum); 158 return (-1); 159 } 160 if ((rtype > R_AMD64_NUM) || IS_TLS_INS(rtype)) { 161 _kobj_printf(ops, "krtld: invalid relocation type %d", 162 rtype); 163 _kobj_printf(ops, " at 0x%lx:", off); 164 _kobj_printf(ops, " file=%s\n", mp->filename); 165 err = 1; 166 continue; 167 } 168 169 170 addend = (long)(((Rela *)reladdr)->r_addend); 171 reladdr += relocsize; 172 173 174 if (rtype == R_AMD64_NONE) 175 continue; 176 177 #ifdef KOBJ_DEBUG 178 if (kobj_debug & D_RELOCATIONS) { 179 Sym * symp; 180 symp = (Sym *) 181 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 182 _kobj_printf(ops, "krtld:\t%s", 183 conv_reloc_amd64_type(rtype)); 184 _kobj_printf(ops, "\t0x%8lx", off); 185 _kobj_printf(ops, " %8lld", (longlong_t)addend); 186 _kobj_printf(ops, " %s\n", 187 (const char *)mp->strings + symp->st_name); 188 } 189 #endif 190 191 if (!(mp->flags & KOBJ_EXEC)) 192 off += baseaddr; 193 194 /* 195 * if R_AMD64_RELATIVE, simply add base addr 196 * to reloc location 197 */ 198 199 if (rtype == R_AMD64_RELATIVE) { 200 value = baseaddr; 201 } else { 202 /* 203 * get symbol table entry - if symbol is local 204 * value is base address of this object 205 */ 206 symref = (Sym *) 207 (mp->symtbl+(stndx * mp->symhdr->sh_entsize)); 208 209 if (ELF_ST_BIND(symref->st_info) == STB_LOCAL) { 210 /* *** this is different for .o and .so */ 211 value = symref->st_value; 212 } else { 213 /* 214 * It's global. Allow weak references. If 215 * the symbol is undefined, give TNF (the 216 * kernel probes facility) a chance to see 217 * if it's a probe site, and fix it up if so. 218 */ 219 if (symref->st_shndx == SHN_UNDEF && 220 sdt_reloc_resolve(mp, mp->strings + 221 symref->st_name, (uint8_t *)off) == 0) 222 continue; 223 224 if (symref->st_shndx == SHN_UNDEF && 225 tnf_reloc_resolve(mp->strings + 226 symref->st_name, &symref->st_value, 227 &addend, off, &probelist, &taglist) != 0) { 228 if (ELF_ST_BIND(symref->st_info) 229 != STB_WEAK) { 230 _kobj_printf(ops, 231 "not found: %s\n", 232 mp->strings + 233 symref->st_name); 234 err = 1; 235 } 236 continue; 237 } else { /* symbol found - relocate */ 238 /* 239 * calculate location of definition 240 * - symbol value plus base address of 241 * containing shared object 242 */ 243 value = symref->st_value; 244 245 } /* end else symbol found */ 246 } /* end global or weak */ 247 } /* end not R_AMD64_RELATIVE */ 248 249 value += addend; 250 /* 251 * calculate final value - 252 * if PC-relative, subtract ref addr 253 */ 254 if (IS_PC_RELATIVE(rtype)) 255 value -= off; 256 257 #ifdef KOBJ_DEBUG 258 if (kobj_debug & D_RELOCATIONS) { 259 _kobj_printf(ops, "krtld:\t\t\t\t0x%8lx", off); 260 _kobj_printf(ops, " 0x%8lx\n", value); 261 } 262 #endif 263 264 if (do_reloc_krtld(rtype, (unsigned char *)off, &value, 265 (const char *)mp->strings + symref->st_name, 266 mp->filename) == 0) 267 err = 1; 268 269 } /* end of while loop */ 270 if (err) 271 return (-1); 272 273 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist)) 274 mp->flags |= KOBJ_TNF_PROBE; 275 276 return (0); 277 } 278 279 int 280 do_relocations(struct module *mp) 281 { 282 uint_t shn; 283 Shdr *shp, *rshp; 284 uint_t nreloc; 285 286 /* do the relocations */ 287 for (shn = 1; shn < mp->hdr.e_shnum; shn++) { 288 rshp = (Shdr *) 289 (mp->shdrs + shn * mp->hdr.e_shentsize); 290 if (rshp->sh_type == SHT_REL) { 291 _kobj_printf(ops, "%s can't process type SHT_REL\n", 292 mp->filename); 293 return (-1); 294 } 295 if (rshp->sh_type != SHT_RELA) 296 continue; 297 if (rshp->sh_link != mp->symtbl_section) { 298 _kobj_printf(ops, "%s reloc for non-default symtab\n", 299 mp->filename); 300 return (-1); 301 } 302 if (rshp->sh_info >= mp->hdr.e_shnum) { 303 _kobj_printf(ops, "do_relocations: %s sh_info ", 304 mp->filename); 305 _kobj_printf(ops, "out of range %d\n", shn); 306 goto bad; 307 } 308 nreloc = rshp->sh_size / rshp->sh_entsize; 309 310 /* get the section header that this reloc table refers to */ 311 shp = (Shdr *) 312 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize); 313 314 /* 315 * Do not relocate any section that isn't loaded into memory. 316 * Most commonly this will skip over the .rela.stab* sections 317 */ 318 if (!(shp->sh_flags & SHF_ALLOC)) 319 continue; 320 #ifdef KOBJ_DEBUG 321 if (kobj_debug & D_RELOCATIONS) { 322 _kobj_printf(ops, "krtld: relocating: file=%s ", 323 mp->filename); 324 _kobj_printf(ops, "section=%d\n", shn); 325 } 326 #endif 327 328 if (do_relocate(mp, (char *)rshp->sh_addr, nreloc, 329 rshp->sh_entsize, shp->sh_addr) < 0) { 330 _kobj_printf(ops, 331 "do_relocations: %s do_relocate failed\n", 332 mp->filename); 333 goto bad; 334 } 335 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 336 rshp->sh_addr = 0; 337 } 338 mp->flags |= KOBJ_RELOCATED; 339 return (0); 340 bad: 341 kobj_free((void *)rshp->sh_addr, rshp->sh_size); 342 rshp->sh_addr = 0; 343 return (-1); 344 } 345