arch/x86/kernel/krtld/32/kobj_reloc.c

   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 <krtld/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 }