usr/src/cmd/sgs/rtld/amd64/_setup.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 2009 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26 /*
  27  * Copyright (c) 2018, Joyent, Inc.
  28  */
  29
  30 /*
  31  * amd64 specific setup routine  -  relocate ld.so's symbols, setup its
  32  * environment, map in loadable sections of the executable.
  33  *
  34  * Takes base address ld.so was loaded at, address of ld.so's dynamic
  35  * structure, address of process environment pointers, address of auxiliary
  36  * vector and * argv[0] (process name).
  37  * If errors occur, send process signal - otherwise
  38  * return executable's entry point to the bootstrap routine.
  39  */
  40
  41 #include        <signal.h>
  42 #include        <stdlib.h>
  43 #include        <sys/auxv.h>
  44 #include        <sys/types.h>
  45 #include        <sys/stat.h>
  46 #include        <link.h>
  47 #include        <dlfcn.h>
  48 #include        "_rtld.h"
  49 #include        "_audit.h"
  50 #include        "msg.h"
  51
  52 /*
  53  * Number of bytes to save for register usage.
  54  */
  55 uint_t _plt_save_size;
  56 void (*_plt_fp_save)(void *);
  57 void (*_plt_fp_restore)(void *);
  58
  59 extern void _elf_rtbndr_fp_save_orig(void *);
  60 extern void _elf_rtbndr_fp_restore_orig(void *);
  61 extern void _elf_rtbndr_fp_fxsave(void *);
  62 extern void _elf_rtbndr_fp_fxrestore(void *);
  63 extern void _elf_rtbndr_fp_xsave(void *);
  64 extern void _elf_rtbndr_fp_xrestore(void *);
  65
  66 /*
  67  * Based on what the kernel has told us, go through and set up the various
  68  * pointers that we'll need for elf_rtbndr for the FPU.
  69  */
  70 static void
  71 _setup_plt_fpu(int kind, size_t len)
  72 {
  73         /*
  74          * If we didn't get a length for some reason, fall back to the old
  75          * implementation.
  76          */
  77         if (len == 0)
  78                 kind = -1;
  79
  80         switch (kind) {
  81         case AT_386_FPINFO_FXSAVE:
  82                 _plt_fp_save = _elf_rtbndr_fp_fxsave;
  83                 _plt_fp_restore = _elf_rtbndr_fp_fxrestore;
  84                 _plt_save_size = len;
  85                 break;
  86         /*
  87          * We can treat processors that don't correctly handle the exception
  88          * information in xsave the same way we do others. The information
  89          * that may or may not be properly saved and restored should not be
  90          * relevant to us because of the ABI.
  91          */
  92         case AT_386_FPINFO_XSAVE:
  93         case AT_386_FPINFO_XSAVE_AMD:
  94                 _plt_fp_save = _elf_rtbndr_fp_xsave;
  95                 _plt_fp_restore = _elf_rtbndr_fp_xrestore;
  96                 _plt_save_size = len;
  97                 break;
  98         default:
  99                 _plt_fp_save = _elf_rtbndr_fp_save_orig;
 100                 _plt_fp_restore = _elf_rtbndr_fp_restore_orig;
 101                 /*
 102                  * The ABI says that 8 floating point registers are used for
 103                  * passing arguments (%xmm0 through %xmm7). Because these
 104                  * registers on some platforms may shadow the %ymm and %zmm
 105                  * registers, we end up needing to size this for the maximally
 106                  * sized register we care about, a 512-bit (64-byte) zmm
 107                  * register.
 108                  */
 109                 _plt_save_size = 64 * 8;
 110                 break;
 111         }
 112 }
 113
 114 /* VARARGS */
 115 unsigned long
 116 _setup(Boot *ebp, Dyn *ld_dyn)
 117 {
 118         ulong_t         reladdr, relacount, ld_base = 0;
 119         ulong_t         relaent = 0, pltrelsz = 0;
 120         ulong_t         strtab, soname, interp_base = 0;
 121         char            *_rt_name, **_envp, **_argv;
 122         int             _syspagsz = 0, fd = -1;
 123         uint_t          _flags = 0;
 124         uint_t          hwcap[2] = { 0, 0 };
 125         Dyn             *dyn_ptr;
 126         Phdr            *phdr = NULL;
 127         Rt_map          *lmp;
 128         auxv_t          *auxv, *_auxv;
 129         uid_t           uid = (uid_t)-1, euid = (uid_t)-1;
 130         gid_t           gid = (gid_t)-1, egid = (gid_t)-1;
 131         char            *_platform = NULL, *_execname = NULL, *_emulator = NULL;
 132         int             auxflags = -1, fpkind = -1;
 133         size_t          fpsize = 0;
 134
 135         /*
 136          * Scan the bootstrap structure to pick up the basics.
 137          */
 138         for (; ebp->eb_tag != EB_NULL; ebp++)
 139                 switch (ebp->eb_tag) {
 140                 case EB_LDSO_BASE:
 141                         ld_base = (unsigned long)ebp->eb_un.eb_val;
 142                         break;
 143                 case EB_ARGV:
 144                         _argv = (char **)ebp->eb_un.eb_ptr;
 145                         break;
 146                 case EB_ENVP:
 147                         _envp = (char **)ebp->eb_un.eb_ptr;
 148                         break;
 149                 case EB_AUXV:
 150                         _auxv = (auxv_t *)ebp->eb_un.eb_ptr;
 151                         break;
 152                 case EB_PAGESIZE:
 153                         _syspagsz = (int)ebp->eb_un.eb_val;
 154                         break;
 155                 }
 156
 157         /*
 158          * Search the aux. vector for the information passed by exec.
 159          */
 160         for (auxv = _auxv; auxv->a_type != AT_NULL; auxv++) {
 161                 switch (auxv->a_type) {
 162                 case AT_EXECFD:
 163                         /* this is the old exec that passes a file descriptor */
 164                         fd = (int)auxv->a_un.a_val;
 165                         break;
 166                 case AT_FLAGS:
 167                         /* processor flags (MAU available, etc) */
 168                         _flags = auxv->a_un.a_val;
 169                         break;
 170                 case AT_PAGESZ:
 171                         /* system page size */
 172                         _syspagsz = (int)auxv->a_un.a_val;
 173                         break;
 174                 case AT_PHDR:
 175                         /* address of the segment table */
 176                         phdr = (Phdr *)auxv->a_un.a_ptr;
 177                         break;
 178                 case AT_BASE:
 179                         /* interpreter base address */
 180                         if (ld_base == 0)
 181                                 ld_base = auxv->a_un.a_val;
 182                         interp_base = auxv->a_un.a_val;
 183                         break;
 184                 case AT_SUN_UID:
 185                         /* effective user id for the executable */
 186                         euid = (uid_t)auxv->a_un.a_val;
 187                         break;
 188                 case AT_SUN_RUID:
 189                         /* real user id for the executable */
 190                         uid = (uid_t)auxv->a_un.a_val;
 191                         break;
 192                 case AT_SUN_GID:
 193                         /* effective group id for the executable */
 194                         egid = (gid_t)auxv->a_un.a_val;
 195                         break;
 196                 case AT_SUN_RGID:
 197                         /* real group id for the executable */
 198                         gid = (gid_t)auxv->a_un.a_val;
 199                         break;
 200                 case AT_SUN_PLATFORM:
 201                         /* platform name */
 202                         _platform = auxv->a_un.a_ptr;
 203                         break;
 204                 case AT_SUN_EXECNAME:
 205                         /* full pathname of execed object */
 206                         _execname = auxv->a_un.a_ptr;
 207                         break;
 208                 case AT_SUN_AUXFLAGS:
 209                         /* auxiliary flags */
 210                         auxflags = (int)auxv->a_un.a_val;
 211                         break;
 212                 case AT_SUN_HWCAP:
 213                         /* hardware capabilities */
 214                         hwcap[0] = (uint_t)auxv->a_un.a_val;
 215                         break;
 216                 case AT_SUN_HWCAP2:
 217                         /* hardware capabilities */
 218                         hwcap[1] = (uint_t)auxv->a_un.a_val;
 219                         break;
 220                 case AT_SUN_EMULATOR:
 221                         /* name of emulation library, if any */
 222                         _emulator = auxv->a_un.a_ptr;
 223                         break;
 224                 case AT_SUN_FPTYPE:
 225                         fpkind = (int)auxv->a_un.a_val;
 226                         break;
 227                 case AT_SUN_FPSIZE:
 228                         fpsize = (size_t)auxv->a_un.a_val;
 229                         break;
 230                 }
 231         }
 232
 233         /*
 234          * Get needed info from ld.so's dynamic structure.
 235          */
 236         /* LINTED */
 237         dyn_ptr = (Dyn *)((char *)ld_dyn + ld_base);
 238         for (ld_dyn = dyn_ptr; ld_dyn->d_tag != DT_NULL; ld_dyn++) {
 239                 switch (ld_dyn->d_tag) {
 240                 case DT_RELA:
 241                         reladdr = ld_dyn->d_un.d_ptr + ld_base;
 242                         break;
 243                 case DT_RELACOUNT:
 244                         relacount = ld_dyn->d_un.d_val;
 245                         break;
 246                 case DT_RELAENT:
 247                         relaent = ld_dyn->d_un.d_val;
 248                         break;
 249                 case DT_PLTRELSZ:
 250                         pltrelsz = ld_dyn->d_un.d_val;
 251                         break;
 252                 case DT_STRTAB:
 253                         strtab = ld_dyn->d_un.d_ptr + ld_base;
 254                         break;
 255                 case DT_SONAME:
 256                         soname = ld_dyn->d_un.d_val;
 257                         break;
 258                 }
 259         }
 260         _rt_name = (char *)strtab + soname;
 261
 262         /*
 263          * If we don't have a RELAENT, just assume the size.
 264          */
 265         if (relaent == 0)
 266                 relaent = sizeof (Rela);
 267
 268         /*
 269          * As all global symbol references within ld.so.1 are protected
 270          * (symbolic), only RELATIVE and JMPSLOT relocations should be left
 271          * to process at runtime.  Process all relocations now.
 272          */
 273         relacount += (pltrelsz / relaent);
 274         for (; relacount; relacount--) {
 275                 ulong_t roffset;
 276
 277                 roffset = ((Rela *)reladdr)->r_offset + ld_base;
 278                 *((ulong_t *)roffset) += ld_base +
 279                     ((Rela *)reladdr)->r_addend;
 280                 reladdr += relaent;
 281         }
 282
 283         /*
 284          * If an emulation library is being used, use that as the linker's
 285          * effective executable name. The real executable is not linked by this
 286          * linker.
 287          */
 288         if (_emulator != NULL) {
 289                 _execname = _emulator;
 290                 rtld_flags2 |= RT_FL2_BRANDED;
 291         }
 292
 293         /*
 294          * Initialize the dyn_plt_ent_size field.  It currently contains the
 295          * size of the dyn_plt_template.  It still needs to be aligned and have
 296          * space for the 'dyn_data' area added.
 297          */
 298         dyn_plt_ent_size = ROUND(dyn_plt_ent_size, M_WORD_ALIGN) +
 299             sizeof (uintptr_t) + sizeof (uintptr_t) + sizeof (ulong_t) +
 300             sizeof (ulong_t) + sizeof (Sym);
 301
 302         /*
 303          * Initialize the amd64 specific PLT relocation constants based on the
 304          * FP information that we have.
 305          */
 306         _setup_plt_fpu(fpkind, fpsize);
 307
 308         /*
 309          * Continue with generic startup processing.
 310          */
 311         if ((lmp = setup((char **)_envp, (auxv_t *)_auxv, _flags, _platform,
 312             _syspagsz, _rt_name, ld_base, interp_base, fd, phdr,
 313             _execname, _argv, uid, euid, gid, egid, NULL, auxflags,
 314             hwcap)) == NULL) {
 315                 rtldexit(&lml_main, 1);
 316         }
 317
 318         return (LM_ENTRY_PT(lmp)());
 319 }