The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ctf.c

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    1 /*-
    2  * Copyright (c) 2008 John Birrell <jb@freebsd.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: stable/10/sys/kern/kern_ctf.c 279196 2015-02-23 01:24:10Z markj $
   27  */
   28 
   29 /*
   30  * Note this file is included by both link_elf.c and link_elf_obj.c.
   31  *
   32  * The CTF header structure definition can't be used here because it's
   33  * (annoyingly) covered by the CDDL. We will just use a few bytes from
   34  * it as an integer array where we 'know' what they mean.
   35  */
   36 #define CTF_HDR_SIZE            36
   37 #define CTF_HDR_STRTAB_U32      7
   38 #define CTF_HDR_STRLEN_U32      8
   39 
   40 #ifdef DDB_CTF
   41 static void *
   42 z_alloc(void *nil, u_int items, u_int size)
   43 {
   44         void *ptr;
   45 
   46         ptr = malloc(items * size, M_TEMP, M_NOWAIT);
   47         return ptr;
   48 }
   49 
   50 static void
   51 z_free(void *nil, void *ptr)
   52 {
   53         free(ptr, M_TEMP);
   54 }
   55 
   56 #endif
   57 
   58 static int
   59 link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
   60 {
   61 #ifdef DDB_CTF
   62         Elf_Ehdr *hdr = NULL;
   63         Elf_Shdr *shdr = NULL;
   64         caddr_t ctftab = NULL;
   65         caddr_t raw = NULL;
   66         caddr_t shstrtab = NULL;
   67         elf_file_t ef = (elf_file_t) lf;
   68         int flags;
   69         int i;
   70         int nbytes;
   71         size_t sz;
   72         struct nameidata nd;
   73         struct thread *td = curthread;
   74         uint8_t ctf_hdr[CTF_HDR_SIZE];
   75 #endif
   76         int error = 0;
   77 
   78         if (lf == NULL || lc == NULL)
   79                 return (EINVAL);
   80 
   81         /* Set the defaults for no CTF present. That's not a crime! */
   82         bzero(lc, sizeof(*lc));
   83 
   84 #ifdef DDB_CTF
   85         /*
   86          * First check if we've tried to load CTF data previously and the
   87          * CTF ELF section wasn't found. We flag that condition by setting
   88          * ctfcnt to -1. See below.
   89          */
   90         if (ef->ctfcnt < 0)
   91                 return (EFTYPE);
   92 
   93         /* Now check if we've already loaded the CTF data.. */
   94         if (ef->ctfcnt > 0) {
   95                 /* We only need to load once. */
   96                 lc->ctftab = ef->ctftab;
   97                 lc->ctfcnt = ef->ctfcnt;
   98                 lc->symtab = ef->ddbsymtab;
   99                 lc->strtab = ef->ddbstrtab;
  100                 lc->strcnt = ef->ddbstrcnt;
  101                 lc->nsym   = ef->ddbsymcnt;
  102                 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
  103                 lc->typoffp = (uint32_t **) &ef->typoff;
  104                 lc->typlenp = &ef->typlen;
  105                 return (0);
  106         }
  107 
  108         /*
  109          * We need to try reading the CTF data. Flag no CTF data present
  110          * by default and if we actually succeed in reading it, we'll
  111          * update ctfcnt to the number of bytes read.
  112          */
  113         ef->ctfcnt = -1;
  114 
  115         NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, lf->pathname, td);
  116         flags = FREAD;
  117         error = vn_open(&nd, &flags, 0, NULL);
  118         if (error)
  119                 return (error);
  120         NDFREE(&nd, NDF_ONLY_PNBUF);
  121 
  122         /* Allocate memory for the FLF header. */
  123         hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
  124 
  125         /* Read the ELF header. */
  126         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
  127             0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL,
  128             td)) != 0)
  129                 goto out;
  130 
  131         /* Sanity check. */
  132         if (!IS_ELF(*hdr)) {
  133                 error = ENOEXEC;
  134                 goto out;
  135         }
  136 
  137         nbytes = hdr->e_shnum * hdr->e_shentsize;
  138         if (nbytes == 0 || hdr->e_shoff == 0 ||
  139             hdr->e_shentsize != sizeof(Elf_Shdr)) {
  140                 error = ENOEXEC;
  141                 goto out;
  142         }
  143 
  144         /* Allocate memory for all the section headers */
  145         shdr = malloc(nbytes, M_LINKER, M_WAITOK);
  146 
  147         /* Read all the section headers */
  148         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
  149             hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
  150             NULL, td)) != 0)
  151                 goto out;
  152 
  153         /*
  154          * We need to search for the CTF section by name, so if the
  155          * section names aren't present, then we can't locate the
  156          * .SUNW_ctf section containing the CTF data.
  157          */
  158         if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
  159                 printf("%s(%d): module %s e_shstrndx is %d, sh_type is %d\n",
  160                     __func__, __LINE__, lf->pathname, hdr->e_shstrndx,
  161                     shdr[hdr->e_shstrndx].sh_type);
  162                 error = EFTYPE;
  163                 goto out;
  164         }
  165 
  166         /* Allocate memory to buffer the section header strings. */
  167         shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER, M_WAITOK);
  168 
  169         /* Read the section header strings. */
  170         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
  171             shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
  172             UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL, td)) != 0)
  173                 goto out;
  174 
  175         /* Search for the section containing the CTF data. */
  176         for (i = 0; i < hdr->e_shnum; i++)
  177                 if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
  178                         break;
  179 
  180         /* Check if the CTF section wasn't found. */
  181         if (i >= hdr->e_shnum) {
  182                 printf("%s(%d): module %s has no .SUNW_ctf section\n",
  183                     __func__, __LINE__, lf->pathname);
  184                 error = EFTYPE;
  185                 goto out;
  186         }
  187 
  188         /* Read the CTF header. */
  189         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
  190             shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
  191             NOCRED, NULL, td)) != 0)
  192                 goto out;
  193 
  194         /* Check the CTF magic number. (XXX check for big endian!) */
  195         if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf) {
  196                 printf("%s(%d): module %s has invalid format\n",
  197                     __func__, __LINE__, lf->pathname);
  198                 error = EFTYPE;
  199                 goto out;
  200         }
  201 
  202         /* Check if version 2. */
  203         if (ctf_hdr[2] != 2) {
  204                 printf("%s(%d): module %s CTF format version is %d "
  205                     "(2 expected)\n",
  206                     __func__, __LINE__, lf->pathname, ctf_hdr[2]);
  207                 error = EFTYPE;
  208                 goto out;
  209         }
  210 
  211         /* Check if the data is compressed. */
  212         if ((ctf_hdr[3] & 0x1) != 0) {
  213                 uint32_t *u32 = (uint32_t *) ctf_hdr;
  214 
  215                 /*
  216                  * The last two fields in the CTF header are the offset
  217                  * from the end of the header to the start of the string
  218                  * data and the length of that string data. se this
  219                  * information to determine the decompressed CTF data
  220                  * buffer required.
  221                  */
  222                 sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
  223                     sizeof(ctf_hdr);
  224 
  225                 /*
  226                  * Allocate memory for the compressed CTF data, including
  227                  * the header (which isn't compressed).
  228                  */
  229                 raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
  230         } else {
  231                 /*
  232                  * The CTF data is not compressed, so the ELF section
  233                  * size is the same as the buffer size required.
  234                  */
  235                 sz = shdr[i].sh_size;
  236         }
  237 
  238         /*
  239          * Allocate memory to buffer the CTF data in it's decompressed
  240          * form.
  241          */
  242         ctftab = malloc(sz, M_LINKER, M_WAITOK);
  243 
  244         /*
  245          * Read the CTF data into the raw buffer if compressed, or
  246          * directly into the CTF buffer otherwise.
  247          */
  248         if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
  249             shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
  250             td->td_ucred, NOCRED, NULL, td)) != 0)
  251                 goto out;
  252 
  253         /* Check if decompression is required. */
  254         if (raw != NULL) {
  255                 z_stream zs;
  256                 int ret;
  257 
  258                 /*
  259                  * The header isn't compressed, so copy that into the
  260                  * CTF buffer first.
  261                  */
  262                 bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));
  263 
  264                 /* Initialise the zlib structure. */
  265                 bzero(&zs, sizeof(zs));
  266                 zs.zalloc = z_alloc;
  267                 zs.zfree = z_free;
  268 
  269                 if (inflateInit(&zs) != Z_OK) {
  270                         error = EIO;
  271                         goto out;
  272                 }
  273 
  274                 zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
  275                 zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
  276                 zs.avail_out = sz - sizeof(ctf_hdr);
  277                 zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
  278                 ret = inflate(&zs, Z_FINISH);
  279                 inflateEnd(&zs);
  280                 if (ret != Z_STREAM_END) {
  281                         printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
  282                         error = EIO;
  283                         goto out;
  284                 }
  285         }
  286 
  287         /* Got the CTF data! */
  288         ef->ctftab = ctftab;
  289         ef->ctfcnt = shdr[i].sh_size;
  290 
  291         /* We'll retain the memory allocated for the CTF data. */
  292         ctftab = NULL;
  293 
  294         /* Let the caller use the CTF data read. */
  295         lc->ctftab = ef->ctftab;
  296         lc->ctfcnt = ef->ctfcnt;
  297         lc->symtab = ef->ddbsymtab;
  298         lc->strtab = ef->ddbstrtab;
  299         lc->strcnt = ef->ddbstrcnt;
  300         lc->nsym   = ef->ddbsymcnt;
  301         lc->ctfoffp = (uint32_t **) &ef->ctfoff;
  302         lc->typoffp = (uint32_t **) &ef->typoff;
  303         lc->typlenp = &ef->typlen;
  304 
  305 out:
  306         VOP_UNLOCK(nd.ni_vp, 0);
  307         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
  308 
  309         if (hdr != NULL)
  310                 free(hdr, M_LINKER);
  311         if (shdr != NULL)
  312                 free(shdr, M_LINKER);
  313         if (shstrtab != NULL)
  314                 free(shstrtab, M_LINKER);
  315         if (ctftab != NULL)
  316                 free(ctftab, M_LINKER);
  317         if (raw != NULL)
  318                 free(raw, M_LINKER);
  319 #else
  320         error = EOPNOTSUPP;
  321 #endif
  322 
  323         return (error);
  324 }

Cache object: ed64ee3116d90175f4af112c150b8e0a


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