kern_ctf.c

Go to the documentation of this file.

/*-
 * Copyright (c) 2008 John Birrell <jb@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $BSDSUniX$
 */

/*
 * Note this file is included by both link_elf.c and link_elf_obj.c.
 *
 * The CTF header structure definition can't be used here because it's
 * (annoyingly) covered by the CDDL. We will just use a few bytes from
 * it as an integer array where we 'know' what they mean.
 */
#define CTF_HDR_SIZE            36
#define CTF_HDR_STRTAB_U32      7
#define CTF_HDR_STRLEN_U32      8

#ifdef DDB_CTF
static void *
z_alloc(void *nil, u_int items, u_int size)
{
        void *ptr;

        ptr = malloc(items * size, M_TEMP, M_NOWAIT);
        return ptr;
}

static void
z_free(void *nil, void *ptr)
{
        free(ptr, M_TEMP);
}

#endif

static int
link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
{
#ifdef DDB_CTF
        Elf_Ehdr *hdr = NULL;
        Elf_Shdr *shdr = NULL;
        caddr_t ctftab = NULL;
        caddr_t raw = NULL;
        caddr_t shstrtab = NULL;
        elf_file_t ef = (elf_file_t) lf;
        int flags;
        int i;
        int nbytes;
        ssize_t resid;
        int vfslocked;
        size_t sz;
        struct nameidata nd;
        struct thread *td = curthread;
        uint8_t ctf_hdr[CTF_HDR_SIZE];
#endif
        int error = 0;

        if (lf == NULL || lc == NULL)
                return (EINVAL);

        /* Set the defaults for no CTF present. That's not a crime! */
        bzero(lc, sizeof(*lc));

#ifdef DDB_CTF
        /*
         * First check if we've tried to load CTF data previously and the
         * CTF ELF section wasn't found. We flag that condition by setting
         * ctfcnt to -1. See below.
         */
        if (ef->ctfcnt < 0)
                return (EFTYPE);

        /* Now check if we've already loaded the CTF data.. */
        if (ef->ctfcnt > 0) {
                /* We only need to load once. */
                lc->ctftab = ef->ctftab;
                lc->ctfcnt = ef->ctfcnt;
                lc->symtab = ef->ddbsymtab;
                lc->strtab = ef->ddbstrtab;
                lc->strcnt = ef->ddbstrcnt;
                lc->nsym   = ef->ddbsymcnt;
                lc->ctfoffp = (uint32_t **) &ef->ctfoff;
                lc->typoffp = (uint32_t **) &ef->typoff;
                lc->typlenp = &ef->typlen;
                return (0);
        }

        /*
         * We need to try reading the CTF data. Flag no CTF data present
         * by default and if we actually succeed in reading it, we'll
         * update ctfcnt to the number of bytes read.
         */
        ef->ctfcnt = -1;

        NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, lf->pathname, td);
        flags = FREAD;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error)
                return (error);
        vfslocked = NDHASGIANT(&nd);
        NDFREE(&nd, NDF_ONLY_PNBUF);

        /* Allocate memory for the FLF header. */
        if ((hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK)) == NULL) {
                error = ENOMEM;
                goto out;
        }

        /* Read the ELF header. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
            0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
            td)) != 0)
                goto out;

        /* Sanity check. */
        if (!IS_ELF(*hdr)) {
                error = ENOEXEC;
                goto out;
        }

        nbytes = hdr->e_shnum * hdr->e_shentsize;
        if (nbytes == 0 || hdr->e_shoff == 0 ||
            hdr->e_shentsize != sizeof(Elf_Shdr)) {
                error = ENOEXEC;
                goto out;
        }

        /* Allocate memory for all the section headers */
        if ((shdr = malloc(nbytes, M_LINKER, M_WAITOK)) == NULL) {
                error = ENOMEM;
                goto out;
        }

        /* Read all the section headers */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
            hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
            &resid, td)) != 0)
                goto out;

        /*
         * We need to search for the CTF section by name, so if the
         * section names aren't present, then we can't locate the
         * .SUNW_ctf section containing the CTF data.
         */
        if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
                printf("%s(%d): module %s e_shstrndx is %d, sh_type is %d\n",
                    __func__, __LINE__, lf->pathname, hdr->e_shstrndx,
                    shdr[hdr->e_shstrndx].sh_type);
                error = EFTYPE;
                goto out;
        }

        /* Allocate memory to buffer the section header strings. */
        if ((shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER,
            M_WAITOK)) == NULL) {
                error = ENOMEM;
                goto out;
        }

        /* Read the section header strings. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
            shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
            UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
            td)) != 0)
                goto out;

        /* Search for the section containing the CTF data. */
        for (i = 0; i < hdr->e_shnum; i++)
                if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
                        break;

        /* Check if the CTF section wasn't found. */
        if (i >= hdr->e_shnum) {
                printf("%s(%d): module %s has no .SUNW_ctf section\n",
                    __func__, __LINE__, lf->pathname);
                error = EFTYPE;
                goto out;
        }

        /* Read the CTF header. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
            shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
            NOCRED, &resid, td)) != 0)
                goto out;

        /* Check the CTF magic number. (XXX check for big endian!) */
        if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf) {
                printf("%s(%d): module %s has invalid format\n",
                    __func__, __LINE__, lf->pathname);
                error = EFTYPE;
                goto out;
        }

        /* Check if version 2. */
        if (ctf_hdr[2] != 2) {
                printf("%s(%d): module %s CTF format version is %d "
                    "(2 expected)\n",
                    __func__, __LINE__, lf->pathname, ctf_hdr[2]);
                error = EFTYPE;
                goto out;
        }

        /* Check if the data is compressed. */
        if ((ctf_hdr[3] & 0x1) != 0) {
                uint32_t *u32 = (uint32_t *) ctf_hdr;

                /*
                 * The last two fields in the CTF header are the offset
                 * from the end of the header to the start of the string
                 * data and the length of that string data. se this
                 * information to determine the decompressed CTF data
                 * buffer required.
                 */
                sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
                    sizeof(ctf_hdr);

                /*
                 * Allocate memory for the compressed CTF data, including
                 * the header (which isn't compressed).
                 */
                if ((raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK)) == NULL) {
                        error = ENOMEM;
                        goto out;
                }
        } else {
                /*
                 * The CTF data is not compressed, so the ELF section
                 * size is the same as the buffer size required.
                 */
                sz = shdr[i].sh_size;
        }

        /*
         * Allocate memory to buffer the CTF data in it's decompressed
         * form.
         */
        if ((ctftab = malloc(sz, M_LINKER, M_WAITOK)) == NULL) {
                error = ENOMEM;
                goto out;
        }

        /*
         * Read the CTF data into the raw buffer if compressed, or
         * directly into the CTF buffer otherwise.
         */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
            shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
            td->td_ucred, NOCRED, &resid, td)) != 0)
                goto out;

        /* Check if decompression is required. */
        if (raw != NULL) {
                z_stream zs;
                int ret;

                /*
                 * The header isn't compressed, so copy that into the
                 * CTF buffer first.
                 */
                bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));

                /* Initialise the zlib structure. */
                bzero(&zs, sizeof(zs));
                zs.zalloc = z_alloc;
                zs.zfree = z_free;

                if (inflateInit(&zs) != Z_OK) {
                        error = EIO;
                        goto out;
                }

                zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
                zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
                zs.avail_out = sz - sizeof(ctf_hdr);
                zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
                if ((ret = inflate(&zs, Z_FINISH)) != Z_STREAM_END) {
                        printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
                        error = EIO;
                        goto out;
                }
        }

        /* Got the CTF data! */
        ef->ctftab = ctftab;
        ef->ctfcnt = shdr[i].sh_size;

        /* We'll retain the memory allocated for the CTF data. */
        ctftab = NULL;

        /* Let the caller use the CTF data read. */
        lc->ctftab = ef->ctftab;
        lc->ctfcnt = ef->ctfcnt;
        lc->symtab = ef->ddbsymtab;
        lc->strtab = ef->ddbstrtab;
        lc->strcnt = ef->ddbstrcnt;
        lc->nsym   = ef->ddbsymcnt;
        lc->ctfoffp = (uint32_t **) &ef->ctfoff;
        lc->typoffp = (uint32_t **) &ef->typoff;
        lc->typlenp = &ef->typlen;

out:
        VOP_UNLOCK(nd.ni_vp, 0);
        vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
        VFS_UNLOCK_GIANT(vfslocked);

        if (hdr != NULL)
                free(hdr, M_LINKER);
        if (shdr != NULL)
                free(shdr, M_LINKER);
        if (shstrtab != NULL)
                free(shstrtab, M_LINKER);
        if (ctftab != NULL)
                free(ctftab, M_LINKER);
        if (raw != NULL)
                free(raw, M_LINKER);
#else
        error = EOPNOTSUPP;
#endif

        return (error);
}