freebsd-dev/sys/kern/kern_ctf.c
Ryan Stone 6f6924e5a6 The in-kernel CTF parser caches the result of its first attempt to parse
CTF data from a module.  On subsequent attempts to retrieve CTF data for
a module, return an error if there no CTF data.

This fixes a panic if you try to enable fbt probes on a module with CTF
data twice.

Submitted by:	Paul Ambrose (ambrosehua AT gmail DOT com)
MFC after:	3 days
2011-11-08 15:17:54 +00:00

344 lines
9.2 KiB
C

/*-
* 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.
*
* $FreeBSD$
*/
/*
* 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;
int 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);
}