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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <unistd.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <link.h>
#include <sys/dtrace.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <libelf.h>
#include <gelf.h>
/*
* In Solaris 10 GA, the only mechanism for communicating helper information
* is through the DTrace helper pseudo-device node in /devices; there is
* no /dev link. Because of this, USDT providers and helper actions don't
* work inside of non-global zones. This issue was addressed by adding
* the /dev and having this initialization code use that /dev link. If the
* /dev link doesn't exist it falls back to looking for the /devices node
* as this code may be embedded in a binary which runs on Solaris 10 GA.
*
* Users may set the following environment variable to affect the way
* helper initialization takes place:
*
* DTRACE_DOF_INIT_DEBUG enable debugging output
* DTRACE_DOF_INIT_DISABLE disable helper loading
* DTRACE_DOF_INIT_DEVNAME set the path to the helper node
*/
static const char *devnamep = "/dev/dtrace/helper";
#if defined(sun)
static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
#endif
static const char *modname; /* Name of this load object */
static int gen; /* DOF helper generation */
#if defined(sun)
extern dof_hdr_t __SUNW_dof; /* DOF defined in the .SUNW_dof section */
#endif
static boolean_t dof_init_debug = B_FALSE; /* From DTRACE_DOF_INIT_DEBUG */
static void
dprintf(int debug, const char *fmt, ...)
{
va_list ap;
if (debug && !dof_init_debug)
return;
va_start(ap, fmt);
if (modname == NULL)
(void) fprintf(stderr, "dtrace DOF: ");
else
(void) fprintf(stderr, "dtrace DOF %s: ", modname);
(void) vfprintf(stderr, fmt, ap);
if (fmt[strlen(fmt) - 1] != '\n')
(void) fprintf(stderr, ": %s\n", strerror(errno));
va_end(ap);
}
#if !defined(sun)
static void
fixsymbol(Elf *e, Elf_Data *data, size_t idx, int nprobes, char *buf,
dof_sec_t *sec, int *fixedprobes, char *dofstrtab)
{
GElf_Sym sym;
char *s;
unsigned char *funcname;
dof_probe_t *prb;
int j = 0;
int ndx;
while (gelf_getsym(data, j++, &sym) != NULL) {
prb = (dof_probe_t *)(buf + sec->dofs_offset);
for (ndx = nprobes; ndx; ndx--, prb += 1) {
funcname = dofstrtab + prb->dofpr_func;
s = elf_strptr(e, idx, sym.st_name);
if (strcmp(s, funcname) == 0) {
dprintf(1, "fixing %s() symbol\n", s);
prb->dofpr_addr = sym.st_value;
(*fixedprobes)++;
}
}
if (*fixedprobes == nprobes)
break;
}
}
#endif
#if defined(sun)
#pragma init(dtrace_dof_init)
#else
static void dtrace_dof_init(void) __attribute__ ((constructor));
#endif
static void
dtrace_dof_init(void)
{
#if defined(sun)
dof_hdr_t *dof = &__SUNW_dof;
#else
dof_hdr_t *dof = NULL;
#endif
#ifdef _LP64
Elf64_Ehdr *elf;
#else
Elf32_Ehdr *elf;
#endif
dof_helper_t dh;
Link_map *lmp;
#if defined(sun)
Lmid_t lmid;
#else
u_long lmid = 0;
dof_sec_t *sec;
size_t i;
#endif
int fd;
const char *p;
#if !defined(sun)
Elf *e;
Elf_Scn *scn = NULL;
Elf_Data *symtabdata = NULL, *dynsymdata = NULL;
GElf_Shdr shdr;
int efd, nprobes;
char *s;
size_t shstridx, symtabidx = 0, dynsymidx = 0;
unsigned char *dofstrtab = NULL;
unsigned char *buf;
int fixedprobes = 0;
#endif
if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
return;
if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
dof_init_debug = B_TRUE;
if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
dprintf(1, "couldn't discover module name or address\n");
return;
}
#if defined(sun)
if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
dprintf(1, "couldn't discover link map ID\n");
return;
}
#endif
if ((modname = strrchr(lmp->l_name, '/')) == NULL)
modname = lmp->l_name;
else
modname++;
#if !defined(sun)
elf_version(EV_CURRENT);
if ((efd = open(lmp->l_name, O_RDONLY, 0)) < 0) {
dprintf(1, "couldn't open file for reading\n");
return;
}
if ((e = elf_begin(efd, ELF_C_READ, NULL)) == NULL) {
dprintf(1, "elf_begin failed\n");
close(efd);
return;
}
elf_getshdrstrndx(e, &shstridx);
dof = NULL;
while ((scn = elf_nextscn(e, scn)) != NULL) {
gelf_getshdr(scn, &shdr);
if (shdr.sh_type == SHT_SYMTAB) {
symtabidx = shdr.sh_link;
symtabdata = elf_getdata(scn, NULL);
} else if (shdr.sh_type == SHT_DYNSYM) {
dynsymidx = shdr.sh_link;
dynsymdata = elf_getdata(scn, NULL);
} else if (shdr.sh_type == SHT_PROGBITS) {
s = elf_strptr(e, shstridx, shdr.sh_name);
if (s && strcmp(s, ".SUNW_dof") == 0) {
dof = elf_getdata(scn, NULL)->d_buf;
}
}
}
if (dof == NULL) {
dprintf(1, "SUNW_dof section not found\n");
elf_end(e);
close(efd);
return;
}
#endif
if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
dprintf(0, ".SUNW_dof section corrupt\n");
return;
}
elf = (void *)lmp->l_addr;
dh.dofhp_dof = (uintptr_t)dof;
dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
if (lmid == 0) {
(void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
"%s", modname);
} else {
(void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
"LM%lu`%s", lmid, modname);
}
if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
devnamep = p;
if ((fd = open64(devnamep, O_RDWR)) < 0) {
dprintf(1, "failed to open helper device %s", devnamep);
#if defined(sun)
/*
* If the device path wasn't explicitly set, try again with
* the old device path.
*/
if (p != NULL)
return;
devnamep = olddevname;
if ((fd = open64(devnamep, O_RDWR)) < 0) {
dprintf(1, "failed to open helper device %s", devnamep);
return;
}
#else
return;
#endif
}
#if !defined(sun)
/*
* We need to fix the base address of each probe since this wasn't
* done by ld(1). (ld(1) needs to grow support for parsing the
* SUNW_dof section).
*
* The complexity of this is not that great. The first for loop
* iterates over the sections inside the DOF file. There are usually
* 10 sections here. We asume the STRTAB section comes first and the
* PROBES section comes after. Since we are only interested in fixing
* data inside the PROBES section we quit the for loop after processing
* the PROBES section. It's usually the case that the first section
* is the STRTAB section and the second section is the PROBES section,
* so this for loop is not meaningful when doing complexity analysis.
*
* After finding the probes section, we iterate over the symbols
* in the symtab section. When we find a symbol name that matches
* the probe function name, we fix it. If we have fixed all the
* probes, we exit all the loops and we are done.
* The number of probes is given by the variable 'nprobes' and this
* depends entirely on the user, but some optimizations were done.
*
* We are assuming the number of probes is less than the number of
* symbols (libc can have 4k symbols, for example).
*/
sec = (dof_sec_t *)(dof + 1);
buf = (char *)dof;
for (i = 0; i < dof->dofh_secnum; i++, sec++) {
if (sec->dofs_type == DOF_SECT_STRTAB)
dofstrtab = (unsigned char *)(buf + sec->dofs_offset);
else if (sec->dofs_type == DOF_SECT_PROBES && dofstrtab)
break;
}
nprobes = sec->dofs_size / sec->dofs_entsize;
fixsymbol(e, symtabdata, symtabidx, nprobes, buf, sec, &fixedprobes,
dofstrtab);
if (fixedprobes != nprobes) {
/*
* If we haven't fixed all the probes using the
* symtab section, look inside the dynsym
* section.
*/
fixsymbol(e, dynsymdata, dynsymidx, nprobes, buf, sec,
&fixedprobes, dofstrtab);
}
if (fixedprobes != nprobes) {
fprintf(stderr, "WARNING: number of probes "
"fixed does not match the number of "
"defined probes (%d != %d, "
"respectively)\n", fixedprobes, nprobes);
fprintf(stderr, "WARNING: some probes might "
"not fire or your program might crash\n");
}
#endif
if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
dprintf(1, "DTrace ioctl failed for DOF at %p", dof);
else {
dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
#if !defined(sun)
gen = dh.gen;
#endif
}
(void) close(fd);
#if !defined(sun)
elf_end(e);
(void) close(efd);
#endif
}
#if defined(sun)
#pragma fini(dtrace_dof_fini)
#else
static void dtrace_dof_fini(void) __attribute__ ((destructor));
#endif
static void
dtrace_dof_fini(void)
{
int fd;
if ((fd = open64(devnamep, O_RDWR)) < 0) {
dprintf(1, "failed to open helper device %s", devnamep);
return;
}
if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, &gen)) == -1)
dprintf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
else
dprintf(1, "DTrace ioctl removed DOF (%d)\n", gen);
(void) close(fd);
}
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