freebsd-nq/lib/libkvm/kvm.c
Robert Watson ccd8bad0bb A first cut at teaching libkvm how to deal with dynamic per-CPU storage
(DPCPU):

A new API, kvm_dpcpu_setcpu(3), selects the active CPU for the purposes
of DPCPU.  Calls to kvm_nlist(3) will automatically translate DPCPU
symbols and return a pointer to the current CPU's version of the data.
Consumers needing to read the same symbol on several CPUs will invoke a
series of setcpu/nlist calls, one per CPU of interest.

This addition makes it possible for tools like netstat(1) to query the
values of DPCPU variables during crashdump analysis, and is based on
similar code handling virtualized global variables.

MFC after:	1 week
Sponsored by:	Juniper Networks, Inc.
2010-03-01 00:27:55 +00:00

621 lines
15 KiB
C

/*-
* Copyright (c) 1989, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software developed by the Computer Systems
* Engineering group at Lawrence Berkeley Laboratory under DARPA contract
* BG 91-66 and contributed to Berkeley.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)kvm.c 8.2 (Berkeley) 2/13/94";
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#define _WANT_VNET
#include <sys/user.h>
#include <sys/proc.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/linker.h>
#include <net/vnet.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <machine/vmparam.h>
#include <ctype.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <nlist.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include "kvm_private.h"
/* from src/lib/libc/gen/nlist.c */
int __fdnlist(int, struct nlist *);
char *
kvm_geterr(kd)
kvm_t *kd;
{
return (kd->errbuf);
}
#include <stdarg.h>
/*
* Report an error using printf style arguments. "program" is kd->program
* on hard errors, and 0 on soft errors, so that under sun error emulation,
* only hard errors are printed out (otherwise, programs like gdb will
* generate tons of error messages when trying to access bogus pointers).
*/
void
_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (program != NULL) {
(void)fprintf(stderr, "%s: ", program);
(void)vfprintf(stderr, fmt, ap);
(void)fputc('\n', stderr);
} else
(void)vsnprintf(kd->errbuf,
sizeof(kd->errbuf), (char *)fmt, ap);
va_end(ap);
}
void
_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
{
va_list ap;
int n;
va_start(ap, fmt);
if (program != NULL) {
(void)fprintf(stderr, "%s: ", program);
(void)vfprintf(stderr, fmt, ap);
(void)fprintf(stderr, ": %s\n", strerror(errno));
} else {
char *cp = kd->errbuf;
(void)vsnprintf(cp, sizeof(kd->errbuf), (char *)fmt, ap);
n = strlen(cp);
(void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
strerror(errno));
}
va_end(ap);
}
void *
_kvm_malloc(kd, n)
kvm_t *kd;
size_t n;
{
void *p;
if ((p = calloc(n, sizeof(char))) == NULL)
_kvm_err(kd, kd->program, "can't allocate %u bytes: %s",
n, strerror(errno));
return (p);
}
static kvm_t *
_kvm_open(kd, uf, mf, flag, errout)
kvm_t *kd;
const char *uf;
const char *mf;
int flag;
char *errout;
{
struct stat st;
kd->vmfd = -1;
kd->pmfd = -1;
kd->nlfd = -1;
kd->vmst = 0;
kd->procbase = 0;
kd->argspc = 0;
kd->argv = 0;
if (uf == 0)
uf = getbootfile();
else if (strlen(uf) >= MAXPATHLEN) {
_kvm_err(kd, kd->program, "exec file name too long");
goto failed;
}
if (flag & ~O_RDWR) {
_kvm_err(kd, kd->program, "bad flags arg");
goto failed;
}
if (mf == 0)
mf = _PATH_MEM;
if ((kd->pmfd = open(mf, flag, 0)) < 0) {
_kvm_syserr(kd, kd->program, "%s", mf);
goto failed;
}
if (fstat(kd->pmfd, &st) < 0) {
_kvm_syserr(kd, kd->program, "%s", mf);
goto failed;
}
if (S_ISREG(st.st_mode) && st.st_size <= 0) {
errno = EINVAL;
_kvm_syserr(kd, kd->program, "empty file");
goto failed;
}
if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
_kvm_syserr(kd, kd->program, "%s", mf);
goto failed;
}
if (S_ISCHR(st.st_mode)) {
/*
* If this is a character special device, then check that
* it's /dev/mem. If so, open kmem too. (Maybe we should
* make it work for either /dev/mem or /dev/kmem -- in either
* case you're working with a live kernel.)
*/
if (strcmp(mf, _PATH_DEVNULL) == 0) {
kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
return (kd);
} else if (strcmp(mf, _PATH_MEM) == 0) {
if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
goto failed;
}
if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
goto failed;
}
return (kd);
}
}
/*
* This is a crash dump.
* Initialize the virtual address translation machinery,
* but first setup the namelist fd.
*/
if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
_kvm_syserr(kd, kd->program, "%s", uf);
goto failed;
}
if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
_kvm_syserr(kd, kd->program, "%s", uf);
goto failed;
}
if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0)
kd->rawdump = 1;
if (_kvm_initvtop(kd) < 0)
goto failed;
return (kd);
failed:
/*
* Copy out the error if doing sane error semantics.
*/
if (errout != 0)
strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
(void)kvm_close(kd);
return (0);
}
kvm_t *
kvm_openfiles(uf, mf, sf, flag, errout)
const char *uf;
const char *mf;
const char *sf __unused;
int flag;
char *errout;
{
kvm_t *kd;
if ((kd = calloc(1, sizeof(*kd))) == NULL) {
(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
return (0);
}
kd->program = 0;
return (_kvm_open(kd, uf, mf, flag, errout));
}
kvm_t *
kvm_open(uf, mf, sf, flag, errstr)
const char *uf;
const char *mf;
const char *sf __unused;
int flag;
const char *errstr;
{
kvm_t *kd;
if ((kd = calloc(1, sizeof(*kd))) == NULL) {
if (errstr != NULL)
(void)fprintf(stderr, "%s: %s\n",
errstr, strerror(errno));
return (0);
}
kd->program = errstr;
return (_kvm_open(kd, uf, mf, flag, NULL));
}
int
kvm_close(kd)
kvm_t *kd;
{
int error = 0;
if (kd->pmfd >= 0)
error |= close(kd->pmfd);
if (kd->vmfd >= 0)
error |= close(kd->vmfd);
if (kd->nlfd >= 0)
error |= close(kd->nlfd);
if (kd->vmst)
_kvm_freevtop(kd);
if (kd->procbase != 0)
free((void *)kd->procbase);
if (kd->argbuf != 0)
free((void *) kd->argbuf);
if (kd->argspc != 0)
free((void *) kd->argspc);
if (kd->argv != 0)
free((void *)kd->argv);
free((void *)kd);
return (0);
}
/*
* Walk the list of unresolved symbols, generate a new list and prefix the
* symbol names, try again, and merge back what we could resolve.
*/
static int
kvm_fdnlist_prefix(kvm_t *kd, struct nlist *nl, int missing, const char *prefix,
uintptr_t (*validate_fn)(kvm_t *, uintptr_t))
{
struct nlist *n, *np, *p;
char *cp, *ce;
size_t len;
int unresolved;
/*
* Calculate the space we need to malloc for nlist and names.
* We are going to store the name twice for later lookups: once
* with the prefix and once the unmodified name delmited by \0.
*/
len = 0;
unresolved = 0;
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
len += sizeof(struct nlist) + strlen(prefix) +
2 * (strlen(p->n_name) + 1);
unresolved++;
}
if (unresolved == 0)
return (unresolved);
/* Add space for the terminating nlist entry. */
len += sizeof(struct nlist);
unresolved++;
/* Alloc one chunk for (nlist, [names]) and setup pointers. */
n = np = malloc(len);
bzero(n, len);
if (n == NULL)
return (missing);
cp = ce = (char *)np;
cp += unresolved * sizeof(struct nlist);
ce += len;
/* Generate shortened nlist with special prefix. */
unresolved = 0;
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
bcopy(p, np, sizeof(struct nlist));
/* Save the new\0orig. name so we can later match it again. */
len = snprintf(cp, ce - cp, "%s%s%c%s", prefix,
(prefix[0] != '\0' && p->n_name[0] == '_') ?
(p->n_name + 1) : p->n_name, '\0', p->n_name);
if (len >= ce - cp)
continue;
np->n_name = cp;
cp += len + 1;
np++;
unresolved++;
}
/* Do lookup on the reduced list. */
np = n;
unresolved = __fdnlist(kd->nlfd, np);
/* Check if we could resolve further symbols and update the list. */
if (unresolved >= 0 && unresolved < missing) {
/* Find the first freshly resolved entry. */
for (; np->n_name && np->n_name[0]; np++)
if (np->n_type != N_UNDF)
break;
/*
* The lists are both in the same order,
* so we can walk them in parallel.
*/
for (p = nl; np->n_name && np->n_name[0] &&
p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
/* Skip expanded name and compare to orig. one. */
cp = np->n_name + strlen(np->n_name) + 1;
if (strcmp(cp, p->n_name))
continue;
/* Update nlist with new, translated results. */
p->n_type = np->n_type;
p->n_other = np->n_other;
p->n_desc = np->n_desc;
if (validate_fn)
p->n_value = (*validate_fn)(kd, np->n_value);
else
p->n_value = np->n_value;
missing--;
/* Find next freshly resolved entry. */
for (np++; np->n_name && np->n_name[0]; np++)
if (np->n_type != N_UNDF)
break;
}
}
/* We could assert missing = unresolved here. */
free(n);
return (unresolved);
}
int
_kvm_nlist(kvm_t *kd, struct nlist *nl, int initialize)
{
struct nlist *p;
int nvalid;
struct kld_sym_lookup lookup;
int error;
char *prefix = "", symname[1024]; /* XXX-BZ symbol name length limit? */
int tried_vnet, tried_dpcpu;
/*
* If we can't use the kld symbol lookup, revert to the
* slow library call.
*/
if (!ISALIVE(kd)) {
error = __fdnlist(kd->nlfd, nl);
if (error <= 0) /* Hard error or success. */
return (error);
if (_kvm_vnet_initialized(kd, initialize))
error = kvm_fdnlist_prefix(kd, nl, error,
VNET_SYMPREFIX, _kvm_vnet_validaddr);
if (error > 0 && _kvm_dpcpu_initialized(kd, initialize))
error = kvm_fdnlist_prefix(kd, nl, error,
"pcpu_entry_", _kvm_dpcpu_validaddr);
return (error);
}
/*
* We can use the kld lookup syscall. Go through each nlist entry
* and look it up with a kldsym(2) syscall.
*/
nvalid = 0;
tried_vnet = 0;
tried_dpcpu = 0;
again:
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
lookup.version = sizeof(lookup);
lookup.symvalue = 0;
lookup.symsize = 0;
error = snprintf(symname, sizeof(symname), "%s%s", prefix,
(prefix[0] != '\0' && p->n_name[0] == '_') ?
(p->n_name + 1) : p->n_name);
if (error >= sizeof(symname))
continue;
lookup.symname = symname;
if (lookup.symname[0] == '_')
lookup.symname++;
if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
p->n_type = N_TEXT;
p->n_other = 0;
p->n_desc = 0;
if (_kvm_vnet_initialized(kd, initialize) &&
!strcmp(prefix, VNET_SYMPREFIX))
p->n_value =
_kvm_vnet_validaddr(kd, lookup.symvalue);
else if (_kvm_dpcpu_initialized(kd, initialize) &&
!strcmp(prefix, "pcpu_entry_"))
p->n_value =
_kvm_dpcpu_validaddr(kd, lookup.symvalue);
else
p->n_value = lookup.symvalue;
++nvalid;
/* lookup.symsize */
}
}
/*
* Check the number of entries that weren't found. If they exist,
* try again with a prefix for virtualized or DPCPU symbol names.
*/
error = ((p - nl) - nvalid);
if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) {
tried_vnet = 1;
prefix = VNET_SYMPREFIX;
goto again;
}
if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) {
tried_dpcpu = 1;
prefix = "pcpu_entry_";
goto again;
}
/*
* Return the number of entries that weren't found. If they exist,
* also fill internal error buffer.
*/
error = ((p - nl) - nvalid);
if (error)
_kvm_syserr(kd, kd->program, "kvm_nlist");
return (error);
}
int
kvm_nlist(kd, nl)
kvm_t *kd;
struct nlist *nl;
{
/*
* If called via the public interface, permit intialization of
* further virtualized modules on demand.
*/
return (_kvm_nlist(kd, nl, 1));
}
ssize_t
kvm_read(kd, kva, buf, len)
kvm_t *kd;
u_long kva;
void *buf;
size_t len;
{
int cc;
char *cp;
if (ISALIVE(kd)) {
/*
* We're using /dev/kmem. Just read straight from the
* device and let the active kernel do the address translation.
*/
errno = 0;
if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
_kvm_err(kd, 0, "invalid address (%x)", kva);
return (-1);
}
cc = read(kd->vmfd, buf, len);
if (cc < 0) {
_kvm_syserr(kd, 0, "kvm_read");
return (-1);
} else if (cc < len)
_kvm_err(kd, kd->program, "short read");
return (cc);
} else {
cp = buf;
while (len > 0) {
off_t pa;
cc = _kvm_kvatop(kd, kva, &pa);
if (cc == 0)
return (-1);
if (cc > len)
cc = len;
errno = 0;
if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
_kvm_syserr(kd, 0, _PATH_MEM);
break;
}
cc = read(kd->pmfd, cp, cc);
if (cc < 0) {
_kvm_syserr(kd, kd->program, "kvm_read");
break;
}
/*
* If kvm_kvatop returns a bogus value or our core
* file is truncated, we might wind up seeking beyond
* the end of the core file in which case the read will
* return 0 (EOF).
*/
if (cc == 0)
break;
cp += cc;
kva += cc;
len -= cc;
}
return (cp - (char *)buf);
}
/* NOTREACHED */
}
ssize_t
kvm_write(kd, kva, buf, len)
kvm_t *kd;
u_long kva;
const void *buf;
size_t len;
{
int cc;
if (ISALIVE(kd)) {
/*
* Just like kvm_read, only we write.
*/
errno = 0;
if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
_kvm_err(kd, 0, "invalid address (%x)", kva);
return (-1);
}
cc = write(kd->vmfd, buf, len);
if (cc < 0) {
_kvm_syserr(kd, 0, "kvm_write");
return (-1);
} else if (cc < len)
_kvm_err(kd, kd->program, "short write");
return (cc);
} else {
_kvm_err(kd, kd->program,
"kvm_write not implemented for dead kernels");
return (-1);
}
/* NOTREACHED */
}