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Overhaul the ktrace subsystem a bit. For the most part, the actual vnode

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operations to dump a ktrace event out to an output file are now handled
asychronously by a ktrace worker thread.  This enables most ktrace events
to not need Giant once p_tracep and p_traceflag are suitably protected by
the new ktrace_lock.

There is a single todo list of pending ktrace requests.  The various
ktrace tracepoints allocate a ktrace request object and tack it onto the
end of the queue.  The ktrace kernel thread grabs requests off the head of
the queue and processes them using the trace vnode and credentials of the
thread triggering the event.

Since we cannot assume that the user memory referenced when doing a
ktrgenio() will be valid and since we can't access it from the ktrace
worker thread without a bit of hassle anyways, ktrgenio() requests are
still handled synchronously.  However, in order to ensure that the requests
from a given thread still maintain relative order to one another, when a
synchronous ktrace event (such as a genio event) is triggered, we still put
the request object on the todo list to synchronize with the worker thread.
The original thread blocks atomically with putting the item on the queue.
When the worker thread comes across an asynchronous request, it wakes up
the original thread and then blocks to ensure it doesn't manage to write a
later event before the original thread has a chance to write out the
synchronous event.  When the original thread wakes up, it writes out the
synchronous using its own context and then finally wakes the worker thread
back up.  Yuck.  The sychronous events aren't pretty but they do work.

Since ktrace events can be triggered in fairly low-level areas (msleep()
and cv_wait() for example) the ktrace code is designed to use very few
locks when posting an event (currently just the ktrace_mtx lock and the
vnode interlock to bump the refcoun on the trace vnode).  This also means
that we can't allocate a ktrace request object when an event is triggered.
Instead, ktrace request objects are allocated from a pre-allocated pool
and returned to the pool after a request is serviced.

The size of this pool defaults to 100 objects, which is about 13k on an
i386 kernel.  The size of the pool can be adjusted at compile time via the
KTRACE_REQUEST_POOL kernel option, at boot time via the
kern.ktrace_request_pool loader tunable, or at runtime via the
kern.ktrace_request_pool sysctl.

If the pool of request objects is exhausted, then a warning message is
printed to the console.  The message is rate-limited in that it is only
printed once until the size of the pool is adjusted via the sysctl.

I have tested all kernel traces but have not tested user traces submitted
by utrace(2), though they should work fine in theory.

Since a ktrace request has several properties (content of event, trace
vnode, details of originating process, credentials for I/O, etc.), I chose
to drop the first argument to the various ktrfoo() functions.  Currently
the functions just assume the event is posted from curthread.  If there is
a great desire to do so, I suppose I could instead put back the first
argument but this time make it a thread pointer instead of a vnode pointer.

Also, KTRPOINT() now takes a thread as its first argument instead of a
process.  This is because the check for a recursive ktrace event is now
per-thread instead of process-wide.

Tested on:	i386
Compiles on:	sparc64, alpha
This commit is contained in:
jhb 2002-06-07 05:32:59 +00:00
parent 92c9b7b198
commit ab80d12ef1
4 changed files with 471 additions and 238 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
sys/conf/NOTES
View File

@ -216,9 +216,16 @@ options DDB_UNATTENDED
options GDB_REMOTE_CHAT
#
# KTRACE enables the system-call tracing facility ktrace(2).
# KTRACE enables the system-call tracing facility ktrace(2). To be more
# SMP-friendly, KTRACE uses a worker thread to process most trace events
# asynchronously to the thread generating the event. This requires a
# pre-allocated store of objects representing trace events. The
# KTRACE_REQUEST_POOL option specifies the initial size of this store.
# The size of the pool can be adjusted both at boottime and runtime via
# the kern.ktrace_request_pool tunable and sysctl.
#
options KTRACE #kernel tracing
options KTRACE_REQUEST_POOL=101
#
# KTR is a kernel tracing mechanism imported from BSD/OS. Currently it

1
sys/conf/options
View File

@ -77,6 +77,7 @@ GDB_REMOTE_CHAT opt_ddb.h
NODEVFS opt_devfs.h
HW_WDOG
KTRACE
KTRACE_REQUEST_POOL opt_ktrace.h # Size of ktrace request pool
LIBICONV
MD_ROOT opt_md.h
MD_ROOT_SIZE opt_md.h

671
sys/kern/kern_ktrace.c
View File

@ -38,232 +38,420 @@
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/malloc.h>
#include <sys/sema.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/jail.h>
#include <sys/sysproto.h>
static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
#ifdef KTRACE
static struct ktr_header *ktrgetheader(int type);
static void ktrwrite(struct vnode *, struct ktr_header *, struct uio *);
static int ktrcanset(struct thread *, struct proc *);
static int ktrsetchildren(struct thread *, struct proc *, int, int, struct vnode *);
static int ktrops(struct thread *, struct proc *, int, int, struct vnode *);
#ifndef KTRACE_REQUEST_POOL
#define KTRACE_REQUEST_POOL 100
#endif
static struct ktr_header *
ktrgetheader(type)
int type;
struct ktr_request {
struct ktr_header ktr_header;
struct ucred *ktr_cred;
struct vnode *ktr_vp;
union {
struct ktr_syscall ktr_syscall;
struct ktr_sysret ktr_sysret;
struct ktr_genio ktr_genio;
struct ktr_psig ktr_psig;
struct ktr_csw ktr_csw;
} ktr_data;
int ktr_synchronous;
STAILQ_ENTRY(ktr_request) ktr_list;
};
static int data_lengths[] = {
0, /* none */
offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
sizeof(struct ktr_sysret), /* KTR_SYSRET */
0, /* KTR_NAMEI */
sizeof(struct ktr_genio), /* KTR_GENIO */
sizeof(struct ktr_psig), /* KTR_PSIG */
sizeof(struct ktr_csw), /* KTR_CSW */
0 /* KTR_USER */
};
static STAILQ_HEAD(, ktr_request) ktr_todo;
static STAILQ_HEAD(, ktr_request) ktr_free;
static uint ktr_requestpool = KTRACE_REQUEST_POOL;
TUNABLE_INT("kern.ktrace_request_pool", &ktr_requestpool);
static int print_message = 1;
struct mtx ktrace_mtx;
static struct sema ktrace_sema;
static void ktrace_init(void *dummy);
static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
static uint ktrace_resize_pool(uint newsize);
static struct ktr_request *ktr_getrequest(int type);
static void ktr_submitrequest(struct ktr_request *req);
static void ktr_freerequest(struct ktr_request *req);
static void ktr_loop(void *dummy);
static void ktr_writerequest(struct ktr_request *req);
static int ktrcanset(struct thread *,struct proc *);
static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
static void
ktrace_init(void *dummy)
{
register struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
int i;
MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
M_KTRACE, M_WAITOK);
kth->ktr_type = type;
microtime(&kth->ktr_time);
kth->ktr_pid = p->p_pid;
bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
return (kth);
mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
sema_init(&ktrace_sema, 0, "ktrace");
STAILQ_INIT(&ktr_todo);
STAILQ_INIT(&ktr_free);
for (i = 0; i < ktr_requestpool; i++) {
req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
}
kthread_create(ktr_loop, NULL, NULL, RFHIGHPID, "ktrace");
}
SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
static int
sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
{
struct thread *td;
uint newsize, oldsize, wantsize;
int error;
/* Handle easy read-only case first to avoid warnings from GCC. */
if (!req->newptr) {
mtx_lock(&ktrace_mtx);
oldsize = ktr_requestpool;
mtx_unlock(&ktrace_mtx);
return (SYSCTL_OUT(req, &oldsize, sizeof(uint)));
}
error = SYSCTL_IN(req, &wantsize, sizeof(uint));
if (error)
return (error);
td = curthread;
td->td_inktrace = 1;
mtx_lock(&ktrace_mtx);
oldsize = ktr_requestpool;
newsize = ktrace_resize_pool(wantsize);
mtx_unlock(&ktrace_mtx);
td->td_inktrace = 0;
error = SYSCTL_OUT(req, &oldsize, sizeof(uint));
if (error)
return (error);
if (newsize != wantsize)
return (ENOSPC);
return (0);
}
SYSCTL_PROC(_kern, OID_AUTO, ktrace_request_pool, CTLTYPE_UINT|CTLFLAG_RW,
&ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
static uint
ktrace_resize_pool(uint newsize)
{
struct ktr_request *req;
mtx_assert(&ktrace_mtx, MA_OWNED);
print_message = 1;
if (newsize == ktr_requestpool)
return (newsize);
if (newsize < ktr_requestpool)
/* Shrink pool down to newsize if possible. */
while (ktr_requestpool > newsize) {
req = STAILQ_FIRST(&ktr_free);
if (req == NULL)
return (ktr_requestpool);
STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
ktr_requestpool--;
mtx_unlock(&ktrace_mtx);
free(req, M_KTRACE);
mtx_lock(&ktrace_mtx);
}
else
/* Grow pool up to newsize. */
while (ktr_requestpool < newsize) {
mtx_unlock(&ktrace_mtx);
req = malloc(sizeof(struct ktr_request), M_KTRACE,
M_WAITOK);
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
ktr_requestpool++;
}
return (ktr_requestpool);
}
static struct ktr_request *
ktr_getrequest(int type)
{
struct ktr_request *req;
struct thread *td = curthread;
struct proc *p = td->td_proc;
int pm;
td->td_inktrace = 1;
mtx_lock(&ktrace_mtx);
if (!KTRCHECK(td, type)) {
mtx_unlock(&ktrace_mtx);
td->td_inktrace = 0;
return (NULL);
}
req = STAILQ_FIRST(&ktr_free);
if (req != NULL) {
STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
req->ktr_header.ktr_type = type;
KASSERT(p->p_tracep != NULL, ("ktrace: no trace vnode"));
req->ktr_vp = p->p_tracep;
VREF(p->p_tracep);
mtx_unlock(&ktrace_mtx);
microtime(&req->ktr_header.ktr_time);
req->ktr_header.ktr_pid = p->p_pid;
bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1);
req->ktr_cred = crhold(td->td_ucred);
req->ktr_header.ktr_buffer = NULL;
req->ktr_header.ktr_len = 0;
req->ktr_synchronous = 0;
} else {
pm = print_message;
print_message = 0;
mtx_unlock(&ktrace_mtx);
if (pm)
printf("Out of ktrace request objects.\n");
td->td_inktrace = 0;
}
return (req);
}
static void
ktr_submitrequest(struct ktr_request *req)
{
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_TAIL(&ktr_todo, req, ktr_list);
sema_post(&ktrace_sema);
if (req->ktr_synchronous) {
/*
* For a synchronous request, we wait for the ktrace thread
* to get to our item in the todo list and wake us up. Then
* we write the request out ourselves and wake the ktrace
* thread back up.
*/
msleep(req, &ktrace_mtx, curthread->td_priority, "ktrsync", 0);
mtx_unlock(&ktrace_mtx);
ktr_writerequest(req);
mtx_lock(&ktrace_mtx);
wakeup(req);
}
mtx_unlock(&ktrace_mtx);
curthread->td_inktrace = 0;
}
static void
ktr_freerequest(struct ktr_request *req)
{
crfree(req->ktr_cred);
mtx_lock(&Giant);
vrele(req->ktr_vp);
mtx_unlock(&Giant);
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
mtx_unlock(&ktrace_mtx);
}
static void
ktr_loop(void *dummy)
{
struct ktr_request *req;
struct thread *td;
struct ucred *cred;
/* Only cache these values once. */
td = curthread;
cred = td->td_ucred;
for (;;) {
sema_wait(&ktrace_sema);
mtx_lock(&ktrace_mtx);
req = STAILQ_FIRST(&ktr_todo);
STAILQ_REMOVE_HEAD(&ktr_todo, ktr_list);
KASSERT(req != NULL, ("got a NULL request"));
if (req->ktr_synchronous) {
wakeup(req);
msleep(req, &ktrace_mtx, curthread->td_priority,
"ktrwait", 0);
mtx_unlock(&ktrace_mtx);
} else {
mtx_unlock(&ktrace_mtx);
/*
* It is not enough just to pass the cached cred
* to the VOP's in ktr_writerequest(). Some VFS
* operations use curthread->td_ucred, so we need
* to modify our thread's credentials as well.
* Evil.
*/
td->td_ucred = req->ktr_cred;
ktr_writerequest(req);
td->td_ucred = cred;
}
ktr_freerequest(req);
}
}
/*
* MPSAFE
*/
void
ktrsyscall(vp, code, narg, args)
struct vnode *vp;
ktrsyscall(code, narg, args)
int code, narg;
register_t args[];
{
struct ktr_header *kth;
struct ktr_syscall *ktp;
register int len = offsetof(struct ktr_syscall, ktr_args) +
(narg * sizeof(register_t));
struct proc *p = curproc; /* XXX */
register_t *argp;
int i;
struct ktr_request *req;
struct ktr_syscall *ktp;
size_t buflen;
mtx_lock(&Giant);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_SYSCALL);
MALLOC(ktp, struct ktr_syscall *, len, M_KTRACE, M_WAITOK);
req = ktr_getrequest(KTR_SYSCALL);
if (req == NULL)
return;
ktp = &req->ktr_data.ktr_syscall;
ktp->ktr_code = code;
ktp->ktr_narg = narg;
argp = &ktp->ktr_args[0];
for (i = 0; i < narg; i++)
*argp++ = args[i];
kth->ktr_buffer = (caddr_t)ktp;
kth->ktr_len = len;
ktrwrite(vp, kth, NULL);
FREE(ktp, M_KTRACE);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
mtx_unlock(&Giant);
buflen = sizeof(register_t) * narg;
if (buflen > 0) {
req->ktr_header.ktr_buffer = malloc(buflen, M_KTRACE, M_WAITOK);
bcopy(args, req->ktr_header.ktr_buffer, buflen);
req->ktr_header.ktr_len = buflen;
}
ktr_submitrequest(req);
}
/*
* MPSAFE
*/
void
ktrsysret(vp, code, error, retval)
struct vnode *vp;
ktrsysret(code, error, retval)
int code, error;
register_t retval;
{
struct ktr_header *kth;
struct ktr_sysret ktp;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
struct ktr_sysret *ktp;
mtx_lock(&Giant);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_SYSRET);
ktp.ktr_code = code;
ktp.ktr_error = error;
ktp.ktr_retval = retval; /* what about val2 ? */
kth->ktr_buffer = (caddr_t)&ktp;
kth->ktr_len = sizeof(struct ktr_sysret);
ktrwrite(vp, kth, NULL);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
mtx_unlock(&Giant);
req = ktr_getrequest(KTR_SYSRET);
if (req == NULL)
return;
ktp = &req->ktr_data.ktr_sysret;
ktp->ktr_code = code;
ktp->ktr_error = error;
ktp->ktr_retval = retval; /* what about val2 ? */
ktr_submitrequest(req);
}
void
ktrnamei(vp, path)
struct vnode *vp;
ktrnamei(path)
char *path;
{
struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
int namelen;
/*
* don't let p_tracep get ripped out from under us
*/
if (vp)
VREF(vp);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_NAMEI);
kth->ktr_len = strlen(path);
kth->ktr_buffer = path;
ktrwrite(vp, kth, NULL);
if (vp)
vrele(vp);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
req = ktr_getrequest(KTR_NAMEI);
if (req == NULL)
return;
namelen = strlen(path);
if (namelen > 0) {
req->ktr_header.ktr_len = namelen;
req->ktr_header.ktr_buffer = malloc(namelen, M_KTRACE,
M_WAITOK);
bcopy(path, req->ktr_header.ktr_buffer, namelen);
}
ktr_submitrequest(req);
}
/*
* Since the uio may not stay valid, we can not hand off this request to
* the thread and need to process it synchronously. However, we wish to
* keep the relative order of records in a trace file correct, so we
* do put this request on the queue (if it isn't empty) and then block.
* The ktrace thread waks us back up when it is time for this event to
* be posted and blocks until we have completed writing out the event
* and woken it back up.
*/
void
ktrgenio(vp, fd, rw, uio, error)
struct vnode *vp;
ktrgenio(fd, rw, uio, error)
int fd;
enum uio_rw rw;
struct uio *uio;
int error;
{
struct ktr_header *kth;
struct ktr_genio ktg;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
struct ktr_genio *ktg;
if (error)
return;
mtx_lock(&Giant);
/*
* don't let p_tracep get ripped out from under us
*/
if (vp)
VREF(vp);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_GENIO);
ktg.ktr_fd = fd;
ktg.ktr_rw = rw;
kth->ktr_buffer = (caddr_t)&ktg;
kth->ktr_len = sizeof(struct ktr_genio);
req = ktr_getrequest(KTR_GENIO);
if (req == NULL)
return;
ktg = &req->ktr_data.ktr_genio;
ktg->ktr_fd = fd;
ktg->ktr_rw = rw;
req->ktr_header.ktr_buffer = uio;
uio->uio_offset = 0;
uio->uio_rw = UIO_WRITE;
ktrwrite(vp, kth, uio);
if (vp)
vrele(vp);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
mtx_unlock(&Giant);
req->ktr_synchronous = 1;
ktr_submitrequest(req);
}
void
ktrpsig(vp, sig, action, mask, code)
struct vnode *vp;
ktrpsig(sig, action, mask, code)
int sig;
sig_t action;
sigset_t *mask;
int code;
{
struct ktr_header *kth;
struct ktr_psig kp;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
struct ktr_psig *kp;
/*
* don't let vp get ripped out from under us
*/
if (vp)
VREF(vp);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_PSIG);
kp.signo = (char)sig;
kp.action = action;
kp.mask = *mask;
kp.code = code;
kth->ktr_buffer = (caddr_t)&kp;
kth->ktr_len = sizeof (struct ktr_psig);
ktrwrite(vp, kth, NULL);
if (vp)
vrele(vp);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
req = ktr_getrequest(KTR_PSIG);
if (req == NULL)
return;
kp = &req->ktr_data.ktr_psig;
kp->signo = (char)sig;
kp->action = action;
kp->mask = *mask;
kp->code = code;
ktr_submitrequest(req);
}
void
ktrcsw(vp, out, user)
struct vnode *vp;
ktrcsw(out, user)
int out, user;
{
struct ktr_header *kth;
struct ktr_csw kc;
struct proc *p = curproc; /* XXX */
struct ktr_request *req;
struct ktr_csw *kc;
/*
* don't let vp get ripped out from under us
*/
if (vp)
VREF(vp);
p->p_traceflag |= KTRFAC_ACTIVE;
kth = ktrgetheader(KTR_CSW);
kc.out = out;
kc.user = user;
kth->ktr_buffer = (caddr_t)&kc;
kth->ktr_len = sizeof (struct ktr_csw);
ktrwrite(vp, kth, NULL);
if (vp)
vrele(vp);
FREE(kth, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
req = ktr_getrequest(KTR_CSW);
if (req == NULL)
return;
kc = &req->ktr_data.ktr_csw;
kc->out = out;
kc->user = user;
ktr_submitrequest(req);
}
#endif
@ -287,7 +475,6 @@ ktrace(td, uap)
register struct ktrace_args *uap;
{
#ifdef KTRACE
struct proc *curp = td->td_proc;
register struct vnode *vp = NULL;
register struct proc *p;
struct pgrp *pg;
@ -298,7 +485,7 @@ ktrace(td, uap)
int flags, error = 0;
struct nameidata nd;
curp->p_traceflag |= KTRFAC_ACTIVE;
td->td_inktrace = 1;
if (ops != KTROP_CLEAR) {
/*
* an operation which requires a file argument.
@ -307,7 +494,7 @@ ktrace(td, uap)
flags = FREAD | FWRITE | O_NOFOLLOW;
error = vn_open(&nd, &flags, 0);
if (error) {
curp->p_traceflag &= ~KTRFAC_ACTIVE;
td->td_inktrace = 0;
return (error);
}
NDFREE(&nd, NDF_ONLY_PNBUF);
@ -315,7 +502,7 @@ ktrace(td, uap)
VOP_UNLOCK(vp, 0, td);
if (vp->v_type != VREG) {
(void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
curp->p_traceflag &= ~KTRFAC_ACTIVE;
td->td_inktrace = 0;
return (EACCES);
}
}
@ -327,9 +514,11 @@ ktrace(td, uap)
LIST_FOREACH(p, &allproc, p_list) {
PROC_LOCK(p);
if (p->p_tracep == vp) {
if (ktrcanset(td, p) && p->p_tracep == vp) {
if (ktrcanset(td, p)) {
mtx_lock(&ktrace_mtx);
p->p_tracep = NULL;
p->p_traceflag = 0;
mtx_unlock(&ktrace_mtx);
PROC_UNLOCK(p);
(void) vn_close(vp, FREAD|FWRITE,
td->td_ucred, td);
@ -396,7 +585,7 @@ ktrace(td, uap)
done:
if (vp != NULL)
(void) vn_close(vp, FWRITE, td->td_ucred, td);
curp->p_traceflag &= ~KTRFAC_ACTIVE;
td->td_inktrace = 0;
return (error);
#else
return ENOSYS;
@ -414,31 +603,23 @@ utrace(td, uap)
{
#ifdef KTRACE
struct ktr_header *kth;
struct proc *p = curproc; /* XXX */
struct vnode *vp;
struct ktr_request *req;
register caddr_t cp;
if (!KTRPOINT(p, KTR_USER))
return (0);
if (uap->len > KTR_USER_MAXLEN)
return (EINVAL);
p->p_traceflag |= KTRFAC_ACTIVE;
if ((vp = p->p_tracep) != NULL)
VREF(vp);
kth = ktrgetheader(KTR_USER);
req = ktr_getrequest(KTR_USER);
if (req == NULL)
return (0);
MALLOC(cp, caddr_t, uap->len, M_KTRACE, M_WAITOK);
if (!copyin(uap->addr, cp, uap->len)) {
kth->ktr_buffer = cp;
kth->ktr_len = uap->len;
ktrwrite(vp, kth, NULL);
req->ktr_header.ktr_buffer = cp;
req->ktr_header.ktr_len = uap->len;
ktr_submitrequest(req);
} else {
ktr_freerequest(req);
td->td_inktrace = 0;
}
if (vp)
vrele(vp);
FREE(kth, M_KTRACE);
FREE(cp, M_KTRACE);
p->p_traceflag &= ~KTRFAC_ACTIVE;
return (0);
#else
return (ENOSYS);
@ -453,23 +634,22 @@ ktrops(td, p, ops, facs, vp)
int ops, facs;
struct vnode *vp;
{
struct vnode *vtmp = NULL, *newvp = NULL;
struct vnode *tracevp = NULL;
PROC_LOCK(p);
if (!ktrcanset(td, p)) {
PROC_UNLOCK(p);
return (0);
}
mtx_lock(&ktrace_mtx);
if (ops == KTROP_SET) {
if (p->p_tracep != vp) {
struct vnode *vtmp;
/*
* if trace file already in use, relinquish below
*/
newvp = vp;
vtmp = p->p_tracep;
p->p_tracep = NULL;
tracevp = p->p_tracep;
VREF(vp);
p->p_tracep = vp;
}
p->p_traceflag |= facs;
if (td->td_ucred->cr_uid == 0)
@ -477,33 +657,17 @@ ktrops(td, p, ops, facs, vp)
} else {
/* KTROP_CLEAR */
if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
struct vnode *vtmp;
/* no more tracing */
p->p_traceflag = 0;
vtmp = p->p_tracep;
tracevp = p->p_tracep;
p->p_tracep = NULL;
}
}
mtx_unlock(&ktrace_mtx);
PROC_UNLOCK(p);
if (tracevp != NULL)
vrele(tracevp);
/* Release old trace file if requested. */
if (vtmp != NULL)
vrele(vtmp);
/* Setup new trace file if requested. */
/*
* XXX: Doing this before the PROC_UNLOCK above would result in
* fewer lock operations but would break old behavior where the
* above vrele() would not be traced when changing trace files.
*/
if (newvp != NULL) {
VREF(newvp);
PROC_LOCK(p);
p->p_tracep = newvp;
PROC_UNLOCK(p);
}
return (1);
}
@ -544,20 +708,32 @@ ktrsetchildren(td, top, ops, facs, vp)
}
static void
ktrwrite(vp, kth, uio)
struct vnode *vp;
register struct ktr_header *kth;
struct uio *uio;
ktr_writerequest(struct ktr_request *req)
{
struct ktr_header *kth;
struct vnode *vp;
struct uio *uio = NULL;
struct proc *p;
struct thread *td;
struct ucred *cred;
struct uio auio;
struct iovec aiov[2];
struct thread *td = curthread; /* XXX */
struct proc *p = td->td_proc; /* XXX */
struct iovec aiov[3];
struct mount *mp;
int datalen, buflen, vrele_count;
int error;
vp = req->ktr_vp;
/*
* If vp is NULL, the vp has been cleared out from under this
* request, so just drop it.
*/
if (vp == NULL)
return;
kth = &req->ktr_header;
datalen = data_lengths[kth->ktr_type];
buflen = kth->ktr_len;
cred = req->ktr_cred;
td = curthread;
auio.uio_iov = &aiov[0];
auio.uio_offset = 0;
auio.uio_segflg = UIO_SYSSPACE;
@ -566,42 +742,85 @@ ktrwrite(vp, kth, uio)
aiov[0].iov_len = sizeof(struct ktr_header);
auio.uio_resid = sizeof(struct ktr_header);
auio.uio_iovcnt = 1;
auio.uio_td = curthread;
if (kth->ktr_len > 0) {
auio.uio_td = td;
if (datalen != 0) {
aiov[1].iov_base = (caddr_t)&req->ktr_data;
aiov[1].iov_len = datalen;
auio.uio_resid += datalen;
auio.uio_iovcnt++;
aiov[1].iov_base = kth->ktr_buffer;
aiov[1].iov_len = kth->ktr_len;
auio.uio_resid += kth->ktr_len;
if (uio != NULL)
kth->ktr_len += uio->uio_resid;
kth->ktr_len += datalen;
}
if (buflen != 0) {
KASSERT(kth->ktr_buffer != NULL, ("ktrace: nothing to write"));
aiov[auio.uio_iovcnt].iov_base = kth->ktr_buffer;
aiov[auio.uio_iovcnt].iov_len = buflen;
auio.uio_resid += buflen;
auio.uio_iovcnt++;
} else
uio = kth->ktr_buffer;
KASSERT((uio == NULL) ^ (kth->ktr_type == KTR_GENIO),
("ktrace: uio and genio mismatch"));
if (uio != NULL)
kth->ktr_len += uio->uio_resid;
mtx_lock(&Giant);
vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
(void)VOP_LEASE(vp, td, td->td_ucred, LEASE_WRITE);
error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, td->td_ucred);
(void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
if (error == 0 && uio != NULL) {
(void)VOP_LEASE(vp, td, td->td_ucred, LEASE_WRITE);
error = VOP_WRITE(vp, uio, IO_UNIT | IO_APPEND, td->td_ucred);
(void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
error = VOP_WRITE(vp, uio, IO_UNIT | IO_APPEND, cred);
}
VOP_UNLOCK(vp, 0, td);
vn_finished_write(mp);
mtx_unlock(&Giant);
if (buflen != 0)
free(kth->ktr_buffer, M_KTRACE);
if (!error)
return;
/*
* If error encountered, give up tracing on this vnode. XXX what
* happens to the loop if vrele() blocks?
* If error encountered, give up tracing on this vnode. We defer
* all the vrele()'s on the vnode until after we are finished walking
* the various lists to avoid needlessly holding locks.
*/
log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
error);
vrele_count = 0;
/*
* First, clear this vnode from being used by any processes in the
* system.
* XXX - If one process gets an EPERM writing to the vnode, should
* we really do this? Other processes might have suitable
* credentials for the operation.
*/
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
PROC_LOCK(p);
if (p->p_tracep == vp) {
mtx_lock(&ktrace_mtx);
p->p_tracep = NULL;
p->p_traceflag = 0;
vrele(vp);
mtx_unlock(&ktrace_mtx);
vrele_count++;
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
/*
* Second, clear this vnode from any pending requests.
*/
mtx_lock(&ktrace_mtx);
STAILQ_FOREACH(req, &ktr_todo, ktr_list) {
if (req->ktr_vp == vp) {
req->ktr_vp = NULL;
vrele_count++;
}
}
mtx_unlock(&ktrace_mtx);
mtx_lock(&Giant);
while (vrele_count-- > 0)
vrele(vp);
mtx_unlock(&Giant);
}
/*

28
sys/sys/ktrace.h
View File

@ -58,14 +58,19 @@ struct ktr_header {
pid_t ktr_pid; /* process id */
char ktr_comm[MAXCOMLEN+1]; /* command name */
struct timeval ktr_time; /* timestamp */
caddr_t ktr_buffer;
void *ktr_buffer;
};
/*
* Test for kernel trace point (MP SAFE)
* Test for kernel trace point (MP SAFE).
*
* KTRCHECK() just checks that the type is enabled and is only for
* internal use in the ktrace subsystem. KTRPOINT() checks against
* ktrace recursion as well as checking that the type is enabled and
* is the public interface.
*/
#define KTRPOINT(p, type) \
(((p)->p_traceflag & ((1<<(type))|KTRFAC_ACTIVE)) == (1<<(type)))
#define KTRCHECK(td, type) ((td)->td_proc->p_traceflag & (1 << type))
#define KTRPOINT(td, type) (KTRCHECK((td), (type)) && !(td)->td_inktrace)
/*
* ktrace record types
@ -155,15 +160,16 @@ struct ktr_csw {
*/
#define KTRFAC_ROOT 0x80000000 /* root set this trace */
#define KTRFAC_INHERIT 0x40000000 /* pass trace flags to children */
#define KTRFAC_ACTIVE 0x20000000 /* ktrace logging in progress, ignore */
#ifdef _KERNEL
void ktrnamei(struct vnode *,char *);
void ktrcsw(struct vnode *,int,int);
void ktrpsig(struct vnode *, int, sig_t, sigset_t *, int);
void ktrgenio(struct vnode *, int, enum uio_rw, struct uio *, int);
void ktrsyscall(struct vnode *, int, int narg, register_t args[]);
void ktrsysret(struct vnode *, int, int, register_t);
extern struct mtx ktrace_mtx;
void ktrnamei(char *);
void ktrcsw(int, int);
void ktrpsig(int, sig_t, sigset_t *, int);
void ktrgenio(int, enum uio_rw, struct uio *, int);
void ktrsyscall(int, int narg, register_t args[]);
void ktrsysret(int, int, register_t);
#else