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fasttrap.c
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2786 lines (2389 loc) · 70.5 KB
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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.
*/
//#pragma ident "@(#)fasttrap.c 1.26 08/04/21 SMI"
# if linux
#include "dtrace_linux.h"
#include "proc_compat.h"
#include <sys/zone.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <sys/fasttrap.h>
#include <sys/fasttrap_impl.h>
#include <sys/fasttrap_isa.h>
#include <sys/dtrace.h>
#include <sys/dtrace_impl.h>
#include <sys/rwlock.h>
#include "dtrace_proto.h"
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 16)
void sort(void *base, size_t num, size_t size,
int (*cmp)(const void *, const void *),
void (*swap)(void *, void *, int));
#else
# include <linux/sort.h>
#endif
#include <linux/module.h>
extern int nr_cpus;
// Temporary definitions so we can compile.
proc_t *
sprlock(int pid)
{
proc_t *p = prfind(pid);
//printk("sprlock: pid=%d\n", pid);
if (!p)
return NULL;
dmutex_enter(&p->p_lock);
return p;
}
void
sprlock_proc(proc_t *p)
{
dmutex_enter(&p->p_lock);
}
void
sprunlock(proc_t *p)
{
dmutex_exit(&p->p_lock);
}
# define RW_WRITER 2
#define SEXITING 0x00000002 /* process is exiting */
#define SFORKING 0x00000008 /* tells called functions that we're forking */
#define SVFORK 0x00040000 /* child of vfork that has not yet exec'd */
#define VREAD 00400
#define VWRITE 00200
# define priv_proc_cred_perm(cr, p, ptr, flags) 0
static void swap_func(void *p1, void *p2, int size)
{
while (size-- > 0) {
char t = *(char *) p1;
*(char *) p1 = *(char *) p2;
*(char *) p2 = t;
p1 = p1 + 1;
p2 = p2 + 1;
}
}
# define qsort(base, num, size, cmp) sort(base, num, size, cmp, swap_func)
MUTEX_DEFINE(pidlock);
void (*dtrace_fasttrap_fork_ptr)(proc_t *, proc_t *);
void (*dtrace_fasttrap_exec_ptr)(proc_t *);
void (*dtrace_fasttrap_exit_ptr)(proc_t *);
# endif
# if defined(sun)
#include <sys/atomic.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/modctl.h>
#include <sys/conf.h>
#include <sys/systm.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/cpuvar.h>
#include <sys/kmem.h>
#include <sys/strsubr.h>
#include <sys/fasttrap.h>
#include <sys/fasttrap_impl.h>
#include <sys/fasttrap_isa.h>
#include <sys/dtrace.h>
#include <sys/dtrace_impl.h>
#include <sys/sysmacros.h>
#include <sys/frame.h>
#include <sys/stack.h>
#include <sys/proc.h>
#include <sys/priv.h>
#include <sys/policy.h>
#include <sys/ontrap.h>
#include <sys/vmsystm.h>
#include <sys/prsystm.h>
#include <vm/as.h>
#include <vm/seg.h>
#include <vm/seg_dev.h>
#include <vm/seg_vn.h>
#include <vm/seg_spt.h>
#include <vm/seg_kmem.h>
# endif
/*
* User-Land Trap-Based Tracing
* ----------------------------
*
* The fasttrap provider allows DTrace consumers to instrument any user-level
* instruction to gather data; this includes probes with semantic
* signifigance like entry and return as well as simple offsets into the
* function. While the specific techniques used are very ISA specific, the
* methodology is generalizable to any architecture.
*
*
* The General Methodology
* -----------------------
*
* With the primary goal of tracing every user-land instruction and the
* limitation that we can't trust user space so don't want to rely on much
* information there, we begin by replacing the instructions we want to trace
* with trap instructions. Each instruction we overwrite is saved into a hash
* table keyed by process ID and pc address. When we enter the kernel due to
* this trap instruction, we need the effects of the replaced instruction to
* appear to have occurred before we proceed with the user thread's
* execution.
*
* Each user level thread is represented by a ulwp_t structure which is
* always easily accessible through a register. The most basic way to produce
* the effects of the instruction we replaced is to copy that instruction out
* to a bit of scratch space reserved in the user thread's ulwp_t structure
* (a sort of kernel-private thread local storage), set the PC to that
* scratch space and single step. When we reenter the kernel after single
* stepping the instruction we must then adjust the PC to point to what would
* normally be the next instruction. Of course, special care must be taken
* for branches and jumps, but these represent such a small fraction of any
* instruction set that writing the code to emulate these in the kernel is
* not too difficult.
*
* Return probes may require several tracepoints to trace every return site,
* and, conversely, each tracepoint may activate several probes (the entry
* and offset 0 probes, for example). To solve this muliplexing problem,
* tracepoints contain lists of probes to activate and probes contain lists
* of tracepoints to enable. If a probe is activated, it adds its ID to
* existing tracepoints or creates new ones as necessary.
*
* Most probes are activated _before_ the instruction is executed, but return
* probes are activated _after_ the effects of the last instruction of the
* function are visible. Return probes must be fired _after_ we have
* single-stepped the instruction whereas all other probes are fired
* beforehand.
*
*
* Lock Ordering
* -------------
*
* The lock ordering below -- both internally and with respect to the DTrace
* framework -- is a little tricky and bears some explanation. Each provider
* has a lock (ftp_mtx) that protects its members including reference counts
* for enabled probes (ftp_rcount), consumers actively creating probes
* (ftp_ccount) and USDT consumers (ftp_mcount); all three prevent a provider
* from being freed. A provider is looked up by taking the bucket lock for the
* provider hash table, and is returned with its lock held. The provider lock
* may be taken in functions invoked by the DTrace framework, but may not be
* held while calling functions in the DTrace framework.
*
* To ensure consistency over multiple calls to the DTrace framework, the
* creation lock (ftp_cmtx) should be held. Naturally, the creation lock may
* not be taken when holding the provider lock as that would create a cyclic
* lock ordering. In situations where one would naturally take the provider
* lock and then the creation lock, we instead up a reference count to prevent
* the provider from disappearing, drop the provider lock, and acquire the
* creation lock.
*
* Briefly:
* bucket lock before provider lock
* DTrace before provider lock
* creation lock before DTrace
* never hold the provider lock and creation lock simultaneously
*/
# if defined(sun)
static dev_info_t *fasttrap_devi;
# endif
static dtrace_meta_provider_id_t fasttrap_meta_id;
static timeout_id_t fasttrap_timeout;
static MUTEX_DEFINE(fasttrap_cleanup_mtx);
static uint_t fasttrap_cleanup_work;
/*
* Generation count on modifications to the global tracepoint lookup table.
*/
static volatile uint64_t fasttrap_mod_gen;
/*
* When the fasttrap provider is loaded, fasttrap_max is set to either
* FASTTRAP_MAX_DEFAULT or the value for fasttrap-max-probes in the
* fasttrap.conf file. Each time a probe is created, fasttrap_total is
* incremented by the number of tracepoints that may be associated with that
* probe; fasttrap_total is capped at fasttrap_max.
*/
#define FASTTRAP_MAX_DEFAULT 250000
# if defined(sun)
static uint32_t fasttrap_max;
# else
uint32_t fasttrap_max;
module_param(fasttrap_max, int, 0);
# endif
static uint32_t fasttrap_total;
#define FASTTRAP_TPOINTS_DEFAULT_SIZE 0x4000
#define FASTTRAP_PROVIDERS_DEFAULT_SIZE 0x100
#define FASTTRAP_PROCS_DEFAULT_SIZE 0x100
#define FASTTRAP_PID_NAME "pid"
fasttrap_hash_t fasttrap_tpoints;
static fasttrap_hash_t fasttrap_provs;
static fasttrap_hash_t fasttrap_procs;
static uint64_t fasttrap_pid_count; /* pid ref count */
static MUTEX_DEFINE(fasttrap_count_mtx); /* lock on ref count */
#define FASTTRAP_ENABLE_FAIL 1
#define FASTTRAP_ENABLE_PARTIAL 2
static int fasttrap_tracepoint_enable(proc_t *, fasttrap_probe_t *, uint_t);
static void fasttrap_tracepoint_disable(proc_t *, fasttrap_probe_t *, uint_t);
static fasttrap_provider_t *fasttrap_provider_lookup(pid_t, const char *,
const dtrace_pattr_t *);
static void fasttrap_provider_retire(pid_t, const char *, int);
static void fasttrap_provider_free(fasttrap_provider_t *);
static fasttrap_proc_t *fasttrap_proc_lookup(pid_t);
static void fasttrap_proc_release(fasttrap_proc_t *);
#define FASTTRAP_PROVS_INDEX(pid, name) \
((fasttrap_hash_str(name) + (pid)) & fasttrap_provs.fth_mask)
#define FASTTRAP_PROCS_INDEX(pid) ((pid) & fasttrap_procs.fth_mask)
static int
fasttrap_highbit(ulong_t i)
{
int h = 1;
if (i == 0)
return (0);
#ifdef _LP64
if (i & 0xffffffff00000000ul) {
h += 32; i >>= 32;
}
#endif
if (i & 0xffff0000) {
h += 16; i >>= 16;
}
if (i & 0xff00) {
h += 8; i >>= 8;
}
if (i & 0xf0) {
h += 4; i >>= 4;
}
if (i & 0xc) {
h += 2; i >>= 2;
}
if (i & 0x2) {
h += 1;
}
return (h);
}
static uint_t
fasttrap_hash_str(const char *p)
{
unsigned int g;
uint_t hval = 0;
while (*p) {
hval = (hval << 4) + *p++;
if ((g = (hval & 0xf0000000)) != 0)
hval ^= g >> 24;
hval &= ~g;
}
return (hval);
}
void
fasttrap_sigtrap(proc_t *p, proc_t *t, uintptr_t pc)
{
# if defined(sun)
sigqueue_t *sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
HERE();
sqp->sq_info.si_signo = SIGTRAP;
sqp->sq_info.si_code = TRAP_DTRACE;
sqp->sq_info.si_addr = (caddr_t)pc;
dmutex_enter(&p->p_lock);
sigaddqa(p, t, sqp);
dmutex_exit(&p->p_lock);
if (t != NULL)
aston(t);
# else
TODO();
send_sig(SIGTRAP, p->p_task, 0);
# endif
}
/*
* This function ensures that no threads are actively using the memory
* associated with probes that were formerly live.
*/
static void
fasttrap_mod_barrier(uint64_t gen)
{
int i;
if (gen < fasttrap_mod_gen)
return;
fasttrap_mod_gen++;
/***********************************************/
/* Need to fix this - we need to ensure */
/* this is really a memory barrier. */
/***********************************************/
HERE();
/***********************************************/
/* Be careful if we have new cpus coming */
/* online after we got loaded since the */
/* cpu_core[] array wont have the right */
/* number of entries and we may panic the */
/* kernel. */
/***********************************************/
for (i = 0; i < num_online_cpus(); i++) {
dmutex_enter(&cpu_core[i].cpuc_pid_lock);
dmutex_exit(&cpu_core[i].cpuc_pid_lock);
HERE();
}
}
/*
* This is the timeout's callback for cleaning up the providers and their
* probes.
*/
/*ARGSUSED*/
static void
fasttrap_pid_cleanup_cb(void *data)
{
fasttrap_provider_t **fpp, *fp;
fasttrap_bucket_t *bucket;
dtrace_provider_id_t provid;
int i, later = 0;
static volatile int in = 0;
ASSERT(in == 0);
in = 1;
HERE();
dmutex_enter(&fasttrap_cleanup_mtx);
while (fasttrap_cleanup_work) {
fasttrap_cleanup_work = 0;
dmutex_exit(&fasttrap_cleanup_mtx);
later = 0;
/*
* Iterate over all the providers trying to remove the marked
* ones. If a provider is marked but not retired, we just
* have to take a crack at removing it -- it's no big deal if
* we can't.
*/
for (i = 0; i < fasttrap_provs.fth_nent; i++) {
bucket = &fasttrap_provs.fth_table[i];
dmutex_enter(&bucket->ftb_mtx);
fpp = (fasttrap_provider_t **)&bucket->ftb_data;
while ((fp = *fpp) != NULL) {
if (!fp->ftp_marked) {
fpp = &fp->ftp_next;
continue;
}
dmutex_enter(&fp->ftp_mtx);
/*
* If this provider has consumers actively
* creating probes (ftp_ccount) or is a USDT
* provider (ftp_mcount), we can't unregister
* or even condense.
*/
if (fp->ftp_ccount != 0 ||
fp->ftp_mcount != 0) {
dmutex_exit(&fp->ftp_mtx);
fp->ftp_marked = 0;
continue;
}
if (!fp->ftp_retired || fp->ftp_rcount != 0)
fp->ftp_marked = 0;
dmutex_exit(&fp->ftp_mtx);
/*
* If we successfully unregister this
* provider we can remove it from the hash
* chain and free the memory. If our attempt
* to unregister fails and this is a retired
* provider, increment our flag to try again
* pretty soon. If we've consumed more than
* half of our total permitted number of
* probes call dtrace_condense() to try to
* clean out the unenabled probes.
*/
provid = fp->ftp_provid;
if (dtrace_unregister(provid) != 0) {
if (fasttrap_total > fasttrap_max / 2)
(void) dtrace_condense(provid);
later += fp->ftp_marked;
fpp = &fp->ftp_next;
} else {
*fpp = fp->ftp_next;
fasttrap_provider_free(fp);
}
}
dmutex_exit(&bucket->ftb_mtx);
}
dmutex_enter(&fasttrap_cleanup_mtx);
}
ASSERT(fasttrap_timeout != 0);
/*
* If we were unable to remove a retired provider, try again after
* a second. This situation can occur in certain circumstances where
* providers cannot be unregistered even though they have no probes
* enabled because of an execution of dtrace -l or something similar.
* If the timeout has been disabled (set to 1 because we're trying
* to detach), we set fasttrap_cleanup_work to ensure that we'll
* get a chance to do that work if and when the timeout is reenabled
* (if detach fails).
*/
if (later > 0 && fasttrap_timeout != (timeout_id_t)1)
fasttrap_timeout = timeout(&fasttrap_pid_cleanup_cb, NULL, hz);
else if (later > 0)
fasttrap_cleanup_work = 1;
else
fasttrap_timeout = 0;
dmutex_exit(&fasttrap_cleanup_mtx);
in = 0;
}
/*
* Activates the asynchronous cleanup mechanism.
*/
static void
fasttrap_pid_cleanup(void)
{
HERE();
dmutex_enter(&fasttrap_cleanup_mtx);
fasttrap_cleanup_work = 1;
if (fasttrap_timeout == 0)
fasttrap_timeout = timeout(&fasttrap_pid_cleanup_cb, NULL, 1);
dmutex_exit(&fasttrap_cleanup_mtx);
}
/*
* This is called from cfork() via dtrace_fasttrap_fork(). The child
* process's address space is (roughly) a copy of the parent process's so
* we have to remove all the instrumentation we had previously enabled in the
* parent.
*/
static void
fasttrap_fork(proc_t *p, proc_t *cp)
{
pid_t ppid = p->p_pid;
int i;
printk("in fasttrap_fork\n");
ASSERT(curproc == p);
ASSERT(p->p_proc_flag & P_PR_LOCK);
ASSERT(p->p_dtrace_count > 0);
ASSERT(cp->p_dtrace_count == 0);
/*
* This would be simpler and faster if we maintained per-process
* hash tables of enabled tracepoints. It could, however, potentially
* slow down execution of a tracepoint since we'd need to go
* through two levels of indirection. In the future, we should
* consider either maintaining per-process ancillary lists of
* enabled tracepoints or hanging a pointer to a per-process hash
* table of enabled tracepoints off the proc structure.
*/
/*
* We don't have to worry about the child process disappearing
* because we're in fork().
*/
dmutex_enter(&cp->p_lock);
sprlock_proc(cp);
dmutex_exit(&cp->p_lock);
/*
* Iterate over every tracepoint looking for ones that belong to the
* parent process, and remove each from the child process.
*/
for (i = 0; i < fasttrap_tpoints.fth_nent; i++) {
fasttrap_tracepoint_t *tp;
fasttrap_bucket_t *bucket = &fasttrap_tpoints.fth_table[i];
dmutex_enter(&bucket->ftb_mtx);
for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
if (tp->ftt_pid == ppid &&
tp->ftt_proc->ftpc_acount != 0) {
int ret = fasttrap_tracepoint_remove(cp, tp);
ret = ret; // avoid compiler warning
ASSERT(ret == 0);
/*
* The count of active providers can only be
* decremented (i.e. to zero) during exec,
* exit, and removal of a meta provider so it
* should be impossible to drop the count
* mid-fork.
*/
ASSERT(tp->ftt_proc->ftpc_acount != 0);
}
}
dmutex_exit(&bucket->ftb_mtx);
}
dmutex_enter(&cp->p_lock);
sprunlock(cp);
}
/*
* This is called from proc_exit() or from exec_common() if p_dtrace_probes
* is set on the proc structure to indicate that there is a pid provider
* associated with this process.
*/
static void
fasttrap_exec_exit(proc_t *p)
{
ASSERT(p == curproc);
ASSERT(MUTEX_HELD(&p->p_lock));
dmutex_exit(&p->p_lock);
//printk("fasttrap_exec_exit: pid=%d\n", p->p_pid);
/*
* We clean up the pid provider for this process here; user-land
* static probes are handled by the meta-provider remove entry point.
*/
fasttrap_provider_retire(p->p_pid, FASTTRAP_PID_NAME, 0);
dmutex_enter(&p->p_lock);
}
/*ARGSUSED*/
static void
fasttrap_pid_provide(void *arg, const dtrace_probedesc_t *desc)
{
/*
* There are no "default" pid probes.
*/
}
static int
fasttrap_tracepoint_enable(proc_t *p, fasttrap_probe_t *probe, uint_t index)
{
fasttrap_tracepoint_t *tp, *new_tp = NULL;
fasttrap_bucket_t *bucket;
fasttrap_id_t *id;
pid_t pid;
uintptr_t pc;
ASSERT(index < probe->ftp_ntps);
HERE();
pid = probe->ftp_pid;
pc = probe->ftp_tps[index].fit_tp->ftt_pc;
id = &probe->ftp_tps[index].fit_id;
ASSERT(probe->ftp_tps[index].fit_tp->ftt_pid == pid);
ASSERT(!(p->p_flag & SVFORK));
HERE();
/*
* Before we make any modifications, make sure we've imposed a barrier
* on the generation in which this probe was last modified.
*/
fasttrap_mod_barrier(probe->ftp_gen);
bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
//printk("bucket=%p pid=%d pc=%lx\n", bucket, pid, pc);
HERE();
/*
* If the tracepoint has already been enabled, just add our id to the
* list of interested probes. This may be our second time through
* this path in which case we'll have constructed the tracepoint we'd
* like to install. If we can't find a match, and have an allocated
* tracepoint ready to go, enable that one now.
*
* A tracepoint whose process is defunct is also considered defunct.
* defunct.
*/
again:
dmutex_enter(&bucket->ftb_mtx);
for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
/*
* Note that it's safe to access the active count on the
* associated proc structure because we know that at least one
* provider (this one) will still be around throughout this
* operation.
*/
if (tp->ftt_pid != pid || tp->ftt_pc != pc ||
tp->ftt_proc->ftpc_acount == 0)
continue;
/*
* Now that we've found a matching tracepoint, it would be
* a decent idea to confirm that the tracepoint is still
* enabled and the trap instruction hasn't been overwritten.
* Since this is a little hairy, we'll punt for now.
*/
/*
* This can't be the first interested probe. We don't have
* to worry about another thread being in the midst of
* deleting this tracepoint (which would be the only valid
* reason for a tracepoint to have no interested probes)
* since we're holding P_PR_LOCK for this process.
*/
ASSERT(tp->ftt_ids != NULL || tp->ftt_retids != NULL);
HERE();
switch (id->fti_ptype) {
case DTFTP_ENTRY:
case DTFTP_OFFSETS:
case DTFTP_IS_ENABLED:
id->fti_next = tp->ftt_ids;
membar_producer();
tp->ftt_ids = id;
membar_producer();
break;
case DTFTP_RETURN:
case DTFTP_POST_OFFSETS:
id->fti_next = tp->ftt_retids;
membar_producer();
tp->ftt_retids = id;
membar_producer();
break;
default:
ASSERT(0);
}
HERE();
dmutex_exit(&bucket->ftb_mtx);
HERE();
if (new_tp != NULL) {
new_tp->ftt_ids = NULL;
new_tp->ftt_retids = NULL;
}
return (0);
}
/*
* If we have a good tracepoint ready to go, install it now while
* we have the lock held and no one can screw with us.
*/
HERE();
if (new_tp != NULL) {
int rc = 0;
new_tp->ftt_next = bucket->ftb_data;
membar_producer();
bucket->ftb_data = new_tp;
membar_producer();
dmutex_exit(&bucket->ftb_mtx);
/*
* Activate the tracepoint in the ISA-specific manner.
* If this fails, we need to report the failure, but
* indicate that this tracepoint must still be disabled
* by calling fasttrap_tracepoint_disable().
*/
HERE();
if (fasttrap_tracepoint_install(p, new_tp) != 0) {
rc = FASTTRAP_ENABLE_PARTIAL;
printk("rc=%d FASTTRAP_ENABLE_PARTIAL=%d pc=%p\n", rc, FASTTRAP_ENABLE_PARTIAL, (void *) tp->ftt_pc);
}
HERE();
/*
* Increment the count of the number of tracepoints active in
* the victim process.
*/
ASSERT(p->p_proc_flag & P_PR_LOCK);
p->p_dtrace_count++;
return (rc);
}
HERE();
dmutex_exit(&bucket->ftb_mtx);
/*
* Initialize the tracepoint that's been preallocated with the probe.
*/
new_tp = probe->ftp_tps[index].fit_tp;
HERE();
ASSERT(new_tp->ftt_pid == pid);
ASSERT(new_tp->ftt_pc == pc);
ASSERT(new_tp->ftt_proc == probe->ftp_prov->ftp_proc);
ASSERT(new_tp->ftt_ids == NULL);
ASSERT(new_tp->ftt_retids == NULL);
switch (id->fti_ptype) {
case DTFTP_ENTRY:
case DTFTP_OFFSETS:
case DTFTP_IS_ENABLED:
id->fti_next = NULL;
new_tp->ftt_ids = id;
break;
case DTFTP_RETURN:
case DTFTP_POST_OFFSETS:
id->fti_next = NULL;
new_tp->ftt_retids = id;
break;
default:
ASSERT(0);
}
/*
* If the ISA-dependent initialization goes to plan, go back to the
* beginning and try to install this freshly made tracepoint.
*/
HERE();
if (fasttrap_tracepoint_init(p, new_tp, pc, id->fti_ptype) == 0)
goto again;
HERE();
new_tp->ftt_ids = NULL;
new_tp->ftt_retids = NULL;
return (FASTTRAP_ENABLE_FAIL);
}
static void
fasttrap_tracepoint_disable(proc_t *p, fasttrap_probe_t *probe, uint_t index)
{
fasttrap_bucket_t *bucket;
fasttrap_provider_t *provider = probe->ftp_prov;
fasttrap_tracepoint_t **pp, *tp;
fasttrap_id_t *id, **idp = NULL;
pid_t pid;
uintptr_t pc;
ASSERT(index < probe->ftp_ntps);
pid = probe->ftp_pid;
pc = probe->ftp_tps[index].fit_tp->ftt_pc;
id = &probe->ftp_tps[index].fit_id;
ASSERT(probe->ftp_tps[index].fit_tp->ftt_pid == pid);
/*
* Find the tracepoint and make sure that our id is one of the
* ones registered with it.
*/
bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
dmutex_enter(&bucket->ftb_mtx);
for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
if (tp->ftt_pid == pid && tp->ftt_pc == pc &&
tp->ftt_proc == provider->ftp_proc)
break;
}
/*
* If we somehow lost this tracepoint, we're in a world of hurt.
*/
ASSERT(tp != NULL);
switch (id->fti_ptype) {
case DTFTP_ENTRY:
case DTFTP_OFFSETS:
case DTFTP_IS_ENABLED:
ASSERT(tp->ftt_ids != NULL);
idp = &tp->ftt_ids;
break;
case DTFTP_RETURN:
case DTFTP_POST_OFFSETS:
ASSERT(tp->ftt_retids != NULL);
idp = &tp->ftt_retids;
break;
default:
ASSERT(0);
}
while ((*idp)->fti_probe != probe) {
idp = &(*idp)->fti_next;
ASSERT(*idp != NULL);
}
id = *idp;
*idp = id->fti_next;
membar_producer();
ASSERT(id->fti_probe == probe);
/*
* If there are other registered enablings of this tracepoint, we're
* all done, but if this was the last probe assocated with this
* this tracepoint, we need to remove and free it.
*/
if (tp->ftt_ids != NULL || tp->ftt_retids != NULL) {
/*
* If the current probe's tracepoint is in use, swap it
* for an unused tracepoint.
*/
if (tp == probe->ftp_tps[index].fit_tp) {
fasttrap_probe_t *tmp_probe;
fasttrap_tracepoint_t **tmp_tp;
uint_t tmp_index;
if (tp->ftt_ids != NULL) {
tmp_probe = tp->ftt_ids->fti_probe;
/* LINTED - alignment */
tmp_index = FASTTRAP_ID_INDEX(tp->ftt_ids);
tmp_tp = &tmp_probe->ftp_tps[tmp_index].fit_tp;
} else {
tmp_probe = tp->ftt_retids->fti_probe;
/* LINTED - alignment */
tmp_index = FASTTRAP_ID_INDEX(tp->ftt_retids);
tmp_tp = &tmp_probe->ftp_tps[tmp_index].fit_tp;
}
ASSERT(*tmp_tp != NULL);
ASSERT(*tmp_tp != probe->ftp_tps[index].fit_tp);
ASSERT((*tmp_tp)->ftt_ids == NULL);
ASSERT((*tmp_tp)->ftt_retids == NULL);
probe->ftp_tps[index].fit_tp = *tmp_tp;
*tmp_tp = tp;
}
dmutex_exit(&bucket->ftb_mtx);
/*
* Tag the modified probe with the generation in which it was
* changed.
*/
probe->ftp_gen = fasttrap_mod_gen;
return;
}
dmutex_exit(&bucket->ftb_mtx);
/*
* We can't safely remove the tracepoint from the set of active
* tracepoints until we've actually removed the fasttrap instruction
* from the process's text. We can, however, operate on this
* tracepoint secure in the knowledge that no other thread is going to
* be looking at it since we hold P_PR_LOCK on the process if it's
* live or we hold the provider lock on the process if it's dead and
* gone.
*/
/*
* We only need to remove the actual instruction if we're looking
* at an existing process
*/
if (p != NULL) {
/*
* If we fail to restore the instruction we need to kill
* this process since it's in a completely unrecoverable
* state.
*/
if (fasttrap_tracepoint_remove(p, tp) != 0)
fasttrap_sigtrap(p, NULL, pc);
/*
* Decrement the count of the number of tracepoints active
* in the victim process.
*/
ASSERT(p->p_proc_flag & P_PR_LOCK);
p->p_dtrace_count--;
}
/*
* Remove the probe from the hash table of active tracepoints.
*/
dmutex_enter(&bucket->ftb_mtx);
pp = (fasttrap_tracepoint_t **)&bucket->ftb_data;
ASSERT(*pp != NULL);
while (*pp != tp) {
pp = &(*pp)->ftt_next;
ASSERT(*pp != NULL);
}
*pp = tp->ftt_next;
membar_producer();
dmutex_exit(&bucket->ftb_mtx);
/*
* Tag the modified probe with the generation in which it was changed.
*/
probe->ftp_gen = fasttrap_mod_gen;
}
static void
fasttrap_enable_callbacks(void)
{
/*
* We don't have to play the rw lock game here because we're
* providing something rather than taking something away --
* we can be sure that no threads have tried to follow this
* function pointer yet.
*/
HERE();
//printk("fasttrap_pid_count=%ld\n", fasttrap_pid_count);
dmutex_enter(&fasttrap_count_mtx);
if (fasttrap_pid_count == 0) {
ASSERT(dtrace_pid_probe_ptr == NULL);
ASSERT(dtrace_return_probe_ptr == NULL);
dtrace_pid_probe_ptr = &fasttrap_pid_probe;
dtrace_return_probe_ptr = &fasttrap_return_probe;
}
ASSERT(dtrace_pid_probe_ptr == &fasttrap_pid_probe);
ASSERT(dtrace_return_probe_ptr == &fasttrap_return_probe);
fasttrap_pid_count++;
dmutex_exit(&fasttrap_count_mtx);
}
static void
fasttrap_disable_callbacks(void)
{
ASSERT(MUTEX_HELD(&cpu_lock));
HERE();
dmutex_enter(&fasttrap_count_mtx);
ASSERT(fasttrap_pid_count > 0);
fasttrap_pid_count--;
if (fasttrap_pid_count == 0) {