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Diffstat (limited to 'lib/libdtrace/common/dt_proc.c')
| -rw-r--r-- | lib/libdtrace/common/dt_proc.c | 1223 |
1 files changed, 1223 insertions, 0 deletions
diff --git a/lib/libdtrace/common/dt_proc.c b/lib/libdtrace/common/dt_proc.c new file mode 100644 index 000000000000..b8662bf67f34 --- /dev/null +++ b/lib/libdtrace/common/dt_proc.c @@ -0,0 +1,1223 @@ +/* + * 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 2007 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#pragma ident "%Z%%M% %I% %E% SMI" + +/* + * DTrace Process Control + * + * This file provides a set of routines that permit libdtrace and its clients + * to create and grab process handles using libproc, and to share these handles + * between library mechanisms that need libproc access, such as ustack(), and + * client mechanisms that need libproc access, such as dtrace(1M) -c and -p. + * The library provides several mechanisms in the libproc control layer: + * + * Reference Counting: The library code and client code can independently grab + * the same process handles without interfering with one another. Only when + * the reference count drops to zero and the handle is not being cached (see + * below for more information on caching) will Prelease() be called on it. + * + * Handle Caching: If a handle is grabbed PGRAB_RDONLY (e.g. by ustack()) and + * the reference count drops to zero, the handle is not immediately released. + * Instead, libproc handles are maintained on dph_lrulist in order from most- + * recently accessed to least-recently accessed. Idle handles are maintained + * until a pre-defined LRU cache limit is exceeded, permitting repeated calls + * to ustack() to avoid the overhead of releasing and re-grabbing processes. + * + * Process Control: For processes that are grabbed for control (~PGRAB_RDONLY) + * or created by dt_proc_create(), a control thread is created to provide + * callbacks on process exit and symbol table caching on dlopen()s. + * + * MT-Safety: Libproc is not MT-Safe, so dt_proc_lock() and dt_proc_unlock() + * are provided to synchronize access to the libproc handle between libdtrace + * code and client code and the control thread's use of the ps_prochandle. + * + * NOTE: MT-Safety is NOT provided for libdtrace itself, or for use of the + * dtrace_proc_grab/dtrace_proc_create mechanisms. Like all exported libdtrace + * calls, these are assumed to be MT-Unsafe. MT-Safety is ONLY provided for + * synchronization between libdtrace control threads and the client thread. + * + * The ps_prochandles themselves are maintained along with a dt_proc_t struct + * in a hash table indexed by PID. This provides basic locking and reference + * counting. The dt_proc_t is also maintained in LRU order on dph_lrulist. + * The dph_lrucnt and dph_lrulim count the number of cacheable processes and + * the current limit on the number of actively cached entries. + * + * The control thread for a process establishes breakpoints at the rtld_db + * locations of interest, updates mappings and symbol tables at these points, + * and handles exec and fork (by always following the parent). The control + * thread automatically exits when the process dies or control is lost. + * + * A simple notification mechanism is provided for libdtrace clients using + * dtrace_handle_proc() for notification of PS_UNDEAD or PS_LOST events. If + * such an event occurs, the dt_proc_t itself is enqueued on a notification + * list and the control thread broadcasts to dph_cv. dtrace_sleep() will wake + * up using this condition and will then call the client handler as necessary. + */ + +#include <sys/wait.h> +#if defined(sun) +#include <sys/lwp.h> +#endif +#include <strings.h> +#include <signal.h> +#include <assert.h> +#include <errno.h> + +#include <dt_proc.h> +#include <dt_pid.h> +#include <dt_impl.h> + +#define IS_SYS_EXEC(w) (w == SYS_exec || w == SYS_execve) +#define IS_SYS_FORK(w) (w == SYS_vfork || w == SYS_fork1 || \ + w == SYS_forkall || w == SYS_forksys) + +#ifdef DOODAD +static dt_bkpt_t * +dt_proc_bpcreate(dt_proc_t *dpr, uintptr_t addr, dt_bkpt_f *func, void *data) +{ + struct ps_prochandle *P = dpr->dpr_proc; + dt_bkpt_t *dbp; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + if ((dbp = dt_zalloc(dpr->dpr_hdl, sizeof (dt_bkpt_t))) != NULL) { + dbp->dbp_func = func; + dbp->dbp_data = data; + dbp->dbp_addr = addr; + + if (Psetbkpt(P, dbp->dbp_addr, &dbp->dbp_instr) == 0) + dbp->dbp_active = B_TRUE; + + dt_list_append(&dpr->dpr_bps, dbp); + } + + return (dbp); +} +#endif + +static void +dt_proc_bpdestroy(dt_proc_t *dpr, int delbkpts) +{ +#if defined(sun) + int state = Pstate(dpr->dpr_proc); +#else + int state = proc_state(dpr->dpr_proc); +#endif + dt_bkpt_t *dbp, *nbp; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + for (dbp = dt_list_next(&dpr->dpr_bps); dbp != NULL; dbp = nbp) { +printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); +#ifdef DOODAD + if (delbkpts && dbp->dbp_active && + state != PS_LOST && state != PS_UNDEAD) { + (void) Pdelbkpt(dpr->dpr_proc, + dbp->dbp_addr, dbp->dbp_instr); + } +#endif + nbp = dt_list_next(dbp); + dt_list_delete(&dpr->dpr_bps, dbp); + dt_free(dpr->dpr_hdl, dbp); + } +} + +#ifdef DOODAD +static void +dt_proc_bpmatch(dtrace_hdl_t *dtp, dt_proc_t *dpr) +{ + const lwpstatus_t *psp = &Pstatus(dpr->dpr_proc)->pr_lwp; + dt_bkpt_t *dbp; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + for (dbp = dt_list_next(&dpr->dpr_bps); + dbp != NULL; dbp = dt_list_next(dbp)) { + if (psp->pr_reg[R_PC] == dbp->dbp_addr) + break; + } + + if (dbp == NULL) { + dt_dprintf("pid %d: spurious breakpoint wakeup for %lx\n", + (int)dpr->dpr_pid, (ulong_t)psp->pr_reg[R_PC]); + return; + } + + dt_dprintf("pid %d: hit breakpoint at %lx (%lu)\n", + (int)dpr->dpr_pid, (ulong_t)dbp->dbp_addr, ++dbp->dbp_hits); + + dbp->dbp_func(dtp, dpr, dbp->dbp_data); + (void) Pxecbkpt(dpr->dpr_proc, dbp->dbp_instr); +} +#endif + +static void +dt_proc_bpenable(dt_proc_t *dpr) +{ + dt_bkpt_t *dbp; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + for (dbp = dt_list_next(&dpr->dpr_bps); + dbp != NULL; dbp = dt_list_next(dbp)) { +printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); +#ifdef DOODAD + if (!dbp->dbp_active && Psetbkpt(dpr->dpr_proc, + dbp->dbp_addr, &dbp->dbp_instr) == 0) + dbp->dbp_active = B_TRUE; +#endif + } + + dt_dprintf("breakpoints enabled\n"); +} + +static void +dt_proc_bpdisable(dt_proc_t *dpr) +{ + dt_bkpt_t *dbp; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + for (dbp = dt_list_next(&dpr->dpr_bps); + dbp != NULL; dbp = dt_list_next(dbp)) { +printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); +#ifdef DOODAD + if (dbp->dbp_active && Pdelbkpt(dpr->dpr_proc, + dbp->dbp_addr, dbp->dbp_instr) == 0) + dbp->dbp_active = B_FALSE; +#endif + } + + dt_dprintf("breakpoints disabled\n"); +} + +static void +dt_proc_notify(dtrace_hdl_t *dtp, dt_proc_hash_t *dph, dt_proc_t *dpr, + const char *msg) +{ + dt_proc_notify_t *dprn = dt_alloc(dtp, sizeof (dt_proc_notify_t)); + + if (dprn == NULL) { + dt_dprintf("failed to allocate notification for %d %s\n", + (int)dpr->dpr_pid, msg); + } else { + dprn->dprn_dpr = dpr; + if (msg == NULL) + dprn->dprn_errmsg[0] = '\0'; + else + (void) strlcpy(dprn->dprn_errmsg, msg, + sizeof (dprn->dprn_errmsg)); + + (void) pthread_mutex_lock(&dph->dph_lock); + + dprn->dprn_next = dph->dph_notify; + dph->dph_notify = dprn; + + (void) pthread_cond_broadcast(&dph->dph_cv); + (void) pthread_mutex_unlock(&dph->dph_lock); + } +} + +/* + * Check to see if the control thread was requested to stop when the victim + * process reached a particular event (why) rather than continuing the victim. + * If 'why' is set in the stop mask, we wait on dpr_cv for dt_proc_continue(). + * If 'why' is not set, this function returns immediately and does nothing. + */ +static void +dt_proc_stop(dt_proc_t *dpr, uint8_t why) +{ + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + assert(why != DT_PROC_STOP_IDLE); + + if (dpr->dpr_stop & why) { + dpr->dpr_stop |= DT_PROC_STOP_IDLE; + dpr->dpr_stop &= ~why; + + (void) pthread_cond_broadcast(&dpr->dpr_cv); + + /* + * We disable breakpoints while stopped to preserve the + * integrity of the program text for both our own disassembly + * and that of the kernel. + */ + dt_proc_bpdisable(dpr); + + while (dpr->dpr_stop & DT_PROC_STOP_IDLE) + (void) pthread_cond_wait(&dpr->dpr_cv, &dpr->dpr_lock); + + dt_proc_bpenable(dpr); + } +} + +/*ARGSUSED*/ +static void +dt_proc_bpmain(dtrace_hdl_t *dtp, dt_proc_t *dpr, const char *fname) +{ + dt_dprintf("pid %d: breakpoint at %s()\n", (int)dpr->dpr_pid, fname); + dt_proc_stop(dpr, DT_PROC_STOP_MAIN); +} + +#if defined(sun) +static void +dt_proc_rdevent(dtrace_hdl_t *dtp, dt_proc_t *dpr, const char *evname) +{ + rd_event_msg_t rdm; + rd_err_e err; + + if ((err = rd_event_getmsg(dpr->dpr_rtld, &rdm)) != RD_OK) { + dt_dprintf("pid %d: failed to get %s event message: %s\n", + (int)dpr->dpr_pid, evname, rd_errstr(err)); + return; + } + + dt_dprintf("pid %d: rtld event %s type=%d state %d\n", + (int)dpr->dpr_pid, evname, rdm.type, rdm.u.state); + + switch (rdm.type) { + case RD_DLACTIVITY: + if (rdm.u.state != RD_CONSISTENT) + break; + + Pupdate_syms(dpr->dpr_proc); + if (dt_pid_create_probes_module(dtp, dpr) != 0) + dt_proc_notify(dtp, dtp->dt_procs, dpr, + dpr->dpr_errmsg); + + break; + case RD_PREINIT: + Pupdate_syms(dpr->dpr_proc); + dt_proc_stop(dpr, DT_PROC_STOP_PREINIT); + break; + case RD_POSTINIT: + Pupdate_syms(dpr->dpr_proc); + dt_proc_stop(dpr, DT_PROC_STOP_POSTINIT); + break; + } +} + +static void +dt_proc_rdwatch(dt_proc_t *dpr, rd_event_e event, const char *evname) +{ + rd_notify_t rdn; + rd_err_e err; + + if ((err = rd_event_addr(dpr->dpr_rtld, event, &rdn)) != RD_OK) { + dt_dprintf("pid %d: failed to get event address for %s: %s\n", + (int)dpr->dpr_pid, evname, rd_errstr(err)); + return; + } + + if (rdn.type != RD_NOTIFY_BPT) { + dt_dprintf("pid %d: event %s has unexpected type %d\n", + (int)dpr->dpr_pid, evname, rdn.type); + return; + } + + (void) dt_proc_bpcreate(dpr, rdn.u.bptaddr, + (dt_bkpt_f *)dt_proc_rdevent, (void *)evname); +} + +/* + * Common code for enabling events associated with the run-time linker after + * attaching to a process or after a victim process completes an exec(2). + */ +static void +dt_proc_attach(dt_proc_t *dpr, int exec) +{ + const pstatus_t *psp = Pstatus(dpr->dpr_proc); + rd_err_e err; + GElf_Sym sym; + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + + if (exec) { + if (psp->pr_lwp.pr_errno != 0) + return; /* exec failed: nothing needs to be done */ + + dt_proc_bpdestroy(dpr, B_FALSE); + Preset_maps(dpr->dpr_proc); + } + + if ((dpr->dpr_rtld = Prd_agent(dpr->dpr_proc)) != NULL && + (err = rd_event_enable(dpr->dpr_rtld, B_TRUE)) == RD_OK) { + dt_proc_rdwatch(dpr, RD_PREINIT, "RD_PREINIT"); + dt_proc_rdwatch(dpr, RD_POSTINIT, "RD_POSTINIT"); + dt_proc_rdwatch(dpr, RD_DLACTIVITY, "RD_DLACTIVITY"); + } else { + dt_dprintf("pid %d: failed to enable rtld events: %s\n", + (int)dpr->dpr_pid, dpr->dpr_rtld ? rd_errstr(err) : + "rtld_db agent initialization failed"); + } + + Pupdate_maps(dpr->dpr_proc); + + if (Pxlookup_by_name(dpr->dpr_proc, LM_ID_BASE, + "a.out", "main", &sym, NULL) == 0) { + (void) dt_proc_bpcreate(dpr, (uintptr_t)sym.st_value, + (dt_bkpt_f *)dt_proc_bpmain, "a.out`main"); + } else { + dt_dprintf("pid %d: failed to find a.out`main: %s\n", + (int)dpr->dpr_pid, strerror(errno)); + } +} + +/* + * Wait for a stopped process to be set running again by some other debugger. + * This is typically not required by /proc-based debuggers, since the usual + * model is that one debugger controls one victim. But DTrace, as usual, has + * its own needs: the stop() action assumes that prun(1) or some other tool + * will be applied to resume the victim process. This could be solved by + * adding a PCWRUN directive to /proc, but that seems like overkill unless + * other debuggers end up needing this functionality, so we implement a cheap + * equivalent to PCWRUN using the set of existing kernel mechanisms. + * + * Our intent is really not just to wait for the victim to run, but rather to + * wait for it to run and then stop again for a reason other than the current + * PR_REQUESTED stop. Since PCWSTOP/Pstopstatus() can be applied repeatedly + * to a stopped process and will return the same result without affecting the + * victim, we can just perform these operations repeatedly until Pstate() + * changes, the representative LWP ID changes, or the stop timestamp advances. + * dt_proc_control() will then rediscover the new state and continue as usual. + * When the process is still stopped in the same exact state, we sleep for a + * brief interval before waiting again so as not to spin consuming CPU cycles. + */ +static void +dt_proc_waitrun(dt_proc_t *dpr) +{ + struct ps_prochandle *P = dpr->dpr_proc; + const lwpstatus_t *psp = &Pstatus(P)->pr_lwp; + + int krflag = psp->pr_flags & (PR_KLC | PR_RLC); + timestruc_t tstamp = psp->pr_tstamp; + lwpid_t lwpid = psp->pr_lwpid; + + const long wstop = PCWSTOP; + int pfd = Pctlfd(P); + + assert(DT_MUTEX_HELD(&dpr->dpr_lock)); + assert(psp->pr_flags & PR_STOPPED); + assert(Pstate(P) == PS_STOP); + + /* + * While we are waiting for the victim to run, clear PR_KLC and PR_RLC + * so that if the libdtrace client is killed, the victim stays stopped. + * dt_proc_destroy() will also observe this and perform PRELEASE_HANG. + */ + (void) Punsetflags(P, krflag); + Psync(P); + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + + while (!dpr->dpr_quit) { + if (write(pfd, &wstop, sizeof (wstop)) == -1 && errno == EINTR) + continue; /* check dpr_quit and continue waiting */ + + (void) pthread_mutex_lock(&dpr->dpr_lock); + (void) Pstopstatus(P, PCNULL, 0); + psp = &Pstatus(P)->pr_lwp; + + /* + * If we've reached a new state, found a new representative, or + * the stop timestamp has changed, restore PR_KLC/PR_RLC to its + * original setting and then return with dpr_lock held. + */ + if (Pstate(P) != PS_STOP || psp->pr_lwpid != lwpid || + bcmp(&psp->pr_tstamp, &tstamp, sizeof (tstamp)) != 0) { + (void) Psetflags(P, krflag); + Psync(P); + return; + } + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + (void) poll(NULL, 0, MILLISEC / 2); + } + + (void) pthread_mutex_lock(&dpr->dpr_lock); +} +#endif + +typedef struct dt_proc_control_data { + dtrace_hdl_t *dpcd_hdl; /* DTrace handle */ + dt_proc_t *dpcd_proc; /* proccess to control */ +} dt_proc_control_data_t; + +/* + * Main loop for all victim process control threads. We initialize all the + * appropriate /proc control mechanisms, and then enter a loop waiting for + * the process to stop on an event or die. We process any events by calling + * appropriate subroutines, and exit when the victim dies or we lose control. + * + * The control thread synchronizes the use of dpr_proc with other libdtrace + * threads using dpr_lock. We hold the lock for all of our operations except + * waiting while the process is running: this is accomplished by writing a + * PCWSTOP directive directly to the underlying /proc/<pid>/ctl file. If the + * libdtrace client wishes to exit or abort our wait, SIGCANCEL can be used. + */ +static void * +dt_proc_control(void *arg) +{ + dt_proc_control_data_t *datap = arg; + dtrace_hdl_t *dtp = datap->dpcd_hdl; + dt_proc_t *dpr = datap->dpcd_proc; + dt_proc_hash_t *dph = dpr->dpr_hdl->dt_procs; + struct ps_prochandle *P = dpr->dpr_proc; + int pid = dpr->dpr_pid; + +#if defined(sun) + int pfd = Pctlfd(P); + + const long wstop = PCWSTOP; +#endif + int notify = B_FALSE; + + /* + * We disable the POSIX thread cancellation mechanism so that the + * client program using libdtrace can't accidentally cancel our thread. + * dt_proc_destroy() uses SIGCANCEL explicitly to simply poke us out + * of PCWSTOP with EINTR, at which point we will see dpr_quit and exit. + */ + (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL); + + /* + * Set up the corresponding process for tracing by libdtrace. We want + * to be able to catch breakpoints and efficiently single-step over + * them, and we need to enable librtld_db to watch libdl activity. + */ + (void) pthread_mutex_lock(&dpr->dpr_lock); + +#if defined(sun) + (void) Punsetflags(P, PR_ASYNC); /* require synchronous mode */ + (void) Psetflags(P, PR_BPTADJ); /* always adjust eip on x86 */ + (void) Punsetflags(P, PR_FORK); /* do not inherit on fork */ + + (void) Pfault(P, FLTBPT, B_TRUE); /* always trace breakpoints */ + (void) Pfault(P, FLTTRACE, B_TRUE); /* always trace single-step */ + + /* + * We must trace exit from exec() system calls so that if the exec is + * successful, we can reset our breakpoints and re-initialize libproc. + */ + (void) Psysexit(P, SYS_exec, B_TRUE); + (void) Psysexit(P, SYS_execve, B_TRUE); + + /* + * We must trace entry and exit for fork() system calls in order to + * disable our breakpoints temporarily during the fork. We do not set + * the PR_FORK flag, so if fork succeeds the child begins executing and + * does not inherit any other tracing behaviors or a control thread. + */ + (void) Psysentry(P, SYS_vfork, B_TRUE); + (void) Psysexit(P, SYS_vfork, B_TRUE); + (void) Psysentry(P, SYS_fork1, B_TRUE); + (void) Psysexit(P, SYS_fork1, B_TRUE); + (void) Psysentry(P, SYS_forkall, B_TRUE); + (void) Psysexit(P, SYS_forkall, B_TRUE); + (void) Psysentry(P, SYS_forksys, B_TRUE); + (void) Psysexit(P, SYS_forksys, B_TRUE); + + Psync(P); /* enable all /proc changes */ + dt_proc_attach(dpr, B_FALSE); /* enable rtld breakpoints */ + + /* + * If PR_KLC is set, we created the process; otherwise we grabbed it. + * Check for an appropriate stop request and wait for dt_proc_continue. + */ + if (Pstatus(P)->pr_flags & PR_KLC) + dt_proc_stop(dpr, DT_PROC_STOP_CREATE); + else + dt_proc_stop(dpr, DT_PROC_STOP_GRAB); + + if (Psetrun(P, 0, 0) == -1) { + dt_dprintf("pid %d: failed to set running: %s\n", + (int)dpr->dpr_pid, strerror(errno)); + } +#else + /* + * If PR_KLC is set, we created the process; otherwise we grabbed it. + * Check for an appropriate stop request and wait for dt_proc_continue. + */ + if (proc_getflags(P) & PR_KLC) + dt_proc_stop(dpr, DT_PROC_STOP_CREATE); + else + dt_proc_stop(dpr, DT_PROC_STOP_GRAB); + + if (proc_continue(P) != 0) + dt_dprintf("pid %d: failed to set running: %s\n", + (int)dpr->dpr_pid, strerror(errno)); +#endif + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + + /* + * Wait for the process corresponding to this control thread to stop, + * process the event, and then set it running again. We want to sleep + * with dpr_lock *unheld* so that other parts of libdtrace can use the + * ps_prochandle in the meantime (e.g. ustack()). To do this, we write + * a PCWSTOP directive directly to the underlying /proc/<pid>/ctl file. + * Once the process stops, we wake up, grab dpr_lock, and then call + * Pwait() (which will return immediately) and do our processing. + */ + while (!dpr->dpr_quit) { +#if defined(sun) + const lwpstatus_t *psp; + + if (write(pfd, &wstop, sizeof (wstop)) == -1 && errno == EINTR) + continue; /* check dpr_quit and continue waiting */ +#else + /* Wait for the process to report status. */ + proc_wait(P); +#endif + + (void) pthread_mutex_lock(&dpr->dpr_lock); + +#if defined(sun) +pwait_locked: + if (Pstopstatus(P, PCNULL, 0) == -1 && errno == EINTR) { + (void) pthread_mutex_unlock(&dpr->dpr_lock); + continue; /* check dpr_quit and continue waiting */ + } +#endif + +#if defined(sun) + switch (Pstate(P)) { +#else + switch (proc_state(P)) { +#endif + case PS_STOP: +#ifdef DOODAD + psp = &Pstatus(P)->pr_lwp; + + dt_dprintf("pid %d: proc stopped showing %d/%d\n", + pid, psp->pr_why, psp->pr_what); + + /* + * If the process stops showing PR_REQUESTED, then the + * DTrace stop() action was applied to it or another + * debugging utility (e.g. pstop(1)) asked it to stop. + * In either case, the user's intention is for the + * process to remain stopped until another external + * mechanism (e.g. prun(1)) is applied. So instead of + * setting the process running ourself, we wait for + * someone else to do so. Once that happens, we return + * to our normal loop waiting for an event of interest. + */ + if (psp->pr_why == PR_REQUESTED) { + dt_proc_waitrun(dpr); + (void) pthread_mutex_unlock(&dpr->dpr_lock); + continue; + } + + /* + * If the process stops showing one of the events that + * we are tracing, perform the appropriate response. + * Note that we ignore PR_SUSPENDED, PR_CHECKPOINT, and + * PR_JOBCONTROL by design: if one of these conditions + * occurs, we will fall through to Psetrun() but the + * process will remain stopped in the kernel by the + * corresponding mechanism (e.g. job control stop). + */ + if (psp->pr_why == PR_FAULTED && psp->pr_what == FLTBPT) + dt_proc_bpmatch(dtp, dpr); + else if (psp->pr_why == PR_SYSENTRY && + IS_SYS_FORK(psp->pr_what)) + dt_proc_bpdisable(dpr); + else if (psp->pr_why == PR_SYSEXIT && + IS_SYS_FORK(psp->pr_what)) + dt_proc_bpenable(dpr); + else if (psp->pr_why == PR_SYSEXIT && + IS_SYS_EXEC(psp->pr_what)) + dt_proc_attach(dpr, B_TRUE); +#endif + break; + + case PS_LOST: +#if defined(sun) + if (Preopen(P) == 0) + goto pwait_locked; +#endif + + dt_dprintf("pid %d: proc lost: %s\n", + pid, strerror(errno)); + + dpr->dpr_quit = B_TRUE; + notify = B_TRUE; + break; + + case PS_UNDEAD: + dt_dprintf("pid %d: proc died\n", pid); + dpr->dpr_quit = B_TRUE; + notify = B_TRUE; + break; + } + +#if defined(sun) + if (Pstate(P) != PS_UNDEAD && Psetrun(P, 0, 0) == -1) { + dt_dprintf("pid %d: failed to set running: %s\n", + (int)dpr->dpr_pid, strerror(errno)); + } +#endif + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + } + + /* + * If the control thread detected PS_UNDEAD or PS_LOST, then enqueue + * the dt_proc_t structure on the dt_proc_hash_t notification list. + */ + if (notify) + dt_proc_notify(dtp, dph, dpr, NULL); + + /* + * Destroy and remove any remaining breakpoints, set dpr_done and clear + * dpr_tid to indicate the control thread has exited, and notify any + * waiting thread in dt_proc_destroy() that we have succesfully exited. + */ + (void) pthread_mutex_lock(&dpr->dpr_lock); + + dt_proc_bpdestroy(dpr, B_TRUE); + dpr->dpr_done = B_TRUE; + dpr->dpr_tid = 0; + + (void) pthread_cond_broadcast(&dpr->dpr_cv); + (void) pthread_mutex_unlock(&dpr->dpr_lock); + + return (NULL); +} + +/*PRINTFLIKE3*/ +static struct ps_prochandle * +dt_proc_error(dtrace_hdl_t *dtp, dt_proc_t *dpr, const char *format, ...) +{ + va_list ap; + + va_start(ap, format); + dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap); + va_end(ap); + + if (dpr->dpr_proc != NULL) +#if defined(sun) + Prelease(dpr->dpr_proc, 0); +#else + proc_detach(dpr->dpr_proc); +#endif + + dt_free(dtp, dpr); + (void) dt_set_errno(dtp, EDT_COMPILER); + return (NULL); +} + +dt_proc_t * +dt_proc_lookup(dtrace_hdl_t *dtp, struct ps_prochandle *P, int remove) +{ + dt_proc_hash_t *dph = dtp->dt_procs; +#if defined(sun) + pid_t pid = Pstatus(P)->pr_pid; +#else + pid_t pid = proc_getpid(P); +#endif + dt_proc_t *dpr, **dpp = &dph->dph_hash[pid & (dph->dph_hashlen - 1)]; + + for (dpr = *dpp; dpr != NULL; dpr = dpr->dpr_hash) { + if (dpr->dpr_pid == pid) + break; + else + dpp = &dpr->dpr_hash; + } + + assert(dpr != NULL); + assert(dpr->dpr_proc == P); + + if (remove) + *dpp = dpr->dpr_hash; /* remove from pid hash chain */ + + return (dpr); +} + +static void +dt_proc_destroy(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE); + dt_proc_hash_t *dph = dtp->dt_procs; + dt_proc_notify_t *npr, **npp; + int rflag; + + assert(dpr != NULL); + + /* + * If neither PR_KLC nor PR_RLC is set, then the process is stopped by + * an external debugger and we were waiting in dt_proc_waitrun(). + * Leave the process in this condition using PRELEASE_HANG. + */ +#if defined(sun) + if (!(Pstatus(dpr->dpr_proc)->pr_flags & (PR_KLC | PR_RLC))) { +#else + if (!(proc_getflags(dpr->dpr_proc) & (PR_KLC | PR_RLC))) { +#endif + dt_dprintf("abandoning pid %d\n", (int)dpr->dpr_pid); +#if defined(sun) + rflag = PRELEASE_HANG; +#else + rflag = 0 /* XXX */; +#endif + } else { + dt_dprintf("releasing pid %d\n", (int)dpr->dpr_pid); + rflag = 0; /* apply kill or run-on-last-close */ + } + + if (dpr->dpr_tid) { + /* + * Set the dpr_quit flag to tell the daemon thread to exit. We + * send it a SIGCANCEL to poke it out of PCWSTOP or any other + * long-term /proc system call. Our daemon threads have POSIX + * cancellation disabled, so EINTR will be the only effect. We + * then wait for dpr_done to indicate the thread has exited. + * + * We can't use pthread_kill() to send SIGCANCEL because the + * interface forbids it and we can't use pthread_cancel() + * because with cancellation disabled it won't actually + * send SIGCANCEL to the target thread, so we use _lwp_kill() + * to do the job. This is all built on evil knowledge of + * the details of the cancellation mechanism in libc. + */ + (void) pthread_mutex_lock(&dpr->dpr_lock); + dpr->dpr_quit = B_TRUE; +#if defined(sun) + (void) _lwp_kill(dpr->dpr_tid, SIGCANCEL); +#else + (void) pthread_kill(dpr->dpr_tid, SIGUSR1); +#endif + + /* + * If the process is currently idling in dt_proc_stop(), re- + * enable breakpoints and poke it into running again. + */ + if (dpr->dpr_stop & DT_PROC_STOP_IDLE) { + dt_proc_bpenable(dpr); + dpr->dpr_stop &= ~DT_PROC_STOP_IDLE; + (void) pthread_cond_broadcast(&dpr->dpr_cv); + } + + while (!dpr->dpr_done) + (void) pthread_cond_wait(&dpr->dpr_cv, &dpr->dpr_lock); + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + } + + /* + * Before we free the process structure, remove this dt_proc_t from the + * lookup hash, and then walk the dt_proc_hash_t's notification list + * and remove this dt_proc_t if it is enqueued. + */ + (void) pthread_mutex_lock(&dph->dph_lock); + (void) dt_proc_lookup(dtp, P, B_TRUE); + npp = &dph->dph_notify; + + while ((npr = *npp) != NULL) { + if (npr->dprn_dpr == dpr) { + *npp = npr->dprn_next; + dt_free(dtp, npr); + } else { + npp = &npr->dprn_next; + } + } + + (void) pthread_mutex_unlock(&dph->dph_lock); + + /* + * Remove the dt_proc_list from the LRU list, release the underlying + * libproc handle, and free our dt_proc_t data structure. + */ + if (dpr->dpr_cacheable) { + assert(dph->dph_lrucnt != 0); + dph->dph_lrucnt--; + } + + dt_list_delete(&dph->dph_lrulist, dpr); +#if defined(sun) + Prelease(dpr->dpr_proc, rflag); +#else + proc_detach(dpr->dpr_proc); +#endif + dt_free(dtp, dpr); +} + +static int +dt_proc_create_thread(dtrace_hdl_t *dtp, dt_proc_t *dpr, uint_t stop) +{ + dt_proc_control_data_t data; + sigset_t nset, oset; + pthread_attr_t a; + int err; + + (void) pthread_mutex_lock(&dpr->dpr_lock); + dpr->dpr_stop |= stop; /* set bit for initial rendezvous */ + + (void) pthread_attr_init(&a); + (void) pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED); + + (void) sigfillset(&nset); + (void) sigdelset(&nset, SIGABRT); /* unblocked for assert() */ +#if defined(sun) + (void) sigdelset(&nset, SIGCANCEL); /* see dt_proc_destroy() */ +#else + (void) sigdelset(&nset, SIGUSR1); /* see dt_proc_destroy() */ +#endif + + data.dpcd_hdl = dtp; + data.dpcd_proc = dpr; + + (void) pthread_sigmask(SIG_SETMASK, &nset, &oset); + err = pthread_create(&dpr->dpr_tid, &a, dt_proc_control, &data); + (void) pthread_sigmask(SIG_SETMASK, &oset, NULL); + + /* + * If the control thread was created, then wait on dpr_cv for either + * dpr_done to be set (the victim died or the control thread failed) + * or DT_PROC_STOP_IDLE to be set, indicating that the victim is now + * stopped by /proc and the control thread is at the rendezvous event. + * On success, we return with the process and control thread stopped: + * the caller can then apply dt_proc_continue() to resume both. + */ + if (err == 0) { + while (!dpr->dpr_done && !(dpr->dpr_stop & DT_PROC_STOP_IDLE)) + (void) pthread_cond_wait(&dpr->dpr_cv, &dpr->dpr_lock); + + /* + * If dpr_done is set, the control thread aborted before it + * reached the rendezvous event. This is either due to PS_LOST + * or PS_UNDEAD (i.e. the process died). We try to provide a + * small amount of useful information to help figure it out. + */ + if (dpr->dpr_done) { +#if defined(sun) + const psinfo_t *prp = Ppsinfo(dpr->dpr_proc); + int stat = prp ? prp->pr_wstat : 0; +#endif + int pid = dpr->dpr_pid; + +#if defined(sun) + if (Pstate(dpr->dpr_proc) == PS_LOST) { +#else + if (proc_state(dpr->dpr_proc) == PS_LOST) { +#endif + (void) dt_proc_error(dpr->dpr_hdl, dpr, + "failed to control pid %d: process exec'd " + "set-id or unobservable program\n", pid); +#if defined(sun) + } else if (WIFSIGNALED(stat)) { + (void) dt_proc_error(dpr->dpr_hdl, dpr, + "failed to control pid %d: process died " + "from signal %d\n", pid, WTERMSIG(stat)); + } else { + (void) dt_proc_error(dpr->dpr_hdl, dpr, + "failed to control pid %d: process exited " + "with status %d\n", pid, WEXITSTATUS(stat)); +#endif + } + + err = ESRCH; /* cause grab() or create() to fail */ + } + } else { + (void) dt_proc_error(dpr->dpr_hdl, dpr, + "failed to create control thread for process-id %d: %s\n", + (int)dpr->dpr_pid, strerror(err)); + } + + (void) pthread_mutex_unlock(&dpr->dpr_lock); + (void) pthread_attr_destroy(&a); + + return (err); +} + +struct ps_prochandle * +dt_proc_create(dtrace_hdl_t *dtp, const char *file, char *const *argv) +{ + dt_proc_hash_t *dph = dtp->dt_procs; + dt_proc_t *dpr; + int err; + + if ((dpr = dt_zalloc(dtp, sizeof (dt_proc_t))) == NULL) + return (NULL); /* errno is set for us */ + + (void) pthread_mutex_init(&dpr->dpr_lock, NULL); + (void) pthread_cond_init(&dpr->dpr_cv, NULL); + +#if defined(sun) + if ((dpr->dpr_proc = Pcreate(file, argv, &err, NULL, 0)) == NULL) { + return (dt_proc_error(dtp, dpr, + "failed to execute %s: %s\n", file, Pcreate_error(err))); + } + + dpr->dpr_hdl = dtp; + dpr->dpr_pid = Pstatus(dpr->dpr_proc)->pr_pid; + + (void) Punsetflags(dpr->dpr_proc, PR_RLC); + (void) Psetflags(dpr->dpr_proc, PR_KLC); +#else + (void) proc_clearflags(dpr->dpr_proc, PR_RLC); + (void) proc_setflags(dpr->dpr_proc, PR_KLC); + if ((err = proc_create(file, argv, &dpr->dpr_proc)) != 0) + return (dt_proc_error(dtp, dpr, + "failed to execute %s: %s\n", file, strerror(err))); + dpr->dpr_hdl = dtp; + dpr->dpr_pid = proc_getpid(dpr->dpr_proc); +#endif + +#if defined(sun) + if (dt_proc_create_thread(dtp, dpr, dtp->dt_prcmode) != 0) +#else + if (dt_proc_create_thread(dtp, dpr, DT_PROC_STOP_IDLE) != 0) +#endif + return (NULL); /* dt_proc_error() has been called for us */ + + dpr->dpr_hash = dph->dph_hash[dpr->dpr_pid & (dph->dph_hashlen - 1)]; + dph->dph_hash[dpr->dpr_pid & (dph->dph_hashlen - 1)] = dpr; + dt_list_prepend(&dph->dph_lrulist, dpr); + + dt_dprintf("created pid %d\n", (int)dpr->dpr_pid); + dpr->dpr_refs++; + + return (dpr->dpr_proc); +} + +struct ps_prochandle * +dt_proc_grab(dtrace_hdl_t *dtp, pid_t pid, int flags, int nomonitor) +{ + dt_proc_hash_t *dph = dtp->dt_procs; + uint_t h = pid & (dph->dph_hashlen - 1); + dt_proc_t *dpr, *opr; + int err; + + /* + * Search the hash table for the pid. If it is already grabbed or + * created, move the handle to the front of the lrulist, increment + * the reference count, and return the existing ps_prochandle. + */ + for (dpr = dph->dph_hash[h]; dpr != NULL; dpr = dpr->dpr_hash) { + if (dpr->dpr_pid == pid && !dpr->dpr_stale) { + /* + * If the cached handle was opened read-only and + * this request is for a writeable handle, mark + * the cached handle as stale and open a new handle. + * Since it's stale, unmark it as cacheable. + */ + if (dpr->dpr_rdonly && !(flags & PGRAB_RDONLY)) { + dt_dprintf("upgrading pid %d\n", (int)pid); + dpr->dpr_stale = B_TRUE; + dpr->dpr_cacheable = B_FALSE; + dph->dph_lrucnt--; + break; + } + + dt_dprintf("grabbed pid %d (cached)\n", (int)pid); + dt_list_delete(&dph->dph_lrulist, dpr); + dt_list_prepend(&dph->dph_lrulist, dpr); + dpr->dpr_refs++; + return (dpr->dpr_proc); + } + } + + if ((dpr = dt_zalloc(dtp, sizeof (dt_proc_t))) == NULL) + return (NULL); /* errno is set for us */ + + (void) pthread_mutex_init(&dpr->dpr_lock, NULL); + (void) pthread_cond_init(&dpr->dpr_cv, NULL); + +#if defined(sun) + if ((dpr->dpr_proc = Pgrab(pid, flags, &err)) == NULL) { + return (dt_proc_error(dtp, dpr, + "failed to grab pid %d: %s\n", (int)pid, Pgrab_error(err))); + } +#else + if ((err = proc_attach(pid, flags, &dpr->dpr_proc)) != 0) + return (dt_proc_error(dtp, dpr, + "failed to grab pid %d: %s\n", (int) pid, strerror(err))); +#endif + + dpr->dpr_hdl = dtp; + dpr->dpr_pid = pid; + +#if defined(sun) + (void) Punsetflags(dpr->dpr_proc, PR_KLC); + (void) Psetflags(dpr->dpr_proc, PR_RLC); +#else + (void) proc_clearflags(dpr->dpr_proc, PR_KLC); + (void) proc_setflags(dpr->dpr_proc, PR_RLC); +#endif + + /* + * If we are attempting to grab the process without a monitor + * thread, then mark the process cacheable only if it's being + * grabbed read-only. If we're currently caching more process + * handles than dph_lrulim permits, attempt to find the + * least-recently-used handle that is currently unreferenced and + * release it from the cache. Otherwise we are grabbing the process + * for control: create a control thread for this process and store + * its ID in dpr->dpr_tid. + */ + if (nomonitor || (flags & PGRAB_RDONLY)) { + if (dph->dph_lrucnt >= dph->dph_lrulim) { + for (opr = dt_list_prev(&dph->dph_lrulist); + opr != NULL; opr = dt_list_prev(opr)) { + if (opr->dpr_cacheable && opr->dpr_refs == 0) { + dt_proc_destroy(dtp, opr->dpr_proc); + break; + } + } + } + + if (flags & PGRAB_RDONLY) { + dpr->dpr_cacheable = B_TRUE; + dpr->dpr_rdonly = B_TRUE; + dph->dph_lrucnt++; + } + + } else if (dt_proc_create_thread(dtp, dpr, DT_PROC_STOP_GRAB) != 0) + return (NULL); /* dt_proc_error() has been called for us */ + + dpr->dpr_hash = dph->dph_hash[h]; + dph->dph_hash[h] = dpr; + dt_list_prepend(&dph->dph_lrulist, dpr); + + dt_dprintf("grabbed pid %d\n", (int)pid); + dpr->dpr_refs++; + + return (dpr->dpr_proc); +} + +void +dt_proc_release(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE); + dt_proc_hash_t *dph = dtp->dt_procs; + + assert(dpr != NULL); + assert(dpr->dpr_refs != 0); + + if (--dpr->dpr_refs == 0 && + (!dpr->dpr_cacheable || dph->dph_lrucnt > dph->dph_lrulim)) + dt_proc_destroy(dtp, P); +} + +void +dt_proc_continue(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE); + + (void) pthread_mutex_lock(&dpr->dpr_lock); + + if (dpr->dpr_stop & DT_PROC_STOP_IDLE) { + dpr->dpr_stop &= ~DT_PROC_STOP_IDLE; + (void) pthread_cond_broadcast(&dpr->dpr_cv); + } + + (void) pthread_mutex_unlock(&dpr->dpr_lock); +} + +void +dt_proc_lock(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE); + int err = pthread_mutex_lock(&dpr->dpr_lock); + assert(err == 0); /* check for recursion */ +} + +void +dt_proc_unlock(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE); + int err = pthread_mutex_unlock(&dpr->dpr_lock); + assert(err == 0); /* check for unheld lock */ +} + +void +dt_proc_hash_create(dtrace_hdl_t *dtp) +{ + if ((dtp->dt_procs = dt_zalloc(dtp, sizeof (dt_proc_hash_t) + + sizeof (dt_proc_t *) * _dtrace_pidbuckets - 1)) != NULL) { + + (void) pthread_mutex_init(&dtp->dt_procs->dph_lock, NULL); + (void) pthread_cond_init(&dtp->dt_procs->dph_cv, NULL); + + dtp->dt_procs->dph_hashlen = _dtrace_pidbuckets; + dtp->dt_procs->dph_lrulim = _dtrace_pidlrulim; + } +} + +void +dt_proc_hash_destroy(dtrace_hdl_t *dtp) +{ + dt_proc_hash_t *dph = dtp->dt_procs; + dt_proc_t *dpr; + + while ((dpr = dt_list_next(&dph->dph_lrulist)) != NULL) + dt_proc_destroy(dtp, dpr->dpr_proc); + + dtp->dt_procs = NULL; + dt_free(dtp, dph); +} + +struct ps_prochandle * +dtrace_proc_create(dtrace_hdl_t *dtp, const char *file, char *const *argv) +{ + dt_ident_t *idp = dt_idhash_lookup(dtp->dt_macros, "target"); + struct ps_prochandle *P = dt_proc_create(dtp, file, argv); + + if (P != NULL && idp != NULL && idp->di_id == 0) +#if defined(sun) + idp->di_id = Pstatus(P)->pr_pid; /* $target = created pid */ +#else + idp->di_id = proc_getpid(P); /* $target = created pid */ +#endif + + return (P); +} + +struct ps_prochandle * +dtrace_proc_grab(dtrace_hdl_t *dtp, pid_t pid, int flags) +{ + dt_ident_t *idp = dt_idhash_lookup(dtp->dt_macros, "target"); + struct ps_prochandle *P = dt_proc_grab(dtp, pid, flags, 0); + + if (P != NULL && idp != NULL && idp->di_id == 0) + idp->di_id = pid; /* $target = grabbed pid */ + + return (P); +} + +void +dtrace_proc_release(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_release(dtp, P); +} + +void +dtrace_proc_continue(dtrace_hdl_t *dtp, struct ps_prochandle *P) +{ + dt_proc_continue(dtp, P); +} |