/* $NetBSD: refclock_shm.c,v 1.1.1.2.16.1 2014/12/25 02:13:07 snj Exp $ */ /* * refclock_shm - clock driver for utc via shared memory * - under construction - * To add new modes: Extend or union the shmTime-struct. Do not * extend/shrink size, because otherwise existing implementations * will specify wrong size of shared memory-segment * PB 18.3.97 */ #ifdef HAVE_CONFIG_H # include #endif #include "ntp_types.h" #if defined(REFCLOCK) && defined(CLOCK_SHM) #include "ntpd.h" #undef fileno #include "ntp_io.h" #undef fileno #include "ntp_refclock.h" #undef fileno #include "timespecops.h" #undef fileno #include "ntp_stdlib.h" #undef fileno #include #undef fileno #ifndef SYS_WINNT # include # include # include # include # include #endif /* * This driver supports a reference clock attached thru shared memory */ /* * SHM interface definitions */ #define PRECISION (-1) /* precision assumed (0.5 s) */ #define REFID "SHM" /* reference ID */ #define DESCRIPTION "SHM/Shared memory interface" #define NSAMPLES 3 /* stages of median filter */ /* * Function prototypes */ static int shm_start (int unit, struct peer *peer); static void shm_shutdown (int unit, struct peer *peer); static void shm_poll (int unit, struct peer *peer); static void shm_timer (int unit, struct peer *peer); static void shm_peek (int unit, struct peer *peer); static void shm_clockstats (int unit, struct peer *peer); static void shm_control (int unit, const struct refclockstat * in_st, struct refclockstat * out_st, struct peer *peer); /* * Transfer vector */ struct refclock refclock_shm = { shm_start, /* start up driver */ shm_shutdown, /* shut down driver */ shm_poll, /* transmit poll message */ shm_control, /* control settings */ noentry, /* not used: init */ noentry, /* not used: buginfo */ shm_timer, /* once per second */ }; struct shmTime { int mode; /* 0 - if valid is set: * use values, * clear valid * 1 - if valid is set: * if count before and after read of values is equal, * use values * clear valid */ volatile int count; time_t clockTimeStampSec; int clockTimeStampUSec; time_t receiveTimeStampSec; int receiveTimeStampUSec; int leap; int precision; int nsamples; volatile int valid; unsigned clockTimeStampNSec; /* Unsigned ns timestamps */ unsigned receiveTimeStampNSec; /* Unsigned ns timestamps */ int dummy[8]; }; struct shmunit { struct shmTime *shm; /* pointer to shared memory segment */ /* debugging/monitoring counters - reset when printed */ int ticks; /* number of attempts to read data*/ int good; /* number of valid samples */ int notready; /* number of peeks without data ready */ int bad; /* number of invalid samples */ int clash; /* number of access clashes while reading */ time_t max_delta; /* difference limit */ time_t max_delay; /* age/stale limit */ }; struct shmTime *getShmTime(int); struct shmTime *getShmTime (int unit) { #ifndef SYS_WINNT int shmid=0; /* 0x4e545030 is NTP0. * Big units will give non-ascii but that's OK * as long as everybody does it the same way. */ shmid=shmget (0x4e545030 + unit, sizeof (struct shmTime), IPC_CREAT | ((unit < 2) ? 0600 : 0666)); if (shmid == -1) { /* error */ msyslog(LOG_ERR, "SHM shmget (unit %d): %m", unit); return 0; } else { /* no error */ struct shmTime *p = (struct shmTime *)shmat (shmid, 0, 0); if (p == (struct shmTime *)-1) { /* error */ msyslog(LOG_ERR, "SHM shmat (unit %d): %m", unit); return 0; } return p; } #else char buf[10]; LPSECURITY_ATTRIBUTES psec = 0; HANDLE shmid = 0; SECURITY_DESCRIPTOR sd; SECURITY_ATTRIBUTES sa; snprintf(buf, sizeof(buf), "NTP%d", unit); if (unit >= 2) { /* world access */ if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) { msyslog(LOG_ERR,"SHM InitializeSecurityDescriptor (unit %d): %m", unit); return 0; } if (!SetSecurityDescriptorDacl(&sd, 1, 0, 0)) { msyslog(LOG_ERR, "SHM SetSecurityDescriptorDacl (unit %d): %m", unit); return 0; } sa.nLength=sizeof (SECURITY_ATTRIBUTES); sa.lpSecurityDescriptor = &sd; sa.bInheritHandle = 0; psec = &sa; } shmid = CreateFileMapping ((HANDLE)0xffffffff, psec, PAGE_READWRITE, 0, sizeof (struct shmTime), buf); if (!shmid) { /*error*/ char buf[1000]; FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM, 0, GetLastError (), 0, buf, sizeof (buf), 0); msyslog(LOG_ERR, "SHM CreateFileMapping (unit %d): %s", unit, buf); return 0; } else { struct shmTime *p = (struct shmTime *) MapViewOfFile (shmid, FILE_MAP_WRITE, 0, 0, sizeof (struct shmTime)); if (p == 0) { /*error*/ char buf[1000]; FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM, 0, GetLastError (), 0, buf, sizeof (buf), 0); msyslog(LOG_ERR,"SHM MapViewOfFile (unit %d): %s", unit, buf) return 0; } return p; } #endif } /* * shm_start - attach to shared memory */ static int shm_start( int unit, struct peer *peer ) { struct refclockproc *pp; struct shmunit *up; pp = peer->procptr; pp->io.clock_recv = noentry; pp->io.srcclock = peer; pp->io.datalen = 0; pp->io.fd = -1; up = emalloc_zero(sizeof(*up)); up->shm = getShmTime(unit); /* * Initialize miscellaneous peer variables */ memcpy((char *)&pp->refid, REFID, 4); if (up->shm != 0) { pp->unitptr = up; up->shm->precision = PRECISION; peer->precision = up->shm->precision; up->shm->valid = 0; up->shm->nsamples = NSAMPLES; pp->clockdesc = DESCRIPTION; /* items to be changed later in 'shm_control()': */ up->max_delay = 5; up->max_delta = 4*3600; return 1; } else { free(up); pp->unitptr = NULL; return 0; } } /* * shm_control - configure flag1/time2 params * * These are not yet available during 'shm_start', so we have to do any * pre-computations we want to avoid during regular poll/timer callbacks * in this callback. */ static void shm_control( int unit, const struct refclockstat * in_st, struct refclockstat * out_st, struct peer * peer ) { struct refclockproc *pp; struct shmunit *up; pp = peer->procptr; up = pp->unitptr; if (NULL == up) return; if (pp->sloppyclockflag & CLK_FLAG1) up->max_delta = 0; else if (pp->fudgetime2 < 1. || pp->fudgetime2 > 86400.) up->max_delta = 4*3600; else up->max_delta = (time_t)floor(pp->fudgetime2 + 0.5); } /* * shm_shutdown - shut down the clock */ static void shm_shutdown( int unit, struct peer *peer ) { struct refclockproc *pp; struct shmunit *up; pp = peer->procptr; up = pp->unitptr; if (NULL == up) return; #ifndef SYS_WINNT /* HMS: shmdt() wants char* or const void * */ (void) shmdt ((char *)up->shm); #else UnmapViewOfFile (up->shm); #endif free(up); } /* * shm_timer - called every second */ static void shm_timer(int unit, struct peer *peer) { shm_peek(unit, peer); } /* * shm_poll - called by the transmit procedure */ static void shm_poll( int unit, struct peer *peer ) { struct refclockproc *pp; struct shmunit *up; int major_error; pp = peer->procptr; up = pp->unitptr; pp->polls++; /* get dominant reason if we have no samples at all */ major_error = max(up->notready, up->bad); major_error = max(major_error, up->clash); /* * Process median filter samples. If none received, see what * happened, tell the core and keep going. */ if (pp->coderecv != pp->codeproc) { /* have some samples, everything OK */ pp->lastref = pp->lastrec; refclock_receive(peer); } else if (NULL == up->shm) { /* is this possible at all? */ /* we're out of business without SHM access */ refclock_report(peer, CEVNT_FAULT); } else if (major_error == up->clash) { /* too many collisions is like a bad signal */ refclock_report(peer, CEVNT_PROP); } else if (major_error == up->bad) { /* too much stale/bad/garbled data */ refclock_report(peer, CEVNT_BADREPLY); } else { /* in any other case assume it's just a timeout */ refclock_report(peer, CEVNT_TIMEOUT); } /* shm_clockstats() clears the tallies, so it must be last... */ shm_clockstats(unit, peer); } /* * shm_peek - try to grab a sample */ static void shm_peek( int unit, struct peer *peer ) { struct refclockproc *pp; struct shmunit *up; /* access order is important for lock-free SHM access; we ** enforce order by treating the whole structure volatile. ** ** IMPORTANT NOTE: This does not protect from reordering on CPU ** level, and it does nothing for cache consistency and ** visibility of changes by other cores. We need atomic and/or ** fence instructions for that. */ volatile struct shmTime *shm; struct timespec tvr; struct timespec tvt; l_fp tsrcv; l_fp tsref; unsigned int c; unsigned int cns_new, rns_new; int cnt; /* for formatting 'a_lastcode': */ struct calendar cd; time_t tt, now; vint64 ts; /* * This is the main routine. It snatches the time from the shm * board and tacks on a local timestamp. */ pp = peer->procptr; up = pp->unitptr; up->ticks++; if (up->shm == 0) { /* try to map again - this may succeed if meanwhile some- body has ipcrm'ed the old (unaccessible) shared mem segment */ up->shm = getShmTime(unit); } shm = up->shm; if (shm == 0) { DPRINTF(1, ("%s: no SHM segment\n", refnumtoa(&peer->srcadr))); return; } if ( ! shm->valid) { DPRINTF(1, ("%s: SHM not ready\n", refnumtoa(&peer->srcadr))); up->notready++; return; } switch (shm->mode) { case 0: tvr.tv_sec = shm->receiveTimeStampSec; tvr.tv_nsec = shm->receiveTimeStampUSec * 1000; rns_new = shm->receiveTimeStampNSec; tvt.tv_sec = shm->clockTimeStampSec; tvt.tv_nsec = shm->clockTimeStampUSec * 1000; cns_new = shm->clockTimeStampNSec; /* Since the following comparisons are between unsigned ** variables they are always well defined, and any ** (signed) underflow will turn into very large unsigned ** values, well above the 1000 cutoff. ** ** Note: The usecs *must* be a *truncated* ** representation of the nsecs. This code will fail for ** *rounded* usecs, and the logic to deal with ** wrap-arounds in the presence of rounded values is ** much more convoluted. */ if ( ((cns_new - (unsigned)tvt.tv_nsec) < 1000) && ((rns_new - (unsigned)tvr.tv_nsec) < 1000)) { tvt.tv_nsec = cns_new; tvr.tv_nsec = rns_new; } /* At this point tvr and tvt contains valid ns-level ** timestamps, possibly generated by extending the old ** us-level timestamps */ DPRINTF(2, ("%s: SHM type 0 sample\n", refnumtoa(&peer->srcadr))); break; case 1: cnt = shm->count; tvr.tv_sec = shm->receiveTimeStampSec; tvr.tv_nsec = shm->receiveTimeStampUSec * 1000; rns_new = shm->receiveTimeStampNSec; tvt.tv_sec = shm->clockTimeStampSec; tvt.tv_nsec = shm->clockTimeStampUSec * 1000; cns_new = shm->clockTimeStampNSec; if (cnt != shm->count) { DPRINTF(1, ("%s: type 1 access clash\n", refnumtoa(&peer->srcadr))); msyslog (LOG_NOTICE, "SHM: access clash in shared memory"); up->clash++; return; } /* See the case above for an explanation of the ** following test. */ if ( ((cns_new - (unsigned)tvt.tv_nsec) < 1000) && ((rns_new - (unsigned)tvr.tv_nsec) < 1000)) { tvt.tv_nsec = cns_new; tvr.tv_nsec = rns_new; } /* At this point tvr and tvt contains valid ns-level ** timestamps, possibly generated by extending the old ** us-level timestamps */ DPRINTF(2, ("%s: SHM type 1 sample\n", refnumtoa(&peer->srcadr))); break; default: DPRINTF(1, ("%s: SHM type blooper, mode=%d\n", refnumtoa(&peer->srcadr), shm->mode)); up->bad++; msyslog (LOG_ERR, "SHM: bad mode found in shared memory: %d", shm->mode); return; } shm->valid = 0; /* format the last time code in human-readable form into * 'pp->a_lastcode'. Someone claimed: "NetBSD has incompatible * tv_sec". I can't find a base for this claim, but we can work * around that potential problem. BTW, simply casting a pointer * is a receipe for disaster on some architectures. */ tt = (time_t)tvt.tv_sec; ts = time_to_vint64(&tt); ntpcal_time_to_date(&cd, &ts); /* add ntpq -c cv timecode in ISO 8601 format */ c = snprintf(pp->a_lastcode, sizeof(pp->a_lastcode), "%04u-%02u-%02uT%02u:%02u:%02u.%09ldZ", cd.year, cd.month, cd.monthday, cd.hour, cd.minute, cd.second, (long)tvt.tv_nsec); pp->lencode = (c < sizeof(pp->a_lastcode)) ? c : 0; /* check 1: age control of local time stamp */ time(&now); tt = now - tvr.tv_sec; if (tt < 0 || tt > up->max_delay) { DPRINTF(1, ("%s:SHM stale/bad receive time, delay=%llds\n", refnumtoa(&peer->srcadr), (long long)tt)); up->bad++; msyslog (LOG_ERR, "SHM: stale/bad receive time, delay=%llds", (long long)tt); return; } /* check 2: delta check */ tt = tvr.tv_sec - tvt.tv_sec - (tvr.tv_nsec < tvt.tv_nsec); if (tt < 0) tt = -tt; if (up->max_delta > 0 && tt > up->max_delta) { DPRINTF(1, ("%s: SHM diff limit exceeded, delta=%llds\n", refnumtoa(&peer->srcadr), (long long)tt)); up->bad++; msyslog (LOG_ERR, "SHM: difference limit exceeded, delta=%llds\n", (long long)tt); return; } /* if we really made it to this point... we're winners! */ DPRINTF(2, ("%s: SHM feeding data\n", refnumtoa(&peer->srcadr))); tsrcv = tspec_stamp_to_lfp(tvr); tsref = tspec_stamp_to_lfp(tvt); pp->leap = shm->leap; peer->precision = shm->precision; refclock_process_offset(pp, tsref, tsrcv, pp->fudgetime1); up->good++; } /* * shm_clockstats - dump and reset counters */ static void shm_clockstats( int unit, struct peer *peer ) { struct refclockproc *pp; struct shmunit *up; char logbuf[64]; unsigned int llen; pp = peer->procptr; up = pp->unitptr; if (pp->sloppyclockflag & CLK_FLAG4) { /* if snprintf() returns a negative values on errors ** (some older ones do) make sure we are NUL ** terminated. Using an unsigned result does the trick. */ llen = snprintf(logbuf, sizeof(logbuf), "%3d %3d %3d %3d %3d", up->ticks, up->good, up->notready, up->bad, up->clash); logbuf[min(llen, sizeof(logbuf)-1)] = '\0'; record_clock_stats(&peer->srcadr, logbuf); } up->ticks = up->good = up->notready = up->bad = up->clash = 0; } #else NONEMPTY_TRANSLATION_UNIT #endif /* REFCLOCK */