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      1 /*
      2   This file is part of drd, a thread error detector.
      3 
      4   Copyright (C) 2006-2012 Bart Van Assche <bvanassche (at) acm.org>.
      5 
      6   This program is free software; you can redistribute it and/or
      7   modify it under the terms of the GNU General Public License as
      8   published by the Free Software Foundation; either version 2 of the
      9   License, or (at your option) any later version.
     10 
     11   This program is distributed in the hope that it will be useful, but
     12   WITHOUT ANY WARRANTY; without even the implied warranty of
     13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14   General Public License for more details.
     15 
     16   You should have received a copy of the GNU General Public License
     17   along with this program; if not, write to the Free Software
     18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     19   02111-1307, USA.
     20 
     21   The GNU General Public License is contained in the file COPYING.
     22 */
     23 
     24 
     25 #include "drd_clientobj.h"
     26 #include "drd_error.h"
     27 #include "drd_semaphore.h"
     28 #include "drd_suppression.h"
     29 #include "pub_tool_errormgr.h"    // VG_(maybe_record_error)()
     30 #include "pub_tool_libcassert.h"  // tl_assert()
     31 #include "pub_tool_libcprint.h"   // VG_(printf)()
     32 #include "pub_tool_machine.h"     // VG_(get_IP)()
     33 #include "pub_tool_mallocfree.h"  // VG_(malloc), VG_(free)
     34 #include "pub_tool_threadstate.h" // VG_(get_running_tid)()
     35 
     36 
     37 /* Local functions. */
     38 
     39 static void semaphore_cleanup(struct semaphore_info* p);
     40 
     41 
     42 /* Local variables. */
     43 
     44 static Bool s_trace_semaphore;
     45 static ULong s_semaphore_segment_creation_count;
     46 
     47 
     48 /* Function definitions. */
     49 
     50 /** Push a segment at the end of the queue 'p->last_sem_post_seg'. */
     51 static void drd_segment_push(struct semaphore_info* p, Segment* sg)
     52 {
     53    Word n;
     54 
     55    tl_assert(sg);
     56    n = VG_(addToXA)(p->last_sem_post_seg, &sg);
     57 #if 0
     58    VG_(message)(Vg_DebugMsg, "0x%lx push: added at position %ld/%ld",
     59                 p->a1, n, VG_(sizeXA)(p->last_sem_post_seg));
     60 #endif
     61    tl_assert(*(Segment**)VG_(indexXA)(p->last_sem_post_seg, n) == sg);
     62 }
     63 
     64 /** Pop a segment from the beginning of the queue 'p->last_sem_post_seg'. */
     65 static Segment* drd_segment_pop(struct semaphore_info* p)
     66 {
     67    Word sz;
     68    Segment* sg;
     69 
     70    sz = VG_(sizeXA)(p->last_sem_post_seg);
     71 #if 0
     72    VG_(message)(Vg_DebugMsg, "0x%lx pop:  removed from position %ld/%ld",
     73                 p->a1, sz - 1, sz);
     74 #endif
     75    sg = 0;
     76    if (sz > 0)
     77    {
     78       sg = *(Segment**)VG_(indexXA)(p->last_sem_post_seg, sz - 1);
     79       tl_assert(sg);
     80       VG_(dropTailXA)(p->last_sem_post_seg, 1);
     81    }
     82    return sg;
     83 }
     84 
     85 /** Enable or disable tracing of semaphore actions. */
     86 void DRD_(semaphore_set_trace)(const Bool trace_semaphore)
     87 {
     88    s_trace_semaphore = trace_semaphore;
     89 }
     90 
     91 /**
     92  * Initialize the memory 'p' points at as a semaphore_info structure for the
     93  * client semaphore at client addres 'semaphore'.
     94  */
     95 static
     96 void drd_semaphore_initialize(struct semaphore_info* const p,
     97                               const Addr semaphore)
     98 {
     99    tl_assert(semaphore != 0);
    100    tl_assert(p->a1 == semaphore);
    101    tl_assert(p->type == ClientSemaphore);
    102 
    103    p->cleanup           = (void(*)(DrdClientobj*))semaphore_cleanup;
    104    p->delete_thread     = 0;
    105    p->waits_to_skip     = 0;
    106    p->value             = 0;
    107    p->waiters           = 0;
    108    p->last_sem_post_tid = DRD_INVALID_THREADID;
    109    p->last_sem_post_seg = VG_(newXA)(VG_(malloc), "drd.sg-stack",
    110                                      VG_(free), sizeof(Segment*));
    111 }
    112 
    113 /**
    114  * Free the memory that was allocated by semaphore_initialize(). Called by
    115  * DRD_(clientobj_remove)().
    116  */
    117 static void semaphore_cleanup(struct semaphore_info* p)
    118 {
    119    Segment* sg;
    120 
    121    if (p->waiters > 0)
    122    {
    123       SemaphoreErrInfo sei = { DRD_(thread_get_running_tid)(), p->a1 };
    124       VG_(maybe_record_error)(VG_(get_running_tid)(),
    125                               SemaphoreErr,
    126                               VG_(get_IP)(VG_(get_running_tid)()),
    127                               "Destruction of semaphore that is being waited"
    128                               " upon",
    129                               &sei);
    130    }
    131    while ((sg = drd_segment_pop(p)))
    132       DRD_(sg_put)(sg);
    133    VG_(deleteXA)(p->last_sem_post_seg);
    134 }
    135 
    136 /**
    137  * Return a pointer to the structure with information about the specified
    138  * client semaphore. Allocate a new structure if such a structure did not
    139  * yet exist.
    140  */
    141 static
    142 struct semaphore_info*
    143 drd_semaphore_get_or_allocate(const Addr semaphore)
    144 {
    145    struct semaphore_info *p;
    146 
    147    tl_assert(offsetof(DrdClientobj, semaphore) == 0);
    148    p = &(DRD_(clientobj_get)(semaphore, ClientSemaphore)->semaphore);
    149    if (p == 0)
    150    {
    151       tl_assert(offsetof(DrdClientobj, semaphore) == 0);
    152       p = &(DRD_(clientobj_add)(semaphore, ClientSemaphore)->semaphore);
    153       drd_semaphore_initialize(p, semaphore);
    154    }
    155    return p;
    156 }
    157 
    158 /**
    159  * Return a pointer to the structure with information about the specified
    160  * client semaphore, or null if no such structure was found.
    161  */
    162 static struct semaphore_info* semaphore_get(const Addr semaphore)
    163 {
    164    tl_assert(offsetof(DrdClientobj, semaphore) == 0);
    165    return &(DRD_(clientobj_get)(semaphore, ClientSemaphore)->semaphore);
    166 }
    167 
    168 /** Called before sem_init(). */
    169 struct semaphore_info* DRD_(semaphore_init)(const Addr semaphore,
    170                                             const Word pshared,
    171                                             const UInt value)
    172 {
    173    struct semaphore_info* p;
    174    Segment* sg;
    175 
    176    if (s_trace_semaphore)
    177       DRD_(trace_msg)("[%d] sem_init      0x%lx value %u",
    178                       DRD_(thread_get_running_tid)(), semaphore, value);
    179 
    180    p = semaphore_get(semaphore);
    181    if (p)
    182    {
    183       const ThreadId vg_tid = VG_(get_running_tid)();
    184       SemaphoreErrInfo SEI = { DRD_(thread_get_running_tid)(), semaphore };
    185       VG_(maybe_record_error)(vg_tid,
    186                               SemaphoreErr,
    187                               VG_(get_IP)(vg_tid),
    188                               "Semaphore reinitialization",
    189                               &SEI);
    190       // Remove all segments from the segment stack.
    191       while ((sg = drd_segment_pop(p)))
    192       {
    193          DRD_(sg_put)(sg);
    194       }
    195    }
    196    else
    197    {
    198 #if defined(VGO_darwin)
    199       const ThreadId vg_tid = VG_(get_running_tid)();
    200       GenericErrInfo GEI = { DRD_(thread_get_running_tid)(), 0 };
    201       VG_(maybe_record_error)(vg_tid,
    202 			      GenericErr,
    203 			      VG_(get_IP)(vg_tid),
    204 			      "sem_init() is not yet supported on Darwin",
    205 			      &GEI);
    206       return NULL;
    207 #else
    208       p = drd_semaphore_get_or_allocate(semaphore);
    209 #endif
    210    }
    211    tl_assert(p);
    212    p->waits_to_skip = value;
    213    p->value         = value;
    214    return p;
    215 }
    216 
    217 /** Called after sem_destroy(). */
    218 void DRD_(semaphore_destroy)(const Addr semaphore)
    219 {
    220    struct semaphore_info* p;
    221 
    222    p = semaphore_get(semaphore);
    223 
    224    if (s_trace_semaphore)
    225       DRD_(trace_msg)("[%d] sem_destroy   0x%lx value %u",
    226                       DRD_(thread_get_running_tid)(), semaphore,
    227                       p ? p->value : 0);
    228 
    229    if (p == 0)
    230    {
    231       GenericErrInfo GEI = {
    232 	 .tid  = DRD_(thread_get_running_tid)(),
    233 	 .addr = semaphore,
    234       };
    235       VG_(maybe_record_error)(VG_(get_running_tid)(),
    236                               GenericErr,
    237                               VG_(get_IP)(VG_(get_running_tid)()),
    238                               "Not a semaphore",
    239                               &GEI);
    240       return;
    241    }
    242 
    243    DRD_(clientobj_remove)(semaphore, ClientSemaphore);
    244 }
    245 
    246 /** Called after sem_open(). */
    247 struct semaphore_info* DRD_(semaphore_open)(const Addr semaphore,
    248                                             const Char* name, const Word oflag,
    249                                             const Word mode, const UInt value)
    250 {
    251    struct semaphore_info* p;
    252    Segment* sg;
    253 
    254    if (s_trace_semaphore)
    255       DRD_(trace_msg)("[%d] sem_open      0x%lx name %s"
    256                       " oflag %#lx mode %#lo value %u",
    257                       DRD_(thread_get_running_tid)(),
    258                       semaphore, name, oflag, mode, value);
    259 
    260    /* Return if the sem_open() call failed. */
    261    if (! semaphore)
    262       return NULL;
    263 
    264    p = semaphore_get(semaphore);
    265    if (p)
    266    {
    267       const ThreadId vg_tid = VG_(get_running_tid)();
    268       SemaphoreErrInfo SEI = { DRD_(thread_get_running_tid)(), semaphore };
    269       VG_(maybe_record_error)(vg_tid,
    270                               SemaphoreErr,
    271                               VG_(get_IP)(vg_tid),
    272                               "Semaphore reinitialization",
    273                               &SEI);
    274       // Remove all segments from the segment stack.
    275       while ((sg = drd_segment_pop(p)))
    276       {
    277          DRD_(sg_put)(sg);
    278       }
    279    }
    280    else
    281    {
    282       p = drd_semaphore_get_or_allocate(semaphore);
    283    }
    284    tl_assert(p);
    285    p->waits_to_skip = value;
    286    p->value         = value;
    287    return p;
    288 }
    289 
    290 /** Called before sem_close(). */
    291 void DRD_(semaphore_close)(const Addr semaphore)
    292 {
    293    struct semaphore_info* p;
    294 
    295    p = semaphore_get(semaphore);
    296 
    297    if (s_trace_semaphore)
    298       DRD_(trace_msg)("[%d] sem_close     0x%lx value %u",
    299                       DRD_(thread_get_running_tid)(), semaphore,
    300                       p ? p->value : 0);
    301 
    302    if (p == 0)
    303    {
    304       GenericErrInfo GEI = {
    305 	 .tid  = DRD_(thread_get_running_tid)(),
    306 	 .addr = semaphore,
    307       };
    308       VG_(maybe_record_error)(VG_(get_running_tid)(),
    309                               GenericErr,
    310                               VG_(get_IP)(VG_(get_running_tid)()),
    311                               "Not a semaphore",
    312                               &GEI);
    313       return;
    314    }
    315 
    316    DRD_(clientobj_remove)(semaphore, ClientSemaphore);
    317 }
    318 
    319 /** Called before sem_wait(). */
    320 void DRD_(semaphore_pre_wait)(const Addr semaphore)
    321 {
    322    struct semaphore_info* p;
    323 
    324    tl_assert(semaphore < semaphore + 1);
    325    p = drd_semaphore_get_or_allocate(semaphore);
    326    tl_assert(p);
    327    p->waiters++;
    328 
    329    if ((Word)(p->waiters) <= 0)
    330    {
    331       SemaphoreErrInfo sei = { DRD_(thread_get_running_tid)(), semaphore };
    332       VG_(maybe_record_error)(VG_(get_running_tid)(),
    333                               SemaphoreErr,
    334                               VG_(get_IP)(VG_(get_running_tid)()),
    335                               "Invalid semaphore",
    336                               &sei);
    337    }
    338 }
    339 
    340 /**
    341  * Called after sem_wait() finished.
    342  * @note Some C libraries do not set the 'waited' value correctly.
    343  */
    344 void DRD_(semaphore_post_wait)(const DrdThreadId tid, const Addr semaphore,
    345                                const Bool waited)
    346 {
    347    struct semaphore_info* p;
    348    Segment* sg;
    349 
    350    tl_assert(waited == 0 || waited == 1);
    351    p = semaphore_get(semaphore);
    352    if (s_trace_semaphore)
    353       DRD_(trace_msg)("[%d] sem_wait      0x%lx value %u -> %u%s",
    354                       DRD_(thread_get_running_tid)(), semaphore,
    355                       p ? p->value : 0, p ? p->value - waited : 0,
    356 		      waited ? "" : " (did not wait)");
    357 
    358    if (p) {
    359       p->waiters--;
    360       p->value -= waited;
    361    }
    362 
    363    /*
    364     * Note: if another thread destroyed and reinitialized a semaphore while
    365     * the current thread was waiting in sem_wait, p->waiters may have been
    366     * set to zero by drd_semaphore_initialize() after
    367     * DRD_(semaphore_pre_wait)() has finished before
    368     * DRD_(semaphore_post_wait)() has been called.
    369     */
    370    if (p == NULL || (Int)(p->value) < 0 || (Word)(p->waiters) < 0)
    371    {
    372       SemaphoreErrInfo sei = { DRD_(thread_get_running_tid)(), semaphore };
    373       VG_(maybe_record_error)(VG_(get_running_tid)(),
    374                               SemaphoreErr,
    375                               VG_(get_IP)(VG_(get_running_tid)()),
    376                               "Invalid semaphore",
    377                               &sei);
    378       return;
    379    }
    380 
    381    if (!waited)
    382       return;
    383 
    384    if (p->waits_to_skip > 0)
    385       p->waits_to_skip--;
    386    else
    387    {
    388       sg = drd_segment_pop(p);
    389       tl_assert(sg);
    390       if (p->last_sem_post_tid != tid
    391           && p->last_sem_post_tid != DRD_INVALID_THREADID)
    392       {
    393          DRD_(thread_new_segment_and_combine_vc)(tid, sg);
    394       }
    395       else
    396          DRD_(thread_new_segment)(tid);
    397       s_semaphore_segment_creation_count++;
    398       DRD_(sg_put)(sg);
    399    }
    400 }
    401 
    402 /** Called before sem_post(). */
    403 void DRD_(semaphore_pre_post)(const DrdThreadId tid, const Addr semaphore)
    404 {
    405    struct semaphore_info* p;
    406    Segment* sg;
    407 
    408    p = drd_semaphore_get_or_allocate(semaphore);
    409    p->value++;
    410 
    411    if (s_trace_semaphore)
    412       DRD_(trace_msg)("[%d] sem_post      0x%lx value %u -> %u",
    413                       DRD_(thread_get_running_tid)(),
    414                       semaphore, p->value - 1, p->value);
    415 
    416    p->last_sem_post_tid = tid;
    417    sg = 0;
    418    DRD_(thread_get_latest_segment)(&sg, tid);
    419    tl_assert(sg);
    420    drd_segment_push(p, sg);
    421    DRD_(thread_new_segment)(tid);
    422    s_semaphore_segment_creation_count++;
    423 }
    424 
    425 /** Called after sem_post() finished. */
    426 void DRD_(semaphore_post_post)(const DrdThreadId tid, const Addr semaphore,
    427                                const Bool succeeded)
    428 {
    429    /*
    430     * Note: it is hard to implement the sem_post() wrapper correctly in
    431     * case sem_post() returns an error code. This is because handling this
    432     * case correctly requires restoring the vector clock associated with
    433     * the semaphore to its original value here. In order to do that without
    434     * introducing a race condition, extra locking has to be added around
    435     * each semaphore call. Such extra locking would have to be added in
    436     * drd_pthread_intercepts.c. However, it is hard to implement
    437     * synchronization in drd_pthread_intercepts.c in a portable way without
    438     * calling already redirected functions.
    439     */
    440 }
    441 
    442 ULong DRD_(get_semaphore_segment_creation_count)(void)
    443 {
    444    return s_semaphore_segment_creation_count;
    445 }
    446