src/runtime/thread.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <sched.h>
   4 #include <signal.h>
   5 #include <stddef.h>
   6 #include <errno.h>
   7 #ifndef CLONE_PARENT            /* lameass glibc 2.2  doesn't define this */
   8 #define CLONE_PARENT 0x00008000 /* even though the manpage documents it */
   9 #endif
  10 #include "runtime.h"
  11 #include "sbcl.h"
  12 #include "validate.h"           /* for CONTROL_STACK_SIZE etc */
  13 #include "thread.h"
  14 #include "arch.h"
  15 #include "target-arch-os.h"
  16 #include "os.h"
  17 #include "globals.h"
  18 #include "dynbind.h"
  19 #include "genesis/cons.h"
  20 #define ALIEN_STACK_SIZE (1*1024*1024) /* 1Mb size chosen at random */
  21
  22 int dynamic_values_bytes=4096*sizeof(lispobj);  /* same for all threads */
  23 struct thread *all_threads;
  24 volatile lispobj all_threads_lock;
  25 volatile int countdown_to_gc;
  26 extern struct interrupt_data * global_interrupt_data;
  27
  28 void get_spinlock(lispobj *word,int value);
  29
  30 /* this is the first thing that clone() runs in the child (which is
  31  * why the silly calling convention).  Basically it calls the user's
  32  * requested lisp function after doing arch_os_thread_init and
  33  * whatever other bookkeeping needs to be done
  34  */
  35
  36 /* set go to 0 to stop the thread before it starts.  Convenient if you
  37 * want to attach a debugger to it before it does anything */
  38 volatile int go=1;
  39
  40 int
  41 new_thread_trampoline(struct thread *th)
  42 {
  43     lispobj function;
  44     lispobj *args = NULL;
  45     function = th->unbound_marker;
  46     if(go==0) {
  47         fprintf(stderr, "/pausing 0x%lx(%d,%d) before new_thread_trampoline(0x%lx)\n",
  48                 (unsigned long)th,th->pid,getpid(),(unsigned long)function);
  49         while(go==0) ;
  50         fprintf(stderr, "/continue\n");
  51     }
  52     th->unbound_marker = UNBOUND_MARKER_WIDETAG;
  53 #ifdef LISP_FEATURE_SB_THREAD
  54     /* wait here until our thread is linked into all_threads: see below */
  55     while(th->pid<1) sched_yield();
  56 #else
  57     if(th->pid < 1)
  58         lose("th->pid not set up right");
  59 #endif
  60
  61     if(arch_os_thread_init(th)==0)
  62         return 1;               /* failure.  no, really */
  63 #if !defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_X86)
  64     return call_into_lisp_first_time(function,args,0);
  65 #else
  66     return funcall0(function);
  67 #endif
  68 }
  69
  70 /* this is called from any other thread to create the new one, and
  71  * initialize all parts of it that can be initialized from another
  72  * thread
  73  */
  74
  75 pid_t create_thread(lispobj initial_function) {
  76     union per_thread_data *per_thread;
  77     struct thread *th=0;        /*  subdue gcc */
  78     void *spaces=0;
  79     pid_t kid_pid;
  80
  81     /* may as well allocate all the spaces at once: it saves us from
  82      * having to decide what to do if only some of the allocations
  83      * succeed */
  84     spaces=os_validate(0,
  85                        THREAD_CONTROL_STACK_SIZE+
  86                        BINDING_STACK_SIZE+
  87                        ALIEN_STACK_SIZE+
  88                        dynamic_values_bytes+
  89                        32*SIGSTKSZ
  90                        );
  91     if(!spaces) goto cleanup;
  92     per_thread=(union per_thread_data *)
  93         (spaces+
  94          THREAD_CONTROL_STACK_SIZE+
  95          BINDING_STACK_SIZE+
  96          ALIEN_STACK_SIZE);
  97
  98     th=&per_thread->thread;
  99     if(all_threads) {
 100         memcpy(per_thread,arch_os_get_current_thread(),
 101                dynamic_values_bytes);
 102     } else {
 103 #ifdef LISP_FEATURE_SB_THREAD
 104         int i;
 105         for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
 106             per_thread->dynamic_values[i]=UNBOUND_MARKER_WIDETAG;
 107         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG)
 108             SetSymbolValue
 109                 (FREE_TLS_INDEX,
 110                  make_fixnum(MAX_INTERRUPTS+
 111                              sizeof(struct thread)/sizeof(lispobj)),
 112                  0);
 113 #define STATIC_TLS_INIT(sym,field) \
 114   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 115   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 116
 117         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 118         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 119         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 120         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 121         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 122 #ifdef LISP_FEATURE_X86
 123         STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
 124         STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
 125 #endif
 126 #undef STATIC_TLS_INIT
 127 #endif
 128     }
 129
 130     th->control_stack_start = spaces;
 131     th->binding_stack_start=
 132         (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
 133     th->control_stack_end = th->binding_stack_start;
 134     th->alien_stack_start=
 135         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 136     th->binding_stack_pointer=th->binding_stack_start;
 137     th->this=th;
 138     th->pid=0;
 139     th->state=STATE_RUNNING;
 140 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 141     th->alien_stack_pointer=((void *)th->alien_stack_start
 142                              + ALIEN_STACK_SIZE-4); /* naked 4.  FIXME */
 143 #else
 144     th->alien_stack_pointer=((void *)th->alien_stack_start);
 145 #endif
 146 #ifdef LISP_FEATURE_X86
 147     th->pseudo_atomic_interrupted=0;
 148     /* runtime.c used to set PSEUDO_ATOMIC_ATOMIC =1 globally.  I'm not
 149      * sure why, but it appears to help */
 150     th->pseudo_atomic_atomic=make_fixnum(1);
 151 #endif
 152 #ifdef LISP_FEATURE_GENCGC
 153     gc_set_region_empty(&th->alloc_region);
 154 #endif
 155
 156 #ifndef LISP_FEATURE_SB_THREAD
 157     /* the tls-points-into-struct-thread trick is only good for threaded
 158      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 159      * appropriate values from struct thread here, and make sure that
 160      * we use the appropriate SymbolValue macros to access any of the
 161      * variable quantities from the C runtime.  It's not quite OAOOM,
 162      * it just feels like it */
 163     SetSymbolValue(BINDING_STACK_START,th->binding_stack_start,th);
 164     SetSymbolValue(CONTROL_STACK_START,th->control_stack_start,th);
 165     SetSymbolValue(CONTROL_STACK_END,th->control_stack_end,th);
 166 #ifdef LISP_FEATURE_X86
 167     SetSymbolValue(BINDING_STACK_POINTER,th->binding_stack_pointer,th);
 168     SetSymbolValue(ALIEN_STACK,th->alien_stack_pointer,th);
 169     SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,th->pseudo_atomic_atomic,th);
 170     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
 171 #else
 172     current_binding_stack_pointer=th->binding_stack_pointer;
 173     current_control_stack_pointer=th->control_stack_start;
 174 #endif
 175 #endif
 176     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 177     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 178     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 179     bind_variable(INTERRUPT_PENDING, NIL,th);
 180     bind_variable(INTERRUPTS_ENABLED,T,th);
 181
 182     th->interrupt_data=os_validate(0,(sizeof (struct interrupt_data)));
 183     if(all_threads)
 184         memcpy(th->interrupt_data,
 185                arch_os_get_current_thread()->interrupt_data,
 186                sizeof (struct interrupt_data));
 187     else
 188         memcpy(th->interrupt_data,global_interrupt_data,
 189                sizeof (struct interrupt_data));
 190
 191     th->unbound_marker=initial_function;
 192 #ifdef LISP_FEATURE_SB_THREAD
 193 #if defined(LISP_FEATURE_X86) && defined (LISP_FEATURE_LINUX)
 194     kid_pid=
 195         clone(new_thread_trampoline,
 196               (((void*)th->control_stack_start)+THREAD_CONTROL_STACK_SIZE-4),
 197               (((getpid()!=parent_pid)?(CLONE_PARENT):0)
 198                |CLONE_FILES|SIGALRM|CLONE_VM),th);
 199     if(kid_pid<=0)
 200         goto cleanup;
 201 #else
 202 #error this stuff presently only works on x86 Linux
 203 #endif
 204 #else
 205     kid_pid=getpid();
 206 #endif
 207     get_spinlock(&all_threads_lock,kid_pid);
 208     th->next=all_threads;
 209     all_threads=th;
 210     /* note that th->pid is 0 at this time.  We rely on all_threads_lock
 211      * to ensure that we don't have >1 thread with pid=0 on the list at once
 212      */
 213     protect_control_stack_guard_page(th->pid,1);
 214     release_spinlock(&all_threads_lock);
 215     th->pid=kid_pid;            /* child will not start until this is set */
 216 #ifndef LISP_FEATURE_SB_THREAD
 217     new_thread_trampoline(all_threads); /*  call_into_lisp */
 218     lose("Clever child?  Idiot savant, verging on the.");
 219 #endif
 220
 221     return th->pid;
 222  cleanup:
 223     /* if(th && th->tls_cookie>=0) os_free_tls_pointer(th); */
 224     if(spaces) os_invalidate(spaces,
 225                              THREAD_CONTROL_STACK_SIZE+BINDING_STACK_SIZE+
 226                              ALIEN_STACK_SIZE+dynamic_values_bytes);
 227     return 0;
 228 }
 229
 230 void destroy_thread (struct thread *th)
 231 {
 232     /* precondition: the unix task has already been killed and exited.
 233      * This is called by the parent */
 234 #ifdef LISP_FEATURE_GENCGC
 235     gc_alloc_update_page_tables(0, &th->alloc_region);
 236 #endif
 237     get_spinlock(&all_threads_lock,th->pid);
 238     if(countdown_to_gc>0) countdown_to_gc--;
 239     th->state=STATE_STOPPED;
 240     if(th==all_threads)
 241         all_threads=th->next;
 242     else {
 243         struct thread *th1=all_threads;
 244         while(th1->next!=th) th1=th1->next;
 245         th1->next=th->next;     /* unlink */
 246     }
 247     release_spinlock(&all_threads_lock);
 248     if(th && th->tls_cookie>=0) arch_os_thread_cleanup(th);
 249     os_invalidate((os_vm_address_t) th->control_stack_start,
 250                   ((sizeof (lispobj))
 251                    * (th->control_stack_end-th->control_stack_start)) +
 252                   BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
 253                   32*SIGSTKSZ);
 254 }
 255
 256
 257 struct thread *find_thread_by_pid(pid_t pid)
 258 {
 259     struct thread *th;
 260     for_each_thread(th)
 261         if(th->pid==pid) return th;
 262     return 0;
 263 }
 264
 265 /* These are not needed unless #+SB-THREAD, and since sigwaitinfo()
 266  * doesn't seem to be easily available everywhere (OpenBSD...) it's
 267  * more trouble than it's worth to compile it when not needed. */
 268 #if defined LISP_FEATURE_SB_THREAD
 269 void block_sigcont(void)
 270 {
 271     /* don't allow ourselves to receive SIGCONT while we're in the
 272      * "ambiguous" state of being on the queue but not actually stopped.
 273      */
 274     sigset_t newset;
 275     sigemptyset(&newset);
 276     sigaddset(&newset,SIG_DEQUEUE);
 277     sigprocmask(SIG_BLOCK, &newset, 0);
 278 }
 279
 280 void unblock_sigcont_and_sleep(void)
 281 {
 282     sigset_t set;
 283     sigemptyset(&set);
 284     sigaddset(&set,SIG_DEQUEUE);
 285     do {
 286         errno=0;
 287         sigwaitinfo(&set,0);
 288     }while(errno==EINTR);
 289     sigprocmask(SIG_UNBLOCK,&set,0);
 290 }
 291
 292 int interrupt_thread(pid_t pid, lispobj function)
 293 {
 294     union sigval sigval;
 295     sigval.sival_int=function;
 296
 297     return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
 298 }
 299
 300 /* stopping the world is a two-stage process.  From this thread we signal
 301  * all the others with SIG_STOP_FOR_GC.  The handler for this thread does
 302  * the usual pseudo-atomic checks (we don't want to stop a thread while
 303  * it's in the middle of allocation) then kills _itself_ with SIGSTOP.
 304  * At any given time, countdown_to_gc should reflect the number of threads
 305  * signalled but which haven't yet come to rest
 306  */
 307
 308 void gc_stop_the_world()
 309 {
 310     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 311     struct thread *p,*th=arch_os_get_current_thread();
 312     struct thread *tail=0;
 313     int finished=0;
 314     do {
 315         get_spinlock(&all_threads_lock,th->pid);
 316         if(tail!=all_threads) {
 317             /* new threads always get consed onto the front of all_threads,
 318              * and may be created by any thread that we haven't signalled
 319              * yet or hasn't received our signal and stopped yet.  So, check
 320              * for them on each time around */
 321             for(p=all_threads;p!=tail;p=p->next) {
 322                 if(p==th) continue;
 323                 /* if the head of all_threads is removed during
 324                  * gc_stop_the_world, we may take a second trip through the
 325                  * list and end up counting twice as many threads to wait for
 326                  * as actually exist */
 327                 if(p->state!=STATE_RUNNING) continue;
 328                 countdown_to_gc++;
 329                 p->state=STATE_STOPPING;
 330                 /* Note no return value check from kill().  If the
 331                  * thread had been reaped already, we kill it and
 332                  * increment countdown_to_gc anyway.  This is to avoid
 333                  * complicating the logic in destroy_thread, which would
 334                  * otherwise have to know whether the thread died before or
 335                  * after it was killed
 336                  */
 337                 kill(p->pid,SIG_STOP_FOR_GC);
 338             }
 339             tail=all_threads;
 340         } else {
 341             finished=(countdown_to_gc==0);
 342         }
 343         release_spinlock(&all_threads_lock);
 344         sched_yield();
 345     } while(!finished);
 346 }
 347
 348 void gc_start_the_world()
 349 {
 350     struct thread *p,*th=arch_os_get_current_thread();
 351     get_spinlock(&all_threads_lock,th->pid);
 352     for(p=all_threads;p;p=p->next) {
 353         if(p==th) continue;
 354         p->state=STATE_RUNNING;
 355         kill(p->pid,SIGCONT);
 356     }
 357     release_spinlock(&all_threads_lock);
 358 }
 359 #endif