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