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 #ifdef LISP_FEATURE_GENCGC
  19 #include "gencgc.h"
  20 #endif
  21 #include "dynbind.h"
  22 #include "genesis/cons.h"
  23 #define ALIEN_STACK_SIZE (1*1024*1024) /* 1Mb size chosen at random */
  24
  25 int dynamic_values_bytes=4096*sizeof(lispobj);  /* same for all threads */
  26 struct thread *all_threads;
  27 volatile lispobj all_threads_lock;
  28 volatile int countdown_to_gc;
  29 extern struct interrupt_data * global_interrupt_data;
  30
  31 void get_spinlock(lispobj *word,int value);
  32
  33 /* this is the first thing that clone() runs in the child (which is
  34  * why the silly calling convention).  Basically it calls the user's
  35  * requested lisp function after doing arch_os_thread_init and
  36  * whatever other bookkeeping needs to be done
  37  */
  38
  39 /* set go to 0 to stop the thread before it starts.  Convenient if you
  40 * want to attach a debugger to it before it does anything */
  41 volatile int go=1;
  42
  43 int
  44 new_thread_trampoline(struct thread *th)
  45 {
  46     lispobj function;
  47     lispobj *args = NULL;
  48     function = th->unbound_marker;
  49     if(go==0) {
  50         fprintf(stderr, "/pausing 0x%lx(%d,%d) before new_thread_trampoline(0x%lx)\n",
  51                 (unsigned long)th,th->pid,getpid(),(unsigned long)function);
  52         while(go==0) ;
  53         fprintf(stderr, "/continue\n");
  54     }
  55     th->unbound_marker = UNBOUND_MARKER_WIDETAG;
  56 #ifdef LISP_FEATURE_SB_THREAD
  57     /* wait here until our thread is linked into all_threads: see below */
  58     while(th->pid<1) sched_yield();
  59 #else
  60     if(th->pid < 1)
  61         lose("th->pid not set up right");
  62 #endif
  63
  64     if(arch_os_thread_init(th)==0)
  65         return 1;               /* failure.  no, really */
  66 #if !defined(LISP_FEATURE_SB_THREAD) && defined(LISP_FEATURE_X86)
  67     return call_into_lisp_first_time(function,args,0);
  68 #else
  69     return funcall0(function);
  70 #endif
  71 }
  72
  73 /* this is called from any other thread to create the new one, and
  74  * initialize all parts of it that can be initialized from another
  75  * thread
  76  */
  77
  78 pid_t create_thread(lispobj initial_function) {
  79     union per_thread_data *per_thread;
  80     struct thread *th=0;        /*  subdue gcc */
  81     void *spaces=0;
  82     pid_t kid_pid;
  83
  84     /* may as well allocate all the spaces at once: it saves us from
  85      * having to decide what to do if only some of the allocations
  86      * succeed */
  87     spaces=os_validate(0,
  88                        THREAD_CONTROL_STACK_SIZE+
  89                        BINDING_STACK_SIZE+
  90                        ALIEN_STACK_SIZE+
  91                        dynamic_values_bytes+
  92                        32*SIGSTKSZ
  93                        );
  94     if(!spaces) goto cleanup;
  95     per_thread=(union per_thread_data *)
  96         (spaces+
  97          THREAD_CONTROL_STACK_SIZE+
  98          BINDING_STACK_SIZE+
  99          ALIEN_STACK_SIZE);
 100
 101     th=&per_thread->thread;
 102     if(all_threads) {
 103         memcpy(per_thread,arch_os_get_current_thread(),
 104                dynamic_values_bytes);
 105     } else {
 106 #ifdef LISP_FEATURE_SB_THREAD
 107         int i;
 108         for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
 109             per_thread->dynamic_values[i]=UNBOUND_MARKER_WIDETAG;
 110         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG)
 111             SetSymbolValue
 112                 (FREE_TLS_INDEX,
 113                  make_fixnum(MAX_INTERRUPTS+
 114                              sizeof(struct thread)/sizeof(lispobj)),
 115                  0);
 116 #define STATIC_TLS_INIT(sym,field) \
 117   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 118   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 119
 120         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 121         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 122         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 123         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 124         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 125 #ifdef LISP_FEATURE_X86
 126         STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
 127         STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
 128 #endif
 129 #undef STATIC_TLS_INIT
 130 #endif
 131     }
 132
 133     th->control_stack_start = spaces;
 134     th->binding_stack_start=
 135         (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
 136     th->control_stack_end = th->binding_stack_start;
 137     th->alien_stack_start=
 138         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 139     th->binding_stack_pointer=th->binding_stack_start;
 140     th->this=th;
 141     th->pid=0;
 142     th->state=STATE_RUNNING;
 143 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 144     th->alien_stack_pointer=((void *)th->alien_stack_start
 145                              + ALIEN_STACK_SIZE-4); /* naked 4.  FIXME */
 146 #else
 147     th->alien_stack_pointer=((void *)th->alien_stack_start);
 148 #endif
 149 #ifdef LISP_FEATURE_X86
 150     th->pseudo_atomic_interrupted=0;
 151     /* runtime.c used to set PSEUDO_ATOMIC_ATOMIC =1 globally.  I'm not
 152      * sure why, but it appears to help */
 153     th->pseudo_atomic_atomic=make_fixnum(1);
 154 #endif
 155 #ifdef LISP_FEATURE_GENCGC
 156     gc_set_region_empty(&th->alloc_region);
 157 #endif
 158
 159 #ifndef LISP_FEATURE_SB_THREAD
 160     /* the tls-points-into-struct-thread trick is only good for threaded
 161      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 162      * appropriate values from struct thread here, and make sure that
 163      * we use the appropriate SymbolValue macros to access any of the
 164      * variable quantities from the C runtime.  It's not quite OAOOM,
 165      * it just feels like it */
 166     SetSymbolValue(BINDING_STACK_START,th->binding_stack_start,th);
 167     SetSymbolValue(CONTROL_STACK_START,th->control_stack_start,th);
 168     SetSymbolValue(CONTROL_STACK_END,th->control_stack_end,th);
 169 #ifdef LISP_FEATURE_X86
 170     SetSymbolValue(BINDING_STACK_POINTER,th->binding_stack_pointer,th);
 171     SetSymbolValue(ALIEN_STACK,th->alien_stack_pointer,th);
 172     SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,th->pseudo_atomic_atomic,th);
 173     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
 174 #else
 175     current_binding_stack_pointer=th->binding_stack_pointer;
 176     current_control_stack_pointer=th->control_stack_start;
 177 #endif
 178 #endif
 179     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 180     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 181     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 182     bind_variable(INTERRUPT_PENDING, NIL,th);
 183     bind_variable(INTERRUPTS_ENABLED,T,th);
 184
 185     th->interrupt_data=os_validate(0,(sizeof (struct interrupt_data)));
 186     if(all_threads)
 187         memcpy(th->interrupt_data,
 188                arch_os_get_current_thread()->interrupt_data,
 189                sizeof (struct interrupt_data));
 190     else
 191         memcpy(th->interrupt_data,global_interrupt_data,
 192                sizeof (struct interrupt_data));
 193
 194     th->unbound_marker=initial_function;
 195 #ifdef LISP_FEATURE_SB_THREAD
 196 #if defined(LISP_FEATURE_X86) && defined (LISP_FEATURE_LINUX)
 197     kid_pid=
 198         clone(new_thread_trampoline,
 199               (((void*)th->control_stack_start)+THREAD_CONTROL_STACK_SIZE-4),
 200               (((getpid()!=parent_pid)?(CLONE_PARENT):0)
 201                |CLONE_FILES|SIGALRM|CLONE_VM),th);
 202     if(kid_pid<=0)
 203         goto cleanup;
 204 #else
 205 #error this stuff presently only works on x86 Linux
 206 #endif
 207 #else
 208     kid_pid=getpid();
 209 #endif
 210     get_spinlock(&all_threads_lock,kid_pid);
 211     th->next=all_threads;
 212     all_threads=th;
 213     /* note that th->pid is 0 at this time.  We rely on all_threads_lock
 214      * to ensure that we don't have >1 thread with pid=0 on the list at once
 215      */
 216     protect_control_stack_guard_page(th->pid,1);
 217     release_spinlock(&all_threads_lock);
 218     th->pid=kid_pid;            /* child will not start until this is set */
 219 #ifndef LISP_FEATURE_SB_THREAD
 220     new_thread_trampoline(all_threads); /*  call_into_lisp */
 221     lose("Clever child?  Idiot savant, verging on the.");
 222 #endif
 223
 224     return th->pid;
 225  cleanup:
 226     /* if(th && th->tls_cookie>=0) os_free_tls_pointer(th); */
 227     if(spaces) os_invalidate(spaces,
 228                              THREAD_CONTROL_STACK_SIZE+BINDING_STACK_SIZE+
 229                              ALIEN_STACK_SIZE+dynamic_values_bytes);
 230     return 0;
 231 }
 232
 233 void destroy_thread (struct thread *th)
 234 {
 235     /* precondition: the unix task has already been killed and exited.
 236      * This is called by the parent */
 237 #ifdef LISP_FEATURE_GENCGC
 238     gc_alloc_update_page_tables(0, &th->alloc_region);
 239 #endif
 240     get_spinlock(&all_threads_lock,th->pid);
 241     if(countdown_to_gc>0) countdown_to_gc--;
 242     th->state=STATE_STOPPED;
 243     if(th==all_threads)
 244         all_threads=th->next;
 245     else {
 246         struct thread *th1=all_threads;
 247         while(th1->next!=th) th1=th1->next;
 248         th1->next=th->next;     /* unlink */
 249     }
 250     release_spinlock(&all_threads_lock);
 251     if(th && th->tls_cookie>=0) arch_os_thread_cleanup(th);
 252     os_invalidate((os_vm_address_t) th->control_stack_start,
 253                   ((sizeof (lispobj))
 254                    * (th->control_stack_end-th->control_stack_start)) +
 255                   BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
 256                   32*SIGSTKSZ);
 257 }
 258
 259
 260 struct thread *find_thread_by_pid(pid_t pid)
 261 {
 262     struct thread *th;
 263     for_each_thread(th)
 264         if(th->pid==pid) return th;
 265     return 0;
 266 }
 267
 268 /* These are not needed unless #+SB-THREAD, and since sigwaitinfo()
 269  * doesn't seem to be easily available everywhere (OpenBSD...) it's
 270  * more trouble than it's worth to compile it when not needed. */
 271 #if defined LISP_FEATURE_SB_THREAD
 272 void block_sigcont(void)
 273 {
 274     /* don't allow ourselves to receive SIGCONT while we're in the
 275      * "ambiguous" state of being on the queue but not actually stopped.
 276      */
 277     sigset_t newset;
 278     sigemptyset(&newset);
 279     sigaddset(&newset,SIG_DEQUEUE);
 280     sigprocmask(SIG_BLOCK, &newset, 0);
 281 }
 282
 283 void unblock_sigcont_and_sleep(void)
 284 {
 285     sigset_t set;
 286     sigemptyset(&set);
 287     sigaddset(&set,SIG_DEQUEUE);
 288     do {
 289         errno=0;
 290         sigwaitinfo(&set,0);
 291     }while(errno==EINTR);
 292     sigprocmask(SIG_UNBLOCK,&set,0);
 293 }
 294
 295 int interrupt_thread(pid_t pid, lispobj function)
 296 {
 297     union sigval sigval;
 298     sigval.sival_int=function;
 299
 300     return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
 301 }
 302
 303 /* stopping the world is a two-stage process.  From this thread we signal
 304  * all the others with SIG_STOP_FOR_GC.  The handler for this thread does
 305  * the usual pseudo-atomic checks (we don't want to stop a thread while
 306  * it's in the middle of allocation) then kills _itself_ with SIGSTOP.
 307  * At any given time, countdown_to_gc should reflect the number of threads
 308  * signalled but which haven't yet come to rest
 309  */
 310
 311 void gc_stop_the_world()
 312 {
 313     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 314     struct thread *p,*th=arch_os_get_current_thread();
 315     struct thread *tail=0;
 316     int finished=0;
 317     do {
 318         get_spinlock(&all_threads_lock,th->pid);
 319         if(tail!=all_threads) {
 320             /* new threads always get consed onto the front of all_threads,
 321              * and may be created by any thread that we haven't signalled
 322              * yet or hasn't received our signal and stopped yet.  So, check
 323              * for them on each time around */
 324             for(p=all_threads;p!=tail;p=p->next) {
 325                 if(p==th) continue;
 326                 /* if the head of all_threads is removed during
 327                  * gc_stop_the_world, we may take a second trip through the
 328                  * list and end up counting twice as many threads to wait for
 329                  * as actually exist */
 330                 if(p->state!=STATE_RUNNING) continue;
 331                 countdown_to_gc++;
 332                 p->state=STATE_STOPPING;
 333                 /* Note no return value check from kill().  If the
 334                  * thread had been reaped already, we kill it and
 335                  * increment countdown_to_gc anyway.  This is to avoid
 336                  * complicating the logic in destroy_thread, which would
 337                  * otherwise have to know whether the thread died before or
 338                  * after it was killed
 339                  */
 340                 kill(p->pid,SIG_STOP_FOR_GC);
 341             }
 342             tail=all_threads;
 343         } else {
 344             finished=(countdown_to_gc==0);
 345         }
 346         release_spinlock(&all_threads_lock);
 347         sched_yield();
 348     } while(!finished);
 349 }
 350
 351 void gc_start_the_world()
 352 {
 353     struct thread *p,*th=arch_os_get_current_thread();
 354     get_spinlock(&all_threads_lock,th->pid);
 355     for(p=all_threads;p;p=p->next) {
 356         if(p==th) continue;
 357         p->state=STATE_RUNNING;
 358         kill(p->pid,SIGCONT);
 359     }
 360     release_spinlock(&all_threads_lock);
 361 }
 362 #endif