source: src/libcfa/concurrency/preemption.c@ b877fa8

ADT aaron-thesis arm-eh ast-experimental cleanup-dtors deferred_resn demangler enum forall-pointer-decay jacob/cs343-translation jenkins-sandbox new-ast new-ast-unique-expr new-env no_list persistent-indexer pthread-emulation qualifiedEnum resolv-new with_gc
Last change on this file since b877fa8 was cd17862, checked in by Thierry Delisle <tdelisle@…>, 8 years ago

Preemption now uses an oracle kernel thread
  • Property mode set to 100644
File size: 11.8 KB
Line 
1// -*- Mode: CFA -*-
2//
3// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
4//
5// The contents of this file are covered under the licence agreement in the
6// file "LICENCE" distributed with Cforall.
7//
8// signal.c --
9//
10// Author : Thierry Delisle
11// Created On : Mon Jun 5 14:20:42 2017
12// Last Modified By : Thierry Delisle
13// Last Modified On : --
14// Update Count : 0
15//
16
17#include "libhdr.h"
18#include "preemption.h"
19
20extern "C" {
21#include <errno.h>
22#include <execinfo.h>
23#define __USE_GNU
24#include <signal.h>
25#undef __USE_GNU
26#include <stdio.h>
27#include <string.h>
28#include <unistd.h>
29}
30
31
32#ifdef __USE_STREAM__
33#include "fstream"
34#endif
35
36#define __CFA_DEFAULT_PREEMPTION__ 10000
37
38__attribute__((weak)) unsigned int default_preemption() {
39 return __CFA_DEFAULT_PREEMPTION__;
40}
41
42#define __CFA_SIGCXT__ ucontext_t *
43#define __CFA_SIGPARMS__ __attribute__((unused)) int sig, __attribute__((unused)) siginfo_t *sfp, __attribute__((unused)) __CFA_SIGCXT__ cxt
44
45static void preempt( processor * this );
46static void timeout( thread_desc * this );
47
48void sigHandler_ctxSwitch( __CFA_SIGPARMS__ );
49void sigHandler_alarm ( __CFA_SIGPARMS__ );
50void sigHandler_segv ( __CFA_SIGPARMS__ );
51void sigHandler_abort ( __CFA_SIGPARMS__ );
52
53static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags );
54LIB_DEBUG_DO( bool validate( alarm_list_t * this ); )
55
56#ifdef __x86_64__
57#define CFA_REG_IP REG_RIP
58#else
59#define CFA_REG_IP REG_EIP
60#endif
61
62
63//=============================================================================================
64// Kernel Preemption logic
65//=============================================================================================
66
67void tick_preemption() {
68 // LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO, "Ticking preemption\n" );
69
70 alarm_list_t * alarms = &systemProcessor->alarms;
71 __cfa_time_t currtime = __kernel_get_time();
72 while( alarms->head && alarms->head->alarm < currtime ) {
73 alarm_node_t * node = pop(alarms);
74 // LIB_DEBUG_PRINT_BUFFER_LOCAL( STDERR_FILENO, "Ticking %p\n", node );
75
76 if( node->kernel_alarm ) {
77 preempt( node->proc );
78 }
79 else {
80 timeout( node->thrd );
81 }
82
83 verify( validate( alarms ) );
84
85 if( node->period > 0 ) {
86 node->alarm = currtime + node->period;
87 insert( alarms, node );
88 }
89 else {
90 node->set = false;
91 }
92 }
93
94 if( alarms->head ) {
95 __kernel_set_timer( alarms->head->alarm - currtime );
96 }
97
98 verify( validate( alarms ) );
99 // LIB_DEBUG_PRINT_BUFFER_LOCAL( STDERR_FILENO, "Ticking preemption done\n" );
100}
101
102void update_preemption( processor * this, __cfa_time_t duration ) {
103 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO, "Processor : %p updating preemption to %lu\n", this, duration );
104
105 alarm_node_t * alarm = this->preemption_alarm;
106 duration *= 1000;
107
108 // Alarms need to be enabled
109 if ( duration > 0 && !alarm->set ) {
110 alarm->alarm = __kernel_get_time() + duration;
111 alarm->period = duration;
112 register_self( alarm );
113 }
114 // Zero duraction but alarm is set
115 else if ( duration == 0 && alarm->set ) {
116 unregister_self( alarm );
117 alarm->alarm = 0;
118 alarm->period = 0;
119 }
120 // If alarm is different from previous, change it
121 else if ( duration > 0 && alarm->period != duration ) {
122 unregister_self( alarm );
123 alarm->alarm = __kernel_get_time() + duration;
124 alarm->period = duration;
125 register_self( alarm );
126 }
127}
128
129//=============================================================================================
130// Kernel Signal Tools
131//=============================================================================================
132
133LIB_DEBUG_DO( static thread_local void * last_interrupt = 0; )
134
135extern "C" {
136 void disable_interrupts() {
137 __attribute__((unused)) unsigned short new_val = __atomic_add_fetch_2( &disable_preempt_count, 1, __ATOMIC_SEQ_CST );
138 verify( new_val < (unsigned short)65_000 );
139 verify( new_val != (unsigned short) 0 );
140 }
141
142 void enable_interrupts_noRF() {
143 __attribute__((unused)) unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
144 verify( prev != (unsigned short) 0 );
145 }
146
147 void enable_interrupts( DEBUG_CTX_PARAM ) {
148 processor * proc = this_processor;
149 thread_desc * thrd = this_thread;
150 unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
151 verify( prev != (unsigned short) 0 );
152 if( prev == 1 && proc->pending_preemption ) {
153 proc->pending_preemption = false;
154 BlockInternal( thrd );
155 }
156
157 LIB_DEBUG_DO( proc->last_enable = caller; )
158 }
159}
160
161static inline void signal_unblock( int sig ) {
162 sigset_t mask;
163 sigemptyset( &mask );
164 sigaddset( &mask, sig );
165
166 if ( pthread_sigmask( SIG_UNBLOCK, &mask, NULL ) == -1 ) {
167 abortf( "internal error, pthread_sigmask" );
168 }
169}
170
171static inline void signal_block( int sig ) {
172 sigset_t mask;
173 sigemptyset( &mask );
174 sigaddset( &mask, sig );
175
176 if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) {
177 abortf( "internal error, pthread_sigmask" );
178 }
179}
180
181static inline bool preemption_ready() {
182 return disable_preempt_count == 0;
183}
184
185static inline void defer_ctxSwitch() {
186 this_processor->pending_preemption = true;
187}
188
189static inline void defer_alarm() {
190 systemProcessor->pending_alarm = true;
191}
192
193static void preempt( processor * this ) {
194 pthread_kill( this->kernel_thread, SIGUSR1 );
195}
196
197static void timeout( thread_desc * this ) {
198 //TODO : implement waking threads
199}
200
201//=============================================================================================
202// Kernel Signal Startup/Shutdown logic
203//=============================================================================================
204
205static pthread_t alarm_thread;
206void * alarm_loop( __attribute__((unused)) void * args );
207
208void kernel_start_preemption() {
209 LIB_DEBUG_PRINT_SAFE("Kernel : Starting preemption\n");
210 __kernel_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO );
211 __kernel_sigaction( SIGSEGV, sigHandler_segv , SA_SIGINFO );
212 __kernel_sigaction( SIGBUS , sigHandler_segv , SA_SIGINFO );
213
214 signal_block( SIGALRM );
215
216 pthread_create( &alarm_thread, NULL, alarm_loop, NULL );
217}
218
219void kernel_stop_preemption() {
220 sigset_t mask;
221 sigfillset( &mask );
222 sigprocmask( SIG_BLOCK, &mask, NULL );
223
224 pthread_kill( alarm_thread, SIGINT );
225 pthread_join( alarm_thread, NULL );
226 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopped\n");
227}
228
229void ?{}( preemption_scope * this, processor * proc ) {
230 (&this->alarm){ proc };
231 this->proc = proc;
232 this->proc->preemption_alarm = &this->alarm;
233 update_preemption( this->proc, this->proc->preemption );
234}
235
236void ^?{}( preemption_scope * this ) {
237 disable_interrupts();
238
239 update_preemption( this->proc, 0 );
240}
241
242//=============================================================================================
243// Kernel Signal Handlers
244//=============================================================================================
245
246void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) {
247 LIB_DEBUG_DO( last_interrupt = (void *)(cxt->uc_mcontext.gregs[CFA_REG_IP]); )
248 if( preemption_ready() ) {
249 signal_unblock( SIGUSR1 );
250 BlockInternal( (thread_desc*)this_thread );
251 }
252 else {
253 defer_ctxSwitch();
254 }
255}
256
257// void sigHandler_alarm( __CFA_SIGPARMS__ ) {
258// LIB_DEBUG_DO( last_interrupt = (void *)(cxt->uc_mcontext.gregs[CFA_REG_IP]); )
259// verify( this_processor == systemProcessor );
260
261// if( try_lock( &systemProcessor->alarm_lock DEBUG_CTX2 ) ) {
262// tick_preemption();
263// systemProcessor->pending_alarm = false;
264// unlock( &systemProcessor->alarm_lock );
265// }
266// else {
267// defer_alarm();
268// }
269
270// signal_unblock( SIGALRM );
271
272// if( preemption_ready() && this_processor->pending_preemption ) {
273
274// this_processor->pending_preemption = false;
275// BlockInternal( (thread_desc*)this_thread );
276// }
277// }
278
279void * alarm_loop( __attribute__((unused)) void * args ) {
280 sigset_t mask;
281 sigemptyset( &mask );
282 sigaddset( &mask, SIGALRM );
283 sigaddset( &mask, SIGUSR2 );
284 sigaddset( &mask, SIGINT );
285
286 if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) {
287 abortf( "internal error, pthread_sigmask" );
288 }
289
290 while( true ) {
291 int sig;
292 if( sigwait( &mask, &sig ) != 0 ) {
293 abortf( "internal error, sigwait" );
294 }
295
296 switch( sig) {
297 case SIGALRM:
298 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread tick\n");
299 lock( &systemProcessor->alarm_lock DEBUG_CTX2 );
300 tick_preemption();
301 unlock( &systemProcessor->alarm_lock );
302 break;
303 case SIGUSR2:
304 //TODO other actions
305 break;
306 case SIGINT:
307 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread stopping\n");
308 return NULL;
309 default:
310 abortf( "internal error, sigwait returned sig %d", sig );
311 break;
312 }
313 }
314}
315
316static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags ) {
317 struct sigaction act;
318
319 act.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
320 act.sa_flags = flags;
321
322 if ( sigaction( sig, &act, NULL ) == -1 ) {
323 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
324 " __kernel_sigaction( sig:%d, handler:%p, flags:%d ), problem installing signal handler, error(%d) %s.\n",
325 sig, handler, flags, errno, strerror( errno )
326 );
327 _exit( EXIT_FAILURE );
328 }
329}
330
331typedef void (*sa_handler_t)(int);
332
333static void __kernel_sigdefault( int sig ) {
334 struct sigaction act;
335
336 // act.sa_handler = SIG_DFL;
337 act.sa_flags = 0;
338 sigemptyset( &act.sa_mask );
339
340 if ( sigaction( sig, &act, NULL ) == -1 ) {
341 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
342 " __kernel_sigdefault( sig:%d ), problem reseting signal handler, error(%d) %s.\n",
343 sig, errno, strerror( errno )
344 );
345 _exit( EXIT_FAILURE );
346 }
347}
348
349//=============================================================================================
350// Terminating Signals logic
351//=============================================================================================
352
353LIB_DEBUG_DO(
354 static void __kernel_backtrace( int start ) {
355 // skip first N stack frames
356
357 enum { Frames = 50 };
358 void * array[Frames];
359 int size = backtrace( array, Frames );
360 char ** messages = backtrace_symbols( array, size );
361
362 // find executable name
363 *index( messages[0], '(' ) = '\0';
364 #ifdef __USE_STREAM__
365 serr | "Stack back trace for:" | messages[0] | endl;
366 #else
367 fprintf( stderr, "Stack back trace for: %s\n", messages[0]);
368 #endif
369
370 // skip last 2 stack frames after main
371 for ( int i = start; i < size && messages != NULL; i += 1 ) {
372 char * name = NULL;
373 char * offset_begin = NULL;
374 char * offset_end = NULL;
375
376 for ( char *p = messages[i]; *p; ++p ) {
377 // find parantheses and +offset
378 if ( *p == '(' ) {
379 name = p;
380 }
381 else if ( *p == '+' ) {
382 offset_begin = p;
383 }
384 else if ( *p == ')' ) {
385 offset_end = p;
386 break;
387 }
388 }
389
390 // if line contains symbol print it
391 int frameNo = i - start;
392 if ( name && offset_begin && offset_end && name < offset_begin ) {
393 // delimit strings
394 *name++ = '\0';
395 *offset_begin++ = '\0';
396 *offset_end++ = '\0';
397
398 #ifdef __USE_STREAM__
399 serr | "(" | frameNo | ")" | messages[i] | ":"
400 | name | "+" | offset_begin | offset_end | endl;
401 #else
402 fprintf( stderr, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
403 #endif
404 }
405 // otherwise, print the whole line
406 else {
407 #ifdef __USE_STREAM__
408 serr | "(" | frameNo | ")" | messages[i] | endl;
409 #else
410 fprintf( stderr, "(%i) %s\n", frameNo, messages[i] );
411 #endif
412 }
413 }
414
415 free( messages );
416 }
417)
418
419void sigHandler_segv( __CFA_SIGPARMS__ ) {
420 LIB_DEBUG_DO(
421 #ifdef __USE_STREAM__
422 serr | "*CFA runtime error* program cfa-cpp terminated with"
423 | (sig == SIGSEGV ? "segment fault." : "bus error.")
424 | endl;
425 #else
426 fprintf( stderr, "*CFA runtime error* program cfa-cpp terminated with %s\n", sig == SIGSEGV ? "segment fault." : "bus error." );
427 #endif
428
429 // skip first 2 stack frames
430 __kernel_backtrace( 1 );
431 )
432 exit( EXIT_FAILURE );
433}
434
435// void sigHandler_abort( __CFA_SIGPARMS__ ) {
436// // skip first 6 stack frames
437// LIB_DEBUG_DO( __kernel_backtrace( 6 ); )
438
439// // reset default signal handler
440// __kernel_sigdefault( SIGABRT );
441
442// raise( SIGABRT );
443// }
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