source: src/libcfa/concurrency/preemption.c@ d6ff3ff

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 d6ff3ff was d6ff3ff, checked in by Thierry Delisle <tdelisle@…>, 8 years ago

Kernel shoud now drop preemptions during other preemptions
  • Property mode set to 100644
File size: 11.6 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 && !preemption_in_progress;
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 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopping\n");
221
222 sigset_t mask;
223 sigfillset( &mask );
224 sigprocmask( SIG_BLOCK, &mask, NULL );
225
226 sigval val = { 1 };
227 pthread_sigqueue( alarm_thread, SIGALRM, val );
228 pthread_join( alarm_thread, NULL );
229 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopped\n");
230}
231
232void ?{}( preemption_scope * this, processor * proc ) {
233 (&this->alarm){ proc };
234 this->proc = proc;
235 this->proc->preemption_alarm = &this->alarm;
236 update_preemption( this->proc, this->proc->preemption );
237}
238
239void ^?{}( preemption_scope * this ) {
240 disable_interrupts();
241
242 update_preemption( this->proc, 0 );
243}
244
245//=============================================================================================
246// Kernel Signal Handlers
247//=============================================================================================
248
249void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) {
250 LIB_DEBUG_DO( last_interrupt = (void *)(cxt->uc_mcontext.gregs[CFA_REG_IP]); )
251 if( preemption_ready() ) {
252 preemption_in_progress = true;
253 signal_unblock( SIGUSR1 );
254 this_processor->pending_preemption = false;
255 preemption_in_progress = false;
256 BlockInternal( (thread_desc*)this_thread );
257 }
258 else {
259 defer_ctxSwitch();
260 }
261}
262
263void * alarm_loop( __attribute__((unused)) void * args ) {
264 sigset_t mask;
265 sigemptyset( &mask );
266 sigaddset( &mask, SIGALRM );
267
268 if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) {
269 abortf( "internal error, pthread_sigmask" );
270 }
271
272 while( true ) {
273 siginfo_t info;
274 int sig = sigwaitinfo( &mask, &info );
275 if( sig < 0 ) {
276 abortf( "internal error, sigwait" );
277 }
278 else if( sig == SIGALRM )
279 {
280 LIB_DEBUG_PRINT_SAFE("Kernel : Caught signal %d (%d)\n", sig, info.si_value.sival_int );
281 if( info.si_value.sival_int == 0 )
282 {
283 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread tick\n");
284 lock( &systemProcessor->alarm_lock DEBUG_CTX2 );
285 tick_preemption();
286 unlock( &systemProcessor->alarm_lock );
287 }
288 else if( info.si_value.sival_int == 1 )
289 {
290 break;
291 }
292 }
293 else
294 {
295 LIB_DEBUG_PRINT_SAFE("Kernel : Unexpected signal %d (%d)\n", sig, info.si_value.sival_int);
296 }
297 }
298
299 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread stopping\n");
300 return NULL;
301}
302
303static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags ) {
304 struct sigaction act;
305
306 act.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
307 act.sa_flags = flags;
308
309 if ( sigaction( sig, &act, NULL ) == -1 ) {
310 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
311 " __kernel_sigaction( sig:%d, handler:%p, flags:%d ), problem installing signal handler, error(%d) %s.\n",
312 sig, handler, flags, errno, strerror( errno )
313 );
314 _exit( EXIT_FAILURE );
315 }
316}
317
318typedef void (*sa_handler_t)(int);
319
320static void __kernel_sigdefault( int sig ) {
321 struct sigaction act;
322
323 // act.sa_handler = SIG_DFL;
324 act.sa_flags = 0;
325 sigemptyset( &act.sa_mask );
326
327 if ( sigaction( sig, &act, NULL ) == -1 ) {
328 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
329 " __kernel_sigdefault( sig:%d ), problem reseting signal handler, error(%d) %s.\n",
330 sig, errno, strerror( errno )
331 );
332 _exit( EXIT_FAILURE );
333 }
334}
335
336//=============================================================================================
337// Terminating Signals logic
338//=============================================================================================
339
340LIB_DEBUG_DO(
341 static void __kernel_backtrace( int start ) {
342 // skip first N stack frames
343
344 enum { Frames = 50 };
345 void * array[Frames];
346 int size = backtrace( array, Frames );
347 char ** messages = backtrace_symbols( array, size );
348
349 // find executable name
350 *index( messages[0], '(' ) = '\0';
351 #ifdef __USE_STREAM__
352 serr | "Stack back trace for:" | messages[0] | endl;
353 #else
354 fprintf( stderr, "Stack back trace for: %s\n", messages[0]);
355 #endif
356
357 // skip last 2 stack frames after main
358 for ( int i = start; i < size && messages != NULL; i += 1 ) {
359 char * name = NULL;
360 char * offset_begin = NULL;
361 char * offset_end = NULL;
362
363 for ( char *p = messages[i]; *p; ++p ) {
364 // find parantheses and +offset
365 if ( *p == '(' ) {
366 name = p;
367 }
368 else if ( *p == '+' ) {
369 offset_begin = p;
370 }
371 else if ( *p == ')' ) {
372 offset_end = p;
373 break;
374 }
375 }
376
377 // if line contains symbol print it
378 int frameNo = i - start;
379 if ( name && offset_begin && offset_end && name < offset_begin ) {
380 // delimit strings
381 *name++ = '\0';
382 *offset_begin++ = '\0';
383 *offset_end++ = '\0';
384
385 #ifdef __USE_STREAM__
386 serr | "(" | frameNo | ")" | messages[i] | ":"
387 | name | "+" | offset_begin | offset_end | endl;
388 #else
389 fprintf( stderr, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
390 #endif
391 }
392 // otherwise, print the whole line
393 else {
394 #ifdef __USE_STREAM__
395 serr | "(" | frameNo | ")" | messages[i] | endl;
396 #else
397 fprintf( stderr, "(%i) %s\n", frameNo, messages[i] );
398 #endif
399 }
400 }
401
402 free( messages );
403 }
404)
405
406// void sigHandler_segv( __CFA_SIGPARMS__ ) {
407// LIB_DEBUG_DO(
408// #ifdef __USE_STREAM__
409// serr | "*CFA runtime error* program cfa-cpp terminated with"
410// | (sig == SIGSEGV ? "segment fault." : "bus error.")
411// | endl;
412// #else
413// fprintf( stderr, "*CFA runtime error* program cfa-cpp terminated with %s\n", sig == SIGSEGV ? "segment fault." : "bus error." );
414// #endif
415
416// // skip first 2 stack frames
417// __kernel_backtrace( 1 );
418// )
419// exit( EXIT_FAILURE );
420// }
421
422// void sigHandler_abort( __CFA_SIGPARMS__ ) {
423// // skip first 6 stack frames
424// LIB_DEBUG_DO( __kernel_backtrace( 6 ); )
425
426// // reset default signal handler
427// __kernel_sigdefault( SIGABRT );
428
429// raise( SIGABRT );
430// }
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