source: src/libcfa/concurrency/preemption.c@ ed9c0a8

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 ed9c0a8 was 8cb529e, checked in by Thierry Delisle <tdelisle@…>, 8 years ago

Preemption now properly(?) use si_code in addition to si_value
  • Property mode set to 100644
File size: 11.7 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 alarm_list_t * alarms = &systemProcessor->alarms;
69 __cfa_time_t currtime = __kernel_get_time();
70
71 // LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO, "Ticking preemption @ %llu\n", currtime );
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 __cfa_time_t period = node->period;
86 if( period > 0 ) {
87 node->alarm = currtime + period;
88 // LIB_DEBUG_PRINT_BUFFER_LOCAL( STDERR_FILENO, "Reinsert %p @ %llu (%llu + %llu)\n", node, node->alarm, currtime, period );
89 insert( alarms, node );
90 }
91 else {
92 node->set = false;
93 }
94 }
95
96 if( alarms->head ) {
97 __kernel_set_timer( alarms->head->alarm - currtime );
98 }
99
100 verify( validate( alarms ) );
101 // LIB_DEBUG_PRINT_BUFFER_LOCAL( STDERR_FILENO, "Ticking preemption done\n" );
102}
103
104void update_preemption( processor * this, __cfa_time_t duration ) {
105 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO, "Processor : %p updating preemption to %llu\n", this, duration );
106
107 alarm_node_t * alarm = this->preemption_alarm;
108 duration *= 1000;
109
110 // Alarms need to be enabled
111 if ( duration > 0 && !alarm->set ) {
112 alarm->alarm = __kernel_get_time() + duration;
113 alarm->period = duration;
114 register_self( alarm );
115 }
116 // Zero duraction but alarm is set
117 else if ( duration == 0 && alarm->set ) {
118 unregister_self( alarm );
119 alarm->alarm = 0;
120 alarm->period = 0;
121 }
122 // If alarm is different from previous, change it
123 else if ( duration > 0 && alarm->period != duration ) {
124 unregister_self( alarm );
125 alarm->alarm = __kernel_get_time() + duration;
126 alarm->period = duration;
127 register_self( alarm );
128 }
129}
130
131//=============================================================================================
132// Kernel Signal Tools
133//=============================================================================================
134
135LIB_DEBUG_DO( static thread_local void * last_interrupt = 0; )
136
137extern "C" {
138 void disable_interrupts() {
139 __attribute__((unused)) unsigned short new_val = __atomic_add_fetch_2( &disable_preempt_count, 1, __ATOMIC_SEQ_CST );
140 verify( new_val < (unsigned short)65_000 );
141 verify( new_val != (unsigned short) 0 );
142 }
143
144 void enable_interrupts_noRF() {
145 __attribute__((unused)) unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
146 verify( prev != (unsigned short) 0 );
147 }
148
149 void enable_interrupts( DEBUG_CTX_PARAM ) {
150 processor * proc = this_processor;
151 thread_desc * thrd = this_thread;
152 unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
153 verify( prev != (unsigned short) 0 );
154 if( prev == 1 && proc->pending_preemption ) {
155 proc->pending_preemption = false;
156 BlockInternal( thrd );
157 }
158
159 LIB_DEBUG_DO( proc->last_enable = caller; )
160 }
161}
162
163static inline void signal_unblock( int sig ) {
164 sigset_t mask;
165 sigemptyset( &mask );
166 sigaddset( &mask, sig );
167
168 if ( pthread_sigmask( SIG_UNBLOCK, &mask, NULL ) == -1 ) {
169 abortf( "internal error, pthread_sigmask" );
170 }
171}
172
173static inline void signal_block( int sig ) {
174 sigset_t mask;
175 sigemptyset( &mask );
176 sigaddset( &mask, sig );
177
178 if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) {
179 abortf( "internal error, pthread_sigmask" );
180 }
181}
182
183static inline bool preemption_ready() {
184 return disable_preempt_count == 0 && !preemption_in_progress;
185}
186
187static inline void defer_ctxSwitch() {
188 this_processor->pending_preemption = true;
189}
190
191static inline void defer_alarm() {
192 systemProcessor->pending_alarm = true;
193}
194
195static void preempt( processor * this ) {
196 pthread_kill( this->kernel_thread, SIGUSR1 );
197}
198
199static void timeout( thread_desc * this ) {
200 //TODO : implement waking threads
201}
202
203//=============================================================================================
204// Kernel Signal Startup/Shutdown logic
205//=============================================================================================
206
207static pthread_t alarm_thread;
208void * alarm_loop( __attribute__((unused)) void * args );
209
210void kernel_start_preemption() {
211 LIB_DEBUG_PRINT_SAFE("Kernel : Starting preemption\n");
212 __kernel_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO );
213 // __kernel_sigaction( SIGSEGV, sigHandler_segv , SA_SIGINFO );
214 // __kernel_sigaction( SIGBUS , sigHandler_segv , SA_SIGINFO );
215
216 signal_block( SIGALRM );
217
218 pthread_create( &alarm_thread, NULL, alarm_loop, NULL );
219}
220
221void kernel_stop_preemption() {
222 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopping\n");
223
224 sigset_t mask;
225 sigfillset( &mask );
226 sigprocmask( SIG_BLOCK, &mask, NULL );
227
228 sigval val = { 1 };
229 pthread_sigqueue( alarm_thread, SIGALRM, val );
230 pthread_join( alarm_thread, NULL );
231 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopped\n");
232}
233
234void ?{}( preemption_scope * this, processor * proc ) {
235 (&this->alarm){ proc };
236 this->proc = proc;
237 this->proc->preemption_alarm = &this->alarm;
238 update_preemption( this->proc, this->proc->preemption );
239}
240
241void ^?{}( preemption_scope * this ) {
242 disable_interrupts();
243
244 update_preemption( this->proc, 0 );
245}
246
247//=============================================================================================
248// Kernel Signal Handlers
249//=============================================================================================
250
251void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) {
252 LIB_DEBUG_DO( last_interrupt = (void *)(cxt->uc_mcontext.gregs[CFA_REG_IP]); )
253 if( preemption_ready() ) {
254 preemption_in_progress = true;
255 signal_unblock( SIGUSR1 );
256 this_processor->pending_preemption = false;
257 preemption_in_progress = false;
258 BlockInternal( (thread_desc*)this_thread );
259 }
260 else {
261 defer_ctxSwitch();
262 }
263}
264
265void * alarm_loop( __attribute__((unused)) void * args ) {
266 sigset_t mask;
267 sigemptyset( &mask );
268 sigaddset( &mask, SIGALRM );
269
270 if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) {
271 abortf( "internal error, pthread_sigmask" );
272 }
273
274 while( true ) {
275 siginfo_t info;
276 int sig = sigwaitinfo( &mask, &info );
277 assertf(sig == SIGALRM, "Kernel Internal Error, sigwait: Unexpected signal %d (%d : %d)\n", sig, info.si_code, info.si_value.sival_int);
278
279 LIB_DEBUG_PRINT_SAFE("Kernel : Caught alarm from %d with %d\n", info.si_code, info.si_value.sival_int );
280 switch( info.si_code )
281 {
282 case SI_TIMER:
283 case SI_KERNEL:
284 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread tick\n");
285 lock( &systemProcessor->alarm_lock DEBUG_CTX2 );
286 tick_preemption();
287 unlock( &systemProcessor->alarm_lock );
288 break;
289 case SI_QUEUE:
290 goto EXIT;
291 }
292 }
293
294EXIT:
295 LIB_DEBUG_PRINT_SAFE("Kernel : Preemption thread stopping\n");
296 return NULL;
297}
298
299static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags ) {
300 struct sigaction act;
301
302 act.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
303 act.sa_flags = flags;
304
305 if ( sigaction( sig, &act, NULL ) == -1 ) {
306 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
307 " __kernel_sigaction( sig:%d, handler:%p, flags:%d ), problem installing signal handler, error(%d) %s.\n",
308 sig, handler, flags, errno, strerror( errno )
309 );
310 _exit( EXIT_FAILURE );
311 }
312}
313
314typedef void (*sa_handler_t)(int);
315
316static void __kernel_sigdefault( int sig ) {
317 struct sigaction act;
318
319 // act.sa_handler = SIG_DFL;
320 act.sa_flags = 0;
321 sigemptyset( &act.sa_mask );
322
323 if ( sigaction( sig, &act, NULL ) == -1 ) {
324 LIB_DEBUG_PRINT_BUFFER_DECL( STDERR_FILENO,
325 " __kernel_sigdefault( sig:%d ), problem reseting signal handler, error(%d) %s.\n",
326 sig, errno, strerror( errno )
327 );
328 _exit( EXIT_FAILURE );
329 }
330}
331
332//=============================================================================================
333// Terminating Signals logic
334//=============================================================================================
335
336LIB_DEBUG_DO(
337 static void __kernel_backtrace( int start ) {
338 // skip first N stack frames
339
340 enum { Frames = 50 };
341 void * array[Frames];
342 int size = backtrace( array, Frames );
343 char ** messages = backtrace_symbols( array, size );
344
345 // find executable name
346 *index( messages[0], '(' ) = '\0';
347 #ifdef __USE_STREAM__
348 serr | "Stack back trace for:" | messages[0] | endl;
349 #else
350 fprintf( stderr, "Stack back trace for: %s\n", messages[0]);
351 #endif
352
353 // skip last 2 stack frames after main
354 for ( int i = start; i < size && messages != NULL; i += 1 ) {
355 char * name = NULL;
356 char * offset_begin = NULL;
357 char * offset_end = NULL;
358
359 for ( char *p = messages[i]; *p; ++p ) {
360 // find parantheses and +offset
361 if ( *p == '(' ) {
362 name = p;
363 }
364 else if ( *p == '+' ) {
365 offset_begin = p;
366 }
367 else if ( *p == ')' ) {
368 offset_end = p;
369 break;
370 }
371 }
372
373 // if line contains symbol print it
374 int frameNo = i - start;
375 if ( name && offset_begin && offset_end && name < offset_begin ) {
376 // delimit strings
377 *name++ = '\0';
378 *offset_begin++ = '\0';
379 *offset_end++ = '\0';
380
381 #ifdef __USE_STREAM__
382 serr | "(" | frameNo | ")" | messages[i] | ":"
383 | name | "+" | offset_begin | offset_end | endl;
384 #else
385 fprintf( stderr, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
386 #endif
387 }
388 // otherwise, print the whole line
389 else {
390 #ifdef __USE_STREAM__
391 serr | "(" | frameNo | ")" | messages[i] | endl;
392 #else
393 fprintf( stderr, "(%i) %s\n", frameNo, messages[i] );
394 #endif
395 }
396 }
397
398 free( messages );
399 }
400)
401
402// void sigHandler_segv( __CFA_SIGPARMS__ ) {
403// LIB_DEBUG_DO(
404// #ifdef __USE_STREAM__
405// serr | "*CFA runtime error* program cfa-cpp terminated with"
406// | (sig == SIGSEGV ? "segment fault." : "bus error.")
407// | endl;
408// #else
409// fprintf( stderr, "*CFA runtime error* program cfa-cpp terminated with %s\n", sig == SIGSEGV ? "segment fault." : "bus error." );
410// #endif
411
412// // skip first 2 stack frames
413// __kernel_backtrace( 1 );
414// )
415// exit( EXIT_FAILURE );
416// }
417
418// void sigHandler_abort( __CFA_SIGPARMS__ ) {
419// // skip first 6 stack frames
420// LIB_DEBUG_DO( __kernel_backtrace( 6 ); )
421
422// // reset default signal handler
423// __kernel_sigdefault( SIGABRT );
424
425// raise( SIGABRT );
426// }
Note: See TracBrowser for help on using the repository browser.