[c81ebf9] | 1 | // |
---|
| 2 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
---|
| 3 | // |
---|
| 4 | // The contents of this file are covered under the licence agreement in the |
---|
| 5 | // file "LICENCE" distributed with Cforall. |
---|
| 6 | // |
---|
| 7 | // signal.c -- |
---|
| 8 | // |
---|
| 9 | // Author : Thierry Delisle |
---|
| 10 | // Created On : Mon Jun 5 14:20:42 2017 |
---|
[6b0b624] | 11 | // Last Modified By : Peter A. Buhr |
---|
[09d4b22] | 12 | // Last Modified On : Thu Dec 5 16:34:05 2019 |
---|
| 13 | // Update Count : 43 |
---|
[c81ebf9] | 14 | // |
---|
| 15 | |
---|
[2026bb6] | 16 | #define __cforall_thread__ |
---|
| 17 | |
---|
[73abe95] | 18 | #include "preemption.hfa" |
---|
[a83ffa4] | 19 | #include <assert.h> |
---|
[c81ebf9] | 20 | |
---|
| 21 | extern "C" { |
---|
[82ff5845] | 22 | #include <errno.h> |
---|
| 23 | #include <stdio.h> |
---|
| 24 | #include <string.h> |
---|
| 25 | #include <unistd.h> |
---|
[27f5f71] | 26 | #include <limits.h> // PTHREAD_STACK_MIN |
---|
[c81ebf9] | 27 | } |
---|
| 28 | |
---|
[73abe95] | 29 | #include "bits/signal.hfa" |
---|
[82ff5845] | 30 | |
---|
[d8548e2] | 31 | #if !defined(__CFA_DEFAULT_PREEMPTION__) |
---|
[2a84d06d] | 32 | #define __CFA_DEFAULT_PREEMPTION__ 10`ms |
---|
[d8548e2] | 33 | #endif |
---|
[c81ebf9] | 34 | |
---|
[2a84d06d] | 35 | Duration default_preemption() __attribute__((weak)) { |
---|
[c81ebf9] | 36 | return __CFA_DEFAULT_PREEMPTION__; |
---|
| 37 | } |
---|
| 38 | |
---|
[969b3fe] | 39 | // FwdDeclarations : timeout handlers |
---|
[c81ebf9] | 40 | static void preempt( processor * this ); |
---|
| 41 | static void timeout( thread_desc * this ); |
---|
| 42 | |
---|
[969b3fe] | 43 | // FwdDeclarations : Signal handlers |
---|
[c29c342] | 44 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ); |
---|
| 45 | static void sigHandler_segv ( __CFA_SIGPARMS__ ); |
---|
| 46 | static void sigHandler_ill ( __CFA_SIGPARMS__ ); |
---|
| 47 | static void sigHandler_fpe ( __CFA_SIGPARMS__ ); |
---|
| 48 | static void sigHandler_abort ( __CFA_SIGPARMS__ ); |
---|
[82ff5845] | 49 | |
---|
[969b3fe] | 50 | // FwdDeclarations : alarm thread main |
---|
[c29c342] | 51 | static void * alarm_loop( __attribute__((unused)) void * args ); |
---|
[969b3fe] | 52 | |
---|
| 53 | // Machine specific register name |
---|
[381fdee] | 54 | #if defined( __i386 ) |
---|
[b2b44d8] | 55 | #define CFA_REG_IP gregs[REG_EIP] |
---|
[381fdee] | 56 | #elif defined( __x86_64 ) |
---|
| 57 | #define CFA_REG_IP gregs[REG_RIP] |
---|
| 58 | #elif defined( __ARM_ARCH ) |
---|
[b2b44d8] | 59 | #define CFA_REG_IP arm_pc |
---|
[381fdee] | 60 | #else |
---|
| 61 | #error unknown hardware architecture |
---|
[cd17862] | 62 | #endif |
---|
| 63 | |
---|
[969b3fe] | 64 | KERNEL_STORAGE(event_kernel_t, event_kernel); // private storage for event kernel |
---|
| 65 | event_kernel_t * event_kernel; // kernel public handle to even kernel |
---|
| 66 | static pthread_t alarm_thread; // pthread handle to alarm thread |
---|
[09d4b22] | 67 | static void * alarm_stack; // pthread stack for alarm thread |
---|
[969b3fe] | 68 | |
---|
[c29c342] | 69 | static void ?{}(event_kernel_t & this) with( this ) { |
---|
[65deb18] | 70 | alarms{}; |
---|
| 71 | lock{}; |
---|
[969b3fe] | 72 | } |
---|
[82ff5845] | 73 | |
---|
[4dad189] | 74 | enum { |
---|
| 75 | PREEMPT_NORMAL = 0, |
---|
| 76 | PREEMPT_TERMINATE = 1, |
---|
| 77 | }; |
---|
| 78 | |
---|
[c81ebf9] | 79 | //============================================================================================= |
---|
| 80 | // Kernel Preemption logic |
---|
| 81 | //============================================================================================= |
---|
| 82 | |
---|
[969b3fe] | 83 | // Get next expired node |
---|
[2a84d06d] | 84 | static inline alarm_node_t * get_expired( alarm_list_t * alarms, Time currtime ) { |
---|
[27f5f71] | 85 | if( !alarms->head ) return 0p; // If no alarms return null |
---|
| 86 | if( alarms->head->alarm >= currtime ) return 0p; // If alarms head not expired return null |
---|
| 87 | return pop(alarms); // Otherwise just pop head |
---|
[969b3fe] | 88 | } |
---|
| 89 | |
---|
| 90 | // Tick one frame of the Discrete Event Simulation for alarms |
---|
[c29c342] | 91 | static void tick_preemption() { |
---|
[27f5f71] | 92 | alarm_node_t * node = 0p; // Used in the while loop but cannot be declared in the while condition |
---|
| 93 | alarm_list_t * alarms = &event_kernel->alarms; // Local copy for ease of reading |
---|
| 94 | Time currtime = __kernel_get_time(); // Check current time once so everything "happens at once" |
---|
[8cb529e] | 95 | |
---|
[969b3fe] | 96 | //Loop throught every thing expired |
---|
| 97 | while( node = get_expired( alarms, currtime ) ) { |
---|
[b1a4300] | 98 | // __cfaabi_dbg_print_buffer_decl( " KERNEL: preemption tick.\n" ); |
---|
[1c273d0] | 99 | |
---|
[969b3fe] | 100 | // Check if this is a kernel |
---|
[c81ebf9] | 101 | if( node->kernel_alarm ) { |
---|
| 102 | preempt( node->proc ); |
---|
| 103 | } |
---|
| 104 | else { |
---|
| 105 | timeout( node->thrd ); |
---|
| 106 | } |
---|
| 107 | |
---|
[969b3fe] | 108 | // Check if this is a periodic alarm |
---|
[2a84d06d] | 109 | Duration period = node->period; |
---|
[8cb529e] | 110 | if( period > 0 ) { |
---|
[b1a4300] | 111 | // __cfaabi_dbg_print_buffer_local( " KERNEL: alarm period is %lu.\n", period.tv ); |
---|
[969b3fe] | 112 | node->alarm = currtime + period; // Alarm is periodic, add currtime to it (used cached current time) |
---|
| 113 | insert( alarms, node ); // Reinsert the node for the next time it triggers |
---|
[c81ebf9] | 114 | } |
---|
| 115 | else { |
---|
[969b3fe] | 116 | node->set = false; // Node is one-shot, just mark it as not pending |
---|
[c81ebf9] | 117 | } |
---|
| 118 | } |
---|
| 119 | |
---|
[969b3fe] | 120 | // If there are still alarms pending, reset the timer |
---|
[b1a4300] | 121 | if( alarms->head ) { |
---|
[f083335] | 122 | __cfaabi_dbg_print_buffer_decl( " KERNEL: @%ju(%ju) resetting alarm to %ju.\n", currtime.tv, __kernel_get_time().tv, (alarms->head->alarm - currtime).tv); |
---|
[b1a4300] | 123 | Duration delta = alarms->head->alarm - currtime; |
---|
| 124 | Duration caped = max(delta, 50`us); |
---|
| 125 | // itimerval tim = { caped }; |
---|
| 126 | // __cfaabi_dbg_print_buffer_local( " Values are %lu, %lu, %lu %lu.\n", delta.tv, caped.tv, tim.it_value.tv_sec, tim.it_value.tv_usec); |
---|
| 127 | |
---|
| 128 | __kernel_set_timer( caped ); |
---|
| 129 | } |
---|
[c81ebf9] | 130 | } |
---|
| 131 | |
---|
[969b3fe] | 132 | // Update the preemption of a processor and notify interested parties |
---|
[2a84d06d] | 133 | void update_preemption( processor * this, Duration duration ) { |
---|
[c81ebf9] | 134 | alarm_node_t * alarm = this->preemption_alarm; |
---|
| 135 | |
---|
| 136 | // Alarms need to be enabled |
---|
[2a84d06d] | 137 | if ( duration > 0 && ! alarm->set ) { |
---|
[c81ebf9] | 138 | alarm->alarm = __kernel_get_time() + duration; |
---|
| 139 | alarm->period = duration; |
---|
| 140 | register_self( alarm ); |
---|
| 141 | } |
---|
[8ad6533] | 142 | // Zero duration but alarm is set |
---|
[c81ebf9] | 143 | else if ( duration == 0 && alarm->set ) { |
---|
| 144 | unregister_self( alarm ); |
---|
| 145 | alarm->alarm = 0; |
---|
| 146 | alarm->period = 0; |
---|
| 147 | } |
---|
| 148 | // If alarm is different from previous, change it |
---|
| 149 | else if ( duration > 0 && alarm->period != duration ) { |
---|
| 150 | unregister_self( alarm ); |
---|
| 151 | alarm->alarm = __kernel_get_time() + duration; |
---|
| 152 | alarm->period = duration; |
---|
| 153 | register_self( alarm ); |
---|
| 154 | } |
---|
| 155 | } |
---|
| 156 | |
---|
| 157 | //============================================================================================= |
---|
[cd17862] | 158 | // Kernel Signal Tools |
---|
[c81ebf9] | 159 | //============================================================================================= |
---|
| 160 | |
---|
[36982fc] | 161 | __cfaabi_dbg_debug_do( static thread_local void * last_interrupt = 0; ) |
---|
[b227f68] | 162 | |
---|
[82ff5845] | 163 | extern "C" { |
---|
[969b3fe] | 164 | // Disable interrupts by incrementing the counter |
---|
[82ff5845] | 165 | void disable_interrupts() { |
---|
[afd550c] | 166 | with( kernelTLS.preemption_state ) { |
---|
[1f81d61] | 167 | #if GCC_VERSION > 50000 |
---|
[13073be] | 168 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
---|
[1f81d61] | 169 | #endif |
---|
[13073be] | 170 | |
---|
| 171 | // Set enabled flag to false |
---|
| 172 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 173 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
| 174 | __atomic_store_n(&enabled, false, __ATOMIC_RELAXED); |
---|
| 175 | |
---|
| 176 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 177 | __atomic_signal_fence(__ATOMIC_ACQUIRE); |
---|
| 178 | |
---|
[de6319f] | 179 | __attribute__((unused)) unsigned short new_val = disable_count + 1; |
---|
| 180 | disable_count = new_val; |
---|
| 181 | verify( new_val < 65_000u ); // If this triggers someone is disabling interrupts without enabling them |
---|
| 182 | } |
---|
[82ff5845] | 183 | } |
---|
| 184 | |
---|
[969b3fe] | 185 | // Enable interrupts by decrementing the counter |
---|
| 186 | // If counter reaches 0, execute any pending CtxSwitch |
---|
[36982fc] | 187 | void enable_interrupts( __cfaabi_dbg_ctx_param ) { |
---|
[13073be] | 188 | processor * proc = kernelTLS.this_processor; // Cache the processor now since interrupts can start happening after the atomic store |
---|
| 189 | thread_desc * thrd = kernelTLS.this_thread; // Cache the thread now since interrupts can start happening after the atomic store |
---|
[969b3fe] | 190 | |
---|
[afd550c] | 191 | with( kernelTLS.preemption_state ){ |
---|
[de6319f] | 192 | unsigned short prev = disable_count; |
---|
| 193 | disable_count -= 1; |
---|
| 194 | verify( prev != 0u ); // If this triggers someone is enabled already enabled interruptsverify( prev != 0u ); |
---|
| 195 | |
---|
| 196 | // Check if we need to prempt the thread because an interrupt was missed |
---|
| 197 | if( prev == 1 ) { |
---|
[1f81d61] | 198 | #if GCC_VERSION > 50000 |
---|
[13073be] | 199 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
---|
[1f81d61] | 200 | #endif |
---|
[13073be] | 201 | |
---|
| 202 | // Set enabled flag to true |
---|
| 203 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 204 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
| 205 | __atomic_store_n(&enabled, true, __ATOMIC_RELAXED); |
---|
| 206 | |
---|
| 207 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 208 | __atomic_signal_fence(__ATOMIC_RELEASE); |
---|
[de6319f] | 209 | if( proc->pending_preemption ) { |
---|
| 210 | proc->pending_preemption = false; |
---|
| 211 | BlockInternal( thrd ); |
---|
| 212 | } |
---|
[d0a045c7] | 213 | } |
---|
[82ff5845] | 214 | } |
---|
[4e6fb8e] | 215 | |
---|
[969b3fe] | 216 | // For debugging purposes : keep track of the last person to enable the interrupts |
---|
[36982fc] | 217 | __cfaabi_dbg_debug_do( proc->last_enable = caller; ) |
---|
[82ff5845] | 218 | } |
---|
[969b3fe] | 219 | |
---|
| 220 | // Disable interrupts by incrementint the counter |
---|
| 221 | // Don't execute any pending CtxSwitch even if counter reaches 0 |
---|
| 222 | void enable_interrupts_noPoll() { |
---|
[afd550c] | 223 | unsigned short prev = kernelTLS.preemption_state.disable_count; |
---|
| 224 | kernelTLS.preemption_state.disable_count -= 1; |
---|
[2e9aed4] | 225 | verifyf( prev != 0u, "Incremented from %u\n", prev ); // If this triggers someone is enabled already enabled interrupts |
---|
[d0a045c7] | 226 | if( prev == 1 ) { |
---|
[1f81d61] | 227 | #if GCC_VERSION > 50000 |
---|
[13073be] | 228 | static_assert(__atomic_always_lock_free(sizeof(kernelTLS.preemption_state.enabled), &kernelTLS.preemption_state.enabled), "Must be lock-free"); |
---|
[1f81d61] | 229 | #endif |
---|
[13073be] | 230 | // Set enabled flag to true |
---|
| 231 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 232 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
| 233 | __atomic_store_n(&kernelTLS.preemption_state.enabled, true, __ATOMIC_RELAXED); |
---|
| 234 | |
---|
| 235 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 236 | __atomic_signal_fence(__ATOMIC_RELEASE); |
---|
[d0a045c7] | 237 | } |
---|
[969b3fe] | 238 | } |
---|
[82ff5845] | 239 | } |
---|
| 240 | |
---|
[969b3fe] | 241 | // sigprocmask wrapper : unblock a single signal |
---|
[1c273d0] | 242 | static inline void signal_unblock( int sig ) { |
---|
[82ff5845] | 243 | sigset_t mask; |
---|
| 244 | sigemptyset( &mask ); |
---|
[1c273d0] | 245 | sigaddset( &mask, sig ); |
---|
[82ff5845] | 246 | |
---|
[27f5f71] | 247 | if ( pthread_sigmask( SIG_UNBLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 248 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 249 | } |
---|
[82ff5845] | 250 | } |
---|
| 251 | |
---|
[969b3fe] | 252 | // sigprocmask wrapper : block a single signal |
---|
[cd17862] | 253 | static inline void signal_block( int sig ) { |
---|
| 254 | sigset_t mask; |
---|
| 255 | sigemptyset( &mask ); |
---|
| 256 | sigaddset( &mask, sig ); |
---|
[47ecf2b] | 257 | |
---|
[27f5f71] | 258 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 259 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 260 | } |
---|
| 261 | } |
---|
[47ecf2b] | 262 | |
---|
[969b3fe] | 263 | // kill wrapper : signal a processor |
---|
[cd17862] | 264 | static void preempt( processor * this ) { |
---|
[4dad189] | 265 | sigval_t value = { PREEMPT_NORMAL }; |
---|
| 266 | pthread_sigqueue( this->kernel_thread, SIGUSR1, value ); |
---|
| 267 | } |
---|
| 268 | |
---|
[969b3fe] | 269 | // reserved for future use |
---|
[cd17862] | 270 | static void timeout( thread_desc * this ) { |
---|
| 271 | //TODO : implement waking threads |
---|
| 272 | } |
---|
| 273 | |
---|
[14a61b5] | 274 | // KERNEL ONLY |
---|
[969b3fe] | 275 | // Check if a CtxSwitch signal handler shoud defer |
---|
| 276 | // If true : preemption is safe |
---|
| 277 | // If false : preemption is unsafe and marked as pending |
---|
| 278 | static inline bool preemption_ready() { |
---|
[14a61b5] | 279 | // Check if preemption is safe |
---|
| 280 | bool ready = kernelTLS.preemption_state.enabled && ! kernelTLS.preemption_state.in_progress; |
---|
| 281 | |
---|
| 282 | // Adjust the pending flag accordingly |
---|
| 283 | kernelTLS.this_processor->pending_preemption = !ready; |
---|
[969b3fe] | 284 | return ready; |
---|
| 285 | } |
---|
| 286 | |
---|
[cd17862] | 287 | //============================================================================================= |
---|
| 288 | // Kernel Signal Startup/Shutdown logic |
---|
| 289 | //============================================================================================= |
---|
| 290 | |
---|
[969b3fe] | 291 | // Startup routine to activate preemption |
---|
| 292 | // Called from kernel_startup |
---|
[cd17862] | 293 | void kernel_start_preemption() { |
---|
[169d944] | 294 | __cfaabi_dbg_print_safe( "Kernel : Starting preemption\n" ); |
---|
[969b3fe] | 295 | |
---|
| 296 | // Start with preemption disabled until ready |
---|
[14a61b5] | 297 | kernelTLS.preemption_state.enabled = false; |
---|
| 298 | kernelTLS.preemption_state.disable_count = 1; |
---|
[969b3fe] | 299 | |
---|
| 300 | // Initialize the event kernel |
---|
| 301 | event_kernel = (event_kernel_t *)&storage_event_kernel; |
---|
[9236060] | 302 | (*event_kernel){}; |
---|
[969b3fe] | 303 | |
---|
| 304 | // Setup proper signal handlers |
---|
[27f5f71] | 305 | __cfaabi_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO | SA_RESTART ); // CtxSwitch handler |
---|
[cd17862] | 306 | |
---|
| 307 | signal_block( SIGALRM ); |
---|
| 308 | |
---|
[09d4b22] | 309 | alarm_stack = create_pthread( &alarm_thread, alarm_loop, 0p ); |
---|
[cd17862] | 310 | } |
---|
| 311 | |
---|
[969b3fe] | 312 | // Shutdown routine to deactivate preemption |
---|
| 313 | // Called from kernel_shutdown |
---|
[cd17862] | 314 | void kernel_stop_preemption() { |
---|
[169d944] | 315 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopping\n" ); |
---|
[d6ff3ff] | 316 | |
---|
[969b3fe] | 317 | // Block all signals since we are already shutting down |
---|
[cd17862] | 318 | sigset_t mask; |
---|
| 319 | sigfillset( &mask ); |
---|
[27f5f71] | 320 | sigprocmask( SIG_BLOCK, &mask, 0p ); |
---|
[cd17862] | 321 | |
---|
[969b3fe] | 322 | // Notify the alarm thread of the shutdown |
---|
[a0b3e32] | 323 | sigval val = { 1 }; |
---|
| 324 | pthread_sigqueue( alarm_thread, SIGALRM, val ); |
---|
[969b3fe] | 325 | |
---|
| 326 | // Wait for the preemption thread to finish |
---|
[27f5f71] | 327 | |
---|
| 328 | pthread_join( alarm_thread, 0p ); |
---|
[09d4b22] | 329 | free( alarm_stack ); |
---|
[969b3fe] | 330 | |
---|
| 331 | // Preemption is now fully stopped |
---|
| 332 | |
---|
[169d944] | 333 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopped\n" ); |
---|
[cd17862] | 334 | } |
---|
| 335 | |
---|
[969b3fe] | 336 | // Raii ctor/dtor for the preemption_scope |
---|
| 337 | // Used by thread to control when they want to receive preemption signals |
---|
[242a902] | 338 | void ?{}( preemption_scope & this, processor * proc ) { |
---|
[2a84d06d] | 339 | (this.alarm){ proc, (Time){ 0 }, 0`s }; |
---|
[242a902] | 340 | this.proc = proc; |
---|
| 341 | this.proc->preemption_alarm = &this.alarm; |
---|
[969b3fe] | 342 | |
---|
[d8548e2] | 343 | update_preemption( this.proc, this.proc->cltr->preemption_rate ); |
---|
[cd17862] | 344 | } |
---|
| 345 | |
---|
[242a902] | 346 | void ^?{}( preemption_scope & this ) { |
---|
[cd17862] | 347 | disable_interrupts(); |
---|
| 348 | |
---|
[2a84d06d] | 349 | update_preemption( this.proc, 0`s ); |
---|
[cd17862] | 350 | } |
---|
| 351 | |
---|
| 352 | //============================================================================================= |
---|
| 353 | // Kernel Signal Handlers |
---|
| 354 | //============================================================================================= |
---|
[47ecf2b] | 355 | |
---|
[969b3fe] | 356 | // Context switch signal handler |
---|
| 357 | // Receives SIGUSR1 signal and causes the current thread to yield |
---|
[c29c342] | 358 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) { |
---|
[b2b44d8] | 359 | __cfaabi_dbg_debug_do( last_interrupt = (void *)(cxt->uc_mcontext.CFA_REG_IP); ) |
---|
[969b3fe] | 360 | |
---|
[4dad189] | 361 | // SKULLDUGGERY: if a thread creates a processor and the immediately deletes it, |
---|
| 362 | // the interrupt that is supposed to force the kernel thread to preempt might arrive |
---|
| 363 | // before the kernel thread has even started running. When that happens an iterrupt |
---|
| 364 | // we a null 'this_processor' will be caught, just ignore it. |
---|
[14a61b5] | 365 | if(! kernelTLS.this_processor ) return; |
---|
[4dad189] | 366 | |
---|
| 367 | choose(sfp->si_value.sival_int) { |
---|
| 368 | case PREEMPT_NORMAL : ;// Normal case, nothing to do here |
---|
[ea8b2f7] | 369 | case PREEMPT_TERMINATE: verify( __atomic_load_n( &kernelTLS.this_processor->do_terminate, __ATOMIC_SEQ_CST ) ); |
---|
[4dad189] | 370 | default: |
---|
[ff878b7] | 371 | abort( "internal error, signal value is %d", sfp->si_value.sival_int ); |
---|
[4dad189] | 372 | } |
---|
| 373 | |
---|
[b2b44d8] | 374 | // Check if it is safe to preempt here |
---|
[969b3fe] | 375 | if( !preemption_ready() ) { return; } |
---|
| 376 | |
---|
[b1a4300] | 377 | __cfaabi_dbg_print_buffer_decl( " KERNEL: preempting core %p (%p @ %p).\n", kernelTLS.this_processor, kernelTLS.this_thread, (void *)(cxt->uc_mcontext.CFA_REG_IP) ); |
---|
[14a61b5] | 378 | |
---|
| 379 | // Sync flag : prevent recursive calls to the signal handler |
---|
| 380 | kernelTLS.preemption_state.in_progress = true; |
---|
| 381 | |
---|
[a83ffa4] | 382 | // Clear sighandler mask before context switching. |
---|
[1f81d61] | 383 | #if GCC_VERSION > 50000 |
---|
[a83ffa4] | 384 | static_assert( sizeof( sigset_t ) == sizeof( cxt->uc_sigmask ), "Expected cxt->uc_sigmask to be of sigset_t" ); |
---|
[1f81d61] | 385 | #endif |
---|
[27f5f71] | 386 | if ( pthread_sigmask( SIG_SETMASK, (sigset_t *)&(cxt->uc_sigmask), 0p ) == -1 ) { |
---|
[a83ffa4] | 387 | abort( "internal error, sigprocmask" ); |
---|
| 388 | } |
---|
[05615ba] | 389 | |
---|
[14a61b5] | 390 | // TODO: this should go in finish action |
---|
| 391 | // Clear the in progress flag |
---|
| 392 | kernelTLS.preemption_state.in_progress = false; |
---|
[969b3fe] | 393 | |
---|
| 394 | // Preemption can occur here |
---|
| 395 | |
---|
[14a61b5] | 396 | BlockInternal( kernelTLS.this_thread ); // Do the actual CtxSwitch |
---|
[c81ebf9] | 397 | } |
---|
| 398 | |
---|
[969b3fe] | 399 | // Main of the alarm thread |
---|
| 400 | // Waits on SIGALRM and send SIGUSR1 to whom ever needs it |
---|
[c29c342] | 401 | static void * alarm_loop( __attribute__((unused)) void * args ) { |
---|
[969b3fe] | 402 | // Block sigalrms to control when they arrive |
---|
[cd17862] | 403 | sigset_t mask; |
---|
[ade5272] | 404 | sigfillset(&mask); |
---|
[27f5f71] | 405 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 406 | abort( "internal error, pthread_sigmask" ); |
---|
[82ff5845] | 407 | } |
---|
[c81ebf9] | 408 | |
---|
[ade5272] | 409 | sigemptyset( &mask ); |
---|
| 410 | sigaddset( &mask, SIGALRM ); |
---|
| 411 | |
---|
[969b3fe] | 412 | // Main loop |
---|
[cd17862] | 413 | while( true ) { |
---|
[969b3fe] | 414 | // Wait for a sigalrm |
---|
[a0b3e32] | 415 | siginfo_t info; |
---|
| 416 | int sig = sigwaitinfo( &mask, &info ); |
---|
[969b3fe] | 417 | |
---|
[e2f7bc3] | 418 | if( sig < 0 ) { |
---|
| 419 | //Error! |
---|
| 420 | int err = errno; |
---|
| 421 | switch( err ) { |
---|
| 422 | case EAGAIN : |
---|
| 423 | case EINTR : |
---|
[b1a4300] | 424 | {__cfaabi_dbg_print_buffer_decl( " KERNEL: Spurious wakeup %d.\n", err );} |
---|
[e2f7bc3] | 425 | continue; |
---|
[27f5f71] | 426 | case EINVAL : |
---|
[169d944] | 427 | abort( "Timeout was invalid." ); |
---|
[e2f7bc3] | 428 | default: |
---|
[169d944] | 429 | abort( "Unhandled error %d", err); |
---|
[e2f7bc3] | 430 | } |
---|
| 431 | } |
---|
| 432 | |
---|
[969b3fe] | 433 | // If another signal arrived something went wrong |
---|
[8cb529e] | 434 | assertf(sig == SIGALRM, "Kernel Internal Error, sigwait: Unexpected signal %d (%d : %d)\n", sig, info.si_code, info.si_value.sival_int); |
---|
| 435 | |
---|
[169d944] | 436 | // __cfaabi_dbg_print_safe( "Kernel : Caught alarm from %d with %d\n", info.si_code, info.si_value.sival_int ); |
---|
[969b3fe] | 437 | // Switch on the code (a.k.a. the sender) to |
---|
[8cb529e] | 438 | switch( info.si_code ) |
---|
[a0b3e32] | 439 | { |
---|
[969b3fe] | 440 | // Timers can apparently be marked as sent for the kernel |
---|
| 441 | // In either case, tick preemption |
---|
[8cb529e] | 442 | case SI_TIMER: |
---|
| 443 | case SI_KERNEL: |
---|
[169d944] | 444 | // __cfaabi_dbg_print_safe( "Kernel : Preemption thread tick\n" ); |
---|
[36982fc] | 445 | lock( event_kernel->lock __cfaabi_dbg_ctx2 ); |
---|
[8cb529e] | 446 | tick_preemption(); |
---|
[ea7d2b0] | 447 | unlock( event_kernel->lock ); |
---|
[8cb529e] | 448 | break; |
---|
[969b3fe] | 449 | // Signal was not sent by the kernel but by an other thread |
---|
[8cb529e] | 450 | case SI_QUEUE: |
---|
[969b3fe] | 451 | // For now, other thread only signal the alarm thread to shut it down |
---|
| 452 | // If this needs to change use info.si_value and handle the case here |
---|
[8cb529e] | 453 | goto EXIT; |
---|
[cd17862] | 454 | } |
---|
| 455 | } |
---|
[a0b3e32] | 456 | |
---|
[8cb529e] | 457 | EXIT: |
---|
[169d944] | 458 | __cfaabi_dbg_print_safe( "Kernel : Preemption thread stopping\n" ); |
---|
[27f5f71] | 459 | return 0p; |
---|
[82ff5845] | 460 | } |
---|
| 461 | |
---|
[b68fc85] | 462 | //============================================================================================= |
---|
| 463 | // Kernel Signal Debug |
---|
| 464 | //============================================================================================= |
---|
| 465 | |
---|
| 466 | void __cfaabi_check_preemption() { |
---|
[14a61b5] | 467 | bool ready = kernelTLS.preemption_state.enabled; |
---|
[b68fc85] | 468 | if(!ready) { abort("Preemption should be ready"); } |
---|
| 469 | |
---|
| 470 | sigset_t oldset; |
---|
| 471 | int ret; |
---|
[27f5f71] | 472 | ret = pthread_sigmask(0, 0p, &oldset); |
---|
[b68fc85] | 473 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
---|
| 474 | |
---|
| 475 | ret = sigismember(&oldset, SIGUSR1); |
---|
| 476 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 477 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
---|
[a83ffa4] | 478 | |
---|
| 479 | ret = sigismember(&oldset, SIGALRM); |
---|
| 480 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 481 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
---|
| 482 | |
---|
| 483 | ret = sigismember(&oldset, SIGTERM); |
---|
| 484 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 485 | if(ret == 1) { abort("ERROR SIGTERM is disabled"); } |
---|
[b68fc85] | 486 | } |
---|
| 487 | |
---|
[ea8b2f7] | 488 | #ifdef __CFA_WITH_VERIFY__ |
---|
| 489 | bool __cfaabi_dbg_in_kernel() { |
---|
| 490 | return !kernelTLS.preemption_state.enabled; |
---|
| 491 | } |
---|
| 492 | #endif |
---|
| 493 | |
---|
[6b0b624] | 494 | // Local Variables: // |
---|
| 495 | // mode: c // |
---|
| 496 | // tab-width: 4 // |
---|
| 497 | // End: // |
---|