[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 |
---|
[231b18f] | 12 | // Last Modified On : Fri Nov 6 07:42:13 2020 |
---|
| 13 | // Update Count : 54 |
---|
[c81ebf9] | 14 | // |
---|
| 15 | |
---|
[2026bb6] | 16 | #define __cforall_thread__ |
---|
[1c6e1ec] | 17 | // #define __CFA_DEBUG_PRINT_PREEMPTION__ |
---|
[2026bb6] | 18 | |
---|
[73abe95] | 19 | #include "preemption.hfa" |
---|
[a83ffa4] | 20 | #include <assert.h> |
---|
[c81ebf9] | 21 | |
---|
[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 | |
---|
[73abe95] | 28 | #include "bits/signal.hfa" |
---|
[e660761] | 29 | #include "kernel_private.hfa" |
---|
[82ff5845] | 30 | |
---|
[1c6e1ec] | 31 | |
---|
[d8548e2] | 32 | #if !defined(__CFA_DEFAULT_PREEMPTION__) |
---|
[2a84d06d] | 33 | #define __CFA_DEFAULT_PREEMPTION__ 10`ms |
---|
[d8548e2] | 34 | #endif |
---|
[c81ebf9] | 35 | |
---|
[1c6e1ec] | 36 | __attribute__((weak)) Duration default_preemption() { |
---|
[357fae8] | 37 | const char * preempt_rate_s = getenv("CFA_DEFAULT_PREEMPTION"); |
---|
[1c6e1ec] | 38 | if(!preempt_rate_s) { |
---|
[357fae8] | 39 | __cfadbg_print_safe(preemption, "No CFA_DEFAULT_PREEMPTION in ENV\n"); |
---|
[1c6e1ec] | 40 | return __CFA_DEFAULT_PREEMPTION__; |
---|
| 41 | } |
---|
| 42 | |
---|
| 43 | char * endptr = 0p; |
---|
| 44 | long int preempt_rate_l = strtol(preempt_rate_s, &endptr, 10); |
---|
| 45 | if(preempt_rate_l < 0 || preempt_rate_l > 65535) { |
---|
[357fae8] | 46 | __cfadbg_print_safe(preemption, "CFA_DEFAULT_PREEMPTION out of range : %ld\n", preempt_rate_l); |
---|
[1c6e1ec] | 47 | return __CFA_DEFAULT_PREEMPTION__; |
---|
| 48 | } |
---|
| 49 | if('\0' != *endptr) { |
---|
[357fae8] | 50 | __cfadbg_print_safe(preemption, "CFA_DEFAULT_PREEMPTION not a decimal number : %s\n", preempt_rate_s); |
---|
[1c6e1ec] | 51 | return __CFA_DEFAULT_PREEMPTION__; |
---|
| 52 | } |
---|
| 53 | |
---|
| 54 | return preempt_rate_l`ms; |
---|
[c81ebf9] | 55 | } |
---|
| 56 | |
---|
[969b3fe] | 57 | // FwdDeclarations : timeout handlers |
---|
[c81ebf9] | 58 | static void preempt( processor * this ); |
---|
[e873838] | 59 | static void timeout( $thread * this ); |
---|
[c81ebf9] | 60 | |
---|
[969b3fe] | 61 | // FwdDeclarations : Signal handlers |
---|
[c29c342] | 62 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ); |
---|
[c59a346] | 63 | static void sigHandler_alarm ( __CFA_SIGPARMS__ ); |
---|
[c29c342] | 64 | static void sigHandler_segv ( __CFA_SIGPARMS__ ); |
---|
| 65 | static void sigHandler_ill ( __CFA_SIGPARMS__ ); |
---|
| 66 | static void sigHandler_fpe ( __CFA_SIGPARMS__ ); |
---|
| 67 | static void sigHandler_abort ( __CFA_SIGPARMS__ ); |
---|
[82ff5845] | 68 | |
---|
[969b3fe] | 69 | // FwdDeclarations : alarm thread main |
---|
[c29c342] | 70 | static void * alarm_loop( __attribute__((unused)) void * args ); |
---|
[969b3fe] | 71 | |
---|
| 72 | // Machine specific register name |
---|
[381fdee] | 73 | #if defined( __i386 ) |
---|
[b2b44d8] | 74 | #define CFA_REG_IP gregs[REG_EIP] |
---|
[381fdee] | 75 | #elif defined( __x86_64 ) |
---|
| 76 | #define CFA_REG_IP gregs[REG_RIP] |
---|
[e9b49379] | 77 | #elif defined( __arm__ ) |
---|
| 78 | #define CFA_REG_IP arm_pc |
---|
| 79 | #elif defined( __aarch64__ ) |
---|
[482fa08] | 80 | #define CFA_REG_IP pc |
---|
[381fdee] | 81 | #else |
---|
[e9b49379] | 82 | #error unsupported hardware architecture |
---|
[cd17862] | 83 | #endif |
---|
| 84 | |
---|
[969b3fe] | 85 | KERNEL_STORAGE(event_kernel_t, event_kernel); // private storage for event kernel |
---|
| 86 | event_kernel_t * event_kernel; // kernel public handle to even kernel |
---|
| 87 | static pthread_t alarm_thread; // pthread handle to alarm thread |
---|
[09d4b22] | 88 | static void * alarm_stack; // pthread stack for alarm thread |
---|
[969b3fe] | 89 | |
---|
[c29c342] | 90 | static void ?{}(event_kernel_t & this) with( this ) { |
---|
[65deb18] | 91 | alarms{}; |
---|
| 92 | lock{}; |
---|
[969b3fe] | 93 | } |
---|
[82ff5845] | 94 | |
---|
[4dad189] | 95 | enum { |
---|
| 96 | PREEMPT_NORMAL = 0, |
---|
| 97 | PREEMPT_TERMINATE = 1, |
---|
| 98 | }; |
---|
| 99 | |
---|
[c81ebf9] | 100 | //============================================================================================= |
---|
| 101 | // Kernel Preemption logic |
---|
| 102 | //============================================================================================= |
---|
| 103 | |
---|
[969b3fe] | 104 | // Get next expired node |
---|
[2a84d06d] | 105 | static inline alarm_node_t * get_expired( alarm_list_t * alarms, Time currtime ) { |
---|
[d3ab183] | 106 | if( ! & (*alarms)`first ) return 0p; // If no alarms return null |
---|
| 107 | if( (*alarms)`first.alarm >= currtime ) return 0p; // If alarms head not expired return null |
---|
[27f5f71] | 108 | return pop(alarms); // Otherwise just pop head |
---|
[969b3fe] | 109 | } |
---|
| 110 | |
---|
| 111 | // Tick one frame of the Discrete Event Simulation for alarms |
---|
[e873838] | 112 | static void tick_preemption(void) { |
---|
[27f5f71] | 113 | alarm_node_t * node = 0p; // Used in the while loop but cannot be declared in the while condition |
---|
| 114 | alarm_list_t * alarms = &event_kernel->alarms; // Local copy for ease of reading |
---|
| 115 | Time currtime = __kernel_get_time(); // Check current time once so everything "happens at once" |
---|
[8cb529e] | 116 | |
---|
[969b3fe] | 117 | //Loop throught every thing expired |
---|
| 118 | while( node = get_expired( alarms, currtime ) ) { |
---|
[b1a4300] | 119 | // __cfaabi_dbg_print_buffer_decl( " KERNEL: preemption tick.\n" ); |
---|
[185efe6] | 120 | Duration period = node->period; |
---|
| 121 | if( period == 0) { |
---|
| 122 | node->set = false; // Node is one-shot, just mark it as not pending |
---|
| 123 | } |
---|
[1c273d0] | 124 | |
---|
[969b3fe] | 125 | // Check if this is a kernel |
---|
[4b30e8cc] | 126 | if( node->type == Kernel ) { |
---|
[c81ebf9] | 127 | preempt( node->proc ); |
---|
| 128 | } |
---|
[4b30e8cc] | 129 | else if( node->type == User ) { |
---|
[e873838] | 130 | timeout( node->thrd ); |
---|
[c81ebf9] | 131 | } |
---|
[4b30e8cc] | 132 | else { |
---|
[eeb5023] | 133 | node->callback(*node); |
---|
[4b30e8cc] | 134 | } |
---|
[c81ebf9] | 135 | |
---|
[969b3fe] | 136 | // Check if this is a periodic alarm |
---|
[8cb529e] | 137 | if( period > 0 ) { |
---|
[b1a4300] | 138 | // __cfaabi_dbg_print_buffer_local( " KERNEL: alarm period is %lu.\n", period.tv ); |
---|
[969b3fe] | 139 | node->alarm = currtime + period; // Alarm is periodic, add currtime to it (used cached current time) |
---|
| 140 | insert( alarms, node ); // Reinsert the node for the next time it triggers |
---|
[c81ebf9] | 141 | } |
---|
| 142 | } |
---|
| 143 | |
---|
[969b3fe] | 144 | // If there are still alarms pending, reset the timer |
---|
[d3ab183] | 145 | if( & (*alarms)`first ) { |
---|
| 146 | Duration delta = (*alarms)`first.alarm - currtime; |
---|
| 147 | Duration capped = max(delta, 50`us); |
---|
| 148 | __kernel_set_timer( capped ); |
---|
[b1a4300] | 149 | } |
---|
[c81ebf9] | 150 | } |
---|
| 151 | |
---|
[969b3fe] | 152 | // Update the preemption of a processor and notify interested parties |
---|
[2a84d06d] | 153 | void update_preemption( processor * this, Duration duration ) { |
---|
[c81ebf9] | 154 | alarm_node_t * alarm = this->preemption_alarm; |
---|
| 155 | |
---|
| 156 | // Alarms need to be enabled |
---|
[2a84d06d] | 157 | if ( duration > 0 && ! alarm->set ) { |
---|
[c81ebf9] | 158 | alarm->alarm = __kernel_get_time() + duration; |
---|
| 159 | alarm->period = duration; |
---|
| 160 | register_self( alarm ); |
---|
| 161 | } |
---|
[8ad6533] | 162 | // Zero duration but alarm is set |
---|
[c81ebf9] | 163 | else if ( duration == 0 && alarm->set ) { |
---|
| 164 | unregister_self( alarm ); |
---|
| 165 | alarm->alarm = 0; |
---|
| 166 | alarm->period = 0; |
---|
| 167 | } |
---|
| 168 | // If alarm is different from previous, change it |
---|
| 169 | else if ( duration > 0 && alarm->period != duration ) { |
---|
| 170 | unregister_self( alarm ); |
---|
| 171 | alarm->alarm = __kernel_get_time() + duration; |
---|
| 172 | alarm->period = duration; |
---|
| 173 | register_self( alarm ); |
---|
| 174 | } |
---|
| 175 | } |
---|
| 176 | |
---|
| 177 | //============================================================================================= |
---|
[cd17862] | 178 | // Kernel Signal Tools |
---|
[c81ebf9] | 179 | //============================================================================================= |
---|
[231b18f] | 180 | // In a user-level threading system, there are handful of thread-local variables where this problem occurs on the ARM. |
---|
[54dcab1] | 181 | // |
---|
[231b18f] | 182 | // For each kernel thread running user-level threads, there is a flag variable to indicate if interrupts are |
---|
| 183 | // enabled/disabled for that kernel thread. Therefore, this variable is made thread local. |
---|
[54dcab1] | 184 | // |
---|
[231b18f] | 185 | // For example, this code fragment sets the state of the "interrupt" variable in thread-local memory. |
---|
[54dcab1] | 186 | // |
---|
[231b18f] | 187 | // _Thread_local volatile int interrupts; |
---|
| 188 | // int main() { |
---|
| 189 | // interrupts = 0; // disable interrupts } |
---|
[54dcab1] | 190 | // |
---|
[231b18f] | 191 | // which generates the following code on the ARM |
---|
[54dcab1] | 192 | // |
---|
[231b18f] | 193 | // (gdb) disassemble main |
---|
| 194 | // Dump of assembler code for function main: |
---|
| 195 | // 0x0000000000000610 <+0>: mrs x1, tpidr_el0 |
---|
| 196 | // 0x0000000000000614 <+4>: mov w0, #0x0 // #0 |
---|
| 197 | // 0x0000000000000618 <+8>: add x1, x1, #0x0, lsl #12 |
---|
| 198 | // 0x000000000000061c <+12>: add x1, x1, #0x10 |
---|
| 199 | // 0x0000000000000620 <+16>: str wzr, [x1] |
---|
| 200 | // 0x0000000000000624 <+20>: ret |
---|
[54dcab1] | 201 | // |
---|
[231b18f] | 202 | // The mrs moves a pointer from coprocessor register tpidr_el0 into register x1. Register w0 is set to 0. The two adds |
---|
| 203 | // increase the TLS pointer with the displacement (offset) 0x10, which is the location in the TSL of variable |
---|
| 204 | // "interrupts". Finally, 0 is stored into "interrupts" through the pointer in register x1 that points into the |
---|
| 205 | // TSL. Now once x1 has the pointer to the location of the TSL for kernel thread N, it can be be preempted at a |
---|
| 206 | // user-level and the user thread is put on the user-level ready-queue. When the preempted thread gets to the front of |
---|
| 207 | // the user-level ready-queue it is run on kernel thread M. It now stores 0 into "interrupts" back on kernel thread N, |
---|
| 208 | // turning off interrupt on the wrong kernel thread. |
---|
[54dcab1] | 209 | // |
---|
[231b18f] | 210 | // On the x86, the following code is generated for the same code fragment. |
---|
[54dcab1] | 211 | // |
---|
[231b18f] | 212 | // (gdb) disassemble main |
---|
| 213 | // Dump of assembler code for function main: |
---|
| 214 | // 0x0000000000400420 <+0>: movl $0x0,%fs:0xfffffffffffffffc |
---|
| 215 | // 0x000000000040042c <+12>: xor %eax,%eax |
---|
[54dcab1] | 216 | // 0x000000000040042e <+14>: retq |
---|
| 217 | // |
---|
[231b18f] | 218 | // and there is base-displacement addressing used to atomically reset variable "interrupts" off of the TSL pointer in |
---|
| 219 | // register "fs". |
---|
[54dcab1] | 220 | // |
---|
[231b18f] | 221 | // Hence, the ARM has base-displacement address for the general purpose registers, BUT not to the coprocessor |
---|
| 222 | // registers. As a result, generating the address for the write into variable "interrupts" is no longer atomic. |
---|
[54dcab1] | 223 | // |
---|
[231b18f] | 224 | // Note this problem does NOT occur when just using multiple kernel threads because the preemption ALWAYS restarts the |
---|
| 225 | // thread on the same kernel thread. |
---|
[54dcab1] | 226 | // |
---|
[231b18f] | 227 | // The obvious question is why does ARM use a coprocessor register to store the TSL pointer given that coprocessor |
---|
| 228 | // registers are second-class registers with respect to the instruction set. One possible answer is that they did not |
---|
| 229 | // want to dedicate one of the general registers to hold the TLS pointer and there was a free coprocessor register |
---|
| 230 | // available. |
---|
[c81ebf9] | 231 | |
---|
[ead174a] | 232 | //----------------------------------------------------------------------------- |
---|
| 233 | // Some assembly required |
---|
| 234 | #define __cfaasm_label(label, when) when: asm volatile goto(".global __cfaasm_" #label "_" #when "\n" "__cfaasm_" #label "_" #when ":":::"memory":when) |
---|
| 235 | |
---|
[8fc652e0] | 236 | //---------- |
---|
| 237 | // special case for preemption since used often |
---|
| 238 | bool __preemption_enabled() { |
---|
| 239 | // create a assembler label before |
---|
| 240 | // marked as clobber all to avoid movement |
---|
[ead174a] | 241 | __cfaasm_label(check, before); |
---|
[8fc652e0] | 242 | |
---|
| 243 | // access tls as normal |
---|
| 244 | bool enabled = __cfaabi_tls.preemption_state.enabled; |
---|
| 245 | |
---|
| 246 | // create a assembler label after |
---|
| 247 | // marked as clobber all to avoid movement |
---|
[ead174a] | 248 | __cfaasm_label(check, after); |
---|
[8fc652e0] | 249 | return enabled; |
---|
| 250 | } |
---|
| 251 | |
---|
[82a2fed] | 252 | struct asm_region { |
---|
| 253 | void * before; |
---|
| 254 | void * after; |
---|
| 255 | }; |
---|
| 256 | |
---|
| 257 | static inline bool __cfaasm_in( void * ip, struct asm_region & region ) { |
---|
| 258 | return ip >= region.before && ip <= region.after; |
---|
| 259 | } |
---|
| 260 | |
---|
| 261 | |
---|
[8fc652e0] | 262 | //---------- |
---|
| 263 | // Get data from the TLS block |
---|
[82a2fed] | 264 | // struct asm_region __cfaasm_get; |
---|
[8fc652e0] | 265 | uintptr_t __cfatls_get( unsigned long int offset ) __attribute__((__noinline__)); //no inline to avoid problems |
---|
| 266 | uintptr_t __cfatls_get( unsigned long int offset ) { |
---|
| 267 | // create a assembler label before |
---|
| 268 | // marked as clobber all to avoid movement |
---|
[ead174a] | 269 | __cfaasm_label(get, before); |
---|
[8fc652e0] | 270 | |
---|
| 271 | // access tls as normal (except for pointer arithmetic) |
---|
| 272 | uintptr_t val = *(uintptr_t*)((uintptr_t)&__cfaabi_tls + offset); |
---|
| 273 | |
---|
| 274 | // create a assembler label after |
---|
| 275 | // marked as clobber all to avoid movement |
---|
[ead174a] | 276 | __cfaasm_label(get, after); |
---|
[8fc652e0] | 277 | return val; |
---|
| 278 | } |
---|
| 279 | |
---|
[82ff5845] | 280 | extern "C" { |
---|
[969b3fe] | 281 | // Disable interrupts by incrementing the counter |
---|
[82ff5845] | 282 | void disable_interrupts() { |
---|
[8fc652e0] | 283 | // create a assembler label before |
---|
| 284 | // marked as clobber all to avoid movement |
---|
[ead174a] | 285 | __cfaasm_label(dsable, before); |
---|
[8fc652e0] | 286 | |
---|
| 287 | with( __cfaabi_tls.preemption_state ) { |
---|
[1f81d61] | 288 | #if GCC_VERSION > 50000 |
---|
[13073be] | 289 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
---|
[1f81d61] | 290 | #endif |
---|
[13073be] | 291 | |
---|
| 292 | // Set enabled flag to false |
---|
| 293 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 294 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
| 295 | __atomic_store_n(&enabled, false, __ATOMIC_RELAXED); |
---|
| 296 | |
---|
| 297 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 298 | __atomic_signal_fence(__ATOMIC_ACQUIRE); |
---|
| 299 | |
---|
[de6319f] | 300 | __attribute__((unused)) unsigned short new_val = disable_count + 1; |
---|
| 301 | disable_count = new_val; |
---|
| 302 | verify( new_val < 65_000u ); // If this triggers someone is disabling interrupts without enabling them |
---|
| 303 | } |
---|
[8fc652e0] | 304 | |
---|
| 305 | // create a assembler label after |
---|
| 306 | // marked as clobber all to avoid movement |
---|
[ead174a] | 307 | __cfaasm_label(dsable, after); |
---|
| 308 | |
---|
[82ff5845] | 309 | } |
---|
| 310 | |
---|
[969b3fe] | 311 | // Enable interrupts by decrementing the counter |
---|
[c7a900a] | 312 | // If counter reaches 0, execute any pending __cfactx_switch |
---|
[36982fc] | 313 | void enable_interrupts( __cfaabi_dbg_ctx_param ) { |
---|
[ead174a] | 314 | // Cache the processor now since interrupts can start happening after the atomic store |
---|
| 315 | processor * proc = __cfaabi_tls.this_processor; |
---|
[8e9e9a2] | 316 | /* paranoid */ verify( proc ); |
---|
[969b3fe] | 317 | |
---|
[8fc652e0] | 318 | with( __cfaabi_tls.preemption_state ){ |
---|
[de6319f] | 319 | unsigned short prev = disable_count; |
---|
| 320 | disable_count -= 1; |
---|
[ead174a] | 321 | |
---|
| 322 | // If this triggers someone is enabled already enabled interruptsverify( prev != 0u ); |
---|
| 323 | /* paranoid */ verify( prev != 0u ); |
---|
[de6319f] | 324 | |
---|
| 325 | // Check if we need to prempt the thread because an interrupt was missed |
---|
| 326 | if( prev == 1 ) { |
---|
[1f81d61] | 327 | #if GCC_VERSION > 50000 |
---|
[ead174a] | 328 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
---|
[1f81d61] | 329 | #endif |
---|
[13073be] | 330 | |
---|
| 331 | // Set enabled flag to true |
---|
| 332 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 333 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
| 334 | __atomic_store_n(&enabled, true, __ATOMIC_RELAXED); |
---|
| 335 | |
---|
| 336 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 337 | __atomic_signal_fence(__ATOMIC_RELEASE); |
---|
[de6319f] | 338 | if( proc->pending_preemption ) { |
---|
| 339 | proc->pending_preemption = false; |
---|
[3381ed7] | 340 | force_yield( __POLL_PREEMPTION ); |
---|
[de6319f] | 341 | } |
---|
[d0a045c7] | 342 | } |
---|
[82ff5845] | 343 | } |
---|
[4e6fb8e] | 344 | |
---|
[969b3fe] | 345 | // For debugging purposes : keep track of the last person to enable the interrupts |
---|
[36982fc] | 346 | __cfaabi_dbg_debug_do( proc->last_enable = caller; ) |
---|
[82ff5845] | 347 | } |
---|
[969b3fe] | 348 | |
---|
| 349 | // Disable interrupts by incrementint the counter |
---|
[c7a900a] | 350 | // Don't execute any pending __cfactx_switch even if counter reaches 0 |
---|
[969b3fe] | 351 | void enable_interrupts_noPoll() { |
---|
[8fc652e0] | 352 | unsigned short prev = __cfaabi_tls.preemption_state.disable_count; |
---|
| 353 | __cfaabi_tls.preemption_state.disable_count -= 1; |
---|
[ead174a] | 354 | // If this triggers someone is enabled already enabled interrupts |
---|
| 355 | /* paranoid */ verifyf( prev != 0u, "Incremented from %u\n", prev ); |
---|
[d0a045c7] | 356 | if( prev == 1 ) { |
---|
[1f81d61] | 357 | #if GCC_VERSION > 50000 |
---|
[ead174a] | 358 | static_assert(__atomic_always_lock_free(sizeof(__cfaabi_tls.preemption_state.enabled), &__cfaabi_tls.preemption_state.enabled), "Must be lock-free"); |
---|
[1f81d61] | 359 | #endif |
---|
[13073be] | 360 | // Set enabled flag to true |
---|
| 361 | // should be atomic to avoid preemption in the middle of the operation. |
---|
| 362 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
---|
[8fc652e0] | 363 | __atomic_store_n(&__cfaabi_tls.preemption_state.enabled, true, __ATOMIC_RELAXED); |
---|
[13073be] | 364 | |
---|
| 365 | // Signal the compiler that a fence is needed but only for signal handlers |
---|
| 366 | __atomic_signal_fence(__ATOMIC_RELEASE); |
---|
[d0a045c7] | 367 | } |
---|
[969b3fe] | 368 | } |
---|
[82ff5845] | 369 | } |
---|
| 370 | |
---|
[adf34b3] | 371 | //----------------------------------------------------------------------------- |
---|
| 372 | // Kernel Signal Debug |
---|
| 373 | void __cfaabi_check_preemption() { |
---|
| 374 | bool ready = __preemption_enabled(); |
---|
| 375 | if(!ready) { abort("Preemption should be ready"); } |
---|
| 376 | |
---|
| 377 | __cfaasm_label(debug, before); |
---|
| 378 | |
---|
| 379 | sigset_t oldset; |
---|
| 380 | int ret; |
---|
| 381 | ret = pthread_sigmask(0, ( const sigset_t * ) 0p, &oldset); // workaround trac#208: cast should be unnecessary |
---|
| 382 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
---|
| 383 | |
---|
| 384 | ret = sigismember(&oldset, SIGUSR1); |
---|
| 385 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 386 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
---|
| 387 | |
---|
| 388 | ret = sigismember(&oldset, SIGALRM); |
---|
| 389 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 390 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
---|
| 391 | |
---|
| 392 | ret = sigismember(&oldset, SIGTERM); |
---|
| 393 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 394 | if(ret == 1) { abort("ERROR SIGTERM is disabled"); } |
---|
| 395 | |
---|
| 396 | __cfaasm_label(debug, after); |
---|
| 397 | } |
---|
| 398 | |
---|
| 399 | #ifdef __CFA_WITH_VERIFY__ |
---|
| 400 | bool __cfaabi_dbg_in_kernel() { |
---|
| 401 | return !__preemption_enabled(); |
---|
| 402 | } |
---|
| 403 | #endif |
---|
| 404 | |
---|
[ead174a] | 405 | #undef __cfaasm_label |
---|
| 406 | |
---|
[adf34b3] | 407 | //----------------------------------------------------------------------------- |
---|
| 408 | // Signal handling |
---|
| 409 | |
---|
[969b3fe] | 410 | // sigprocmask wrapper : unblock a single signal |
---|
[7222630] | 411 | static inline void signal_unblock( int sig ) { |
---|
[82ff5845] | 412 | sigset_t mask; |
---|
| 413 | sigemptyset( &mask ); |
---|
[1c273d0] | 414 | sigaddset( &mask, sig ); |
---|
[82ff5845] | 415 | |
---|
[27f5f71] | 416 | if ( pthread_sigmask( SIG_UNBLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 417 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 418 | } |
---|
[82ff5845] | 419 | } |
---|
| 420 | |
---|
[969b3fe] | 421 | // sigprocmask wrapper : block a single signal |
---|
[7222630] | 422 | static inline void signal_block( int sig ) { |
---|
[cd17862] | 423 | sigset_t mask; |
---|
| 424 | sigemptyset( &mask ); |
---|
| 425 | sigaddset( &mask, sig ); |
---|
[47ecf2b] | 426 | |
---|
[27f5f71] | 427 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[c59a346] | 428 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 429 | } |
---|
| 430 | } |
---|
[47ecf2b] | 431 | |
---|
[969b3fe] | 432 | // kill wrapper : signal a processor |
---|
[cd17862] | 433 | static void preempt( processor * this ) { |
---|
[4dad189] | 434 | sigval_t value = { PREEMPT_NORMAL }; |
---|
| 435 | pthread_sigqueue( this->kernel_thread, SIGUSR1, value ); |
---|
| 436 | } |
---|
| 437 | |
---|
[969b3fe] | 438 | // reserved for future use |
---|
[e873838] | 439 | static void timeout( $thread * this ) { |
---|
| 440 | unpark( this ); |
---|
[cd17862] | 441 | } |
---|
| 442 | |
---|
[7222630] | 443 | void __disable_interrupts_hard() { |
---|
| 444 | sigset_t oldset; |
---|
| 445 | int ret; |
---|
| 446 | ret = pthread_sigmask(0, ( const sigset_t * ) 0p, &oldset); // workaround trac#208: cast should be unnecessary |
---|
| 447 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
---|
| 448 | |
---|
| 449 | ret = sigismember(&oldset, SIGUSR1); |
---|
| 450 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 451 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
---|
| 452 | |
---|
| 453 | ret = sigismember(&oldset, SIGALRM); |
---|
| 454 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 455 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
---|
| 456 | |
---|
| 457 | signal_block( SIGUSR1 ); |
---|
| 458 | } |
---|
| 459 | |
---|
| 460 | void __enable_interrupts_hard() { |
---|
| 461 | signal_unblock( SIGUSR1 ); |
---|
| 462 | |
---|
| 463 | sigset_t oldset; |
---|
| 464 | int ret; |
---|
| 465 | ret = pthread_sigmask(0, ( const sigset_t * ) 0p, &oldset); // workaround trac#208: cast should be unnecessary |
---|
| 466 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
---|
| 467 | |
---|
| 468 | ret = sigismember(&oldset, SIGUSR1); |
---|
| 469 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 470 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
---|
| 471 | |
---|
| 472 | ret = sigismember(&oldset, SIGALRM); |
---|
| 473 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 474 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
---|
| 475 | } |
---|
| 476 | |
---|
[82a2fed] | 477 | //----------------------------------------------------------------------------- |
---|
| 478 | // Some assembly required |
---|
| 479 | #if defined( __i386 ) |
---|
| 480 | #ifdef __PIC__ |
---|
| 481 | #define RELOC_PRELUDE( label ) \ |
---|
| 482 | "calll .Lcfaasm_prelude_" #label "$pb\n\t" \ |
---|
| 483 | ".Lcfaasm_prelude_" #label "$pb:\n\t" \ |
---|
| 484 | "popl %%eax\n\t" \ |
---|
| 485 | ".Lcfaasm_prelude_" #label "_end:\n\t" \ |
---|
| 486 | "addl $_GLOBAL_OFFSET_TABLE_+(.Lcfaasm_prelude_" #label "_end-.Lcfaasm_prelude_" #label "$pb), %%eax\n\t" |
---|
| 487 | #define RELOC_PREFIX "" |
---|
| 488 | #define RELOC_SUFFIX "@GOT(%%eax)" |
---|
| 489 | #else |
---|
| 490 | #define RELOC_PREFIX "$" |
---|
| 491 | #define RELOC_SUFFIX "" |
---|
| 492 | #endif |
---|
[a12810d] | 493 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 494 | ({ \ |
---|
| 495 | struct asm_region region; \ |
---|
| 496 | asm( \ |
---|
| 497 | RELOC_PRELUDE( label ) \ |
---|
| 498 | "movl " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \ |
---|
| 499 | "movl " RELOC_PREFIX "__cfaasm_" #label "_after" RELOC_SUFFIX ", %[va]\n\t" \ |
---|
| 500 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 501 | ); \ |
---|
| 502 | region; \ |
---|
| 503 | }); |
---|
| 504 | #elif defined( __x86_64 ) |
---|
| 505 | #ifdef __PIC__ |
---|
| 506 | #define RELOC_PREFIX "" |
---|
| 507 | #define RELOC_SUFFIX "@GOTPCREL(%%rip)" |
---|
| 508 | #else |
---|
| 509 | #define RELOC_PREFIX "$" |
---|
| 510 | #define RELOC_SUFFIX "" |
---|
| 511 | #endif |
---|
[a12810d] | 512 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 513 | ({ \ |
---|
| 514 | struct asm_region region; \ |
---|
| 515 | asm( \ |
---|
| 516 | "movq " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \ |
---|
| 517 | "movq " RELOC_PREFIX "__cfaasm_" #label "_after" RELOC_SUFFIX ", %[va]\n\t" \ |
---|
| 518 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 519 | ); \ |
---|
| 520 | region; \ |
---|
| 521 | }); |
---|
| 522 | #elif defined( __aarch64__ ) |
---|
| 523 | #ifdef __PIC__ |
---|
[ead174a] | 524 | // Note that this works only for gcc |
---|
[a12810d] | 525 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 526 | ({ \ |
---|
| 527 | struct asm_region region; \ |
---|
| 528 | asm( \ |
---|
[ead174a] | 529 | "adrp %[vb], _GLOBAL_OFFSET_TABLE_" "\n\t" \ |
---|
| 530 | "ldr %[vb], [%[vb], #:gotpage_lo15:__cfaasm_" #label "_before]" "\n\t" \ |
---|
| 531 | "adrp %[va], _GLOBAL_OFFSET_TABLE_" "\n\t" \ |
---|
| 532 | "ldr %[va], [%[va], #:gotpage_lo15:__cfaasm_" #label "_after]" "\n\t" \ |
---|
[82a2fed] | 533 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 534 | ); \ |
---|
| 535 | region; \ |
---|
| 536 | }); |
---|
| 537 | #else |
---|
[ead174a] | 538 | #error this is not the right thing to do |
---|
[b5344a3] | 539 | /* |
---|
[a12810d] | 540 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 541 | ({ \ |
---|
| 542 | struct asm_region region; \ |
---|
| 543 | asm( \ |
---|
[b5344a3] | 544 | "adrp %[vb], __cfaasm_" #label "_before" "\n\t" \ |
---|
| 545 | "add %[vb], %[vb], :lo12:__cfaasm_" #label "_before" "\n\t" \ |
---|
| 546 | "adrp %[va], :got:__cfaasm_" #label "_after" "\n\t" \ |
---|
| 547 | "add %[va], %[va], :lo12:__cfaasm_" #label "_after" "\n\t" \ |
---|
[82a2fed] | 548 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 549 | ); \ |
---|
| 550 | region; \ |
---|
| 551 | }); |
---|
[b5344a3] | 552 | */ |
---|
[ead174a] | 553 | #endif |
---|
[82a2fed] | 554 | #else |
---|
| 555 | #error unknown hardware architecture |
---|
| 556 | #endif |
---|
| 557 | |
---|
[14a61b5] | 558 | // KERNEL ONLY |
---|
[c7a900a] | 559 | // Check if a __cfactx_switch signal handler shoud defer |
---|
[969b3fe] | 560 | // If true : preemption is safe |
---|
| 561 | // If false : preemption is unsafe and marked as pending |
---|
[82a2fed] | 562 | static inline bool preemption_ready( void * ip ) { |
---|
| 563 | // Get all the region for which it is not safe to preempt |
---|
| 564 | __cfaasm_label( get ); |
---|
| 565 | __cfaasm_label( check ); |
---|
| 566 | __cfaasm_label( dsable ); |
---|
[adf34b3] | 567 | __cfaasm_label( debug ); |
---|
[14a61b5] | 568 | |
---|
[82a2fed] | 569 | // Check if preemption is safe |
---|
| 570 | bool ready = true; |
---|
| 571 | if( __cfaasm_in( ip, get ) ) { ready = false; goto EXIT; }; |
---|
| 572 | if( __cfaasm_in( ip, check ) ) { ready = false; goto EXIT; }; |
---|
| 573 | if( __cfaasm_in( ip, dsable ) ) { ready = false; goto EXIT; }; |
---|
[adf34b3] | 574 | if( __cfaasm_in( ip, debug ) ) { ready = false; goto EXIT; }; |
---|
[82a2fed] | 575 | if( !__cfaabi_tls.preemption_state.enabled) { ready = false; goto EXIT; }; |
---|
| 576 | if( __cfaabi_tls.preemption_state.in_progress ) { ready = false; goto EXIT; }; |
---|
| 577 | |
---|
| 578 | EXIT: |
---|
[14a61b5] | 579 | // Adjust the pending flag accordingly |
---|
[8fc652e0] | 580 | __cfaabi_tls.this_processor->pending_preemption = !ready; |
---|
[969b3fe] | 581 | return ready; |
---|
| 582 | } |
---|
| 583 | |
---|
[cd17862] | 584 | //============================================================================================= |
---|
| 585 | // Kernel Signal Startup/Shutdown logic |
---|
| 586 | //============================================================================================= |
---|
| 587 | |
---|
[969b3fe] | 588 | // Startup routine to activate preemption |
---|
| 589 | // Called from kernel_startup |
---|
[e660761] | 590 | void __kernel_alarm_startup() { |
---|
[169d944] | 591 | __cfaabi_dbg_print_safe( "Kernel : Starting preemption\n" ); |
---|
[969b3fe] | 592 | |
---|
| 593 | // Start with preemption disabled until ready |
---|
[8fc652e0] | 594 | __cfaabi_tls.preemption_state.enabled = false; |
---|
| 595 | __cfaabi_tls.preemption_state.disable_count = 1; |
---|
[969b3fe] | 596 | |
---|
| 597 | // Initialize the event kernel |
---|
| 598 | event_kernel = (event_kernel_t *)&storage_event_kernel; |
---|
[9236060] | 599 | (*event_kernel){}; |
---|
[969b3fe] | 600 | |
---|
| 601 | // Setup proper signal handlers |
---|
[6047b00] | 602 | __cfaabi_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO ); // __cfactx_switch handler |
---|
| 603 | __cfaabi_sigaction( SIGALRM, sigHandler_alarm , SA_SIGINFO ); // debug handler |
---|
[cd17862] | 604 | |
---|
| 605 | signal_block( SIGALRM ); |
---|
| 606 | |
---|
[8c50aed] | 607 | alarm_stack = __create_pthread( &alarm_thread, alarm_loop, 0p ); |
---|
[cd17862] | 608 | } |
---|
| 609 | |
---|
[969b3fe] | 610 | // Shutdown routine to deactivate preemption |
---|
| 611 | // Called from kernel_shutdown |
---|
[e660761] | 612 | void __kernel_alarm_shutdown() { |
---|
[169d944] | 613 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopping\n" ); |
---|
[d6ff3ff] | 614 | |
---|
[969b3fe] | 615 | // Block all signals since we are already shutting down |
---|
[cd17862] | 616 | sigset_t mask; |
---|
| 617 | sigfillset( &mask ); |
---|
[27f5f71] | 618 | sigprocmask( SIG_BLOCK, &mask, 0p ); |
---|
[cd17862] | 619 | |
---|
[969b3fe] | 620 | // Notify the alarm thread of the shutdown |
---|
[a0b3e32] | 621 | sigval val = { 1 }; |
---|
| 622 | pthread_sigqueue( alarm_thread, SIGALRM, val ); |
---|
[969b3fe] | 623 | |
---|
| 624 | // Wait for the preemption thread to finish |
---|
[27f5f71] | 625 | |
---|
[bfcf6b9] | 626 | __destroy_pthread( alarm_thread, alarm_stack, 0p ); |
---|
[969b3fe] | 627 | |
---|
| 628 | // Preemption is now fully stopped |
---|
| 629 | |
---|
[169d944] | 630 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopped\n" ); |
---|
[cd17862] | 631 | } |
---|
| 632 | |
---|
[92bfda0] | 633 | // Prevent preemption since we are about to start terminating things |
---|
| 634 | void __kernel_abort_lock(void) { |
---|
| 635 | signal_block( SIGUSR1 ); |
---|
| 636 | } |
---|
| 637 | |
---|
[969b3fe] | 638 | // Raii ctor/dtor for the preemption_scope |
---|
| 639 | // Used by thread to control when they want to receive preemption signals |
---|
[242a902] | 640 | void ?{}( preemption_scope & this, processor * proc ) { |
---|
[2a84d06d] | 641 | (this.alarm){ proc, (Time){ 0 }, 0`s }; |
---|
[242a902] | 642 | this.proc = proc; |
---|
| 643 | this.proc->preemption_alarm = &this.alarm; |
---|
[969b3fe] | 644 | |
---|
[d8548e2] | 645 | update_preemption( this.proc, this.proc->cltr->preemption_rate ); |
---|
[cd17862] | 646 | } |
---|
| 647 | |
---|
[242a902] | 648 | void ^?{}( preemption_scope & this ) { |
---|
[cd17862] | 649 | disable_interrupts(); |
---|
| 650 | |
---|
[2a84d06d] | 651 | update_preemption( this.proc, 0`s ); |
---|
[cd17862] | 652 | } |
---|
| 653 | |
---|
| 654 | //============================================================================================= |
---|
| 655 | // Kernel Signal Handlers |
---|
| 656 | //============================================================================================= |
---|
[54dcab1] | 657 | __cfaabi_dbg_debug_do( static thread_local void * last_interrupt = 0; ) |
---|
[47ecf2b] | 658 | |
---|
[969b3fe] | 659 | // Context switch signal handler |
---|
| 660 | // Receives SIGUSR1 signal and causes the current thread to yield |
---|
[c29c342] | 661 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) { |
---|
[8fc652e0] | 662 | void * ip = (void *)(cxt->uc_mcontext.CFA_REG_IP); |
---|
| 663 | __cfaabi_dbg_debug_do( last_interrupt = ip; ) |
---|
[969b3fe] | 664 | |
---|
[4dad189] | 665 | // SKULLDUGGERY: if a thread creates a processor and the immediately deletes it, |
---|
| 666 | // the interrupt that is supposed to force the kernel thread to preempt might arrive |
---|
[482fa08] | 667 | // before the kernel thread has even started running. When that happens, an interrupt |
---|
[97cba9f] | 668 | // with a null 'this_processor' will be caught, just ignore it. |
---|
[8fc652e0] | 669 | if(! __cfaabi_tls.this_processor ) return; |
---|
[4dad189] | 670 | |
---|
| 671 | choose(sfp->si_value.sival_int) { |
---|
| 672 | case PREEMPT_NORMAL : ;// Normal case, nothing to do here |
---|
[8fc652e0] | 673 | case PREEMPT_TERMINATE: verify( __atomic_load_n( &__cfaabi_tls.this_processor->do_terminate, __ATOMIC_SEQ_CST ) ); |
---|
[4dad189] | 674 | default: |
---|
[ff878b7] | 675 | abort( "internal error, signal value is %d", sfp->si_value.sival_int ); |
---|
[4dad189] | 676 | } |
---|
| 677 | |
---|
[b2b44d8] | 678 | // Check if it is safe to preempt here |
---|
[82a2fed] | 679 | if( !preemption_ready( ip ) ) { return; } |
---|
[8fc652e0] | 680 | |
---|
| 681 | __cfaabi_dbg_print_buffer_decl( " KERNEL: preempting core %p (%p @ %p).\n", __cfaabi_tls.this_processor, __cfaabi_tls.this_thread, (void *)(cxt->uc_mcontext.CFA_REG_IP) ); |
---|
[14a61b5] | 682 | |
---|
| 683 | // Sync flag : prevent recursive calls to the signal handler |
---|
[8fc652e0] | 684 | __cfaabi_tls.preemption_state.in_progress = true; |
---|
[14a61b5] | 685 | |
---|
[a83ffa4] | 686 | // Clear sighandler mask before context switching. |
---|
[1f81d61] | 687 | #if GCC_VERSION > 50000 |
---|
[a83ffa4] | 688 | static_assert( sizeof( sigset_t ) == sizeof( cxt->uc_sigmask ), "Expected cxt->uc_sigmask to be of sigset_t" ); |
---|
[1f81d61] | 689 | #endif |
---|
[27f5f71] | 690 | if ( pthread_sigmask( SIG_SETMASK, (sigset_t *)&(cxt->uc_sigmask), 0p ) == -1 ) { |
---|
[a83ffa4] | 691 | abort( "internal error, sigprocmask" ); |
---|
| 692 | } |
---|
[05615ba] | 693 | |
---|
[14a61b5] | 694 | // Clear the in progress flag |
---|
[8fc652e0] | 695 | __cfaabi_tls.preemption_state.in_progress = false; |
---|
[969b3fe] | 696 | |
---|
| 697 | // Preemption can occur here |
---|
| 698 | |
---|
[c7a900a] | 699 | force_yield( __ALARM_PREEMPTION ); // Do the actual __cfactx_switch |
---|
[c81ebf9] | 700 | } |
---|
| 701 | |
---|
[c59a346] | 702 | static void sigHandler_alarm( __CFA_SIGPARMS__ ) { |
---|
| 703 | abort("SIGALRM should never reach the signal handler"); |
---|
[c81ebf9] | 704 | } |
---|
| 705 | |
---|
[1b033b8] | 706 | #if !defined(__CFA_NO_STATISTICS__) |
---|
| 707 | int __print_alarm_stats = 0; |
---|
| 708 | #endif |
---|
| 709 | |
---|
[969b3fe] | 710 | // Main of the alarm thread |
---|
| 711 | // Waits on SIGALRM and send SIGUSR1 to whom ever needs it |
---|
[c29c342] | 712 | static void * alarm_loop( __attribute__((unused)) void * args ) { |
---|
[9b1dcc2] | 713 | __processor_id_t id; |
---|
[58d64a4] | 714 | id.full_proc = false; |
---|
[9b1dcc2] | 715 | id.id = doregister(&id); |
---|
[8fc652e0] | 716 | __cfaabi_tls.this_proc_id = &id; |
---|
[9b1dcc2] | 717 | |
---|
[1b033b8] | 718 | #if !defined(__CFA_NO_STATISTICS__) |
---|
| 719 | struct __stats_t local_stats; |
---|
| 720 | __cfaabi_tls.this_stats = &local_stats; |
---|
| 721 | __init_stats( &local_stats ); |
---|
| 722 | #endif |
---|
| 723 | |
---|
[969b3fe] | 724 | // Block sigalrms to control when they arrive |
---|
[cd17862] | 725 | sigset_t mask; |
---|
[ade5272] | 726 | sigfillset(&mask); |
---|
[27f5f71] | 727 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 728 | abort( "internal error, pthread_sigmask" ); |
---|
[82ff5845] | 729 | } |
---|
[c81ebf9] | 730 | |
---|
[ade5272] | 731 | sigemptyset( &mask ); |
---|
| 732 | sigaddset( &mask, SIGALRM ); |
---|
| 733 | |
---|
[969b3fe] | 734 | // Main loop |
---|
[cd17862] | 735 | while( true ) { |
---|
[969b3fe] | 736 | // Wait for a sigalrm |
---|
[a0b3e32] | 737 | siginfo_t info; |
---|
| 738 | int sig = sigwaitinfo( &mask, &info ); |
---|
[969b3fe] | 739 | |
---|
[e2f7bc3] | 740 | if( sig < 0 ) { |
---|
| 741 | //Error! |
---|
| 742 | int err = errno; |
---|
| 743 | switch( err ) { |
---|
| 744 | case EAGAIN : |
---|
| 745 | case EINTR : |
---|
[b1a4300] | 746 | {__cfaabi_dbg_print_buffer_decl( " KERNEL: Spurious wakeup %d.\n", err );} |
---|
[e2f7bc3] | 747 | continue; |
---|
[27f5f71] | 748 | case EINVAL : |
---|
[169d944] | 749 | abort( "Timeout was invalid." ); |
---|
[e2f7bc3] | 750 | default: |
---|
[169d944] | 751 | abort( "Unhandled error %d", err); |
---|
[e2f7bc3] | 752 | } |
---|
| 753 | } |
---|
| 754 | |
---|
[969b3fe] | 755 | // If another signal arrived something went wrong |
---|
[8cb529e] | 756 | assertf(sig == SIGALRM, "Kernel Internal Error, sigwait: Unexpected signal %d (%d : %d)\n", sig, info.si_code, info.si_value.sival_int); |
---|
| 757 | |
---|
[169d944] | 758 | // __cfaabi_dbg_print_safe( "Kernel : Caught alarm from %d with %d\n", info.si_code, info.si_value.sival_int ); |
---|
[969b3fe] | 759 | // Switch on the code (a.k.a. the sender) to |
---|
[8cb529e] | 760 | switch( info.si_code ) |
---|
[a0b3e32] | 761 | { |
---|
[969b3fe] | 762 | // Timers can apparently be marked as sent for the kernel |
---|
| 763 | // In either case, tick preemption |
---|
[8cb529e] | 764 | case SI_TIMER: |
---|
| 765 | case SI_KERNEL: |
---|
[169d944] | 766 | // __cfaabi_dbg_print_safe( "Kernel : Preemption thread tick\n" ); |
---|
[36982fc] | 767 | lock( event_kernel->lock __cfaabi_dbg_ctx2 ); |
---|
[e873838] | 768 | tick_preemption(); |
---|
[ea7d2b0] | 769 | unlock( event_kernel->lock ); |
---|
[8cb529e] | 770 | break; |
---|
[969b3fe] | 771 | // Signal was not sent by the kernel but by an other thread |
---|
[8cb529e] | 772 | case SI_QUEUE: |
---|
[969b3fe] | 773 | // For now, other thread only signal the alarm thread to shut it down |
---|
| 774 | // If this needs to change use info.si_value and handle the case here |
---|
[8cb529e] | 775 | goto EXIT; |
---|
[cd17862] | 776 | } |
---|
| 777 | } |
---|
[a0b3e32] | 778 | |
---|
[8cb529e] | 779 | EXIT: |
---|
[169d944] | 780 | __cfaabi_dbg_print_safe( "Kernel : Preemption thread stopping\n" ); |
---|
[9b1dcc2] | 781 | unregister(&id); |
---|
[1b033b8] | 782 | |
---|
| 783 | #if !defined(__CFA_NO_STATISTICS__) |
---|
| 784 | if( 0 != __print_alarm_stats ) { |
---|
| 785 | __print_stats( &local_stats, __print_alarm_stats, "Alarm", "Thread", 0p ); |
---|
| 786 | } |
---|
| 787 | #endif |
---|
[27f5f71] | 788 | return 0p; |
---|
[82ff5845] | 789 | } |
---|
| 790 | |
---|
[6b0b624] | 791 | // Local Variables: // |
---|
| 792 | // mode: c // |
---|
| 793 | // tab-width: 4 // |
---|
| 794 | // End: // |
---|