[c81ebf9] | 1 | // |
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
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| 3 | // |
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| 4 | // The contents of this file are covered under the licence agreement in the |
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| 5 | // file "LICENCE" distributed with Cforall. |
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| 6 | // |
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| 7 | // signal.c -- |
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| 8 | // |
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| 9 | // Author : Thierry Delisle |
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| 10 | // Created On : Mon Jun 5 14:20:42 2017 |
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[6b0b624] | 11 | // Last Modified By : Peter A. Buhr |
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[8ad6533] | 12 | // Last Modified On : Mon Apr 9 13:52:39 2018 |
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| 13 | // Update Count : 36 |
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[c81ebf9] | 14 | // |
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| 15 | |
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| 16 | #include "preemption.h" |
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| 17 | |
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| 18 | extern "C" { |
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[82ff5845] | 19 | #include <errno.h> |
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| 20 | #include <stdio.h> |
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| 21 | #include <string.h> |
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| 22 | #include <unistd.h> |
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[c81ebf9] | 23 | } |
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| 24 | |
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[dbe9b08] | 25 | #include "bits/signal.h" |
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[82ff5845] | 26 | |
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[d8548e2] | 27 | #if !defined(__CFA_DEFAULT_PREEMPTION__) |
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[2a84d06d] | 28 | #define __CFA_DEFAULT_PREEMPTION__ 10`ms |
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[d8548e2] | 29 | #endif |
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[c81ebf9] | 30 | |
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[2a84d06d] | 31 | Duration default_preemption() __attribute__((weak)) { |
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[c81ebf9] | 32 | return __CFA_DEFAULT_PREEMPTION__; |
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| 33 | } |
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| 34 | |
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[969b3fe] | 35 | // FwdDeclarations : timeout handlers |
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[c81ebf9] | 36 | static void preempt( processor * this ); |
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| 37 | static void timeout( thread_desc * this ); |
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| 38 | |
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[969b3fe] | 39 | // FwdDeclarations : Signal handlers |
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[82ff5845] | 40 | void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ); |
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[1c273d0] | 41 | void sigHandler_segv ( __CFA_SIGPARMS__ ); |
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[2b8bc41] | 42 | void sigHandler_ill ( __CFA_SIGPARMS__ ); |
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| 43 | void sigHandler_fpe ( __CFA_SIGPARMS__ ); |
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[1c273d0] | 44 | void sigHandler_abort ( __CFA_SIGPARMS__ ); |
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[82ff5845] | 45 | |
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[969b3fe] | 46 | // FwdDeclarations : alarm thread main |
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| 47 | void * alarm_loop( __attribute__((unused)) void * args ); |
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| 48 | |
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| 49 | // Machine specific register name |
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[381fdee] | 50 | #if defined( __i386 ) |
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[b2b44d8] | 51 | #define CFA_REG_IP gregs[REG_EIP] |
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[381fdee] | 52 | #elif defined( __x86_64 ) |
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| 53 | #define CFA_REG_IP gregs[REG_RIP] |
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| 54 | #elif defined( __ARM_ARCH ) |
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[b2b44d8] | 55 | #define CFA_REG_IP arm_pc |
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[381fdee] | 56 | #else |
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| 57 | #error unknown hardware architecture |
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[cd17862] | 58 | #endif |
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| 59 | |
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[969b3fe] | 60 | KERNEL_STORAGE(event_kernel_t, event_kernel); // private storage for event kernel |
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| 61 | event_kernel_t * event_kernel; // kernel public handle to even kernel |
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| 62 | static pthread_t alarm_thread; // pthread handle to alarm thread |
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| 63 | |
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[65deb18] | 64 | void ?{}(event_kernel_t & this) with( this ) { |
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| 65 | alarms{}; |
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| 66 | lock{}; |
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[969b3fe] | 67 | } |
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[82ff5845] | 68 | |
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[4dad189] | 69 | enum { |
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| 70 | PREEMPT_NORMAL = 0, |
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| 71 | PREEMPT_TERMINATE = 1, |
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| 72 | }; |
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| 73 | |
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[c81ebf9] | 74 | //============================================================================================= |
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| 75 | // Kernel Preemption logic |
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| 76 | //============================================================================================= |
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| 77 | |
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[969b3fe] | 78 | // Get next expired node |
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[2a84d06d] | 79 | static inline alarm_node_t * get_expired( alarm_list_t * alarms, Time currtime ) { |
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[969b3fe] | 80 | if( !alarms->head ) return NULL; // If no alarms return null |
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| 81 | if( alarms->head->alarm >= currtime ) return NULL; // If alarms head not expired return null |
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| 82 | return pop(alarms); // Otherwise just pop head |
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| 83 | } |
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| 84 | |
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| 85 | // Tick one frame of the Discrete Event Simulation for alarms |
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[c81ebf9] | 86 | void tick_preemption() { |
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[969b3fe] | 87 | alarm_node_t * node = NULL; // Used in the while loop but cannot be declared in the while condition |
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| 88 | alarm_list_t * alarms = &event_kernel->alarms; // Local copy for ease of reading |
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[2a84d06d] | 89 | Time currtime = __kernel_get_time(); // Check current time once so we everything "happens at once" |
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[8cb529e] | 90 | |
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[969b3fe] | 91 | //Loop throught every thing expired |
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| 92 | while( node = get_expired( alarms, currtime ) ) { |
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[1c273d0] | 93 | |
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[969b3fe] | 94 | // Check if this is a kernel |
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[c81ebf9] | 95 | if( node->kernel_alarm ) { |
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| 96 | preempt( node->proc ); |
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| 97 | } |
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| 98 | else { |
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| 99 | timeout( node->thrd ); |
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| 100 | } |
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| 101 | |
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[969b3fe] | 102 | // Check if this is a periodic alarm |
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[2a84d06d] | 103 | Duration period = node->period; |
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[8cb529e] | 104 | if( period > 0 ) { |
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[969b3fe] | 105 | node->alarm = currtime + period; // Alarm is periodic, add currtime to it (used cached current time) |
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| 106 | insert( alarms, node ); // Reinsert the node for the next time it triggers |
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[c81ebf9] | 107 | } |
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| 108 | else { |
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[969b3fe] | 109 | node->set = false; // Node is one-shot, just mark it as not pending |
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[c81ebf9] | 110 | } |
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| 111 | } |
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| 112 | |
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[969b3fe] | 113 | // If there are still alarms pending, reset the timer |
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| 114 | if( alarms->head ) { __kernel_set_timer( alarms->head->alarm - currtime ); } |
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[c81ebf9] | 115 | } |
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| 116 | |
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[969b3fe] | 117 | // Update the preemption of a processor and notify interested parties |
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[2a84d06d] | 118 | void update_preemption( processor * this, Duration duration ) { |
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[c81ebf9] | 119 | alarm_node_t * alarm = this->preemption_alarm; |
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| 120 | |
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| 121 | // Alarms need to be enabled |
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[2a84d06d] | 122 | if ( duration > 0 && ! alarm->set ) { |
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[c81ebf9] | 123 | alarm->alarm = __kernel_get_time() + duration; |
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| 124 | alarm->period = duration; |
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| 125 | register_self( alarm ); |
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| 126 | } |
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[8ad6533] | 127 | // Zero duration but alarm is set |
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[c81ebf9] | 128 | else if ( duration == 0 && alarm->set ) { |
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| 129 | unregister_self( alarm ); |
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| 130 | alarm->alarm = 0; |
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| 131 | alarm->period = 0; |
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| 132 | } |
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| 133 | // If alarm is different from previous, change it |
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| 134 | else if ( duration > 0 && alarm->period != duration ) { |
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| 135 | unregister_self( alarm ); |
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| 136 | alarm->alarm = __kernel_get_time() + duration; |
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| 137 | alarm->period = duration; |
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| 138 | register_self( alarm ); |
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| 139 | } |
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| 140 | } |
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| 141 | |
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| 142 | //============================================================================================= |
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[cd17862] | 143 | // Kernel Signal Tools |
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[c81ebf9] | 144 | //============================================================================================= |
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| 145 | |
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[36982fc] | 146 | __cfaabi_dbg_debug_do( static thread_local void * last_interrupt = 0; ) |
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[b227f68] | 147 | |
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[82ff5845] | 148 | extern "C" { |
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[969b3fe] | 149 | // Disable interrupts by incrementing the counter |
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[82ff5845] | 150 | void disable_interrupts() { |
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[afd550c] | 151 | with( kernelTLS.preemption_state ) { |
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[de6319f] | 152 | enabled = false; |
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| 153 | __attribute__((unused)) unsigned short new_val = disable_count + 1; |
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| 154 | disable_count = new_val; |
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| 155 | verify( new_val < 65_000u ); // If this triggers someone is disabling interrupts without enabling them |
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| 156 | } |
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[82ff5845] | 157 | } |
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| 158 | |
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[969b3fe] | 159 | // Enable interrupts by decrementing the counter |
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| 160 | // If counter reaches 0, execute any pending CtxSwitch |
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[36982fc] | 161 | void enable_interrupts( __cfaabi_dbg_ctx_param ) { |
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[afd550c] | 162 | processor * proc = kernelTLS.this_processor; // Cache the processor now since interrupts can start happening after the atomic add |
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| 163 | thread_desc * thrd = kernelTLS.this_thread; // Cache the thread now since interrupts can start happening after the atomic add |
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[969b3fe] | 164 | |
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[afd550c] | 165 | with( kernelTLS.preemption_state ){ |
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[de6319f] | 166 | unsigned short prev = disable_count; |
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| 167 | disable_count -= 1; |
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| 168 | verify( prev != 0u ); // If this triggers someone is enabled already enabled interruptsverify( prev != 0u ); |
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| 169 | |
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| 170 | // Check if we need to prempt the thread because an interrupt was missed |
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| 171 | if( prev == 1 ) { |
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| 172 | enabled = true; |
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| 173 | if( proc->pending_preemption ) { |
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| 174 | proc->pending_preemption = false; |
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| 175 | BlockInternal( thrd ); |
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| 176 | } |
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[d0a045c7] | 177 | } |
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[82ff5845] | 178 | } |
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[4e6fb8e] | 179 | |
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[969b3fe] | 180 | // For debugging purposes : keep track of the last person to enable the interrupts |
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[36982fc] | 181 | __cfaabi_dbg_debug_do( proc->last_enable = caller; ) |
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[82ff5845] | 182 | } |
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[969b3fe] | 183 | |
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| 184 | // Disable interrupts by incrementint the counter |
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| 185 | // Don't execute any pending CtxSwitch even if counter reaches 0 |
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| 186 | void enable_interrupts_noPoll() { |
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[afd550c] | 187 | unsigned short prev = kernelTLS.preemption_state.disable_count; |
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| 188 | kernelTLS.preemption_state.disable_count -= 1; |
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[2e9aed4] | 189 | verifyf( prev != 0u, "Incremented from %u\n", prev ); // If this triggers someone is enabled already enabled interrupts |
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[d0a045c7] | 190 | if( prev == 1 ) { |
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[afd550c] | 191 | kernelTLS.preemption_state.enabled = true; |
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[d0a045c7] | 192 | } |
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[969b3fe] | 193 | } |
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[82ff5845] | 194 | } |
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| 195 | |
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[969b3fe] | 196 | // sigprocmask wrapper : unblock a single signal |
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[1c273d0] | 197 | static inline void signal_unblock( int sig ) { |
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[82ff5845] | 198 | sigset_t mask; |
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| 199 | sigemptyset( &mask ); |
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[1c273d0] | 200 | sigaddset( &mask, sig ); |
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[82ff5845] | 201 | |
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[47ecf2b] | 202 | if ( pthread_sigmask( SIG_UNBLOCK, &mask, NULL ) == -1 ) { |
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[169d944] | 203 | abort( "internal error, pthread_sigmask" ); |
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[cd17862] | 204 | } |
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[82ff5845] | 205 | } |
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| 206 | |
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[969b3fe] | 207 | // sigprocmask wrapper : block a single signal |
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[cd17862] | 208 | static inline void signal_block( int sig ) { |
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| 209 | sigset_t mask; |
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| 210 | sigemptyset( &mask ); |
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| 211 | sigaddset( &mask, sig ); |
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[47ecf2b] | 212 | |
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[cd17862] | 213 | if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) { |
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[169d944] | 214 | abort( "internal error, pthread_sigmask" ); |
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[cd17862] | 215 | } |
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| 216 | } |
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[47ecf2b] | 217 | |
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[969b3fe] | 218 | // kill wrapper : signal a processor |
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[cd17862] | 219 | static void preempt( processor * this ) { |
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[4dad189] | 220 | sigval_t value = { PREEMPT_NORMAL }; |
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| 221 | pthread_sigqueue( this->kernel_thread, SIGUSR1, value ); |
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| 222 | } |
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| 223 | |
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| 224 | // kill wrapper : signal a processor |
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| 225 | void terminate(processor * this) { |
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| 226 | this->do_terminate = true; |
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| 227 | sigval_t value = { PREEMPT_TERMINATE }; |
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| 228 | pthread_sigqueue( this->kernel_thread, SIGUSR1, value ); |
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[1c273d0] | 229 | } |
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[82ff5845] | 230 | |
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[969b3fe] | 231 | // reserved for future use |
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[cd17862] | 232 | static void timeout( thread_desc * this ) { |
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| 233 | //TODO : implement waking threads |
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| 234 | } |
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| 235 | |
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[14a61b5] | 236 | // KERNEL ONLY |
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[969b3fe] | 237 | // Check if a CtxSwitch signal handler shoud defer |
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| 238 | // If true : preemption is safe |
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| 239 | // If false : preemption is unsafe and marked as pending |
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| 240 | static inline bool preemption_ready() { |
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[14a61b5] | 241 | // Check if preemption is safe |
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| 242 | bool ready = kernelTLS.preemption_state.enabled && ! kernelTLS.preemption_state.in_progress; |
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| 243 | |
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| 244 | // Adjust the pending flag accordingly |
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| 245 | kernelTLS.this_processor->pending_preemption = !ready; |
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[969b3fe] | 246 | return ready; |
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| 247 | } |
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| 248 | |
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[cd17862] | 249 | //============================================================================================= |
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| 250 | // Kernel Signal Startup/Shutdown logic |
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| 251 | //============================================================================================= |
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| 252 | |
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[969b3fe] | 253 | // Startup routine to activate preemption |
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| 254 | // Called from kernel_startup |
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[cd17862] | 255 | void kernel_start_preemption() { |
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[169d944] | 256 | __cfaabi_dbg_print_safe( "Kernel : Starting preemption\n" ); |
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[969b3fe] | 257 | |
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| 258 | // Start with preemption disabled until ready |
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[14a61b5] | 259 | kernelTLS.preemption_state.enabled = false; |
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| 260 | kernelTLS.preemption_state.disable_count = 1; |
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[969b3fe] | 261 | |
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| 262 | // Initialize the event kernel |
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| 263 | event_kernel = (event_kernel_t *)&storage_event_kernel; |
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[9236060] | 264 | (*event_kernel){}; |
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[969b3fe] | 265 | |
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| 266 | // Setup proper signal handlers |
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[2b8bc41] | 267 | __cfaabi_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO | SA_RESTART ); // CtxSwitch handler |
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[cd17862] | 268 | |
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| 269 | signal_block( SIGALRM ); |
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| 270 | |
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| 271 | pthread_create( &alarm_thread, NULL, alarm_loop, NULL ); |
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| 272 | } |
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| 273 | |
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[969b3fe] | 274 | // Shutdown routine to deactivate preemption |
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| 275 | // Called from kernel_shutdown |
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[cd17862] | 276 | void kernel_stop_preemption() { |
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[169d944] | 277 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopping\n" ); |
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[d6ff3ff] | 278 | |
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[969b3fe] | 279 | // Block all signals since we are already shutting down |
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[cd17862] | 280 | sigset_t mask; |
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| 281 | sigfillset( &mask ); |
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| 282 | sigprocmask( SIG_BLOCK, &mask, NULL ); |
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| 283 | |
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[969b3fe] | 284 | // Notify the alarm thread of the shutdown |
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[a0b3e32] | 285 | sigval val = { 1 }; |
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| 286 | pthread_sigqueue( alarm_thread, SIGALRM, val ); |
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[969b3fe] | 287 | |
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| 288 | // Wait for the preemption thread to finish |
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[cd17862] | 289 | pthread_join( alarm_thread, NULL ); |
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[969b3fe] | 290 | |
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| 291 | // Preemption is now fully stopped |
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| 292 | |
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[169d944] | 293 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopped\n" ); |
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[cd17862] | 294 | } |
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| 295 | |
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[969b3fe] | 296 | // Raii ctor/dtor for the preemption_scope |
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| 297 | // Used by thread to control when they want to receive preemption signals |
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[242a902] | 298 | void ?{}( preemption_scope & this, processor * proc ) { |
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[2a84d06d] | 299 | (this.alarm){ proc, (Time){ 0 }, 0`s }; |
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[242a902] | 300 | this.proc = proc; |
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| 301 | this.proc->preemption_alarm = &this.alarm; |
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[969b3fe] | 302 | |
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[d8548e2] | 303 | update_preemption( this.proc, this.proc->cltr->preemption_rate ); |
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[cd17862] | 304 | } |
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| 305 | |
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[242a902] | 306 | void ^?{}( preemption_scope & this ) { |
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[cd17862] | 307 | disable_interrupts(); |
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| 308 | |
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[2a84d06d] | 309 | update_preemption( this.proc, 0`s ); |
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[cd17862] | 310 | } |
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| 311 | |
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| 312 | //============================================================================================= |
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| 313 | // Kernel Signal Handlers |
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| 314 | //============================================================================================= |
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[47ecf2b] | 315 | |
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[969b3fe] | 316 | // Context switch signal handler |
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| 317 | // Receives SIGUSR1 signal and causes the current thread to yield |
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[1c273d0] | 318 | void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) { |
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[b2b44d8] | 319 | __cfaabi_dbg_debug_do( last_interrupt = (void *)(cxt->uc_mcontext.CFA_REG_IP); ) |
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[969b3fe] | 320 | |
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[4dad189] | 321 | // SKULLDUGGERY: if a thread creates a processor and the immediately deletes it, |
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| 322 | // the interrupt that is supposed to force the kernel thread to preempt might arrive |
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| 323 | // before the kernel thread has even started running. When that happens an iterrupt |
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| 324 | // we a null 'this_processor' will be caught, just ignore it. |
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[14a61b5] | 325 | if(! kernelTLS.this_processor ) return; |
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[4dad189] | 326 | |
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| 327 | choose(sfp->si_value.sival_int) { |
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| 328 | case PREEMPT_NORMAL : ;// Normal case, nothing to do here |
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[14a61b5] | 329 | case PREEMPT_TERMINATE: verify( kernelTLS.this_processor->do_terminate); |
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[4dad189] | 330 | default: |
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[ff878b7] | 331 | abort( "internal error, signal value is %d", sfp->si_value.sival_int ); |
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[4dad189] | 332 | } |
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| 333 | |
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[b2b44d8] | 334 | // Check if it is safe to preempt here |
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[969b3fe] | 335 | if( !preemption_ready() ) { return; } |
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| 336 | |
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[14a61b5] | 337 | __cfaabi_dbg_print_buffer_decl( " KERNEL: preempting core %p (%p).\n", kernelTLS.this_processor, kernelTLS.this_thread ); |
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| 338 | |
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| 339 | // Sync flag : prevent recursive calls to the signal handler |
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| 340 | kernelTLS.preemption_state.in_progress = true; |
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| 341 | |
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| 342 | // We are about to CtxSwitch out of the signal handler, let other handlers in |
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| 343 | signal_unblock( SIGUSR1 ); |
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[05615ba] | 344 | |
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[14a61b5] | 345 | // TODO: this should go in finish action |
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| 346 | // Clear the in progress flag |
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| 347 | kernelTLS.preemption_state.in_progress = false; |
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[969b3fe] | 348 | |
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| 349 | // Preemption can occur here |
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| 350 | |
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[14a61b5] | 351 | BlockInternal( kernelTLS.this_thread ); // Do the actual CtxSwitch |
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[c81ebf9] | 352 | } |
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| 353 | |
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[969b3fe] | 354 | // Main of the alarm thread |
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| 355 | // Waits on SIGALRM and send SIGUSR1 to whom ever needs it |
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[cd17862] | 356 | void * alarm_loop( __attribute__((unused)) void * args ) { |
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[969b3fe] | 357 | // Block sigalrms to control when they arrive |
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[cd17862] | 358 | sigset_t mask; |
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[ade5272] | 359 | sigfillset(&mask); |
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[cd17862] | 360 | if ( pthread_sigmask( SIG_BLOCK, &mask, NULL ) == -1 ) { |
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[169d944] | 361 | abort( "internal error, pthread_sigmask" ); |
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[82ff5845] | 362 | } |
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[c81ebf9] | 363 | |
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[ade5272] | 364 | sigemptyset( &mask ); |
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| 365 | sigaddset( &mask, SIGALRM ); |
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| 366 | |
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[969b3fe] | 367 | // Main loop |
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[cd17862] | 368 | while( true ) { |
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[969b3fe] | 369 | // Wait for a sigalrm |
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[a0b3e32] | 370 | siginfo_t info; |
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| 371 | int sig = sigwaitinfo( &mask, &info ); |
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[969b3fe] | 372 | |
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[e2f7bc3] | 373 | if( sig < 0 ) { |
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| 374 | //Error! |
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| 375 | int err = errno; |
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| 376 | switch( err ) { |
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| 377 | case EAGAIN : |
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| 378 | case EINTR : |
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| 379 | continue; |
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| 380 | case EINVAL : |
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[169d944] | 381 | abort( "Timeout was invalid." ); |
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[e2f7bc3] | 382 | default: |
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[169d944] | 383 | abort( "Unhandled error %d", err); |
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[e2f7bc3] | 384 | } |
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| 385 | } |
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| 386 | |
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[969b3fe] | 387 | // If another signal arrived something went wrong |
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[8cb529e] | 388 | assertf(sig == SIGALRM, "Kernel Internal Error, sigwait: Unexpected signal %d (%d : %d)\n", sig, info.si_code, info.si_value.sival_int); |
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| 389 | |
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[169d944] | 390 | // __cfaabi_dbg_print_safe( "Kernel : Caught alarm from %d with %d\n", info.si_code, info.si_value.sival_int ); |
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[969b3fe] | 391 | // Switch on the code (a.k.a. the sender) to |
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[8cb529e] | 392 | switch( info.si_code ) |
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[a0b3e32] | 393 | { |
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[969b3fe] | 394 | // Timers can apparently be marked as sent for the kernel |
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| 395 | // In either case, tick preemption |
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[8cb529e] | 396 | case SI_TIMER: |
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| 397 | case SI_KERNEL: |
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[169d944] | 398 | // __cfaabi_dbg_print_safe( "Kernel : Preemption thread tick\n" ); |
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[36982fc] | 399 | lock( event_kernel->lock __cfaabi_dbg_ctx2 ); |
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[8cb529e] | 400 | tick_preemption(); |
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[ea7d2b0] | 401 | unlock( event_kernel->lock ); |
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[8cb529e] | 402 | break; |
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[969b3fe] | 403 | // Signal was not sent by the kernel but by an other thread |
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[8cb529e] | 404 | case SI_QUEUE: |
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[969b3fe] | 405 | // For now, other thread only signal the alarm thread to shut it down |
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| 406 | // If this needs to change use info.si_value and handle the case here |
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[8cb529e] | 407 | goto EXIT; |
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[cd17862] | 408 | } |
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| 409 | } |
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[a0b3e32] | 410 | |
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[8cb529e] | 411 | EXIT: |
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[169d944] | 412 | __cfaabi_dbg_print_safe( "Kernel : Preemption thread stopping\n" ); |
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[a0b3e32] | 413 | return NULL; |
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[82ff5845] | 414 | } |
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| 415 | |
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[b68fc85] | 416 | //============================================================================================= |
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| 417 | // Kernel Signal Debug |
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| 418 | //============================================================================================= |
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| 419 | |
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| 420 | void __cfaabi_check_preemption() { |
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[14a61b5] | 421 | bool ready = kernelTLS.preemption_state.enabled; |
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[b68fc85] | 422 | if(!ready) { abort("Preemption should be ready"); } |
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| 423 | |
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| 424 | sigset_t oldset; |
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| 425 | int ret; |
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| 426 | ret = sigprocmask(0, NULL, &oldset); |
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| 427 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
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| 428 | |
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| 429 | ret = sigismember(&oldset, SIGUSR1); |
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| 430 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
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| 431 | |
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| 432 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
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| 433 | } |
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| 434 | |
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[6b0b624] | 435 | // Local Variables: // |
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| 436 | // mode: c // |
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| 437 | // tab-width: 4 // |
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| 438 | // End: // |
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