[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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[231b18f] | 12 | // Last Modified On : Fri Nov 6 07:42:13 2020 |
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| 13 | // Update Count : 54 |
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[c81ebf9] | 14 | // |
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| 15 | |
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[2026bb6] | 16 | #define __cforall_thread__ |
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[1c6e1ec] | 17 | // #define __CFA_DEBUG_PRINT_PREEMPTION__ |
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[2026bb6] | 18 | |
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[73abe95] | 19 | #include "preemption.hfa" |
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[c457dc41] | 20 | |
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[a83ffa4] | 21 | #include <assert.h> |
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[c81ebf9] | 22 | |
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[82ff5845] | 23 | #include <errno.h> |
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| 24 | #include <stdio.h> |
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| 25 | #include <string.h> |
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| 26 | #include <unistd.h> |
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[27f5f71] | 27 | #include <limits.h> // PTHREAD_STACK_MIN |
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[c81ebf9] | 28 | |
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[c457dc41] | 29 | #include "bits/debug.hfa" |
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[73abe95] | 30 | #include "bits/signal.hfa" |
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[e660761] | 31 | #include "kernel_private.hfa" |
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[82ff5845] | 32 | |
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[1c6e1ec] | 33 | |
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[d8548e2] | 34 | #if !defined(__CFA_DEFAULT_PREEMPTION__) |
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[2a84d06d] | 35 | #define __CFA_DEFAULT_PREEMPTION__ 10`ms |
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[d8548e2] | 36 | #endif |
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[c81ebf9] | 37 | |
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[1c6e1ec] | 38 | __attribute__((weak)) Duration default_preemption() { |
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[357fae8] | 39 | const char * preempt_rate_s = getenv("CFA_DEFAULT_PREEMPTION"); |
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[1c6e1ec] | 40 | if(!preempt_rate_s) { |
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[357fae8] | 41 | __cfadbg_print_safe(preemption, "No CFA_DEFAULT_PREEMPTION in ENV\n"); |
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[1c6e1ec] | 42 | return __CFA_DEFAULT_PREEMPTION__; |
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| 43 | } |
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| 44 | |
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| 45 | char * endptr = 0p; |
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| 46 | long int preempt_rate_l = strtol(preempt_rate_s, &endptr, 10); |
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| 47 | if(preempt_rate_l < 0 || preempt_rate_l > 65535) { |
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[357fae8] | 48 | __cfadbg_print_safe(preemption, "CFA_DEFAULT_PREEMPTION out of range : %ld\n", preempt_rate_l); |
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[1c6e1ec] | 49 | return __CFA_DEFAULT_PREEMPTION__; |
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| 50 | } |
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| 51 | if('\0' != *endptr) { |
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[357fae8] | 52 | __cfadbg_print_safe(preemption, "CFA_DEFAULT_PREEMPTION not a decimal number : %s\n", preempt_rate_s); |
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[1c6e1ec] | 53 | return __CFA_DEFAULT_PREEMPTION__; |
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| 54 | } |
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| 55 | |
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| 56 | return preempt_rate_l`ms; |
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[c81ebf9] | 57 | } |
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| 58 | |
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[969b3fe] | 59 | // FwdDeclarations : timeout handlers |
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[c81ebf9] | 60 | static void preempt( processor * this ); |
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[e873838] | 61 | static void timeout( $thread * this ); |
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[c81ebf9] | 62 | |
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[969b3fe] | 63 | // FwdDeclarations : Signal handlers |
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[c29c342] | 64 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ); |
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[c59a346] | 65 | static void sigHandler_alarm ( __CFA_SIGPARMS__ ); |
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[c29c342] | 66 | static void sigHandler_segv ( __CFA_SIGPARMS__ ); |
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| 67 | static void sigHandler_ill ( __CFA_SIGPARMS__ ); |
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| 68 | static void sigHandler_fpe ( __CFA_SIGPARMS__ ); |
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| 69 | static void sigHandler_abort ( __CFA_SIGPARMS__ ); |
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[82ff5845] | 70 | |
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[969b3fe] | 71 | // FwdDeclarations : alarm thread main |
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[c29c342] | 72 | static void * alarm_loop( __attribute__((unused)) void * args ); |
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[969b3fe] | 73 | |
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| 74 | // Machine specific register name |
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[381fdee] | 75 | #if defined( __i386 ) |
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[b2b44d8] | 76 | #define CFA_REG_IP gregs[REG_EIP] |
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[381fdee] | 77 | #elif defined( __x86_64 ) |
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| 78 | #define CFA_REG_IP gregs[REG_RIP] |
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[e9b49379] | 79 | #elif defined( __arm__ ) |
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| 80 | #define CFA_REG_IP arm_pc |
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| 81 | #elif defined( __aarch64__ ) |
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[482fa08] | 82 | #define CFA_REG_IP pc |
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[381fdee] | 83 | #else |
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[e9b49379] | 84 | #error unsupported hardware architecture |
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[cd17862] | 85 | #endif |
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| 86 | |
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[969b3fe] | 87 | KERNEL_STORAGE(event_kernel_t, event_kernel); // private storage for event kernel |
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| 88 | event_kernel_t * event_kernel; // kernel public handle to even kernel |
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| 89 | static pthread_t alarm_thread; // pthread handle to alarm thread |
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[09d4b22] | 90 | static void * alarm_stack; // pthread stack for alarm thread |
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[969b3fe] | 91 | |
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[c29c342] | 92 | static void ?{}(event_kernel_t & this) with( this ) { |
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[65deb18] | 93 | alarms{}; |
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| 94 | lock{}; |
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[969b3fe] | 95 | } |
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[82ff5845] | 96 | |
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[4dad189] | 97 | enum { |
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| 98 | PREEMPT_NORMAL = 0, |
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| 99 | PREEMPT_TERMINATE = 1, |
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| 100 | }; |
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| 101 | |
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[c81ebf9] | 102 | //============================================================================================= |
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| 103 | // Kernel Preemption logic |
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| 104 | //============================================================================================= |
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| 105 | |
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[969b3fe] | 106 | // Get next expired node |
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[2a84d06d] | 107 | static inline alarm_node_t * get_expired( alarm_list_t * alarms, Time currtime ) { |
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[d3ab183] | 108 | if( ! & (*alarms)`first ) return 0p; // If no alarms return null |
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[c457dc41] | 109 | if( (*alarms)`first.timeval >= currtime ) return 0p; // If alarms head not expired return null |
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[27f5f71] | 110 | return pop(alarms); // Otherwise just pop head |
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[969b3fe] | 111 | } |
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| 112 | |
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| 113 | // Tick one frame of the Discrete Event Simulation for alarms |
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[e873838] | 114 | static void tick_preemption(void) { |
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[27f5f71] | 115 | alarm_node_t * node = 0p; // Used in the while loop but cannot be declared in the while condition |
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| 116 | alarm_list_t * alarms = &event_kernel->alarms; // Local copy for ease of reading |
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| 117 | Time currtime = __kernel_get_time(); // Check current time once so everything "happens at once" |
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[8cb529e] | 118 | |
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[969b3fe] | 119 | //Loop throught every thing expired |
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| 120 | while( node = get_expired( alarms, currtime ) ) { |
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[c9ec301] | 121 | __cfadbg_print_buffer_decl( preemption, " KERNEL: preemption tick %lu\n", currtime.tn); |
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[185efe6] | 122 | Duration period = node->period; |
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| 123 | if( period == 0) { |
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| 124 | node->set = false; // Node is one-shot, just mark it as not pending |
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| 125 | } |
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[1c273d0] | 126 | |
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[c9ec301] | 127 | __cfadbg_print_buffer_local( preemption, " KERNEL: alarm ticking node %p.\n", node ); |
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| 128 | |
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| 129 | |
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[969b3fe] | 130 | // Check if this is a kernel |
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[4b30e8cc] | 131 | if( node->type == Kernel ) { |
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[c81ebf9] | 132 | preempt( node->proc ); |
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| 133 | } |
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[4b30e8cc] | 134 | else if( node->type == User ) { |
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[c9ec301] | 135 | __cfadbg_print_buffer_local( preemption, " KERNEL: alarm unparking %p.\n", node->thrd ); |
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[e873838] | 136 | timeout( node->thrd ); |
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[c81ebf9] | 137 | } |
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[4b30e8cc] | 138 | else { |
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[eeb5023] | 139 | node->callback(*node); |
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[4b30e8cc] | 140 | } |
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[c81ebf9] | 141 | |
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[969b3fe] | 142 | // Check if this is a periodic alarm |
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[8cb529e] | 143 | if( period > 0 ) { |
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[c9ec301] | 144 | __cfadbg_print_buffer_local( preemption, " KERNEL: alarm period is %lu.\n", period`ns ); |
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[c457dc41] | 145 | node->timeval = currtime + period; // Alarm is periodic, add currtime to it (used cached current time) |
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[969b3fe] | 146 | insert( alarms, node ); // Reinsert the node for the next time it triggers |
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[c81ebf9] | 147 | } |
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| 148 | } |
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| 149 | |
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[969b3fe] | 150 | // If there are still alarms pending, reset the timer |
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[d3ab183] | 151 | if( & (*alarms)`first ) { |
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[c457dc41] | 152 | Duration delta = (*alarms)`first.timeval - currtime; |
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| 153 | __kernel_set_timer( delta ); |
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[b1a4300] | 154 | } |
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[c81ebf9] | 155 | } |
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| 156 | |
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[969b3fe] | 157 | // Update the preemption of a processor and notify interested parties |
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[2a84d06d] | 158 | void update_preemption( processor * this, Duration duration ) { |
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[c81ebf9] | 159 | alarm_node_t * alarm = this->preemption_alarm; |
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| 160 | |
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| 161 | // Alarms need to be enabled |
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[2a84d06d] | 162 | if ( duration > 0 && ! alarm->set ) { |
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[c457dc41] | 163 | alarm->initial = duration; |
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| 164 | alarm->period = duration; |
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[c81ebf9] | 165 | register_self( alarm ); |
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| 166 | } |
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[8ad6533] | 167 | // Zero duration but alarm is set |
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[c81ebf9] | 168 | else if ( duration == 0 && alarm->set ) { |
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| 169 | unregister_self( alarm ); |
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[c457dc41] | 170 | alarm->initial = 0; |
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| 171 | alarm->period = 0; |
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[c81ebf9] | 172 | } |
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| 173 | // If alarm is different from previous, change it |
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| 174 | else if ( duration > 0 && alarm->period != duration ) { |
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| 175 | unregister_self( alarm ); |
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[c457dc41] | 176 | alarm->initial = duration; |
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| 177 | alarm->period = duration; |
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[c81ebf9] | 178 | register_self( alarm ); |
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| 179 | } |
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| 180 | } |
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| 181 | |
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| 182 | //============================================================================================= |
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[cd17862] | 183 | // Kernel Signal Tools |
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[c81ebf9] | 184 | //============================================================================================= |
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[231b18f] | 185 | // In a user-level threading system, there are handful of thread-local variables where this problem occurs on the ARM. |
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[54dcab1] | 186 | // |
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[231b18f] | 187 | // For each kernel thread running user-level threads, there is a flag variable to indicate if interrupts are |
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| 188 | // enabled/disabled for that kernel thread. Therefore, this variable is made thread local. |
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[54dcab1] | 189 | // |
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[231b18f] | 190 | // For example, this code fragment sets the state of the "interrupt" variable in thread-local memory. |
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[54dcab1] | 191 | // |
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[231b18f] | 192 | // _Thread_local volatile int interrupts; |
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| 193 | // int main() { |
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| 194 | // interrupts = 0; // disable interrupts } |
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[54dcab1] | 195 | // |
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[231b18f] | 196 | // which generates the following code on the ARM |
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[54dcab1] | 197 | // |
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[231b18f] | 198 | // (gdb) disassemble main |
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| 199 | // Dump of assembler code for function main: |
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| 200 | // 0x0000000000000610 <+0>: mrs x1, tpidr_el0 |
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| 201 | // 0x0000000000000614 <+4>: mov w0, #0x0 // #0 |
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| 202 | // 0x0000000000000618 <+8>: add x1, x1, #0x0, lsl #12 |
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| 203 | // 0x000000000000061c <+12>: add x1, x1, #0x10 |
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| 204 | // 0x0000000000000620 <+16>: str wzr, [x1] |
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| 205 | // 0x0000000000000624 <+20>: ret |
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[54dcab1] | 206 | // |
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[231b18f] | 207 | // The mrs moves a pointer from coprocessor register tpidr_el0 into register x1. Register w0 is set to 0. The two adds |
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| 208 | // increase the TLS pointer with the displacement (offset) 0x10, which is the location in the TSL of variable |
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| 209 | // "interrupts". Finally, 0 is stored into "interrupts" through the pointer in register x1 that points into the |
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| 210 | // TSL. Now once x1 has the pointer to the location of the TSL for kernel thread N, it can be be preempted at a |
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| 211 | // user-level and the user thread is put on the user-level ready-queue. When the preempted thread gets to the front of |
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| 212 | // the user-level ready-queue it is run on kernel thread M. It now stores 0 into "interrupts" back on kernel thread N, |
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| 213 | // turning off interrupt on the wrong kernel thread. |
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[54dcab1] | 214 | // |
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[231b18f] | 215 | // On the x86, the following code is generated for the same code fragment. |
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[54dcab1] | 216 | // |
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[231b18f] | 217 | // (gdb) disassemble main |
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| 218 | // Dump of assembler code for function main: |
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| 219 | // 0x0000000000400420 <+0>: movl $0x0,%fs:0xfffffffffffffffc |
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| 220 | // 0x000000000040042c <+12>: xor %eax,%eax |
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[54dcab1] | 221 | // 0x000000000040042e <+14>: retq |
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| 222 | // |
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[231b18f] | 223 | // and there is base-displacement addressing used to atomically reset variable "interrupts" off of the TSL pointer in |
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| 224 | // register "fs". |
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[54dcab1] | 225 | // |
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[231b18f] | 226 | // Hence, the ARM has base-displacement address for the general purpose registers, BUT not to the coprocessor |
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| 227 | // registers. As a result, generating the address for the write into variable "interrupts" is no longer atomic. |
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[54dcab1] | 228 | // |
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[231b18f] | 229 | // Note this problem does NOT occur when just using multiple kernel threads because the preemption ALWAYS restarts the |
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| 230 | // thread on the same kernel thread. |
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[54dcab1] | 231 | // |
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[231b18f] | 232 | // The obvious question is why does ARM use a coprocessor register to store the TSL pointer given that coprocessor |
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| 233 | // registers are second-class registers with respect to the instruction set. One possible answer is that they did not |
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| 234 | // want to dedicate one of the general registers to hold the TLS pointer and there was a free coprocessor register |
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| 235 | // available. |
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[c81ebf9] | 236 | |
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[ead174a] | 237 | //----------------------------------------------------------------------------- |
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| 238 | // Some assembly required |
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| 239 | #define __cfaasm_label(label, when) when: asm volatile goto(".global __cfaasm_" #label "_" #when "\n" "__cfaasm_" #label "_" #when ":":::"memory":when) |
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| 240 | |
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[8fc652e0] | 241 | //---------- |
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| 242 | // special case for preemption since used often |
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| 243 | bool __preemption_enabled() { |
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| 244 | // create a assembler label before |
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| 245 | // marked as clobber all to avoid movement |
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[ead174a] | 246 | __cfaasm_label(check, before); |
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[8fc652e0] | 247 | |
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| 248 | // access tls as normal |
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| 249 | bool enabled = __cfaabi_tls.preemption_state.enabled; |
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| 250 | |
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| 251 | // create a assembler label after |
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| 252 | // marked as clobber all to avoid movement |
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[ead174a] | 253 | __cfaasm_label(check, after); |
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[8fc652e0] | 254 | return enabled; |
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| 255 | } |
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| 256 | |
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[82a2fed] | 257 | struct asm_region { |
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| 258 | void * before; |
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| 259 | void * after; |
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| 260 | }; |
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| 261 | |
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| 262 | static inline bool __cfaasm_in( void * ip, struct asm_region & region ) { |
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| 263 | return ip >= region.before && ip <= region.after; |
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| 264 | } |
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| 265 | |
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| 266 | |
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[8fc652e0] | 267 | //---------- |
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| 268 | // Get data from the TLS block |
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[82a2fed] | 269 | // struct asm_region __cfaasm_get; |
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[8fc652e0] | 270 | uintptr_t __cfatls_get( unsigned long int offset ) __attribute__((__noinline__)); //no inline to avoid problems |
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| 271 | uintptr_t __cfatls_get( unsigned long int offset ) { |
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| 272 | // create a assembler label before |
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| 273 | // marked as clobber all to avoid movement |
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[ead174a] | 274 | __cfaasm_label(get, before); |
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[8fc652e0] | 275 | |
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| 276 | // access tls as normal (except for pointer arithmetic) |
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| 277 | uintptr_t val = *(uintptr_t*)((uintptr_t)&__cfaabi_tls + offset); |
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| 278 | |
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| 279 | // create a assembler label after |
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| 280 | // marked as clobber all to avoid movement |
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[ead174a] | 281 | __cfaasm_label(get, after); |
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[8fc652e0] | 282 | return val; |
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| 283 | } |
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| 284 | |
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[82ff5845] | 285 | extern "C" { |
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[969b3fe] | 286 | // Disable interrupts by incrementing the counter |
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[82ff5845] | 287 | void disable_interrupts() { |
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[8fc652e0] | 288 | // create a assembler label before |
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| 289 | // marked as clobber all to avoid movement |
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[ead174a] | 290 | __cfaasm_label(dsable, before); |
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[8fc652e0] | 291 | |
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| 292 | with( __cfaabi_tls.preemption_state ) { |
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[1f81d61] | 293 | #if GCC_VERSION > 50000 |
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[13073be] | 294 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
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[1f81d61] | 295 | #endif |
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[13073be] | 296 | |
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| 297 | // Set enabled flag to false |
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| 298 | // should be atomic to avoid preemption in the middle of the operation. |
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| 299 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
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| 300 | __atomic_store_n(&enabled, false, __ATOMIC_RELAXED); |
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| 301 | |
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| 302 | // Signal the compiler that a fence is needed but only for signal handlers |
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| 303 | __atomic_signal_fence(__ATOMIC_ACQUIRE); |
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| 304 | |
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[de6319f] | 305 | __attribute__((unused)) unsigned short new_val = disable_count + 1; |
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| 306 | disable_count = new_val; |
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| 307 | verify( new_val < 65_000u ); // If this triggers someone is disabling interrupts without enabling them |
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| 308 | } |
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[8fc652e0] | 309 | |
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| 310 | // create a assembler label after |
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| 311 | // marked as clobber all to avoid movement |
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[ead174a] | 312 | __cfaasm_label(dsable, after); |
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| 313 | |
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[82ff5845] | 314 | } |
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| 315 | |
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[969b3fe] | 316 | // Enable interrupts by decrementing the counter |
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[c7a900a] | 317 | // If counter reaches 0, execute any pending __cfactx_switch |
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[a3821fa] | 318 | void enable_interrupts( bool poll ) { |
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[ead174a] | 319 | // Cache the processor now since interrupts can start happening after the atomic store |
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| 320 | processor * proc = __cfaabi_tls.this_processor; |
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[a3821fa] | 321 | /* paranoid */ verify( !poll || proc ); |
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[969b3fe] | 322 | |
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[8fc652e0] | 323 | with( __cfaabi_tls.preemption_state ){ |
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[de6319f] | 324 | unsigned short prev = disable_count; |
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| 325 | disable_count -= 1; |
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[ead174a] | 326 | |
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| 327 | // If this triggers someone is enabled already enabled interruptsverify( prev != 0u ); |
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| 328 | /* paranoid */ verify( prev != 0u ); |
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[de6319f] | 329 | |
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| 330 | // Check if we need to prempt the thread because an interrupt was missed |
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| 331 | if( prev == 1 ) { |
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[1f81d61] | 332 | #if GCC_VERSION > 50000 |
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[ead174a] | 333 | static_assert(__atomic_always_lock_free(sizeof(enabled), &enabled), "Must be lock-free"); |
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[1f81d61] | 334 | #endif |
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[13073be] | 335 | |
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| 336 | // Set enabled flag to true |
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| 337 | // should be atomic to avoid preemption in the middle of the operation. |
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| 338 | // use memory order RELAXED since there is no inter-thread on this variable requirements |
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| 339 | __atomic_store_n(&enabled, true, __ATOMIC_RELAXED); |
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| 340 | |
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| 341 | // Signal the compiler that a fence is needed but only for signal handlers |
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| 342 | __atomic_signal_fence(__ATOMIC_RELEASE); |
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[a3821fa] | 343 | if( poll && proc->pending_preemption ) { |
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[de6319f] | 344 | proc->pending_preemption = false; |
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[3381ed7] | 345 | force_yield( __POLL_PREEMPTION ); |
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[de6319f] | 346 | } |
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[d0a045c7] | 347 | } |
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[82ff5845] | 348 | } |
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[969b3fe] | 349 | } |
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[82ff5845] | 350 | } |
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| 351 | |
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[adf34b3] | 352 | //----------------------------------------------------------------------------- |
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| 353 | // Kernel Signal Debug |
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| 354 | void __cfaabi_check_preemption() { |
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| 355 | bool ready = __preemption_enabled(); |
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| 356 | if(!ready) { abort("Preemption should be ready"); } |
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| 357 | |
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| 358 | __cfaasm_label(debug, before); |
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| 359 | |
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| 360 | sigset_t oldset; |
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| 361 | int ret; |
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| 362 | ret = pthread_sigmask(0, ( const sigset_t * ) 0p, &oldset); // workaround trac#208: cast should be unnecessary |
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| 363 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
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| 364 | |
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| 365 | ret = sigismember(&oldset, SIGUSR1); |
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| 366 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
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| 367 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
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| 368 | |
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| 369 | ret = sigismember(&oldset, SIGALRM); |
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| 370 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
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| 371 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
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| 372 | |
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| 373 | ret = sigismember(&oldset, SIGTERM); |
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| 374 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
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| 375 | if(ret == 1) { abort("ERROR SIGTERM is disabled"); } |
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| 376 | |
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| 377 | __cfaasm_label(debug, after); |
---|
| 378 | } |
---|
| 379 | |
---|
| 380 | #ifdef __CFA_WITH_VERIFY__ |
---|
| 381 | bool __cfaabi_dbg_in_kernel() { |
---|
| 382 | return !__preemption_enabled(); |
---|
| 383 | } |
---|
| 384 | #endif |
---|
| 385 | |
---|
[ead174a] | 386 | #undef __cfaasm_label |
---|
| 387 | |
---|
[adf34b3] | 388 | //----------------------------------------------------------------------------- |
---|
| 389 | // Signal handling |
---|
| 390 | |
---|
[969b3fe] | 391 | // sigprocmask wrapper : unblock a single signal |
---|
[7222630] | 392 | static inline void signal_unblock( int sig ) { |
---|
[82ff5845] | 393 | sigset_t mask; |
---|
| 394 | sigemptyset( &mask ); |
---|
[1c273d0] | 395 | sigaddset( &mask, sig ); |
---|
[82ff5845] | 396 | |
---|
[27f5f71] | 397 | if ( pthread_sigmask( SIG_UNBLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 398 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 399 | } |
---|
[82ff5845] | 400 | } |
---|
| 401 | |
---|
[969b3fe] | 402 | // sigprocmask wrapper : block a single signal |
---|
[7222630] | 403 | static inline void signal_block( int sig ) { |
---|
[cd17862] | 404 | sigset_t mask; |
---|
| 405 | sigemptyset( &mask ); |
---|
| 406 | sigaddset( &mask, sig ); |
---|
[47ecf2b] | 407 | |
---|
[27f5f71] | 408 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[c59a346] | 409 | abort( "internal error, pthread_sigmask" ); |
---|
[cd17862] | 410 | } |
---|
| 411 | } |
---|
[47ecf2b] | 412 | |
---|
[969b3fe] | 413 | // kill wrapper : signal a processor |
---|
[cd17862] | 414 | static void preempt( processor * this ) { |
---|
[4dad189] | 415 | sigval_t value = { PREEMPT_NORMAL }; |
---|
| 416 | pthread_sigqueue( this->kernel_thread, SIGUSR1, value ); |
---|
| 417 | } |
---|
| 418 | |
---|
[969b3fe] | 419 | // reserved for future use |
---|
[e873838] | 420 | static void timeout( $thread * this ) { |
---|
| 421 | unpark( this ); |
---|
[cd17862] | 422 | } |
---|
| 423 | |
---|
[7222630] | 424 | void __disable_interrupts_hard() { |
---|
| 425 | sigset_t oldset; |
---|
| 426 | int ret; |
---|
| 427 | ret = pthread_sigmask(0, ( const sigset_t * ) 0p, &oldset); // workaround trac#208: cast should be unnecessary |
---|
| 428 | if(ret != 0) { abort("ERROR sigprocmask returned %d", ret); } |
---|
| 429 | |
---|
| 430 | ret = sigismember(&oldset, SIGUSR1); |
---|
| 431 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 432 | if(ret == 1) { abort("ERROR SIGUSR1 is disabled"); } |
---|
| 433 | |
---|
| 434 | ret = sigismember(&oldset, SIGALRM); |
---|
| 435 | if(ret < 0) { abort("ERROR sigismember returned %d", ret); } |
---|
| 436 | if(ret == 0) { abort("ERROR SIGALRM is enabled"); } |
---|
| 437 | |
---|
| 438 | signal_block( SIGUSR1 ); |
---|
| 439 | } |
---|
| 440 | |
---|
| 441 | void __enable_interrupts_hard() { |
---|
| 442 | signal_unblock( SIGUSR1 ); |
---|
| 443 | |
---|
| 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 | |
---|
[82a2fed] | 458 | //----------------------------------------------------------------------------- |
---|
| 459 | // Some assembly required |
---|
| 460 | #if defined( __i386 ) |
---|
| 461 | #ifdef __PIC__ |
---|
| 462 | #define RELOC_PRELUDE( label ) \ |
---|
| 463 | "calll .Lcfaasm_prelude_" #label "$pb\n\t" \ |
---|
| 464 | ".Lcfaasm_prelude_" #label "$pb:\n\t" \ |
---|
| 465 | "popl %%eax\n\t" \ |
---|
| 466 | ".Lcfaasm_prelude_" #label "_end:\n\t" \ |
---|
| 467 | "addl $_GLOBAL_OFFSET_TABLE_+(.Lcfaasm_prelude_" #label "_end-.Lcfaasm_prelude_" #label "$pb), %%eax\n\t" |
---|
| 468 | #define RELOC_PREFIX "" |
---|
| 469 | #define RELOC_SUFFIX "@GOT(%%eax)" |
---|
| 470 | #else |
---|
| 471 | #define RELOC_PREFIX "$" |
---|
| 472 | #define RELOC_SUFFIX "" |
---|
| 473 | #endif |
---|
[a12810d] | 474 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 475 | ({ \ |
---|
| 476 | struct asm_region region; \ |
---|
| 477 | asm( \ |
---|
| 478 | RELOC_PRELUDE( label ) \ |
---|
| 479 | "movl " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \ |
---|
| 480 | "movl " RELOC_PREFIX "__cfaasm_" #label "_after" RELOC_SUFFIX ", %[va]\n\t" \ |
---|
| 481 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 482 | ); \ |
---|
| 483 | region; \ |
---|
| 484 | }); |
---|
| 485 | #elif defined( __x86_64 ) |
---|
| 486 | #ifdef __PIC__ |
---|
| 487 | #define RELOC_PREFIX "" |
---|
| 488 | #define RELOC_SUFFIX "@GOTPCREL(%%rip)" |
---|
| 489 | #else |
---|
| 490 | #define RELOC_PREFIX "$" |
---|
| 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 | "movq " RELOC_PREFIX "__cfaasm_" #label "_before" RELOC_SUFFIX ", %[vb]\n\t" \ |
---|
| 498 | "movq " RELOC_PREFIX "__cfaasm_" #label "_after" RELOC_SUFFIX ", %[va]\n\t" \ |
---|
| 499 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 500 | ); \ |
---|
| 501 | region; \ |
---|
| 502 | }); |
---|
| 503 | #elif defined( __aarch64__ ) |
---|
| 504 | #ifdef __PIC__ |
---|
[ead174a] | 505 | // Note that this works only for gcc |
---|
[a12810d] | 506 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 507 | ({ \ |
---|
| 508 | struct asm_region region; \ |
---|
| 509 | asm( \ |
---|
[ead174a] | 510 | "adrp %[vb], _GLOBAL_OFFSET_TABLE_" "\n\t" \ |
---|
| 511 | "ldr %[vb], [%[vb], #:gotpage_lo15:__cfaasm_" #label "_before]" "\n\t" \ |
---|
| 512 | "adrp %[va], _GLOBAL_OFFSET_TABLE_" "\n\t" \ |
---|
| 513 | "ldr %[va], [%[va], #:gotpage_lo15:__cfaasm_" #label "_after]" "\n\t" \ |
---|
[82a2fed] | 514 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 515 | ); \ |
---|
| 516 | region; \ |
---|
| 517 | }); |
---|
| 518 | #else |
---|
[ead174a] | 519 | #error this is not the right thing to do |
---|
[b5344a3] | 520 | /* |
---|
[a12810d] | 521 | #define __cfaasm_label( label ) struct asm_region label = \ |
---|
[82a2fed] | 522 | ({ \ |
---|
| 523 | struct asm_region region; \ |
---|
| 524 | asm( \ |
---|
[b5344a3] | 525 | "adrp %[vb], __cfaasm_" #label "_before" "\n\t" \ |
---|
| 526 | "add %[vb], %[vb], :lo12:__cfaasm_" #label "_before" "\n\t" \ |
---|
| 527 | "adrp %[va], :got:__cfaasm_" #label "_after" "\n\t" \ |
---|
| 528 | "add %[va], %[va], :lo12:__cfaasm_" #label "_after" "\n\t" \ |
---|
[82a2fed] | 529 | : [vb]"=r"(region.before), [va]"=r"(region.after) \ |
---|
| 530 | ); \ |
---|
| 531 | region; \ |
---|
| 532 | }); |
---|
[b5344a3] | 533 | */ |
---|
[ead174a] | 534 | #endif |
---|
[82a2fed] | 535 | #else |
---|
| 536 | #error unknown hardware architecture |
---|
| 537 | #endif |
---|
| 538 | |
---|
[14a61b5] | 539 | // KERNEL ONLY |
---|
[c7a900a] | 540 | // Check if a __cfactx_switch signal handler shoud defer |
---|
[969b3fe] | 541 | // If true : preemption is safe |
---|
| 542 | // If false : preemption is unsafe and marked as pending |
---|
[82a2fed] | 543 | static inline bool preemption_ready( void * ip ) { |
---|
| 544 | // Get all the region for which it is not safe to preempt |
---|
| 545 | __cfaasm_label( get ); |
---|
| 546 | __cfaasm_label( check ); |
---|
| 547 | __cfaasm_label( dsable ); |
---|
[adf34b3] | 548 | __cfaasm_label( debug ); |
---|
[14a61b5] | 549 | |
---|
[82a2fed] | 550 | // Check if preemption is safe |
---|
| 551 | bool ready = true; |
---|
| 552 | if( __cfaasm_in( ip, get ) ) { ready = false; goto EXIT; }; |
---|
| 553 | if( __cfaasm_in( ip, check ) ) { ready = false; goto EXIT; }; |
---|
| 554 | if( __cfaasm_in( ip, dsable ) ) { ready = false; goto EXIT; }; |
---|
[adf34b3] | 555 | if( __cfaasm_in( ip, debug ) ) { ready = false; goto EXIT; }; |
---|
[82a2fed] | 556 | if( !__cfaabi_tls.preemption_state.enabled) { ready = false; goto EXIT; }; |
---|
| 557 | if( __cfaabi_tls.preemption_state.in_progress ) { ready = false; goto EXIT; }; |
---|
| 558 | |
---|
| 559 | EXIT: |
---|
[14a61b5] | 560 | // Adjust the pending flag accordingly |
---|
[8fc652e0] | 561 | __cfaabi_tls.this_processor->pending_preemption = !ready; |
---|
[969b3fe] | 562 | return ready; |
---|
| 563 | } |
---|
| 564 | |
---|
[cd17862] | 565 | //============================================================================================= |
---|
| 566 | // Kernel Signal Startup/Shutdown logic |
---|
| 567 | //============================================================================================= |
---|
| 568 | |
---|
[969b3fe] | 569 | // Startup routine to activate preemption |
---|
| 570 | // Called from kernel_startup |
---|
[e660761] | 571 | void __kernel_alarm_startup() { |
---|
[169d944] | 572 | __cfaabi_dbg_print_safe( "Kernel : Starting preemption\n" ); |
---|
[969b3fe] | 573 | |
---|
| 574 | // Start with preemption disabled until ready |
---|
[8fc652e0] | 575 | __cfaabi_tls.preemption_state.enabled = false; |
---|
| 576 | __cfaabi_tls.preemption_state.disable_count = 1; |
---|
[969b3fe] | 577 | |
---|
| 578 | // Initialize the event kernel |
---|
| 579 | event_kernel = (event_kernel_t *)&storage_event_kernel; |
---|
[9236060] | 580 | (*event_kernel){}; |
---|
[969b3fe] | 581 | |
---|
| 582 | // Setup proper signal handlers |
---|
[6047b00] | 583 | __cfaabi_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO ); // __cfactx_switch handler |
---|
| 584 | __cfaabi_sigaction( SIGALRM, sigHandler_alarm , SA_SIGINFO ); // debug handler |
---|
[cd17862] | 585 | |
---|
| 586 | signal_block( SIGALRM ); |
---|
| 587 | |
---|
[8c50aed] | 588 | alarm_stack = __create_pthread( &alarm_thread, alarm_loop, 0p ); |
---|
[cd17862] | 589 | } |
---|
| 590 | |
---|
[969b3fe] | 591 | // Shutdown routine to deactivate preemption |
---|
| 592 | // Called from kernel_shutdown |
---|
[e660761] | 593 | void __kernel_alarm_shutdown() { |
---|
[169d944] | 594 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopping\n" ); |
---|
[d6ff3ff] | 595 | |
---|
[969b3fe] | 596 | // Block all signals since we are already shutting down |
---|
[cd17862] | 597 | sigset_t mask; |
---|
| 598 | sigfillset( &mask ); |
---|
[27f5f71] | 599 | sigprocmask( SIG_BLOCK, &mask, 0p ); |
---|
[cd17862] | 600 | |
---|
[969b3fe] | 601 | // Notify the alarm thread of the shutdown |
---|
[c457dc41] | 602 | sigval val; |
---|
| 603 | val.sival_int = 0; |
---|
[a0b3e32] | 604 | pthread_sigqueue( alarm_thread, SIGALRM, val ); |
---|
[969b3fe] | 605 | |
---|
| 606 | // Wait for the preemption thread to finish |
---|
[27f5f71] | 607 | |
---|
[bfcf6b9] | 608 | __destroy_pthread( alarm_thread, alarm_stack, 0p ); |
---|
[969b3fe] | 609 | |
---|
| 610 | // Preemption is now fully stopped |
---|
| 611 | |
---|
[169d944] | 612 | __cfaabi_dbg_print_safe( "Kernel : Preemption stopped\n" ); |
---|
[cd17862] | 613 | } |
---|
| 614 | |
---|
[92bfda0] | 615 | // Prevent preemption since we are about to start terminating things |
---|
| 616 | void __kernel_abort_lock(void) { |
---|
| 617 | signal_block( SIGUSR1 ); |
---|
| 618 | } |
---|
| 619 | |
---|
[969b3fe] | 620 | // Raii ctor/dtor for the preemption_scope |
---|
| 621 | // Used by thread to control when they want to receive preemption signals |
---|
[242a902] | 622 | void ?{}( preemption_scope & this, processor * proc ) { |
---|
[c457dc41] | 623 | (this.alarm){ proc, 0`s, 0`s }; |
---|
[242a902] | 624 | this.proc = proc; |
---|
| 625 | this.proc->preemption_alarm = &this.alarm; |
---|
[969b3fe] | 626 | |
---|
[d8548e2] | 627 | update_preemption( this.proc, this.proc->cltr->preemption_rate ); |
---|
[cd17862] | 628 | } |
---|
| 629 | |
---|
[242a902] | 630 | void ^?{}( preemption_scope & this ) { |
---|
[cd17862] | 631 | disable_interrupts(); |
---|
| 632 | |
---|
[2a84d06d] | 633 | update_preemption( this.proc, 0`s ); |
---|
[cd17862] | 634 | } |
---|
| 635 | |
---|
| 636 | //============================================================================================= |
---|
| 637 | // Kernel Signal Handlers |
---|
| 638 | //============================================================================================= |
---|
[54dcab1] | 639 | __cfaabi_dbg_debug_do( static thread_local void * last_interrupt = 0; ) |
---|
[47ecf2b] | 640 | |
---|
[969b3fe] | 641 | // Context switch signal handler |
---|
| 642 | // Receives SIGUSR1 signal and causes the current thread to yield |
---|
[c29c342] | 643 | static void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) { |
---|
[8fc652e0] | 644 | void * ip = (void *)(cxt->uc_mcontext.CFA_REG_IP); |
---|
| 645 | __cfaabi_dbg_debug_do( last_interrupt = ip; ) |
---|
[969b3fe] | 646 | |
---|
[4dad189] | 647 | // SKULLDUGGERY: if a thread creates a processor and the immediately deletes it, |
---|
| 648 | // the interrupt that is supposed to force the kernel thread to preempt might arrive |
---|
[482fa08] | 649 | // before the kernel thread has even started running. When that happens, an interrupt |
---|
[97cba9f] | 650 | // with a null 'this_processor' will be caught, just ignore it. |
---|
[8fc652e0] | 651 | if(! __cfaabi_tls.this_processor ) return; |
---|
[4dad189] | 652 | |
---|
| 653 | choose(sfp->si_value.sival_int) { |
---|
| 654 | case PREEMPT_NORMAL : ;// Normal case, nothing to do here |
---|
[8fc652e0] | 655 | case PREEMPT_TERMINATE: verify( __atomic_load_n( &__cfaabi_tls.this_processor->do_terminate, __ATOMIC_SEQ_CST ) ); |
---|
[4dad189] | 656 | default: |
---|
[ff878b7] | 657 | abort( "internal error, signal value is %d", sfp->si_value.sival_int ); |
---|
[4dad189] | 658 | } |
---|
| 659 | |
---|
[b2b44d8] | 660 | // Check if it is safe to preempt here |
---|
[82a2fed] | 661 | if( !preemption_ready( ip ) ) { return; } |
---|
[8fc652e0] | 662 | |
---|
| 663 | __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] | 664 | |
---|
| 665 | // Sync flag : prevent recursive calls to the signal handler |
---|
[8fc652e0] | 666 | __cfaabi_tls.preemption_state.in_progress = true; |
---|
[14a61b5] | 667 | |
---|
[a83ffa4] | 668 | // Clear sighandler mask before context switching. |
---|
[1f81d61] | 669 | #if GCC_VERSION > 50000 |
---|
[a83ffa4] | 670 | static_assert( sizeof( sigset_t ) == sizeof( cxt->uc_sigmask ), "Expected cxt->uc_sigmask to be of sigset_t" ); |
---|
[1f81d61] | 671 | #endif |
---|
[27f5f71] | 672 | if ( pthread_sigmask( SIG_SETMASK, (sigset_t *)&(cxt->uc_sigmask), 0p ) == -1 ) { |
---|
[a83ffa4] | 673 | abort( "internal error, sigprocmask" ); |
---|
| 674 | } |
---|
[05615ba] | 675 | |
---|
[14a61b5] | 676 | // Clear the in progress flag |
---|
[8fc652e0] | 677 | __cfaabi_tls.preemption_state.in_progress = false; |
---|
[969b3fe] | 678 | |
---|
| 679 | // Preemption can occur here |
---|
| 680 | |
---|
[c7a900a] | 681 | force_yield( __ALARM_PREEMPTION ); // Do the actual __cfactx_switch |
---|
[c81ebf9] | 682 | } |
---|
| 683 | |
---|
[c59a346] | 684 | static void sigHandler_alarm( __CFA_SIGPARMS__ ) { |
---|
| 685 | abort("SIGALRM should never reach the signal handler"); |
---|
[c81ebf9] | 686 | } |
---|
| 687 | |
---|
[969b3fe] | 688 | // Main of the alarm thread |
---|
| 689 | // Waits on SIGALRM and send SIGUSR1 to whom ever needs it |
---|
[c29c342] | 690 | static void * alarm_loop( __attribute__((unused)) void * args ) { |
---|
[c993b15] | 691 | unsigned id = register_proc_id(); |
---|
[1b033b8] | 692 | |
---|
[969b3fe] | 693 | // Block sigalrms to control when they arrive |
---|
[cd17862] | 694 | sigset_t mask; |
---|
[ade5272] | 695 | sigfillset(&mask); |
---|
[27f5f71] | 696 | if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) { |
---|
[169d944] | 697 | abort( "internal error, pthread_sigmask" ); |
---|
[82ff5845] | 698 | } |
---|
[c81ebf9] | 699 | |
---|
[ade5272] | 700 | sigemptyset( &mask ); |
---|
| 701 | sigaddset( &mask, SIGALRM ); |
---|
| 702 | |
---|
[969b3fe] | 703 | // Main loop |
---|
[cd17862] | 704 | while( true ) { |
---|
[969b3fe] | 705 | // Wait for a sigalrm |
---|
[a0b3e32] | 706 | siginfo_t info; |
---|
| 707 | int sig = sigwaitinfo( &mask, &info ); |
---|
[969b3fe] | 708 | |
---|
[c457dc41] | 709 | __cfadbg_print_buffer_decl ( preemption, " KERNEL: sigwaitinfo returned %d, c: %d, v: %d\n", sig, info.si_code, info.si_value.sival_int ); |
---|
| 710 | __cfadbg_print_buffer_local( preemption, " KERNEL: SI_QUEUE %d, SI_TIMER %d, SI_KERNEL %d\n", SI_QUEUE, SI_TIMER, SI_KERNEL ); |
---|
| 711 | |
---|
[e2f7bc3] | 712 | if( sig < 0 ) { |
---|
| 713 | //Error! |
---|
| 714 | int err = errno; |
---|
| 715 | switch( err ) { |
---|
| 716 | case EAGAIN : |
---|
| 717 | case EINTR : |
---|
[c457dc41] | 718 | {__cfadbg_print_buffer_local( preemption, " KERNEL: Spurious wakeup %d.\n", err );} |
---|
[e2f7bc3] | 719 | continue; |
---|
[27f5f71] | 720 | case EINVAL : |
---|
[169d944] | 721 | abort( "Timeout was invalid." ); |
---|
[e2f7bc3] | 722 | default: |
---|
[169d944] | 723 | abort( "Unhandled error %d", err); |
---|
[e2f7bc3] | 724 | } |
---|
| 725 | } |
---|
| 726 | |
---|
[969b3fe] | 727 | // If another signal arrived something went wrong |
---|
[8cb529e] | 728 | assertf(sig == SIGALRM, "Kernel Internal Error, sigwait: Unexpected signal %d (%d : %d)\n", sig, info.si_code, info.si_value.sival_int); |
---|
| 729 | |
---|
[969b3fe] | 730 | // Switch on the code (a.k.a. the sender) to |
---|
[8cb529e] | 731 | switch( info.si_code ) |
---|
[a0b3e32] | 732 | { |
---|
[c457dc41] | 733 | // Signal was not sent by the kernel but by an other thread |
---|
| 734 | case SI_QUEUE: |
---|
| 735 | // other threads may signal the alarm thread to shut it down |
---|
| 736 | // or to manual cause the preemption tick |
---|
| 737 | // use info.si_value and handle the case here |
---|
| 738 | switch( info.si_value.sival_int ) { |
---|
| 739 | case 0: |
---|
| 740 | goto EXIT; |
---|
| 741 | default: |
---|
| 742 | abort( "SI_QUEUE with val %d", info.si_value.sival_int); |
---|
| 743 | } |
---|
| 744 | // fallthrough |
---|
[969b3fe] | 745 | // Timers can apparently be marked as sent for the kernel |
---|
| 746 | // In either case, tick preemption |
---|
[8cb529e] | 747 | case SI_TIMER: |
---|
| 748 | case SI_KERNEL: |
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[169d944] | 749 | // __cfaabi_dbg_print_safe( "Kernel : Preemption thread tick\n" ); |
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[36982fc] | 750 | lock( event_kernel->lock __cfaabi_dbg_ctx2 ); |
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[e873838] | 751 | tick_preemption(); |
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[ea7d2b0] | 752 | unlock( event_kernel->lock ); |
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[8cb529e] | 753 | break; |
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[cd17862] | 754 | } |
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| 755 | } |
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[a0b3e32] | 756 | |
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[8cb529e] | 757 | EXIT: |
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[169d944] | 758 | __cfaabi_dbg_print_safe( "Kernel : Preemption thread stopping\n" ); |
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[c993b15] | 759 | unregister_proc_id(id); |
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[1b033b8] | 760 | |
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[27f5f71] | 761 | return 0p; |
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[82ff5845] | 762 | } |
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| 763 | |
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[6b0b624] | 764 | // Local Variables: // |
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| 765 | // mode: c // |
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| 766 | // tab-width: 4 // |
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| 767 | // End: // |
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