ast.h
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CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 45 * 46 * Carnegie Mellon requests users of this software to return to 47 * 48 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 49 * School of Computer Science 50 * Carnegie Mellon University 51 * Pittsburgh PA 15213-3890 52 * 53 * any improvements or extensions that they make and grant Carnegie Mellon 54 * the rights to redistribute these changes. 55 */ 56 /* 57 */ 58 59 /* 60 * kern/ast.h: Definitions for Asynchronous System Traps. 61 */ 62 63 #ifndef _KERN_AST_H_ 64 #define _KERN_AST_H_ 65 66 67 #include <kern/assert.h> 68 #include <kern/macro_help.h> 69 #include <kern/spl.h> 70 71 /* 72 * A processor detects an AST when it is about to return from an 73 * interrupt context, and calls ast_taken_kernel or ast_taken_user 74 * depending on whether it was returning from userspace or kernelspace. 75 * 76 * Machine-dependent code is responsible for maintaining 77 * a set of reasons for an AST. 78 */ 79 typedef uint32_t ast_t; 80 81 /* 82 * When returning from interrupt/trap context to kernel mode, 83 * if AST_URGENT is set, then ast_taken_kernel is called, for 84 * instance to effect preemption of a kernel thread by a realtime 85 * thread. 86 * 87 * This is also done when re-enabling preemption or re-enabling 88 * interrupts, since an AST may have been set while preemption 89 * was disabled, and it should take effect as soon as possible. 90 * 91 * When returning from interrupt/trap/syscall context to user 92 * mode, any and all ASTs that are pending should be handled by 93 * calling ast_taken_user. 94 * 95 * If a thread context switches, only ASTs not in AST_PER_THREAD 96 * remain active. The per-thread ASTs are stored in the thread_t 97 * and re-enabled when the thread context switches back. 98 * 99 * Typically the preemption ASTs are set as a result of threads 100 * becoming runnable, threads changing priority, or quantum 101 * expiration. If a thread becomes runnable and is chosen 102 * to run on another processor, cause_ast_check() may be called 103 * to IPI that processor and request csw_check() be run there. 104 */ 105 106 /* 107 * Bits for reasons 108 * TODO: Split the context switch and return-to-user AST namespaces 109 * NOTE: Some of these are exported as the 'reason' code in scheduler tracepoints 110 */ 111 #define AST_PREEMPT 0x01 112 #define AST_QUANTUM 0x02 113 #define AST_URGENT 0x04 114 #define AST_HANDOFF 0x08 115 #define AST_YIELD 0x10 116 #define AST_APC 0x20 /* migration APC hook */ 117 #define AST_LEDGER 0x40 118 #define AST_BSD 0x80 119 #define AST_KPERF 0x100 /* kernel profiling */ 120 #define AST_MACF 0x200 /* MACF user ret pending */ 121 #define AST_RESET_PCS 0x400 /* restartable ranges */ 122 #define AST_ARCADE 0x800 /* arcade subsciption support */ 123 #define AST_GUARD 0x1000 124 #define AST_TELEMETRY_USER 0x2000 /* telemetry sample requested on interrupt from userspace */ 125 #define AST_TELEMETRY_KERNEL 0x4000 /* telemetry sample requested on interrupt from kernel */ 126 #define AST_TELEMETRY_PMI 0x8000 /* telemetry sample requested on PMI */ 127 #define AST_SFI 0x10000 /* Evaluate if SFI wait is needed before return to userspace */ 128 #define AST_DTRACE 0x20000 129 #define AST_TELEMETRY_IO 0x40000 /* telemetry sample requested for I/O */ 130 #define AST_KEVENT 0x80000 131 #define AST_REBALANCE 0x100000 /* thread context switched due to rebalancing */ 132 #define AST_UNQUIESCE 0x200000 /* catch unquiesced processor before returning to userspace */ 133 134 #define AST_NONE 0x00 135 #define AST_ALL (~AST_NONE) 136 137 #define AST_SCHEDULING (AST_PREEMPTION | AST_YIELD | AST_HANDOFF) 138 #define AST_PREEMPTION (AST_PREEMPT | AST_QUANTUM | AST_URGENT) 139 140 #define AST_TELEMETRY_ALL (AST_TELEMETRY_USER | AST_TELEMETRY_KERNEL | \ 141 AST_TELEMETRY_PMI | AST_TELEMETRY_IO) 142 143 /* Per-thread ASTs follow the thread at context-switch time. */ 144 #define AST_PER_THREAD (AST_APC | AST_BSD | AST_MACF | AST_RESET_PCS | \ 145 AST_ARCADE | AST_LEDGER | AST_GUARD | AST_TELEMETRY_ALL | AST_KEVENT) 146 147 /* Handle AST_URGENT detected while in the kernel */ 148 extern void ast_taken_kernel(void); 149 150 /* Handle an AST flag set while returning to user mode (may continue via thread_exception_return) */ 151 extern void ast_taken_user(void); 152 153 /* Check for pending ASTs */ 154 extern void ast_check(processor_t processor); 155 156 /* Pending ast mask for the current processor */ 157 extern ast_t *ast_pending(void); 158 159 /* Set AST flags on current processor */ 160 extern void ast_on(ast_t reasons); 161 162 /* Clear AST flags on current processor */ 163 extern void ast_off(ast_t reasons); 164 165 /* Consume specified AST flags from current processor */ 166 extern ast_t ast_consume(ast_t reasons); 167 168 /* Read specified AST flags from current processor */ 169 extern ast_t ast_peek(ast_t reasons); 170 171 /* Re-set current processor's per-thread AST flags to those set on thread */ 172 extern void ast_context(thread_t thread); 173 174 /* Propagate ASTs set on a thread to the current processor */ 175 extern void ast_propagate(thread_t thread); 176 177 /* 178 * Set an AST on a thread with thread_ast_set. 179 * 180 * You can then propagate it to the current processor with ast_propagate(), 181 * or tell another processor to act on it with cause_ast_check(). 182 * 183 * See act_set_ast() for an example. 184 */ 185 #define thread_ast_set(act, reason) ((void)os_atomic_or(&(act)->ast, (reason), relaxed)) 186 #define thread_ast_clear(act, reason) ((void)os_atomic_andnot(&(act)->ast, (reason), relaxed)) 187 188 #ifdef MACH_BSD 189 190 extern void act_set_astbsd(thread_t); 191 extern void bsd_ast(thread_t); 192 193 #endif /* MACH_BSD */ 194 195 #ifdef CONFIG_DTRACE 196 extern void ast_dtrace_on(void); 197 extern void dtrace_ast(void); 198 #endif /* CONFIG_DTRACE */ 199 200 extern void kevent_ast(thread_t thread, uint16_t bits); 201 extern void act_set_astkevent(thread_t thread, uint16_t bits); 202 extern uint16_t act_clear_astkevent(thread_t thread, uint16_t bits); 203 extern void act_set_ast_reset_pcs(thread_t thread); 204 205 #endif /* _KERN_AST_H_ */