1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #ifndef _ONTRAP_H 28 #define _ONTRAP_H 29 30 #pragma ident "%Z%%M% %I% %E% SMI" 31 32 #if !defined(_ASM) 33 #include <sys/types.h> 34 #endif 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /* 41 * on_trap() provides protection against various kinds of machine exceptions, 42 * and must be used with extreme caution. Like setjmp(), on_trap() returns 43 * zero when explicitly called and non-zero when it returns as the result of 44 * an exception. The caller should not attempt to interpret the actual integer 45 * return value except to test whether it is zero or non-zero. on_trap() and 46 * no_trap() are NOT DDI interfaces for public consumption. For now, the 47 * on_trap() mechanism is separate from on_fault() protection and the t_lofault 48 * protection used by the various copy routines. 49 * 50 * Calls to on_trap() may be nested, but only the most recently installed bits 51 * apply. Protection bits may be OR-ed together if the caller wishes to 52 * protect against more than one type of trap. If on_trap() returns non-zero, 53 * the bit corresponding to the trap that triggered return to on_trap() will 54 * be stored in the ot_trap field of the caller's on_trap_data. 55 * 56 * After calling on_trap(), the caller may elect to modify ot_trampoline to 57 * install a custom trampoline routine prior to executing the protected code 58 * region. No other fields of the on_trap_data should be modified by the 59 * caller. The trampoline may not be applicable on all platforms. 60 * 61 * The on_trap_data structures are kept in a stack (linked list) whose top 62 * is pointed to by the current thread's t_ontrap field. A no_trap() call 63 * pops the top element from the stack and resets t_ontrap to ot_prev. 64 * We assume the caller has allocated the on_trap_data on the stack or 65 * made other arrangements, so we do not need to worry about deallocation. 66 * 67 * If repeated calls to on_trap() are made using the same on_trap_data address, 68 * the topmost stack element is modified in-place (the same on_trap_data is 69 * not pushed twice), allowing callers to use on_trap() in a loop. The act 70 * of catching an exception does NOT modify t_ontrap. Even if on_trap() 71 * returns non-zero, the caller must use no_trap() to clear trap protection. 72 * 73 * Calls to no_trap() are permitted when the on_trap_data stack is empty; they 74 * have no effect. no_trap() only modifies t_ontrap; it does not modify the 75 * internals of the topmost on_trap_data element. It is therefore legal for 76 * callers to examine the contents of the on_trap_data (specifically ot_trap) 77 * after the data is popped using no_trap(). 78 * 79 * A given platform may not implement all the forms of on_trap() protection. 80 * The on_trap_data will be pushed on the t_ontrap stack with ot_prot set 81 * regardless. We must guarantee that if the platform does not implement 82 * a trap protection, the exceptional condition will trigger a panic. We do 83 * not permit a platform to allow the exceptional condition to occur silently 84 * and then continue to execute the caller's protected code region. 85 */ 86 87 #define OT_DATA_ACCESS 0x01 /* data access exception protection */ 88 #define OT_DATA_EC 0x02 /* error correction trap protection */ 89 90 #if !defined(_ASM) 91 92 typedef struct on_trap_data { 93 ushort_t ot_prot; /* active protection bits (see above) */ 94 ushort_t ot_trap; /* bit of actual trap that occurred */ 95 uintptr_t ot_trampoline; /* %pc for trap return (if any) */ 96 label_t ot_jmpbuf; /* label for longjmp back to on_trap */ 97 struct on_trap_data *ot_prev; /* pointer to previous on_trap_data */ 98 void *ot_handle; /* access handle */ 99 void *ot_pad1; /* reserved for future use */ 100 } on_trap_data_t; 101 102 #if defined(_KERNEL) 103 104 extern int on_trap(on_trap_data_t *, uint_t); 105 #pragma unknown_control_flow(on_trap) 106 extern void no_trap(void); 107 108 extern void on_trap_trampoline(void); /* default trampoline */ 109 110 #endif /* _KERNEL */ 111 #endif /* !_ASM */ 112 113 #ifdef __cplusplus 114 } 115 #endif 116 117 #endif /* _ONTRAP_H */ 118