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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #ifndef _ONTRAP_H 27 #define _ONTRAP_H 28 29 #pragma ident "%Z%%M% %I% %E% SMI" 30 31 #if !defined(_ASM) 32 #include <sys/types.h> 33 #endif 34 35 #ifdef __cplusplus 36 extern "C" { 37 #endif 38 39 /* 40 * on_trap() provides protection against various kinds of machine exceptions, 41 * and must be used with extreme caution. Like setjmp(), on_trap() returns 42 * zero when explicitly called and non-zero when it returns as the result of 43 * an exception. The caller should not attempt to interpret the actual integer 44 * return value except to test whether it is zero or non-zero. on_trap() and 45 * no_trap() are NOT DDI interfaces for public consumption. For now, the 46 * on_trap() mechanism is separate from on_fault() protection and the t_lofault 47 * protection used by the various copy routines. 48 * 49 * Calls to on_trap() may be nested, but only the most recently installed bits 50 * apply. Protection bits may be OR-ed together if the caller wishes to 51 * protect against more than one type of trap. If on_trap() returns non-zero, 52 * the bit corresponding to the trap that triggered return to on_trap() will 53 * be stored in the ot_trap field of the caller's on_trap_data. 54 * 55 * After calling on_trap(), the caller may elect to modify ot_trampoline to 56 * install a custom trampoline routine prior to executing the protected code 57 * region. No other fields of the on_trap_data should be modified by the 58 * caller. The trampoline may not be applicable on all platforms. 59 * 60 * The on_trap_data structures are kept in a stack (linked list) whose top 61 * is pointed to by the current thread's t_ontrap field. A no_trap() call 62 * pops the top element from the stack and resets t_ontrap to ot_prev. 63 * We assume the caller has allocated the on_trap_data on the stack or 64 * made other arrangements, so we do not need to worry about deallocation. 65 * 66 * If repeated calls to on_trap() are made using the same on_trap_data address, 67 * the topmost stack element is modified in-place (the same on_trap_data is 68 * not pushed twice), allowing callers to use on_trap() in a loop. The act 69 * of catching an exception does NOT modify t_ontrap. Even if on_trap() 70 * returns non-zero, the caller must use no_trap() to clear trap protection. 71 * 72 * Calls to no_trap() are permitted when the on_trap_data stack is empty; they 73 * have no effect. no_trap() only modifies t_ontrap; it does not modify the 74 * internals of the topmost on_trap_data element. It is therefore legal for 75 * callers to examine the contents of the on_trap_data (specifically ot_trap) 76 * after the data is popped using no_trap(). 77 * 78 * A given platform may not implement all the forms of on_trap() protection. 79 * The on_trap_data will be pushed on the t_ontrap stack with ot_prot set 80 * regardless. We must guarantee that if the platform does not implement 81 * a trap protection, the exceptional condition will trigger a panic. We do 82 * not permit a platform to allow the exceptional condition to occur silently 83 * and then continue to execute the caller's protected code region. 84 */ 85 86 #define OT_DATA_ACCESS 0x01 /* data access exception protection */ 87 #define OT_DATA_EC 0x02 /* error correction trap protection */ 88 89 #if defined(__x86) 90 #define OT_SEGMENT_ACCESS 0x03 /* segmentation exception */ 91 #endif 92 93 #if !defined(_ASM) 94 95 typedef struct on_trap_data { 96 ushort_t ot_prot; /* active protection bits (see above) */ 97 ushort_t ot_trap; /* bit of actual trap that occurred */ 98 uintptr_t ot_trampoline; /* %pc for trap return (if any) */ 99 label_t ot_jmpbuf; /* label for longjmp back to on_trap */ 100 struct on_trap_data *ot_prev; /* pointer to previous on_trap_data */ 101 void *ot_handle; /* access handle */ 102 void *ot_pad1; /* reserved for future use */ 103 } on_trap_data_t; 104 105 #if defined(_KERNEL) 106 107 extern int on_trap(on_trap_data_t *, uint_t); 108 #pragma unknown_control_flow(on_trap) 109 extern void no_trap(void); 110 111 extern void on_trap_trampoline(void); /* default trampoline */ 112 113 #endif /* _KERNEL */ 114 #endif /* !_ASM */ 115 116 #ifdef __cplusplus 117 } 118 #endif 119 120 #endif /* _ONTRAP_H */ 121