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 #if !defined(_ASM) 30 #include <sys/types.h> 31 #endif 32 33 #ifdef __cplusplus 34 extern "C" { 35 #endif 36 37 /* 38 * on_trap() provides protection against various kinds of machine exceptions, 39 * and must be used with extreme caution. Like setjmp(), on_trap() returns 40 * zero when explicitly called and non-zero when it returns as the result of 41 * an exception. The caller should not attempt to interpret the actual integer 42 * return value except to test whether it is zero or non-zero. on_trap() and 43 * no_trap() are NOT DDI interfaces for public consumption. For now, the 44 * on_trap() mechanism is separate from on_fault() protection and the t_lofault 45 * protection used by the various copy routines. 46 * 47 * Calls to on_trap() may be nested, but only the most recently installed bits 48 * apply. Protection bits may be OR-ed together if the caller wishes to 49 * protect against more than one type of trap. If on_trap() returns non-zero, 50 * the bit corresponding to the trap that triggered return to on_trap() will 51 * be stored in the ot_trap field of the caller's on_trap_data. 52 * 53 * After calling on_trap(), the caller may elect to modify ot_trampoline to 54 * install a custom trampoline routine prior to executing the protected code 55 * region. No other fields of the on_trap_data should be modified by the 56 * caller. The trampoline may not be applicable on all platforms. 57 * 58 * The on_trap_data structures are kept in a stack (linked list) whose top 59 * is pointed to by the current thread's t_ontrap field. A no_trap() call 60 * pops the top element from the stack and resets t_ontrap to ot_prev. 61 * We assume the caller has allocated the on_trap_data on the stack or 62 * made other arrangements, so we do not need to worry about deallocation. 63 * 64 * If repeated calls to on_trap() are made using the same on_trap_data address, 65 * the topmost stack element is modified in-place (the same on_trap_data is 66 * not pushed twice), allowing callers to use on_trap() in a loop. The act 67 * of catching an exception does NOT modify t_ontrap. Even if on_trap() 68 * returns non-zero, the caller must use no_trap() to clear trap protection. 69 * 70 * Calls to no_trap() are permitted when the on_trap_data stack is empty; they 71 * have no effect. no_trap() only modifies t_ontrap; it does not modify the 72 * internals of the topmost on_trap_data element. It is therefore legal for 73 * callers to examine the contents of the on_trap_data (specifically ot_trap) 74 * after the data is popped using no_trap(). 75 * 76 * A given platform may not implement all the forms of on_trap() protection. 77 * The on_trap_data will be pushed on the t_ontrap stack with ot_prot set 78 * regardless. We must guarantee that if the platform does not implement 79 * a trap protection, the exceptional condition will trigger a panic. We do 80 * not permit a platform to allow the exceptional condition to occur silently 81 * and then continue to execute the caller's protected code region. 82 */ 83 84 #define OT_DATA_ACCESS 0x01 /* data access exception protection */ 85 #define OT_DATA_EC 0x02 /* error correction trap protection */ 86 87 #if defined(__x86) 88 #define OT_SEGMENT_ACCESS 0x03 /* segmentation exception */ 89 #endif 90 91 #if !defined(_ASM) 92 93 typedef struct on_trap_data { 94 ushort_t ot_prot; /* active protection bits (see above) */ 95 ushort_t ot_trap; /* bit of actual trap that occurred */ 96 uintptr_t ot_trampoline; /* %pc for trap return (if any) */ 97 label_t ot_jmpbuf; /* label for longjmp back to on_trap */ 98 struct on_trap_data *ot_prev; /* pointer to previous on_trap_data */ 99 void *ot_handle; /* access handle */ 100 void *ot_pad1; /* reserved for future use */ 101 } on_trap_data_t; 102 103 #if defined(_KERNEL) 104 105 extern int on_trap(on_trap_data_t *, uint_t) __RETURNS_TWICE; 106 #pragma unknown_control_flow(on_trap) 107 extern void no_trap(void); 108 109 extern void on_trap_trampoline(void); /* default trampoline */ 110 111 #endif /* _KERNEL */ 112 #endif /* !_ASM */ 113 114 #ifdef __cplusplus 115 } 116 #endif 117 118 #endif /* _ONTRAP_H */ 119