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1 | /* |
2 | * Copyright (c) 2007 Apple Inc. All rights reserved. | |
3 | * | |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ | |
5 | * | |
6 | * This file contains Original Code and/or Modifications of Original Code | |
7 | * as defined in and that are subject to the Apple Public Source License | |
8 | * Version 2.0 (the 'License'). You may not use this file except in | |
9 | * compliance with the License. The rights granted to you under the License | |
10 | * may not be used to create, or enable the creation or redistribution of, | |
11 | * unlawful or unlicensed copies of an Apple operating system, or to | |
12 | * circumvent, violate, or enable the circumvention or violation of, any | |
13 | * terms of an Apple operating system software license agreement. | |
14 | * | |
15 | * Please obtain a copy of the License at | |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. | |
17 | * | |
18 | * The Original Code and all software distributed under the License are | |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, | |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. | |
23 | * Please see the License for the specific language governing rights and | |
24 | * limitations under the License. | |
25 | * | |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ | |
27 | */ | |
28 | ||
29 | /* | |
30 | * CDDL HEADER START | |
31 | * | |
32 | * The contents of this file are subject to the terms of the | |
33 | * Common Development and Distribution License, Version 1.0 only | |
34 | * (the "License"). You may not use this file except in compliance | |
35 | * with the License. | |
36 | * | |
37 | * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE | |
38 | * or http://www.opensolaris.org/os/licensing. | |
39 | * See the License for the specific language governing permissions | |
40 | * and limitations under the License. | |
41 | * | |
42 | * When distributing Covered Code, include this CDDL HEADER in each | |
43 | * file and include the License file at usr/src/OPENSOLARIS.LICENSE. | |
44 | * If applicable, add the following below this CDDL HEADER, with the | |
45 | * fields enclosed by brackets "[]" replaced with your own identifying | |
46 | * information: Portions Copyright [yyyy] [name of copyright owner] | |
47 | * | |
48 | * CDDL HEADER END | |
49 | */ | |
50 | /* | |
51 | * Copyright 2005 Sun Microsystems, Inc. All rights reserved. | |
52 | * Use is subject to license terms. | |
53 | */ | |
54 | ||
55 | /* | |
56 | * #pragma ident "@(#)dtrace_subr.c 1.12 05/06/08 SMI" | |
57 | */ | |
58 | ||
59 | #define MACH__POSIX_C_SOURCE_PRIVATE 1 /* pulls in suitable savearea from mach/ppc/thread_status.h */ | |
60 | #include <sys/dtrace.h> | |
61 | #include <sys/dtrace_glue.h> | |
62 | #include <sys/dtrace_impl.h> | |
63 | #include <sys/fasttrap.h> | |
64 | #include <sys/vm.h> | |
65 | #include <sys/user.h> | |
66 | #include <sys/kauth.h> | |
67 | #include <kern/debug.h> | |
68 | ||
69 | int (*dtrace_pid_probe_ptr)(ppc_saved_state_t *); | |
70 | int (*dtrace_return_probe_ptr)(ppc_saved_state_t *); | |
71 | kern_return_t dtrace_user_probe(ppc_saved_state_t *sv); | |
72 | ||
73 | kern_return_t | |
74 | dtrace_user_probe(ppc_saved_state_t *sv) | |
75 | { | |
76 | ||
77 | lck_rw_t *rwp; | |
78 | struct proc *p = current_proc(); | |
79 | ||
80 | uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread()); | |
81 | /* | |
82 | * DTrace accesses t_cred in probe context. t_cred | |
83 | * must always be either NULL, or point to a valid, | |
84 | * allocated cred structure. | |
85 | */ | |
86 | kauth_cred_uthread_update(uthread, p); | |
87 | ||
88 | if (sv->save_exception == T_DTRACE_RET) { | |
89 | ||
90 | /* | |
91 | * T_DTRACE_RET is generated by the kernel when an emulation sequence | |
92 | * ends. Unlike the x86 implementation, this can not be caused by | |
93 | * a user state trap instruction. It is a system error if it occurs | |
94 | * when not stepping and is, therefore, a panickable offence. | |
95 | */ | |
96 | ||
97 | if(uthread->t_dtrace_step == 0) { /* Are we supposed to be tracing? */ | |
98 | panic("dtrace_user_probe: T_DTRACE_RET when not stepping\n"); | |
99 | } | |
100 | ||
101 | if (uthread->t_dtrace_ast) { | |
102 | printf("dtrace_user_probe() should be calling aston()\n"); | |
103 | // aston(uthread); | |
104 | // uthread->t_sig_check = 1; | |
105 | } | |
106 | ||
107 | /* | |
108 | * Clear all user tracing flags. | |
109 | */ | |
110 | uthread->t_dtrace_ft = 0; | |
111 | ||
112 | /* | |
113 | * We need to wait until after we've called the | |
114 | * dtrace_return_probe_ptr function pointer to step the pc. | |
115 | */ | |
116 | rwp = &CPU->cpu_ft_lock; | |
117 | lck_rw_lock_shared(rwp); | |
118 | ||
119 | if (dtrace_return_probe_ptr != NULL) (void)(*dtrace_return_probe_ptr)(sv); | |
120 | lck_rw_unlock_shared(rwp); | |
121 | ||
122 | sv->save_srr0 = sv->save_srr0 + 4; /* Step to next instruction */ | |
123 | if(!(sv->save_srr1 & 0x8000000000000000ULL)) sv->save_srr0 &= 0x00000000FFFFFFFF; /* Trim if in 32-bit mode */ | |
124 | ||
125 | return KERN_SUCCESS; | |
126 | ||
127 | } else { | |
128 | ||
129 | /* | |
130 | * We have taken our normal trap to get here. Make sure we expect it | |
131 | */ | |
132 | uint32_t instr; | |
133 | rwp = &CPU->cpu_ft_lock; | |
134 | ||
135 | /* | |
136 | * The DTrace fasttrap provider uses a trap, "twi 31,r31,0xDDDD". | |
137 | * We will only be here if dtrace (or someone pretending to be us) | |
138 | * sets the trap. | |
139 | * We let DTrace take the first crack at handling | |
140 | * this trap; if it's not a probe that DTrace knowns about, | |
141 | * we call into the trap() routine to handle it like a | |
142 | * breakpoint placed by a conventional debugger. | |
143 | */ | |
144 | ||
145 | /* | |
146 | * APPLE NOTE: I believe the purpose of the reader/writers lock | |
147 | * is thus: There are times which dtrace needs to prevent calling | |
148 | * dtrace_pid_probe_ptr(). Sun's original impl grabbed a plain | |
149 | * mutex here. However, that serialized all probe calls, and | |
150 | * destroyed MP behavior. So now they use a RW lock, with probes | |
151 | * as readers, and the top level synchronization as a writer. | |
152 | */ | |
153 | lck_rw_lock_shared(rwp); | |
154 | if (dtrace_pid_probe_ptr != NULL && | |
155 | (*dtrace_pid_probe_ptr)(sv) == 0) { | |
156 | lck_rw_unlock_shared(rwp); | |
157 | return KERN_SUCCESS; | |
158 | } | |
159 | lck_rw_unlock_shared(rwp); | |
160 | ||
161 | /* | |
162 | * If the instruction that caused the breakpoint trap doesn't | |
163 | * look like our trap anymore, it may be that this tracepoint | |
164 | * was removed just after the user thread executed it. In | |
165 | * that case, return to user land to retry the instuction. | |
166 | * | |
167 | * Note that the PC is correct because we do not advance it until after emulation. | |
168 | */ | |
169 | if (fuword32(sv->save_srr0, &instr) == 0 && instr != FASTTRAP_INSTR) { | |
170 | return KERN_SUCCESS; | |
171 | } | |
172 | ||
173 | } | |
174 | ||
175 | /* | |
176 | * If we get here, we go back to throw an exception | |
177 | */ | |
178 | ||
179 | return KERN_FAILURE; | |
180 | } | |
181 | ||
182 | void | |
183 | dtrace_safe_synchronous_signal(void) | |
184 | { | |
185 | // This is commented out of the x86 code and is never called. | |
186 | } | |
187 | ||
188 | int | |
189 | dtrace_safe_defer_signal(void) | |
190 | { | |
191 | // This is commented out of the x86 code and is never called. | |
192 | return 0; | |
193 | } |