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git.saurik.com Git - apple/xnu.git/blob - bsd/dev/arm64/dtrace_subr_arm.c
2 * Copyright (c) 2007-2018 Apple Inc. All rights reserved.
7 * The contents of this file are subject to the terms of the
8 * Common Development and Distribution License, Version 1.0 only
9 * (the "License"). You may not use this file except in compliance
12 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
13 * or http://www.opensolaris.org/os/licensing.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
17 * When distributing Covered Code, include this CDDL HEADER in each
18 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
19 * If applicable, add the following below this CDDL HEADER, with the
20 * fields enclosed by brackets "[]" replaced with your own identifying
21 * information: Portions Copyright [yyyy] [name of copyright owner]
26 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
30 #include <sys/dtrace.h>
31 #include <sys/dtrace_glue.h>
32 #include <sys/dtrace_impl.h>
33 #include <sys/fasttrap.h>
36 #include <sys/kauth.h>
37 #include <kern/debug.h>
38 #include <arm/proc_reg.h>
40 int (*dtrace_pid_probe_ptr
)(arm_saved_state_t
*);
41 int (*dtrace_return_probe_ptr
) (arm_saved_state_t
*);
44 dtrace_user_probe(arm_saved_state_t
*);
47 dtrace_user_probe(arm_saved_state_t
*regs
)
52 * The only call path into this method is always a user trap.
53 * We don't need to test for user trap, but should assert it.
57 struct proc
*p
= current_proc();
60 uthread_t uthread
= (uthread_t
)get_bsdthread_info(current_thread());
62 kauth_cred_uthread_update(uthread
, p
);
65 if (copyin((user_addr_t
)saved_state64(regs
)->pc
, &pc
, sizeof(uint32_t))) {
68 is_fasttrap
= (pc
== FASTTRAP_ARM64_RET_INSTR
);
71 uint8_t step
= uthread
->t_dtrace_step
;
72 uint8_t ret
= uthread
->t_dtrace_ret
;
73 user_addr_t npc
= uthread
->t_dtrace_npc
;
75 if (uthread
->t_dtrace_ast
) {
76 printf("dtrace_user_probe() should be calling aston()\n");
78 // uthread->t_sig_check = 1;
82 * Clear all user tracing flags.
84 uthread
->t_dtrace_ft
= 0;
87 * If we weren't expecting a quick return to the kernel, just kill
88 * the process as though it had just executed an unassigned
93 * APPLE NOTE: We're returning KERN_FAILURE, which causes
94 * the generic signal handling code to take over, which will effectively
95 * deliver a EXC_BAD_INSTRUCTION to the user process.
101 * If we hit this trap unrelated to a return probe, we're
104 * 1. Reset the AST flag, since we deferred a signal
105 * until after we logically single-stepped the instruction we
108 * 2. Just return to normal execution (required for U64).
111 set_saved_state_pc(regs
, npc
);
116 * We need to wait until after we've called the
117 * dtrace_return_probe_ptr function pointer to step the pc.
119 rwp
= &CPU
->cpu_ft_lock
;
120 lck_rw_lock_shared(rwp
);
122 if (dtrace_return_probe_ptr
!= NULL
) {
123 (void) (*dtrace_return_probe_ptr
)(regs
);
125 lck_rw_unlock_shared(rwp
);
127 set_saved_state_pc(regs
, npc
);
131 rwp
= &CPU
->cpu_ft_lock
;
134 * The DTrace fasttrap provider uses a trap,
135 * FASTTRAP_{ARM,THUMB}_INSTR. We let
136 * DTrace take the first crack at handling
137 * this trap; if it's not a probe that DTrace knows about,
138 * we call into the trap() routine to handle it like a
139 * breakpoint placed by a conventional debugger.
143 * APPLE NOTE: I believe the purpose of the reader/writers lock
144 * is thus: There are times which dtrace needs to prevent calling
145 * dtrace_pid_probe_ptr(). Sun's original impl grabbed a plain
146 * mutex here. However, that serialized all probe calls, and
147 * destroyed MP behavior. So now they use a RW lock, with probes
148 * as readers, and the top level synchronization as a writer.
150 lck_rw_lock_shared(rwp
);
151 if (dtrace_pid_probe_ptr
!= NULL
&&
152 (*dtrace_pid_probe_ptr
)(regs
) == 0) {
153 lck_rw_unlock_shared(rwp
);
156 lck_rw_unlock_shared(rwp
);
159 * If the instruction that caused the breakpoint trap doesn't
160 * look like our trap anymore, it may be that this tracepoint
161 * was removed just after the user thread executed it. In
162 * that case, return to user land to retry the instuction.
164 * Note that the PC points to the instruction that caused the fault.
167 if (fuword32(saved_state64(regs
)->pc
, &instr
) == 0 && instr
!= FASTTRAP_ARM64_INSTR
) {