1 | /* Handle faults in the signal thread. |
2 | Copyright (C) 1994-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <hurd.h> |
20 | #include <hurd/signal.h> |
21 | #include "hurdfault.h" |
22 | #include <errno.h> |
23 | #include <string.h> |
24 | #include <setjmp.h> |
25 | #include <stdio.h> |
26 | #include <thread_state.h> |
27 | #include "faultexc_server.h" /* mig-generated header for our exc server. */ |
28 | #include <assert.h> |
29 | |
30 | jmp_buf _hurdsig_fault_env; |
31 | struct hurd_signal_preemptor _hurdsig_fault_preemptor = {0}; |
32 | |
33 | /* XXX temporary to deal with spelling fix */ |
34 | weak_alias (_hurdsig_fault_preemptor, _hurdsig_fault_preempter) |
35 | |
36 | static mach_port_t forward_sigexc; |
37 | |
38 | kern_return_t |
39 | _hurdsig_fault_catch_exception_raise (mach_port_t port, |
40 | thread_t thread, |
41 | task_t task, |
42 | #ifdef EXC_MASK_ALL /* New interface flavor. */ |
43 | exception_type_t exception, |
44 | exception_data_t code, |
45 | mach_msg_type_number_t codeCnt |
46 | #else /* Vanilla Mach 3.0 interface. */ |
47 | integer_t exception, |
48 | integer_t code, integer_t subcode |
49 | #endif |
50 | ) |
51 | { |
52 | int signo; |
53 | struct hurd_signal_detail d; |
54 | |
55 | if (port != forward_sigexc |
56 | || thread != _hurd_msgport_thread || task != __mach_task_self ()) |
57 | return EPERM; /* Strange bogosity. */ |
58 | |
59 | d.exc = exception; |
60 | #ifdef EXC_MASK_ALL |
61 | assert (codeCnt >= 2); |
62 | d.exc_code = code[0]; |
63 | d.exc_subcode = code[1]; |
64 | #else |
65 | d.exc_code = code; |
66 | d.exc_subcode = subcode; |
67 | #endif |
68 | |
69 | /* Call the machine-dependent function to translate the Mach exception |
70 | codes into a signal number and subcode. */ |
71 | _hurd_exception2signal (detail: &d, signo: &signo); |
72 | |
73 | return HURD_PREEMPT_SIGNAL_P (&_hurdsig_fault_preemptor, signo, d.exc_subcode) |
74 | ? 0 : EGREGIOUS; |
75 | } |
76 | |
77 | #ifdef EXC_MASK_ALL |
78 | /* XXX New interface flavor has additional RPCs that we could be using |
79 | instead. These RPCs roll a thread_get_state/thread_set_state into |
80 | the message, so the signal thread ought to use these to save some calls. |
81 | */ |
82 | kern_return_t |
83 | _hurdsig_fault_catch_exception_raise_state |
84 | (mach_port_t port, |
85 | exception_type_t exception, |
86 | exception_data_t code, |
87 | mach_msg_type_number_t codeCnt, |
88 | int *flavor, |
89 | thread_state_t old_state, |
90 | mach_msg_type_number_t old_stateCnt, |
91 | thread_state_t new_state, |
92 | mach_msg_type_number_t *new_stateCnt) |
93 | { |
94 | abort (); |
95 | return KERN_FAILURE; |
96 | } |
97 | |
98 | kern_return_t |
99 | _hurdsig_fault_catch_exception_raise_state_identity |
100 | (mach_port_t exception_port, |
101 | thread_t thread, |
102 | task_t task, |
103 | exception_type_t exception, |
104 | exception_data_t code, |
105 | mach_msg_type_number_t codeCnt, |
106 | int *flavor, |
107 | thread_state_t old_state, |
108 | mach_msg_type_number_t old_stateCnt, |
109 | thread_state_t new_state, |
110 | mach_msg_type_number_t *new_stateCnt) |
111 | { |
112 | abort (); |
113 | return KERN_FAILURE; |
114 | } |
115 | #endif |
116 | |
117 | |
118 | #ifdef NDR_CHAR_ASCII /* OSF Mach flavors have different names. */ |
119 | # define mig_reply_header_t mig_reply_error_t |
120 | #endif |
121 | |
122 | static void |
123 | faulted (void) |
124 | { |
125 | struct |
126 | { |
127 | mach_msg_header_t head; |
128 | char buf[64]; |
129 | } request; |
130 | mig_reply_header_t reply; |
131 | extern int _hurdsig_fault_exc_server (mach_msg_header_t *, |
132 | mach_msg_header_t *); |
133 | |
134 | /* Wait for the exception_raise message forwarded by the proc server. */ |
135 | |
136 | if (__mach_msg (&request.head, MACH_RCV_MSG, 0, |
137 | sizeof request, forward_sigexc, |
138 | MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL) |
139 | != MACH_MSG_SUCCESS) |
140 | __libc_fatal (message: "msg receive failed on signal thread exc\n" ); |
141 | |
142 | /* Run the exc demuxer which should call the server function above. |
143 | That function returns 0 if the exception was expected. */ |
144 | _hurdsig_fault_exc_server (&request.head, &reply.Head); |
145 | if (reply.Head.msgh_remote_port != MACH_PORT_NULL) |
146 | __mach_msg (&reply.Head, MACH_SEND_MSG, reply.Head.msgh_size, |
147 | 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); |
148 | if (reply.RetCode == MIG_BAD_ID) |
149 | __mach_msg_destroy (&request.head); |
150 | |
151 | if (reply.RetCode) |
152 | __libc_fatal (message: "BUG: unexpected fault in signal thread\n" ); |
153 | |
154 | _hurdsig_fault_preemptor.signals = 0; |
155 | longjmp (env: _hurdsig_fault_env, val: 1); |
156 | } |
157 | |
158 | static char faultstack[1024]; |
159 | |
160 | /* Send exceptions for the signal thread to the proc server. |
161 | It will forward the message on to our message port, |
162 | and then restore the thread's state to code which |
163 | does `longjmp (_hurd_sigthread_fault_env, 1)'. */ |
164 | |
165 | void |
166 | _hurdsig_fault_init (void) |
167 | { |
168 | error_t err; |
169 | struct machine_thread_state state; |
170 | mach_port_t sigexc; |
171 | |
172 | /* Allocate a port to receive signal thread exceptions. |
173 | We will move this receive right to the proc server. */ |
174 | err = __mach_port_allocate (__mach_task_self (), |
175 | MACH_PORT_RIGHT_RECEIVE, &sigexc); |
176 | assert_perror (err); |
177 | err = __mach_port_allocate (__mach_task_self (), |
178 | MACH_PORT_RIGHT_RECEIVE, &forward_sigexc); |
179 | assert_perror (err); |
180 | |
181 | /* Allocate a port to receive the exception msgs forwarded |
182 | from the proc server. */ |
183 | err = __mach_port_insert_right (__mach_task_self (), sigexc, |
184 | sigexc, MACH_MSG_TYPE_MAKE_SEND); |
185 | assert_perror (err); |
186 | |
187 | /* Set the queue limit for this port to just one. The proc server will |
188 | notice if we ever get a second exception while one remains queued and |
189 | unreceived, and decide we are hopelessly buggy. */ |
190 | #ifdef MACH_PORT_RECEIVE_STATUS_COUNT |
191 | { |
192 | const mach_port_limits_t lim = { mpl_qlimit: 1 }; |
193 | assert (MACH_PORT_RECEIVE_STATUS_COUNT == sizeof lim / sizeof (natural_t)); |
194 | err = __mach_port_set_attributes (__mach_task_self (), forward_sigexc, |
195 | MACH_PORT_RECEIVE_STATUS, |
196 | (mach_port_info_t) &lim, |
197 | MACH_PORT_RECEIVE_STATUS_COUNT); |
198 | } |
199 | #else |
200 | err = __mach_port_set_qlimit (__mach_task_self (), forward_sigexc, 1); |
201 | #endif |
202 | assert_perror (err); |
203 | |
204 | /* This state will be restored when we fault. |
205 | It runs the function above. */ |
206 | memset (&state, 0, sizeof state); |
207 | MACHINE_THREAD_STATE_FIX_NEW (&state); |
208 | MACHINE_THREAD_STATE_SET_PC (&state, faulted); |
209 | MACHINE_THREAD_STATE_SET_SP (&state, faultstack, sizeof faultstack); |
210 | |
211 | err = __USEPORT |
212 | (PROC, |
213 | __proc_handle_exceptions (port, |
214 | sigexc, |
215 | forward_sigexc, MACH_MSG_TYPE_MAKE_SEND, |
216 | MACHINE_THREAD_STATE_FLAVOR, |
217 | (natural_t *) &state, |
218 | MACHINE_THREAD_STATE_COUNT)); |
219 | assert_perror (err); |
220 | |
221 | /* Direct signal thread exceptions to the proc server. */ |
222 | #ifdef THREAD_EXCEPTION_PORT |
223 | err = __thread_set_special_port (_hurd_msgport_thread, |
224 | THREAD_EXCEPTION_PORT, sigexc); |
225 | #elif defined (EXC_MASK_ALL) |
226 | __thread_set_exception_ports (_hurd_msgport_thread, |
227 | EXC_MASK_ALL & ~(EXC_MASK_SYSCALL |
228 | | EXC_MASK_MACH_SYSCALL |
229 | | EXC_MASK_RPC_ALERT), |
230 | sigexc, |
231 | EXCEPTION_STATE_IDENTITY, |
232 | MACHINE_THREAD_STATE); |
233 | #else |
234 | # error thread_set_exception_ports? |
235 | #endif |
236 | __mach_port_deallocate (__mach_task_self (), sigexc); |
237 | assert_perror (err); |
238 | } |
239 | |