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28f540f4 | 1 | /* Set thread_state for sighandler, and sigcontext to recover. i386 version. |
04277e02 | 2 | Copyright (C) 1994-2019 Free Software Foundation, Inc. |
478b92f0 | 3 | This file is part of the GNU C Library. |
28f540f4 | 4 | |
478b92f0 | 5 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
28f540f4 | 9 | |
478b92f0 UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
28f540f4 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
28f540f4 RM |
18 | |
19 | #include <hurd/signal.h> | |
e607b492 | 20 | #include <hurd/userlink.h> |
8f480b4b | 21 | #include <thread_state.h> |
d2ea0b96 | 22 | #include <mach/machine/eflags.h> |
28f540f4 RM |
23 | #include <assert.h> |
24 | #include <errno.h> | |
25 | #include "hurdfault.h" | |
8f480b4b | 26 | #include <intr-msg.h> |
28f540f4 | 27 | |
7974fe21 | 28 | |
28f540f4 RM |
29 | struct sigcontext * |
30 | _hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler, | |
0e3426bb | 31 | int signo, struct hurd_signal_detail *detail, |
28f540f4 RM |
32 | volatile int rpc_wait, |
33 | struct machine_thread_all_state *state) | |
34 | { | |
83ddec31 RM |
35 | void trampoline (void); |
36 | void rpc_wait_trampoline (void); | |
37 | void firewall (void); | |
3fe9de0d RM |
38 | extern const void _hurd_intr_rpc_msg_cx_sp; |
39 | extern const void _hurd_intr_rpc_msg_sp_restored; | |
28f540f4 RM |
40 | void *volatile sigsp; |
41 | struct sigcontext *scp; | |
7974fe21 | 42 | struct |
28f540f4 RM |
43 | { |
44 | int signo; | |
45 | long int sigcode; | |
46 | struct sigcontext *scp; /* Points to ctx, below. */ | |
f0bf9cb9 RM |
47 | void *sigreturn_addr; |
48 | void *sigreturn_returns_here; | |
28f540f4 RM |
49 | struct sigcontext *return_scp; /* Same; arg to sigreturn. */ |
50 | struct sigcontext ctx; | |
e607b492 | 51 | struct hurd_userlink link; |
28f540f4 RM |
52 | } *stackframe; |
53 | ||
54 | if (ss->context) | |
55 | { | |
56 | /* We have a previous sigcontext that sigreturn was about | |
57 | to restore when another signal arrived. We will just base | |
58 | our setup on that. */ | |
7974fe21 | 59 | if (! _hurdsig_catch_memory_fault (ss->context)) |
28f540f4 RM |
60 | { |
61 | memcpy (&state->basic, &ss->context->sc_i386_thread_state, | |
62 | sizeof (state->basic)); | |
63 | memcpy (&state->fpu, &ss->context->sc_i386_float_state, | |
64 | sizeof (state->fpu)); | |
f8baf2a2 | 65 | state->set |= (1 << i386_REGS_SEGS_STATE) | (1 << i386_FLOAT_STATE); |
28f540f4 | 66 | } |
28f540f4 | 67 | } |
421f82e5 RM |
68 | |
69 | if (! machine_get_basic_state (ss->thread, state)) | |
28f540f4 RM |
70 | return NULL; |
71 | ||
3fe9de0d RM |
72 | /* Save the original SP in the gratuitous `esp' slot. |
73 | We may need to reset the SP (the `uesp' slot) to avoid clobbering an | |
74 | interrupted RPC frame. */ | |
75 | state->basic.esp = state->basic.uesp; | |
76 | ||
aa0e4663 JM |
77 | if ((ss->actions[signo].sa_flags & SA_ONSTACK) |
78 | && !(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK))) | |
28f540f4 RM |
79 | { |
80 | sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size; | |
7ce241a0 | 81 | ss->sigaltstack.ss_flags |= SS_ONSTACK; |
28f540f4 | 82 | } |
3fe9de0d | 83 | /* This code has intimate knowledge of the special mach_msg system call |
4ca84cff | 84 | done in intr-msg.c; that code does (see intr-msg.h): |
3fe9de0d RM |
85 | movl %esp, %ecx |
86 | leal ARGS, %esp | |
87 | _hurd_intr_rpc_msg_cx_sp: movl $-25, %eax | |
88 | _hurd_intr_rpc_msg_do_trap: lcall $7, $0 | |
89 | _hurd_intr_rpc_msg_in_trap: movl %ecx, %esp | |
478b92f0 | 90 | _hurd_intr_rpc_msg_sp_restored: |
3fe9de0d RM |
91 | We must check for the window during which %esp points at the |
92 | mach_msg arguments. The space below until %ecx is used by | |
93 | the _hurd_intr_rpc_mach_msg frame, and must not be clobbered. */ | |
aa0e4663 JM |
94 | else if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp |
95 | && state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored) | |
3fe9de0d RM |
96 | /* The SP now points at the mach_msg args, but there is more stack |
97 | space used below it. The real SP is saved in %ecx; we must push the | |
98 | new frame below there, and restore that value as the SP on | |
99 | sigreturn. */ | |
100 | sigsp = (char *) (state->basic.uesp = state->basic.ecx); | |
28f540f4 RM |
101 | else |
102 | sigsp = (char *) state->basic.uesp; | |
103 | ||
104 | /* Push the arguments to call `trampoline' on the stack. */ | |
105 | sigsp -= sizeof (*stackframe); | |
106 | stackframe = sigsp; | |
107 | ||
7974fe21 | 108 | if (_hurdsig_catch_memory_fault (stackframe)) |
28f540f4 | 109 | { |
28f540f4 RM |
110 | /* We got a fault trying to write the stack frame. |
111 | We cannot set up the signal handler. | |
112 | Returning NULL tells our caller, who will nuke us with a SIGILL. */ | |
113 | return NULL; | |
114 | } | |
115 | else | |
116 | { | |
117 | int ok; | |
118 | ||
e607b492 RM |
119 | extern void _hurdsig_longjmp_from_handler (void *, jmp_buf, int); |
120 | ||
121 | /* Add a link to the thread's active-resources list. We mark this as | |
122 | the only user of the "resource", so the cleanup function will be | |
123 | called by any longjmp which is unwinding past the signal frame. | |
124 | The cleanup function (in sigunwind.c) will make sure that all the | |
125 | appropriate cleanups done by sigreturn are taken care of. */ | |
126 | stackframe->link.cleanup = &_hurdsig_longjmp_from_handler; | |
127 | stackframe->link.cleanup_data = &stackframe->ctx; | |
128 | stackframe->link.resource.next = NULL; | |
129 | stackframe->link.resource.prevp = NULL; | |
130 | stackframe->link.thread.next = ss->active_resources; | |
131 | stackframe->link.thread.prevp = &ss->active_resources; | |
132 | if (stackframe->link.thread.next) | |
133 | stackframe->link.thread.next->thread.prevp | |
134 | = &stackframe->link.thread.next; | |
135 | ss->active_resources = &stackframe->link; | |
136 | ||
28f540f4 RM |
137 | /* Set up the arguments for the signal handler. */ |
138 | stackframe->signo = signo; | |
0e3426bb | 139 | stackframe->sigcode = detail->code; |
28f540f4 | 140 | stackframe->scp = stackframe->return_scp = scp = &stackframe->ctx; |
f0bf9cb9 | 141 | stackframe->sigreturn_addr = &__sigreturn; |
83ddec31 | 142 | stackframe->sigreturn_returns_here = firewall; /* Crash on return. */ |
28f540f4 RM |
143 | |
144 | /* Set up the sigcontext from the current state of the thread. */ | |
145 | ||
7ce241a0 | 146 | scp->sc_onstack = ss->sigaltstack.ss_flags & SS_ONSTACK ? 1 : 0; |
28f540f4 RM |
147 | |
148 | /* struct sigcontext is laid out so that starting at sc_gs mimics a | |
149 | struct i386_thread_state. */ | |
150 | memcpy (&scp->sc_i386_thread_state, | |
151 | &state->basic, sizeof (state->basic)); | |
152 | ||
153 | /* struct sigcontext is laid out so that starting at sc_fpkind mimics | |
154 | a struct i386_float_state. */ | |
155 | ok = machine_get_state (ss->thread, state, i386_FLOAT_STATE, | |
156 | &state->fpu, &scp->sc_i386_float_state, | |
157 | sizeof (state->fpu)); | |
158 | ||
159 | _hurdsig_end_catch_fault (); | |
160 | ||
161 | if (! ok) | |
162 | return NULL; | |
163 | } | |
164 | ||
165 | /* Modify the thread state to call the trampoline code on the new stack. */ | |
166 | if (rpc_wait) | |
167 | { | |
168 | /* The signalee thread was blocked in a mach_msg_trap system call, | |
169 | still waiting for a reply. We will have it run the special | |
170 | trampoline code which retries the message receive before running | |
171 | the signal handler. | |
7974fe21 | 172 | |
28f540f4 RM |
173 | To do this we change the OPTION argument on its stack to enable only |
174 | message reception, since the request message has already been | |
175 | sent. */ | |
176 | ||
3fe9de0d | 177 | struct mach_msg_trap_args *args = (void *) state->basic.esp; |
28f540f4 | 178 | |
7974fe21 | 179 | if (_hurdsig_catch_memory_fault (args)) |
28f540f4 | 180 | { |
28f540f4 RM |
181 | /* Faulted accessing ARGS. Bomb. */ |
182 | return NULL; | |
183 | } | |
184 | ||
185 | assert (args->option & MACH_RCV_MSG); | |
186 | /* Disable the message-send, since it has already completed. The | |
187 | calls we retry need only wait to receive the reply message. */ | |
188 | args->option &= ~MACH_SEND_MSG; | |
189 | ||
54da5be3 RM |
190 | /* Limit the time to receive the reply message, in case the server |
191 | claimed that `interrupt_operation' succeeded but in fact the RPC | |
192 | is hung. */ | |
193 | args->option |= MACH_RCV_TIMEOUT; | |
194 | args->timeout = _hurd_interrupted_rpc_timeout; | |
195 | ||
28f540f4 RM |
196 | _hurdsig_end_catch_fault (); |
197 | ||
83ddec31 | 198 | state->basic.eip = (int) rpc_wait_trampoline; |
28f540f4 RM |
199 | /* The reply-receiving trampoline code runs initially on the original |
200 | user stack. We pass it the signal stack pointer in %ebx. */ | |
3fe9de0d | 201 | state->basic.uesp = state->basic.esp; /* Restore mach_msg syscall SP. */ |
28f540f4 RM |
202 | state->basic.ebx = (int) sigsp; |
203 | /* After doing the message receive, the trampoline code will need to | |
204 | update the %eax value to be restored by sigreturn. To simplify | |
205 | the assembly code, we pass the address of its slot in SCP to the | |
206 | trampoline code in %ecx. */ | |
207 | state->basic.ecx = (int) &scp->sc_eax; | |
208 | } | |
209 | else | |
210 | { | |
83ddec31 | 211 | state->basic.eip = (int) trampoline; |
28f540f4 RM |
212 | state->basic.uesp = (int) sigsp; |
213 | } | |
214 | /* We pass the handler function to the trampoline code in %edx. */ | |
215 | state->basic.edx = (int) handler; | |
216 | ||
d2ea0b96 RM |
217 | /* The x86 ABI says the DF bit is clear on entry to any function. */ |
218 | state->basic.efl &= ~EFL_DF; | |
219 | ||
28f540f4 | 220 | return scp; |
83ddec31 | 221 | } |
28f540f4 | 222 | |
83ddec31 RM |
223 | /* The trampoline code follows. This used to be located inside |
224 | _hurd_setup_sighandler, but was optimized away by gcc 2.95. */ | |
28f540f4 | 225 | |
83ddec31 | 226 | asm ("rpc_wait_trampoline:\n"); |
28f540f4 RM |
227 | /* This is the entry point when we have an RPC reply message to receive |
228 | before running the handler. The MACH_MSG_SEND bit has already been | |
229 | cleared in the OPTION argument on our stack. The interrupted user | |
230 | stack pointer has not been changed, so the system call can find its | |
231 | arguments; the signal stack pointer is in %ebx. For our convenience, | |
232 | %ecx points to the sc_eax member of the sigcontext. */ | |
83ddec31 | 233 | asm (/* Retry the interrupted mach_msg system call. */ |
28f540f4 RM |
234 | "movl $-25, %eax\n" /* mach_msg_trap */ |
235 | "lcall $7, $0\n" | |
236 | /* When the sigcontext was saved, %eax was MACH_RCV_INTERRUPTED. But | |
237 | now the message receive has completed and the original caller of | |
238 | the RPC (i.e. the code running when the signal arrived) needs to | |
239 | see the final return value of the message receive in %eax. So | |
240 | store the new %eax value into the sc_eax member of the sigcontext | |
241 | (whose address is in %ecx to make this code simpler). */ | |
242 | "movl %eax, (%ecx)\n" | |
243 | /* Switch to the signal stack. */ | |
244 | "movl %ebx, %esp\n"); | |
245 | ||
83ddec31 | 246 | asm ("trampoline:\n"); |
28f540f4 RM |
247 | /* Entry point for running the handler normally. The arguments to the |
248 | handler function are already on the top of the stack: | |
249 | ||
250 | 0(%esp) SIGNO | |
251 | 4(%esp) SIGCODE | |
252 | 8(%esp) SCP | |
253 | */ | |
83ddec31 | 254 | asm ("call *%edx\n" /* Call the handler function. */ |
f0bf9cb9 RM |
255 | "addl $12, %esp\n" /* Pop its args. */ |
256 | /* The word at the top of stack is &__sigreturn; following are a dummy | |
257 | word to fill the slot for the address for __sigreturn to return to, | |
258 | and a copy of SCP for __sigreturn's argument. "Return" to calling | |
259 | __sigreturn (SCP); this call never returns. */ | |
260 | "ret"); | |
28f540f4 | 261 | |
83ddec31 RM |
262 | asm ("firewall:\n" |
263 | "hlt"); |