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ac689eb7 JB |
1 | /* |
2 | * OpenRISC signal.c | |
3 | * | |
4 | * Linux architectural port borrowing liberally from similar works of | |
5 | * others. All original copyrights apply as per the original source | |
6 | * declaration. | |
7 | * | |
8 | * Modifications for the OpenRISC architecture: | |
9 | * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> | |
10 | * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
16 | */ | |
17 | ||
18 | #include <linux/sched.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/smp.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/signal.h> | |
23 | #include <linux/errno.h> | |
24 | #include <linux/wait.h> | |
25 | #include <linux/ptrace.h> | |
26 | #include <linux/unistd.h> | |
27 | #include <linux/stddef.h> | |
28 | #include <linux/tracehook.h> | |
29 | ||
30 | #include <asm/processor.h> | |
31 | #include <asm/ucontext.h> | |
32 | #include <asm/uaccess.h> | |
33 | ||
34 | #define DEBUG_SIG 0 | |
35 | ||
ac689eb7 JB |
36 | struct rt_sigframe { |
37 | struct siginfo *pinfo; | |
38 | void *puc; | |
39 | struct siginfo info; | |
40 | struct ucontext uc; | |
41 | unsigned char retcode[16]; /* trampoline code */ | |
42 | }; | |
43 | ||
44 | static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc) | |
45 | { | |
46 | unsigned int err = 0; | |
ac689eb7 JB |
47 | |
48 | /* Alwys make any pending restarted system call return -EINTR */ | |
49 | current_thread_info()->restart_block.fn = do_no_restart_syscall; | |
50 | ||
d7cb6667 JB |
51 | /* |
52 | * Restore the regs from &sc->regs. | |
ac689eb7 JB |
53 | * (sc is already checked for VERIFY_READ since the sigframe was |
54 | * checked in sys_sigreturn previously) | |
55 | */ | |
d7cb6667 JB |
56 | if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long))) |
57 | goto badframe; | |
58 | if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long))) | |
59 | goto badframe; | |
60 | if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long))) | |
ac689eb7 JB |
61 | goto badframe; |
62 | ||
63 | /* make sure the SM-bit is cleared so user-mode cannot fool us */ | |
64 | regs->sr &= ~SPR_SR_SM; | |
65 | ||
ac689eb7 JB |
66 | /* TODO: the other ports use regs->orig_XX to disable syscall checks |
67 | * after this completes, but we don't use that mechanism. maybe we can | |
68 | * use it now ? | |
69 | */ | |
70 | ||
71 | return err; | |
72 | ||
73 | badframe: | |
74 | return 1; | |
75 | } | |
76 | ||
77 | asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) | |
78 | { | |
79 | struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; | |
80 | sigset_t set; | |
ac689eb7 JB |
81 | |
82 | /* | |
83 | * Since we stacked the signal on a dword boundary, | |
84 | * then frame should be dword aligned here. If it's | |
85 | * not, then the user is trying to mess with us. | |
86 | */ | |
87 | if (((long)frame) & 3) | |
88 | goto badframe; | |
89 | ||
90 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) | |
91 | goto badframe; | |
92 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) | |
93 | goto badframe; | |
94 | ||
d8d4b20d | 95 | set_current_blocked(&set); |
ac689eb7 JB |
96 | |
97 | if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) | |
98 | goto badframe; | |
99 | ||
faec5a96 | 100 | if (restore_altstack(&frame->uc.uc_stack)) |
d26654e5 | 101 | goto badframe; |
ac689eb7 JB |
102 | |
103 | return regs->gpr[11]; | |
104 | ||
105 | badframe: | |
106 | force_sig(SIGSEGV, current); | |
107 | return 0; | |
108 | } | |
109 | ||
110 | /* | |
111 | * Set up a signal frame. | |
112 | */ | |
113 | ||
114 | static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, | |
115 | unsigned long mask) | |
116 | { | |
117 | int err = 0; | |
ac689eb7 | 118 | |
d7cb6667 | 119 | /* copy the regs */ |
ac689eb7 | 120 | |
d7cb6667 JB |
121 | err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); |
122 | err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); | |
123 | err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); | |
ac689eb7 JB |
124 | |
125 | /* then some other stuff */ | |
126 | ||
127 | err |= __put_user(mask, &sc->oldmask); | |
128 | ||
ac689eb7 JB |
129 | return err; |
130 | } | |
131 | ||
132 | static inline unsigned long align_sigframe(unsigned long sp) | |
133 | { | |
134 | return sp & ~3UL; | |
135 | } | |
136 | ||
137 | /* | |
138 | * Work out where the signal frame should go. It's either on the user stack | |
139 | * or the alternate stack. | |
140 | */ | |
141 | ||
142 | static inline void __user *get_sigframe(struct k_sigaction *ka, | |
143 | struct pt_regs *regs, size_t frame_size) | |
144 | { | |
145 | unsigned long sp = regs->sp; | |
146 | int onsigstack = on_sig_stack(sp); | |
147 | ||
148 | /* redzone */ | |
149 | sp -= STACK_FRAME_OVERHEAD; | |
150 | ||
151 | /* This is the X/Open sanctioned signal stack switching. */ | |
152 | if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { | |
153 | if (current->sas_ss_size) | |
154 | sp = current->sas_ss_sp + current->sas_ss_size; | |
155 | } | |
156 | ||
157 | sp = align_sigframe(sp - frame_size); | |
158 | ||
159 | /* | |
160 | * If we are on the alternate signal stack and would overflow it, don't. | |
161 | * Return an always-bogus address instead so we will die with SIGSEGV. | |
162 | */ | |
163 | if (onsigstack && !likely(on_sig_stack(sp))) | |
164 | return (void __user *)-1L; | |
165 | ||
166 | return (void __user *)sp; | |
167 | } | |
168 | ||
169 | /* grab and setup a signal frame. | |
170 | * | |
171 | * basically we stack a lot of state info, and arrange for the | |
172 | * user-mode program to return to the kernel using either a | |
173 | * trampoline which performs the syscall sigreturn, or a provided | |
174 | * user-mode trampoline. | |
175 | */ | |
e933c70d MF |
176 | static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, |
177 | sigset_t *set, struct pt_regs *regs) | |
ac689eb7 JB |
178 | { |
179 | struct rt_sigframe *frame; | |
180 | unsigned long return_ip; | |
181 | int err = 0; | |
182 | ||
183 | frame = get_sigframe(ka, regs, sizeof(*frame)); | |
184 | ||
185 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) | |
186 | goto give_sigsegv; | |
187 | ||
188 | err |= __put_user(&frame->info, &frame->pinfo); | |
189 | err |= __put_user(&frame->uc, &frame->puc); | |
190 | ||
191 | if (ka->sa.sa_flags & SA_SIGINFO) | |
192 | err |= copy_siginfo_to_user(&frame->info, info); | |
193 | if (err) | |
194 | goto give_sigsegv; | |
195 | ||
196 | /* Clear all the bits of the ucontext we don't use. */ | |
197 | err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); | |
198 | err |= __put_user(0, &frame->uc.uc_flags); | |
199 | err |= __put_user(NULL, &frame->uc.uc_link); | |
faec5a96 | 200 | err |= __save_altstack(&frame->uc.uc_stack, regs->sp); |
ac689eb7 JB |
201 | err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); |
202 | ||
203 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); | |
204 | ||
205 | if (err) | |
206 | goto give_sigsegv; | |
207 | ||
208 | /* trampoline - the desired return ip is the retcode itself */ | |
209 | return_ip = (unsigned long)&frame->retcode; | |
210 | /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */ | |
211 | err |= __put_user(0xa960, (short *)(frame->retcode + 0)); | |
212 | err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); | |
213 | err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); | |
214 | err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); | |
215 | ||
216 | if (err) | |
217 | goto give_sigsegv; | |
218 | ||
219 | /* TODO what is the current->exec_domain stuff and invmap ? */ | |
220 | ||
221 | /* Set up registers for signal handler */ | |
222 | regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ | |
223 | regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ | |
224 | regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */ | |
225 | regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ | |
226 | regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ | |
227 | ||
228 | /* actually move the usp to reflect the stacked frame */ | |
229 | regs->sp = (unsigned long)frame; | |
230 | ||
e933c70d | 231 | return 0; |
ac689eb7 JB |
232 | |
233 | give_sigsegv: | |
4ca159f7 | 234 | force_sigsegv(sig, current); |
e933c70d | 235 | return -EFAULT; |
ac689eb7 JB |
236 | } |
237 | ||
39974d08 | 238 | static inline void |
ac689eb7 JB |
239 | handle_signal(unsigned long sig, |
240 | siginfo_t *info, struct k_sigaction *ka, | |
b7f9a11a | 241 | struct pt_regs *regs) |
ac689eb7 | 242 | { |
e933c70d MF |
243 | int ret; |
244 | ||
b7f9a11a | 245 | ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs); |
e933c70d | 246 | if (ret) |
39974d08 | 247 | return; |
ac689eb7 | 248 | |
efee984c | 249 | signal_delivered(sig, info, ka, regs, |
39974d08 | 250 | test_thread_flag(TIF_SINGLESTEP)); |
ac689eb7 JB |
251 | } |
252 | ||
253 | /* | |
254 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
255 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
256 | * mistake. | |
257 | * | |
258 | * Also note that the regs structure given here as an argument, is the latest | |
259 | * pushed pt_regs. It may or may not be the same as the first pushed registers | |
260 | * when the initial usermode->kernelmode transition took place. Therefore | |
261 | * we can use user_mode(regs) to see if we came directly from kernel or user | |
262 | * mode below. | |
263 | */ | |
264 | ||
265 | void do_signal(struct pt_regs *regs) | |
266 | { | |
267 | siginfo_t info; | |
268 | int signr; | |
269 | struct k_sigaction ka; | |
270 | ||
271 | /* | |
272 | * We want the common case to go fast, which | |
273 | * is why we may in certain cases get here from | |
274 | * kernel mode. Just return without doing anything | |
275 | * if so. | |
276 | */ | |
277 | if (!user_mode(regs)) | |
278 | return; | |
279 | ||
280 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); | |
281 | ||
282 | /* If we are coming out of a syscall then we need | |
283 | * to check if the syscall was interrupted and wants to be | |
284 | * restarted after handling the signal. If so, the original | |
285 | * syscall number is put back into r11 and the PC rewound to | |
286 | * point at the l.sys instruction that resulted in the | |
287 | * original syscall. Syscall results other than the four | |
288 | * below mean that the syscall executed to completion and no | |
289 | * restart is necessary. | |
290 | */ | |
6cbe5e95 | 291 | if (regs->orig_gpr11) { |
ac689eb7 JB |
292 | int restart = 0; |
293 | ||
294 | switch (regs->gpr[11]) { | |
295 | case -ERESTART_RESTARTBLOCK: | |
296 | case -ERESTARTNOHAND: | |
297 | /* Restart if there is no signal handler */ | |
298 | restart = (signr <= 0); | |
299 | break; | |
300 | case -ERESTARTSYS: | |
301 | /* Restart if there no signal handler or | |
302 | * SA_RESTART flag is set */ | |
303 | restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); | |
304 | break; | |
305 | case -ERESTARTNOINTR: | |
306 | /* Always restart */ | |
307 | restart = 1; | |
308 | break; | |
309 | } | |
310 | ||
311 | if (restart) { | |
312 | if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) | |
313 | regs->gpr[11] = __NR_restart_syscall; | |
314 | else | |
315 | regs->gpr[11] = regs->orig_gpr11; | |
316 | regs->pc -= 4; | |
317 | } else { | |
318 | regs->gpr[11] = -EINTR; | |
319 | } | |
320 | } | |
321 | ||
322 | if (signr <= 0) { | |
323 | /* no signal to deliver so we just put the saved sigmask | |
324 | * back */ | |
51a7b448 | 325 | restore_saved_sigmask(); |
ac689eb7 | 326 | } else { /* signr > 0 */ |
ac689eb7 | 327 | /* Whee! Actually deliver the signal. */ |
39974d08 | 328 | handle_signal(signr, &info, &ka, regs); |
ac689eb7 JB |
329 | } |
330 | ||
331 | return; | |
332 | } | |
333 | ||
334 | asmlinkage void do_notify_resume(struct pt_regs *regs) | |
335 | { | |
336 | if (current_thread_info()->flags & _TIF_SIGPENDING) | |
337 | do_signal(regs); | |
338 | ||
339 | if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { | |
340 | clear_thread_flag(TIF_NOTIFY_RESUME); | |
341 | tracehook_notify_resume(regs); | |
ac689eb7 JB |
342 | } |
343 | } |