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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 | asmlinkage long |
37 | _sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs) | |
38 | { | |
39 | return do_sigaltstack(uss, uoss, regs->sp); | |
40 | } | |
41 | ||
42 | struct rt_sigframe { | |
43 | struct siginfo *pinfo; | |
44 | void *puc; | |
45 | struct siginfo info; | |
46 | struct ucontext uc; | |
47 | unsigned char retcode[16]; /* trampoline code */ | |
48 | }; | |
49 | ||
50 | static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc) | |
51 | { | |
52 | unsigned int err = 0; | |
ac689eb7 JB |
53 | |
54 | /* Alwys make any pending restarted system call return -EINTR */ | |
55 | current_thread_info()->restart_block.fn = do_no_restart_syscall; | |
56 | ||
d7cb6667 JB |
57 | /* |
58 | * Restore the regs from &sc->regs. | |
ac689eb7 JB |
59 | * (sc is already checked for VERIFY_READ since the sigframe was |
60 | * checked in sys_sigreturn previously) | |
61 | */ | |
d7cb6667 JB |
62 | if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long))) |
63 | goto badframe; | |
64 | if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long))) | |
65 | goto badframe; | |
66 | if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long))) | |
ac689eb7 JB |
67 | goto badframe; |
68 | ||
69 | /* make sure the SM-bit is cleared so user-mode cannot fool us */ | |
70 | regs->sr &= ~SPR_SR_SM; | |
71 | ||
ac689eb7 JB |
72 | /* TODO: the other ports use regs->orig_XX to disable syscall checks |
73 | * after this completes, but we don't use that mechanism. maybe we can | |
74 | * use it now ? | |
75 | */ | |
76 | ||
77 | return err; | |
78 | ||
79 | badframe: | |
80 | return 1; | |
81 | } | |
82 | ||
83 | asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) | |
84 | { | |
85 | struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; | |
86 | sigset_t set; | |
ac689eb7 JB |
87 | |
88 | /* | |
89 | * Since we stacked the signal on a dword boundary, | |
90 | * then frame should be dword aligned here. If it's | |
91 | * not, then the user is trying to mess with us. | |
92 | */ | |
93 | if (((long)frame) & 3) | |
94 | goto badframe; | |
95 | ||
96 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) | |
97 | goto badframe; | |
98 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) | |
99 | goto badframe; | |
100 | ||
d8d4b20d | 101 | set_current_blocked(&set); |
ac689eb7 JB |
102 | |
103 | if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) | |
104 | goto badframe; | |
105 | ||
ac689eb7 JB |
106 | /* It is more difficult to avoid calling this function than to |
107 | call it and ignore errors. */ | |
d26654e5 AV |
108 | if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) |
109 | goto badframe; | |
ac689eb7 JB |
110 | |
111 | return regs->gpr[11]; | |
112 | ||
113 | badframe: | |
114 | force_sig(SIGSEGV, current); | |
115 | return 0; | |
116 | } | |
117 | ||
118 | /* | |
119 | * Set up a signal frame. | |
120 | */ | |
121 | ||
122 | static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, | |
123 | unsigned long mask) | |
124 | { | |
125 | int err = 0; | |
ac689eb7 | 126 | |
d7cb6667 | 127 | /* copy the regs */ |
ac689eb7 | 128 | |
d7cb6667 JB |
129 | err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); |
130 | err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); | |
131 | err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); | |
ac689eb7 JB |
132 | |
133 | /* then some other stuff */ | |
134 | ||
135 | err |= __put_user(mask, &sc->oldmask); | |
136 | ||
ac689eb7 JB |
137 | return err; |
138 | } | |
139 | ||
140 | static inline unsigned long align_sigframe(unsigned long sp) | |
141 | { | |
142 | return sp & ~3UL; | |
143 | } | |
144 | ||
145 | /* | |
146 | * Work out where the signal frame should go. It's either on the user stack | |
147 | * or the alternate stack. | |
148 | */ | |
149 | ||
150 | static inline void __user *get_sigframe(struct k_sigaction *ka, | |
151 | struct pt_regs *regs, size_t frame_size) | |
152 | { | |
153 | unsigned long sp = regs->sp; | |
154 | int onsigstack = on_sig_stack(sp); | |
155 | ||
156 | /* redzone */ | |
157 | sp -= STACK_FRAME_OVERHEAD; | |
158 | ||
159 | /* This is the X/Open sanctioned signal stack switching. */ | |
160 | if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { | |
161 | if (current->sas_ss_size) | |
162 | sp = current->sas_ss_sp + current->sas_ss_size; | |
163 | } | |
164 | ||
165 | sp = align_sigframe(sp - frame_size); | |
166 | ||
167 | /* | |
168 | * If we are on the alternate signal stack and would overflow it, don't. | |
169 | * Return an always-bogus address instead so we will die with SIGSEGV. | |
170 | */ | |
171 | if (onsigstack && !likely(on_sig_stack(sp))) | |
172 | return (void __user *)-1L; | |
173 | ||
174 | return (void __user *)sp; | |
175 | } | |
176 | ||
177 | /* grab and setup a signal frame. | |
178 | * | |
179 | * basically we stack a lot of state info, and arrange for the | |
180 | * user-mode program to return to the kernel using either a | |
181 | * trampoline which performs the syscall sigreturn, or a provided | |
182 | * user-mode trampoline. | |
183 | */ | |
e933c70d MF |
184 | static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, |
185 | sigset_t *set, struct pt_regs *regs) | |
ac689eb7 JB |
186 | { |
187 | struct rt_sigframe *frame; | |
188 | unsigned long return_ip; | |
189 | int err = 0; | |
190 | ||
191 | frame = get_sigframe(ka, regs, sizeof(*frame)); | |
192 | ||
193 | if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) | |
194 | goto give_sigsegv; | |
195 | ||
196 | err |= __put_user(&frame->info, &frame->pinfo); | |
197 | err |= __put_user(&frame->uc, &frame->puc); | |
198 | ||
199 | if (ka->sa.sa_flags & SA_SIGINFO) | |
200 | err |= copy_siginfo_to_user(&frame->info, info); | |
201 | if (err) | |
202 | goto give_sigsegv; | |
203 | ||
204 | /* Clear all the bits of the ucontext we don't use. */ | |
205 | err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); | |
206 | err |= __put_user(0, &frame->uc.uc_flags); | |
207 | err |= __put_user(NULL, &frame->uc.uc_link); | |
208 | err |= __put_user((void *)current->sas_ss_sp, | |
209 | &frame->uc.uc_stack.ss_sp); | |
210 | err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); | |
211 | err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); | |
212 | err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); | |
213 | ||
214 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); | |
215 | ||
216 | if (err) | |
217 | goto give_sigsegv; | |
218 | ||
219 | /* trampoline - the desired return ip is the retcode itself */ | |
220 | return_ip = (unsigned long)&frame->retcode; | |
221 | /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */ | |
222 | err |= __put_user(0xa960, (short *)(frame->retcode + 0)); | |
223 | err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); | |
224 | err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); | |
225 | err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); | |
226 | ||
227 | if (err) | |
228 | goto give_sigsegv; | |
229 | ||
230 | /* TODO what is the current->exec_domain stuff and invmap ? */ | |
231 | ||
232 | /* Set up registers for signal handler */ | |
233 | regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ | |
234 | regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ | |
235 | regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */ | |
236 | regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ | |
237 | regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ | |
238 | ||
239 | /* actually move the usp to reflect the stacked frame */ | |
240 | regs->sp = (unsigned long)frame; | |
241 | ||
e933c70d | 242 | return 0; |
ac689eb7 JB |
243 | |
244 | give_sigsegv: | |
4ca159f7 | 245 | force_sigsegv(sig, current); |
e933c70d | 246 | return -EFAULT; |
ac689eb7 JB |
247 | } |
248 | ||
39974d08 | 249 | static inline void |
ac689eb7 JB |
250 | handle_signal(unsigned long sig, |
251 | siginfo_t *info, struct k_sigaction *ka, | |
b7f9a11a | 252 | struct pt_regs *regs) |
ac689eb7 | 253 | { |
e933c70d MF |
254 | int ret; |
255 | ||
b7f9a11a | 256 | ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs); |
e933c70d | 257 | if (ret) |
39974d08 | 258 | return; |
ac689eb7 | 259 | |
efee984c | 260 | signal_delivered(sig, info, ka, regs, |
39974d08 | 261 | test_thread_flag(TIF_SINGLESTEP)); |
ac689eb7 JB |
262 | } |
263 | ||
264 | /* | |
265 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
266 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
267 | * mistake. | |
268 | * | |
269 | * Also note that the regs structure given here as an argument, is the latest | |
270 | * pushed pt_regs. It may or may not be the same as the first pushed registers | |
271 | * when the initial usermode->kernelmode transition took place. Therefore | |
272 | * we can use user_mode(regs) to see if we came directly from kernel or user | |
273 | * mode below. | |
274 | */ | |
275 | ||
276 | void do_signal(struct pt_regs *regs) | |
277 | { | |
278 | siginfo_t info; | |
279 | int signr; | |
280 | struct k_sigaction ka; | |
281 | ||
282 | /* | |
283 | * We want the common case to go fast, which | |
284 | * is why we may in certain cases get here from | |
285 | * kernel mode. Just return without doing anything | |
286 | * if so. | |
287 | */ | |
288 | if (!user_mode(regs)) | |
289 | return; | |
290 | ||
291 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); | |
292 | ||
293 | /* If we are coming out of a syscall then we need | |
294 | * to check if the syscall was interrupted and wants to be | |
295 | * restarted after handling the signal. If so, the original | |
296 | * syscall number is put back into r11 and the PC rewound to | |
297 | * point at the l.sys instruction that resulted in the | |
298 | * original syscall. Syscall results other than the four | |
299 | * below mean that the syscall executed to completion and no | |
300 | * restart is necessary. | |
301 | */ | |
6cbe5e95 | 302 | if (regs->orig_gpr11) { |
ac689eb7 JB |
303 | int restart = 0; |
304 | ||
305 | switch (regs->gpr[11]) { | |
306 | case -ERESTART_RESTARTBLOCK: | |
307 | case -ERESTARTNOHAND: | |
308 | /* Restart if there is no signal handler */ | |
309 | restart = (signr <= 0); | |
310 | break; | |
311 | case -ERESTARTSYS: | |
312 | /* Restart if there no signal handler or | |
313 | * SA_RESTART flag is set */ | |
314 | restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); | |
315 | break; | |
316 | case -ERESTARTNOINTR: | |
317 | /* Always restart */ | |
318 | restart = 1; | |
319 | break; | |
320 | } | |
321 | ||
322 | if (restart) { | |
323 | if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) | |
324 | regs->gpr[11] = __NR_restart_syscall; | |
325 | else | |
326 | regs->gpr[11] = regs->orig_gpr11; | |
327 | regs->pc -= 4; | |
328 | } else { | |
329 | regs->gpr[11] = -EINTR; | |
330 | } | |
331 | } | |
332 | ||
333 | if (signr <= 0) { | |
334 | /* no signal to deliver so we just put the saved sigmask | |
335 | * back */ | |
51a7b448 | 336 | restore_saved_sigmask(); |
ac689eb7 | 337 | } else { /* signr > 0 */ |
ac689eb7 | 338 | /* Whee! Actually deliver the signal. */ |
39974d08 | 339 | handle_signal(signr, &info, &ka, regs); |
ac689eb7 JB |
340 | } |
341 | ||
342 | return; | |
343 | } | |
344 | ||
345 | asmlinkage void do_notify_resume(struct pt_regs *regs) | |
346 | { | |
347 | if (current_thread_info()->flags & _TIF_SIGPENDING) | |
348 | do_signal(regs); | |
349 | ||
350 | if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { | |
351 | clear_thread_flag(TIF_NOTIFY_RESUME); | |
352 | tracehook_notify_resume(regs); | |
ac689eb7 JB |
353 | } |
354 | } |