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
36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
37
38 asmlinkage long
_sys_sigaltstack(const stack_t * uss,stack_t * uoss,struct pt_regs * regs)39 _sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs)
40 {
41 return do_sigaltstack(uss, uoss, regs->sp);
42 }
43
44 struct rt_sigframe {
45 struct siginfo *pinfo;
46 void *puc;
47 struct siginfo info;
48 struct ucontext uc;
49 unsigned char retcode[16]; /* trampoline code */
50 };
51
restore_sigcontext(struct pt_regs * regs,struct sigcontext * sc)52 static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
53 {
54 unsigned int err = 0;
55
56 /* Alwys make any pending restarted system call return -EINTR */
57 current_thread_info()->restart_block.fn = do_no_restart_syscall;
58
59 /*
60 * Restore the regs from &sc->regs.
61 * (sc is already checked for VERIFY_READ since the sigframe was
62 * checked in sys_sigreturn previously)
63 */
64 if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)))
65 goto badframe;
66 if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)))
67 goto badframe;
68 if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)))
69 goto badframe;
70
71 /* make sure the SM-bit is cleared so user-mode cannot fool us */
72 regs->sr &= ~SPR_SR_SM;
73
74 /* TODO: the other ports use regs->orig_XX to disable syscall checks
75 * after this completes, but we don't use that mechanism. maybe we can
76 * use it now ?
77 */
78
79 return err;
80
81 badframe:
82 return 1;
83 }
84
_sys_rt_sigreturn(struct pt_regs * regs)85 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
86 {
87 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
88 sigset_t set;
89 stack_t st;
90
91 /*
92 * Since we stacked the signal on a dword boundary,
93 * then frame should be dword aligned here. If it's
94 * not, then the user is trying to mess with us.
95 */
96 if (((long)frame) & 3)
97 goto badframe;
98
99 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
100 goto badframe;
101 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
102 goto badframe;
103
104 sigdelsetmask(&set, ~_BLOCKABLE);
105 set_current_blocked(&set);
106
107 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
108 goto badframe;
109
110 if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
111 goto badframe;
112 /* It is more difficult to avoid calling this function than to
113 call it and ignore errors. */
114 do_sigaltstack(&st, NULL, regs->sp);
115
116 return regs->gpr[11];
117
118 badframe:
119 force_sig(SIGSEGV, current);
120 return 0;
121 }
122
123 /*
124 * Set up a signal frame.
125 */
126
setup_sigcontext(struct sigcontext * sc,struct pt_regs * regs,unsigned long mask)127 static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
128 unsigned long mask)
129 {
130 int err = 0;
131
132 /* copy the regs */
133
134 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
135 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
136 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
137
138 /* then some other stuff */
139
140 err |= __put_user(mask, &sc->oldmask);
141
142 return err;
143 }
144
align_sigframe(unsigned long sp)145 static inline unsigned long align_sigframe(unsigned long sp)
146 {
147 return sp & ~3UL;
148 }
149
150 /*
151 * Work out where the signal frame should go. It's either on the user stack
152 * or the alternate stack.
153 */
154
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size)155 static inline void __user *get_sigframe(struct k_sigaction *ka,
156 struct pt_regs *regs, size_t frame_size)
157 {
158 unsigned long sp = regs->sp;
159 int onsigstack = on_sig_stack(sp);
160
161 /* redzone */
162 sp -= STACK_FRAME_OVERHEAD;
163
164 /* This is the X/Open sanctioned signal stack switching. */
165 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) {
166 if (current->sas_ss_size)
167 sp = current->sas_ss_sp + current->sas_ss_size;
168 }
169
170 sp = align_sigframe(sp - frame_size);
171
172 /*
173 * If we are on the alternate signal stack and would overflow it, don't.
174 * Return an always-bogus address instead so we will die with SIGSEGV.
175 */
176 if (onsigstack && !likely(on_sig_stack(sp)))
177 return (void __user *)-1L;
178
179 return (void __user *)sp;
180 }
181
182 /* grab and setup a signal frame.
183 *
184 * basically we stack a lot of state info, and arrange for the
185 * user-mode program to return to the kernel using either a
186 * trampoline which performs the syscall sigreturn, or a provided
187 * user-mode trampoline.
188 */
setup_rt_frame(int sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)189 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
190 sigset_t *set, struct pt_regs *regs)
191 {
192 struct rt_sigframe *frame;
193 unsigned long return_ip;
194 int err = 0;
195
196 frame = get_sigframe(ka, regs, sizeof(*frame));
197
198 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
199 goto give_sigsegv;
200
201 err |= __put_user(&frame->info, &frame->pinfo);
202 err |= __put_user(&frame->uc, &frame->puc);
203
204 if (ka->sa.sa_flags & SA_SIGINFO)
205 err |= copy_siginfo_to_user(&frame->info, info);
206 if (err)
207 goto give_sigsegv;
208
209 /* Clear all the bits of the ucontext we don't use. */
210 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
211 err |= __put_user(0, &frame->uc.uc_flags);
212 err |= __put_user(NULL, &frame->uc.uc_link);
213 err |= __put_user((void *)current->sas_ss_sp,
214 &frame->uc.uc_stack.ss_sp);
215 err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags);
216 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
217 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
218
219 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
220
221 if (err)
222 goto give_sigsegv;
223
224 /* trampoline - the desired return ip is the retcode itself */
225 return_ip = (unsigned long)&frame->retcode;
226 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
227 err |= __put_user(0xa960, (short *)(frame->retcode + 0));
228 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
229 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
230 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
231
232 if (err)
233 goto give_sigsegv;
234
235 /* TODO what is the current->exec_domain stuff and invmap ? */
236
237 /* Set up registers for signal handler */
238 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */
239 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
240 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */
241 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
242 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
243
244 /* actually move the usp to reflect the stacked frame */
245 regs->sp = (unsigned long)frame;
246
247 return 0;
248
249 give_sigsegv:
250 force_sigsegv(sig, current);
251 return -EFAULT;
252 }
253
254 static inline int
handle_signal(unsigned long sig,siginfo_t * info,struct k_sigaction * ka,sigset_t * oldset,struct pt_regs * regs)255 handle_signal(unsigned long sig,
256 siginfo_t *info, struct k_sigaction *ka,
257 sigset_t *oldset, struct pt_regs *regs)
258 {
259 int ret;
260
261 ret = setup_rt_frame(sig, ka, info, oldset, regs);
262 if (ret)
263 return ret;
264
265 block_sigmask(ka, sig);
266
267 return 0;
268 }
269
270 /*
271 * Note that 'init' is a special process: it doesn't get signals it doesn't
272 * want to handle. Thus you cannot kill init even with a SIGKILL even by
273 * mistake.
274 *
275 * Also note that the regs structure given here as an argument, is the latest
276 * pushed pt_regs. It may or may not be the same as the first pushed registers
277 * when the initial usermode->kernelmode transition took place. Therefore
278 * we can use user_mode(regs) to see if we came directly from kernel or user
279 * mode below.
280 */
281
do_signal(struct pt_regs * regs)282 void do_signal(struct pt_regs *regs)
283 {
284 siginfo_t info;
285 int signr;
286 struct k_sigaction ka;
287
288 /*
289 * We want the common case to go fast, which
290 * is why we may in certain cases get here from
291 * kernel mode. Just return without doing anything
292 * if so.
293 */
294 if (!user_mode(regs))
295 return;
296
297 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
298
299 /* If we are coming out of a syscall then we need
300 * to check if the syscall was interrupted and wants to be
301 * restarted after handling the signal. If so, the original
302 * syscall number is put back into r11 and the PC rewound to
303 * point at the l.sys instruction that resulted in the
304 * original syscall. Syscall results other than the four
305 * below mean that the syscall executed to completion and no
306 * restart is necessary.
307 */
308 if (regs->orig_gpr11) {
309 int restart = 0;
310
311 switch (regs->gpr[11]) {
312 case -ERESTART_RESTARTBLOCK:
313 case -ERESTARTNOHAND:
314 /* Restart if there is no signal handler */
315 restart = (signr <= 0);
316 break;
317 case -ERESTARTSYS:
318 /* Restart if there no signal handler or
319 * SA_RESTART flag is set */
320 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
321 break;
322 case -ERESTARTNOINTR:
323 /* Always restart */
324 restart = 1;
325 break;
326 }
327
328 if (restart) {
329 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
330 regs->gpr[11] = __NR_restart_syscall;
331 else
332 regs->gpr[11] = regs->orig_gpr11;
333 regs->pc -= 4;
334 } else {
335 regs->gpr[11] = -EINTR;
336 }
337 }
338
339 if (signr <= 0) {
340 /* no signal to deliver so we just put the saved sigmask
341 * back */
342 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
343 clear_thread_flag(TIF_RESTORE_SIGMASK);
344 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
345 }
346
347 } else { /* signr > 0 */
348 sigset_t *oldset;
349
350 if (current_thread_info()->flags & _TIF_RESTORE_SIGMASK)
351 oldset = ¤t->saved_sigmask;
352 else
353 oldset = ¤t->blocked;
354
355 /* Whee! Actually deliver the signal. */
356 if (!handle_signal(signr, &info, &ka, oldset, regs)) {
357 /* a signal was successfully delivered; the saved
358 * sigmask will have been stored in the signal frame,
359 * and will be restored by sigreturn, so we can simply
360 * clear the TIF_RESTORE_SIGMASK flag */
361 clear_thread_flag(TIF_RESTORE_SIGMASK);
362 }
363
364 tracehook_signal_handler(signr, &info, &ka, regs,
365 test_thread_flag(TIF_SINGLESTEP));
366 }
367
368 return;
369 }
370
do_notify_resume(struct pt_regs * regs)371 asmlinkage void do_notify_resume(struct pt_regs *regs)
372 {
373 if (current_thread_info()->flags & _TIF_SIGPENDING)
374 do_signal(regs);
375
376 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
377 clear_thread_flag(TIF_NOTIFY_RESUME);
378 tracehook_notify_resume(regs);
379 if (current->replacement_session_keyring)
380 key_replace_session_keyring();
381 }
382 }
383