1 /*
2 * Copyright (C) 2003, Axis Communications AB.
3 */
4
5 #include <linux/sched.h>
6 #include <linux/mm.h>
7 #include <linux/slab.h>
8 #include <linux/kernel.h>
9 #include <linux/signal.h>
10 #include <linux/errno.h>
11 #include <linux/wait.h>
12 #include <linux/ptrace.h>
13 #include <linux/unistd.h>
14 #include <linux/stddef.h>
15 #include <linux/syscalls.h>
16 #include <linux/vmalloc.h>
17
18 #include <asm/io.h>
19 #include <asm/processor.h>
20 #include <asm/ucontext.h>
21 #include <asm/uaccess.h>
22 #include <arch/ptrace.h>
23 #include <arch/hwregs/cpu_vect.h>
24
25 extern unsigned long cris_signal_return_page;
26
27 /*
28 * A syscall in CRIS is really a "break 13" instruction, which is 2
29 * bytes. The registers is manipulated so upon return the instruction
30 * will be executed again.
31 *
32 * This relies on that PC points to the instruction after the break call.
33 */
34 #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;
35
36 /* Signal frames. */
37 struct signal_frame {
38 struct sigcontext sc;
39 unsigned long extramask[_NSIG_WORDS - 1];
40 unsigned char retcode[8]; /* Trampoline code. */
41 };
42
43 struct rt_signal_frame {
44 struct siginfo *pinfo;
45 void *puc;
46 struct siginfo info;
47 struct ucontext uc;
48 unsigned char retcode[8]; /* Trampoline code. */
49 };
50
51 void do_signal(int restart, struct pt_regs *regs);
52 void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
53 struct pt_regs *regs);
54
55 static int
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)56 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
57 {
58 unsigned int err = 0;
59 unsigned long old_usp;
60
61 /* Always make any pending restarted system calls return -EINTR */
62 current->restart_block.fn = do_no_restart_syscall;
63
64 /*
65 * Restore the registers from &sc->regs. sc is already checked
66 * for VERIFY_READ since the signal_frame was previously
67 * checked in sys_sigreturn().
68 */
69 if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
70 goto badframe;
71
72 /* Make that the user-mode flag is set. */
73 regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));
74
75 /* Restore the old USP. */
76 err |= __get_user(old_usp, &sc->usp);
77 wrusp(old_usp);
78
79 return err;
80
81 badframe:
82 return 1;
83 }
84
sys_sigreturn(void)85 asmlinkage int sys_sigreturn(void)
86 {
87 struct pt_regs *regs = current_pt_regs();
88 sigset_t set;
89 struct signal_frame __user *frame;
90 unsigned long oldspc = regs->spc;
91 unsigned long oldccs = regs->ccs;
92
93 frame = (struct signal_frame *) rdusp();
94
95 /*
96 * Since the signal is stacked on a dword boundary, the frame
97 * should be dword aligned here as well. It it's not, then the
98 * user is trying some funny business.
99 */
100 if (((long)frame) & 3)
101 goto badframe;
102
103 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
104 goto badframe;
105
106 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
107 (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
108 frame->extramask,
109 sizeof(frame->extramask))))
110 goto badframe;
111
112 set_current_blocked(&set);
113
114 if (restore_sigcontext(regs, &frame->sc))
115 goto badframe;
116
117 keep_debug_flags(oldccs, oldspc, regs);
118
119 return regs->r10;
120
121 badframe:
122 force_sig(SIGSEGV, current);
123 return 0;
124 }
125
sys_rt_sigreturn(void)126 asmlinkage int sys_rt_sigreturn(void)
127 {
128 struct pt_regs *regs = current_pt_regs();
129 sigset_t set;
130 struct rt_signal_frame __user *frame;
131 unsigned long oldspc = regs->spc;
132 unsigned long oldccs = regs->ccs;
133
134 frame = (struct rt_signal_frame *) rdusp();
135
136 /*
137 * Since the signal is stacked on a dword boundary, the frame
138 * should be dword aligned here as well. It it's not, then the
139 * user is trying some funny business.
140 */
141 if (((long)frame) & 3)
142 goto badframe;
143
144 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
145 goto badframe;
146
147 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
148 goto badframe;
149
150 set_current_blocked(&set);
151
152 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
153 goto badframe;
154
155 if (restore_altstack(&frame->uc.uc_stack))
156 goto badframe;
157
158 keep_debug_flags(oldccs, oldspc, regs);
159
160 return regs->r10;
161
162 badframe:
163 force_sig(SIGSEGV, current);
164 return 0;
165 }
166
167 /* Setup a signal frame. */
168 static int
setup_sigcontext(struct sigcontext __user * sc,struct pt_regs * regs,unsigned long mask)169 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
170 unsigned long mask)
171 {
172 int err;
173 unsigned long usp;
174
175 err = 0;
176 usp = rdusp();
177
178 /*
179 * Copy the registers. They are located first in sc, so it's
180 * possible to use sc directly.
181 */
182 err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
183
184 err |= __put_user(mask, &sc->oldmask);
185 err |= __put_user(usp, &sc->usp);
186
187 return err;
188 }
189
190 /* Figure out where to put the new signal frame - usually on the stack. */
191 static inline void __user *
get_sigframe(struct ksignal * ksig,size_t frame_size)192 get_sigframe(struct ksignal *ksig, size_t frame_size)
193 {
194 unsigned long sp = sigsp(rdusp(), ksig);
195
196 /* Make sure the frame is dword-aligned. */
197 sp &= ~3;
198
199 return (void __user *)(sp - frame_size);
200 }
201
202 /* Grab and setup a signal frame.
203 *
204 * Basically a lot of state-info is stacked, and arranged for the
205 * user-mode program to return to the kernel using either a trampiline
206 * which performs the syscall sigreturn(), or a provided user-mode
207 * trampoline.
208 */
209 static int
setup_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)210 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
211 {
212 int err;
213 unsigned long return_ip;
214 struct signal_frame __user *frame;
215
216 err = 0;
217 frame = get_sigframe(ksig, sizeof(*frame));
218
219 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
220 return -EFAULT;
221
222 err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
223
224 if (err)
225 return -EFAULT;
226
227 if (_NSIG_WORDS > 1) {
228 err |= __copy_to_user(frame->extramask, &set->sig[1],
229 sizeof(frame->extramask));
230 }
231
232 if (err)
233 return -EFAULT;
234
235 /*
236 * Set up to return from user-space. If provided, use a stub
237 * already located in user-space.
238 */
239 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
240 return_ip = (unsigned long)ksig->ka.sa.sa_restorer;
241 } else {
242 /* Trampoline - the desired return ip is in the signal return page. */
243 return_ip = cris_signal_return_page;
244
245 /*
246 * This is movu.w __NR_sigreturn, r9; break 13;
247 *
248 * WE DO NOT USE IT ANY MORE! It's only left here for historical
249 * reasons and because gdb uses it as a signature to notice
250 * signal handler stack frames.
251 */
252 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
253 err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
254 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
255 }
256
257 if (err)
258 return -EFAULT;
259
260 /*
261 * Set up registers for signal handler.
262 *
263 * Where the code enters now.
264 * Where the code enter later.
265 * First argument, signo.
266 */
267 regs->erp = (unsigned long) ksig->ka.sa.sa_handler;
268 regs->srp = return_ip;
269 regs->r10 = ksig->sig;
270
271 /* Actually move the USP to reflect the stacked frame. */
272 wrusp((unsigned long)frame);
273
274 return 0;
275 }
276
277 static int
setup_rt_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)278 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
279 {
280 int err;
281 unsigned long return_ip;
282 struct rt_signal_frame __user *frame;
283
284 err = 0;
285 frame = get_sigframe(ksig, sizeof(*frame));
286
287 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
288 return -EFAULT;
289
290 /* TODO: what is the current->exec_domain stuff and invmap ? */
291
292 err |= __put_user(&frame->info, &frame->pinfo);
293 err |= __put_user(&frame->uc, &frame->puc);
294 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
295
296 if (err)
297 return -EFAULT;
298
299 /* Clear all the bits of the ucontext we don't use. */
300 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
301 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
302 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
303 err |= __save_altstack(&frame->uc.uc_stack, rdusp());
304
305 if (err)
306 return -EFAULT;
307
308 /*
309 * Set up to return from user-space. If provided, use a stub
310 * already located in user-space.
311 */
312 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
313 return_ip = (unsigned long) ksig->ka.sa.sa_restorer;
314 } else {
315 /* Trampoline - the desired return ip is in the signal return page. */
316 return_ip = cris_signal_return_page + 6;
317
318 /*
319 * This is movu.w __NR_rt_sigreturn, r9; break 13;
320 *
321 * WE DO NOT USE IT ANY MORE! It's only left here for historical
322 * reasons and because gdb uses it as a signature to notice
323 * signal handler stack frames.
324 */
325 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
326
327 err |= __put_user(__NR_rt_sigreturn,
328 (short __user*)(frame->retcode+2));
329
330 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
331 }
332
333 if (err)
334 return -EFAULT;
335
336 /*
337 * Set up registers for signal handler.
338 *
339 * Where the code enters now.
340 * Where the code enters later.
341 * First argument is signo.
342 * Second argument is (siginfo_t *).
343 * Third argument is unused.
344 */
345 regs->erp = (unsigned long) ksig->ka.sa.sa_handler;
346 regs->srp = return_ip;
347 regs->r10 = ksig->sig;
348 regs->r11 = (unsigned long) &frame->info;
349 regs->r12 = 0;
350
351 /* Actually move the usp to reflect the stacked frame. */
352 wrusp((unsigned long)frame);
353
354 return 0;
355 }
356
357 /* Invoke a signal handler to, well, handle the signal. */
358 static inline void
handle_signal(int canrestart,struct ksignal * ksig,struct pt_regs * regs)359 handle_signal(int canrestart, struct ksignal *ksig, struct pt_regs *regs)
360 {
361 sigset_t *oldset = sigmask_to_save();
362 int ret;
363
364 /* Check if this got called from a system call. */
365 if (canrestart) {
366 /* If so, check system call restarting. */
367 switch (regs->r10) {
368 case -ERESTART_RESTARTBLOCK:
369 case -ERESTARTNOHAND:
370 /*
371 * This means that the syscall should
372 * only be restarted if there was no
373 * handler for the signal, and since
374 * this point isn't reached unless
375 * there is a handler, there's no need
376 * to restart.
377 */
378 regs->r10 = -EINTR;
379 break;
380
381 case -ERESTARTSYS:
382 /*
383 * This means restart the syscall if
384 * there is no handler, or the handler
385 * was registered with SA_RESTART.
386 */
387 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
388 regs->r10 = -EINTR;
389 break;
390 }
391
392 /* Fall through. */
393
394 case -ERESTARTNOINTR:
395 /*
396 * This means that the syscall should
397 * be called again after the signal
398 * handler returns.
399 */
400 RESTART_CRIS_SYS(regs);
401 break;
402 }
403 }
404
405 /* Set up the stack frame. */
406 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
407 ret = setup_rt_frame(ksig, oldset, regs);
408 else
409 ret = setup_frame(ksig, oldset, regs);
410
411 signal_setup_done(ret, ksig, 0);
412 }
413
414 /*
415 * Note that 'init' is a special process: it doesn't get signals it doesn't
416 * want to handle. Thus you cannot kill init even with a SIGKILL even by
417 * mistake.
418 *
419 * Also note that the regs structure given here as an argument, is the latest
420 * pushed pt_regs. It may or may not be the same as the first pushed registers
421 * when the initial usermode->kernelmode transition took place. Therefore
422 * we can use user_mode(regs) to see if we came directly from kernel or user
423 * mode below.
424 */
425 void
do_signal(int canrestart,struct pt_regs * regs)426 do_signal(int canrestart, struct pt_regs *regs)
427 {
428 struct ksignal ksig;
429
430 /*
431 * The common case should go fast, which is why this point is
432 * reached from kernel-mode. If that's the case, just return
433 * without doing anything.
434 */
435 if (!user_mode(regs))
436 return;
437
438 if (get_signal(&ksig)) {
439 /* Whee! Actually deliver the signal. */
440 handle_signal(canrestart, &ksig, regs);
441 return;
442 }
443
444 /* Got here from a system call? */
445 if (canrestart) {
446 /* Restart the system call - no handlers present. */
447 if (regs->r10 == -ERESTARTNOHAND ||
448 regs->r10 == -ERESTARTSYS ||
449 regs->r10 == -ERESTARTNOINTR) {
450 RESTART_CRIS_SYS(regs);
451 }
452
453 if (regs->r10 == -ERESTART_RESTARTBLOCK){
454 regs->r9 = __NR_restart_syscall;
455 regs->erp -= 2;
456 }
457 }
458
459 /* if there's no signal to deliver, we just put the saved sigmask
460 * back */
461 restore_saved_sigmask();
462 }
463
464 asmlinkage void
ugdb_trap_user(struct thread_info * ti,int sig)465 ugdb_trap_user(struct thread_info *ti, int sig)
466 {
467 if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
468 /* Zero single-step PC if the reason we stopped wasn't a single
469 step exception. This is to avoid relying on it when it isn't
470 reliable. */
471 user_regs(ti)->spc = 0;
472 }
473 /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
474 not within any configured h/w breakpoint range). Synchronize with
475 what already exists for kernel debugging. */
476 if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
477 /* Break 8: subtract 2 from ERP unless in a delay slot. */
478 if (!(user_regs(ti)->erp & 0x1))
479 user_regs(ti)->erp -= 2;
480 }
481 sys_kill(ti->task->pid, sig);
482 }
483
484 void
keep_debug_flags(unsigned long oldccs,unsigned long oldspc,struct pt_regs * regs)485 keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
486 struct pt_regs *regs)
487 {
488 if (oldccs & (1 << Q_CCS_BITNR)) {
489 /* Pending single step due to single-stepping the break 13
490 in the signal trampoline: keep the Q flag. */
491 regs->ccs |= (1 << Q_CCS_BITNR);
492 /* S flag should be set - complain if it's not. */
493 if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
494 printk("Q flag but no S flag?");
495 }
496 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
497 /* Assume the SPC is valid and interesting. */
498 regs->spc = oldspc;
499
500 } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
501 /* If a h/w bp was set in the signal handler we need
502 to keep the S flag. */
503 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
504 /* Don't keep the old SPC though; if we got here due to
505 a single-step, the Q flag should have been set. */
506 } else if (regs->spc) {
507 /* If we were single-stepping *before* the signal was taken,
508 we don't want to restore that state now, because GDB will
509 have forgotten all about it. */
510 regs->spc = 0;
511 regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
512 }
513 }
514
515 /* Set up the trampolines on the signal return page. */
516 int __init
cris_init_signal(void)517 cris_init_signal(void)
518 {
519 u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);
520
521 /* This is movu.w __NR_sigreturn, r9; break 13; */
522 data[0] = 0x9c5f;
523 data[1] = __NR_sigreturn;
524 data[2] = 0xe93d;
525 /* This is movu.w __NR_rt_sigreturn, r9; break 13; */
526 data[3] = 0x9c5f;
527 data[4] = __NR_rt_sigreturn;
528 data[5] = 0xe93d;
529
530 /* Map to userspace with appropriate permissions (no write access...) */
531 cris_signal_return_page = (unsigned long)
532 __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);
533
534 return 0;
535 }
536
537 __initcall(cris_init_signal);
538