1 /*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation, version 2.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
12 * NON INFRINGEMENT. See the GNU General Public License for
13 * more details.
14 */
15
16 #include <linux/sched.h>
17 #include <linux/mm.h>
18 #include <linux/smp.h>
19 #include <linux/kernel.h>
20 #include <linux/signal.h>
21 #include <linux/errno.h>
22 #include <linux/wait.h>
23 #include <linux/unistd.h>
24 #include <linux/stddef.h>
25 #include <linux/personality.h>
26 #include <linux/suspend.h>
27 #include <linux/ptrace.h>
28 #include <linux/elf.h>
29 #include <linux/compat.h>
30 #include <linux/syscalls.h>
31 #include <linux/uaccess.h>
32 #include <asm/processor.h>
33 #include <asm/ucontext.h>
34 #include <asm/sigframe.h>
35 #include <asm/syscalls.h>
36 #include <arch/interrupts.h>
37
38 #define DEBUG_SIG 0
39
40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
41
SYSCALL_DEFINE3(sigaltstack,const stack_t __user *,uss,stack_t __user *,uoss,struct pt_regs *,regs)42 SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss,
43 stack_t __user *, uoss, struct pt_regs *, regs)
44 {
45 return do_sigaltstack(uss, uoss, regs->sp);
46 }
47
48
49 /*
50 * Do a signal return; undo the signal stack.
51 */
52
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)53 int restore_sigcontext(struct pt_regs *regs,
54 struct sigcontext __user *sc)
55 {
56 int err = 0;
57 int i;
58
59 /* Always make any pending restarted system calls return -EINTR */
60 current_thread_info()->restart_block.fn = do_no_restart_syscall;
61
62 /*
63 * Enforce that sigcontext is like pt_regs, and doesn't mess
64 * up our stack alignment rules.
65 */
66 BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
67 BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
68
69 for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
70 err |= __get_user(regs->regs[i], &sc->gregs[i]);
71
72 /* Ensure that the PL is always set to USER_PL. */
73 regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
74
75 regs->faultnum = INT_SWINT_1_SIGRETURN;
76
77 return err;
78 }
79
signal_fault(const char * type,struct pt_regs * regs,void __user * frame,int sig)80 void signal_fault(const char *type, struct pt_regs *regs,
81 void __user *frame, int sig)
82 {
83 trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
84 force_sigsegv(sig, current);
85 }
86
87 /* The assembly shim for this function arranges to ignore the return value. */
SYSCALL_DEFINE1(rt_sigreturn,struct pt_regs *,regs)88 SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs)
89 {
90 struct rt_sigframe __user *frame =
91 (struct rt_sigframe __user *)(regs->sp);
92 sigset_t set;
93
94 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
95 goto badframe;
96 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
97 goto badframe;
98
99 sigdelsetmask(&set, ~_BLOCKABLE);
100 set_current_blocked(&set);
101
102 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
103 goto badframe;
104
105 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
106 goto badframe;
107
108 return 0;
109
110 badframe:
111 signal_fault("bad sigreturn frame", regs, frame, 0);
112 return 0;
113 }
114
115 /*
116 * Set up a signal frame.
117 */
118
setup_sigcontext(struct sigcontext __user * sc,struct pt_regs * regs)119 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
120 {
121 int i, err = 0;
122
123 for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
124 err |= __put_user(regs->regs[i], &sc->gregs[i]);
125
126 return err;
127 }
128
129 /*
130 * Determine which stack to use..
131 */
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size)132 static inline void __user *get_sigframe(struct k_sigaction *ka,
133 struct pt_regs *regs,
134 size_t frame_size)
135 {
136 unsigned long sp;
137
138 /* Default to using normal stack */
139 sp = regs->sp;
140
141 /*
142 * If we are on the alternate signal stack and would overflow
143 * it, don't. Return an always-bogus address instead so we
144 * will die with SIGSEGV.
145 */
146 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
147 return (void __user __force *)-1UL;
148
149 /* This is the X/Open sanctioned signal stack switching. */
150 if (ka->sa.sa_flags & SA_ONSTACK) {
151 if (sas_ss_flags(sp) == 0)
152 sp = current->sas_ss_sp + current->sas_ss_size;
153 }
154
155 sp -= frame_size;
156 /*
157 * Align the stack pointer according to the TILE ABI,
158 * i.e. so that on function entry (sp & 15) == 0.
159 */
160 sp &= -16UL;
161 return (void __user *) sp;
162 }
163
setup_rt_frame(int sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)164 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
165 sigset_t *set, struct pt_regs *regs)
166 {
167 unsigned long restorer;
168 struct rt_sigframe __user *frame;
169 int err = 0;
170 int usig;
171
172 frame = get_sigframe(ka, regs, sizeof(*frame));
173
174 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
175 goto give_sigsegv;
176
177 usig = current_thread_info()->exec_domain
178 && current_thread_info()->exec_domain->signal_invmap
179 && sig < 32
180 ? current_thread_info()->exec_domain->signal_invmap[sig]
181 : sig;
182
183 /* Always write at least the signal number for the stack backtracer. */
184 if (ka->sa.sa_flags & SA_SIGINFO) {
185 /* At sigreturn time, restore the callee-save registers too. */
186 err |= copy_siginfo_to_user(&frame->info, info);
187 regs->flags |= PT_FLAGS_RESTORE_REGS;
188 } else {
189 err |= __put_user(info->si_signo, &frame->info.si_signo);
190 }
191
192 /* Create the ucontext. */
193 err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
194 err |= __put_user(0, &frame->uc.uc_flags);
195 err |= __put_user(NULL, &frame->uc.uc_link);
196 err |= __put_user((void __user *)(current->sas_ss_sp),
197 &frame->uc.uc_stack.ss_sp);
198 err |= __put_user(sas_ss_flags(regs->sp),
199 &frame->uc.uc_stack.ss_flags);
200 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
201 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
202 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
203 if (err)
204 goto give_sigsegv;
205
206 restorer = VDSO_BASE;
207 if (ka->sa.sa_flags & SA_RESTORER)
208 restorer = (unsigned long) ka->sa.sa_restorer;
209
210 /*
211 * Set up registers for signal handler.
212 * Registers that we don't modify keep the value they had from
213 * user-space at the time we took the signal.
214 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
215 * since some things rely on this (e.g. glibc's debug/segfault.c).
216 */
217 regs->pc = (unsigned long) ka->sa.sa_handler;
218 regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
219 regs->sp = (unsigned long) frame;
220 regs->lr = restorer;
221 regs->regs[0] = (unsigned long) usig;
222 regs->regs[1] = (unsigned long) &frame->info;
223 regs->regs[2] = (unsigned long) &frame->uc;
224 regs->flags |= PT_FLAGS_CALLER_SAVES;
225
226 /*
227 * Notify any tracer that was single-stepping it.
228 * The tracer may want to single-step inside the
229 * handler too.
230 */
231 if (test_thread_flag(TIF_SINGLESTEP))
232 ptrace_notify(SIGTRAP);
233
234 return 0;
235
236 give_sigsegv:
237 signal_fault("bad setup frame", regs, frame, sig);
238 return -EFAULT;
239 }
240
241 /*
242 * OK, we're invoking a handler
243 */
244
handle_signal(unsigned long sig,siginfo_t * info,struct k_sigaction * ka,sigset_t * oldset,struct pt_regs * regs)245 static int handle_signal(unsigned long sig, siginfo_t *info,
246 struct k_sigaction *ka, sigset_t *oldset,
247 struct pt_regs *regs)
248 {
249 int ret;
250
251 /* Are we from a system call? */
252 if (regs->faultnum == INT_SWINT_1) {
253 /* If so, check system call restarting.. */
254 switch (regs->regs[0]) {
255 case -ERESTART_RESTARTBLOCK:
256 case -ERESTARTNOHAND:
257 regs->regs[0] = -EINTR;
258 break;
259
260 case -ERESTARTSYS:
261 if (!(ka->sa.sa_flags & SA_RESTART)) {
262 regs->regs[0] = -EINTR;
263 break;
264 }
265 /* fallthrough */
266 case -ERESTARTNOINTR:
267 /* Reload caller-saves to restore r0..r5 and r10. */
268 regs->flags |= PT_FLAGS_CALLER_SAVES;
269 regs->regs[0] = regs->orig_r0;
270 regs->pc -= 8;
271 }
272 }
273
274 /* Set up the stack frame */
275 #ifdef CONFIG_COMPAT
276 if (is_compat_task())
277 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
278 else
279 #endif
280 ret = setup_rt_frame(sig, ka, info, oldset, regs);
281 if (ret == 0) {
282 /* This code is only called from system calls or from
283 * the work_pending path in the return-to-user code, and
284 * either way we can re-enable interrupts unconditionally.
285 */
286 block_sigmask(ka, sig);
287 }
288
289 return ret;
290 }
291
292 /*
293 * Note that 'init' is a special process: it doesn't get signals it doesn't
294 * want to handle. Thus you cannot kill init even with a SIGKILL even by
295 * mistake.
296 */
do_signal(struct pt_regs * regs)297 void do_signal(struct pt_regs *regs)
298 {
299 siginfo_t info;
300 int signr;
301 struct k_sigaction ka;
302 sigset_t *oldset;
303
304 /*
305 * i386 will check if we're coming from kernel mode and bail out
306 * here. In my experience this just turns weird crashes into
307 * weird spin-hangs. But if we find a case where this seems
308 * helpful, we can reinstate the check on "!user_mode(regs)".
309 */
310
311 if (current_thread_info()->status & TS_RESTORE_SIGMASK)
312 oldset = ¤t->saved_sigmask;
313 else
314 oldset = ¤t->blocked;
315
316 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
317 if (signr > 0) {
318 /* Whee! Actually deliver the signal. */
319 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
320 /*
321 * A signal was successfully delivered; the saved
322 * sigmask will have been stored in the signal frame,
323 * and will be restored by sigreturn, so we can simply
324 * clear the TS_RESTORE_SIGMASK flag.
325 */
326 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
327 }
328
329 goto done;
330 }
331
332 /* Did we come from a system call? */
333 if (regs->faultnum == INT_SWINT_1) {
334 /* Restart the system call - no handlers present */
335 switch (regs->regs[0]) {
336 case -ERESTARTNOHAND:
337 case -ERESTARTSYS:
338 case -ERESTARTNOINTR:
339 regs->flags |= PT_FLAGS_CALLER_SAVES;
340 regs->regs[0] = regs->orig_r0;
341 regs->pc -= 8;
342 break;
343
344 case -ERESTART_RESTARTBLOCK:
345 regs->flags |= PT_FLAGS_CALLER_SAVES;
346 regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
347 regs->pc -= 8;
348 break;
349 }
350 }
351
352 /* If there's no signal to deliver, just put the saved sigmask back. */
353 if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
354 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
355 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
356 }
357
358 done:
359 /* Avoid double syscall restart if there are nested signals. */
360 regs->faultnum = INT_SWINT_1_SIGRETURN;
361 }
362
363 int show_unhandled_signals = 1;
364
crashinfo(char * str)365 static int __init crashinfo(char *str)
366 {
367 unsigned long val;
368 const char *word;
369
370 if (*str == '\0')
371 val = 2;
372 else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
373 return 0;
374 show_unhandled_signals = val;
375 switch (show_unhandled_signals) {
376 case 0:
377 word = "No";
378 break;
379 case 1:
380 word = "One-line";
381 break;
382 default:
383 word = "Detailed";
384 break;
385 }
386 pr_info("%s crash reports will be generated on the console\n", word);
387 return 1;
388 }
389 __setup("crashinfo", crashinfo);
390
dump_mem(void __user * address)391 static void dump_mem(void __user *address)
392 {
393 void __user *addr;
394 enum { region_size = 256, bytes_per_line = 16 };
395 int i, j, k;
396 int found_readable_mem = 0;
397
398 pr_err("\n");
399 if (!access_ok(VERIFY_READ, address, 1)) {
400 pr_err("Not dumping at address 0x%lx (kernel address)\n",
401 (unsigned long)address);
402 return;
403 }
404
405 addr = (void __user *)
406 (((unsigned long)address & -bytes_per_line) - region_size/2);
407 if (addr > address)
408 addr = NULL;
409 for (i = 0; i < region_size;
410 addr += bytes_per_line, i += bytes_per_line) {
411 unsigned char buf[bytes_per_line];
412 char line[100];
413 if (copy_from_user(buf, addr, bytes_per_line))
414 continue;
415 if (!found_readable_mem) {
416 pr_err("Dumping memory around address 0x%lx:\n",
417 (unsigned long)address);
418 found_readable_mem = 1;
419 }
420 j = sprintf(line, REGFMT":", (unsigned long)addr);
421 for (k = 0; k < bytes_per_line; ++k)
422 j += sprintf(&line[j], " %02x", buf[k]);
423 pr_err("%s\n", line);
424 }
425 if (!found_readable_mem)
426 pr_err("No readable memory around address 0x%lx\n",
427 (unsigned long)address);
428 }
429
trace_unhandled_signal(const char * type,struct pt_regs * regs,unsigned long address,int sig)430 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
431 unsigned long address, int sig)
432 {
433 struct task_struct *tsk = current;
434
435 if (show_unhandled_signals == 0)
436 return;
437
438 /* If the signal is handled, don't show it here. */
439 if (!is_global_init(tsk)) {
440 void __user *handler =
441 tsk->sighand->action[sig-1].sa.sa_handler;
442 if (handler != SIG_IGN && handler != SIG_DFL)
443 return;
444 }
445
446 /* Rate-limit the one-line output, not the detailed output. */
447 if (show_unhandled_signals <= 1 && !printk_ratelimit())
448 return;
449
450 printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
451 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
452 tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
453
454 print_vma_addr(KERN_CONT " in ", regs->pc);
455
456 printk(KERN_CONT "\n");
457
458 if (show_unhandled_signals > 1) {
459 switch (sig) {
460 case SIGILL:
461 case SIGFPE:
462 case SIGSEGV:
463 case SIGBUS:
464 pr_err("User crash: signal %d,"
465 " trap %ld, address 0x%lx\n",
466 sig, regs->faultnum, address);
467 show_regs(regs);
468 dump_mem((void __user *)address);
469 break;
470 default:
471 pr_err("User crash: signal %d, trap %ld\n",
472 sig, regs->faultnum);
473 break;
474 }
475 }
476 }
477