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867e359b CM |
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> | |
867e359b CM |
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> | |
0707ad30 | 35 | #include <asm/syscalls.h> |
867e359b CM |
36 | #include <arch/interrupts.h> |
37 | ||
38 | #define DEBUG_SIG 0 | |
39 | ||
40 | #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) | |
41 | ||
d929b6ae CM |
42 | SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss, |
43 | stack_t __user *, uoss, struct pt_regs *, regs) | |
867e359b CM |
44 | { |
45 | return do_sigaltstack(uss, uoss, regs->sp); | |
46 | } | |
47 | ||
48 | ||
49 | /* | |
50 | * Do a signal return; undo the signal stack. | |
51 | */ | |
52 | ||
53 | int restore_sigcontext(struct pt_regs *regs, | |
81711cee | 54 | struct sigcontext __user *sc) |
867e359b CM |
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 | ||
74fca9da CM |
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 | ||
867e359b | 69 | for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i) |
74fca9da | 70 | err |= __get_user(regs->regs[i], &sc->gregs[i]); |
867e359b | 71 | |
1deb9c5d CM |
72 | /* Ensure that the PL is always set to USER_PL. */ |
73 | regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1)); | |
74 | ||
867e359b CM |
75 | regs->faultnum = INT_SWINT_1_SIGRETURN; |
76 | ||
867e359b CM |
77 | return err; |
78 | } | |
79 | ||
571d76ac CM |
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 | ||
81711cee | 87 | /* The assembly shim for this function arranges to ignore the return value. */ |
d929b6ae | 88 | SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs) |
867e359b CM |
89 | { |
90 | struct rt_sigframe __user *frame = | |
91 | (struct rt_sigframe __user *)(regs->sp); | |
92 | sigset_t set; | |
867e359b CM |
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); | |
ad092338 | 100 | set_current_blocked(&set); |
867e359b | 101 | |
81711cee | 102 | if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) |
867e359b CM |
103 | goto badframe; |
104 | ||
105 | if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) | |
106 | goto badframe; | |
107 | ||
81711cee | 108 | return 0; |
867e359b CM |
109 | |
110 | badframe: | |
571d76ac | 111 | signal_fault("bad sigreturn frame", regs, frame, 0); |
867e359b CM |
112 | return 0; |
113 | } | |
114 | ||
115 | /* | |
116 | * Set up a signal frame. | |
117 | */ | |
118 | ||
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) | |
74fca9da | 124 | err |= __put_user(regs->regs[i], &sc->gregs[i]); |
867e359b CM |
125 | |
126 | return err; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Determine which stack to use.. | |
131 | */ | |
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))) | |
0707ad30 | 147 | return (void __user __force *)-1UL; |
867e359b CM |
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 | ||
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); | |
0707ad30 CM |
195 | err |= __put_user(NULL, &frame->uc.uc_link); |
196 | err |= __put_user((void __user *)(current->sas_ss_sp), | |
867e359b CM |
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. | |
74fca9da CM |
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). | |
867e359b CM |
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; | |
74fca9da CM |
222 | regs->regs[1] = (unsigned long) &frame->info; |
223 | regs->regs[2] = (unsigned long) &frame->uc; | |
224 | regs->flags |= PT_FLAGS_CALLER_SAVES; | |
867e359b CM |
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: | |
571d76ac | 237 | signal_fault("bad setup frame", regs, frame, sig); |
867e359b CM |
238 | return -EFAULT; |
239 | } | |
240 | ||
241 | /* | |
242 | * OK, we're invoking a handler | |
243 | */ | |
244 | ||
245 | static int handle_signal(unsigned long sig, siginfo_t *info, | |
b7f9a11a | 246 | struct k_sigaction *ka, |
867e359b CM |
247 | struct pt_regs *regs) |
248 | { | |
b7f9a11a | 249 | sigset_t *oldset = sigmask_to_save(); |
867e359b CM |
250 | int ret; |
251 | ||
867e359b CM |
252 | /* Are we from a system call? */ |
253 | if (regs->faultnum == INT_SWINT_1) { | |
254 | /* If so, check system call restarting.. */ | |
255 | switch (regs->regs[0]) { | |
256 | case -ERESTART_RESTARTBLOCK: | |
257 | case -ERESTARTNOHAND: | |
258 | regs->regs[0] = -EINTR; | |
259 | break; | |
260 | ||
261 | case -ERESTARTSYS: | |
262 | if (!(ka->sa.sa_flags & SA_RESTART)) { | |
263 | regs->regs[0] = -EINTR; | |
264 | break; | |
265 | } | |
266 | /* fallthrough */ | |
267 | case -ERESTARTNOINTR: | |
268 | /* Reload caller-saves to restore r0..r5 and r10. */ | |
269 | regs->flags |= PT_FLAGS_CALLER_SAVES; | |
270 | regs->regs[0] = regs->orig_r0; | |
271 | regs->pc -= 8; | |
272 | } | |
273 | } | |
274 | ||
275 | /* Set up the stack frame */ | |
276 | #ifdef CONFIG_COMPAT | |
277 | if (is_compat_task()) | |
278 | ret = compat_setup_rt_frame(sig, ka, info, oldset, regs); | |
279 | else | |
280 | #endif | |
281 | ret = setup_rt_frame(sig, ka, info, oldset, regs); | |
282 | if (ret == 0) { | |
283 | /* This code is only called from system calls or from | |
284 | * the work_pending path in the return-to-user code, and | |
285 | * either way we can re-enable interrupts unconditionally. | |
286 | */ | |
ad092338 | 287 | block_sigmask(ka, sig); |
867e359b CM |
288 | } |
289 | ||
290 | return ret; | |
291 | } | |
292 | ||
293 | /* | |
294 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
295 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
296 | * mistake. | |
297 | */ | |
298 | void do_signal(struct pt_regs *regs) | |
299 | { | |
300 | siginfo_t info; | |
301 | int signr; | |
302 | struct k_sigaction ka; | |
867e359b CM |
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 | ||
867e359b CM |
311 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); |
312 | if (signr > 0) { | |
313 | /* Whee! Actually deliver the signal. */ | |
b7f9a11a | 314 | if (handle_signal(signr, &info, &ka, regs) == 0) { |
867e359b CM |
315 | /* |
316 | * A signal was successfully delivered; the saved | |
317 | * sigmask will have been stored in the signal frame, | |
318 | * and will be restored by sigreturn, so we can simply | |
319 | * clear the TS_RESTORE_SIGMASK flag. | |
320 | */ | |
321 | current_thread_info()->status &= ~TS_RESTORE_SIGMASK; | |
322 | } | |
323 | ||
34a89d26 | 324 | goto done; |
867e359b CM |
325 | } |
326 | ||
327 | /* Did we come from a system call? */ | |
328 | if (regs->faultnum == INT_SWINT_1) { | |
329 | /* Restart the system call - no handlers present */ | |
330 | switch (regs->regs[0]) { | |
331 | case -ERESTARTNOHAND: | |
332 | case -ERESTARTSYS: | |
333 | case -ERESTARTNOINTR: | |
334 | regs->flags |= PT_FLAGS_CALLER_SAVES; | |
335 | regs->regs[0] = regs->orig_r0; | |
336 | regs->pc -= 8; | |
337 | break; | |
338 | ||
339 | case -ERESTART_RESTARTBLOCK: | |
340 | regs->flags |= PT_FLAGS_CALLER_SAVES; | |
341 | regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall; | |
342 | regs->pc -= 8; | |
343 | break; | |
344 | } | |
345 | } | |
346 | ||
347 | /* If there's no signal to deliver, just put the saved sigmask back. */ | |
51a7b448 | 348 | restore_saved_sigmask(); |
34a89d26 CM |
349 | |
350 | done: | |
351 | /* Avoid double syscall restart if there are nested signals. */ | |
352 | regs->faultnum = INT_SWINT_1_SIGRETURN; | |
867e359b | 353 | } |
571d76ac CM |
354 | |
355 | int show_unhandled_signals = 1; | |
356 | ||
357 | static int __init crashinfo(char *str) | |
358 | { | |
359 | unsigned long val; | |
360 | const char *word; | |
361 | ||
362 | if (*str == '\0') | |
363 | val = 2; | |
364 | else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0) | |
365 | return 0; | |
366 | show_unhandled_signals = val; | |
367 | switch (show_unhandled_signals) { | |
368 | case 0: | |
369 | word = "No"; | |
370 | break; | |
371 | case 1: | |
372 | word = "One-line"; | |
373 | break; | |
374 | default: | |
375 | word = "Detailed"; | |
376 | break; | |
377 | } | |
378 | pr_info("%s crash reports will be generated on the console\n", word); | |
379 | return 1; | |
380 | } | |
381 | __setup("crashinfo", crashinfo); | |
382 | ||
383 | static void dump_mem(void __user *address) | |
384 | { | |
385 | void __user *addr; | |
386 | enum { region_size = 256, bytes_per_line = 16 }; | |
387 | int i, j, k; | |
388 | int found_readable_mem = 0; | |
389 | ||
390 | pr_err("\n"); | |
391 | if (!access_ok(VERIFY_READ, address, 1)) { | |
392 | pr_err("Not dumping at address 0x%lx (kernel address)\n", | |
393 | (unsigned long)address); | |
394 | return; | |
395 | } | |
396 | ||
397 | addr = (void __user *) | |
398 | (((unsigned long)address & -bytes_per_line) - region_size/2); | |
399 | if (addr > address) | |
400 | addr = NULL; | |
401 | for (i = 0; i < region_size; | |
402 | addr += bytes_per_line, i += bytes_per_line) { | |
403 | unsigned char buf[bytes_per_line]; | |
404 | char line[100]; | |
405 | if (copy_from_user(buf, addr, bytes_per_line)) | |
406 | continue; | |
407 | if (!found_readable_mem) { | |
408 | pr_err("Dumping memory around address 0x%lx:\n", | |
409 | (unsigned long)address); | |
410 | found_readable_mem = 1; | |
411 | } | |
412 | j = sprintf(line, REGFMT":", (unsigned long)addr); | |
413 | for (k = 0; k < bytes_per_line; ++k) | |
414 | j += sprintf(&line[j], " %02x", buf[k]); | |
415 | pr_err("%s\n", line); | |
416 | } | |
417 | if (!found_readable_mem) | |
418 | pr_err("No readable memory around address 0x%lx\n", | |
419 | (unsigned long)address); | |
420 | } | |
421 | ||
422 | void trace_unhandled_signal(const char *type, struct pt_regs *regs, | |
423 | unsigned long address, int sig) | |
424 | { | |
425 | struct task_struct *tsk = current; | |
426 | ||
427 | if (show_unhandled_signals == 0) | |
428 | return; | |
429 | ||
430 | /* If the signal is handled, don't show it here. */ | |
431 | if (!is_global_init(tsk)) { | |
432 | void __user *handler = | |
433 | tsk->sighand->action[sig-1].sa.sa_handler; | |
434 | if (handler != SIG_IGN && handler != SIG_DFL) | |
435 | return; | |
436 | } | |
437 | ||
438 | /* Rate-limit the one-line output, not the detailed output. */ | |
439 | if (show_unhandled_signals <= 1 && !printk_ratelimit()) | |
440 | return; | |
441 | ||
442 | printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d", | |
443 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, | |
444 | tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig); | |
445 | ||
446 | print_vma_addr(KERN_CONT " in ", regs->pc); | |
447 | ||
448 | printk(KERN_CONT "\n"); | |
449 | ||
450 | if (show_unhandled_signals > 1) { | |
451 | switch (sig) { | |
452 | case SIGILL: | |
453 | case SIGFPE: | |
454 | case SIGSEGV: | |
455 | case SIGBUS: | |
456 | pr_err("User crash: signal %d," | |
457 | " trap %ld, address 0x%lx\n", | |
458 | sig, regs->faultnum, address); | |
459 | show_regs(regs); | |
460 | dump_mem((void __user *)address); | |
461 | break; | |
462 | default: | |
463 | pr_err("User crash: signal %d, trap %ld\n", | |
464 | sig, regs->faultnum); | |
465 | break; | |
466 | } | |
467 | } | |
468 | } |