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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 <asm/vdso.h>
37#include <arch/interrupts.h>
38
39#define DEBUG_SIG 0
40
41/*
42 * Do a signal return; undo the signal stack.
43 */
44
45int restore_sigcontext(struct pt_regs *regs,
46 struct sigcontext __user *sc)
47{
48 int err = 0;
49 int i;
50
51 /* Always make any pending restarted system calls return -EINTR */
52 current_thread_info()->restart_block.fn = do_no_restart_syscall;
53
54 /*
55 * Enforce that sigcontext is like pt_regs, and doesn't mess
56 * up our stack alignment rules.
57 */
58 BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
59 BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
60
61 for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
62 err |= __get_user(regs->regs[i], &sc->gregs[i]);
63
64 /* Ensure that the PL is always set to USER_PL. */
65 regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
66
67 regs->faultnum = INT_SWINT_1_SIGRETURN;
68
69 return err;
70}
71
72void signal_fault(const char *type, struct pt_regs *regs,
73 void __user *frame, int sig)
74{
75 trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
76 force_sigsegv(sig, current);
77}
78
79/* The assembly shim for this function arranges to ignore the return value. */
80SYSCALL_DEFINE0(rt_sigreturn)
81{
82 struct pt_regs *regs = current_pt_regs();
83 struct rt_sigframe __user *frame =
84 (struct rt_sigframe __user *)(regs->sp);
85 sigset_t set;
86
87 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
88 goto badframe;
89 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
90 goto badframe;
91
92 set_current_blocked(&set);
93
94 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
95 goto badframe;
96
97 if (restore_altstack(&frame->uc.uc_stack))
98 goto badframe;
99
100 return 0;
101
102badframe:
103 signal_fault("bad sigreturn frame", regs, frame, 0);
104 return 0;
105}
106
107/*
108 * Set up a signal frame.
109 */
110
111int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
112{
113 int i, err = 0;
114
115 for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
116 err |= __put_user(regs->regs[i], &sc->gregs[i]);
117
118 return err;
119}
120
121/*
122 * Determine which stack to use..
123 */
124static inline void __user *get_sigframe(struct k_sigaction *ka,
125 struct pt_regs *regs,
126 size_t frame_size)
127{
128 unsigned long sp;
129
130 /* Default to using normal stack */
131 sp = regs->sp;
132
133 /*
134 * If we are on the alternate signal stack and would overflow
135 * it, don't. Return an always-bogus address instead so we
136 * will die with SIGSEGV.
137 */
138 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
139 return (void __user __force *)-1UL;
140
141 /* This is the X/Open sanctioned signal stack switching. */
142 if (ka->sa.sa_flags & SA_ONSTACK) {
143 if (sas_ss_flags(sp) == 0)
144 sp = current->sas_ss_sp + current->sas_ss_size;
145 }
146
147 sp -= frame_size;
148 /*
149 * Align the stack pointer according to the TILE ABI,
150 * i.e. so that on function entry (sp & 15) == 0.
151 */
152 sp &= -16UL;
153 return (void __user *) sp;
154}
155
156static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
157 sigset_t *set, struct pt_regs *regs)
158{
159 unsigned long restorer;
160 struct rt_sigframe __user *frame;
161 int err = 0;
162 int usig;
163
164 frame = get_sigframe(ka, regs, sizeof(*frame));
165
166 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
167 goto give_sigsegv;
168
169 usig = current_thread_info()->exec_domain
170 && current_thread_info()->exec_domain->signal_invmap
171 && sig < 32
172 ? current_thread_info()->exec_domain->signal_invmap[sig]
173 : sig;
174
175 /* Always write at least the signal number for the stack backtracer. */
176 if (ka->sa.sa_flags & SA_SIGINFO) {
177 /* At sigreturn time, restore the callee-save registers too. */
178 err |= copy_siginfo_to_user(&frame->info, info);
179 regs->flags |= PT_FLAGS_RESTORE_REGS;
180 } else {
181 err |= __put_user(info->si_signo, &frame->info.si_signo);
182 }
183
184 /* Create the ucontext. */
185 err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
186 err |= __put_user(0, &frame->uc.uc_flags);
187 err |= __put_user(NULL, &frame->uc.uc_link);
188 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
189 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
190 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
191 if (err)
192 goto give_sigsegv;
193
194 restorer = VDSO_SYM(&__vdso_rt_sigreturn);
195 if (ka->sa.sa_flags & SA_RESTORER)
196 restorer = (unsigned long) ka->sa.sa_restorer;
197
198 /*
199 * Set up registers for signal handler.
200 * Registers that we don't modify keep the value they had from
201 * user-space at the time we took the signal.
202 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
203 * since some things rely on this (e.g. glibc's debug/segfault.c).
204 */
205 regs->pc = (unsigned long) ka->sa.sa_handler;
206 regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
207 regs->sp = (unsigned long) frame;
208 regs->lr = restorer;
209 regs->regs[0] = (unsigned long) usig;
210 regs->regs[1] = (unsigned long) &frame->info;
211 regs->regs[2] = (unsigned long) &frame->uc;
212 regs->flags |= PT_FLAGS_CALLER_SAVES;
213 return 0;
214
215give_sigsegv:
216 signal_fault("bad setup frame", regs, frame, sig);
217 return -EFAULT;
218}
219
220/*
221 * OK, we're invoking a handler
222 */
223
224static void handle_signal(unsigned long sig, siginfo_t *info,
225 struct k_sigaction *ka,
226 struct pt_regs *regs)
227{
228 sigset_t *oldset = sigmask_to_save();
229 int ret;
230
231 /* Are we from a system call? */
232 if (regs->faultnum == INT_SWINT_1) {
233 /* If so, check system call restarting.. */
234 switch (regs->regs[0]) {
235 case -ERESTART_RESTARTBLOCK:
236 case -ERESTARTNOHAND:
237 regs->regs[0] = -EINTR;
238 break;
239
240 case -ERESTARTSYS:
241 if (!(ka->sa.sa_flags & SA_RESTART)) {
242 regs->regs[0] = -EINTR;
243 break;
244 }
245 /* fallthrough */
246 case -ERESTARTNOINTR:
247 /* Reload caller-saves to restore r0..r5 and r10. */
248 regs->flags |= PT_FLAGS_CALLER_SAVES;
249 regs->regs[0] = regs->orig_r0;
250 regs->pc -= 8;
251 }
252 }
253
254 /* Set up the stack frame */
255#ifdef CONFIG_COMPAT
256 if (is_compat_task())
257 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
258 else
259#endif
260 ret = setup_rt_frame(sig, ka, info, oldset, regs);
261 if (ret)
262 return;
263 signal_delivered(sig, info, ka, regs,
264 test_thread_flag(TIF_SINGLESTEP));
265}
266
267/*
268 * Note that 'init' is a special process: it doesn't get signals it doesn't
269 * want to handle. Thus you cannot kill init even with a SIGKILL even by
270 * mistake.
271 */
272void do_signal(struct pt_regs *regs)
273{
274 siginfo_t info;
275 int signr;
276 struct k_sigaction ka;
277
278 /*
279 * i386 will check if we're coming from kernel mode and bail out
280 * here. In my experience this just turns weird crashes into
281 * weird spin-hangs. But if we find a case where this seems
282 * helpful, we can reinstate the check on "!user_mode(regs)".
283 */
284
285 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
286 if (signr > 0) {
287 /* Whee! Actually deliver the signal. */
288 handle_signal(signr, &info, &ka, regs);
289 goto done;
290 }
291
292 /* Did we come from a system call? */
293 if (regs->faultnum == INT_SWINT_1) {
294 /* Restart the system call - no handlers present */
295 switch (regs->regs[0]) {
296 case -ERESTARTNOHAND:
297 case -ERESTARTSYS:
298 case -ERESTARTNOINTR:
299 regs->flags |= PT_FLAGS_CALLER_SAVES;
300 regs->regs[0] = regs->orig_r0;
301 regs->pc -= 8;
302 break;
303
304 case -ERESTART_RESTARTBLOCK:
305 regs->flags |= PT_FLAGS_CALLER_SAVES;
306 regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
307 regs->pc -= 8;
308 break;
309 }
310 }
311
312 /* If there's no signal to deliver, just put the saved sigmask back. */
313 restore_saved_sigmask();
314
315done:
316 /* Avoid double syscall restart if there are nested signals. */
317 regs->faultnum = INT_SWINT_1_SIGRETURN;
318}
319
320int show_unhandled_signals = 1;
321
322static int __init crashinfo(char *str)
323{
324 unsigned long val;
325 const char *word;
326
327 if (*str == '\0')
328 val = 2;
329 else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
330 return 0;
331 show_unhandled_signals = val;
332 switch (show_unhandled_signals) {
333 case 0:
334 word = "No";
335 break;
336 case 1:
337 word = "One-line";
338 break;
339 default:
340 word = "Detailed";
341 break;
342 }
343 pr_info("%s crash reports will be generated on the console\n", word);
344 return 1;
345}
346__setup("crashinfo", crashinfo);
347
348static void dump_mem(void __user *address)
349{
350 void __user *addr;
351 enum { region_size = 256, bytes_per_line = 16 };
352 int i, j, k;
353 int found_readable_mem = 0;
354
355 pr_err("\n");
356 if (!access_ok(VERIFY_READ, address, 1)) {
357 pr_err("Not dumping at address 0x%lx (kernel address)\n",
358 (unsigned long)address);
359 return;
360 }
361
362 addr = (void __user *)
363 (((unsigned long)address & -bytes_per_line) - region_size/2);
364 if (addr > address)
365 addr = NULL;
366 for (i = 0; i < region_size;
367 addr += bytes_per_line, i += bytes_per_line) {
368 unsigned char buf[bytes_per_line];
369 char line[100];
370 if (copy_from_user(buf, addr, bytes_per_line))
371 continue;
372 if (!found_readable_mem) {
373 pr_err("Dumping memory around address 0x%lx:\n",
374 (unsigned long)address);
375 found_readable_mem = 1;
376 }
377 j = sprintf(line, REGFMT":", (unsigned long)addr);
378 for (k = 0; k < bytes_per_line; ++k)
379 j += sprintf(&line[j], " %02x", buf[k]);
380 pr_err("%s\n", line);
381 }
382 if (!found_readable_mem)
383 pr_err("No readable memory around address 0x%lx\n",
384 (unsigned long)address);
385}
386
387void trace_unhandled_signal(const char *type, struct pt_regs *regs,
388 unsigned long address, int sig)
389{
390 struct task_struct *tsk = current;
391
392 if (show_unhandled_signals == 0)
393 return;
394
395 /* If the signal is handled, don't show it here. */
396 if (!is_global_init(tsk)) {
397 void __user *handler =
398 tsk->sighand->action[sig-1].sa.sa_handler;
399 if (handler != SIG_IGN && handler != SIG_DFL)
400 return;
401 }
402
403 /* Rate-limit the one-line output, not the detailed output. */
404 if (show_unhandled_signals <= 1 && !printk_ratelimit())
405 return;
406
407 printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
408 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
409 tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
410
411 print_vma_addr(KERN_CONT " in ", regs->pc);
412
413 printk(KERN_CONT "\n");
414
415 if (show_unhandled_signals > 1) {
416 switch (sig) {
417 case SIGILL:
418 case SIGFPE:
419 case SIGSEGV:
420 case SIGBUS:
421 pr_err("User crash: signal %d,"
422 " trap %ld, address 0x%lx\n",
423 sig, regs->faultnum, address);
424 show_regs(regs);
425 dump_mem((void __user *)address);
426 break;
427 default:
428 pr_err("User crash: signal %d, trap %ld\n",
429 sig, regs->faultnum);
430 break;
431 }
432 }
433}