1 /*
2 * Copyright 2004-2010 Analog Devices Inc.
3 *
4 * Licensed under the GPL-2 or later
5 */
6
7 #include <linux/signal.h>
8 #include <linux/syscalls.h>
9 #include <linux/ptrace.h>
10 #include <linux/tty.h>
11 #include <linux/personality.h>
12 #include <linux/binfmts.h>
13 #include <linux/freezer.h>
14 #include <linux/uaccess.h>
15 #include <linux/tracehook.h>
16
17 #include <asm/cacheflush.h>
18 #include <asm/ucontext.h>
19 #include <asm/fixed_code.h>
20 #include <asm/syscall.h>
21
22 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
23
24 /* Location of the trace bit in SYSCFG. */
25 #define TRACE_BITS 0x0001
26
27 struct fdpic_func_descriptor {
28 unsigned long text;
29 unsigned long GOT;
30 };
31
32 struct rt_sigframe {
33 int sig;
34 struct siginfo *pinfo;
35 void *puc;
36 /* This is no longer needed by the kernel, but unfortunately userspace
37 * code expects it to be there. */
38 char retcode[8];
39 struct siginfo info;
40 struct ucontext uc;
41 };
42
sys_sigaltstack(const stack_t __user * uss,stack_t __user * uoss)43 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
44 {
45 return do_sigaltstack(uss, uoss, rdusp());
46 }
47
48 static inline int
rt_restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc,int * pr0)49 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
50 {
51 unsigned long usp = 0;
52 int err = 0;
53
54 /* Always make any pending restarted system calls return -EINTR */
55 current_thread_info()->restart_block.fn = do_no_restart_syscall;
56
57 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
58
59 /* restore passed registers */
60 RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
61 RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
62 RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
63 RESTORE(p4); RESTORE(p5);
64 err |= __get_user(usp, &sc->sc_usp);
65 wrusp(usp);
66 RESTORE(a0w); RESTORE(a1w);
67 RESTORE(a0x); RESTORE(a1x);
68 RESTORE(astat);
69 RESTORE(rets);
70 RESTORE(pc);
71 RESTORE(retx);
72 RESTORE(fp);
73 RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
74 RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
75 RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
76 RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
77 RESTORE(lc0); RESTORE(lc1);
78 RESTORE(lt0); RESTORE(lt1);
79 RESTORE(lb0); RESTORE(lb1);
80 RESTORE(seqstat);
81
82 regs->orig_p0 = -1; /* disable syscall checks */
83
84 *pr0 = regs->r0;
85 return err;
86 }
87
do_rt_sigreturn(unsigned long __unused)88 asmlinkage int do_rt_sigreturn(unsigned long __unused)
89 {
90 struct pt_regs *regs = (struct pt_regs *)__unused;
91 unsigned long usp = rdusp();
92 struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
93 sigset_t set;
94 int r0;
95
96 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
97 goto badframe;
98 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
99 goto badframe;
100
101 sigdelsetmask(&set, ~_BLOCKABLE);
102 spin_lock_irq(¤t->sighand->siglock);
103 current->blocked = set;
104 recalc_sigpending();
105 spin_unlock_irq(¤t->sighand->siglock);
106
107 if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
108 goto badframe;
109
110 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
111 goto badframe;
112
113 return r0;
114
115 badframe:
116 force_sig(SIGSEGV, current);
117 return 0;
118 }
119
rt_setup_sigcontext(struct sigcontext * sc,struct pt_regs * regs)120 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
121 {
122 int err = 0;
123
124 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
125
126 SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
127 SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
128 SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
129 SETUP(p4); SETUP(p5);
130 err |= __put_user(rdusp(), &sc->sc_usp);
131 SETUP(a0w); SETUP(a1w);
132 SETUP(a0x); SETUP(a1x);
133 SETUP(astat);
134 SETUP(rets);
135 SETUP(pc);
136 SETUP(retx);
137 SETUP(fp);
138 SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
139 SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
140 SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
141 SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
142 SETUP(lc0); SETUP(lc1);
143 SETUP(lt0); SETUP(lt1);
144 SETUP(lb0); SETUP(lb1);
145 SETUP(seqstat);
146
147 return err;
148 }
149
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size)150 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
151 size_t frame_size)
152 {
153 unsigned long usp;
154
155 /* Default to using normal stack. */
156 usp = rdusp();
157
158 /* This is the X/Open sanctioned signal stack switching. */
159 if (ka->sa.sa_flags & SA_ONSTACK) {
160 if (!on_sig_stack(usp))
161 usp = current->sas_ss_sp + current->sas_ss_size;
162 }
163 return (void *)((usp - frame_size) & -8UL);
164 }
165
166 static int
setup_rt_frame(int sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)167 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
168 sigset_t * set, struct pt_regs *regs)
169 {
170 struct rt_sigframe *frame;
171 int err = 0;
172
173 frame = get_sigframe(ka, regs, sizeof(*frame));
174
175 err |= __put_user((current_thread_info()->exec_domain
176 && current_thread_info()->exec_domain->signal_invmap
177 && sig < 32
178 ? current_thread_info()->exec_domain->
179 signal_invmap[sig] : sig), &frame->sig);
180
181 err |= __put_user(&frame->info, &frame->pinfo);
182 err |= __put_user(&frame->uc, &frame->puc);
183 err |= copy_siginfo_to_user(&frame->info, info);
184
185 /* Create the ucontext. */
186 err |= __put_user(0, &frame->uc.uc_flags);
187 err |= __put_user(0, &frame->uc.uc_link);
188 err |=
189 __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
190 err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
191 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
192 err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
193 err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
194
195 if (err)
196 goto give_sigsegv;
197
198 /* Set up registers for signal handler */
199 wrusp((unsigned long)frame);
200 if (current->personality & FDPIC_FUNCPTRS) {
201 struct fdpic_func_descriptor __user *funcptr =
202 (struct fdpic_func_descriptor *) ka->sa.sa_handler;
203 __get_user(regs->pc, &funcptr->text);
204 __get_user(regs->p3, &funcptr->GOT);
205 } else
206 regs->pc = (unsigned long)ka->sa.sa_handler;
207 regs->rets = SIGRETURN_STUB;
208
209 regs->r0 = frame->sig;
210 regs->r1 = (unsigned long)(&frame->info);
211 regs->r2 = (unsigned long)(&frame->uc);
212
213 return 0;
214
215 give_sigsegv:
216 if (sig == SIGSEGV)
217 ka->sa.sa_handler = SIG_DFL;
218 force_sig(SIGSEGV, current);
219 return -EFAULT;
220 }
221
222 static inline void
handle_restart(struct pt_regs * regs,struct k_sigaction * ka,int has_handler)223 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
224 {
225 switch (regs->r0) {
226 case -ERESTARTNOHAND:
227 if (!has_handler)
228 goto do_restart;
229 regs->r0 = -EINTR;
230 break;
231
232 case -ERESTARTSYS:
233 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
234 regs->r0 = -EINTR;
235 break;
236 }
237 /* fallthrough */
238 case -ERESTARTNOINTR:
239 do_restart:
240 regs->p0 = regs->orig_p0;
241 regs->r0 = regs->orig_r0;
242 regs->pc -= 2;
243 break;
244
245 case -ERESTART_RESTARTBLOCK:
246 regs->p0 = __NR_restart_syscall;
247 regs->pc -= 2;
248 break;
249 }
250 }
251
252 /*
253 * OK, we're invoking a handler
254 */
255 static int
handle_signal(int sig,siginfo_t * info,struct k_sigaction * ka,sigset_t * oldset,struct pt_regs * regs)256 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
257 sigset_t *oldset, struct pt_regs *regs)
258 {
259 int ret;
260
261 /* are we from a system call? to see pt_regs->orig_p0 */
262 if (regs->orig_p0 >= 0)
263 /* If so, check system call restarting.. */
264 handle_restart(regs, ka, 1);
265
266 /* set up the stack frame */
267 ret = setup_rt_frame(sig, ka, info, oldset, regs);
268
269 if (ret == 0) {
270 spin_lock_irq(¤t->sighand->siglock);
271 sigorsets(¤t->blocked, ¤t->blocked,
272 &ka->sa.sa_mask);
273 if (!(ka->sa.sa_flags & SA_NODEFER))
274 sigaddset(¤t->blocked, sig);
275 recalc_sigpending();
276 spin_unlock_irq(¤t->sighand->siglock);
277 }
278 return ret;
279 }
280
281 /*
282 * Note that 'init' is a special process: it doesn't get signals it doesn't
283 * want to handle. Thus you cannot kill init even with a SIGKILL even by
284 * mistake.
285 *
286 * Note that we go through the signals twice: once to check the signals
287 * that the kernel can handle, and then we build all the user-level signal
288 * handling stack-frames in one go after that.
289 */
do_signal(struct pt_regs * regs)290 asmlinkage void do_signal(struct pt_regs *regs)
291 {
292 siginfo_t info;
293 int signr;
294 struct k_sigaction ka;
295 sigset_t *oldset;
296
297 current->thread.esp0 = (unsigned long)regs;
298
299 if (try_to_freeze())
300 goto no_signal;
301
302 if (test_thread_flag(TIF_RESTORE_SIGMASK))
303 oldset = ¤t->saved_sigmask;
304 else
305 oldset = ¤t->blocked;
306
307 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
308 if (signr > 0) {
309 /* Whee! Actually deliver the signal. */
310 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
311 /* a signal was successfully delivered; the saved
312 * sigmask will have been stored in the signal frame,
313 * and will be restored by sigreturn, so we can simply
314 * clear the TIF_RESTORE_SIGMASK flag */
315 if (test_thread_flag(TIF_RESTORE_SIGMASK))
316 clear_thread_flag(TIF_RESTORE_SIGMASK);
317
318 tracehook_signal_handler(signr, &info, &ka, regs,
319 test_thread_flag(TIF_SINGLESTEP));
320 }
321
322 return;
323 }
324
325 no_signal:
326 /* Did we come from a system call? */
327 if (regs->orig_p0 >= 0)
328 /* Restart the system call - no handlers present */
329 handle_restart(regs, NULL, 0);
330
331 /* if there's no signal to deliver, we just put the saved sigmask
332 * back */
333 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
334 clear_thread_flag(TIF_RESTORE_SIGMASK);
335 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
336 }
337 }
338
339 /*
340 * notification of userspace execution resumption
341 */
do_notify_resume(struct pt_regs * regs)342 asmlinkage void do_notify_resume(struct pt_regs *regs)
343 {
344 if (test_thread_flag(TIF_SIGPENDING) || test_thread_flag(TIF_RESTORE_SIGMASK))
345 do_signal(regs);
346
347 if (test_thread_flag(TIF_NOTIFY_RESUME)) {
348 clear_thread_flag(TIF_NOTIFY_RESUME);
349 tracehook_notify_resume(regs);
350 if (current->replacement_session_keyring)
351 key_replace_session_keyring();
352 }
353 }
354
355