disable some mediatekl custom warnings
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / openrisc / kernel / signal.c
1 /*
2 * OpenRISC signal.c
3 *
4 * Linux architectural port borrowing liberally from similar works of
5 * others. All original copyrights apply as per the original source
6 * declaration.
7 *
8 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17
18 #include <linux/sched.h>
19 #include <linux/mm.h>
20 #include <linux/smp.h>
21 #include <linux/kernel.h>
22 #include <linux/signal.h>
23 #include <linux/errno.h>
24 #include <linux/wait.h>
25 #include <linux/ptrace.h>
26 #include <linux/unistd.h>
27 #include <linux/stddef.h>
28 #include <linux/tracehook.h>
29
30 #include <asm/processor.h>
31 #include <asm/ucontext.h>
32 #include <asm/uaccess.h>
33
34 #define DEBUG_SIG 0
35
36 struct rt_sigframe {
37 struct siginfo *pinfo;
38 void *puc;
39 struct siginfo info;
40 struct ucontext uc;
41 unsigned char retcode[16]; /* trampoline code */
42 };
43
44 static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
45 {
46 unsigned int err = 0;
47
48 /* Alwys make any pending restarted system call return -EINTR */
49 current_thread_info()->restart_block.fn = do_no_restart_syscall;
50
51 /*
52 * Restore the regs from &sc->regs.
53 * (sc is already checked for VERIFY_READ since the sigframe was
54 * checked in sys_sigreturn previously)
55 */
56 if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)))
57 goto badframe;
58 if (__copy_from_user(&regs->pc, &sc->regs.pc, sizeof(unsigned long)))
59 goto badframe;
60 if (__copy_from_user(&regs->sr, &sc->regs.sr, sizeof(unsigned long)))
61 goto badframe;
62
63 /* make sure the SM-bit is cleared so user-mode cannot fool us */
64 regs->sr &= ~SPR_SR_SM;
65
66 /* TODO: the other ports use regs->orig_XX to disable syscall checks
67 * after this completes, but we don't use that mechanism. maybe we can
68 * use it now ?
69 */
70
71 return err;
72
73 badframe:
74 return 1;
75 }
76
77 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
78 {
79 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
80 sigset_t set;
81
82 /*
83 * Since we stacked the signal on a dword boundary,
84 * then frame should be dword aligned here. If it's
85 * not, then the user is trying to mess with us.
86 */
87 if (((long)frame) & 3)
88 goto badframe;
89
90 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
91 goto badframe;
92 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
93 goto badframe;
94
95 set_current_blocked(&set);
96
97 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
98 goto badframe;
99
100 if (restore_altstack(&frame->uc.uc_stack))
101 goto badframe;
102
103 return regs->gpr[11];
104
105 badframe:
106 force_sig(SIGSEGV, current);
107 return 0;
108 }
109
110 /*
111 * Set up a signal frame.
112 */
113
114 static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
115 unsigned long mask)
116 {
117 int err = 0;
118
119 /* copy the regs */
120
121 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
122 err |= __copy_to_user(&sc->regs.pc, &regs->pc, sizeof(unsigned long));
123 err |= __copy_to_user(&sc->regs.sr, &regs->sr, sizeof(unsigned long));
124
125 /* then some other stuff */
126
127 err |= __put_user(mask, &sc->oldmask);
128
129 return err;
130 }
131
132 static inline unsigned long align_sigframe(unsigned long sp)
133 {
134 return sp & ~3UL;
135 }
136
137 /*
138 * Work out where the signal frame should go. It's either on the user stack
139 * or the alternate stack.
140 */
141
142 static inline void __user *get_sigframe(struct k_sigaction *ka,
143 struct pt_regs *regs, size_t frame_size)
144 {
145 unsigned long sp = regs->sp;
146 int onsigstack = on_sig_stack(sp);
147
148 /* redzone */
149 sp -= STACK_FRAME_OVERHEAD;
150
151 /* This is the X/Open sanctioned signal stack switching. */
152 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) {
153 if (current->sas_ss_size)
154 sp = current->sas_ss_sp + current->sas_ss_size;
155 }
156
157 sp = align_sigframe(sp - frame_size);
158
159 /*
160 * If we are on the alternate signal stack and would overflow it, don't.
161 * Return an always-bogus address instead so we will die with SIGSEGV.
162 */
163 if (onsigstack && !likely(on_sig_stack(sp)))
164 return (void __user *)-1L;
165
166 return (void __user *)sp;
167 }
168
169 /* grab and setup a signal frame.
170 *
171 * basically we stack a lot of state info, and arrange for the
172 * user-mode program to return to the kernel using either a
173 * trampoline which performs the syscall sigreturn, or a provided
174 * user-mode trampoline.
175 */
176 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
177 sigset_t *set, struct pt_regs *regs)
178 {
179 struct rt_sigframe *frame;
180 unsigned long return_ip;
181 int err = 0;
182
183 frame = get_sigframe(ka, regs, sizeof(*frame));
184
185 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
186 goto give_sigsegv;
187
188 err |= __put_user(&frame->info, &frame->pinfo);
189 err |= __put_user(&frame->uc, &frame->puc);
190
191 if (ka->sa.sa_flags & SA_SIGINFO)
192 err |= copy_siginfo_to_user(&frame->info, info);
193 if (err)
194 goto give_sigsegv;
195
196 /* Clear all the bits of the ucontext we don't use. */
197 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
198 err |= __put_user(0, &frame->uc.uc_flags);
199 err |= __put_user(NULL, &frame->uc.uc_link);
200 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
201 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
202
203 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
204
205 if (err)
206 goto give_sigsegv;
207
208 /* trampoline - the desired return ip is the retcode itself */
209 return_ip = (unsigned long)&frame->retcode;
210 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
211 err |= __put_user(0xa960, (short *)(frame->retcode + 0));
212 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
213 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
214 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
215
216 if (err)
217 goto give_sigsegv;
218
219 /* TODO what is the current->exec_domain stuff and invmap ? */
220
221 /* Set up registers for signal handler */
222 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */
223 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
224 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */
225 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
226 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
227
228 /* actually move the usp to reflect the stacked frame */
229 regs->sp = (unsigned long)frame;
230
231 return 0;
232
233 give_sigsegv:
234 force_sigsegv(sig, current);
235 return -EFAULT;
236 }
237
238 static inline void
239 handle_signal(unsigned long sig,
240 siginfo_t *info, struct k_sigaction *ka,
241 struct pt_regs *regs)
242 {
243 int ret;
244
245 ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
246 if (ret)
247 return;
248
249 signal_delivered(sig, info, ka, regs,
250 test_thread_flag(TIF_SINGLESTEP));
251 }
252
253 /*
254 * Note that 'init' is a special process: it doesn't get signals it doesn't
255 * want to handle. Thus you cannot kill init even with a SIGKILL even by
256 * mistake.
257 *
258 * Also note that the regs structure given here as an argument, is the latest
259 * pushed pt_regs. It may or may not be the same as the first pushed registers
260 * when the initial usermode->kernelmode transition took place. Therefore
261 * we can use user_mode(regs) to see if we came directly from kernel or user
262 * mode below.
263 */
264
265 void do_signal(struct pt_regs *regs)
266 {
267 siginfo_t info;
268 int signr;
269 struct k_sigaction ka;
270
271 /*
272 * We want the common case to go fast, which
273 * is why we may in certain cases get here from
274 * kernel mode. Just return without doing anything
275 * if so.
276 */
277 if (!user_mode(regs))
278 return;
279
280 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
281
282 /* If we are coming out of a syscall then we need
283 * to check if the syscall was interrupted and wants to be
284 * restarted after handling the signal. If so, the original
285 * syscall number is put back into r11 and the PC rewound to
286 * point at the l.sys instruction that resulted in the
287 * original syscall. Syscall results other than the four
288 * below mean that the syscall executed to completion and no
289 * restart is necessary.
290 */
291 if (regs->orig_gpr11) {
292 int restart = 0;
293
294 switch (regs->gpr[11]) {
295 case -ERESTART_RESTARTBLOCK:
296 case -ERESTARTNOHAND:
297 /* Restart if there is no signal handler */
298 restart = (signr <= 0);
299 break;
300 case -ERESTARTSYS:
301 /* Restart if there no signal handler or
302 * SA_RESTART flag is set */
303 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
304 break;
305 case -ERESTARTNOINTR:
306 /* Always restart */
307 restart = 1;
308 break;
309 }
310
311 if (restart) {
312 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
313 regs->gpr[11] = __NR_restart_syscall;
314 else
315 regs->gpr[11] = regs->orig_gpr11;
316 regs->pc -= 4;
317 } else {
318 regs->gpr[11] = -EINTR;
319 }
320 }
321
322 if (signr <= 0) {
323 /* no signal to deliver so we just put the saved sigmask
324 * back */
325 restore_saved_sigmask();
326 } else { /* signr > 0 */
327 /* Whee! Actually deliver the signal. */
328 handle_signal(signr, &info, &ka, regs);
329 }
330
331 return;
332 }
333
334 asmlinkage void do_notify_resume(struct pt_regs *regs)
335 {
336 if (current_thread_info()->flags & _TIF_SIGPENDING)
337 do_signal(regs);
338
339 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
340 clear_thread_flag(TIF_NOTIFY_RESUME);
341 tracehook_notify_resume(regs);
342 }
343 }