1 /*
2 * Signal handling
3 *
4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
5 * Copyright (C) 2008-2009 PetaLogix
6 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
7 * Copyright (C) 2001 NEC Corporation
8 * Copyright (C) 2001 Miles Bader <miles@gnu.org>
9 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
10 * Copyright (C) 1991,1992 Linus Torvalds
11 *
12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
13 *
14 * This file was derived from the sh version, arch/sh/kernel/signal.c
15 *
16 * This file is subject to the terms and conditions of the GNU General
17 * Public License. See the file COPYING in the main directory of this
18 * archive for more details.
19 */
20
21 #include <linux/sched.h>
22 #include <linux/mm.h>
23 #include <linux/smp.h>
24 #include <linux/kernel.h>
25 #include <linux/signal.h>
26 #include <linux/errno.h>
27 #include <linux/wait.h>
28 #include <linux/ptrace.h>
29 #include <linux/unistd.h>
30 #include <linux/stddef.h>
31 #include <linux/personality.h>
32 #include <linux/percpu.h>
33 #include <linux/linkage.h>
34 #include <linux/resume_user_mode.h>
35 #include <asm/entry.h>
36 #include <asm/ucontext.h>
37 #include <linux/uaccess.h>
38 #include <linux/syscalls.h>
39 #include <asm/cacheflush.h>
40 #include <asm/syscalls.h>
41
42 /*
43 * Do a signal return; undo the signal stack.
44 */
45 struct sigframe {
46 struct sigcontext sc;
47 unsigned long extramask[_NSIG_WORDS-1];
48 unsigned long tramp[2]; /* signal trampoline */
49 };
50
51 struct rt_sigframe {
52 struct siginfo info;
53 struct ucontext uc;
54 unsigned long tramp[2]; /* signal trampoline */
55 };
56
57 static int restore_sigcontext(struct pt_regs *regs,
58 struct sigcontext __user *sc, int *rval_p)
59 {
60 unsigned int err = 0;
61
62 #define COPY(x) {err |= __get_user(regs->x, &sc->regs.x); }
63 COPY(r0);
64 COPY(r1);
65 COPY(r2); COPY(r3); COPY(r4); COPY(r5);
66 COPY(r6); COPY(r7); COPY(r8); COPY(r9);
67 COPY(r10); COPY(r11); COPY(r12); COPY(r13);
68 COPY(r14); COPY(r15); COPY(r16); COPY(r17);
69 COPY(r18); COPY(r19); COPY(r20); COPY(r21);
70 COPY(r22); COPY(r23); COPY(r24); COPY(r25);
71 COPY(r26); COPY(r27); COPY(r28); COPY(r29);
72 COPY(r30); COPY(r31);
73 COPY(pc); COPY(ear); COPY(esr); COPY(fsr);
74 #undef COPY
75
76 *rval_p = regs->r3;
77
78 return err;
79 }
80
81 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
82 {
83 struct rt_sigframe __user *frame =
84 (struct rt_sigframe __user *)(regs->r1);
85
86 sigset_t set;
87 int rval;
88
89 /* Always make any pending restarted system calls return -EINTR */
90 current->restart_block.fn = do_no_restart_syscall;
91
92 if (!access_ok(frame, sizeof(*frame)))
93 goto badframe;
94
95 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
96 goto badframe;
97
98 set_current_blocked(&set);
99
100 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
101 goto badframe;
102
103 if (restore_altstack(&frame->uc.uc_stack))
104 goto badframe;
105
106 return rval;
107
108 badframe:
109 force_sig(SIGSEGV);
110 return 0;
111 }
112
113 /*
114 * Set up a signal frame.
115 */
116
117 static int
118 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
119 unsigned long mask)
120 {
121 int err = 0;
122
123 #define COPY(x) {err |= __put_user(regs->x, &sc->regs.x); }
124 COPY(r0);
125 COPY(r1);
126 COPY(r2); COPY(r3); COPY(r4); COPY(r5);
127 COPY(r6); COPY(r7); COPY(r8); COPY(r9);
128 COPY(r10); COPY(r11); COPY(r12); COPY(r13);
129 COPY(r14); COPY(r15); COPY(r16); COPY(r17);
130 COPY(r18); COPY(r19); COPY(r20); COPY(r21);
131 COPY(r22); COPY(r23); COPY(r24); COPY(r25);
132 COPY(r26); COPY(r27); COPY(r28); COPY(r29);
133 COPY(r30); COPY(r31);
134 COPY(pc); COPY(ear); COPY(esr); COPY(fsr);
135 #undef COPY
136
137 err |= __put_user(mask, &sc->oldmask);
138
139 return err;
140 }
141
142 /*
143 * Determine which stack to use..
144 */
145 static inline void __user *
146 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size)
147 {
148 /* Default to using normal stack */
149 unsigned long sp = sigsp(regs->r1, ksig);
150
151 return (void __user *)((sp - frame_size) & -8UL);
152 }
153
154 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
155 struct pt_regs *regs)
156 {
157 struct rt_sigframe __user *frame;
158 int err = 0, sig = ksig->sig;
159 unsigned long address = 0;
160 pmd_t *pmdp;
161 pte_t *ptep;
162
163 frame = get_sigframe(ksig, regs, sizeof(*frame));
164
165 if (!access_ok(frame, sizeof(*frame)))
166 return -EFAULT;
167
168 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
169 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
170
171 /* Create the ucontext. */
172 err |= __put_user(0, &frame->uc.uc_flags);
173 err |= __put_user(NULL, &frame->uc.uc_link);
174 err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
175 err |= setup_sigcontext(&frame->uc.uc_mcontext,
176 regs, set->sig[0]);
177 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
178
179 /* Set up to return from userspace. If provided, use a stub
180 already in userspace. */
181 /* minus 8 is offset to cater for "rtsd r15,8" */
182 /* addi r12, r0, __NR_sigreturn */
183 err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
184 frame->tramp + 0);
185 /* brki r14, 0x8 */
186 err |= __put_user(0xb9cc0008, frame->tramp + 1);
187
188 /* Return from sighandler will jump to the tramp.
189 Negative 8 offset because return is rtsd r15, 8 */
190 regs->r15 = ((unsigned long)frame->tramp)-8;
191
192 address = ((unsigned long)frame->tramp);
193 pmdp = pmd_off(current->mm, address);
194
195 preempt_disable();
196 ptep = pte_offset_map(pmdp, address);
197 if (ptep && pte_present(*ptep)) {
198 address = (unsigned long) page_address(pte_page(*ptep));
199 /* MS: I need add offset in page */
200 address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
201 /* MS address is virtual */
202 address = __virt_to_phys(address);
203 invalidate_icache_range(address, address + 8);
204 flush_dcache_range(address, address + 8);
205 }
206 if (ptep)
207 pte_unmap(ptep);
208 preempt_enable();
209 if (err)
210 return -EFAULT;
211
212 /* Set up registers for signal handler */
213 regs->r1 = (unsigned long) frame;
214
215 /* Signal handler args: */
216 regs->r5 = sig; /* arg 0: signum */
217 regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
218 regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
219 /* Offset to handle microblaze rtid r14, 0 */
220 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
221
222 #ifdef DEBUG_SIG
223 pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
224 current->comm, current->pid, frame, regs->pc);
225 #endif
226
227 return 0;
228 }
229
230 /* Handle restarting system calls */
231 static inline void
232 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
233 {
234 switch (regs->r3) {
235 case -ERESTART_RESTARTBLOCK:
236 case -ERESTARTNOHAND:
237 if (!has_handler)
238 goto do_restart;
239 regs->r3 = -EINTR;
240 break;
241 case -ERESTARTSYS:
242 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
243 regs->r3 = -EINTR;
244 break;
245 }
246 fallthrough;
247 case -ERESTARTNOINTR:
248 do_restart:
249 /* offset of 4 bytes to re-execute trap (brki) instruction */
250 regs->pc -= 4;
251 break;
252 }
253 }
254
255 /*
256 * OK, we're invoking a handler
257 */
258
259 static void
260 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
261 {
262 sigset_t *oldset = sigmask_to_save();
263 int ret;
264
265 /* Set up the stack frame */
266 ret = setup_rt_frame(ksig, oldset, regs);
267
268 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
269 }
270
271 /*
272 * Note that 'init' is a special process: it doesn't get signals it doesn't
273 * want to handle. Thus you cannot kill init even with a SIGKILL even by
274 * mistake.
275 *
276 * Note that we go through the signals twice: once to check the signals that
277 * the kernel can handle, and then we build all the user-level signal handling
278 * stack-frames in one go after that.
279 */
280 static void do_signal(struct pt_regs *regs, int in_syscall)
281 {
282 struct ksignal ksig;
283
284 #ifdef DEBUG_SIG
285 pr_info("do signal: %p %d\n", regs, in_syscall);
286 pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
287 regs->r12, read_thread_flags());
288 #endif
289
290 if (get_signal(&ksig)) {
291 /* Whee! Actually deliver the signal. */
292 if (in_syscall)
293 handle_restart(regs, &ksig.ka, 1);
294 handle_signal(&ksig, regs);
295 return;
296 }
297
298 if (in_syscall)
299 handle_restart(regs, NULL, 0);
300
301 /*
302 * If there's no signal to deliver, we just put the saved sigmask
303 * back.
304 */
305 restore_saved_sigmask();
306 }
307
308 asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
309 {
310 if (test_thread_flag(TIF_SIGPENDING) ||
311 test_thread_flag(TIF_NOTIFY_SIGNAL))
312 do_signal(regs, in_syscall);
313
314 if (test_thread_flag(TIF_NOTIFY_RESUME))
315 resume_user_mode_work(regs);
316 }
317
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