xref: /openbmc/linux/arch/microblaze/kernel/signal.c (revision e23feb16)
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 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/tracehook.h>
35 #include <asm/entry.h>
36 #include <asm/ucontext.h>
37 #include <linux/uaccess.h>
38 #include <asm/pgtable.h>
39 #include <asm/pgalloc.h>
40 #include <linux/syscalls.h>
41 #include <asm/cacheflush.h>
42 #include <asm/syscalls.h>
43 
44 /*
45  * Do a signal return; undo the signal stack.
46  */
47 struct sigframe {
48 	struct sigcontext sc;
49 	unsigned long extramask[_NSIG_WORDS-1];
50 	unsigned long tramp[2];	/* signal trampoline */
51 };
52 
53 struct rt_sigframe {
54 	struct siginfo info;
55 	struct ucontext uc;
56 	unsigned long tramp[2];	/* signal trampoline */
57 };
58 
59 static int restore_sigcontext(struct pt_regs *regs,
60 				struct sigcontext __user *sc, int *rval_p)
61 {
62 	unsigned int err = 0;
63 
64 #define COPY(x)		{err |= __get_user(regs->x, &sc->regs.x); }
65 	COPY(r0);
66 	COPY(r1);
67 	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
68 	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
69 	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
70 	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
71 	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
72 	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
73 	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
74 	COPY(r30);	COPY(r31);
75 	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
76 #undef COPY
77 
78 	*rval_p = regs->r3;
79 
80 	return err;
81 }
82 
83 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
84 {
85 	struct rt_sigframe __user *frame =
86 		(struct rt_sigframe __user *)(regs->r1);
87 
88 	sigset_t set;
89 	int rval;
90 
91 	/* Always make any pending restarted system calls return -EINTR */
92 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
93 
94 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
95 		goto badframe;
96 
97 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
98 		goto badframe;
99 
100 	set_current_blocked(&set);
101 
102 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
103 		goto badframe;
104 
105 	if (restore_altstack(&frame->uc.uc_stack))
106 		goto badframe;
107 
108 	return rval;
109 
110 badframe:
111 	force_sig(SIGSEGV, current);
112 	return 0;
113 }
114 
115 /*
116  * Set up a signal frame.
117  */
118 
119 static int
120 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
121 		unsigned long mask)
122 {
123 	int err = 0;
124 
125 #define COPY(x)		{err |= __put_user(regs->x, &sc->regs.x); }
126 	COPY(r0);
127 	COPY(r1);
128 	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
129 	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
130 	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
131 	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
132 	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
133 	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
134 	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
135 	COPY(r30);	COPY(r31);
136 	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
137 #undef COPY
138 
139 	err |= __put_user(mask, &sc->oldmask);
140 
141 	return err;
142 }
143 
144 /*
145  * Determine which stack to use..
146  */
147 static inline void __user *
148 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
149 {
150 	/* Default to using normal stack */
151 	unsigned long sp = regs->r1;
152 
153 	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
154 		sp = current->sas_ss_sp + current->sas_ss_size;
155 
156 	return (void __user *)((sp - frame_size) & -8UL);
157 }
158 
159 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
160 			sigset_t *set, struct pt_regs *regs)
161 {
162 	struct rt_sigframe __user *frame;
163 	int err = 0;
164 	int signal;
165 	unsigned long address = 0;
166 #ifdef CONFIG_MMU
167 	pmd_t *pmdp;
168 	pte_t *ptep;
169 #endif
170 
171 	frame = get_sigframe(ka, regs, sizeof(*frame));
172 
173 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
174 		goto give_sigsegv;
175 
176 	signal = current_thread_info()->exec_domain
177 		&& current_thread_info()->exec_domain->signal_invmap
178 		&& sig < 32
179 		? current_thread_info()->exec_domain->signal_invmap[sig]
180 		: sig;
181 
182 	if (info)
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(NULL, &frame->uc.uc_link);
188 	err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
189 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
190 			regs, set->sig[0]);
191 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
192 
193 	/* Set up to return from userspace. If provided, use a stub
194 	 already in userspace. */
195 	/* minus 8 is offset to cater for "rtsd r15,8" */
196 	/* addi r12, r0, __NR_sigreturn */
197 	err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
198 			frame->tramp + 0);
199 	/* brki r14, 0x8 */
200 	err |= __put_user(0xb9cc0008, frame->tramp + 1);
201 
202 	/* Return from sighandler will jump to the tramp.
203 	 Negative 8 offset because return is rtsd r15, 8 */
204 	regs->r15 = ((unsigned long)frame->tramp)-8;
205 
206 	address = ((unsigned long)frame->tramp);
207 #ifdef CONFIG_MMU
208 	pmdp = pmd_offset(pud_offset(
209 			pgd_offset(current->mm, address),
210 					address), address);
211 
212 	preempt_disable();
213 	ptep = pte_offset_map(pmdp, address);
214 	if (pte_present(*ptep)) {
215 		address = (unsigned long) page_address(pte_page(*ptep));
216 		/* MS: I need add offset in page */
217 		address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
218 		/* MS address is virtual */
219 		address = virt_to_phys(address);
220 		invalidate_icache_range(address, address + 8);
221 		flush_dcache_range(address, address + 8);
222 	}
223 	pte_unmap(ptep);
224 	preempt_enable();
225 #else
226 	flush_icache_range(address, address + 8);
227 	flush_dcache_range(address, address + 8);
228 #endif
229 	if (err)
230 		goto give_sigsegv;
231 
232 	/* Set up registers for signal handler */
233 	regs->r1 = (unsigned long) frame;
234 
235 	/* Signal handler args: */
236 	regs->r5 = signal; /* arg 0: signum */
237 	regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
238 	regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
239 	/* Offset to handle microblaze rtid r14, 0 */
240 	regs->pc = (unsigned long)ka->sa.sa_handler;
241 
242 	set_fs(USER_DS);
243 
244 #ifdef DEBUG_SIG
245 	pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
246 		current->comm, current->pid, frame, regs->pc);
247 #endif
248 
249 	return 0;
250 
251 give_sigsegv:
252 	force_sigsegv(sig, current);
253 	return -EFAULT;
254 }
255 
256 /* Handle restarting system calls */
257 static inline void
258 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
259 {
260 	switch (regs->r3) {
261 	case -ERESTART_RESTARTBLOCK:
262 	case -ERESTARTNOHAND:
263 		if (!has_handler)
264 			goto do_restart;
265 		regs->r3 = -EINTR;
266 		break;
267 	case -ERESTARTSYS:
268 		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
269 			regs->r3 = -EINTR;
270 			break;
271 	}
272 	/* fallthrough */
273 	case -ERESTARTNOINTR:
274 do_restart:
275 		/* offset of 4 bytes to re-execute trap (brki) instruction */
276 		regs->pc -= 4;
277 		break;
278 	}
279 }
280 
281 /*
282  * OK, we're invoking a handler
283  */
284 
285 static void
286 handle_signal(unsigned long sig, struct k_sigaction *ka,
287 		siginfo_t *info, struct pt_regs *regs)
288 {
289 	sigset_t *oldset = sigmask_to_save();
290 	int ret;
291 
292 	/* Set up the stack frame */
293 	if (ka->sa.sa_flags & SA_SIGINFO)
294 		ret = setup_rt_frame(sig, ka, info, oldset, regs);
295 	else
296 		ret = setup_rt_frame(sig, ka, NULL, oldset, regs);
297 
298 	if (ret)
299 		return;
300 
301 	signal_delivered(sig, info, ka, regs,
302 			test_thread_flag(TIF_SINGLESTEP));
303 }
304 
305 /*
306  * Note that 'init' is a special process: it doesn't get signals it doesn't
307  * want to handle. Thus you cannot kill init even with a SIGKILL even by
308  * mistake.
309  *
310  * Note that we go through the signals twice: once to check the signals that
311  * the kernel can handle, and then we build all the user-level signal handling
312  * stack-frames in one go after that.
313  */
314 static void do_signal(struct pt_regs *regs, int in_syscall)
315 {
316 	siginfo_t info;
317 	int signr;
318 	struct k_sigaction ka;
319 #ifdef DEBUG_SIG
320 	pr_info("do signal: %p %d\n", regs, in_syscall);
321 	pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
322 			regs->r12, current_thread_info()->flags);
323 #endif
324 
325 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
326 	if (signr > 0) {
327 		/* Whee! Actually deliver the signal. */
328 		if (in_syscall)
329 			handle_restart(regs, &ka, 1);
330 		handle_signal(signr, &ka, &info, regs);
331 		return;
332 	}
333 
334 	if (in_syscall)
335 		handle_restart(regs, NULL, 0);
336 
337 	/*
338 	 * If there's no signal to deliver, we just put the saved sigmask
339 	 * back.
340 	 */
341 	restore_saved_sigmask();
342 }
343 
344 asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
345 {
346 	if (test_thread_flag(TIF_SIGPENDING))
347 		do_signal(regs, in_syscall);
348 
349 	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
350 		tracehook_notify_resume(regs);
351 }
352