1/*
2 *  Port on Texas Instruments TMS320C6x architecture
3 *
4 *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
5 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
6 *
7 *  Updated for 2.6.34: Mark Salter <msalter@redhat.com>
8 *
9 *  This program is free software; you can redistribute it and/or modify
10 *  it under the terms of the GNU General Public License version 2 as
11 *  published by the Free Software Foundation.
12 */
13
14#include <linux/kernel.h>
15#include <linux/uaccess.h>
16#include <linux/syscalls.h>
17#include <linux/tracehook.h>
18
19#include <asm/ucontext.h>
20#include <asm/cacheflush.h>
21
22
23/*
24 * Do a signal return, undo the signal stack.
25 */
26
27#define RETCODE_SIZE (9 << 2)	/* 9 instructions = 36 bytes */
28
29struct rt_sigframe {
30	struct siginfo __user *pinfo;
31	void __user *puc;
32	struct siginfo info;
33	struct ucontext uc;
34	unsigned long retcode[RETCODE_SIZE >> 2];
35};
36
37static int restore_sigcontext(struct pt_regs *regs,
38			      struct sigcontext __user *sc)
39{
40	int err = 0;
41
42	/* The access_ok check was done by caller, so use __get_user here */
43#define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
44
45	COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
46	COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
47	COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
48
49	COPY(a16); COPY(a17); COPY(a18); COPY(a19);
50	COPY(a20); COPY(a21); COPY(a22); COPY(a23);
51	COPY(a24); COPY(a25); COPY(a26); COPY(a27);
52	COPY(a28); COPY(a29); COPY(a30); COPY(a31);
53	COPY(b16); COPY(b17); COPY(b18); COPY(b19);
54	COPY(b20); COPY(b21); COPY(b22); COPY(b23);
55	COPY(b24); COPY(b25); COPY(b26); COPY(b27);
56	COPY(b28); COPY(b29); COPY(b30); COPY(b31);
57
58	COPY(csr); COPY(pc);
59
60#undef COPY
61
62	return err;
63}
64
65asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
66{
67	struct rt_sigframe __user *frame;
68	sigset_t set;
69
70	/* Always make any pending restarted system calls return -EINTR */
71	current->restart_block.fn = do_no_restart_syscall;
72
73	/*
74	 * Since we stacked the signal on a dword boundary,
75	 * 'sp' should be dword aligned here.  If it's
76	 * not, then the user is trying to mess with us.
77	 */
78	if (regs->sp & 7)
79		goto badframe;
80
81	frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
82
83	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
84		goto badframe;
85	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
86		goto badframe;
87
88	set_current_blocked(&set);
89
90	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
91		goto badframe;
92
93	return regs->a4;
94
95badframe:
96	force_sig(SIGSEGV, current);
97	return 0;
98}
99
100static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
101			    unsigned long mask)
102{
103	int err = 0;
104
105	err |= __put_user(mask, &sc->sc_mask);
106
107	/* The access_ok check was done by caller, so use __put_user here */
108#define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
109
110	COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
111	COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
112	COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
113
114	COPY(a16); COPY(a17); COPY(a18); COPY(a19);
115	COPY(a20); COPY(a21); COPY(a22); COPY(a23);
116	COPY(a24); COPY(a25); COPY(a26); COPY(a27);
117	COPY(a28); COPY(a29); COPY(a30); COPY(a31);
118	COPY(b16); COPY(b17); COPY(b18); COPY(b19);
119	COPY(b20); COPY(b21); COPY(b22); COPY(b23);
120	COPY(b24); COPY(b25); COPY(b26); COPY(b27);
121	COPY(b28); COPY(b29); COPY(b30); COPY(b31);
122
123	COPY(csr); COPY(pc);
124
125#undef COPY
126
127	return err;
128}
129
130static inline void __user *get_sigframe(struct ksignal *ksig,
131					struct pt_regs *regs,
132					unsigned long framesize)
133{
134	unsigned long sp = sigsp(regs->sp, ksig);
135
136	/*
137	 * No matter what happens, 'sp' must be dword
138	 * aligned. Otherwise, nasty things will happen
139	 */
140	return (void __user *)((sp - framesize) & ~7);
141}
142
143static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
144			  struct pt_regs *regs)
145{
146	struct rt_sigframe __user *frame;
147	unsigned long __user *retcode;
148	int err = 0;
149
150	frame = get_sigframe(ksig, regs, sizeof(*frame));
151
152	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
153		return -EFAULT;
154
155	err |= __put_user(&frame->info, &frame->pinfo);
156	err |= __put_user(&frame->uc, &frame->puc);
157	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
158
159	/* Clear all the bits of the ucontext we don't use.  */
160	err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
161
162	err |= setup_sigcontext(&frame->uc.uc_mcontext,	regs, set->sig[0]);
163	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
164
165	/* Set up to return from userspace */
166	retcode = (unsigned long __user *) &frame->retcode;
167
168	/* The access_ok check was done above, so use __put_user here */
169#define COPY(x) (err |= __put_user(x, retcode++))
170
171	COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
172				/* MVK __NR_rt_sigreturn,B0 */
173	COPY(0x10000000UL);	/* SWE */
174	COPY(0x00006000UL);	/* NOP 4 */
175	COPY(0x00006000UL);	/* NOP 4 */
176	COPY(0x00006000UL);	/* NOP 4 */
177	COPY(0x00006000UL);	/* NOP 4 */
178	COPY(0x00006000UL);	/* NOP 4 */
179	COPY(0x00006000UL);	/* NOP 4 */
180	COPY(0x00006000UL);	/* NOP 4 */
181
182#undef COPY
183
184	if (err)
185		return -EFAULT;
186
187	flush_icache_range((unsigned long) &frame->retcode,
188			   (unsigned long) &frame->retcode + RETCODE_SIZE);
189
190	retcode = (unsigned long __user *) &frame->retcode;
191
192	/* Change user context to branch to signal handler */
193	regs->sp = (unsigned long) frame - 8;
194	regs->b3 = (unsigned long) retcode;
195	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
196
197	/* Give the signal number to the handler */
198	regs->a4 = ksig->sig;
199
200	/*
201	 * For realtime signals we must also set the second and third
202	 * arguments for the signal handler.
203	 *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
204	 */
205	regs->b4 = (unsigned long)&frame->info;
206	regs->a6 = (unsigned long)&frame->uc;
207
208	return 0;
209}
210
211static inline void
212handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
213{
214	switch (regs->a4) {
215	case -ERESTARTNOHAND:
216		if (!has_handler)
217			goto do_restart;
218		regs->a4 = -EINTR;
219		break;
220
221	case -ERESTARTSYS:
222		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
223			regs->a4 = -EINTR;
224			break;
225		}
226	/* fallthrough */
227	case -ERESTARTNOINTR:
228do_restart:
229		regs->a4 = regs->orig_a4;
230		regs->pc -= 4;
231		break;
232	}
233}
234
235/*
236 * handle the actual delivery of a signal to userspace
237 */
238static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
239			  int syscall)
240{
241	int ret;
242
243	/* Are we from a system call? */
244	if (syscall) {
245		/* If so, check system call restarting.. */
246		switch (regs->a4) {
247		case -ERESTART_RESTARTBLOCK:
248		case -ERESTARTNOHAND:
249			regs->a4 = -EINTR;
250			break;
251
252		case -ERESTARTSYS:
253			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
254				regs->a4 = -EINTR;
255				break;
256			}
257
258			/* fallthrough */
259		case -ERESTARTNOINTR:
260			regs->a4 = regs->orig_a4;
261			regs->pc -= 4;
262		}
263	}
264
265	/* Set up the stack frame */
266	ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
267	signal_setup_done(ret, ksig, 0);
268}
269
270/*
271 * handle a potential signal
272 */
273static void do_signal(struct pt_regs *regs, int syscall)
274{
275	struct ksignal ksig;
276
277	/* we want the common case to go fast, which is why we may in certain
278	 * cases get here from kernel mode */
279	if (!user_mode(regs))
280		return;
281
282	if (get_signal(&ksig)) {
283		handle_signal(&ksig, regs, syscall);
284		return;
285	}
286
287	/* did we come from a system call? */
288	if (syscall) {
289		/* restart the system call - no handlers present */
290		switch (regs->a4) {
291		case -ERESTARTNOHAND:
292		case -ERESTARTSYS:
293		case -ERESTARTNOINTR:
294			regs->a4 = regs->orig_a4;
295			regs->pc -= 4;
296			break;
297
298		case -ERESTART_RESTARTBLOCK:
299			regs->a4 = regs->orig_a4;
300			regs->b0 = __NR_restart_syscall;
301			regs->pc -= 4;
302			break;
303		}
304	}
305
306	/* if there's no signal to deliver, we just put the saved sigmask
307	 * back */
308	restore_saved_sigmask();
309}
310
311/*
312 * notification of userspace execution resumption
313 * - triggered by current->work.notify_resume
314 */
315asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
316				 int syscall)
317{
318	/* deal with pending signal delivery */
319	if (thread_info_flags & (1 << TIF_SIGPENDING))
320		do_signal(regs, syscall);
321
322	if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
323		clear_thread_flag(TIF_NOTIFY_RESUME);
324		tracehook_notify_resume(regs);
325	}
326}
327