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/uaccess.h>
14 #include <linux/tracehook.h>
15
16 #include <asm/cacheflush.h>
17 #include <asm/ucontext.h>
18 #include <asm/fixed_code.h>
19 #include <asm/syscall.h>
20
21 /* Location of the trace bit in SYSCFG. */
22 #define TRACE_BITS 0x0001
23
24 struct fdpic_func_descriptor {
25 unsigned long text;
26 unsigned long GOT;
27 };
28
29 struct rt_sigframe {
30 int sig;
31 struct siginfo *pinfo;
32 void *puc;
33 /* This is no longer needed by the kernel, but unfortunately userspace
34 * code expects it to be there. */
35 char retcode[8];
36 struct siginfo info;
37 struct ucontext uc;
38 };
39
40 static inline int
rt_restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc,int * pr0)41 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
42 {
43 unsigned long usp = 0;
44 int err = 0;
45
46 /* Always make any pending restarted system calls return -EINTR */
47 current->restart_block.fn = do_no_restart_syscall;
48
49 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
50
51 /* restore passed registers */
52 RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
53 RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
54 RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
55 RESTORE(p4); RESTORE(p5);
56 err |= __get_user(usp, &sc->sc_usp);
57 wrusp(usp);
58 RESTORE(a0w); RESTORE(a1w);
59 RESTORE(a0x); RESTORE(a1x);
60 RESTORE(astat);
61 RESTORE(rets);
62 RESTORE(pc);
63 RESTORE(retx);
64 RESTORE(fp);
65 RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
66 RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
67 RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
68 RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
69 RESTORE(lc0); RESTORE(lc1);
70 RESTORE(lt0); RESTORE(lt1);
71 RESTORE(lb0); RESTORE(lb1);
72 RESTORE(seqstat);
73
74 regs->orig_p0 = -1; /* disable syscall checks */
75
76 *pr0 = regs->r0;
77 return err;
78 }
79
sys_rt_sigreturn(void)80 asmlinkage int sys_rt_sigreturn(void)
81 {
82 struct pt_regs *regs = current_pt_regs();
83 unsigned long usp = rdusp();
84 struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
85 sigset_t set;
86 int r0;
87
88 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
89 goto badframe;
90 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
91 goto badframe;
92
93 set_current_blocked(&set);
94
95 if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
96 goto badframe;
97
98 if (restore_altstack(&frame->uc.uc_stack))
99 goto badframe;
100
101 return r0;
102
103 badframe:
104 force_sig(SIGSEGV, current);
105 return 0;
106 }
107
rt_setup_sigcontext(struct sigcontext * sc,struct pt_regs * regs)108 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
109 {
110 int err = 0;
111
112 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
113
114 SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
115 SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
116 SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
117 SETUP(p4); SETUP(p5);
118 err |= __put_user(rdusp(), &sc->sc_usp);
119 SETUP(a0w); SETUP(a1w);
120 SETUP(a0x); SETUP(a1x);
121 SETUP(astat);
122 SETUP(rets);
123 SETUP(pc);
124 SETUP(retx);
125 SETUP(fp);
126 SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
127 SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
128 SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
129 SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
130 SETUP(lc0); SETUP(lc1);
131 SETUP(lt0); SETUP(lt1);
132 SETUP(lb0); SETUP(lb1);
133 SETUP(seqstat);
134
135 return err;
136 }
137
get_sigframe(struct ksignal * ksig,size_t frame_size)138 static inline void *get_sigframe(struct ksignal *ksig,
139 size_t frame_size)
140 {
141 unsigned long usp = sigsp(rdusp(), ksig);
142
143 return (void *)((usp - frame_size) & -8UL);
144 }
145
146 static int
setup_rt_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)147 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
148 {
149 struct rt_sigframe *frame;
150 int err = 0;
151
152 frame = get_sigframe(ksig, sizeof(*frame));
153
154 err |= __put_user(ksig->sig, &frame->sig);
155
156 err |= __put_user(&frame->info, &frame->pinfo);
157 err |= __put_user(&frame->uc, &frame->puc);
158 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
159
160 /* Create the ucontext. */
161 err |= __put_user(0, &frame->uc.uc_flags);
162 err |= __put_user(0, &frame->uc.uc_link);
163 err |= __save_altstack(&frame->uc.uc_stack, rdusp());
164 err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
165 err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
166
167 if (err)
168 return -EFAULT;
169
170 /* Set up registers for signal handler */
171 if (current->personality & FDPIC_FUNCPTRS) {
172 struct fdpic_func_descriptor __user *funcptr =
173 (struct fdpic_func_descriptor *) ksig->ka.sa.sa_handler;
174 u32 pc, p3;
175 err |= __get_user(pc, &funcptr->text);
176 err |= __get_user(p3, &funcptr->GOT);
177 if (err)
178 return -EFAULT;
179 regs->pc = pc;
180 regs->p3 = p3;
181 } else
182 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
183 wrusp((unsigned long)frame);
184 regs->rets = SIGRETURN_STUB;
185
186 regs->r0 = frame->sig;
187 regs->r1 = (unsigned long)(&frame->info);
188 regs->r2 = (unsigned long)(&frame->uc);
189
190 return 0;
191 }
192
193 static inline void
handle_restart(struct pt_regs * regs,struct k_sigaction * ka,int has_handler)194 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
195 {
196 switch (regs->r0) {
197 case -ERESTARTNOHAND:
198 if (!has_handler)
199 goto do_restart;
200 regs->r0 = -EINTR;
201 break;
202
203 case -ERESTARTSYS:
204 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
205 regs->r0 = -EINTR;
206 break;
207 }
208 /* fallthrough */
209 case -ERESTARTNOINTR:
210 do_restart:
211 regs->p0 = regs->orig_p0;
212 regs->r0 = regs->orig_r0;
213 regs->pc -= 2;
214 break;
215
216 case -ERESTART_RESTARTBLOCK:
217 regs->p0 = __NR_restart_syscall;
218 regs->pc -= 2;
219 break;
220 }
221 }
222
223 /*
224 * OK, we're invoking a handler
225 */
226 static void
handle_signal(struct ksignal * ksig,struct pt_regs * regs)227 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
228 {
229 int ret;
230
231 /* are we from a system call? to see pt_regs->orig_p0 */
232 if (regs->orig_p0 >= 0)
233 /* If so, check system call restarting.. */
234 handle_restart(regs, &ksig->ka, 1);
235
236 /* set up the stack frame */
237 ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
238
239 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
240 }
241
242 /*
243 * Note that 'init' is a special process: it doesn't get signals it doesn't
244 * want to handle. Thus you cannot kill init even with a SIGKILL even by
245 * mistake.
246 *
247 * Note that we go through the signals twice: once to check the signals
248 * that the kernel can handle, and then we build all the user-level signal
249 * handling stack-frames in one go after that.
250 */
do_signal(struct pt_regs * regs)251 asmlinkage void do_signal(struct pt_regs *regs)
252 {
253 struct ksignal ksig;
254
255 current->thread.esp0 = (unsigned long)regs;
256
257 if (get_signal(&ksig)) {
258 /* Whee! Actually deliver the signal. */
259 handle_signal(&ksig, regs);
260 return;
261 }
262
263 /* Did we come from a system call? */
264 if (regs->orig_p0 >= 0)
265 /* Restart the system call - no handlers present */
266 handle_restart(regs, NULL, 0);
267
268 /* if there's no signal to deliver, we just put the saved sigmask
269 * back */
270 restore_saved_sigmask();
271 }
272
273 /*
274 * notification of userspace execution resumption
275 */
do_notify_resume(struct pt_regs * regs)276 asmlinkage void do_notify_resume(struct pt_regs *regs)
277 {
278 if (test_thread_flag(TIF_SIGPENDING))
279 do_signal(regs);
280
281 if (test_thread_flag(TIF_NOTIFY_RESUME)) {
282 clear_thread_flag(TIF_NOTIFY_RESUME);
283 tracehook_notify_resume(regs);
284 }
285 }
286
287