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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd. | |
3 | ||
4 | #include <linux/sched.h> | |
5 | #include <linux/mm.h> | |
6 | #include <linux/kernel.h> | |
7 | #include <linux/signal.h> | |
8 | #include <linux/syscalls.h> | |
9 | #include <linux/errno.h> | |
10 | #include <linux/wait.h> | |
11 | #include <linux/ptrace.h> | |
12 | #include <linux/unistd.h> | |
13 | #include <linux/stddef.h> | |
14 | #include <linux/highuid.h> | |
15 | #include <linux/personality.h> | |
16 | #include <linux/tty.h> | |
17 | #include <linux/binfmts.h> | |
18 | #include <linux/tracehook.h> | |
19 | #include <linux/freezer.h> | |
20 | #include <linux/uaccess.h> | |
21 | ||
22 | #include <asm/setup.h> | |
23 | #include <asm/pgtable.h> | |
24 | #include <asm/traps.h> | |
25 | #include <asm/ucontext.h> | |
26 | #include <asm/vdso.h> | |
27 | ||
28 | #include <abi/regdef.h> | |
29 | ||
30 | #ifdef CONFIG_CPU_HAS_FPU | |
31 | #include <abi/fpu.h> | |
32 | ||
33 | static int restore_fpu_state(struct sigcontext *sc) | |
34 | { | |
35 | int err = 0; | |
36 | struct user_fp user_fp; | |
37 | ||
38 | err = copy_from_user(&user_fp, &sc->sc_user_fp, sizeof(user_fp)); | |
39 | ||
40 | restore_from_user_fp(&user_fp); | |
41 | ||
42 | return err; | |
43 | } | |
44 | ||
45 | static int save_fpu_state(struct sigcontext *sc) | |
46 | { | |
47 | struct user_fp user_fp; | |
48 | ||
49 | save_to_user_fp(&user_fp); | |
50 | ||
51 | return copy_to_user(&sc->sc_user_fp, &user_fp, sizeof(user_fp)); | |
52 | } | |
53 | #else | |
54 | static inline int restore_fpu_state(struct sigcontext *sc) { return 0; } | |
55 | static inline int save_fpu_state(struct sigcontext *sc) { return 0; } | |
56 | #endif | |
57 | ||
58 | struct rt_sigframe { | |
59 | int sig; | |
60 | struct siginfo *pinfo; | |
61 | void *puc; | |
62 | struct siginfo info; | |
63 | struct ucontext uc; | |
64 | }; | |
65 | ||
66 | static int | |
67 | restore_sigframe(struct pt_regs *regs, | |
68 | struct sigcontext *sc, int *pr2) | |
69 | { | |
70 | int err = 0; | |
71 | ||
72 | /* Always make any pending restarted system calls return -EINTR */ | |
73 | current_thread_info()->task->restart_block.fn = do_no_restart_syscall; | |
74 | ||
75 | err |= copy_from_user(regs, &sc->sc_pt_regs, sizeof(struct pt_regs)); | |
76 | ||
77 | err |= restore_fpu_state(sc); | |
78 | ||
79 | *pr2 = regs->a0; | |
80 | return err; | |
81 | } | |
82 | ||
83 | asmlinkage int | |
84 | do_rt_sigreturn(void) | |
85 | { | |
86 | sigset_t set; | |
87 | int a0; | |
88 | struct pt_regs *regs = current_pt_regs(); | |
89 | struct rt_sigframe *frame = (struct rt_sigframe *)(regs->usp); | |
90 | ||
96d4f267 | 91 | if (!access_ok(frame, sizeof(*frame))) |
e9564df7 GR |
92 | goto badframe; |
93 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) | |
94 | goto badframe; | |
95 | ||
96 | sigdelsetmask(&set, (sigmask(SIGKILL) | sigmask(SIGSTOP))); | |
97 | spin_lock_irq(¤t->sighand->siglock); | |
98 | current->blocked = set; | |
99 | recalc_sigpending(); | |
100 | spin_unlock_irq(¤t->sighand->siglock); | |
101 | ||
102 | if (restore_sigframe(regs, &frame->uc.uc_mcontext, &a0)) | |
103 | goto badframe; | |
104 | ||
105 | return a0; | |
106 | ||
107 | badframe: | |
108 | force_sig(SIGSEGV, current); | |
109 | return 0; | |
110 | } | |
111 | ||
112 | static int setup_sigframe(struct sigcontext *sc, struct pt_regs *regs) | |
113 | { | |
114 | int err = 0; | |
115 | ||
116 | err |= copy_to_user(&sc->sc_pt_regs, regs, sizeof(struct pt_regs)); | |
117 | err |= save_fpu_state(sc); | |
118 | ||
119 | return err; | |
120 | } | |
121 | ||
122 | static inline void * | |
123 | get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size) | |
124 | { | |
125 | unsigned long usp; | |
126 | ||
127 | /* Default to using normal stack. */ | |
128 | usp = regs->usp; | |
129 | ||
130 | /* This is the X/Open sanctioned signal stack switching. */ | |
131 | if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(usp)) { | |
132 | if (!on_sig_stack(usp)) | |
133 | usp = current->sas_ss_sp + current->sas_ss_size; | |
134 | } | |
135 | return (void *)((usp - frame_size) & -8UL); | |
136 | } | |
137 | ||
138 | static int | |
139 | setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) | |
140 | { | |
141 | struct rt_sigframe *frame; | |
142 | int err = 0; | |
143 | ||
144 | struct csky_vdso *vdso = current->mm->context.vdso; | |
145 | ||
146 | frame = get_sigframe(&ksig->ka, regs, sizeof(*frame)); | |
147 | if (!frame) | |
148 | return 1; | |
149 | ||
150 | err |= __put_user(ksig->sig, &frame->sig); | |
151 | err |= __put_user(&frame->info, &frame->pinfo); | |
152 | err |= __put_user(&frame->uc, &frame->puc); | |
153 | err |= copy_siginfo_to_user(&frame->info, &ksig->info); | |
154 | ||
155 | /* Create the ucontext. */ | |
156 | err |= __put_user(0, &frame->uc.uc_flags); | |
157 | err |= __put_user(0, &frame->uc.uc_link); | |
158 | err |= __put_user((void *)current->sas_ss_sp, | |
159 | &frame->uc.uc_stack.ss_sp); | |
160 | err |= __put_user(sas_ss_flags(regs->usp), | |
161 | &frame->uc.uc_stack.ss_flags); | |
162 | err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); | |
163 | err |= setup_sigframe(&frame->uc.uc_mcontext, regs); | |
164 | err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); | |
165 | ||
166 | if (err) | |
167 | goto give_sigsegv; | |
168 | ||
169 | /* Set up registers for signal handler */ | |
170 | regs->usp = (unsigned long)frame; | |
171 | regs->pc = (unsigned long)ksig->ka.sa.sa_handler; | |
172 | regs->lr = (unsigned long)vdso->rt_signal_retcode; | |
173 | ||
174 | adjust_stack: | |
175 | regs->a0 = ksig->sig; /* first arg is signo */ | |
176 | regs->a1 = (unsigned long)(&(frame->info)); | |
177 | regs->a2 = (unsigned long)(&(frame->uc)); | |
178 | return err; | |
179 | ||
180 | give_sigsegv: | |
181 | if (ksig->sig == SIGSEGV) | |
182 | ksig->ka.sa.sa_handler = SIG_DFL; | |
183 | force_sig(SIGSEGV, current); | |
184 | goto adjust_stack; | |
185 | } | |
186 | ||
187 | /* | |
188 | * OK, we're invoking a handler | |
189 | */ | |
190 | static int | |
191 | handle_signal(struct ksignal *ksig, struct pt_regs *regs) | |
192 | { | |
193 | int ret; | |
194 | sigset_t *oldset = sigmask_to_save(); | |
195 | ||
196 | /* | |
197 | * set up the stack frame, regardless of SA_SIGINFO, | |
198 | * and pass info anyway. | |
199 | */ | |
200 | ret = setup_rt_frame(ksig, oldset, regs); | |
201 | ||
202 | if (ret != 0) { | |
203 | force_sigsegv(ksig->sig, current); | |
204 | return ret; | |
205 | } | |
206 | ||
207 | /* Block the signal if we were successful. */ | |
208 | spin_lock_irq(¤t->sighand->siglock); | |
209 | sigorsets(¤t->blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); | |
210 | if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) | |
211 | sigaddset(¤t->blocked, ksig->sig); | |
212 | recalc_sigpending(); | |
213 | spin_unlock_irq(¤t->sighand->siglock); | |
214 | ||
215 | return 0; | |
216 | } | |
217 | ||
218 | /* | |
219 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
220 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
221 | * mistake. | |
222 | * | |
223 | * Note that we go through the signals twice: once to check the signals | |
224 | * that the kernel can handle, and then we build all the user-level signal | |
225 | * handling stack-frames in one go after that. | |
226 | */ | |
227 | static void do_signal(struct pt_regs *regs, int syscall) | |
228 | { | |
229 | unsigned int retval = 0, continue_addr = 0, restart_addr = 0; | |
230 | struct ksignal ksig; | |
231 | ||
232 | /* | |
233 | * We want the common case to go fast, which | |
234 | * is why we may in certain cases get here from | |
235 | * kernel mode. Just return without doing anything | |
236 | * if so. | |
237 | */ | |
238 | if (!user_mode(regs)) | |
239 | return; | |
240 | ||
241 | current->thread.esp0 = (unsigned long)regs; | |
242 | ||
243 | /* | |
244 | * If we were from a system call, check for system call restarting... | |
245 | */ | |
246 | if (syscall) { | |
247 | continue_addr = regs->pc; | |
248 | #if defined(__CSKYABIV2__) | |
249 | restart_addr = continue_addr - 4; | |
250 | #else | |
251 | restart_addr = continue_addr - 2; | |
252 | #endif | |
253 | retval = regs->a0; | |
254 | ||
255 | /* | |
256 | * Prepare for system call restart. We do this here so that a | |
257 | * debugger will see the already changed. | |
258 | */ | |
259 | switch (retval) { | |
260 | case -ERESTARTNOHAND: | |
261 | case -ERESTARTSYS: | |
262 | case -ERESTARTNOINTR: | |
263 | regs->a0 = regs->orig_a0; | |
264 | regs->pc = restart_addr; | |
265 | break; | |
266 | case -ERESTART_RESTARTBLOCK: | |
267 | regs->a0 = -EINTR; | |
268 | break; | |
269 | } | |
270 | } | |
271 | ||
272 | if (try_to_freeze()) | |
273 | goto no_signal; | |
274 | ||
275 | /* | |
276 | * Get the signal to deliver. When running under ptrace, at this | |
277 | * point the debugger may change all our registers ... | |
278 | */ | |
279 | if (get_signal(&ksig)) { | |
280 | /* | |
281 | * Depending on the signal settings we may need to revert the | |
282 | * decision to restart the system call. But skip this if a | |
283 | * debugger has chosen to restart at a different PC. | |
284 | */ | |
285 | if (regs->pc == restart_addr) { | |
286 | if (retval == -ERESTARTNOHAND || | |
287 | (retval == -ERESTARTSYS && | |
288 | !(ksig.ka.sa.sa_flags & SA_RESTART))) { | |
289 | regs->a0 = -EINTR; | |
290 | regs->pc = continue_addr; | |
291 | } | |
292 | } | |
293 | ||
294 | /* Whee! Actually deliver the signal. */ | |
295 | if (handle_signal(&ksig, regs) == 0) { | |
296 | /* | |
297 | * A signal was successfully delivered; the saved | |
298 | * sigmask will have been stored in the signal frame, | |
299 | * and will be restored by sigreturn, so we can simply | |
300 | * clear the TIF_RESTORE_SIGMASK flag. | |
301 | */ | |
302 | if (test_thread_flag(TIF_RESTORE_SIGMASK)) | |
303 | clear_thread_flag(TIF_RESTORE_SIGMASK); | |
304 | } | |
305 | return; | |
306 | } | |
307 | ||
308 | no_signal: | |
309 | if (syscall) { | |
310 | /* | |
311 | * Handle restarting a different system call. As above, | |
312 | * if a debugger has chosen to restart at a different PC, | |
313 | * ignore the restart. | |
314 | */ | |
315 | if (retval == -ERESTART_RESTARTBLOCK | |
316 | && regs->pc == continue_addr) { | |
317 | #if defined(__CSKYABIV2__) | |
318 | regs->regs[3] = __NR_restart_syscall; | |
319 | regs->pc -= 4; | |
320 | #else | |
321 | regs->regs[9] = __NR_restart_syscall; | |
322 | regs->pc -= 2; | |
323 | #endif | |
324 | } | |
325 | ||
326 | /* | |
327 | * If there's no signal to deliver, we just put the saved | |
328 | * sigmask back. | |
329 | */ | |
330 | if (test_thread_flag(TIF_RESTORE_SIGMASK)) { | |
331 | clear_thread_flag(TIF_RESTORE_SIGMASK); | |
332 | sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); | |
333 | } | |
334 | } | |
335 | } | |
336 | ||
337 | asmlinkage void | |
338 | do_notify_resume(unsigned int thread_flags, struct pt_regs *regs, int syscall) | |
339 | { | |
340 | if (thread_flags & _TIF_SIGPENDING) | |
341 | do_signal(regs, syscall); | |
342 | ||
343 | if (thread_flags & _TIF_NOTIFY_RESUME) { | |
344 | clear_thread_flag(TIF_NOTIFY_RESUME); | |
345 | tracehook_notify_resume(regs); | |
346 | } | |
347 | } |