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Linux/arch/csky/kernel/signal.c

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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 
 91         if (!access_ok(frame, sizeof(*frame)))
 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(&current->sighand->siglock);
 98         current->blocked = set;
 99         recalc_sigpending();
100         spin_unlock_irq(&current->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(&current->sighand->siglock);
209         sigorsets(&current->blocked, &current->blocked, &ksig->ka.sa.sa_mask);
210         if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
211                 sigaddset(&current->blocked, ksig->sig);
212         recalc_sigpending();
213         spin_unlock_irq(&current->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         /*
242          * If we were from a system call, check for system call restarting...
243          */
244         if (syscall) {
245                 continue_addr = regs->pc;
246 #if defined(__CSKYABIV2__)
247                 restart_addr = continue_addr - 4;
248 #else
249                 restart_addr = continue_addr - 2;
250 #endif
251                 retval = regs->a0;
252 
253                 /*
254                  * Prepare for system call restart.  We do this here so that a
255                  * debugger will see the already changed.
256                  */
257                 switch (retval) {
258                 case -ERESTARTNOHAND:
259                 case -ERESTARTSYS:
260                 case -ERESTARTNOINTR:
261                         regs->a0 = regs->orig_a0;
262                         regs->pc = restart_addr;
263                         break;
264                 case -ERESTART_RESTARTBLOCK:
265                         regs->a0 = -EINTR;
266                         break;
267                 }
268         }
269 
270         if (try_to_freeze())
271                 goto no_signal;
272 
273         /*
274          * Get the signal to deliver.  When running under ptrace, at this
275          * point the debugger may change all our registers ...
276          */
277         if (get_signal(&ksig)) {
278                 /*
279                  * Depending on the signal settings we may need to revert the
280                  * decision to restart the system call.  But skip this if a
281                  * debugger has chosen to restart at a different PC.
282                  */
283                 if (regs->pc == restart_addr) {
284                         if (retval == -ERESTARTNOHAND ||
285                             (retval == -ERESTARTSYS &&
286                              !(ksig.ka.sa.sa_flags & SA_RESTART))) {
287                                 regs->a0 = -EINTR;
288                                 regs->pc = continue_addr;
289                         }
290                 }
291 
292                 /* Whee!  Actually deliver the signal.  */
293                 if (handle_signal(&ksig, regs) == 0) {
294                         /*
295                          * A signal was successfully delivered; the saved
296                          * sigmask will have been stored in the signal frame,
297                          * and will be restored by sigreturn, so we can simply
298                          * clear the TIF_RESTORE_SIGMASK flag.
299                          */
300                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
301                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
302                 }
303                 return;
304         }
305 
306 no_signal:
307         if (syscall) {
308                 /*
309                  * Handle restarting a different system call.  As above,
310                  * if a debugger has chosen to restart at a different PC,
311                  * ignore the restart.
312                  */
313                 if (retval == -ERESTART_RESTARTBLOCK
314                                 && regs->pc == continue_addr) {
315 #if defined(__CSKYABIV2__)
316                         regs->regs[3] = __NR_restart_syscall;
317                         regs->pc -= 4;
318 #else
319                         regs->regs[9] = __NR_restart_syscall;
320                         regs->pc -= 2;
321 #endif
322                 }
323 
324                 /*
325                  * If there's no signal to deliver, we just put the saved
326                  * sigmask back.
327                  */
328                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
329                         clear_thread_flag(TIF_RESTORE_SIGMASK);
330                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
331                 }
332         }
333 }
334 
335 asmlinkage void
336 do_notify_resume(unsigned int thread_flags, struct pt_regs *regs, int syscall)
337 {
338         if (thread_flags & _TIF_SIGPENDING)
339                 do_signal(regs, syscall);
340 
341         if (thread_flags & _TIF_NOTIFY_RESUME) {
342                 clear_thread_flag(TIF_NOTIFY_RESUME);
343                 tracehook_notify_resume(regs);
344         }
345 }
346 

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