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Linux/arch/csky/kernel/signal.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 
  3 #include <linux/signal.h>
  4 #include <linux/uaccess.h>
  5 #include <linux/syscalls.h>
  6 #include <linux/tracehook.h>
  7 
  8 #include <asm/traps.h>
  9 #include <asm/ucontext.h>
 10 #include <asm/vdso.h>
 11 
 12 #include <abi/regdef.h>
 13 
 14 #ifdef CONFIG_CPU_HAS_FPU
 15 #include <abi/fpu.h>
 16 static int restore_fpu_state(struct sigcontext __user *sc)
 17 {
 18         int err = 0;
 19         struct user_fp user_fp;
 20 
 21         err = __copy_from_user(&user_fp, &sc->sc_user_fp, sizeof(user_fp));
 22 
 23         restore_from_user_fp(&user_fp);
 24 
 25         return err;
 26 }
 27 
 28 static int save_fpu_state(struct sigcontext __user *sc)
 29 {
 30         struct user_fp user_fp;
 31 
 32         save_to_user_fp(&user_fp);
 33 
 34         return __copy_to_user(&sc->sc_user_fp, &user_fp, sizeof(user_fp));
 35 }
 36 #else
 37 #define restore_fpu_state(sigcontext)   (0)
 38 #define save_fpu_state(sigcontext)      (0)
 39 #endif
 40 
 41 struct rt_sigframe {
 42         /*
 43          * pad[3] is compatible with the same struct defined in
 44          * gcc/libgcc/config/csky/linux-unwind.h
 45          */
 46         int pad[3];
 47         struct siginfo info;
 48         struct ucontext uc;
 49 };
 50 
 51 static long restore_sigcontext(struct pt_regs *regs,
 52         struct sigcontext __user *sc)
 53 {
 54         int err = 0;
 55 
 56         /* sc_pt_regs is structured the same as the start of pt_regs */
 57         err |= __copy_from_user(regs, &sc->sc_pt_regs, sizeof(struct pt_regs));
 58 
 59         /* Restore the floating-point state. */
 60         err |= restore_fpu_state(sc);
 61 
 62         return err;
 63 }
 64 
 65 SYSCALL_DEFINE0(rt_sigreturn)
 66 {
 67         struct pt_regs *regs = current_pt_regs();
 68         struct rt_sigframe __user *frame;
 69         sigset_t set;
 70 
 71         /* Always make any pending restarted system calls return -EINTR */
 72         current->restart_block.fn = do_no_restart_syscall;
 73 
 74         frame = (struct rt_sigframe __user *)regs->usp;
 75 
 76         if (!access_ok(frame, sizeof(*frame)))
 77                 goto badframe;
 78 
 79         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 80                 goto badframe;
 81 
 82         set_current_blocked(&set);
 83 
 84         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 85                 goto badframe;
 86 
 87         if (restore_altstack(&frame->uc.uc_stack))
 88                 goto badframe;
 89 
 90         return regs->a0;
 91 
 92 badframe:
 93         force_sig(SIGSEGV);
 94         return 0;
 95 }
 96 
 97 static int setup_sigcontext(struct rt_sigframe __user *frame,
 98         struct pt_regs *regs)
 99 {
100         struct sigcontext __user *sc = &frame->uc.uc_mcontext;
101         int err = 0;
102 
103         err |= __copy_to_user(&sc->sc_pt_regs, regs, sizeof(struct pt_regs));
104         err |= save_fpu_state(sc);
105 
106         return err;
107 }
108 
109 static inline void __user *get_sigframe(struct ksignal *ksig,
110         struct pt_regs *regs, size_t framesize)
111 {
112         unsigned long sp;
113         /* Default to using normal stack */
114         sp = regs->usp;
115 
116         /*
117          * If we are on the alternate signal stack and would overflow it, don't.
118          * Return an always-bogus address instead so we will die with SIGSEGV.
119          */
120         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
121                 return (void __user __force *)(-1UL);
122 
123         /* This is the X/Open sanctioned signal stack switching. */
124         sp = sigsp(sp, ksig) - framesize;
125 
126         /* Align the stack frame. */
127         sp &= -8UL;
128 
129         return (void __user *)sp;
130 }
131 
132 static int
133 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
134 {
135         struct rt_sigframe *frame;
136         int err = 0;
137         struct csky_vdso *vdso = current->mm->context.vdso;
138 
139         frame = get_sigframe(ksig, regs, sizeof(*frame));
140         if (!access_ok(frame, sizeof(*frame)))
141                 return -EFAULT;
142 
143         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
144 
145         /* Create the ucontext. */
146         err |= __put_user(0, &frame->uc.uc_flags);
147         err |= __put_user(NULL, &frame->uc.uc_link);
148         err |= __save_altstack(&frame->uc.uc_stack, regs->usp);
149         err |= setup_sigcontext(frame, regs);
150         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
151         if (err)
152                 return -EFAULT;
153 
154         /* Set up to return from userspace. */
155         regs->lr = (unsigned long)(vdso->rt_signal_retcode);
156 
157         /*
158          * Set up registers for signal handler.
159          * Registers that we don't modify keep the value they had from
160          * user-space at the time we took the signal.
161          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
162          * since some things rely on this (e.g. glibc's debug/segfault.c).
163          */
164         regs->pc  = (unsigned long)ksig->ka.sa.sa_handler;
165         regs->usp = (unsigned long)frame;
166         regs->a0  = ksig->sig;                          /* a0: signal number */
167         regs->a1  = (unsigned long)(&(frame->info));    /* a1: siginfo pointer */
168         regs->a2  = (unsigned long)(&(frame->uc));      /* a2: ucontext pointer */
169 
170         return 0;
171 }
172 
173 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
174 {
175         sigset_t *oldset = sigmask_to_save();
176         int ret;
177 
178         rseq_signal_deliver(ksig, regs);
179 
180         /* Are we from a system call? */
181         if (in_syscall(regs)) {
182                 /* Avoid additional syscall restarting via ret_from_exception */
183                 forget_syscall(regs);
184 
185                 /* If so, check system call restarting.. */
186                 switch (regs->a0) {
187                 case -ERESTART_RESTARTBLOCK:
188                 case -ERESTARTNOHAND:
189                         regs->a0 = -EINTR;
190                         break;
191 
192                 case -ERESTARTSYS:
193                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
194                                 regs->a0 = -EINTR;
195                                 break;
196                         }
197                         /* fallthrough */
198                 case -ERESTARTNOINTR:
199                         regs->a0 = regs->orig_a0;
200                         regs->pc -= TRAP0_SIZE;
201                         break;
202                 }
203         }
204 
205         /* Set up the stack frame */
206         ret = setup_rt_frame(ksig, oldset, regs);
207 
208         signal_setup_done(ret, ksig, 0);
209 }
210 
211 static void do_signal(struct pt_regs *regs)
212 {
213         struct ksignal ksig;
214 
215         if (get_signal(&ksig)) {
216                 /* Actually deliver the signal */
217                 handle_signal(&ksig, regs);
218                 return;
219         }
220 
221         /* Did we come from a system call? */
222         if (in_syscall(regs)) {
223                 /* Avoid additional syscall restarting via ret_from_exception */
224                 forget_syscall(regs);
225 
226                 /* Restart the system call - no handlers present */
227                 switch (regs->a0) {
228                 case -ERESTARTNOHAND:
229                 case -ERESTARTSYS:
230                 case -ERESTARTNOINTR:
231                         regs->a0 = regs->orig_a0;
232                         regs->pc -= TRAP0_SIZE;
233                         break;
234                 case -ERESTART_RESTARTBLOCK:
235                         regs->a0 = regs->orig_a0;
236                         regs_syscallid(regs) = __NR_restart_syscall;
237                         regs->pc -= TRAP0_SIZE;
238                         break;
239                 }
240         }
241 
242         /*
243          * If there is no signal to deliver, we just put the saved
244          * sigmask back.
245          */
246         restore_saved_sigmask();
247 }
248 
249 /*
250  * notification of userspace execution resumption
251  * - triggered by the _TIF_WORK_MASK flags
252  */
253 asmlinkage void do_notify_resume(struct pt_regs *regs,
254         unsigned long thread_info_flags)
255 {
256         if (thread_info_flags & _TIF_UPROBE)
257                 uprobe_notify_resume(regs);
258 
259         /* Handle pending signal delivery */
260         if (thread_info_flags & _TIF_SIGPENDING)
261                 do_signal(regs);
262 
263         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
264                 clear_thread_flag(TIF_NOTIFY_RESUME);
265                 tracehook_notify_resume(regs);
266                 rseq_handle_notify_resume(NULL, regs);
267         }
268 }
269 

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