arch/riscv/kernel/signal.c

   1 /*
   2  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   3  *  Chen Liqin <liqin.chen@sunplusct.com>
   4  *  Lennox Wu <lennox.wu@sunplusct.com>
   5  * Copyright (C) 2012 Regents of the University of California
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see the file COPYING, or write
  19  * to the Free Software Foundation, Inc.,
  20  */
  21
  22 #include <linux/signal.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/tracehook.h>
  26 #include <linux/linkage.h>
  27
  28 #include <asm/ucontext.h>
  29 #include <asm/vdso.h>
  30 #include <asm/switch_to.h>
  31 #include <asm/csr.h>
  32
  33 #define DEBUG_SIG 0
  34
  35 struct rt_sigframe {
  36         struct siginfo info;
  37         struct ucontext uc;
  38 };
  39
  40 static long restore_d_state(struct pt_regs *regs,
  41         struct __riscv_d_ext_state __user *state)
  42 {
  43         long err;
  44         err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
  45         if (likely(!err))
  46                 fstate_restore(current, regs);
  47         return err;
  48 }
  49
  50 static long save_d_state(struct pt_regs *regs,
  51         struct __riscv_d_ext_state __user *state)
  52 {
  53         fstate_save(current, regs);
  54         return __copy_to_user(state, &current->thread.fstate, sizeof(*state));
  55 }
  56
  57 static long restore_sigcontext(struct pt_regs *regs,
  58         struct sigcontext __user *sc)
  59 {
  60         long err;
  61         size_t i;
  62         /* sc_regs is structured the same as the start of pt_regs */
  63         err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
  64         if (unlikely(err))
  65                 return err;
  66         /* Restore the floating-point state. */
  67         err = restore_d_state(regs, &sc->sc_fpregs.d);
  68         if (unlikely(err))
  69                 return err;
  70         /* We support no other extension state at this time. */
  71         for (i = 0; i < ARRAY_SIZE(sc->sc_fpregs.q.reserved); i++) {
  72                 u32 value;
  73                 err = __get_user(value, &sc->sc_fpregs.q.reserved[i]);
  74                 if (unlikely(err))
  75                         break;
  76                 if (value != 0)
  77                         return -EINVAL;
  78         }
  79         return err;
  80 }
  81
  82 SYSCALL_DEFINE0(rt_sigreturn)
  83 {
  84         struct pt_regs *regs = current_pt_regs();
  85         struct rt_sigframe __user *frame;
  86         struct task_struct *task;
  87         sigset_t set;
  88
  89         /* Always make any pending restarted system calls return -EINTR */
  90         current->restart_block.fn = do_no_restart_syscall;
  91
  92         frame = (struct rt_sigframe __user *)regs->sp;
  93
  94         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  95                 goto badframe;
  96
  97         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  98                 goto badframe;
  99
 100         set_current_blocked(&set);
 101
 102         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 103                 goto badframe;
 104
 105         if (restore_altstack(&frame->uc.uc_stack))
 106                 goto badframe;
 107
 108         return regs->a0;
 109
 110 badframe:
 111         task = current;
 112         if (show_unhandled_signals) {
 113                 pr_info_ratelimited(
 114                         "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
 115                         task->comm, task_pid_nr(task), __func__,
 116                         frame, (void *)regs->sepc, (void *)regs->sp);
 117         }
 118         force_sig(SIGSEGV, task);
 119         return 0;
 120 }
 121
 122 static long setup_sigcontext(struct rt_sigframe __user *frame,
 123         struct pt_regs *regs)
 124 {
 125         struct sigcontext __user *sc = &frame->uc.uc_mcontext;
 126         long err;
 127         size_t i;
 128         /* sc_regs is structured the same as the start of pt_regs */
 129         err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
 130         /* Save the floating-point state. */
 131         err |= save_d_state(regs, &sc->sc_fpregs.d);
 132         /* We support no other extension state at this time. */
 133         for (i = 0; i < ARRAY_SIZE(sc->sc_fpregs.q.reserved); i++)
 134                 err |= __put_user(0, &sc->sc_fpregs.q.reserved[i]);
 135         return err;
 136 }
 137
 138 static inline void __user *get_sigframe(struct ksignal *ksig,
 139         struct pt_regs *regs, size_t framesize)
 140 {
 141         unsigned long sp;
 142         /* Default to using normal stack */
 143         sp = regs->sp;
 144
 145         /*
 146          * If we are on the alternate signal stack and would overflow it, don't.
 147          * Return an always-bogus address instead so we will die with SIGSEGV.
 148          */
 149         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 150                 return (void __user __force *)(-1UL);
 151
 152         /* This is the X/Open sanctioned signal stack switching. */
 153         sp = sigsp(sp, ksig) - framesize;
 154
 155         /* Align the stack frame. */
 156         sp &= ~0xfUL;
 157
 158         return (void __user *)sp;
 159 }
 160
 161
 162 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 163         struct pt_regs *regs)
 164 {
 165         struct rt_sigframe __user *frame;
 166         long err = 0;
 167
 168         frame = get_sigframe(ksig, regs, sizeof(*frame));
 169         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 170                 return -EFAULT;
 171
 172         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 173
 174         /* Create the ucontext. */
 175         err |= __put_user(0, &frame->uc.uc_flags);
 176         err |= __put_user(NULL, &frame->uc.uc_link);
 177         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 178         err |= setup_sigcontext(frame, regs);
 179         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 180         if (err)
 181                 return -EFAULT;
 182
 183         /* Set up to return from userspace. */
 184         regs->ra = (unsigned long)VDSO_SYMBOL(
 185                 current->mm->context.vdso, rt_sigreturn);
 186
 187         /*
 188          * Set up registers for signal handler.
 189          * Registers that we don't modify keep the value they had from
 190          * user-space at the time we took the signal.
 191          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 192          * since some things rely on this (e.g. glibc's debug/segfault.c).
 193          */
 194         regs->sepc = (unsigned long)ksig->ka.sa.sa_handler;
 195         regs->sp = (unsigned long)frame;
 196         regs->a0 = ksig->sig;                     /* a0: signal number */
 197         regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
 198         regs->a2 = (unsigned long)(&frame->uc);   /* a2: ucontext pointer */
 199
 200 #if DEBUG_SIG
 201         pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
 202                 current->comm, task_pid_nr(current), ksig->sig,
 203                 (void *)regs->sepc, (void *)regs->ra, frame);
 204 #endif
 205
 206         return 0;
 207 }
 208
 209 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 210 {
 211         sigset_t *oldset = sigmask_to_save();
 212         int ret;
 213
 214         /* Are we from a system call? */
 215         if (regs->scause == EXC_SYSCALL) {
 216                 /* If so, check system call restarting.. */
 217                 switch (regs->a0) {
 218                 case -ERESTART_RESTARTBLOCK:
 219                 case -ERESTARTNOHAND:
 220                         regs->a0 = -EINTR;
 221                         break;
 222
 223                 case -ERESTARTSYS:
 224                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 225                                 regs->a0 = -EINTR;
 226                                 break;
 227                         }
 228                         /* fallthrough */
 229                 case -ERESTARTNOINTR:
 230                         regs->a0 = regs->orig_a0;
 231                         regs->sepc -= 0x4;
 232                         break;
 233                 }
 234         }
 235
 236         /* Set up the stack frame */
 237         ret = setup_rt_frame(ksig, oldset, regs);
 238
 239         signal_setup_done(ret, ksig, 0);
 240 }
 241
 242 static void do_signal(struct pt_regs *regs)
 243 {
 244         struct ksignal ksig;
 245
 246         if (get_signal(&ksig)) {
 247                 /* Actually deliver the signal */
 248                 handle_signal(&ksig, regs);
 249                 return;
 250         }
 251
 252         /* Did we come from a system call? */
 253         if (regs->scause == EXC_SYSCALL) {
 254                 /* Restart the system call - no handlers present */
 255                 switch (regs->a0) {
 256                 case -ERESTARTNOHAND:
 257                 case -ERESTARTSYS:
 258                 case -ERESTARTNOINTR:
 259                         regs->a0 = regs->orig_a0;
 260                         regs->sepc -= 0x4;
 261                         break;
 262                 case -ERESTART_RESTARTBLOCK:
 263                         regs->a0 = regs->orig_a0;
 264                         regs->a7 = __NR_restart_syscall;
 265                         regs->sepc -= 0x4;
 266                         break;
 267                 }
 268         }
 269
 270         /*
 271          * If there is no signal to deliver, we just put the saved
 272          * sigmask back.
 273          */
 274         restore_saved_sigmask();
 275 }
 276
 277 /*
 278  * notification of userspace execution resumption
 279  * - triggered by the _TIF_WORK_MASK flags
 280  */
 281 asmlinkage void do_notify_resume(struct pt_regs *regs,
 282         unsigned long thread_info_flags)
 283 {
 284         /* Handle pending signal delivery */
 285         if (thread_info_flags & _TIF_SIGPENDING)
 286                 do_signal(regs);
 287
 288         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 289                 clear_thread_flag(TIF_NOTIFY_RESUME);
 290                 tracehook_notify_resume(regs);
 291         }
 292 }