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 #ifdef CONFIG_FPU
  41 static long restore_fp_state(struct pt_regs *regs,
  42                              union __riscv_fp_state *sc_fpregs)
  43 {
  44         long err;
  45         struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
  46         size_t i;
  47
  48         err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
  49         if (unlikely(err))
  50                 return err;
  51
  52         fstate_restore(current, regs);
  53
  54         /* We support no other extension state at this time. */
  55         for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
  56                 u32 value;
  57
  58                 err = __get_user(value, &sc_fpregs->q.reserved[i]);
  59                 if (unlikely(err))
  60                         break;
  61                 if (value != 0)
  62                         return -EINVAL;
  63         }
  64
  65         return err;
  66 }
  67
  68 static long save_fp_state(struct pt_regs *regs,
  69                           union __riscv_fp_state *sc_fpregs)
  70 {
  71         long err;
  72         struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
  73         size_t i;
  74
  75         fstate_save(current, regs);
  76         err = __copy_to_user(state, &current->thread.fstate, sizeof(*state));
  77         if (unlikely(err))
  78                 return err;
  79
  80         /* We support no other extension state at this time. */
  81         for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
  82                 err = __put_user(0, &sc_fpregs->q.reserved[i]);
  83                 if (unlikely(err))
  84                         break;
  85         }
  86
  87         return err;
  88 }
  89 #else
  90 #define save_fp_state(task, regs) (0)
  91 #define restore_fp_state(task, regs) (0)
  92 #endif
  93
  94 static long restore_sigcontext(struct pt_regs *regs,
  95         struct sigcontext __user *sc)
  96 {
  97         long err;
  98         /* sc_regs is structured the same as the start of pt_regs */
  99         err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
 100         /* Restore the floating-point state. */
 101         if (has_fpu)
 102                 err |= restore_fp_state(regs, &sc->sc_fpregs);
 103         return err;
 104 }
 105
 106 SYSCALL_DEFINE0(rt_sigreturn)
 107 {
 108         struct pt_regs *regs = current_pt_regs();
 109         struct rt_sigframe __user *frame;
 110         struct task_struct *task;
 111         sigset_t set;
 112
 113         /* Always make any pending restarted system calls return -EINTR */
 114         current->restart_block.fn = do_no_restart_syscall;
 115
 116         frame = (struct rt_sigframe __user *)regs->sp;
 117
 118         if (!access_ok(frame, sizeof(*frame)))
 119                 goto badframe;
 120
 121         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 122                 goto badframe;
 123
 124         set_current_blocked(&set);
 125
 126         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 127                 goto badframe;
 128
 129         if (restore_altstack(&frame->uc.uc_stack))
 130                 goto badframe;
 131
 132         return regs->a0;
 133
 134 badframe:
 135         task = current;
 136         if (show_unhandled_signals) {
 137                 pr_info_ratelimited(
 138                         "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
 139                         task->comm, task_pid_nr(task), __func__,
 140                         frame, (void *)regs->sepc, (void *)regs->sp);
 141         }
 142         force_sig(SIGSEGV, task);
 143         return 0;
 144 }
 145
 146 static long setup_sigcontext(struct rt_sigframe __user *frame,
 147         struct pt_regs *regs)
 148 {
 149         struct sigcontext __user *sc = &frame->uc.uc_mcontext;
 150         long err;
 151         /* sc_regs is structured the same as the start of pt_regs */
 152         err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
 153         /* Save the floating-point state. */
 154         if (has_fpu)
 155                 err |= save_fp_state(regs, &sc->sc_fpregs);
 156         return err;
 157 }
 158
 159 static inline void __user *get_sigframe(struct ksignal *ksig,
 160         struct pt_regs *regs, size_t framesize)
 161 {
 162         unsigned long sp;
 163         /* Default to using normal stack */
 164         sp = regs->sp;
 165
 166         /*
 167          * If we are on the alternate signal stack and would overflow it, don't.
 168          * Return an always-bogus address instead so we will die with SIGSEGV.
 169          */
 170         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 171                 return (void __user __force *)(-1UL);
 172
 173         /* This is the X/Open sanctioned signal stack switching. */
 174         sp = sigsp(sp, ksig) - framesize;
 175
 176         /* Align the stack frame. */
 177         sp &= ~0xfUL;
 178
 179         return (void __user *)sp;
 180 }
 181
 182
 183 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 184         struct pt_regs *regs)
 185 {
 186         struct rt_sigframe __user *frame;
 187         long err = 0;
 188
 189         frame = get_sigframe(ksig, regs, sizeof(*frame));
 190         if (!access_ok(frame, sizeof(*frame)))
 191                 return -EFAULT;
 192
 193         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 194
 195         /* Create the ucontext. */
 196         err |= __put_user(0, &frame->uc.uc_flags);
 197         err |= __put_user(NULL, &frame->uc.uc_link);
 198         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 199         err |= setup_sigcontext(frame, regs);
 200         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 201         if (err)
 202                 return -EFAULT;
 203
 204         /* Set up to return from userspace. */
 205         regs->ra = (unsigned long)VDSO_SYMBOL(
 206                 current->mm->context.vdso, rt_sigreturn);
 207
 208         /*
 209          * Set up registers for signal handler.
 210          * Registers that we don't modify keep the value they had from
 211          * user-space at the time we took the signal.
 212          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 213          * since some things rely on this (e.g. glibc's debug/segfault.c).
 214          */
 215         regs->sepc = (unsigned long)ksig->ka.sa.sa_handler;
 216         regs->sp = (unsigned long)frame;
 217         regs->a0 = ksig->sig;                     /* a0: signal number */
 218         regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
 219         regs->a2 = (unsigned long)(&frame->uc);   /* a2: ucontext pointer */
 220
 221 #if DEBUG_SIG
 222         pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
 223                 current->comm, task_pid_nr(current), ksig->sig,
 224                 (void *)regs->sepc, (void *)regs->ra, frame);
 225 #endif
 226
 227         return 0;
 228 }
 229
 230 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 231 {
 232         sigset_t *oldset = sigmask_to_save();
 233         int ret;
 234
 235         /* Are we from a system call? */
 236         if (regs->scause == EXC_SYSCALL) {
 237                 /* Avoid additional syscall restarting via ret_from_exception */
 238                 regs->scause = -1UL;
 239
 240                 /* If so, check system call restarting.. */
 241                 switch (regs->a0) {
 242                 case -ERESTART_RESTARTBLOCK:
 243                 case -ERESTARTNOHAND:
 244                         regs->a0 = -EINTR;
 245                         break;
 246
 247                 case -ERESTARTSYS:
 248                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 249                                 regs->a0 = -EINTR;
 250                                 break;
 251                         }
 252                         /* fallthrough */
 253                 case -ERESTARTNOINTR:
 254                         regs->a0 = regs->orig_a0;
 255                         regs->sepc -= 0x4;
 256                         break;
 257                 }
 258         }
 259
 260         /* Set up the stack frame */
 261         ret = setup_rt_frame(ksig, oldset, regs);
 262
 263         signal_setup_done(ret, ksig, 0);
 264 }
 265
 266 static void do_signal(struct pt_regs *regs)
 267 {
 268         struct ksignal ksig;
 269
 270         if (get_signal(&ksig)) {
 271                 /* Actually deliver the signal */
 272                 handle_signal(&ksig, regs);
 273                 return;
 274         }
 275
 276         /* Did we come from a system call? */
 277         if (regs->scause == EXC_SYSCALL) {
 278                 /* Avoid additional syscall restarting via ret_from_exception */
 279                 regs->scause = -1UL;
 280
 281                 /* Restart the system call - no handlers present */
 282                 switch (regs->a0) {
 283                 case -ERESTARTNOHAND:
 284                 case -ERESTARTSYS:
 285                 case -ERESTARTNOINTR:
 286                         regs->a0 = regs->orig_a0;
 287                         regs->sepc -= 0x4;
 288                         break;
 289                 case -ERESTART_RESTARTBLOCK:
 290                         regs->a0 = regs->orig_a0;
 291                         regs->a7 = __NR_restart_syscall;
 292                         regs->sepc -= 0x4;
 293                         break;
 294                 }
 295         }
 296
 297         /*
 298          * If there is no signal to deliver, we just put the saved
 299          * sigmask back.
 300          */
 301         restore_saved_sigmask();
 302 }
 303
 304 /*
 305  * notification of userspace execution resumption
 306  * - triggered by the _TIF_WORK_MASK flags
 307  */
 308 asmlinkage void do_notify_resume(struct pt_regs *regs,
 309         unsigned long thread_info_flags)
 310 {
 311         /* Handle pending signal delivery */
 312         if (thread_info_flags & _TIF_SIGPENDING)
 313                 do_signal(regs);
 314
 315         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 316                 clear_thread_flag(TIF_NOTIFY_RESUME);
 317                 tracehook_notify_resume(regs);
 318         }
 319 }