arch/nios2/kernel/signal.c

   1 /*
   2  * Copyright (C) 2013-2014 Altera Corporation
   3  * Copyright (C) 2011-2012 Tobias Klauser <tklauser@distanz.ch>
   4  * Copyright (C) 2004 Microtronix Datacom Ltd
   5  * Copyright (C) 1991, 1992 Linus Torvalds
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License.  See the file COPYING in the main directory of this archive
   9  * for more details.
  10  */
  11
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/unistd.h>
  17 #include <linux/personality.h>
  18 #include <linux/tracehook.h>
  19
  20 #include <asm/ucontext.h>
  21 #include <asm/cacheflush.h>
  22
  23 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  24
  25 /*
  26  * Do a signal return; undo the signal stack.
  27  *
  28  * Keep the return code on the stack quadword aligned!
  29  * That makes the cache flush below easier.
  30  */
  31
  32 struct rt_sigframe {
  33         struct siginfo info;
  34         struct ucontext uc;
  35 };
  36
  37 static inline int rt_restore_ucontext(struct pt_regs *regs,
  38                                         struct switch_stack *sw,
  39                                         struct ucontext *uc, int *pr2)
  40 {
  41         int temp;
  42         unsigned long *gregs = uc->uc_mcontext.gregs;
  43         int err;
  44
  45         /* Always make any pending restarted system calls return -EINTR */
  46         current->restart_block.fn = do_no_restart_syscall;
  47
  48         err = __get_user(temp, &uc->uc_mcontext.version);
  49         if (temp != MCONTEXT_VERSION)
  50                 goto badframe;
  51         /* restore passed registers */
  52         err |= __get_user(regs->r1, &gregs[0]);
  53         err |= __get_user(regs->r2, &gregs[1]);
  54         err |= __get_user(regs->r3, &gregs[2]);
  55         err |= __get_user(regs->r4, &gregs[3]);
  56         err |= __get_user(regs->r5, &gregs[4]);
  57         err |= __get_user(regs->r6, &gregs[5]);
  58         err |= __get_user(regs->r7, &gregs[6]);
  59         err |= __get_user(regs->r8, &gregs[7]);
  60         err |= __get_user(regs->r9, &gregs[8]);
  61         err |= __get_user(regs->r10, &gregs[9]);
  62         err |= __get_user(regs->r11, &gregs[10]);
  63         err |= __get_user(regs->r12, &gregs[11]);
  64         err |= __get_user(regs->r13, &gregs[12]);
  65         err |= __get_user(regs->r14, &gregs[13]);
  66         err |= __get_user(regs->r15, &gregs[14]);
  67         err |= __get_user(sw->r16, &gregs[15]);
  68         err |= __get_user(sw->r17, &gregs[16]);
  69         err |= __get_user(sw->r18, &gregs[17]);
  70         err |= __get_user(sw->r19, &gregs[18]);
  71         err |= __get_user(sw->r20, &gregs[19]);
  72         err |= __get_user(sw->r21, &gregs[20]);
  73         err |= __get_user(sw->r22, &gregs[21]);
  74         err |= __get_user(sw->r23, &gregs[22]);
  75         /* gregs[23] is handled below */
  76         err |= __get_user(sw->fp, &gregs[24]);  /* Verify, should this be
  77                                                         settable */
  78         err |= __get_user(sw->gp, &gregs[25]);  /* Verify, should this be
  79                                                         settable */
  80
  81         err |= __get_user(temp, &gregs[26]);  /* Not really necessary no user
  82                                                         settable bits */
  83         err |= __get_user(regs->ea, &gregs[27]);
  84
  85         err |= __get_user(regs->ra, &gregs[23]);
  86         err |= __get_user(regs->sp, &gregs[28]);
  87
  88         regs->orig_r2 = -1;             /* disable syscall checks */
  89
  90         err |= restore_altstack(&uc->uc_stack);
  91         if (err)
  92                 goto badframe;
  93
  94         *pr2 = regs->r2;
  95         return err;
  96
  97 badframe:
  98         return 1;
  99 }
 100
 101 asmlinkage int do_rt_sigreturn(struct switch_stack *sw)
 102 {
 103         struct pt_regs *regs = (struct pt_regs *)(sw + 1);
 104         /* Verify, can we follow the stack back */
 105         struct rt_sigframe *frame = (struct rt_sigframe *) regs->sp;
 106         sigset_t set;
 107         int rval;
 108
 109         if (!access_ok(frame, sizeof(*frame)))
 110                 goto badframe;
 111
 112         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 113                 goto badframe;
 114
 115         set_current_blocked(&set);
 116
 117         if (rt_restore_ucontext(regs, sw, &frame->uc, &rval))
 118                 goto badframe;
 119
 120         return rval;
 121
 122 badframe:
 123         force_sig(SIGSEGV);
 124         return 0;
 125 }
 126
 127 static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
 128 {
 129         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 130         unsigned long *gregs = uc->uc_mcontext.gregs;
 131         int err = 0;
 132
 133         err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
 134         err |= __put_user(regs->r1, &gregs[0]);
 135         err |= __put_user(regs->r2, &gregs[1]);
 136         err |= __put_user(regs->r3, &gregs[2]);
 137         err |= __put_user(regs->r4, &gregs[3]);
 138         err |= __put_user(regs->r5, &gregs[4]);
 139         err |= __put_user(regs->r6, &gregs[5]);
 140         err |= __put_user(regs->r7, &gregs[6]);
 141         err |= __put_user(regs->r8, &gregs[7]);
 142         err |= __put_user(regs->r9, &gregs[8]);
 143         err |= __put_user(regs->r10, &gregs[9]);
 144         err |= __put_user(regs->r11, &gregs[10]);
 145         err |= __put_user(regs->r12, &gregs[11]);
 146         err |= __put_user(regs->r13, &gregs[12]);
 147         err |= __put_user(regs->r14, &gregs[13]);
 148         err |= __put_user(regs->r15, &gregs[14]);
 149         err |= __put_user(sw->r16, &gregs[15]);
 150         err |= __put_user(sw->r17, &gregs[16]);
 151         err |= __put_user(sw->r18, &gregs[17]);
 152         err |= __put_user(sw->r19, &gregs[18]);
 153         err |= __put_user(sw->r20, &gregs[19]);
 154         err |= __put_user(sw->r21, &gregs[20]);
 155         err |= __put_user(sw->r22, &gregs[21]);
 156         err |= __put_user(sw->r23, &gregs[22]);
 157         err |= __put_user(regs->ra, &gregs[23]);
 158         err |= __put_user(sw->fp, &gregs[24]);
 159         err |= __put_user(sw->gp, &gregs[25]);
 160         err |= __put_user(regs->ea, &gregs[27]);
 161         err |= __put_user(regs->sp, &gregs[28]);
 162         return err;
 163 }
 164
 165 static inline void *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 166                                  size_t frame_size)
 167 {
 168         unsigned long usp;
 169
 170         /* Default to using normal stack.  */
 171         usp = regs->sp;
 172
 173         /* This is the X/Open sanctioned signal stack switching.  */
 174         usp = sigsp(usp, ksig);
 175
 176         /* Verify, is it 32 or 64 bit aligned */
 177         return (void *)((usp - frame_size) & -8UL);
 178 }
 179
 180 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 181                           struct pt_regs *regs)
 182 {
 183         struct rt_sigframe *frame;
 184         int err = 0;
 185
 186         frame = get_sigframe(ksig, regs, sizeof(*frame));
 187
 188         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 189                 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 190
 191         /* Create the ucontext.  */
 192         err |= __put_user(0, &frame->uc.uc_flags);
 193         err |= __put_user(0, &frame->uc.uc_link);
 194         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 195         err |= rt_setup_ucontext(&frame->uc, regs);
 196         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 197
 198         if (err)
 199                 goto give_sigsegv;
 200
 201         /* Set up to return from userspace; jump to fixed address sigreturn
 202            trampoline on kuser page.  */
 203         regs->ra = (unsigned long) (0x1044);
 204
 205         /* Set up registers for signal handler */
 206         regs->sp = (unsigned long) frame;
 207         regs->r4 = (unsigned long) ksig->sig;
 208         regs->r5 = (unsigned long) &frame->info;
 209         regs->r6 = (unsigned long) &frame->uc;
 210         regs->ea = (unsigned long) ksig->ka.sa.sa_handler;
 211         return 0;
 212
 213 give_sigsegv:
 214         force_sigsegv(ksig->sig);
 215         return -EFAULT;
 216 }
 217
 218 /*
 219  * OK, we're invoking a handler
 220  */
 221 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 222 {
 223         int ret;
 224         sigset_t *oldset = sigmask_to_save();
 225
 226         /* set up the stack frame */
 227         ret = setup_rt_frame(ksig, oldset, regs);
 228
 229         signal_setup_done(ret, ksig, 0);
 230 }
 231
 232 static int do_signal(struct pt_regs *regs)
 233 {
 234         unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 235         int restart = 0;
 236         struct ksignal ksig;
 237
 238         current->thread.kregs = regs;
 239
 240         /*
 241          * If we were from a system call, check for system call restarting...
 242          */
 243         if (regs->orig_r2 >= 0) {
 244                 continue_addr = regs->ea;
 245                 restart_addr = continue_addr - 4;
 246                 retval = regs->r2;
 247
 248                 /*
 249                  * Prepare for system call restart. We do this here so that a
 250                  * debugger will see the already changed PC.
 251                  */
 252                 switch (retval) {
 253                 case ERESTART_RESTARTBLOCK:
 254                         restart = -2;
 255                         fallthrough;
 256                 case ERESTARTNOHAND:
 257                 case ERESTARTSYS:
 258                 case ERESTARTNOINTR:
 259                         restart++;
 260                         regs->r2 = regs->orig_r2;
 261                         regs->r7 = regs->orig_r7;
 262                         regs->ea = restart_addr;
 263                         break;
 264                 }
 265         }
 266
 267         if (get_signal(&ksig)) {
 268                 /* handler */
 269                 if (unlikely(restart && regs->ea == restart_addr)) {
 270                         if (retval == ERESTARTNOHAND ||
 271                             retval == ERESTART_RESTARTBLOCK ||
 272                              (retval == ERESTARTSYS
 273                                 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
 274                                 regs->r2 = EINTR;
 275                                 regs->r7 = 1;
 276                                 regs->ea = continue_addr;
 277                         }
 278                 }
 279                 handle_signal(&ksig, regs);
 280                 return 0;
 281         }
 282
 283         /*
 284          * No handler present
 285          */
 286         if (unlikely(restart) && regs->ea == restart_addr) {
 287                 regs->ea = continue_addr;
 288                 regs->r2 = __NR_restart_syscall;
 289         }
 290
 291         /*
 292         * If there's no signal to deliver, we just put the saved sigmask back.
 293         */
 294         restore_saved_sigmask();
 295
 296         return restart;
 297 }
 298
 299 asmlinkage int do_notify_resume(struct pt_regs *regs)
 300 {
 301         /*
 302          * We want the common case to go fast, which is why we may in certain
 303          * cases get here from kernel mode. Just return without doing anything
 304          * if so.
 305          */
 306         if (!user_mode(regs))
 307                 return 0;
 308
 309         if (test_thread_flag(TIF_SIGPENDING) ||
 310             test_thread_flag(TIF_NOTIFY_SIGNAL)) {
 311                 int restart = do_signal(regs);
 312
 313                 if (unlikely(restart)) {
 314                         /*
 315                          * Restart without handlers.
 316                          * Deal with it without leaving
 317                          * the kernel space.
 318                          */
 319                         return restart;
 320                 }
 321         } else if (test_thread_flag(TIF_NOTIFY_RESUME))
 322                 tracehook_notify_resume(regs);
 323
 324         return 0;
 325 }