linux/arch/nios2/kernel/signal.c
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   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
  32struct rt_sigframe {
  33        struct siginfo info;
  34        struct ucontext uc;
  35};
  36
  37static 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
  97badframe:
  98        return 1;
  99}
 100
 101asmlinkage 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
 122badframe:
 123        force_sig(SIGSEGV);
 124        return 0;
 125}
 126
 127static 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
 165static 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
 180static 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
 213give_sigsegv:
 214        force_sigsegv(ksig->sig);
 215        return -EFAULT;
 216}
 217
 218/*
 219 * OK, we're invoking a handler
 220 */
 221static 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
 232static 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                case ERESTARTNOHAND:
 256                case ERESTARTSYS:
 257                case ERESTARTNOINTR:
 258                        restart++;
 259                        regs->r2 = regs->orig_r2;
 260                        regs->r7 = regs->orig_r7;
 261                        regs->ea = restart_addr;
 262                        break;
 263                }
 264        }
 265
 266        if (get_signal(&ksig)) {
 267                /* handler */
 268                if (unlikely(restart && regs->ea == restart_addr)) {
 269                        if (retval == ERESTARTNOHAND ||
 270                            retval == ERESTART_RESTARTBLOCK ||
 271                             (retval == ERESTARTSYS
 272                                && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
 273                                regs->r2 = EINTR;
 274                                regs->r7 = 1;
 275                                regs->ea = continue_addr;
 276                        }
 277                }
 278                handle_signal(&ksig, regs);
 279                return 0;
 280        }
 281
 282        /*
 283         * No handler present
 284         */
 285        if (unlikely(restart) && regs->ea == restart_addr) {
 286                regs->ea = continue_addr;
 287                regs->r2 = __NR_restart_syscall;
 288        }
 289
 290        /*
 291        * If there's no signal to deliver, we just put the saved sigmask back.
 292        */
 293        restore_saved_sigmask();
 294
 295        return restart;
 296}
 297
 298asmlinkage int do_notify_resume(struct pt_regs *regs)
 299{
 300        /*
 301         * We want the common case to go fast, which is why we may in certain
 302         * cases get here from kernel mode. Just return without doing anything
 303         * if so.
 304         */
 305        if (!user_mode(regs))
 306                return 0;
 307
 308        if (test_thread_flag(TIF_SIGPENDING)) {
 309                int restart = do_signal(regs);
 310
 311                if (unlikely(restart)) {
 312                        /*
 313                         * Restart without handlers.
 314                         * Deal with it without leaving
 315                         * the kernel space.
 316                         */
 317                        return restart;
 318                }
 319        } else if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 320                tracehook_notify_resume(regs);
 321
 322        return 0;
 323}
 324