arch/sparc/kernel/signal_32.c

   1 /*  linux/arch/sparc/kernel/signal.c
   2  *
   3  *  Copyright (C) 1991, 1992  Linus Torvalds
   4  *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
   6  *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
   7  */
   8
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/signal.h>
  12 #include <linux/errno.h>
  13 #include <linux/wait.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/unistd.h>
  16 #include <linux/mm.h>
  17 #include <linux/tty.h>
  18 #include <linux/smp.h>
  19 #include <linux/binfmts.h>      /* do_coredum */
  20 #include <linux/bitops.h>
  21 #include <linux/tracehook.h>
  22
  23 #include <asm/uaccess.h>
  24 #include <asm/ptrace.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/cacheflush.h>     /* flush_sig_insns */
  28 #include <asm/switch_to.h>
  29
  30 #include "sigutil.h"
  31 #include "kernel.h"
  32
  33 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
  34                    void *fpqueue, unsigned long *fpqdepth);
  35 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
  36
  37 struct signal_frame {
  38         struct sparc_stackf     ss;
  39         __siginfo32_t           info;
  40         __siginfo_fpu_t __user  *fpu_save;
  41         unsigned long           insns[2] __attribute__ ((aligned (8)));
  42         unsigned int            extramask[_NSIG_WORDS - 1];
  43         unsigned int            extra_size; /* Should be 0 */
  44         __siginfo_rwin_t __user *rwin_save;
  45 } __attribute__((aligned(8)));
  46
  47 struct rt_signal_frame {
  48         struct sparc_stackf     ss;
  49         siginfo_t               info;
  50         struct pt_regs          regs;
  51         sigset_t                mask;
  52         __siginfo_fpu_t __user  *fpu_save;
  53         unsigned int            insns[2];
  54         stack_t                 stack;
  55         unsigned int            extra_size; /* Should be 0 */
  56         __siginfo_rwin_t __user *rwin_save;
  57 } __attribute__((aligned(8)));
  58
  59 /* Align macros */
  60 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
  61 #define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))
  62
  63 asmlinkage void do_sigreturn(struct pt_regs *regs)
  64 {
  65         struct signal_frame __user *sf;
  66         unsigned long up_psr, pc, npc;
  67         sigset_t set;
  68         __siginfo_fpu_t __user *fpu_save;
  69         __siginfo_rwin_t __user *rwin_save;
  70         int err;
  71
  72         /* Always make any pending restarted system calls return -EINTR */
  73         current->restart_block.fn = do_no_restart_syscall;
  74
  75         synchronize_user_stack();
  76
  77         sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
  78
  79         /* 1. Make sure we are not getting garbage from the user */
  80         if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
  81                 goto segv_and_exit;
  82
  83         if (((unsigned long) sf) & 3)
  84                 goto segv_and_exit;
  85
  86         err = __get_user(pc,  &sf->info.si_regs.pc);
  87         err |= __get_user(npc, &sf->info.si_regs.npc);
  88
  89         if ((pc | npc) & 3)
  90                 goto segv_and_exit;
  91
  92         /* 2. Restore the state */
  93         up_psr = regs->psr;
  94         err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
  95
  96         /* User can only change condition codes and FPU enabling in %psr. */
  97         regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
  98                   | (regs->psr & (PSR_ICC | PSR_EF));
  99
 100         /* Prevent syscall restart.  */
 101         pt_regs_clear_syscall(regs);
 102
 103         err |= __get_user(fpu_save, &sf->fpu_save);
 104         if (fpu_save)
 105                 err |= restore_fpu_state(regs, fpu_save);
 106         err |= __get_user(rwin_save, &sf->rwin_save);
 107         if (rwin_save)
 108                 err |= restore_rwin_state(rwin_save);
 109
 110         /* This is pretty much atomic, no amount locking would prevent
 111          * the races which exist anyways.
 112          */
 113         err |= __get_user(set.sig[0], &sf->info.si_mask);
 114         err |= __copy_from_user(&set.sig[1], &sf->extramask,
 115                                 (_NSIG_WORDS-1) * sizeof(unsigned int));
 116
 117         if (err)
 118                 goto segv_and_exit;
 119
 120         set_current_blocked(&set);
 121         return;
 122
 123 segv_and_exit:
 124         force_sig(SIGSEGV, current);
 125 }
 126
 127 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 128 {
 129         struct rt_signal_frame __user *sf;
 130         unsigned int psr, pc, npc;
 131         __siginfo_fpu_t __user *fpu_save;
 132         __siginfo_rwin_t __user *rwin_save;
 133         sigset_t set;
 134         int err;
 135
 136         synchronize_user_stack();
 137         sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
 138         if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
 139             (((unsigned long) sf) & 0x03))
 140                 goto segv;
 141
 142         err = __get_user(pc, &sf->regs.pc);
 143         err |= __get_user(npc, &sf->regs.npc);
 144         err |= ((pc | npc) & 0x03);
 145
 146         err |= __get_user(regs->y, &sf->regs.y);
 147         err |= __get_user(psr, &sf->regs.psr);
 148
 149         err |= __copy_from_user(&regs->u_regs[UREG_G1],
 150                                 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
 151
 152         regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
 153
 154         /* Prevent syscall restart.  */
 155         pt_regs_clear_syscall(regs);
 156
 157         err |= __get_user(fpu_save, &sf->fpu_save);
 158         if (!err && fpu_save)
 159                 err |= restore_fpu_state(regs, fpu_save);
 160         err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 161         err |= restore_altstack(&sf->stack);
 162
 163         if (err)
 164                 goto segv;
 165
 166         regs->pc = pc;
 167         regs->npc = npc;
 168
 169         err |= __get_user(rwin_save, &sf->rwin_save);
 170         if (!err && rwin_save) {
 171                 if (restore_rwin_state(rwin_save))
 172                         goto segv;
 173         }
 174
 175         set_current_blocked(&set);
 176         return;
 177 segv:
 178         force_sig(SIGSEGV, current);
 179 }
 180
 181 /* Checks if the fp is valid */
 182 static inline int invalid_frame_pointer(void __user *fp, int fplen)
 183 {
 184         if ((((unsigned long) fp) & 7) || !__access_ok((unsigned long)fp, fplen))
 185                 return 1;
 186
 187         return 0;
 188 }
 189
 190 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
 191 {
 192         unsigned long sp = regs->u_regs[UREG_FP];
 193
 194         /*
 195          * If we are on the alternate signal stack and would overflow it, don't.
 196          * Return an always-bogus address instead so we will die with SIGSEGV.
 197          */
 198         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 199                 return (void __user *) -1L;
 200
 201         /* This is the X/Open sanctioned signal stack switching.  */
 202         sp = sigsp(sp, ksig) - framesize;
 203
 204         /* Always align the stack frame.  This handles two cases.  First,
 205          * sigaltstack need not be mindful of platform specific stack
 206          * alignment.  Second, if we took this signal because the stack
 207          * is not aligned properly, we'd like to take the signal cleanly
 208          * and report that.
 209          */
 210         sp &= ~15UL;
 211
 212         return (void __user *) sp;
 213 }
 214
 215 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
 216                        sigset_t *oldset)
 217 {
 218         struct signal_frame __user *sf;
 219         int sigframe_size, err, wsaved;
 220         void __user *tail;
 221
 222         /* 1. Make sure everything is clean */
 223         synchronize_user_stack();
 224
 225         wsaved = current_thread_info()->w_saved;
 226
 227         sigframe_size = sizeof(*sf);
 228         if (used_math())
 229                 sigframe_size += sizeof(__siginfo_fpu_t);
 230         if (wsaved)
 231                 sigframe_size += sizeof(__siginfo_rwin_t);
 232
 233         sf = (struct signal_frame __user *)
 234                 get_sigframe(ksig, regs, sigframe_size);
 235
 236         if (invalid_frame_pointer(sf, sigframe_size)) {
 237                 do_exit(SIGILL);
 238                 return -EINVAL;
 239         }
 240
 241         tail = sf + 1;
 242
 243         /* 2. Save the current process state */
 244         err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
 245
 246         err |= __put_user(0, &sf->extra_size);
 247
 248         if (used_math()) {
 249                 __siginfo_fpu_t __user *fp = tail;
 250                 tail += sizeof(*fp);
 251                 err |= save_fpu_state(regs, fp);
 252                 err |= __put_user(fp, &sf->fpu_save);
 253         } else {
 254                 err |= __put_user(0, &sf->fpu_save);
 255         }
 256         if (wsaved) {
 257                 __siginfo_rwin_t __user *rwp = tail;
 258                 tail += sizeof(*rwp);
 259                 err |= save_rwin_state(wsaved, rwp);
 260                 err |= __put_user(rwp, &sf->rwin_save);
 261         } else {
 262                 err |= __put_user(0, &sf->rwin_save);
 263         }
 264
 265         err |= __put_user(oldset->sig[0], &sf->info.si_mask);
 266         err |= __copy_to_user(sf->extramask, &oldset->sig[1],
 267                               (_NSIG_WORDS - 1) * sizeof(unsigned int));
 268         if (!wsaved) {
 269                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 270                                       sizeof(struct reg_window32));
 271         } else {
 272                 struct reg_window32 *rp;
 273
 274                 rp = &current_thread_info()->reg_window[wsaved - 1];
 275                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 276         }
 277         if (err)
 278                 return err;
 279
 280         /* 3. signal handler back-trampoline and parameters */
 281         regs->u_regs[UREG_FP] = (unsigned long) sf;
 282         regs->u_regs[UREG_I0] = ksig->sig;
 283         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 284         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
 285
 286         /* 4. signal handler */
 287         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 288         regs->npc = (regs->pc + 4);
 289
 290         /* 5. return to kernel instructions */
 291         if (ksig->ka.ka_restorer)
 292                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 293         else {
 294                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 295
 296                 /* mov __NR_sigreturn, %g1 */
 297                 err |= __put_user(0x821020d8, &sf->insns[0]);
 298
 299                 /* t 0x10 */
 300                 err |= __put_user(0x91d02010, &sf->insns[1]);
 301                 if (err)
 302                         return err;
 303
 304                 /* Flush instruction space. */
 305                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 306         }
 307         return 0;
 308 }
 309
 310 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
 311                           sigset_t *oldset)
 312 {
 313         struct rt_signal_frame __user *sf;
 314         int sigframe_size, wsaved;
 315         void __user *tail;
 316         unsigned int psr;
 317         int err;
 318
 319         synchronize_user_stack();
 320         wsaved = current_thread_info()->w_saved;
 321         sigframe_size = sizeof(*sf);
 322         if (used_math())
 323                 sigframe_size += sizeof(__siginfo_fpu_t);
 324         if (wsaved)
 325                 sigframe_size += sizeof(__siginfo_rwin_t);
 326         sf = (struct rt_signal_frame __user *)
 327                 get_sigframe(ksig, regs, sigframe_size);
 328         if (invalid_frame_pointer(sf, sigframe_size)) {
 329                 do_exit(SIGILL);
 330                 return -EINVAL;
 331         }
 332
 333         tail = sf + 1;
 334         err  = __put_user(regs->pc, &sf->regs.pc);
 335         err |= __put_user(regs->npc, &sf->regs.npc);
 336         err |= __put_user(regs->y, &sf->regs.y);
 337         psr = regs->psr;
 338         if (used_math())
 339                 psr |= PSR_EF;
 340         err |= __put_user(psr, &sf->regs.psr);
 341         err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
 342         err |= __put_user(0, &sf->extra_size);
 343
 344         if (psr & PSR_EF) {
 345                 __siginfo_fpu_t __user *fp = tail;
 346                 tail += sizeof(*fp);
 347                 err |= save_fpu_state(regs, fp);
 348                 err |= __put_user(fp, &sf->fpu_save);
 349         } else {
 350                 err |= __put_user(0, &sf->fpu_save);
 351         }
 352         if (wsaved) {
 353                 __siginfo_rwin_t __user *rwp = tail;
 354                 tail += sizeof(*rwp);
 355                 err |= save_rwin_state(wsaved, rwp);
 356                 err |= __put_user(rwp, &sf->rwin_save);
 357         } else {
 358                 err |= __put_user(0, &sf->rwin_save);
 359         }
 360         err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
 361
 362         /* Setup sigaltstack */
 363         err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
 364
 365         if (!wsaved) {
 366                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 367                                       sizeof(struct reg_window32));
 368         } else {
 369                 struct reg_window32 *rp;
 370
 371                 rp = &current_thread_info()->reg_window[wsaved - 1];
 372                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 373         }
 374
 375         err |= copy_siginfo_to_user(&sf->info, &ksig->info);
 376
 377         if (err)
 378                 return err;
 379
 380         regs->u_regs[UREG_FP] = (unsigned long) sf;
 381         regs->u_regs[UREG_I0] = ksig->sig;
 382         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 383         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
 384
 385         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 386         regs->npc = (regs->pc + 4);
 387
 388         if (ksig->ka.ka_restorer)
 389                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 390         else {
 391                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 392
 393                 /* mov __NR_sigreturn, %g1 */
 394                 err |= __put_user(0x821020d8, &sf->insns[0]);
 395
 396                 /* t 0x10 */
 397                 err |= __put_user(0x91d02010, &sf->insns[1]);
 398                 if (err)
 399                         return err;
 400
 401                 /* Flush instruction space. */
 402                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 403         }
 404         return 0;
 405 }
 406
 407 static inline void
 408 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 409 {
 410         sigset_t *oldset = sigmask_to_save();
 411         int err;
 412
 413         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 414                 err = setup_rt_frame(ksig, regs, oldset);
 415         else
 416                 err = setup_frame(ksig, regs, oldset);
 417         signal_setup_done(err, ksig, 0);
 418 }
 419
 420 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 421                                    struct sigaction *sa)
 422 {
 423         switch(regs->u_regs[UREG_I0]) {
 424         case ERESTART_RESTARTBLOCK:
 425         case ERESTARTNOHAND:
 426         no_system_call_restart:
 427                 regs->u_regs[UREG_I0] = EINTR;
 428                 regs->psr |= PSR_C;
 429                 break;
 430         case ERESTARTSYS:
 431                 if (!(sa->sa_flags & SA_RESTART))
 432                         goto no_system_call_restart;
 433                 /* fallthrough */
 434         case ERESTARTNOINTR:
 435                 regs->u_regs[UREG_I0] = orig_i0;
 436                 regs->pc -= 4;
 437                 regs->npc -= 4;
 438         }
 439 }
 440
 441 /* Note that 'init' is a special process: it doesn't get signals it doesn't
 442  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 443  * mistake.
 444  */
 445 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 446 {
 447         struct ksignal ksig;
 448         int restart_syscall;
 449         bool has_handler;
 450
 451         /* It's a lot of work and synchronization to add a new ptrace
 452          * register for GDB to save and restore in order to get
 453          * orig_i0 correct for syscall restarts when debugging.
 454          *
 455          * Although it should be the case that most of the global
 456          * registers are volatile across a system call, glibc already
 457          * depends upon that fact that we preserve them.  So we can't
 458          * just use any global register to save away the orig_i0 value.
 459          *
 460          * In particular %g2, %g3, %g4, and %g5 are all assumed to be
 461          * preserved across a system call trap by various pieces of
 462          * code in glibc.
 463          *
 464          * %g7 is used as the "thread register".   %g6 is not used in
 465          * any fixed manner.  %g6 is used as a scratch register and
 466          * a compiler temporary, but it's value is never used across
 467          * a system call.  Therefore %g6 is usable for orig_i0 storage.
 468          */
 469         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
 470                 regs->u_regs[UREG_G6] = orig_i0;
 471
 472         has_handler = get_signal(&ksig);
 473
 474         /* If the debugger messes with the program counter, it clears
 475          * the software "in syscall" bit, directing us to not perform
 476          * a syscall restart.
 477          */
 478         restart_syscall = 0;
 479         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
 480                 restart_syscall = 1;
 481                 orig_i0 = regs->u_regs[UREG_G6];
 482         }
 483
 484         if (has_handler) {
 485                 if (restart_syscall)
 486                         syscall_restart(orig_i0, regs, &ksig.ka.sa);
 487                 handle_signal(&ksig, regs);
 488         } else {
 489                 if (restart_syscall) {
 490                         switch (regs->u_regs[UREG_I0]) {
 491                         case ERESTARTNOHAND:
 492                         case ERESTARTSYS:
 493                         case ERESTARTNOINTR:
 494                                 /* replay the system call when we are done */
 495                                 regs->u_regs[UREG_I0] = orig_i0;
 496                                 regs->pc -= 4;
 497                                 regs->npc -= 4;
 498                                 pt_regs_clear_syscall(regs);
 499                         case ERESTART_RESTARTBLOCK:
 500                                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
 501                                 regs->pc -= 4;
 502                                 regs->npc -= 4;
 503                                 pt_regs_clear_syscall(regs);
 504                         }
 505                 }
 506                 restore_saved_sigmask();
 507         }
 508 }
 509
 510 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
 511                       unsigned long thread_info_flags)
 512 {
 513         if (thread_info_flags & _TIF_SIGPENDING)
 514                 do_signal(regs, orig_i0);
 515         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 516                 clear_thread_flag(TIF_NOTIFY_RESUME);
 517                 tracehook_notify_resume(regs);
 518         }
 519 }
 520
 521 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr,
 522                                struct sigstack __user *ossptr,
 523                                unsigned long sp)
 524 {
 525         int ret = -EFAULT;
 526
 527         /* First see if old state is wanted. */
 528         if (ossptr) {
 529                 if (put_user(current->sas_ss_sp + current->sas_ss_size,
 530                              &ossptr->the_stack) ||
 531                     __put_user(on_sig_stack(sp), &ossptr->cur_status))
 532                         goto out;
 533         }
 534
 535         /* Now see if we want to update the new state. */
 536         if (ssptr) {
 537                 char *ss_sp;
 538
 539                 if (get_user(ss_sp, &ssptr->the_stack))
 540                         goto out;
 541                 /* If the current stack was set with sigaltstack, don't
 542                    swap stacks while we are on it.  */
 543                 ret = -EPERM;
 544                 if (current->sas_ss_sp && on_sig_stack(sp))
 545                         goto out;
 546
 547                 /* Since we don't know the extent of the stack, and we don't
 548                    track onstack-ness, but rather calculate it, we must
 549                    presume a size.  Ho hum this interface is lossy.  */
 550                 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
 551                 current->sas_ss_size = SIGSTKSZ;
 552         }
 553         ret = 0;
 554 out:
 555         return ret;
 556 }