arch/sparc/kernel/signal_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*  linux/arch/sparc/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   6  *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
   7  *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/wait.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/unistd.h>
  17 #include <linux/mm.h>
  18 #include <linux/tty.h>
  19 #include <linux/smp.h>
  20 #include <linux/binfmts.h>      /* do_coredum */
  21 #include <linux/bitops.h>
  22 #include <linux/resume_user_mode.h>
  23
  24 #include <linux/uaccess.h>
  25 #include <asm/ptrace.h>
  26 #include <asm/cacheflush.h>     /* flush_sig_insns */
  27 #include <asm/switch_to.h>
  28
  29 #include "sigutil.h"
  30 #include "kernel.h"
  31
  32 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
  33                    void *fpqueue, unsigned long *fpqdepth);
  34 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
  35
  36 struct signal_frame {
  37         struct sparc_stackf     ss;
  38         __siginfo32_t           info;
  39         __siginfo_fpu_t __user  *fpu_save;
  40         unsigned long           insns[2] __attribute__ ((aligned (8)));
  41         unsigned int            extramask[_NSIG_WORDS - 1];
  42         unsigned int            extra_size; /* Should be 0 */
  43         __siginfo_rwin_t __user *rwin_save;
  44 } __attribute__((aligned(8)));
  45
  46 struct rt_signal_frame {
  47         struct sparc_stackf     ss;
  48         siginfo_t               info;
  49         struct pt_regs          regs;
  50         sigset_t                mask;
  51         __siginfo_fpu_t __user  *fpu_save;
  52         unsigned int            insns[2];
  53         stack_t                 stack;
  54         unsigned int            extra_size; /* Should be 0 */
  55         __siginfo_rwin_t __user *rwin_save;
  56 } __attribute__((aligned(8)));
  57
  58 /* Align macros */
  59 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
  60 #define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))
  61
  62 /* Checks if the fp is valid.  We always build signal frames which are
  63  * 16-byte aligned, therefore we can always enforce that the restore
  64  * frame has that property as well.
  65  */
  66 static inline bool invalid_frame_pointer(void __user *fp, int fplen)
  67 {
  68         if ((((unsigned long) fp) & 15) || !access_ok(fp, fplen))
  69                 return true;
  70
  71         return false;
  72 }
  73
  74 asmlinkage void do_sigreturn(struct pt_regs *regs)
  75 {
  76         unsigned long up_psr, pc, npc, ufp;
  77         struct signal_frame __user *sf;
  78         sigset_t set;
  79         __siginfo_fpu_t __user *fpu_save;
  80         __siginfo_rwin_t __user *rwin_save;
  81         int err;
  82
  83         /* Always make any pending restarted system calls return -EINTR */
  84         current->restart_block.fn = do_no_restart_syscall;
  85
  86         synchronize_user_stack();
  87
  88         sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
  89
  90         /* 1. Make sure we are not getting garbage from the user */
  91         if (invalid_frame_pointer(sf, sizeof(*sf)))
  92                 goto segv_and_exit;
  93
  94         if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP]))
  95                 goto segv_and_exit;
  96
  97         if (ufp & 0x7)
  98                 goto segv_and_exit;
  99
 100         err = __get_user(pc,  &sf->info.si_regs.pc);
 101         err |= __get_user(npc, &sf->info.si_regs.npc);
 102
 103         if ((pc | npc) & 3)
 104                 goto segv_and_exit;
 105
 106         /* 2. Restore the state */
 107         up_psr = regs->psr;
 108         err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
 109
 110         /* User can only change condition codes and FPU enabling in %psr. */
 111         regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
 112                   | (regs->psr & (PSR_ICC | PSR_EF));
 113
 114         /* Prevent syscall restart.  */
 115         pt_regs_clear_syscall(regs);
 116
 117         err |= __get_user(fpu_save, &sf->fpu_save);
 118         if (fpu_save)
 119                 err |= restore_fpu_state(regs, fpu_save);
 120         err |= __get_user(rwin_save, &sf->rwin_save);
 121         if (rwin_save)
 122                 err |= restore_rwin_state(rwin_save);
 123
 124         /* This is pretty much atomic, no amount locking would prevent
 125          * the races which exist anyways.
 126          */
 127         err |= __get_user(set.sig[0], &sf->info.si_mask);
 128         err |= __copy_from_user(&set.sig[1], &sf->extramask,
 129                                 (_NSIG_WORDS-1) * sizeof(unsigned int));
 130
 131         if (err)
 132                 goto segv_and_exit;
 133
 134         set_current_blocked(&set);
 135         return;
 136
 137 segv_and_exit:
 138         force_sig(SIGSEGV);
 139 }
 140
 141 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 142 {
 143         struct rt_signal_frame __user *sf;
 144         unsigned int psr, pc, npc, ufp;
 145         __siginfo_fpu_t __user *fpu_save;
 146         __siginfo_rwin_t __user *rwin_save;
 147         sigset_t set;
 148         int err;
 149
 150         synchronize_user_stack();
 151         sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
 152         if (invalid_frame_pointer(sf, sizeof(*sf)))
 153                 goto segv;
 154
 155         if (get_user(ufp, &sf->regs.u_regs[UREG_FP]))
 156                 goto segv;
 157
 158         if (ufp & 0x7)
 159                 goto segv;
 160
 161         err = __get_user(pc, &sf->regs.pc);
 162         err |= __get_user(npc, &sf->regs.npc);
 163         err |= ((pc | npc) & 0x03);
 164
 165         err |= __get_user(regs->y, &sf->regs.y);
 166         err |= __get_user(psr, &sf->regs.psr);
 167
 168         err |= __copy_from_user(&regs->u_regs[UREG_G1],
 169                                 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
 170
 171         regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
 172
 173         /* Prevent syscall restart.  */
 174         pt_regs_clear_syscall(regs);
 175
 176         err |= __get_user(fpu_save, &sf->fpu_save);
 177         if (!err && fpu_save)
 178                 err |= restore_fpu_state(regs, fpu_save);
 179         err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 180         err |= restore_altstack(&sf->stack);
 181
 182         if (err)
 183                 goto segv;
 184
 185         regs->pc = pc;
 186         regs->npc = npc;
 187
 188         err |= __get_user(rwin_save, &sf->rwin_save);
 189         if (!err && rwin_save) {
 190                 if (restore_rwin_state(rwin_save))
 191                         goto segv;
 192         }
 193
 194         set_current_blocked(&set);
 195         return;
 196 segv:
 197         force_sig(SIGSEGV);
 198 }
 199
 200 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
 201 {
 202         unsigned long sp = regs->u_regs[UREG_FP];
 203
 204         /*
 205          * If we are on the alternate signal stack and would overflow it, don't.
 206          * Return an always-bogus address instead so we will die with SIGSEGV.
 207          */
 208         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 209                 return (void __user *) -1L;
 210
 211         /* This is the X/Open sanctioned signal stack switching.  */
 212         sp = sigsp(sp, ksig) - framesize;
 213
 214         /* Always align the stack frame.  This handles two cases.  First,
 215          * sigaltstack need not be mindful of platform specific stack
 216          * alignment.  Second, if we took this signal because the stack
 217          * is not aligned properly, we'd like to take the signal cleanly
 218          * and report that.
 219          */
 220         sp &= ~15UL;
 221
 222         return (void __user *) sp;
 223 }
 224
 225 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
 226                        sigset_t *oldset)
 227 {
 228         struct signal_frame __user *sf;
 229         int sigframe_size, err, wsaved;
 230         void __user *tail;
 231
 232         /* 1. Make sure everything is clean */
 233         synchronize_user_stack();
 234
 235         wsaved = current_thread_info()->w_saved;
 236
 237         sigframe_size = sizeof(*sf);
 238         if (used_math())
 239                 sigframe_size += sizeof(__siginfo_fpu_t);
 240         if (wsaved)
 241                 sigframe_size += sizeof(__siginfo_rwin_t);
 242
 243         sf = (struct signal_frame __user *)
 244                 get_sigframe(ksig, regs, sigframe_size);
 245
 246         if (invalid_frame_pointer(sf, sigframe_size)) {
 247                 force_exit_sig(SIGILL);
 248                 return -EINVAL;
 249         }
 250
 251         tail = sf + 1;
 252
 253         /* 2. Save the current process state */
 254         err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
 255
 256         err |= __put_user(0, &sf->extra_size);
 257
 258         if (used_math()) {
 259                 __siginfo_fpu_t __user *fp = tail;
 260                 tail += sizeof(*fp);
 261                 err |= save_fpu_state(regs, fp);
 262                 err |= __put_user(fp, &sf->fpu_save);
 263         } else {
 264                 err |= __put_user(0, &sf->fpu_save);
 265         }
 266         if (wsaved) {
 267                 __siginfo_rwin_t __user *rwp = tail;
 268                 tail += sizeof(*rwp);
 269                 err |= save_rwin_state(wsaved, rwp);
 270                 err |= __put_user(rwp, &sf->rwin_save);
 271         } else {
 272                 err |= __put_user(0, &sf->rwin_save);
 273         }
 274
 275         err |= __put_user(oldset->sig[0], &sf->info.si_mask);
 276         err |= __copy_to_user(sf->extramask, &oldset->sig[1],
 277                               (_NSIG_WORDS - 1) * sizeof(unsigned int));
 278         if (!wsaved) {
 279                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 280                                       sizeof(struct reg_window32));
 281         } else {
 282                 struct reg_window32 *rp;
 283
 284                 rp = &current_thread_info()->reg_window[wsaved - 1];
 285                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 286         }
 287         if (err)
 288                 return err;
 289
 290         /* 3. signal handler back-trampoline and parameters */
 291         regs->u_regs[UREG_FP] = (unsigned long) sf;
 292         regs->u_regs[UREG_I0] = ksig->sig;
 293         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 294         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
 295
 296         /* 4. signal handler */
 297         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 298         regs->npc = (regs->pc + 4);
 299
 300         /* 5. return to kernel instructions */
 301         if (ksig->ka.ka_restorer)
 302                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 303         else {
 304                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 305
 306                 /* mov __NR_sigreturn, %g1 */
 307                 err |= __put_user(0x821020d8, &sf->insns[0]);
 308
 309                 /* t 0x10 */
 310                 err |= __put_user(0x91d02010, &sf->insns[1]);
 311                 if (err)
 312                         return err;
 313
 314                 /* Flush instruction space. */
 315                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 316         }
 317         return 0;
 318 }
 319
 320 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
 321                           sigset_t *oldset)
 322 {
 323         struct rt_signal_frame __user *sf;
 324         int sigframe_size, wsaved;
 325         void __user *tail;
 326         unsigned int psr;
 327         int err;
 328
 329         synchronize_user_stack();
 330         wsaved = current_thread_info()->w_saved;
 331         sigframe_size = sizeof(*sf);
 332         if (used_math())
 333                 sigframe_size += sizeof(__siginfo_fpu_t);
 334         if (wsaved)
 335                 sigframe_size += sizeof(__siginfo_rwin_t);
 336         sf = (struct rt_signal_frame __user *)
 337                 get_sigframe(ksig, regs, sigframe_size);
 338         if (invalid_frame_pointer(sf, sigframe_size)) {
 339                 force_exit_sig(SIGILL);
 340                 return -EINVAL;
 341         }
 342
 343         tail = sf + 1;
 344         err  = __put_user(regs->pc, &sf->regs.pc);
 345         err |= __put_user(regs->npc, &sf->regs.npc);
 346         err |= __put_user(regs->y, &sf->regs.y);
 347         psr = regs->psr;
 348         if (used_math())
 349                 psr |= PSR_EF;
 350         err |= __put_user(psr, &sf->regs.psr);
 351         err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
 352         err |= __put_user(0, &sf->extra_size);
 353
 354         if (psr & PSR_EF) {
 355                 __siginfo_fpu_t __user *fp = tail;
 356                 tail += sizeof(*fp);
 357                 err |= save_fpu_state(regs, fp);
 358                 err |= __put_user(fp, &sf->fpu_save);
 359         } else {
 360                 err |= __put_user(0, &sf->fpu_save);
 361         }
 362         if (wsaved) {
 363                 __siginfo_rwin_t __user *rwp = tail;
 364                 tail += sizeof(*rwp);
 365                 err |= save_rwin_state(wsaved, rwp);
 366                 err |= __put_user(rwp, &sf->rwin_save);
 367         } else {
 368                 err |= __put_user(0, &sf->rwin_save);
 369         }
 370         err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
 371
 372         /* Setup sigaltstack */
 373         err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
 374
 375         if (!wsaved) {
 376                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 377                                       sizeof(struct reg_window32));
 378         } else {
 379                 struct reg_window32 *rp;
 380
 381                 rp = &current_thread_info()->reg_window[wsaved - 1];
 382                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 383         }
 384
 385         err |= copy_siginfo_to_user(&sf->info, &ksig->info);
 386
 387         if (err)
 388                 return err;
 389
 390         regs->u_regs[UREG_FP] = (unsigned long) sf;
 391         regs->u_regs[UREG_I0] = ksig->sig;
 392         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 393         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
 394
 395         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 396         regs->npc = (regs->pc + 4);
 397
 398         if (ksig->ka.ka_restorer)
 399                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 400         else {
 401                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 402
 403                 /* mov __NR_rt_sigreturn, %g1 */
 404                 err |= __put_user(0x82102065, &sf->insns[0]);
 405
 406                 /* t 0x10 */
 407                 err |= __put_user(0x91d02010, &sf->insns[1]);
 408                 if (err)
 409                         return err;
 410
 411                 /* Flush instruction space. */
 412                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 413         }
 414         return 0;
 415 }
 416
 417 static inline void
 418 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 419 {
 420         sigset_t *oldset = sigmask_to_save();
 421         int err;
 422
 423         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 424                 err = setup_rt_frame(ksig, regs, oldset);
 425         else
 426                 err = setup_frame(ksig, regs, oldset);
 427         signal_setup_done(err, ksig, 0);
 428 }
 429
 430 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 431                                    struct sigaction *sa)
 432 {
 433         switch(regs->u_regs[UREG_I0]) {
 434         case ERESTART_RESTARTBLOCK:
 435         case ERESTARTNOHAND:
 436         no_system_call_restart:
 437                 regs->u_regs[UREG_I0] = EINTR;
 438                 regs->psr |= PSR_C;
 439                 break;
 440         case ERESTARTSYS:
 441                 if (!(sa->sa_flags & SA_RESTART))
 442                         goto no_system_call_restart;
 443                 fallthrough;
 444         case ERESTARTNOINTR:
 445                 regs->u_regs[UREG_I0] = orig_i0;
 446                 regs->pc -= 4;
 447                 regs->npc -= 4;
 448         }
 449 }
 450
 451 /* Note that 'init' is a special process: it doesn't get signals it doesn't
 452  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 453  * mistake.
 454  */
 455 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 456 {
 457         struct ksignal ksig;
 458         int restart_syscall;
 459         bool has_handler;
 460
 461         /* It's a lot of work and synchronization to add a new ptrace
 462          * register for GDB to save and restore in order to get
 463          * orig_i0 correct for syscall restarts when debugging.
 464          *
 465          * Although it should be the case that most of the global
 466          * registers are volatile across a system call, glibc already
 467          * depends upon that fact that we preserve them.  So we can't
 468          * just use any global register to save away the orig_i0 value.
 469          *
 470          * In particular %g2, %g3, %g4, and %g5 are all assumed to be
 471          * preserved across a system call trap by various pieces of
 472          * code in glibc.
 473          *
 474          * %g7 is used as the "thread register".   %g6 is not used in
 475          * any fixed manner.  %g6 is used as a scratch register and
 476          * a compiler temporary, but its value is never used across
 477          * a system call.  Therefore %g6 is usable for orig_i0 storage.
 478          */
 479         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
 480                 regs->u_regs[UREG_G6] = orig_i0;
 481
 482         has_handler = get_signal(&ksig);
 483
 484         /* If the debugger messes with the program counter, it clears
 485          * the software "in syscall" bit, directing us to not perform
 486          * a syscall restart.
 487          */
 488         restart_syscall = 0;
 489         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
 490                 restart_syscall = 1;
 491                 orig_i0 = regs->u_regs[UREG_G6];
 492         }
 493
 494         if (has_handler) {
 495                 if (restart_syscall)
 496                         syscall_restart(orig_i0, regs, &ksig.ka.sa);
 497                 handle_signal(&ksig, regs);
 498         } else {
 499                 if (restart_syscall) {
 500                         switch (regs->u_regs[UREG_I0]) {
 501                         case ERESTARTNOHAND:
 502                         case ERESTARTSYS:
 503                         case ERESTARTNOINTR:
 504                                 /* replay the system call when we are done */
 505                                 regs->u_regs[UREG_I0] = orig_i0;
 506                                 regs->pc -= 4;
 507                                 regs->npc -= 4;
 508                                 pt_regs_clear_syscall(regs);
 509                                 fallthrough;
 510                         case ERESTART_RESTARTBLOCK:
 511                                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
 512                                 regs->pc -= 4;
 513                                 regs->npc -= 4;
 514                                 pt_regs_clear_syscall(regs);
 515                         }
 516                 }
 517                 restore_saved_sigmask();
 518         }
 519 }
 520
 521 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
 522                       unsigned long thread_info_flags)
 523 {
 524         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 525                 do_signal(regs, orig_i0);
 526         if (thread_info_flags & _TIF_NOTIFY_RESUME)
 527                 resume_user_mode_work(regs);
 528 }
 529
 530 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr,
 531                                struct sigstack __user *ossptr,
 532                                unsigned long sp)
 533 {
 534         int ret = -EFAULT;
 535
 536         /* First see if old state is wanted. */
 537         if (ossptr) {
 538                 if (put_user(current->sas_ss_sp + current->sas_ss_size,
 539                              &ossptr->the_stack) ||
 540                     __put_user(on_sig_stack(sp), &ossptr->cur_status))
 541                         goto out;
 542         }
 543
 544         /* Now see if we want to update the new state. */
 545         if (ssptr) {
 546                 char *ss_sp;
 547
 548                 if (get_user(ss_sp, &ssptr->the_stack))
 549                         goto out;
 550                 /* If the current stack was set with sigaltstack, don't
 551                    swap stacks while we are on it.  */
 552                 ret = -EPERM;
 553                 if (current->sas_ss_sp && on_sig_stack(sp))
 554                         goto out;
 555
 556                 /* Since we don't know the extent of the stack, and we don't
 557                    track onstack-ness, but rather calculate it, we must
 558                    presume a size.  Ho hum this interface is lossy.  */
 559                 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
 560                 current->sas_ss_size = SIGSTKSZ;
 561         }
 562         ret = 0;
 563 out:
 564         return ret;
 565 }