root/arch/sparc/kernel/signal_32.c

DEFINITIONS

1. do_sigreturn
2. do_rt_sigreturn
3. get_sigframe
4. setup_frame
5. setup_rt_frame
6. handle_signal
7. syscall_restart
8. do_signal
9. do_notify_resume
10. do_sys_sigstack

   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/tracehook.h>
  23 
  24 #include <linux/uaccess.h>
  25 #include <asm/ptrace.h>
  26 #include <asm/pgalloc.h>
  27 #include <asm/pgtable.h>
  28 #include <asm/cacheflush.h>     /* flush_sig_insns */
  29 #include <asm/switch_to.h>
  30 
  31 #include "sigutil.h"
  32 #include "kernel.h"
  33 
  34 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
  35                    void *fpqueue, unsigned long *fpqdepth);
  36 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
  37 
  38 struct signal_frame {
  39         struct sparc_stackf     ss;
  40         __siginfo32_t           info;
  41         __siginfo_fpu_t __user  *fpu_save;
  42         unsigned long           insns[2] __attribute__ ((aligned (8)));
  43         unsigned int            extramask[_NSIG_WORDS - 1];
  44         unsigned int            extra_size; /* Should be 0 */
  45         __siginfo_rwin_t __user *rwin_save;
  46 } __attribute__((aligned(8)));
  47 
  48 struct rt_signal_frame {
  49         struct sparc_stackf     ss;
  50         siginfo_t               info;
  51         struct pt_regs          regs;
  52         sigset_t                mask;
  53         __siginfo_fpu_t __user  *fpu_save;
  54         unsigned int            insns[2];
  55         stack_t                 stack;
  56         unsigned int            extra_size; /* Should be 0 */
  57         __siginfo_rwin_t __user *rwin_save;
  58 } __attribute__((aligned(8)));
  59 
  60 /* Align macros */
  61 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
  62 #define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))
  63 
  64 /* Checks if the fp is valid.  We always build signal frames which are
  65  * 16-byte aligned, therefore we can always enforce that the restore
  66  * frame has that property as well.
  67  */
  68 static inline bool invalid_frame_pointer(void __user *fp, int fplen)
  69 {
  70         if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen))
  71                 return true;
  72 
  73         return false;
  74 }
  75 
  76 asmlinkage void do_sigreturn(struct pt_regs *regs)
  77 {
  78         unsigned long up_psr, pc, npc, ufp;
  79         struct signal_frame __user *sf;
  80         sigset_t set;
  81         __siginfo_fpu_t __user *fpu_save;
  82         __siginfo_rwin_t __user *rwin_save;
  83         int err;
  84 
  85         /* Always make any pending restarted system calls return -EINTR */
  86         current->restart_block.fn = do_no_restart_syscall;
  87 
  88         synchronize_user_stack();
  89 
  90         sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
  91 
  92         /* 1. Make sure we are not getting garbage from the user */
  93         if (invalid_frame_pointer(sf, sizeof(*sf)))
  94                 goto segv_and_exit;
  95 
  96         if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP]))
  97                 goto segv_and_exit;
  98 
  99         if (ufp & 0x7)
 100                 goto segv_and_exit;
 101 
 102         err = __get_user(pc,  &sf->info.si_regs.pc);
 103         err |= __get_user(npc, &sf->info.si_regs.npc);
 104 
 105         if ((pc | npc) & 3)
 106                 goto segv_and_exit;
 107 
 108         /* 2. Restore the state */
 109         up_psr = regs->psr;
 110         err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
 111 
 112         /* User can only change condition codes and FPU enabling in %psr. */
 113         regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
 114                   | (regs->psr & (PSR_ICC | PSR_EF));
 115 
 116         /* Prevent syscall restart.  */
 117         pt_regs_clear_syscall(regs);
 118 
 119         err |= __get_user(fpu_save, &sf->fpu_save);
 120         if (fpu_save)
 121                 err |= restore_fpu_state(regs, fpu_save);
 122         err |= __get_user(rwin_save, &sf->rwin_save);
 123         if (rwin_save)
 124                 err |= restore_rwin_state(rwin_save);
 125 
 126         /* This is pretty much atomic, no amount locking would prevent
 127          * the races which exist anyways.
 128          */
 129         err |= __get_user(set.sig[0], &sf->info.si_mask);
 130         err |= __copy_from_user(&set.sig[1], &sf->extramask,
 131                                 (_NSIG_WORDS-1) * sizeof(unsigned int));
 132                            
 133         if (err)
 134                 goto segv_and_exit;
 135 
 136         set_current_blocked(&set);
 137         return;
 138 
 139 segv_and_exit:
 140         force_sig(SIGSEGV);
 141 }
 142 
 143 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 144 {
 145         struct rt_signal_frame __user *sf;
 146         unsigned int psr, pc, npc, ufp;
 147         __siginfo_fpu_t __user *fpu_save;
 148         __siginfo_rwin_t __user *rwin_save;
 149         sigset_t set;
 150         int err;
 151 
 152         synchronize_user_stack();
 153         sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
 154         if (invalid_frame_pointer(sf, sizeof(*sf)))
 155                 goto segv;
 156 
 157         if (get_user(ufp, &sf->regs.u_regs[UREG_FP]))
 158                 goto segv;
 159 
 160         if (ufp & 0x7)
 161                 goto segv;
 162 
 163         err = __get_user(pc, &sf->regs.pc);
 164         err |= __get_user(npc, &sf->regs.npc);
 165         err |= ((pc | npc) & 0x03);
 166 
 167         err |= __get_user(regs->y, &sf->regs.y);
 168         err |= __get_user(psr, &sf->regs.psr);
 169 
 170         err |= __copy_from_user(&regs->u_regs[UREG_G1],
 171                                 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
 172 
 173         regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
 174 
 175         /* Prevent syscall restart.  */
 176         pt_regs_clear_syscall(regs);
 177 
 178         err |= __get_user(fpu_save, &sf->fpu_save);
 179         if (!err && fpu_save)
 180                 err |= restore_fpu_state(regs, fpu_save);
 181         err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 182         err |= restore_altstack(&sf->stack);
 183         
 184         if (err)
 185                 goto segv;
 186                 
 187         regs->pc = pc;
 188         regs->npc = npc;
 189         
 190         err |= __get_user(rwin_save, &sf->rwin_save);
 191         if (!err && rwin_save) {
 192                 if (restore_rwin_state(rwin_save))
 193                         goto segv;
 194         }
 195 
 196         set_current_blocked(&set);
 197         return;
 198 segv:
 199         force_sig(SIGSEGV);
 200 }
 201 
 202 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
 203 {
 204         unsigned long sp = regs->u_regs[UREG_FP];
 205 
 206         /*
 207          * If we are on the alternate signal stack and would overflow it, don't.
 208          * Return an always-bogus address instead so we will die with SIGSEGV.
 209          */
 210         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 211                 return (void __user *) -1L;
 212 
 213         /* This is the X/Open sanctioned signal stack switching.  */
 214         sp = sigsp(sp, ksig) - framesize;
 215 
 216         /* Always align the stack frame.  This handles two cases.  First,
 217          * sigaltstack need not be mindful of platform specific stack
 218          * alignment.  Second, if we took this signal because the stack
 219          * is not aligned properly, we'd like to take the signal cleanly
 220          * and report that.
 221          */
 222         sp &= ~15UL;
 223 
 224         return (void __user *) sp;
 225 }
 226 
 227 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
 228                        sigset_t *oldset)
 229 {
 230         struct signal_frame __user *sf;
 231         int sigframe_size, err, wsaved;
 232         void __user *tail;
 233 
 234         /* 1. Make sure everything is clean */
 235         synchronize_user_stack();
 236 
 237         wsaved = current_thread_info()->w_saved;
 238 
 239         sigframe_size = sizeof(*sf);
 240         if (used_math())
 241                 sigframe_size += sizeof(__siginfo_fpu_t);
 242         if (wsaved)
 243                 sigframe_size += sizeof(__siginfo_rwin_t);
 244 
 245         sf = (struct signal_frame __user *)
 246                 get_sigframe(ksig, regs, sigframe_size);
 247 
 248         if (invalid_frame_pointer(sf, sigframe_size)) {
 249                 do_exit(SIGILL);
 250                 return -EINVAL;
 251         }
 252 
 253         tail = sf + 1;
 254 
 255         /* 2. Save the current process state */
 256         err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
 257         
 258         err |= __put_user(0, &sf->extra_size);
 259 
 260         if (used_math()) {
 261                 __siginfo_fpu_t __user *fp = tail;
 262                 tail += sizeof(*fp);
 263                 err |= save_fpu_state(regs, fp);
 264                 err |= __put_user(fp, &sf->fpu_save);
 265         } else {
 266                 err |= __put_user(0, &sf->fpu_save);
 267         }
 268         if (wsaved) {
 269                 __siginfo_rwin_t __user *rwp = tail;
 270                 tail += sizeof(*rwp);
 271                 err |= save_rwin_state(wsaved, rwp);
 272                 err |= __put_user(rwp, &sf->rwin_save);
 273         } else {
 274                 err |= __put_user(0, &sf->rwin_save);
 275         }
 276 
 277         err |= __put_user(oldset->sig[0], &sf->info.si_mask);
 278         err |= __copy_to_user(sf->extramask, &oldset->sig[1],
 279                               (_NSIG_WORDS - 1) * sizeof(unsigned int));
 280         if (!wsaved) {
 281                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 282                                       sizeof(struct reg_window32));
 283         } else {
 284                 struct reg_window32 *rp;
 285 
 286                 rp = &current_thread_info()->reg_window[wsaved - 1];
 287                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 288         }
 289         if (err)
 290                 return err;
 291         
 292         /* 3. signal handler back-trampoline and parameters */
 293         regs->u_regs[UREG_FP] = (unsigned long) sf;
 294         regs->u_regs[UREG_I0] = ksig->sig;
 295         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 296         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
 297 
 298         /* 4. signal handler */
 299         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 300         regs->npc = (regs->pc + 4);
 301 
 302         /* 5. return to kernel instructions */
 303         if (ksig->ka.ka_restorer)
 304                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 305         else {
 306                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 307 
 308                 /* mov __NR_sigreturn, %g1 */
 309                 err |= __put_user(0x821020d8, &sf->insns[0]);
 310 
 311                 /* t 0x10 */
 312                 err |= __put_user(0x91d02010, &sf->insns[1]);
 313                 if (err)
 314                         return err;
 315 
 316                 /* Flush instruction space. */
 317                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 318         }
 319         return 0;
 320 }
 321 
 322 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
 323                           sigset_t *oldset)
 324 {
 325         struct rt_signal_frame __user *sf;
 326         int sigframe_size, wsaved;
 327         void __user *tail;
 328         unsigned int psr;
 329         int err;
 330 
 331         synchronize_user_stack();
 332         wsaved = current_thread_info()->w_saved;
 333         sigframe_size = sizeof(*sf);
 334         if (used_math())
 335                 sigframe_size += sizeof(__siginfo_fpu_t);
 336         if (wsaved)
 337                 sigframe_size += sizeof(__siginfo_rwin_t);
 338         sf = (struct rt_signal_frame __user *)
 339                 get_sigframe(ksig, regs, sigframe_size);
 340         if (invalid_frame_pointer(sf, sigframe_size)) {
 341                 do_exit(SIGILL);
 342                 return -EINVAL;
 343         }
 344 
 345         tail = sf + 1;
 346         err  = __put_user(regs->pc, &sf->regs.pc);
 347         err |= __put_user(regs->npc, &sf->regs.npc);
 348         err |= __put_user(regs->y, &sf->regs.y);
 349         psr = regs->psr;
 350         if (used_math())
 351                 psr |= PSR_EF;
 352         err |= __put_user(psr, &sf->regs.psr);
 353         err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
 354         err |= __put_user(0, &sf->extra_size);
 355 
 356         if (psr & PSR_EF) {
 357                 __siginfo_fpu_t __user *fp = tail;
 358                 tail += sizeof(*fp);
 359                 err |= save_fpu_state(regs, fp);
 360                 err |= __put_user(fp, &sf->fpu_save);
 361         } else {
 362                 err |= __put_user(0, &sf->fpu_save);
 363         }
 364         if (wsaved) {
 365                 __siginfo_rwin_t __user *rwp = tail;
 366                 tail += sizeof(*rwp);
 367                 err |= save_rwin_state(wsaved, rwp);
 368                 err |= __put_user(rwp, &sf->rwin_save);
 369         } else {
 370                 err |= __put_user(0, &sf->rwin_save);
 371         }
 372         err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
 373         
 374         /* Setup sigaltstack */
 375         err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
 376         
 377         if (!wsaved) {
 378                 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 379                                       sizeof(struct reg_window32));
 380         } else {
 381                 struct reg_window32 *rp;
 382 
 383                 rp = &current_thread_info()->reg_window[wsaved - 1];
 384                 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
 385         }
 386 
 387         err |= copy_siginfo_to_user(&sf->info, &ksig->info);
 388 
 389         if (err)
 390                 return err;
 391 
 392         regs->u_regs[UREG_FP] = (unsigned long) sf;
 393         regs->u_regs[UREG_I0] = ksig->sig;
 394         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 395         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
 396 
 397         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 398         regs->npc = (regs->pc + 4);
 399 
 400         if (ksig->ka.ka_restorer)
 401                 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
 402         else {
 403                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 404 
 405                 /* mov __NR_sigreturn, %g1 */
 406                 err |= __put_user(0x821020d8, &sf->insns[0]);
 407 
 408                 /* t 0x10 */
 409                 err |= __put_user(0x91d02010, &sf->insns[1]);
 410                 if (err)
 411                         return err;
 412 
 413                 /* Flush instruction space. */
 414                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 415         }
 416         return 0;
 417 }
 418 
 419 static inline void
 420 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 421 {
 422         sigset_t *oldset = sigmask_to_save();
 423         int err;
 424 
 425         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 426                 err = setup_rt_frame(ksig, regs, oldset);
 427         else
 428                 err = setup_frame(ksig, regs, oldset);
 429         signal_setup_done(err, ksig, 0);
 430 }
 431 
 432 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 433                                    struct sigaction *sa)
 434 {
 435         switch(regs->u_regs[UREG_I0]) {
 436         case ERESTART_RESTARTBLOCK:
 437         case ERESTARTNOHAND:
 438         no_system_call_restart:
 439                 regs->u_regs[UREG_I0] = EINTR;
 440                 regs->psr |= PSR_C;
 441                 break;
 442         case ERESTARTSYS:
 443                 if (!(sa->sa_flags & SA_RESTART))
 444                         goto no_system_call_restart;
 445                 /* fallthrough */
 446         case ERESTARTNOINTR:
 447                 regs->u_regs[UREG_I0] = orig_i0;
 448                 regs->pc -= 4;
 449                 regs->npc -= 4;
 450         }
 451 }
 452 
 453 /* Note that 'init' is a special process: it doesn't get signals it doesn't
 454  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 455  * mistake.
 456  */
 457 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 458 {
 459         struct ksignal ksig;
 460         int restart_syscall;
 461         bool has_handler;
 462 
 463         /* It's a lot of work and synchronization to add a new ptrace
 464          * register for GDB to save and restore in order to get
 465          * orig_i0 correct for syscall restarts when debugging.
 466          *
 467          * Although it should be the case that most of the global
 468          * registers are volatile across a system call, glibc already
 469          * depends upon that fact that we preserve them.  So we can't
 470          * just use any global register to save away the orig_i0 value.
 471          *
 472          * In particular %g2, %g3, %g4, and %g5 are all assumed to be
 473          * preserved across a system call trap by various pieces of
 474          * code in glibc.
 475          *
 476          * %g7 is used as the "thread register".   %g6 is not used in
 477          * any fixed manner.  %g6 is used as a scratch register and
 478          * a compiler temporary, but it's value is never used across
 479          * a system call.  Therefore %g6 is usable for orig_i0 storage.
 480          */
 481         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
 482                 regs->u_regs[UREG_G6] = orig_i0;
 483 
 484         has_handler = get_signal(&ksig);
 485 
 486         /* If the debugger messes with the program counter, it clears
 487          * the software "in syscall" bit, directing us to not perform
 488          * a syscall restart.
 489          */
 490         restart_syscall = 0;
 491         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
 492                 restart_syscall = 1;
 493                 orig_i0 = regs->u_regs[UREG_G6];
 494         }
 495 
 496         if (has_handler) {
 497                 if (restart_syscall)
 498                         syscall_restart(orig_i0, regs, &ksig.ka.sa);
 499                 handle_signal(&ksig, regs);
 500         } else {
 501                 if (restart_syscall) {
 502                         switch (regs->u_regs[UREG_I0]) {
 503                         case ERESTARTNOHAND:
 504                         case ERESTARTSYS:
 505                         case ERESTARTNOINTR:
 506                                 /* replay the system call when we are done */
 507                                 regs->u_regs[UREG_I0] = orig_i0;
 508                                 regs->pc -= 4;
 509                                 regs->npc -= 4;
 510                                 pt_regs_clear_syscall(regs);
 511                                 /* fall through */
 512                         case ERESTART_RESTARTBLOCK:
 513                                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
 514                                 regs->pc -= 4;
 515                                 regs->npc -= 4;
 516                                 pt_regs_clear_syscall(regs);
 517                         }
 518                 }
 519                 restore_saved_sigmask();
 520         }
 521 }
 522 
 523 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
 524                       unsigned long thread_info_flags)
 525 {
 526         if (thread_info_flags & _TIF_SIGPENDING)
 527                 do_signal(regs, orig_i0);
 528         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 529                 clear_thread_flag(TIF_NOTIFY_RESUME);
 530                 tracehook_notify_resume(regs);
 531         }
 532 }
 533 
 534 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr,
 535                                struct sigstack __user *ossptr,
 536                                unsigned long sp)
 537 {
 538         int ret = -EFAULT;
 539 
 540         /* First see if old state is wanted. */
 541         if (ossptr) {
 542                 if (put_user(current->sas_ss_sp + current->sas_ss_size,
 543                              &ossptr->the_stack) ||
 544                     __put_user(on_sig_stack(sp), &ossptr->cur_status))
 545                         goto out;
 546         }
 547 
 548         /* Now see if we want to update the new state. */
 549         if (ssptr) {
 550                 char *ss_sp;
 551 
 552                 if (get_user(ss_sp, &ssptr->the_stack))
 553                         goto out;
 554                 /* If the current stack was set with sigaltstack, don't
 555                    swap stacks while we are on it.  */
 556                 ret = -EPERM;
 557                 if (current->sas_ss_sp && on_sig_stack(sp))
 558                         goto out;
 559 
 560                 /* Since we don't know the extent of the stack, and we don't
 561                    track onstack-ness, but rather calculate it, we must
 562                    presume a size.  Ho hum this interface is lossy.  */
 563                 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
 564                 current->sas_ss_size = SIGSTKSZ;
 565         }
 566         ret = 0;
 567 out:
 568         return ret;
 569 }