arch/alpha/kernel/signal.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
SYSCALL_DEFINE2
SYSCALL_DEFINE3
SYSCALL_DEFINE5
restore_sigcontext
do_sigreturn
do_rt_sigreturn
get_sigframe
setup_sigcontext
setup_frame
setup_rt_frame
handle_signal
syscall_restart
do_signal
do_work_pending
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/alpha/kernel/signal.c
   4  *
   5  *  Copyright (C) 1995  Linus Torvalds
   6  *
   7  *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
   8  */
   9 
  10 #include <linux/sched/signal.h>
  11 #include <linux/sched/task_stack.h>
  12 #include <linux/kernel.h>
  13 #include <linux/signal.h>
  14 #include <linux/errno.h>
  15 #include <linux/wait.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/unistd.h>
  18 #include <linux/mm.h>
  19 #include <linux/smp.h>
  20 #include <linux/stddef.h>
  21 #include <linux/tty.h>
  22 #include <linux/binfmts.h>
  23 #include <linux/bitops.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/tracehook.h>
  26 
  27 #include <linux/uaccess.h>
  28 #include <asm/sigcontext.h>
  29 #include <asm/ucontext.h>
  30 
  31 #include "proto.h"
  32 
  33 
  34 #define DEBUG_SIG 0
  35 
  36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  37 
  38 asmlinkage void ret_from_sys_call(void);
  39 
  40 /*
  41  * The OSF/1 sigprocmask calling sequence is different from the
  42  * C sigprocmask() sequence..
  43  */
  44 SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
  45 {
  46         sigset_t oldmask;
  47         sigset_t mask;
  48         unsigned long res;
  49 
  50         siginitset(&mask, newmask & _BLOCKABLE);
  51         res = sigprocmask(how, &mask, &oldmask);
  52         if (!res) {
  53                 force_successful_syscall_return();
  54                 res = oldmask.sig[0];
  55         }
  56         return res;
  57 }
  58 
  59 SYSCALL_DEFINE3(osf_sigaction, int, sig,
  60                 const struct osf_sigaction __user *, act,
  61                 struct osf_sigaction __user *, oact)
  62 {
  63         struct k_sigaction new_ka, old_ka;
  64         int ret;
  65 
  66         if (act) {
  67                 old_sigset_t mask;
  68                 if (!access_ok(act, sizeof(*act)) ||
  69                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  70                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  71                     __get_user(mask, &act->sa_mask))
  72                         return -EFAULT;
  73                 siginitset(&new_ka.sa.sa_mask, mask);
  74                 new_ka.ka_restorer = NULL;
  75         }
  76 
  77         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  78 
  79         if (!ret && oact) {
  80                 if (!access_ok(oact, sizeof(*oact)) ||
  81                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  82                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  83                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  84                         return -EFAULT;
  85         }
  86 
  87         return ret;
  88 }
  89 
  90 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
  91                 struct sigaction __user *, oact,
  92                 size_t, sigsetsize, void __user *, restorer)
  93 {
  94         struct k_sigaction new_ka, old_ka;
  95         int ret;
  96 
  97         /* XXX: Don't preclude handling different sized sigset_t's.  */
  98         if (sigsetsize != sizeof(sigset_t))
  99                 return -EINVAL;
 100 
 101         if (act) {
 102                 new_ka.ka_restorer = restorer;
 103                 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
 104                         return -EFAULT;
 105         }
 106 
 107         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 108 
 109         if (!ret && oact) {
 110                 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
 111                         return -EFAULT;
 112         }
 113 
 114         return ret;
 115 }
 116 
 117 /*
 118  * Do a signal return; undo the signal stack.
 119  */
 120 
 121 #if _NSIG_WORDS > 1
 122 # error "Non SA_SIGINFO frame needs rearranging"
 123 #endif
 124 
 125 struct sigframe
 126 {
 127         struct sigcontext sc;
 128         unsigned int retcode[3];
 129 };
 130 
 131 struct rt_sigframe
 132 {
 133         struct siginfo info;
 134         struct ucontext uc;
 135         unsigned int retcode[3];
 136 };
 137 
 138 /* If this changes, userland unwinders that Know Things about our signal
 139    frame will break.  Do not undertake lightly.  It also implies an ABI
 140    change wrt the size of siginfo_t, which may cause some pain.  */
 141 extern char compile_time_assert
 142         [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
 143 
 144 #define INSN_MOV_R30_R16        0x47fe0410
 145 #define INSN_LDI_R0             0x201f0000
 146 #define INSN_CALLSYS            0x00000083
 147 
 148 static long
 149 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 150 {
 151         unsigned long usp;
 152         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 153         long i, err = __get_user(regs->pc, &sc->sc_pc);
 154 
 155         current->restart_block.fn = do_no_restart_syscall;
 156 
 157         sw->r26 = (unsigned long) ret_from_sys_call;
 158 
 159         err |= __get_user(regs->r0, sc->sc_regs+0);
 160         err |= __get_user(regs->r1, sc->sc_regs+1);
 161         err |= __get_user(regs->r2, sc->sc_regs+2);
 162         err |= __get_user(regs->r3, sc->sc_regs+3);
 163         err |= __get_user(regs->r4, sc->sc_regs+4);
 164         err |= __get_user(regs->r5, sc->sc_regs+5);
 165         err |= __get_user(regs->r6, sc->sc_regs+6);
 166         err |= __get_user(regs->r7, sc->sc_regs+7);
 167         err |= __get_user(regs->r8, sc->sc_regs+8);
 168         err |= __get_user(sw->r9, sc->sc_regs+9);
 169         err |= __get_user(sw->r10, sc->sc_regs+10);
 170         err |= __get_user(sw->r11, sc->sc_regs+11);
 171         err |= __get_user(sw->r12, sc->sc_regs+12);
 172         err |= __get_user(sw->r13, sc->sc_regs+13);
 173         err |= __get_user(sw->r14, sc->sc_regs+14);
 174         err |= __get_user(sw->r15, sc->sc_regs+15);
 175         err |= __get_user(regs->r16, sc->sc_regs+16);
 176         err |= __get_user(regs->r17, sc->sc_regs+17);
 177         err |= __get_user(regs->r18, sc->sc_regs+18);
 178         err |= __get_user(regs->r19, sc->sc_regs+19);
 179         err |= __get_user(regs->r20, sc->sc_regs+20);
 180         err |= __get_user(regs->r21, sc->sc_regs+21);
 181         err |= __get_user(regs->r22, sc->sc_regs+22);
 182         err |= __get_user(regs->r23, sc->sc_regs+23);
 183         err |= __get_user(regs->r24, sc->sc_regs+24);
 184         err |= __get_user(regs->r25, sc->sc_regs+25);
 185         err |= __get_user(regs->r26, sc->sc_regs+26);
 186         err |= __get_user(regs->r27, sc->sc_regs+27);
 187         err |= __get_user(regs->r28, sc->sc_regs+28);
 188         err |= __get_user(regs->gp, sc->sc_regs+29);
 189         err |= __get_user(usp, sc->sc_regs+30);
 190         wrusp(usp);
 191 
 192         for (i = 0; i < 31; i++)
 193                 err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
 194         err |= __get_user(sw->fp[31], &sc->sc_fpcr);
 195 
 196         return err;
 197 }
 198 
 199 /* Note that this syscall is also used by setcontext(3) to install
 200    a given sigcontext.  This because it's impossible to set *all*
 201    registers and transfer control from userland.  */
 202 
 203 asmlinkage void
 204 do_sigreturn(struct sigcontext __user *sc)
 205 {
 206         struct pt_regs *regs = current_pt_regs();
 207         sigset_t set;
 208 
 209         /* Verify that it's a good sigcontext before using it */
 210         if (!access_ok(sc, sizeof(*sc)))
 211                 goto give_sigsegv;
 212         if (__get_user(set.sig[0], &sc->sc_mask))
 213                 goto give_sigsegv;
 214 
 215         set_current_blocked(&set);
 216 
 217         if (restore_sigcontext(sc, regs))
 218                 goto give_sigsegv;
 219 
 220         /* Send SIGTRAP if we're single-stepping: */
 221         if (ptrace_cancel_bpt (current)) {
 222                 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
 223                                current);
 224         }
 225         return;
 226 
 227 give_sigsegv:
 228         force_sig(SIGSEGV);
 229 }
 230 
 231 asmlinkage void
 232 do_rt_sigreturn(struct rt_sigframe __user *frame)
 233 {
 234         struct pt_regs *regs = current_pt_regs();
 235         sigset_t set;
 236 
 237         /* Verify that it's a good ucontext_t before using it */
 238         if (!access_ok(&frame->uc, sizeof(frame->uc)))
 239                 goto give_sigsegv;
 240         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 241                 goto give_sigsegv;
 242 
 243         set_current_blocked(&set);
 244 
 245         if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 246                 goto give_sigsegv;
 247 
 248         /* Send SIGTRAP if we're single-stepping: */
 249         if (ptrace_cancel_bpt (current)) {
 250                 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
 251                                current);
 252         }
 253         return;
 254 
 255 give_sigsegv:
 256         force_sig(SIGSEGV);
 257 }
 258 
 259 
 260 /*
 261  * Set up a signal frame.
 262  */
 263 
 264 static inline void __user *
 265 get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
 266 {
 267         return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
 268 }
 269 
 270 static long
 271 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 
 272                  unsigned long mask, unsigned long sp)
 273 {
 274         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 275         long i, err = 0;
 276 
 277         err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
 278         err |= __put_user(mask, &sc->sc_mask);
 279         err |= __put_user(regs->pc, &sc->sc_pc);
 280         err |= __put_user(8, &sc->sc_ps);
 281 
 282         err |= __put_user(regs->r0 , sc->sc_regs+0);
 283         err |= __put_user(regs->r1 , sc->sc_regs+1);
 284         err |= __put_user(regs->r2 , sc->sc_regs+2);
 285         err |= __put_user(regs->r3 , sc->sc_regs+3);
 286         err |= __put_user(regs->r4 , sc->sc_regs+4);
 287         err |= __put_user(regs->r5 , sc->sc_regs+5);
 288         err |= __put_user(regs->r6 , sc->sc_regs+6);
 289         err |= __put_user(regs->r7 , sc->sc_regs+7);
 290         err |= __put_user(regs->r8 , sc->sc_regs+8);
 291         err |= __put_user(sw->r9   , sc->sc_regs+9);
 292         err |= __put_user(sw->r10  , sc->sc_regs+10);
 293         err |= __put_user(sw->r11  , sc->sc_regs+11);
 294         err |= __put_user(sw->r12  , sc->sc_regs+12);
 295         err |= __put_user(sw->r13  , sc->sc_regs+13);
 296         err |= __put_user(sw->r14  , sc->sc_regs+14);
 297         err |= __put_user(sw->r15  , sc->sc_regs+15);
 298         err |= __put_user(regs->r16, sc->sc_regs+16);
 299         err |= __put_user(regs->r17, sc->sc_regs+17);
 300         err |= __put_user(regs->r18, sc->sc_regs+18);
 301         err |= __put_user(regs->r19, sc->sc_regs+19);
 302         err |= __put_user(regs->r20, sc->sc_regs+20);
 303         err |= __put_user(regs->r21, sc->sc_regs+21);
 304         err |= __put_user(regs->r22, sc->sc_regs+22);
 305         err |= __put_user(regs->r23, sc->sc_regs+23);
 306         err |= __put_user(regs->r24, sc->sc_regs+24);
 307         err |= __put_user(regs->r25, sc->sc_regs+25);
 308         err |= __put_user(regs->r26, sc->sc_regs+26);
 309         err |= __put_user(regs->r27, sc->sc_regs+27);
 310         err |= __put_user(regs->r28, sc->sc_regs+28);
 311         err |= __put_user(regs->gp , sc->sc_regs+29);
 312         err |= __put_user(sp, sc->sc_regs+30);
 313         err |= __put_user(0, sc->sc_regs+31);
 314 
 315         for (i = 0; i < 31; i++)
 316                 err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
 317         err |= __put_user(0, sc->sc_fpregs+31);
 318         err |= __put_user(sw->fp[31], &sc->sc_fpcr);
 319 
 320         err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
 321         err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
 322         err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
 323 
 324         return err;
 325 }
 326 
 327 static int
 328 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 329 {
 330         unsigned long oldsp, r26, err = 0;
 331         struct sigframe __user *frame;
 332 
 333         oldsp = rdusp();
 334         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 335         if (!access_ok(frame, sizeof(*frame)))
 336                 return -EFAULT;
 337 
 338         err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 339         if (err)
 340                 return -EFAULT;
 341 
 342         /* Set up to return from userspace.  If provided, use a stub
 343            already in userspace.  */
 344         r26 = (unsigned long) ksig->ka.ka_restorer;
 345         if (!r26) {
 346                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 347                 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
 348                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 349                 imb();
 350                 r26 = (unsigned long) frame->retcode;
 351         }
 352 
 353         /* Check that everything was written properly.  */
 354         if (err)
 355                 return err;
 356 
 357         /* "Return" to the handler */
 358         regs->r26 = r26;
 359         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 360         regs->r16 = ksig->sig;                  /* a0: signal number */
 361         regs->r17 = 0;                          /* a1: exception code */
 362         regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
 363         wrusp((unsigned long) frame);
 364         
 365 #if DEBUG_SIG
 366         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 367                 current->comm, current->pid, frame, regs->pc, regs->r26);
 368 #endif
 369         return 0;
 370 }
 371 
 372 static int
 373 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 374 {
 375         unsigned long oldsp, r26, err = 0;
 376         struct rt_sigframe __user *frame;
 377 
 378         oldsp = rdusp();
 379         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 380         if (!access_ok(frame, sizeof(*frame)))
 381                 return -EFAULT;
 382 
 383         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 384 
 385         /* Create the ucontext.  */
 386         err |= __put_user(0, &frame->uc.uc_flags);
 387         err |= __put_user(0, &frame->uc.uc_link);
 388         err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
 389         err |= __save_altstack(&frame->uc.uc_stack, oldsp);
 390         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 
 391                                 set->sig[0], oldsp);
 392         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 393         if (err)
 394                 return -EFAULT;
 395 
 396         /* Set up to return from userspace.  If provided, use a stub
 397            already in userspace.  */
 398         r26 = (unsigned long) ksig->ka.ka_restorer;
 399         if (!r26) {
 400                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 401                 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
 402                                   frame->retcode+1);
 403                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 404                 imb();
 405                 r26 = (unsigned long) frame->retcode;
 406         }
 407 
 408         if (err)
 409                 return -EFAULT;
 410 
 411         /* "Return" to the handler */
 412         regs->r26 = r26;
 413         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 414         regs->r16 = ksig->sig;                    /* a0: signal number */
 415         regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
 416         regs->r18 = (unsigned long) &frame->uc;   /* a2: ucontext pointer */
 417         wrusp((unsigned long) frame);
 418 
 419 #if DEBUG_SIG
 420         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 421                 current->comm, current->pid, frame, regs->pc, regs->r26);
 422 #endif
 423 
 424         return 0;
 425 }
 426 
 427 
 428 /*
 429  * OK, we're invoking a handler.
 430  */
 431 static inline void
 432 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 433 {
 434         sigset_t *oldset = sigmask_to_save();
 435         int ret;
 436 
 437         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 438                 ret = setup_rt_frame(ksig, oldset, regs);
 439         else
 440                 ret = setup_frame(ksig, oldset, regs);
 441 
 442         signal_setup_done(ret, ksig, 0);
 443 }
 444 
 445 static inline void
 446 syscall_restart(unsigned long r0, unsigned long r19,
 447                 struct pt_regs *regs, struct k_sigaction *ka)
 448 {
 449         switch (regs->r0) {
 450         case ERESTARTSYS:
 451                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 452                 case ERESTARTNOHAND:
 453                         regs->r0 = EINTR;
 454                         break;
 455                 }
 456                 /* fallthrough */
 457         case ERESTARTNOINTR:
 458                 regs->r0 = r0;  /* reset v0 and a3 and replay syscall */
 459                 regs->r19 = r19;
 460                 regs->pc -= 4;
 461                 break;
 462         case ERESTART_RESTARTBLOCK:
 463                 regs->r0 = EINTR;
 464                 break;
 465         }
 466 }
 467 
 468 
 469 /*
 470  * Note that 'init' is a special process: it doesn't get signals it doesn't
 471  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 472  * mistake.
 473  *
 474  * Note that we go through the signals twice: once to check the signals that
 475  * the kernel can handle, and then we build all the user-level signal handling
 476  * stack-frames in one go after that.
 477  *
 478  * "r0" and "r19" are the registers we need to restore for system call
 479  * restart. "r0" is also used as an indicator whether we can restart at
 480  * all (if we get here from anything but a syscall return, it will be 0)
 481  */
 482 static void
 483 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 484 {
 485         unsigned long single_stepping = ptrace_cancel_bpt(current);
 486         struct ksignal ksig;
 487 
 488         /* This lets the debugger run, ... */
 489         if (get_signal(&ksig)) {
 490                 /* ... so re-check the single stepping. */
 491                 single_stepping |= ptrace_cancel_bpt(current);
 492                 /* Whee!  Actually deliver the signal.  */
 493                 if (r0)
 494                         syscall_restart(r0, r19, regs, &ksig.ka);
 495                 handle_signal(&ksig, regs);
 496         } else {
 497                 single_stepping |= ptrace_cancel_bpt(current);
 498                 if (r0) {
 499                         switch (regs->r0) {
 500                         case ERESTARTNOHAND:
 501                         case ERESTARTSYS:
 502                         case ERESTARTNOINTR:
 503                                 /* Reset v0 and a3 and replay syscall.  */
 504                                 regs->r0 = r0;
 505                                 regs->r19 = r19;
 506                                 regs->pc -= 4;
 507                                 break;
 508                         case ERESTART_RESTARTBLOCK:
 509                                 /* Set v0 to the restart_syscall and replay */
 510                                 regs->r0 = __NR_restart_syscall;
 511                                 regs->pc -= 4;
 512                                 break;
 513                         }
 514                 }
 515                 restore_saved_sigmask();
 516         }
 517         if (single_stepping)
 518                 ptrace_set_bpt(current);        /* re-set breakpoint */
 519 }
 520 
 521 void
 522 do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 523                  unsigned long r0, unsigned long r19)
 524 {
 525         do {
 526                 if (thread_flags & _TIF_NEED_RESCHED) {
 527                         schedule();
 528                 } else {
 529                         local_irq_enable();
 530                         if (thread_flags & _TIF_SIGPENDING) {
 531                                 do_signal(regs, r0, r19);
 532                                 r0 = 0;
 533                         } else {
 534                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 535                                 tracehook_notify_resume(regs);
 536                         }
 537                 }
 538                 local_irq_disable();
 539                 thread_flags = current_thread_info()->flags;
 540         } while (thread_flags & _TIF_WORK_MASK);
 541 }
/* [<][>][^][v][top][bottom][index][help] */
root/arch/alpha/kernel/signal.c

DEFINITIONS
