1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Architecture-specific signal handling support. 4 * 5 * Copyright (C) 1999-2004 Hewlett-Packard Co 6 * David Mosberger-Tang <davidm@hpl.hp.com> 7 * 8 * Derived from i386 and Alpha versions. 9 */ 10 11 #include <linux/errno.h> 12 #include <linux/kernel.h> 13 #include <linux/mm.h> 14 #include <linux/ptrace.h> 15 #include <linux/tracehook.h> 16 #include <linux/sched.h> 17 #include <linux/signal.h> 18 #include <linux/smp.h> 19 #include <linux/stddef.h> 20 #include <linux/tty.h> 21 #include <linux/binfmts.h> 22 #include <linux/unistd.h> 23 #include <linux/wait.h> 24 25 #include <asm/intrinsics.h> 26 #include <linux/uaccess.h> 27 #include <asm/rse.h> 28 #include <asm/sigcontext.h> 29 30 #include "sigframe.h" 31 32 #define DEBUG_SIG 0 33 #define STACK_ALIGN 16 /* minimal alignment for stack pointer */ 34 35 #if _NSIG_WORDS > 1 36 # define PUT_SIGSET(k,u) __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t)) 37 # define GET_SIGSET(k,u) __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t)) 38 #else 39 # define PUT_SIGSET(k,u) __put_user((k)->sig[0], &(u)->sig[0]) 40 # define GET_SIGSET(k,u) __get_user((k)->sig[0], &(u)->sig[0]) 41 #endif 42 43 static long 44 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr) 45 { 46 unsigned long ip, flags, nat, um, cfm, rsc; 47 long err; 48 49 /* Always make any pending restarted system calls return -EINTR */ 50 current->restart_block.fn = do_no_restart_syscall; 51 52 /* restore scratch that always needs gets updated during signal delivery: */ 53 err = __get_user(flags, &sc->sc_flags); 54 err |= __get_user(nat, &sc->sc_nat); 55 err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */ 56 err |= __get_user(cfm, &sc->sc_cfm); 57 err |= __get_user(um, &sc->sc_um); /* user mask */ 58 err |= __get_user(rsc, &sc->sc_ar_rsc); 59 err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat); 60 err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); 61 err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 62 err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 63 err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 64 err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 65 err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */ 66 err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */ 67 err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */ 68 err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */ 69 70 scr->pt.cr_ifs = cfm | (1UL << 63); 71 scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */ 72 73 /* establish new instruction pointer: */ 74 scr->pt.cr_iip = ip & ~0x3UL; 75 ia64_psr(&scr->pt)->ri = ip & 0x3; 76 scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM); 77 78 scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat); 79 80 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 81 /* Restore most scratch-state only when not in syscall. */ 82 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 83 err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 84 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 85 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */ 86 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */ 87 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */ 88 } 89 90 if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) { 91 struct ia64_psr *psr = ia64_psr(&scr->pt); 92 93 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16); 94 psr->mfh = 0; /* drop signal handler's fph contents... */ 95 preempt_disable(); 96 if (psr->dfh) 97 ia64_drop_fpu(current); 98 else { 99 /* We already own the local fph, otherwise psr->dfh wouldn't be 0. */ 100 __ia64_load_fpu(current->thread.fph); 101 ia64_set_local_fpu_owner(current); 102 } 103 preempt_enable(); 104 } 105 return err; 106 } 107 108 long 109 ia64_rt_sigreturn (struct sigscratch *scr) 110 { 111 extern char ia64_strace_leave_kernel, ia64_leave_kernel; 112 struct sigcontext __user *sc; 113 struct siginfo si; 114 sigset_t set; 115 long retval; 116 117 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc; 118 119 /* 120 * When we return to the previously executing context, r8 and r10 have already 121 * been setup the way we want them. Indeed, if the signal wasn't delivered while 122 * in a system call, we must not touch r8 or r10 as otherwise user-level state 123 * could be corrupted. 124 */ 125 retval = (long) &ia64_leave_kernel; 126 if (test_thread_flag(TIF_SYSCALL_TRACE) 127 || test_thread_flag(TIF_SYSCALL_AUDIT)) 128 /* 129 * strace expects to be notified after sigreturn returns even though the 130 * context to which we return may not be in the middle of a syscall. 131 * Thus, the return-value that strace displays for sigreturn is 132 * meaningless. 133 */ 134 retval = (long) &ia64_strace_leave_kernel; 135 136 if (!access_ok(VERIFY_READ, sc, sizeof(*sc))) 137 goto give_sigsegv; 138 139 if (GET_SIGSET(&set, &sc->sc_mask)) 140 goto give_sigsegv; 141 142 set_current_blocked(&set); 143 144 if (restore_sigcontext(sc, scr)) 145 goto give_sigsegv; 146 147 #if DEBUG_SIG 148 printk("SIG return (%s:%d): sp=%lx ip=%lx\n", 149 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip); 150 #endif 151 if (restore_altstack(&sc->sc_stack)) 152 goto give_sigsegv; 153 return retval; 154 155 give_sigsegv: 156 clear_siginfo(&si); 157 si.si_signo = SIGSEGV; 158 si.si_errno = 0; 159 si.si_code = SI_KERNEL; 160 si.si_pid = task_pid_vnr(current); 161 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 162 si.si_addr = sc; 163 force_sig_info(SIGSEGV, &si, current); 164 return retval; 165 } 166 167 /* 168 * This does just the minimum required setup of sigcontext. 169 * Specifically, it only installs data that is either not knowable at 170 * the user-level or that gets modified before execution in the 171 * trampoline starts. Everything else is done at the user-level. 172 */ 173 static long 174 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr) 175 { 176 unsigned long flags = 0, ifs, cfm, nat; 177 long err = 0; 178 179 ifs = scr->pt.cr_ifs; 180 181 if (on_sig_stack((unsigned long) sc)) 182 flags |= IA64_SC_FLAG_ONSTACK; 183 if ((ifs & (1UL << 63)) == 0) 184 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */ 185 flags |= IA64_SC_FLAG_IN_SYSCALL; 186 cfm = ifs & ((1UL << 38) - 1); 187 ia64_flush_fph(current); 188 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) { 189 flags |= IA64_SC_FLAG_FPH_VALID; 190 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16); 191 } 192 193 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat); 194 195 err |= __put_user(flags, &sc->sc_flags); 196 err |= __put_user(nat, &sc->sc_nat); 197 err |= PUT_SIGSET(mask, &sc->sc_mask); 198 err |= __put_user(cfm, &sc->sc_cfm); 199 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um); 200 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc); 201 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */ 202 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */ 203 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 204 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 205 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 206 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 207 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */ 208 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */ 209 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */ 210 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */ 211 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip); 212 213 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 214 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */ 215 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 216 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 217 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 218 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */ 219 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */ 220 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */ 221 } 222 return err; 223 } 224 225 /* 226 * Check whether the register-backing store is already on the signal stack. 227 */ 228 static inline int 229 rbs_on_sig_stack (unsigned long bsp) 230 { 231 return (bsp - current->sas_ss_sp < current->sas_ss_size); 232 } 233 234 static long 235 force_sigsegv_info (int sig, void __user *addr) 236 { 237 unsigned long flags; 238 struct siginfo si; 239 240 clear_siginfo(&si); 241 if (sig == SIGSEGV) { 242 /* 243 * Acquiring siglock around the sa_handler-update is almost 244 * certainly overkill, but this isn't a 245 * performance-critical path and I'd rather play it safe 246 * here than having to debug a nasty race if and when 247 * something changes in kernel/signal.c that would make it 248 * no longer safe to modify sa_handler without holding the 249 * lock. 250 */ 251 spin_lock_irqsave(¤t->sighand->siglock, flags); 252 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 253 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 254 } 255 si.si_signo = SIGSEGV; 256 si.si_errno = 0; 257 si.si_code = SI_KERNEL; 258 si.si_pid = task_pid_vnr(current); 259 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 260 si.si_addr = addr; 261 force_sig_info(SIGSEGV, &si, current); 262 return 1; 263 } 264 265 static long 266 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr) 267 { 268 extern char __kernel_sigtramp[]; 269 unsigned long tramp_addr, new_rbs = 0, new_sp; 270 struct sigframe __user *frame; 271 long err; 272 273 new_sp = scr->pt.r12; 274 tramp_addr = (unsigned long) __kernel_sigtramp; 275 if (ksig->ka.sa.sa_flags & SA_ONSTACK) { 276 int onstack = sas_ss_flags(new_sp); 277 278 if (onstack == 0) { 279 new_sp = current->sas_ss_sp + current->sas_ss_size; 280 /* 281 * We need to check for the register stack being on the 282 * signal stack separately, because it's switched 283 * separately (memory stack is switched in the kernel, 284 * register stack is switched in the signal trampoline). 285 */ 286 if (!rbs_on_sig_stack(scr->pt.ar_bspstore)) 287 new_rbs = ALIGN(current->sas_ss_sp, 288 sizeof(long)); 289 } else if (onstack == SS_ONSTACK) { 290 unsigned long check_sp; 291 292 /* 293 * If we are on the alternate signal stack and would 294 * overflow it, don't. Return an always-bogus address 295 * instead so we will die with SIGSEGV. 296 */ 297 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN; 298 if (!likely(on_sig_stack(check_sp))) 299 return force_sigsegv_info(ksig->sig, (void __user *) 300 check_sp); 301 } 302 } 303 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN); 304 305 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 306 return force_sigsegv_info(ksig->sig, frame); 307 308 err = __put_user(ksig->sig, &frame->arg0); 309 err |= __put_user(&frame->info, &frame->arg1); 310 err |= __put_user(&frame->sc, &frame->arg2); 311 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base); 312 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */ 313 err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler); 314 315 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 316 317 err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12); 318 err |= setup_sigcontext(&frame->sc, set, scr); 319 320 if (unlikely(err)) 321 return force_sigsegv_info(ksig->sig, frame); 322 323 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */ 324 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */ 325 scr->pt.cr_iip = tramp_addr; 326 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */ 327 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */ 328 /* 329 * Force the interruption function mask to zero. This has no effect when a 330 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is 331 * ignored), but it has the desirable effect of making it possible to deliver a 332 * signal with an incomplete register frame (which happens when a mandatory RSE 333 * load faults). Furthermore, it has no negative effect on the getting the user's 334 * dirty partition preserved, because that's governed by scr->pt.loadrs. 335 */ 336 scr->pt.cr_ifs = (1UL << 63); 337 338 /* 339 * Note: this affects only the NaT bits of the scratch regs (the ones saved in 340 * pt_regs), which is exactly what we want. 341 */ 342 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */ 343 344 #if DEBUG_SIG 345 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n", 346 current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler); 347 #endif 348 return 0; 349 } 350 351 static long 352 handle_signal (struct ksignal *ksig, struct sigscratch *scr) 353 { 354 int ret = setup_frame(ksig, sigmask_to_save(), scr); 355 356 if (!ret) 357 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 358 359 return ret; 360 } 361 362 /* 363 * Note that `init' is a special process: it doesn't get signals it doesn't want to 364 * handle. Thus you cannot kill init even with a SIGKILL even by mistake. 365 */ 366 void 367 ia64_do_signal (struct sigscratch *scr, long in_syscall) 368 { 369 long restart = in_syscall; 370 long errno = scr->pt.r8; 371 struct ksignal ksig; 372 373 /* 374 * This only loops in the rare cases of handle_signal() failing, in which case we 375 * need to push through a forced SIGSEGV. 376 */ 377 while (1) { 378 get_signal(&ksig); 379 380 /* 381 * get_signal_to_deliver() may have run a debugger (via notify_parent()) 382 * and the debugger may have modified the state (e.g., to arrange for an 383 * inferior call), thus it's important to check for restarting _after_ 384 * get_signal_to_deliver(). 385 */ 386 if ((long) scr->pt.r10 != -1) 387 /* 388 * A system calls has to be restarted only if one of the error codes 389 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10 390 * isn't -1 then r8 doesn't hold an error code and we don't need to 391 * restart the syscall, so we can clear the "restart" flag here. 392 */ 393 restart = 0; 394 395 if (ksig.sig <= 0) 396 break; 397 398 if (unlikely(restart)) { 399 switch (errno) { 400 case ERESTART_RESTARTBLOCK: 401 case ERESTARTNOHAND: 402 scr->pt.r8 = EINTR; 403 /* note: scr->pt.r10 is already -1 */ 404 break; 405 406 case ERESTARTSYS: 407 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) { 408 scr->pt.r8 = EINTR; 409 /* note: scr->pt.r10 is already -1 */ 410 break; 411 } 412 case ERESTARTNOINTR: 413 ia64_decrement_ip(&scr->pt); 414 restart = 0; /* don't restart twice if handle_signal() fails... */ 415 } 416 } 417 418 /* 419 * Whee! Actually deliver the signal. If the delivery failed, we need to 420 * continue to iterate in this loop so we can deliver the SIGSEGV... 421 */ 422 if (handle_signal(&ksig, scr)) 423 return; 424 } 425 426 /* Did we come from a system call? */ 427 if (restart) { 428 /* Restart the system call - no handlers present */ 429 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR 430 || errno == ERESTART_RESTARTBLOCK) 431 { 432 /* 433 * Note: the syscall number is in r15 which is saved in 434 * pt_regs so all we need to do here is adjust ip so that 435 * the "break" instruction gets re-executed. 436 */ 437 ia64_decrement_ip(&scr->pt); 438 if (errno == ERESTART_RESTARTBLOCK) 439 scr->pt.r15 = __NR_restart_syscall; 440 } 441 } 442 443 /* if there's no signal to deliver, we just put the saved sigmask 444 * back */ 445 restore_saved_sigmask(); 446 } 447