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 sigset_t set; 114 long retval; 115 116 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc; 117 118 /* 119 * When we return to the previously executing context, r8 and r10 have already 120 * been setup the way we want them. Indeed, if the signal wasn't delivered while 121 * in a system call, we must not touch r8 or r10 as otherwise user-level state 122 * could be corrupted. 123 */ 124 retval = (long) &ia64_leave_kernel; 125 if (test_thread_flag(TIF_SYSCALL_TRACE) 126 || test_thread_flag(TIF_SYSCALL_AUDIT)) 127 /* 128 * strace expects to be notified after sigreturn returns even though the 129 * context to which we return may not be in the middle of a syscall. 130 * Thus, the return-value that strace displays for sigreturn is 131 * meaningless. 132 */ 133 retval = (long) &ia64_strace_leave_kernel; 134 135 if (!access_ok(sc, sizeof(*sc))) 136 goto give_sigsegv; 137 138 if (GET_SIGSET(&set, &sc->sc_mask)) 139 goto give_sigsegv; 140 141 set_current_blocked(&set); 142 143 if (restore_sigcontext(sc, scr)) 144 goto give_sigsegv; 145 146 #if DEBUG_SIG 147 printk("SIG return (%s:%d): sp=%lx ip=%lx\n", 148 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip); 149 #endif 150 if (restore_altstack(&sc->sc_stack)) 151 goto give_sigsegv; 152 return retval; 153 154 give_sigsegv: 155 force_sig(SIGSEGV); 156 return retval; 157 } 158 159 /* 160 * This does just the minimum required setup of sigcontext. 161 * Specifically, it only installs data that is either not knowable at 162 * the user-level or that gets modified before execution in the 163 * trampoline starts. Everything else is done at the user-level. 164 */ 165 static long 166 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr) 167 { 168 unsigned long flags = 0, ifs, cfm, nat; 169 long err = 0; 170 171 ifs = scr->pt.cr_ifs; 172 173 if (on_sig_stack((unsigned long) sc)) 174 flags |= IA64_SC_FLAG_ONSTACK; 175 if ((ifs & (1UL << 63)) == 0) 176 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */ 177 flags |= IA64_SC_FLAG_IN_SYSCALL; 178 cfm = ifs & ((1UL << 38) - 1); 179 ia64_flush_fph(current); 180 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) { 181 flags |= IA64_SC_FLAG_FPH_VALID; 182 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16); 183 } 184 185 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat); 186 187 err |= __put_user(flags, &sc->sc_flags); 188 err |= __put_user(nat, &sc->sc_nat); 189 err |= PUT_SIGSET(mask, &sc->sc_mask); 190 err |= __put_user(cfm, &sc->sc_cfm); 191 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um); 192 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc); 193 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */ 194 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */ 195 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 196 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 197 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 198 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 199 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */ 200 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */ 201 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */ 202 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */ 203 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip); 204 205 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 206 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */ 207 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 208 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 209 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 210 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */ 211 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */ 212 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */ 213 } 214 return err; 215 } 216 217 /* 218 * Check whether the register-backing store is already on the signal stack. 219 */ 220 static inline int 221 rbs_on_sig_stack (unsigned long bsp) 222 { 223 return (bsp - current->sas_ss_sp < current->sas_ss_size); 224 } 225 226 static long 227 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr) 228 { 229 extern char __kernel_sigtramp[]; 230 unsigned long tramp_addr, new_rbs = 0, new_sp; 231 struct sigframe __user *frame; 232 long err; 233 234 new_sp = scr->pt.r12; 235 tramp_addr = (unsigned long) __kernel_sigtramp; 236 if (ksig->ka.sa.sa_flags & SA_ONSTACK) { 237 int onstack = sas_ss_flags(new_sp); 238 239 if (onstack == 0) { 240 new_sp = current->sas_ss_sp + current->sas_ss_size; 241 /* 242 * We need to check for the register stack being on the 243 * signal stack separately, because it's switched 244 * separately (memory stack is switched in the kernel, 245 * register stack is switched in the signal trampoline). 246 */ 247 if (!rbs_on_sig_stack(scr->pt.ar_bspstore)) 248 new_rbs = ALIGN(current->sas_ss_sp, 249 sizeof(long)); 250 } else if (onstack == SS_ONSTACK) { 251 unsigned long check_sp; 252 253 /* 254 * If we are on the alternate signal stack and would 255 * overflow it, don't. Return an always-bogus address 256 * instead so we will die with SIGSEGV. 257 */ 258 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN; 259 if (!likely(on_sig_stack(check_sp))) { 260 force_sigsegv(ksig->sig); 261 return 1; 262 } 263 } 264 } 265 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN); 266 267 if (!access_ok(frame, sizeof(*frame))) { 268 force_sigsegv(ksig->sig); 269 return 1; 270 } 271 272 err = __put_user(ksig->sig, &frame->arg0); 273 err |= __put_user(&frame->info, &frame->arg1); 274 err |= __put_user(&frame->sc, &frame->arg2); 275 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base); 276 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */ 277 err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler); 278 279 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 280 281 err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12); 282 err |= setup_sigcontext(&frame->sc, set, scr); 283 284 if (unlikely(err)) { 285 force_sigsegv(ksig->sig); 286 return 1; 287 } 288 289 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */ 290 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */ 291 scr->pt.cr_iip = tramp_addr; 292 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */ 293 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */ 294 /* 295 * Force the interruption function mask to zero. This has no effect when a 296 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is 297 * ignored), but it has the desirable effect of making it possible to deliver a 298 * signal with an incomplete register frame (which happens when a mandatory RSE 299 * load faults). Furthermore, it has no negative effect on the getting the user's 300 * dirty partition preserved, because that's governed by scr->pt.loadrs. 301 */ 302 scr->pt.cr_ifs = (1UL << 63); 303 304 /* 305 * Note: this affects only the NaT bits of the scratch regs (the ones saved in 306 * pt_regs), which is exactly what we want. 307 */ 308 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */ 309 310 #if DEBUG_SIG 311 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n", 312 current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler); 313 #endif 314 return 0; 315 } 316 317 static long 318 handle_signal (struct ksignal *ksig, struct sigscratch *scr) 319 { 320 int ret = setup_frame(ksig, sigmask_to_save(), scr); 321 322 if (!ret) 323 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 324 325 return ret; 326 } 327 328 /* 329 * Note that `init' is a special process: it doesn't get signals it doesn't want to 330 * handle. Thus you cannot kill init even with a SIGKILL even by mistake. 331 */ 332 void 333 ia64_do_signal (struct sigscratch *scr, long in_syscall) 334 { 335 long restart = in_syscall; 336 long errno = scr->pt.r8; 337 struct ksignal ksig; 338 339 /* 340 * This only loops in the rare cases of handle_signal() failing, in which case we 341 * need to push through a forced SIGSEGV. 342 */ 343 while (1) { 344 get_signal(&ksig); 345 346 /* 347 * get_signal() may have run a debugger (via notify_parent()) 348 * and the debugger may have modified the state (e.g., to arrange for an 349 * inferior call), thus it's important to check for restarting _after_ 350 * get_signal(). 351 */ 352 if ((long) scr->pt.r10 != -1) 353 /* 354 * A system calls has to be restarted only if one of the error codes 355 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10 356 * isn't -1 then r8 doesn't hold an error code and we don't need to 357 * restart the syscall, so we can clear the "restart" flag here. 358 */ 359 restart = 0; 360 361 if (ksig.sig <= 0) 362 break; 363 364 if (unlikely(restart)) { 365 switch (errno) { 366 case ERESTART_RESTARTBLOCK: 367 case ERESTARTNOHAND: 368 scr->pt.r8 = EINTR; 369 /* note: scr->pt.r10 is already -1 */ 370 break; 371 case ERESTARTSYS: 372 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) { 373 scr->pt.r8 = EINTR; 374 /* note: scr->pt.r10 is already -1 */ 375 break; 376 } 377 fallthrough; 378 case ERESTARTNOINTR: 379 ia64_decrement_ip(&scr->pt); 380 restart = 0; /* don't restart twice if handle_signal() fails... */ 381 } 382 } 383 384 /* 385 * Whee! Actually deliver the signal. If the delivery failed, we need to 386 * continue to iterate in this loop so we can deliver the SIGSEGV... 387 */ 388 if (handle_signal(&ksig, scr)) 389 return; 390 } 391 392 /* Did we come from a system call? */ 393 if (restart) { 394 /* Restart the system call - no handlers present */ 395 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR 396 || errno == ERESTART_RESTARTBLOCK) 397 { 398 /* 399 * Note: the syscall number is in r15 which is saved in 400 * pt_regs so all we need to do here is adjust ip so that 401 * the "break" instruction gets re-executed. 402 */ 403 ia64_decrement_ip(&scr->pt); 404 if (errno == ERESTART_RESTARTBLOCK) 405 scr->pt.r15 = __NR_restart_syscall; 406 } 407 } 408 409 /* if there's no signal to deliver, we just put the saved sigmask 410 * back */ 411 restore_saved_sigmask(); 412 } 413