1 /* 2 * Signal handling 3 * 4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu> 5 * Copyright (C) 2008-2009 PetaLogix 6 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au> 7 * Copyright (C) 2001 NEC Corporation 8 * Copyright (C) 2001 Miles Bader <miles@gnu.org> 9 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima 10 * Copyright (C) 1991,1992 Linus Torvalds 11 * 12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 13 * 14 * This file was was derived from the sh version, arch/sh/kernel/signal.c 15 * 16 * This file is subject to the terms and conditions of the GNU General 17 * Public License. See the file COPYING in the main directory of this 18 * archive for more details. 19 */ 20 21 #include <linux/sched.h> 22 #include <linux/mm.h> 23 #include <linux/smp.h> 24 #include <linux/kernel.h> 25 #include <linux/signal.h> 26 #include <linux/errno.h> 27 #include <linux/wait.h> 28 #include <linux/ptrace.h> 29 #include <linux/unistd.h> 30 #include <linux/stddef.h> 31 #include <linux/personality.h> 32 #include <linux/percpu.h> 33 #include <linux/linkage.h> 34 #include <linux/tracehook.h> 35 #include <asm/entry.h> 36 #include <asm/ucontext.h> 37 #include <linux/uaccess.h> 38 #include <asm/pgtable.h> 39 #include <asm/pgalloc.h> 40 #include <linux/syscalls.h> 41 #include <asm/cacheflush.h> 42 #include <asm/syscalls.h> 43 44 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 45 46 asmlinkage long 47 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 48 struct pt_regs *regs) 49 { 50 return do_sigaltstack(uss, uoss, regs->r1); 51 } 52 53 /* 54 * Do a signal return; undo the signal stack. 55 */ 56 struct sigframe { 57 struct sigcontext sc; 58 unsigned long extramask[_NSIG_WORDS-1]; 59 unsigned long tramp[2]; /* signal trampoline */ 60 }; 61 62 struct rt_sigframe { 63 struct siginfo info; 64 struct ucontext uc; 65 unsigned long tramp[2]; /* signal trampoline */ 66 }; 67 68 static int restore_sigcontext(struct pt_regs *regs, 69 struct sigcontext __user *sc, int *rval_p) 70 { 71 unsigned int err = 0; 72 73 #define COPY(x) {err |= __get_user(regs->x, &sc->regs.x); } 74 COPY(r0); 75 COPY(r1); 76 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 77 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 78 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 79 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 80 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 81 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 82 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 83 COPY(r30); COPY(r31); 84 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 85 #undef COPY 86 87 *rval_p = regs->r3; 88 89 return err; 90 } 91 92 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 93 { 94 struct rt_sigframe __user *frame = 95 (struct rt_sigframe __user *)(regs->r1); 96 97 sigset_t set; 98 int rval; 99 100 /* Always make any pending restarted system calls return -EINTR */ 101 current_thread_info()->restart_block.fn = do_no_restart_syscall; 102 103 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 104 goto badframe; 105 106 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 107 goto badframe; 108 109 sigdelsetmask(&set, ~_BLOCKABLE); 110 set_current_blocked(&set); 111 112 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval)) 113 goto badframe; 114 115 /* It is more difficult to avoid calling this function than to 116 call it and ignore errors. */ 117 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1)) 118 goto badframe; 119 120 return rval; 121 122 badframe: 123 force_sig(SIGSEGV, current); 124 return 0; 125 } 126 127 /* 128 * Set up a signal frame. 129 */ 130 131 static int 132 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 133 unsigned long mask) 134 { 135 int err = 0; 136 137 #define COPY(x) {err |= __put_user(regs->x, &sc->regs.x); } 138 COPY(r0); 139 COPY(r1); 140 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 141 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 142 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 143 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 144 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 145 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 146 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 147 COPY(r30); COPY(r31); 148 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 149 #undef COPY 150 151 err |= __put_user(mask, &sc->oldmask); 152 153 return err; 154 } 155 156 /* 157 * Determine which stack to use.. 158 */ 159 static inline void __user * 160 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size) 161 { 162 /* Default to using normal stack */ 163 unsigned long sp = regs->r1; 164 165 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp)) 166 sp = current->sas_ss_sp + current->sas_ss_size; 167 168 return (void __user *)((sp - frame_size) & -8UL); 169 } 170 171 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 172 sigset_t *set, struct pt_regs *regs) 173 { 174 struct rt_sigframe __user *frame; 175 int err = 0; 176 int signal; 177 unsigned long address = 0; 178 #ifdef CONFIG_MMU 179 pmd_t *pmdp; 180 pte_t *ptep; 181 #endif 182 183 frame = get_sigframe(ka, regs, sizeof(*frame)); 184 185 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 186 goto give_sigsegv; 187 188 signal = current_thread_info()->exec_domain 189 && current_thread_info()->exec_domain->signal_invmap 190 && sig < 32 191 ? current_thread_info()->exec_domain->signal_invmap[sig] 192 : sig; 193 194 if (info) 195 err |= copy_siginfo_to_user(&frame->info, info); 196 197 /* Create the ucontext. */ 198 err |= __put_user(0, &frame->uc.uc_flags); 199 err |= __put_user(NULL, &frame->uc.uc_link); 200 err |= __put_user((void __user *)current->sas_ss_sp, 201 &frame->uc.uc_stack.ss_sp); 202 err |= __put_user(sas_ss_flags(regs->r1), 203 &frame->uc.uc_stack.ss_flags); 204 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 205 err |= setup_sigcontext(&frame->uc.uc_mcontext, 206 regs, set->sig[0]); 207 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 208 209 /* Set up to return from userspace. If provided, use a stub 210 already in userspace. */ 211 /* minus 8 is offset to cater for "rtsd r15,8" */ 212 /* addi r12, r0, __NR_sigreturn */ 213 err |= __put_user(0x31800000 | __NR_rt_sigreturn , 214 frame->tramp + 0); 215 /* brki r14, 0x8 */ 216 err |= __put_user(0xb9cc0008, frame->tramp + 1); 217 218 /* Return from sighandler will jump to the tramp. 219 Negative 8 offset because return is rtsd r15, 8 */ 220 regs->r15 = ((unsigned long)frame->tramp)-8; 221 222 address = ((unsigned long)frame->tramp); 223 #ifdef CONFIG_MMU 224 pmdp = pmd_offset(pud_offset( 225 pgd_offset(current->mm, address), 226 address), address); 227 228 preempt_disable(); 229 ptep = pte_offset_map(pmdp, address); 230 if (pte_present(*ptep)) { 231 address = (unsigned long) page_address(pte_page(*ptep)); 232 /* MS: I need add offset in page */ 233 address += ((unsigned long)frame->tramp) & ~PAGE_MASK; 234 /* MS address is virtual */ 235 address = virt_to_phys(address); 236 invalidate_icache_range(address, address + 8); 237 flush_dcache_range(address, address + 8); 238 } 239 pte_unmap(ptep); 240 preempt_enable(); 241 #else 242 flush_icache_range(address, address + 8); 243 flush_dcache_range(address, address + 8); 244 #endif 245 if (err) 246 goto give_sigsegv; 247 248 /* Set up registers for signal handler */ 249 regs->r1 = (unsigned long) frame; 250 251 /* Signal handler args: */ 252 regs->r5 = signal; /* arg 0: signum */ 253 regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */ 254 regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */ 255 /* Offset to handle microblaze rtid r14, 0 */ 256 regs->pc = (unsigned long)ka->sa.sa_handler; 257 258 set_fs(USER_DS); 259 260 /* the tracer may want to single-step inside the handler */ 261 if (test_thread_flag(TIF_SINGLESTEP)) 262 ptrace_notify(SIGTRAP); 263 264 #ifdef DEBUG_SIG 265 printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n", 266 current->comm, current->pid, frame, regs->pc); 267 #endif 268 269 return 0; 270 271 give_sigsegv: 272 force_sigsegv(sig, current); 273 return -EFAULT; 274 } 275 276 /* Handle restarting system calls */ 277 static inline void 278 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler) 279 { 280 switch (regs->r3) { 281 case -ERESTART_RESTARTBLOCK: 282 case -ERESTARTNOHAND: 283 if (!has_handler) 284 goto do_restart; 285 regs->r3 = -EINTR; 286 break; 287 case -ERESTARTSYS: 288 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) { 289 regs->r3 = -EINTR; 290 break; 291 } 292 /* fallthrough */ 293 case -ERESTARTNOINTR: 294 do_restart: 295 /* offset of 4 bytes to re-execute trap (brki) instruction */ 296 #ifndef CONFIG_MMU 297 regs->pc -= 4; 298 #else 299 /* offset of 8 bytes required = 4 for rtbd 300 offset, plus 4 for size of 301 "brki r14,8" 302 instruction. */ 303 regs->pc -= 8; 304 #endif 305 break; 306 } 307 } 308 309 /* 310 * OK, we're invoking a handler 311 */ 312 313 static int 314 handle_signal(unsigned long sig, struct k_sigaction *ka, 315 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 316 { 317 int ret; 318 319 /* Set up the stack frame */ 320 if (ka->sa.sa_flags & SA_SIGINFO) 321 ret = setup_rt_frame(sig, ka, info, oldset, regs); 322 else 323 ret = setup_rt_frame(sig, ka, NULL, oldset, regs); 324 325 if (ret) 326 return ret; 327 328 block_sigmask(ka, sig); 329 330 return 0; 331 } 332 333 /* 334 * Note that 'init' is a special process: it doesn't get signals it doesn't 335 * want to handle. Thus you cannot kill init even with a SIGKILL even by 336 * mistake. 337 * 338 * Note that we go through the signals twice: once to check the signals that 339 * the kernel can handle, and then we build all the user-level signal handling 340 * stack-frames in one go after that. 341 */ 342 static void do_signal(struct pt_regs *regs, int in_syscall) 343 { 344 siginfo_t info; 345 int signr; 346 struct k_sigaction ka; 347 sigset_t *oldset; 348 #ifdef DEBUG_SIG 349 printk(KERN_INFO "do signal: %p %d\n", regs, in_syscall); 350 printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1, 351 regs->r12, current_thread_info()->flags); 352 #endif 353 354 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 355 oldset = ¤t->saved_sigmask; 356 else 357 oldset = ¤t->blocked; 358 359 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 360 if (signr > 0) { 361 /* Whee! Actually deliver the signal. */ 362 if (in_syscall) 363 handle_restart(regs, &ka, 1); 364 if (!handle_signal(signr, &ka, &info, oldset, regs)) { 365 /* 366 * A signal was successfully delivered; the saved 367 * sigmask will have been stored in the signal frame, 368 * and will be restored by sigreturn, so we can simply 369 * clear the TS_RESTORE_SIGMASK flag. 370 */ 371 current_thread_info()->status &= 372 ~TS_RESTORE_SIGMASK; 373 } 374 return; 375 } 376 377 if (in_syscall) 378 handle_restart(regs, NULL, 0); 379 380 /* 381 * If there's no signal to deliver, we just put the saved sigmask 382 * back. 383 */ 384 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 385 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 386 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 387 } 388 } 389 390 void do_notify_resume(struct pt_regs *regs, int in_syscall) 391 { 392 /* 393 * We want the common case to go fast, which 394 * is why we may in certain cases get here from 395 * kernel mode. Just return without doing anything 396 * if so. 397 */ 398 if (kernel_mode(regs)) 399 return; 400 401 if (test_thread_flag(TIF_SIGPENDING)) 402 do_signal(regs, in_syscall); 403 404 if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) { 405 tracehook_notify_resume(regs); 406 if (current->replacement_session_keyring) 407 key_replace_session_keyring(); 408 } 409 } 410