1 /* 2 * OpenRISC signal.c 3 * 4 * Linux architectural port borrowing liberally from similar works of 5 * others. All original copyrights apply as per the original source 6 * declaration. 7 * 8 * Modifications for the OpenRISC architecture: 9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 11 * 12 * This program is free software; you can redistribute it and/or 13 * modify it under the terms of the GNU General Public License 14 * as published by the Free Software Foundation; either version 15 * 2 of the License, or (at your option) any later version. 16 */ 17 18 #include <linux/sched.h> 19 #include <linux/mm.h> 20 #include <linux/smp.h> 21 #include <linux/kernel.h> 22 #include <linux/signal.h> 23 #include <linux/errno.h> 24 #include <linux/wait.h> 25 #include <linux/ptrace.h> 26 #include <linux/unistd.h> 27 #include <linux/stddef.h> 28 #include <linux/tracehook.h> 29 30 #include <asm/processor.h> 31 #include <asm/ucontext.h> 32 #include <asm/uaccess.h> 33 34 #define DEBUG_SIG 0 35 36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 37 38 asmlinkage long 39 _sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs) 40 { 41 return do_sigaltstack(uss, uoss, regs->sp); 42 } 43 44 struct rt_sigframe { 45 struct siginfo *pinfo; 46 void *puc; 47 struct siginfo info; 48 struct ucontext uc; 49 unsigned char retcode[16]; /* trampoline code */ 50 }; 51 52 static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc) 53 { 54 unsigned int err = 0; 55 unsigned long old_usp; 56 57 /* Alwys make any pending restarted system call return -EINTR */ 58 current_thread_info()->restart_block.fn = do_no_restart_syscall; 59 60 /* restore the regs from &sc->regs (same as sc, since regs is first) 61 * (sc is already checked for VERIFY_READ since the sigframe was 62 * checked in sys_sigreturn previously) 63 */ 64 65 if (__copy_from_user(regs, sc, sizeof(struct pt_regs))) 66 goto badframe; 67 68 /* make sure the SM-bit is cleared so user-mode cannot fool us */ 69 regs->sr &= ~SPR_SR_SM; 70 71 /* restore the old USP as it was before we stacked the sc etc. 72 * (we cannot just pop the sigcontext since we aligned the sp and 73 * stuff after pushing it) 74 */ 75 76 err |= __get_user(old_usp, &sc->usp); 77 78 regs->sp = old_usp; 79 80 /* TODO: the other ports use regs->orig_XX to disable syscall checks 81 * after this completes, but we don't use that mechanism. maybe we can 82 * use it now ? 83 */ 84 85 return err; 86 87 badframe: 88 return 1; 89 } 90 91 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) 92 { 93 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; 94 sigset_t set; 95 stack_t st; 96 97 /* 98 * Since we stacked the signal on a dword boundary, 99 * then frame should be dword aligned here. If it's 100 * not, then the user is trying to mess with us. 101 */ 102 if (((long)frame) & 3) 103 goto badframe; 104 105 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 106 goto badframe; 107 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 108 goto badframe; 109 110 sigdelsetmask(&set, ~_BLOCKABLE); 111 spin_lock_irq(¤t->sighand->siglock); 112 current->blocked = set; 113 recalc_sigpending(); 114 spin_unlock_irq(¤t->sighand->siglock); 115 116 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 117 goto badframe; 118 119 if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st))) 120 goto badframe; 121 /* It is more difficult to avoid calling this function than to 122 call it and ignore errors. */ 123 do_sigaltstack(&st, NULL, regs->sp); 124 125 return regs->gpr[11]; 126 127 badframe: 128 force_sig(SIGSEGV, current); 129 return 0; 130 } 131 132 /* 133 * Set up a signal frame. 134 */ 135 136 static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, 137 unsigned long mask) 138 { 139 int err = 0; 140 unsigned long usp = regs->sp; 141 142 /* copy the regs. they are first in sc so we can use sc directly */ 143 144 err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); 145 146 /* then some other stuff */ 147 148 err |= __put_user(mask, &sc->oldmask); 149 150 err |= __put_user(usp, &sc->usp); 151 152 return err; 153 } 154 155 static inline unsigned long align_sigframe(unsigned long sp) 156 { 157 return sp & ~3UL; 158 } 159 160 /* 161 * Work out where the signal frame should go. It's either on the user stack 162 * or the alternate stack. 163 */ 164 165 static inline void __user *get_sigframe(struct k_sigaction *ka, 166 struct pt_regs *regs, size_t frame_size) 167 { 168 unsigned long sp = regs->sp; 169 int onsigstack = on_sig_stack(sp); 170 171 /* redzone */ 172 sp -= STACK_FRAME_OVERHEAD; 173 174 /* This is the X/Open sanctioned signal stack switching. */ 175 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { 176 if (current->sas_ss_size) 177 sp = current->sas_ss_sp + current->sas_ss_size; 178 } 179 180 sp = align_sigframe(sp - frame_size); 181 182 /* 183 * If we are on the alternate signal stack and would overflow it, don't. 184 * Return an always-bogus address instead so we will die with SIGSEGV. 185 */ 186 if (onsigstack && !likely(on_sig_stack(sp))) 187 return (void __user *)-1L; 188 189 return (void __user *)sp; 190 } 191 192 /* grab and setup a signal frame. 193 * 194 * basically we stack a lot of state info, and arrange for the 195 * user-mode program to return to the kernel using either a 196 * trampoline which performs the syscall sigreturn, or a provided 197 * user-mode trampoline. 198 */ 199 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 200 sigset_t *set, struct pt_regs *regs) 201 { 202 struct rt_sigframe *frame; 203 unsigned long return_ip; 204 int err = 0; 205 206 frame = get_sigframe(ka, regs, sizeof(*frame)); 207 208 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 209 goto give_sigsegv; 210 211 err |= __put_user(&frame->info, &frame->pinfo); 212 err |= __put_user(&frame->uc, &frame->puc); 213 214 if (ka->sa.sa_flags & SA_SIGINFO) 215 err |= copy_siginfo_to_user(&frame->info, info); 216 if (err) 217 goto give_sigsegv; 218 219 /* Clear all the bits of the ucontext we don't use. */ 220 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); 221 err |= __put_user(0, &frame->uc.uc_flags); 222 err |= __put_user(NULL, &frame->uc.uc_link); 223 err |= __put_user((void *)current->sas_ss_sp, 224 &frame->uc.uc_stack.ss_sp); 225 err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); 226 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 227 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); 228 229 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 230 231 if (err) 232 goto give_sigsegv; 233 234 /* trampoline - the desired return ip is the retcode itself */ 235 return_ip = (unsigned long)&frame->retcode; 236 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */ 237 err |= __put_user(0xa960, (short *)(frame->retcode + 0)); 238 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); 239 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); 240 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); 241 242 if (err) 243 goto give_sigsegv; 244 245 /* TODO what is the current->exec_domain stuff and invmap ? */ 246 247 /* Set up registers for signal handler */ 248 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ 249 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ 250 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */ 251 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ 252 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ 253 254 /* actually move the usp to reflect the stacked frame */ 255 regs->sp = (unsigned long)frame; 256 257 return; 258 259 give_sigsegv: 260 if (sig == SIGSEGV) 261 ka->sa.sa_handler = SIG_DFL; 262 force_sig(SIGSEGV, current); 263 } 264 265 static inline void 266 handle_signal(unsigned long sig, 267 siginfo_t *info, struct k_sigaction *ka, 268 sigset_t *oldset, struct pt_regs *regs) 269 { 270 setup_rt_frame(sig, ka, info, oldset, regs); 271 272 if (ka->sa.sa_flags & SA_ONESHOT) 273 ka->sa.sa_handler = SIG_DFL; 274 275 spin_lock_irq(¤t->sighand->siglock); 276 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 277 if (!(ka->sa.sa_flags & SA_NODEFER)) 278 sigaddset(¤t->blocked, sig); 279 recalc_sigpending(); 280 281 spin_unlock_irq(¤t->sighand->siglock); 282 } 283 284 /* 285 * Note that 'init' is a special process: it doesn't get signals it doesn't 286 * want to handle. Thus you cannot kill init even with a SIGKILL even by 287 * mistake. 288 * 289 * Also note that the regs structure given here as an argument, is the latest 290 * pushed pt_regs. It may or may not be the same as the first pushed registers 291 * when the initial usermode->kernelmode transition took place. Therefore 292 * we can use user_mode(regs) to see if we came directly from kernel or user 293 * mode below. 294 */ 295 296 void do_signal(struct pt_regs *regs) 297 { 298 siginfo_t info; 299 int signr; 300 struct k_sigaction ka; 301 302 /* 303 * We want the common case to go fast, which 304 * is why we may in certain cases get here from 305 * kernel mode. Just return without doing anything 306 * if so. 307 */ 308 if (!user_mode(regs)) 309 return; 310 311 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 312 313 /* If we are coming out of a syscall then we need 314 * to check if the syscall was interrupted and wants to be 315 * restarted after handling the signal. If so, the original 316 * syscall number is put back into r11 and the PC rewound to 317 * point at the l.sys instruction that resulted in the 318 * original syscall. Syscall results other than the four 319 * below mean that the syscall executed to completion and no 320 * restart is necessary. 321 */ 322 if (regs->syscallno) { 323 int restart = 0; 324 325 switch (regs->gpr[11]) { 326 case -ERESTART_RESTARTBLOCK: 327 case -ERESTARTNOHAND: 328 /* Restart if there is no signal handler */ 329 restart = (signr <= 0); 330 break; 331 case -ERESTARTSYS: 332 /* Restart if there no signal handler or 333 * SA_RESTART flag is set */ 334 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); 335 break; 336 case -ERESTARTNOINTR: 337 /* Always restart */ 338 restart = 1; 339 break; 340 } 341 342 if (restart) { 343 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) 344 regs->gpr[11] = __NR_restart_syscall; 345 else 346 regs->gpr[11] = regs->orig_gpr11; 347 regs->pc -= 4; 348 } else { 349 regs->gpr[11] = -EINTR; 350 } 351 } 352 353 if (signr <= 0) { 354 /* no signal to deliver so we just put the saved sigmask 355 * back */ 356 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 357 clear_thread_flag(TIF_RESTORE_SIGMASK); 358 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 359 } 360 361 } else { /* signr > 0 */ 362 sigset_t *oldset; 363 364 if (current_thread_info()->flags & _TIF_RESTORE_SIGMASK) 365 oldset = ¤t->saved_sigmask; 366 else 367 oldset = ¤t->blocked; 368 369 /* Whee! Actually deliver the signal. */ 370 handle_signal(signr, &info, &ka, oldset, regs); 371 /* a signal was successfully delivered; the saved 372 * sigmask will have been stored in the signal frame, 373 * and will be restored by sigreturn, so we can simply 374 * clear the TIF_RESTORE_SIGMASK flag */ 375 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 376 clear_thread_flag(TIF_RESTORE_SIGMASK); 377 378 tracehook_signal_handler(signr, &info, &ka, regs, 379 test_thread_flag(TIF_SINGLESTEP)); 380 } 381 382 return; 383 } 384 385 asmlinkage void do_notify_resume(struct pt_regs *regs) 386 { 387 if (current_thread_info()->flags & _TIF_SIGPENDING) 388 do_signal(regs); 389 390 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { 391 clear_thread_flag(TIF_NOTIFY_RESUME); 392 tracehook_notify_resume(regs); 393 if (current->replacement_session_keyring) 394 key_replace_session_keyring(); 395 } 396 } 397