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 asmlinkage long 37 _sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs) 38 { 39 return do_sigaltstack(uss, uoss, regs->sp); 40 } 41 42 struct rt_sigframe { 43 struct siginfo *pinfo; 44 void *puc; 45 struct siginfo info; 46 struct ucontext uc; 47 unsigned char retcode[16]; /* trampoline code */ 48 }; 49 50 static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc) 51 { 52 unsigned int err = 0; 53 54 /* Alwys make any pending restarted system call return -EINTR */ 55 current_thread_info()->restart_block.fn = do_no_restart_syscall; 56 57 /* 58 * Restore the regs from &sc->regs. 59 * (sc is already checked for VERIFY_READ since the sigframe was 60 * checked in sys_sigreturn previously) 61 */ 62 if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long))) 63 goto badframe; 64 if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long))) 65 goto badframe; 66 if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long))) 67 goto badframe; 68 69 /* make sure the SM-bit is cleared so user-mode cannot fool us */ 70 regs->sr &= ~SPR_SR_SM; 71 72 /* TODO: the other ports use regs->orig_XX to disable syscall checks 73 * after this completes, but we don't use that mechanism. maybe we can 74 * use it now ? 75 */ 76 77 return err; 78 79 badframe: 80 return 1; 81 } 82 83 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) 84 { 85 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; 86 sigset_t set; 87 88 /* 89 * Since we stacked the signal on a dword boundary, 90 * then frame should be dword aligned here. If it's 91 * not, then the user is trying to mess with us. 92 */ 93 if (((long)frame) & 3) 94 goto badframe; 95 96 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 97 goto badframe; 98 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 99 goto badframe; 100 101 set_current_blocked(&set); 102 103 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 104 goto badframe; 105 106 /* It is more difficult to avoid calling this function than to 107 call it and ignore errors. */ 108 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 109 goto badframe; 110 111 return regs->gpr[11]; 112 113 badframe: 114 force_sig(SIGSEGV, current); 115 return 0; 116 } 117 118 /* 119 * Set up a signal frame. 120 */ 121 122 static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, 123 unsigned long mask) 124 { 125 int err = 0; 126 127 /* copy the regs */ 128 129 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); 130 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); 131 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); 132 133 /* then some other stuff */ 134 135 err |= __put_user(mask, &sc->oldmask); 136 137 return err; 138 } 139 140 static inline unsigned long align_sigframe(unsigned long sp) 141 { 142 return sp & ~3UL; 143 } 144 145 /* 146 * Work out where the signal frame should go. It's either on the user stack 147 * or the alternate stack. 148 */ 149 150 static inline void __user *get_sigframe(struct k_sigaction *ka, 151 struct pt_regs *regs, size_t frame_size) 152 { 153 unsigned long sp = regs->sp; 154 int onsigstack = on_sig_stack(sp); 155 156 /* redzone */ 157 sp -= STACK_FRAME_OVERHEAD; 158 159 /* This is the X/Open sanctioned signal stack switching. */ 160 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { 161 if (current->sas_ss_size) 162 sp = current->sas_ss_sp + current->sas_ss_size; 163 } 164 165 sp = align_sigframe(sp - frame_size); 166 167 /* 168 * If we are on the alternate signal stack and would overflow it, don't. 169 * Return an always-bogus address instead so we will die with SIGSEGV. 170 */ 171 if (onsigstack && !likely(on_sig_stack(sp))) 172 return (void __user *)-1L; 173 174 return (void __user *)sp; 175 } 176 177 /* grab and setup a signal frame. 178 * 179 * basically we stack a lot of state info, and arrange for the 180 * user-mode program to return to the kernel using either a 181 * trampoline which performs the syscall sigreturn, or a provided 182 * user-mode trampoline. 183 */ 184 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 185 sigset_t *set, struct pt_regs *regs) 186 { 187 struct rt_sigframe *frame; 188 unsigned long return_ip; 189 int err = 0; 190 191 frame = get_sigframe(ka, regs, sizeof(*frame)); 192 193 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 194 goto give_sigsegv; 195 196 err |= __put_user(&frame->info, &frame->pinfo); 197 err |= __put_user(&frame->uc, &frame->puc); 198 199 if (ka->sa.sa_flags & SA_SIGINFO) 200 err |= copy_siginfo_to_user(&frame->info, info); 201 if (err) 202 goto give_sigsegv; 203 204 /* Clear all the bits of the ucontext we don't use. */ 205 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); 206 err |= __put_user(0, &frame->uc.uc_flags); 207 err |= __put_user(NULL, &frame->uc.uc_link); 208 err |= __put_user((void *)current->sas_ss_sp, 209 &frame->uc.uc_stack.ss_sp); 210 err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); 211 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 212 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); 213 214 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 215 216 if (err) 217 goto give_sigsegv; 218 219 /* trampoline - the desired return ip is the retcode itself */ 220 return_ip = (unsigned long)&frame->retcode; 221 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */ 222 err |= __put_user(0xa960, (short *)(frame->retcode + 0)); 223 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); 224 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); 225 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); 226 227 if (err) 228 goto give_sigsegv; 229 230 /* TODO what is the current->exec_domain stuff and invmap ? */ 231 232 /* Set up registers for signal handler */ 233 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ 234 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ 235 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */ 236 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ 237 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ 238 239 /* actually move the usp to reflect the stacked frame */ 240 regs->sp = (unsigned long)frame; 241 242 return 0; 243 244 give_sigsegv: 245 force_sigsegv(sig, current); 246 return -EFAULT; 247 } 248 249 static inline void 250 handle_signal(unsigned long sig, 251 siginfo_t *info, struct k_sigaction *ka, 252 struct pt_regs *regs) 253 { 254 int ret; 255 256 ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs); 257 if (ret) 258 return; 259 260 signal_delivered(sig, info, ka, regs, 261 test_thread_flag(TIF_SINGLESTEP)); 262 } 263 264 /* 265 * Note that 'init' is a special process: it doesn't get signals it doesn't 266 * want to handle. Thus you cannot kill init even with a SIGKILL even by 267 * mistake. 268 * 269 * Also note that the regs structure given here as an argument, is the latest 270 * pushed pt_regs. It may or may not be the same as the first pushed registers 271 * when the initial usermode->kernelmode transition took place. Therefore 272 * we can use user_mode(regs) to see if we came directly from kernel or user 273 * mode below. 274 */ 275 276 void do_signal(struct pt_regs *regs) 277 { 278 siginfo_t info; 279 int signr; 280 struct k_sigaction ka; 281 282 /* 283 * We want the common case to go fast, which 284 * is why we may in certain cases get here from 285 * kernel mode. Just return without doing anything 286 * if so. 287 */ 288 if (!user_mode(regs)) 289 return; 290 291 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 292 293 /* If we are coming out of a syscall then we need 294 * to check if the syscall was interrupted and wants to be 295 * restarted after handling the signal. If so, the original 296 * syscall number is put back into r11 and the PC rewound to 297 * point at the l.sys instruction that resulted in the 298 * original syscall. Syscall results other than the four 299 * below mean that the syscall executed to completion and no 300 * restart is necessary. 301 */ 302 if (regs->orig_gpr11) { 303 int restart = 0; 304 305 switch (regs->gpr[11]) { 306 case -ERESTART_RESTARTBLOCK: 307 case -ERESTARTNOHAND: 308 /* Restart if there is no signal handler */ 309 restart = (signr <= 0); 310 break; 311 case -ERESTARTSYS: 312 /* Restart if there no signal handler or 313 * SA_RESTART flag is set */ 314 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); 315 break; 316 case -ERESTARTNOINTR: 317 /* Always restart */ 318 restart = 1; 319 break; 320 } 321 322 if (restart) { 323 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) 324 regs->gpr[11] = __NR_restart_syscall; 325 else 326 regs->gpr[11] = regs->orig_gpr11; 327 regs->pc -= 4; 328 } else { 329 regs->gpr[11] = -EINTR; 330 } 331 } 332 333 if (signr <= 0) { 334 /* no signal to deliver so we just put the saved sigmask 335 * back */ 336 restore_saved_sigmask(); 337 } else { /* signr > 0 */ 338 /* Whee! Actually deliver the signal. */ 339 handle_signal(signr, &info, &ka, regs); 340 } 341 342 return; 343 } 344 345 asmlinkage void do_notify_resume(struct pt_regs *regs) 346 { 347 if (current_thread_info()->flags & _TIF_SIGPENDING) 348 do_signal(regs); 349 350 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { 351 clear_thread_flag(TIF_NOTIFY_RESUME); 352 tracehook_notify_resume(regs); 353 } 354 } 355