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 stack_t st; 88 89 /* 90 * Since we stacked the signal on a dword boundary, 91 * then frame should be dword aligned here. If it's 92 * not, then the user is trying to mess with us. 93 */ 94 if (((long)frame) & 3) 95 goto badframe; 96 97 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 98 goto badframe; 99 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 100 goto badframe; 101 102 set_current_blocked(&set); 103 104 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 105 goto badframe; 106 107 if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st))) 108 goto badframe; 109 /* It is more difficult to avoid calling this function than to 110 call it and ignore errors. */ 111 do_sigaltstack(&st, NULL, regs->sp); 112 113 return regs->gpr[11]; 114 115 badframe: 116 force_sig(SIGSEGV, current); 117 return 0; 118 } 119 120 /* 121 * Set up a signal frame. 122 */ 123 124 static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, 125 unsigned long mask) 126 { 127 int err = 0; 128 129 /* copy the regs */ 130 131 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); 132 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); 133 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); 134 135 /* then some other stuff */ 136 137 err |= __put_user(mask, &sc->oldmask); 138 139 return err; 140 } 141 142 static inline unsigned long align_sigframe(unsigned long sp) 143 { 144 return sp & ~3UL; 145 } 146 147 /* 148 * Work out where the signal frame should go. It's either on the user stack 149 * or the alternate stack. 150 */ 151 152 static inline void __user *get_sigframe(struct k_sigaction *ka, 153 struct pt_regs *regs, size_t frame_size) 154 { 155 unsigned long sp = regs->sp; 156 int onsigstack = on_sig_stack(sp); 157 158 /* redzone */ 159 sp -= STACK_FRAME_OVERHEAD; 160 161 /* This is the X/Open sanctioned signal stack switching. */ 162 if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { 163 if (current->sas_ss_size) 164 sp = current->sas_ss_sp + current->sas_ss_size; 165 } 166 167 sp = align_sigframe(sp - frame_size); 168 169 /* 170 * If we are on the alternate signal stack and would overflow it, don't. 171 * Return an always-bogus address instead so we will die with SIGSEGV. 172 */ 173 if (onsigstack && !likely(on_sig_stack(sp))) 174 return (void __user *)-1L; 175 176 return (void __user *)sp; 177 } 178 179 /* grab and setup a signal frame. 180 * 181 * basically we stack a lot of state info, and arrange for the 182 * user-mode program to return to the kernel using either a 183 * trampoline which performs the syscall sigreturn, or a provided 184 * user-mode trampoline. 185 */ 186 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 187 sigset_t *set, struct pt_regs *regs) 188 { 189 struct rt_sigframe *frame; 190 unsigned long return_ip; 191 int err = 0; 192 193 frame = get_sigframe(ka, regs, sizeof(*frame)); 194 195 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 196 goto give_sigsegv; 197 198 err |= __put_user(&frame->info, &frame->pinfo); 199 err |= __put_user(&frame->uc, &frame->puc); 200 201 if (ka->sa.sa_flags & SA_SIGINFO) 202 err |= copy_siginfo_to_user(&frame->info, info); 203 if (err) 204 goto give_sigsegv; 205 206 /* Clear all the bits of the ucontext we don't use. */ 207 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); 208 err |= __put_user(0, &frame->uc.uc_flags); 209 err |= __put_user(NULL, &frame->uc.uc_link); 210 err |= __put_user((void *)current->sas_ss_sp, 211 &frame->uc.uc_stack.ss_sp); 212 err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); 213 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 214 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); 215 216 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 217 218 if (err) 219 goto give_sigsegv; 220 221 /* trampoline - the desired return ip is the retcode itself */ 222 return_ip = (unsigned long)&frame->retcode; 223 /* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */ 224 err |= __put_user(0xa960, (short *)(frame->retcode + 0)); 225 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); 226 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); 227 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); 228 229 if (err) 230 goto give_sigsegv; 231 232 /* TODO what is the current->exec_domain stuff and invmap ? */ 233 234 /* Set up registers for signal handler */ 235 regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ 236 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ 237 regs->gpr[3] = (unsigned long)sig; /* arg 1: signo */ 238 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ 239 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ 240 241 /* actually move the usp to reflect the stacked frame */ 242 regs->sp = (unsigned long)frame; 243 244 return 0; 245 246 give_sigsegv: 247 force_sigsegv(sig, current); 248 return -EFAULT; 249 } 250 251 static inline void 252 handle_signal(unsigned long sig, 253 siginfo_t *info, struct k_sigaction *ka, 254 struct pt_regs *regs) 255 { 256 int ret; 257 258 ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs); 259 if (ret) 260 return; 261 262 signal_delivered(sig, info, ka, regs, 263 test_thread_flag(TIF_SINGLESTEP)); 264 } 265 266 /* 267 * Note that 'init' is a special process: it doesn't get signals it doesn't 268 * want to handle. Thus you cannot kill init even with a SIGKILL even by 269 * mistake. 270 * 271 * Also note that the regs structure given here as an argument, is the latest 272 * pushed pt_regs. It may or may not be the same as the first pushed registers 273 * when the initial usermode->kernelmode transition took place. Therefore 274 * we can use user_mode(regs) to see if we came directly from kernel or user 275 * mode below. 276 */ 277 278 void do_signal(struct pt_regs *regs) 279 { 280 siginfo_t info; 281 int signr; 282 struct k_sigaction ka; 283 284 /* 285 * We want the common case to go fast, which 286 * is why we may in certain cases get here from 287 * kernel mode. Just return without doing anything 288 * if so. 289 */ 290 if (!user_mode(regs)) 291 return; 292 293 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 294 295 /* If we are coming out of a syscall then we need 296 * to check if the syscall was interrupted and wants to be 297 * restarted after handling the signal. If so, the original 298 * syscall number is put back into r11 and the PC rewound to 299 * point at the l.sys instruction that resulted in the 300 * original syscall. Syscall results other than the four 301 * below mean that the syscall executed to completion and no 302 * restart is necessary. 303 */ 304 if (regs->orig_gpr11) { 305 int restart = 0; 306 307 switch (regs->gpr[11]) { 308 case -ERESTART_RESTARTBLOCK: 309 case -ERESTARTNOHAND: 310 /* Restart if there is no signal handler */ 311 restart = (signr <= 0); 312 break; 313 case -ERESTARTSYS: 314 /* Restart if there no signal handler or 315 * SA_RESTART flag is set */ 316 restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); 317 break; 318 case -ERESTARTNOINTR: 319 /* Always restart */ 320 restart = 1; 321 break; 322 } 323 324 if (restart) { 325 if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) 326 regs->gpr[11] = __NR_restart_syscall; 327 else 328 regs->gpr[11] = regs->orig_gpr11; 329 regs->pc -= 4; 330 } else { 331 regs->gpr[11] = -EINTR; 332 } 333 } 334 335 if (signr <= 0) { 336 /* no signal to deliver so we just put the saved sigmask 337 * back */ 338 restore_saved_sigmask(); 339 } else { /* signr > 0 */ 340 /* Whee! Actually deliver the signal. */ 341 handle_signal(signr, &info, &ka, regs); 342 } 343 344 return; 345 } 346 347 asmlinkage void do_notify_resume(struct pt_regs *regs) 348 { 349 if (current_thread_info()->flags & _TIF_SIGPENDING) 350 do_signal(regs); 351 352 if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { 353 clear_thread_flag(TIF_NOTIFY_RESUME); 354 tracehook_notify_resume(regs); 355 } 356 } 357