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