1 /* 2 * Copyright (C) 2013-2014 Altera Corporation 3 * Copyright (C) 2011-2012 Tobias Klauser <tklauser@distanz.ch> 4 * Copyright (C) 2004 Microtronix Datacom Ltd 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 * 7 * This file is subject to the terms and conditions of the GNU General Public 8 * License. See the file COPYING in the main directory of this archive 9 * for more details. 10 */ 11 12 #include <linux/signal.h> 13 #include <linux/errno.h> 14 #include <linux/ptrace.h> 15 #include <linux/uaccess.h> 16 #include <linux/unistd.h> 17 #include <linux/personality.h> 18 #include <linux/resume_user_mode.h> 19 20 #include <asm/ucontext.h> 21 #include <asm/cacheflush.h> 22 23 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 24 25 /* 26 * Do a signal return; undo the signal stack. 27 * 28 * Keep the return code on the stack quadword aligned! 29 * That makes the cache flush below easier. 30 */ 31 32 struct rt_sigframe { 33 struct siginfo info; 34 struct ucontext uc; 35 }; 36 37 static inline int rt_restore_ucontext(struct pt_regs *regs, 38 struct switch_stack *sw, 39 struct ucontext __user *uc, int *pr2) 40 { 41 int temp; 42 unsigned long __user *gregs = uc->uc_mcontext.gregs; 43 int err; 44 45 /* Always make any pending restarted system calls return -EINTR */ 46 current->restart_block.fn = do_no_restart_syscall; 47 48 err = __get_user(temp, &uc->uc_mcontext.version); 49 if (temp != MCONTEXT_VERSION) 50 goto badframe; 51 /* restore passed registers */ 52 err |= __get_user(regs->r1, &gregs[0]); 53 err |= __get_user(regs->r2, &gregs[1]); 54 err |= __get_user(regs->r3, &gregs[2]); 55 err |= __get_user(regs->r4, &gregs[3]); 56 err |= __get_user(regs->r5, &gregs[4]); 57 err |= __get_user(regs->r6, &gregs[5]); 58 err |= __get_user(regs->r7, &gregs[6]); 59 err |= __get_user(regs->r8, &gregs[7]); 60 err |= __get_user(regs->r9, &gregs[8]); 61 err |= __get_user(regs->r10, &gregs[9]); 62 err |= __get_user(regs->r11, &gregs[10]); 63 err |= __get_user(regs->r12, &gregs[11]); 64 err |= __get_user(regs->r13, &gregs[12]); 65 err |= __get_user(regs->r14, &gregs[13]); 66 err |= __get_user(regs->r15, &gregs[14]); 67 err |= __get_user(sw->r16, &gregs[15]); 68 err |= __get_user(sw->r17, &gregs[16]); 69 err |= __get_user(sw->r18, &gregs[17]); 70 err |= __get_user(sw->r19, &gregs[18]); 71 err |= __get_user(sw->r20, &gregs[19]); 72 err |= __get_user(sw->r21, &gregs[20]); 73 err |= __get_user(sw->r22, &gregs[21]); 74 err |= __get_user(sw->r23, &gregs[22]); 75 /* gregs[23] is handled below */ 76 err |= __get_user(sw->fp, &gregs[24]); /* Verify, should this be 77 settable */ 78 err |= __get_user(sw->gp, &gregs[25]); /* Verify, should this be 79 settable */ 80 81 err |= __get_user(temp, &gregs[26]); /* Not really necessary no user 82 settable bits */ 83 err |= __get_user(regs->ea, &gregs[27]); 84 85 err |= __get_user(regs->ra, &gregs[23]); 86 err |= __get_user(regs->sp, &gregs[28]); 87 88 regs->orig_r2 = -1; /* disable syscall checks */ 89 90 err |= restore_altstack(&uc->uc_stack); 91 if (err) 92 goto badframe; 93 94 *pr2 = regs->r2; 95 return err; 96 97 badframe: 98 return 1; 99 } 100 101 asmlinkage int do_rt_sigreturn(struct switch_stack *sw) 102 { 103 struct pt_regs *regs = (struct pt_regs *)(sw + 1); 104 /* Verify, can we follow the stack back */ 105 struct rt_sigframe __user *frame; 106 sigset_t set; 107 int rval; 108 109 frame = (struct rt_sigframe __user *) regs->sp; 110 if (!access_ok(frame, sizeof(*frame))) 111 goto badframe; 112 113 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 114 goto badframe; 115 116 set_current_blocked(&set); 117 118 if (rt_restore_ucontext(regs, sw, &frame->uc, &rval)) 119 goto badframe; 120 121 return rval; 122 123 badframe: 124 force_sig(SIGSEGV); 125 return 0; 126 } 127 128 static inline int rt_setup_ucontext(struct ucontext __user *uc, struct pt_regs *regs) 129 { 130 struct switch_stack *sw = (struct switch_stack *)regs - 1; 131 unsigned long __user *gregs = uc->uc_mcontext.gregs; 132 int err = 0; 133 134 err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version); 135 err |= __put_user(regs->r1, &gregs[0]); 136 err |= __put_user(regs->r2, &gregs[1]); 137 err |= __put_user(regs->r3, &gregs[2]); 138 err |= __put_user(regs->r4, &gregs[3]); 139 err |= __put_user(regs->r5, &gregs[4]); 140 err |= __put_user(regs->r6, &gregs[5]); 141 err |= __put_user(regs->r7, &gregs[6]); 142 err |= __put_user(regs->r8, &gregs[7]); 143 err |= __put_user(regs->r9, &gregs[8]); 144 err |= __put_user(regs->r10, &gregs[9]); 145 err |= __put_user(regs->r11, &gregs[10]); 146 err |= __put_user(regs->r12, &gregs[11]); 147 err |= __put_user(regs->r13, &gregs[12]); 148 err |= __put_user(regs->r14, &gregs[13]); 149 err |= __put_user(regs->r15, &gregs[14]); 150 err |= __put_user(sw->r16, &gregs[15]); 151 err |= __put_user(sw->r17, &gregs[16]); 152 err |= __put_user(sw->r18, &gregs[17]); 153 err |= __put_user(sw->r19, &gregs[18]); 154 err |= __put_user(sw->r20, &gregs[19]); 155 err |= __put_user(sw->r21, &gregs[20]); 156 err |= __put_user(sw->r22, &gregs[21]); 157 err |= __put_user(sw->r23, &gregs[22]); 158 err |= __put_user(regs->ra, &gregs[23]); 159 err |= __put_user(sw->fp, &gregs[24]); 160 err |= __put_user(sw->gp, &gregs[25]); 161 err |= __put_user(regs->ea, &gregs[27]); 162 err |= __put_user(regs->sp, &gregs[28]); 163 return err; 164 } 165 166 static inline void __user *get_sigframe(struct ksignal *ksig, 167 struct pt_regs *regs, 168 size_t frame_size) 169 { 170 unsigned long usp; 171 172 /* Default to using normal stack. */ 173 usp = regs->sp; 174 175 /* This is the X/Open sanctioned signal stack switching. */ 176 usp = sigsp(usp, ksig); 177 178 /* Verify, is it 32 or 64 bit aligned */ 179 return (void __user *)((usp - frame_size) & -8UL); 180 } 181 182 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 183 struct pt_regs *regs) 184 { 185 struct rt_sigframe __user *frame; 186 int err = 0; 187 188 frame = get_sigframe(ksig, regs, sizeof(*frame)); 189 190 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 191 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 192 193 /* Create the ucontext. */ 194 err |= __put_user(0, &frame->uc.uc_flags); 195 err |= __put_user(0, &frame->uc.uc_link); 196 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 197 err |= rt_setup_ucontext(&frame->uc, regs); 198 err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 199 200 if (err) 201 goto give_sigsegv; 202 203 /* Set up to return from userspace; jump to fixed address sigreturn 204 trampoline on kuser page. */ 205 regs->ra = (unsigned long) (0x1044); 206 207 /* Set up registers for signal handler */ 208 regs->sp = (unsigned long) frame; 209 regs->r4 = (unsigned long) ksig->sig; 210 regs->r5 = (unsigned long) &frame->info; 211 regs->r6 = (unsigned long) &frame->uc; 212 regs->ea = (unsigned long) ksig->ka.sa.sa_handler; 213 return 0; 214 215 give_sigsegv: 216 force_sigsegv(ksig->sig); 217 return -EFAULT; 218 } 219 220 /* 221 * OK, we're invoking a handler 222 */ 223 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 224 { 225 int ret; 226 sigset_t *oldset = sigmask_to_save(); 227 228 /* set up the stack frame */ 229 ret = setup_rt_frame(ksig, oldset, regs); 230 231 signal_setup_done(ret, ksig, 0); 232 } 233 234 static int do_signal(struct pt_regs *regs) 235 { 236 unsigned int retval = 0, continue_addr = 0, restart_addr = 0; 237 int restart = 0; 238 struct ksignal ksig; 239 240 current->thread.kregs = regs; 241 242 /* 243 * If we were from a system call, check for system call restarting... 244 */ 245 if (regs->orig_r2 >= 0) { 246 continue_addr = regs->ea; 247 restart_addr = continue_addr - 4; 248 retval = regs->r2; 249 250 /* 251 * Prepare for system call restart. We do this here so that a 252 * debugger will see the already changed PC. 253 */ 254 switch (retval) { 255 case ERESTART_RESTARTBLOCK: 256 restart = -2; 257 fallthrough; 258 case ERESTARTNOHAND: 259 case ERESTARTSYS: 260 case ERESTARTNOINTR: 261 restart++; 262 regs->r2 = regs->orig_r2; 263 regs->r7 = regs->orig_r7; 264 regs->ea = restart_addr; 265 break; 266 } 267 } 268 269 if (get_signal(&ksig)) { 270 /* handler */ 271 if (unlikely(restart && regs->ea == restart_addr)) { 272 if (retval == ERESTARTNOHAND || 273 retval == ERESTART_RESTARTBLOCK || 274 (retval == ERESTARTSYS 275 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 276 regs->r2 = EINTR; 277 regs->r7 = 1; 278 regs->ea = continue_addr; 279 } 280 } 281 handle_signal(&ksig, regs); 282 return 0; 283 } 284 285 /* 286 * No handler present 287 */ 288 if (unlikely(restart) && regs->ea == restart_addr) { 289 regs->ea = continue_addr; 290 regs->r2 = __NR_restart_syscall; 291 } 292 293 /* 294 * If there's no signal to deliver, we just put the saved sigmask back. 295 */ 296 restore_saved_sigmask(); 297 298 return restart; 299 } 300 301 asmlinkage int do_notify_resume(struct pt_regs *regs) 302 { 303 /* 304 * We want the common case to go fast, which is why we may in certain 305 * cases get here from kernel mode. Just return without doing anything 306 * if so. 307 */ 308 if (!user_mode(regs)) 309 return 0; 310 311 if (test_thread_flag(TIF_SIGPENDING) || 312 test_thread_flag(TIF_NOTIFY_SIGNAL)) { 313 int restart = do_signal(regs); 314 315 if (unlikely(restart)) { 316 /* 317 * Restart without handlers. 318 * Deal with it without leaving 319 * the kernel space. 320 */ 321 return restart; 322 } 323 } else if (test_thread_flag(TIF_NOTIFY_RESUME)) 324 resume_user_mode_work(regs); 325 326 return 0; 327 } 328