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/syscall.h> 32 #include <asm/ucontext.h> 33 #include <linux/uaccess.h> 34 35 #define DEBUG_SIG 0 36 37 struct rt_sigframe { 38 struct siginfo info; 39 struct ucontext uc; 40 unsigned char retcode[16]; /* trampoline code */ 41 }; 42 43 static int restore_sigcontext(struct pt_regs *regs, 44 struct sigcontext __user *sc) 45 { 46 int err = 0; 47 48 /* Always make any pending restarted system calls return -EINTR */ 49 current->restart_block.fn = do_no_restart_syscall; 50 51 /* 52 * Restore the regs from &sc->regs. 53 * (sc is already checked since the sigframe was 54 * checked in sys_sigreturn previously) 55 */ 56 err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)); 57 err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)); 58 err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)); 59 60 /* make sure the SM-bit is cleared so user-mode cannot fool us */ 61 regs->sr &= ~SPR_SR_SM; 62 63 regs->orig_gpr11 = -1; /* Avoid syscall restart checks */ 64 65 /* TODO: the other ports use regs->orig_XX to disable syscall checks 66 * after this completes, but we don't use that mechanism. maybe we can 67 * use it now ? 68 */ 69 70 return err; 71 } 72 73 asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) 74 { 75 struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; 76 sigset_t set; 77 78 /* 79 * Since we stacked the signal on a dword boundary, 80 * then frame should be dword aligned here. If it's 81 * not, then the user is trying to mess with us. 82 */ 83 if (((long)frame) & 3) 84 goto badframe; 85 86 if (!access_ok(frame, sizeof(*frame))) 87 goto badframe; 88 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 89 goto badframe; 90 91 set_current_blocked(&set); 92 93 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 94 goto badframe; 95 96 if (restore_altstack(&frame->uc.uc_stack)) 97 goto badframe; 98 99 return regs->gpr[11]; 100 101 badframe: 102 force_sig(SIGSEGV, current); 103 return 0; 104 } 105 106 /* 107 * Set up a signal frame. 108 */ 109 110 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 111 { 112 int err = 0; 113 114 /* copy the regs */ 115 /* There should be no need to save callee-saved registers here... 116 * ...but we save them anyway. Revisit this 117 */ 118 err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); 119 err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); 120 err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); 121 122 return err; 123 } 124 125 static inline unsigned long align_sigframe(unsigned long sp) 126 { 127 return sp & ~3UL; 128 } 129 130 /* 131 * Work out where the signal frame should go. It's either on the user stack 132 * or the alternate stack. 133 */ 134 135 static inline void __user *get_sigframe(struct ksignal *ksig, 136 struct pt_regs *regs, size_t frame_size) 137 { 138 unsigned long sp = regs->sp; 139 140 /* redzone */ 141 sp -= STACK_FRAME_OVERHEAD; 142 sp = sigsp(sp, ksig); 143 sp = align_sigframe(sp - frame_size); 144 145 return (void __user *)sp; 146 } 147 148 /* grab and setup a signal frame. 149 * 150 * basically we stack a lot of state info, and arrange for the 151 * user-mode program to return to the kernel using either a 152 * trampoline which performs the syscall sigreturn, or a provided 153 * user-mode trampoline. 154 */ 155 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 156 struct pt_regs *regs) 157 { 158 struct rt_sigframe *frame; 159 unsigned long return_ip; 160 int err = 0; 161 162 frame = get_sigframe(ksig, regs, sizeof(*frame)); 163 164 if (!access_ok(frame, sizeof(*frame))) 165 return -EFAULT; 166 167 /* Create siginfo. */ 168 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 169 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 170 171 /* Create the ucontext. */ 172 err |= __put_user(0, &frame->uc.uc_flags); 173 err |= __put_user(NULL, &frame->uc.uc_link); 174 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 175 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext); 176 177 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 178 179 if (err) 180 return -EFAULT; 181 182 /* trampoline - the desired return ip is the retcode itself */ 183 return_ip = (unsigned long)&frame->retcode; 184 /* This is: 185 l.ori r11,r0,__NR_sigreturn 186 l.sys 1 187 */ 188 err |= __put_user(0xa960, (short *)(frame->retcode + 0)); 189 err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); 190 err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); 191 err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); 192 193 if (err) 194 return -EFAULT; 195 196 /* Set up registers for signal handler */ 197 regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */ 198 regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ 199 regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */ 200 regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */ 201 regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */ 202 203 /* actually move the usp to reflect the stacked frame */ 204 regs->sp = (unsigned long)frame; 205 206 return 0; 207 } 208 209 static inline void 210 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 211 { 212 int ret; 213 214 ret = setup_rt_frame(ksig, sigmask_to_save(), regs); 215 216 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 217 } 218 219 /* 220 * Note that 'init' is a special process: it doesn't get signals it doesn't 221 * want to handle. Thus you cannot kill init even with a SIGKILL even by 222 * mistake. 223 * 224 * Also note that the regs structure given here as an argument, is the latest 225 * pushed pt_regs. It may or may not be the same as the first pushed registers 226 * when the initial usermode->kernelmode transition took place. Therefore 227 * we can use user_mode(regs) to see if we came directly from kernel or user 228 * mode below. 229 */ 230 231 int do_signal(struct pt_regs *regs, int syscall) 232 { 233 struct ksignal ksig; 234 unsigned long continue_addr = 0; 235 unsigned long restart_addr = 0; 236 unsigned long retval = 0; 237 int restart = 0; 238 239 if (syscall) { 240 continue_addr = regs->pc; 241 restart_addr = continue_addr - 4; 242 retval = regs->gpr[11]; 243 244 /* 245 * Setup syscall restart here so that a debugger will 246 * see the already changed PC. 247 */ 248 switch (retval) { 249 case -ERESTART_RESTARTBLOCK: 250 restart = -2; 251 /* Fall through */ 252 case -ERESTARTNOHAND: 253 case -ERESTARTSYS: 254 case -ERESTARTNOINTR: 255 restart++; 256 regs->gpr[11] = regs->orig_gpr11; 257 regs->pc = restart_addr; 258 break; 259 } 260 } 261 262 /* 263 * Get the signal to deliver. During the call to get_signal the 264 * debugger may change all our registers so we may need to revert 265 * the decision to restart the syscall; specifically, if the PC is 266 * changed, don't restart the syscall. 267 */ 268 if (get_signal(&ksig)) { 269 if (unlikely(restart) && regs->pc == restart_addr) { 270 if (retval == -ERESTARTNOHAND || 271 retval == -ERESTART_RESTARTBLOCK 272 || (retval == -ERESTARTSYS 273 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 274 /* No automatic restart */ 275 regs->gpr[11] = -EINTR; 276 regs->pc = continue_addr; 277 } 278 } 279 handle_signal(&ksig, regs); 280 } else { 281 /* no handler */ 282 restore_saved_sigmask(); 283 /* 284 * Restore pt_regs PC as syscall restart will be handled by 285 * kernel without return to userspace 286 */ 287 if (unlikely(restart) && regs->pc == restart_addr) { 288 regs->pc = continue_addr; 289 return restart; 290 } 291 } 292 293 return 0; 294 } 295 296 asmlinkage int 297 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 298 { 299 do { 300 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 301 schedule(); 302 } else { 303 if (unlikely(!user_mode(regs))) 304 return 0; 305 local_irq_enable(); 306 if (thread_flags & _TIF_SIGPENDING) { 307 int restart = do_signal(regs, syscall); 308 if (unlikely(restart)) { 309 /* 310 * Restart without handlers. 311 * Deal with it without leaving 312 * the kernel space. 313 */ 314 return restart; 315 } 316 syscall = 0; 317 } else { 318 clear_thread_flag(TIF_NOTIFY_RESUME); 319 tracehook_notify_resume(regs); 320 } 321 } 322 local_irq_disable(); 323 thread_flags = current_thread_info()->flags; 324 } while (thread_flags & _TIF_WORK_MASK); 325 return 0; 326 } 327