1/* 2 * Signal handling 3 * 4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu> 5 * Copyright (C) 2008-2009 PetaLogix 6 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au> 7 * Copyright (C) 2001 NEC Corporation 8 * Copyright (C) 2001 Miles Bader <miles@gnu.org> 9 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima 10 * Copyright (C) 1991,1992 Linus Torvalds 11 * 12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 13 * 14 * This file was was derived from the sh version, arch/sh/kernel/signal.c 15 * 16 * This file is subject to the terms and conditions of the GNU General 17 * Public License. See the file COPYING in the main directory of this 18 * archive for more details. 19 */ 20 21#include <linux/sched.h> 22#include <linux/mm.h> 23#include <linux/smp.h> 24#include <linux/kernel.h> 25#include <linux/signal.h> 26#include <linux/errno.h> 27#include <linux/wait.h> 28#include <linux/ptrace.h> 29#include <linux/unistd.h> 30#include <linux/stddef.h> 31#include <linux/personality.h> 32#include <linux/percpu.h> 33#include <linux/linkage.h> 34#include <asm/entry.h> 35#include <asm/ucontext.h> 36#include <linux/uaccess.h> 37#include <asm/pgtable.h> 38#include <asm/pgalloc.h> 39#include <linux/syscalls.h> 40#include <asm/cacheflush.h> 41#include <asm/syscalls.h> 42 43#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 44 45asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall); 46 47asmlinkage long 48sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 49 struct pt_regs *regs) 50{ 51 return do_sigaltstack(uss, uoss, regs->r1); 52} 53 54/* 55 * Do a signal return; undo the signal stack. 56 */ 57struct sigframe { 58 struct sigcontext sc; 59 unsigned long extramask[_NSIG_WORDS-1]; 60 unsigned long tramp[2]; /* signal trampoline */ 61}; 62 63struct rt_sigframe { 64 struct siginfo info; 65 struct ucontext uc; 66 unsigned long tramp[2]; /* signal trampoline */ 67}; 68 69static int restore_sigcontext(struct pt_regs *regs, 70 struct sigcontext __user *sc, int *rval_p) 71{ 72 unsigned int err = 0; 73 74#define COPY(x) {err |= __get_user(regs->x, &sc->regs.x); } 75 COPY(r0); 76 COPY(r1); 77 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 78 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 79 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 80 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 81 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 82 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 83 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 84 COPY(r30); COPY(r31); 85 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 86#undef COPY 87 88 *rval_p = regs->r3; 89 90 return err; 91} 92 93asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 94{ 95 struct rt_sigframe __user *frame = 96 (struct rt_sigframe __user *)(regs->r1 + STATE_SAVE_ARG_SPACE); 97 98 sigset_t set; 99 int rval; 100 101 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 102 goto badframe; 103 104 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 105 goto badframe; 106 107 sigdelsetmask(&set, ~_BLOCKABLE); 108 spin_lock_irq(¤t->sighand->siglock); 109 current->blocked = set; 110 recalc_sigpending(); 111 spin_unlock_irq(¤t->sighand->siglock); 112 113 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval)) 114 goto badframe; 115 116 /* It is more difficult to avoid calling this function than to 117 call it and ignore errors. */ 118 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1)) 119 goto badframe; 120 121 return rval; 122 123badframe: 124 force_sig(SIGSEGV, current); 125 return 0; 126} 127 128/* 129 * Set up a signal frame. 130 */ 131 132static int 133setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 134 unsigned long mask) 135{ 136 int err = 0; 137 138#define COPY(x) {err |= __put_user(regs->x, &sc->regs.x); } 139 COPY(r0); 140 COPY(r1); 141 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 142 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 143 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 144 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 145 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 146 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 147 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 148 COPY(r30); COPY(r31); 149 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 150#undef COPY 151 152 err |= __put_user(mask, &sc->oldmask); 153 154 return err; 155} 156 157/* 158 * Determine which stack to use.. 159 */ 160static inline void __user * 161get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size) 162{ 163 /* Default to using normal stack */ 164 unsigned long sp = regs->r1; 165 166 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp)) 167 sp = current->sas_ss_sp + current->sas_ss_size; 168 169 return (void __user *)((sp - frame_size) & -8UL); 170} 171 172static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 173 sigset_t *set, struct pt_regs *regs) 174{ 175 struct rt_sigframe __user *frame; 176 int err = 0; 177 int signal; 178 unsigned long address = 0; 179#ifdef CONFIG_MMU 180 pmd_t *pmdp; 181 pte_t *ptep; 182#endif 183 184 frame = get_sigframe(ka, regs, sizeof(*frame)); 185 186 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 187 goto give_sigsegv; 188 189 signal = current_thread_info()->exec_domain 190 && current_thread_info()->exec_domain->signal_invmap 191 && sig < 32 192 ? current_thread_info()->exec_domain->signal_invmap[sig] 193 : sig; 194 195 if (info) 196 err |= copy_siginfo_to_user(&frame->info, info); 197 198 /* Create the ucontext. */ 199 err |= __put_user(0, &frame->uc.uc_flags); 200 err |= __put_user(0, &frame->uc.uc_link); 201 err |= __put_user((void *)current->sas_ss_sp, 202 &frame->uc.uc_stack.ss_sp); 203 err |= __put_user(sas_ss_flags(regs->r1), 204 &frame->uc.uc_stack.ss_flags); 205 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 206 err |= setup_sigcontext(&frame->uc.uc_mcontext, 207 regs, set->sig[0]); 208 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 209 210 /* Set up to return from userspace. If provided, use a stub 211 already in userspace. */ 212 /* minus 8 is offset to cater for "rtsd r15,8" */ 213 /* addi r12, r0, __NR_sigreturn */ 214 err |= __put_user(0x31800000 | __NR_rt_sigreturn , 215 frame->tramp + 0); 216 /* brki r14, 0x8 */ 217 err |= __put_user(0xb9cc0008, frame->tramp + 1); 218 219 /* Return from sighandler will jump to the tramp. 220 Negative 8 offset because return is rtsd r15, 8 */ 221 regs->r15 = ((unsigned long)frame->tramp)-8; 222 223 address = ((unsigned long)frame->tramp); 224#ifdef CONFIG_MMU 225 pmdp = pmd_offset(pud_offset( 226 pgd_offset(current->mm, address), 227 address), address); 228 229 preempt_disable(); 230 ptep = pte_offset_map(pmdp, address); 231 if (pte_present(*ptep)) { 232 address = (unsigned long) page_address(pte_page(*ptep)); 233 /* MS: I need add offset in page */ 234 address += ((unsigned long)frame->tramp) & ~PAGE_MASK; 235 /* MS address is virtual */ 236 address = virt_to_phys(address); 237 invalidate_icache_range(address, address + 8); 238 flush_dcache_range(address, address + 8); 239 } 240 pte_unmap(ptep); 241 preempt_enable(); 242#else 243 flush_icache_range(address, address + 8); 244 flush_dcache_range(address, address + 8); 245#endif 246 if (err) 247 goto give_sigsegv; 248 249 /* Set up registers for signal handler */ 250 regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE; 251 252 /* Signal handler args: */ 253 regs->r5 = signal; /* arg 0: signum */ 254 regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */ 255 regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */ 256 /* Offset to handle microblaze rtid r14, 0 */ 257 regs->pc = (unsigned long)ka->sa.sa_handler; 258 259 set_fs(USER_DS); 260 261 /* the tracer may want to single-step inside the handler */ 262 if (test_thread_flag(TIF_SINGLESTEP)) 263 ptrace_notify(SIGTRAP); 264 265#ifdef DEBUG_SIG 266 printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n", 267 current->comm, current->pid, frame, regs->pc); 268#endif 269 270 return; 271 272give_sigsegv: 273 if (sig == SIGSEGV) 274 ka->sa.sa_handler = SIG_DFL; 275 force_sig(SIGSEGV, current); 276} 277 278/* Handle restarting system calls */ 279static inline void 280handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler) 281{ 282 switch (regs->r3) { 283 case -ERESTART_RESTARTBLOCK: 284 case -ERESTARTNOHAND: 285 if (!has_handler) 286 goto do_restart; 287 regs->r3 = -EINTR; 288 break; 289 case -ERESTARTSYS: 290 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) { 291 regs->r3 = -EINTR; 292 break; 293 } 294 /* fallthrough */ 295 case -ERESTARTNOINTR: 296do_restart: 297 /* offset of 4 bytes to re-execute trap (brki) instruction */ 298#ifndef CONFIG_MMU 299 regs->pc -= 4; 300#else 301 /* offset of 8 bytes required = 4 for rtbd 302 offset, plus 4 for size of 303 "brki r14,8" 304 instruction. */ 305 regs->pc -= 8; 306#endif 307 break; 308 } 309} 310 311/* 312 * OK, we're invoking a handler 313 */ 314 315static int 316handle_signal(unsigned long sig, struct k_sigaction *ka, 317 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 318{ 319 /* Set up the stack frame */ 320 if (ka->sa.sa_flags & SA_SIGINFO) 321 setup_rt_frame(sig, ka, info, oldset, regs); 322 else 323 setup_rt_frame(sig, ka, NULL, oldset, regs); 324 325 if (ka->sa.sa_flags & SA_ONESHOT) 326 ka->sa.sa_handler = SIG_DFL; 327 328 if (!(ka->sa.sa_flags & SA_NODEFER)) { 329 spin_lock_irq(¤t->sighand->siglock); 330 sigorsets(¤t->blocked, 331 ¤t->blocked, &ka->sa.sa_mask); 332 sigaddset(¤t->blocked, sig); 333 recalc_sigpending(); 334 spin_unlock_irq(¤t->sighand->siglock); 335 } 336 return 1; 337} 338 339/* 340 * Note that 'init' is a special process: it doesn't get signals it doesn't 341 * want to handle. Thus you cannot kill init even with a SIGKILL even by 342 * mistake. 343 * 344 * Note that we go through the signals twice: once to check the signals that 345 * the kernel can handle, and then we build all the user-level signal handling 346 * stack-frames in one go after that. 347 */ 348int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall) 349{ 350 siginfo_t info; 351 int signr; 352 struct k_sigaction ka; 353#ifdef DEBUG_SIG 354 printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall); 355 printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1, 356 regs->r12, current_thread_info()->flags); 357#endif 358 /* 359 * We want the common case to go fast, which 360 * is why we may in certain cases get here from 361 * kernel mode. Just return without doing anything 362 * if so. 363 */ 364 if (kernel_mode(regs)) 365 return 1; 366 367 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 368 oldset = ¤t->saved_sigmask; 369 else 370 oldset = ¤t->blocked; 371 372 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 373 if (signr > 0) { 374 /* Whee! Actually deliver the signal. */ 375 if (in_syscall) 376 handle_restart(regs, &ka, 1); 377 if (handle_signal(signr, &ka, &info, oldset, regs)) { 378 /* 379 * A signal was successfully delivered; the saved 380 * sigmask will have been stored in the signal frame, 381 * and will be restored by sigreturn, so we can simply 382 * clear the TS_RESTORE_SIGMASK flag. 383 */ 384 current_thread_info()->status &= 385 ~TS_RESTORE_SIGMASK; 386 } 387 return 1; 388 } 389 390 if (in_syscall) 391 handle_restart(regs, NULL, 0); 392 393 /* 394 * If there's no signal to deliver, we just put the saved sigmask 395 * back. 396 */ 397 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 398 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 399 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 400 } 401 402 /* Did we come from a system call? */ 403 return 0; 404} 405