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 <linux/tracehook.h> 35 #include <asm/entry.h> 36 #include <asm/ucontext.h> 37 #include <linux/uaccess.h> 38 #include <linux/syscalls.h> 39 #include <asm/cacheflush.h> 40 #include <asm/syscalls.h> 41 42 /* 43 * Do a signal return; undo the signal stack. 44 */ 45 struct sigframe { 46 struct sigcontext sc; 47 unsigned long extramask[_NSIG_WORDS-1]; 48 unsigned long tramp[2]; /* signal trampoline */ 49 }; 50 51 struct rt_sigframe { 52 struct siginfo info; 53 struct ucontext uc; 54 unsigned long tramp[2]; /* signal trampoline */ 55 }; 56 57 static int restore_sigcontext(struct pt_regs *regs, 58 struct sigcontext __user *sc, int *rval_p) 59 { 60 unsigned int err = 0; 61 62 #define COPY(x) {err |= __get_user(regs->x, &sc->regs.x); } 63 COPY(r0); 64 COPY(r1); 65 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 66 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 67 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 68 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 69 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 70 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 71 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 72 COPY(r30); COPY(r31); 73 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 74 #undef COPY 75 76 *rval_p = regs->r3; 77 78 return err; 79 } 80 81 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 82 { 83 struct rt_sigframe __user *frame = 84 (struct rt_sigframe __user *)(regs->r1); 85 86 sigset_t set; 87 int rval; 88 89 /* Always make any pending restarted system calls return -EINTR */ 90 current->restart_block.fn = do_no_restart_syscall; 91 92 if (!access_ok(frame, sizeof(*frame))) 93 goto badframe; 94 95 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 96 goto badframe; 97 98 set_current_blocked(&set); 99 100 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval)) 101 goto badframe; 102 103 if (restore_altstack(&frame->uc.uc_stack)) 104 goto badframe; 105 106 return rval; 107 108 badframe: 109 force_sig(SIGSEGV); 110 return 0; 111 } 112 113 /* 114 * Set up a signal frame. 115 */ 116 117 static int 118 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 119 unsigned long mask) 120 { 121 int err = 0; 122 123 #define COPY(x) {err |= __put_user(regs->x, &sc->regs.x); } 124 COPY(r0); 125 COPY(r1); 126 COPY(r2); COPY(r3); COPY(r4); COPY(r5); 127 COPY(r6); COPY(r7); COPY(r8); COPY(r9); 128 COPY(r10); COPY(r11); COPY(r12); COPY(r13); 129 COPY(r14); COPY(r15); COPY(r16); COPY(r17); 130 COPY(r18); COPY(r19); COPY(r20); COPY(r21); 131 COPY(r22); COPY(r23); COPY(r24); COPY(r25); 132 COPY(r26); COPY(r27); COPY(r28); COPY(r29); 133 COPY(r30); COPY(r31); 134 COPY(pc); COPY(ear); COPY(esr); COPY(fsr); 135 #undef COPY 136 137 err |= __put_user(mask, &sc->oldmask); 138 139 return err; 140 } 141 142 /* 143 * Determine which stack to use.. 144 */ 145 static inline void __user * 146 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size) 147 { 148 /* Default to using normal stack */ 149 unsigned long sp = sigsp(regs->r1, ksig); 150 151 return (void __user *)((sp - frame_size) & -8UL); 152 } 153 154 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 155 struct pt_regs *regs) 156 { 157 struct rt_sigframe __user *frame; 158 int err = 0, sig = ksig->sig; 159 unsigned long address = 0; 160 pmd_t *pmdp; 161 pte_t *ptep; 162 163 frame = get_sigframe(ksig, regs, sizeof(*frame)); 164 165 if (!access_ok(frame, sizeof(*frame))) 166 return -EFAULT; 167 168 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->r1); 175 err |= setup_sigcontext(&frame->uc.uc_mcontext, 176 regs, set->sig[0]); 177 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 178 179 /* Set up to return from userspace. If provided, use a stub 180 already in userspace. */ 181 /* minus 8 is offset to cater for "rtsd r15,8" */ 182 /* addi r12, r0, __NR_sigreturn */ 183 err |= __put_user(0x31800000 | __NR_rt_sigreturn , 184 frame->tramp + 0); 185 /* brki r14, 0x8 */ 186 err |= __put_user(0xb9cc0008, frame->tramp + 1); 187 188 /* Return from sighandler will jump to the tramp. 189 Negative 8 offset because return is rtsd r15, 8 */ 190 regs->r15 = ((unsigned long)frame->tramp)-8; 191 192 address = ((unsigned long)frame->tramp); 193 pmdp = pmd_off(current->mm, address); 194 195 preempt_disable(); 196 ptep = pte_offset_map(pmdp, address); 197 if (pte_present(*ptep)) { 198 address = (unsigned long) page_address(pte_page(*ptep)); 199 /* MS: I need add offset in page */ 200 address += ((unsigned long)frame->tramp) & ~PAGE_MASK; 201 /* MS address is virtual */ 202 address = __virt_to_phys(address); 203 invalidate_icache_range(address, address + 8); 204 flush_dcache_range(address, address + 8); 205 } 206 pte_unmap(ptep); 207 preempt_enable(); 208 if (err) 209 return -EFAULT; 210 211 /* Set up registers for signal handler */ 212 regs->r1 = (unsigned long) frame; 213 214 /* Signal handler args: */ 215 regs->r5 = sig; /* arg 0: signum */ 216 regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */ 217 regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */ 218 /* Offset to handle microblaze rtid r14, 0 */ 219 regs->pc = (unsigned long)ksig->ka.sa.sa_handler; 220 221 #ifdef DEBUG_SIG 222 pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n", 223 current->comm, current->pid, frame, regs->pc); 224 #endif 225 226 return 0; 227 } 228 229 /* Handle restarting system calls */ 230 static inline void 231 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler) 232 { 233 switch (regs->r3) { 234 case -ERESTART_RESTARTBLOCK: 235 case -ERESTARTNOHAND: 236 if (!has_handler) 237 goto do_restart; 238 regs->r3 = -EINTR; 239 break; 240 case -ERESTARTSYS: 241 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) { 242 regs->r3 = -EINTR; 243 break; 244 } 245 fallthrough; 246 case -ERESTARTNOINTR: 247 do_restart: 248 /* offset of 4 bytes to re-execute trap (brki) instruction */ 249 regs->pc -= 4; 250 break; 251 } 252 } 253 254 /* 255 * OK, we're invoking a handler 256 */ 257 258 static void 259 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 260 { 261 sigset_t *oldset = sigmask_to_save(); 262 int ret; 263 264 /* Set up the stack frame */ 265 ret = setup_rt_frame(ksig, oldset, regs); 266 267 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 268 } 269 270 /* 271 * Note that 'init' is a special process: it doesn't get signals it doesn't 272 * want to handle. Thus you cannot kill init even with a SIGKILL even by 273 * mistake. 274 * 275 * Note that we go through the signals twice: once to check the signals that 276 * the kernel can handle, and then we build all the user-level signal handling 277 * stack-frames in one go after that. 278 */ 279 static void do_signal(struct pt_regs *regs, int in_syscall) 280 { 281 struct ksignal ksig; 282 283 #ifdef DEBUG_SIG 284 pr_info("do signal: %p %d\n", regs, in_syscall); 285 pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1, 286 regs->r12, read_thread_flags()); 287 #endif 288 289 if (get_signal(&ksig)) { 290 /* Whee! Actually deliver the signal. */ 291 if (in_syscall) 292 handle_restart(regs, &ksig.ka, 1); 293 handle_signal(&ksig, regs); 294 return; 295 } 296 297 if (in_syscall) 298 handle_restart(regs, NULL, 0); 299 300 /* 301 * If there's no signal to deliver, we just put the saved sigmask 302 * back. 303 */ 304 restore_saved_sigmask(); 305 } 306 307 asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall) 308 { 309 if (test_thread_flag(TIF_SIGPENDING) || 310 test_thread_flag(TIF_NOTIFY_SIGNAL)) 311 do_signal(regs, in_syscall); 312 313 if (test_thread_flag(TIF_NOTIFY_RESUME)) 314 tracehook_notify_resume(regs); 315 } 316