1 /* 2 * Common signal handling code for both 32 and 64 bits 3 * 4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration 5 * Extracted from signal_32.c and signal_64.c 6 * 7 * This file is subject to the terms and conditions of the GNU General 8 * Public License. See the file README.legal in the main directory of 9 * this archive for more details. 10 */ 11 12 #include <linux/tracehook.h> 13 #include <linux/signal.h> 14 #include <asm/uaccess.h> 15 #include <asm/unistd.h> 16 17 #include "signal.h" 18 19 /* Log an error when sending an unhandled signal to a process. Controlled 20 * through debug.exception-trace sysctl. 21 */ 22 23 int show_unhandled_signals = 0; 24 25 /* 26 * Allocate space for the signal frame 27 */ 28 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 29 size_t frame_size, int is_32) 30 { 31 unsigned long oldsp, newsp; 32 33 /* Default to using normal stack */ 34 oldsp = get_clean_sp(regs, is_32); 35 36 /* Check for alt stack */ 37 if ((ka->sa.sa_flags & SA_ONSTACK) && 38 current->sas_ss_size && !on_sig_stack(oldsp)) 39 oldsp = (current->sas_ss_sp + current->sas_ss_size); 40 41 /* Get aligned frame */ 42 newsp = (oldsp - frame_size) & ~0xFUL; 43 44 /* Check access */ 45 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 46 return NULL; 47 48 return (void __user *)newsp; 49 } 50 51 52 /* 53 * Restore the user process's signal mask 54 */ 55 void restore_sigmask(sigset_t *set) 56 { 57 sigdelsetmask(set, ~_BLOCKABLE); 58 spin_lock_irq(¤t->sighand->siglock); 59 current->blocked = *set; 60 recalc_sigpending(); 61 spin_unlock_irq(¤t->sighand->siglock); 62 } 63 64 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 65 int has_handler) 66 { 67 unsigned long ret = regs->gpr[3]; 68 int restart = 1; 69 70 /* syscall ? */ 71 if (TRAP(regs) != 0x0C00) 72 return; 73 74 /* error signalled ? */ 75 if (!(regs->ccr & 0x10000000)) 76 return; 77 78 switch (ret) { 79 case ERESTART_RESTARTBLOCK: 80 case ERESTARTNOHAND: 81 /* ERESTARTNOHAND means that the syscall should only be 82 * restarted if there was no handler for the signal, and since 83 * we only get here if there is a handler, we dont restart. 84 */ 85 restart = !has_handler; 86 break; 87 case ERESTARTSYS: 88 /* ERESTARTSYS means to restart the syscall if there is no 89 * handler or the handler was registered with SA_RESTART 90 */ 91 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 92 break; 93 case ERESTARTNOINTR: 94 /* ERESTARTNOINTR means that the syscall should be 95 * called again after the signal handler returns. 96 */ 97 break; 98 default: 99 return; 100 } 101 if (restart) { 102 if (ret == ERESTART_RESTARTBLOCK) 103 regs->gpr[0] = __NR_restart_syscall; 104 else 105 regs->gpr[3] = regs->orig_gpr3; 106 regs->nip -= 4; 107 regs->result = 0; 108 } else { 109 regs->result = -EINTR; 110 regs->gpr[3] = EINTR; 111 regs->ccr |= 0x10000000; 112 } 113 } 114 115 static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs) 116 { 117 siginfo_t info; 118 int signr; 119 struct k_sigaction ka; 120 int ret; 121 int is32 = is_32bit_task(); 122 123 if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK) 124 oldset = ¤t->saved_sigmask; 125 else if (!oldset) 126 oldset = ¤t->blocked; 127 128 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 129 130 /* Is there any syscall restart business here ? */ 131 check_syscall_restart(regs, &ka, signr > 0); 132 133 if (signr <= 0) { 134 struct thread_info *ti = current_thread_info(); 135 /* No signal to deliver -- put the saved sigmask back */ 136 if (ti->local_flags & _TLF_RESTORE_SIGMASK) { 137 ti->local_flags &= ~_TLF_RESTORE_SIGMASK; 138 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 139 } 140 return 0; /* no signals delivered */ 141 } 142 143 /* 144 * Reenable the DABR before delivering the signal to 145 * user space. The DABR will have been cleared if it 146 * triggered inside the kernel. 147 */ 148 if (current->thread.dabr) { 149 set_dabr(current->thread.dabr); 150 #if defined(CONFIG_BOOKE) 151 mtspr(SPRN_DBCR0, current->thread.dbcr0); 152 #endif 153 } 154 155 if (is32) { 156 if (ka.sa.sa_flags & SA_SIGINFO) 157 ret = handle_rt_signal32(signr, &ka, &info, oldset, 158 regs); 159 else 160 ret = handle_signal32(signr, &ka, &info, oldset, 161 regs); 162 } else { 163 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs); 164 } 165 166 if (ret) { 167 spin_lock_irq(¤t->sighand->siglock); 168 sigorsets(¤t->blocked, ¤t->blocked, 169 &ka.sa.sa_mask); 170 if (!(ka.sa.sa_flags & SA_NODEFER)) 171 sigaddset(¤t->blocked, signr); 172 recalc_sigpending(); 173 spin_unlock_irq(¤t->sighand->siglock); 174 175 /* 176 * A signal was successfully delivered; the saved sigmask is in 177 * its frame, and we can clear the TLF_RESTORE_SIGMASK flag. 178 */ 179 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK; 180 181 /* 182 * Let tracing know that we've done the handler setup. 183 */ 184 tracehook_signal_handler(signr, &info, &ka, regs, 185 test_thread_flag(TIF_SINGLESTEP)); 186 } 187 188 return ret; 189 } 190 191 void do_signal(struct pt_regs *regs, unsigned long thread_info_flags) 192 { 193 if (thread_info_flags & _TIF_SIGPENDING) 194 do_signal_pending(NULL, regs); 195 196 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 197 clear_thread_flag(TIF_NOTIFY_RESUME); 198 tracehook_notify_resume(regs); 199 } 200 } 201 202 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 203 unsigned long r5, unsigned long r6, unsigned long r7, 204 unsigned long r8, struct pt_regs *regs) 205 { 206 return do_sigaltstack(uss, uoss, regs->gpr[1]); 207 } 208