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 <linux/key.h> 15 #include <asm/hw_breakpoint.h> 16 #include <asm/uaccess.h> 17 #include <asm/unistd.h> 18 19 #include "signal.h" 20 21 /* Log an error when sending an unhandled signal to a process. Controlled 22 * through debug.exception-trace sysctl. 23 */ 24 25 int show_unhandled_signals = 0; 26 27 /* 28 * Allocate space for the signal frame 29 */ 30 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 31 size_t frame_size, int is_32) 32 { 33 unsigned long oldsp, newsp; 34 35 /* Default to using normal stack */ 36 oldsp = get_clean_sp(regs, is_32); 37 38 /* Check for alt stack */ 39 if ((ka->sa.sa_flags & SA_ONSTACK) && 40 current->sas_ss_size && !on_sig_stack(oldsp)) 41 oldsp = (current->sas_ss_sp + current->sas_ss_size); 42 43 /* Get aligned frame */ 44 newsp = (oldsp - frame_size) & ~0xFUL; 45 46 /* Check access */ 47 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 48 return NULL; 49 50 return (void __user *)newsp; 51 } 52 53 54 /* 55 * Restore the user process's signal mask 56 */ 57 void restore_sigmask(sigset_t *set) 58 { 59 sigdelsetmask(set, ~_BLOCKABLE); 60 spin_lock_irq(¤t->sighand->siglock); 61 current->blocked = *set; 62 recalc_sigpending(); 63 spin_unlock_irq(¤t->sighand->siglock); 64 } 65 66 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 67 int has_handler) 68 { 69 unsigned long ret = regs->gpr[3]; 70 int restart = 1; 71 72 /* syscall ? */ 73 if (TRAP(regs) != 0x0C00) 74 return; 75 76 /* error signalled ? */ 77 if (!(regs->ccr & 0x10000000)) 78 return; 79 80 switch (ret) { 81 case ERESTART_RESTARTBLOCK: 82 case ERESTARTNOHAND: 83 /* ERESTARTNOHAND means that the syscall should only be 84 * restarted if there was no handler for the signal, and since 85 * we only get here if there is a handler, we dont restart. 86 */ 87 restart = !has_handler; 88 break; 89 case ERESTARTSYS: 90 /* ERESTARTSYS means to restart the syscall if there is no 91 * handler or the handler was registered with SA_RESTART 92 */ 93 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 94 break; 95 case ERESTARTNOINTR: 96 /* ERESTARTNOINTR means that the syscall should be 97 * called again after the signal handler returns. 98 */ 99 break; 100 default: 101 return; 102 } 103 if (restart) { 104 if (ret == ERESTART_RESTARTBLOCK) 105 regs->gpr[0] = __NR_restart_syscall; 106 else 107 regs->gpr[3] = regs->orig_gpr3; 108 regs->nip -= 4; 109 regs->result = 0; 110 } else { 111 regs->result = -EINTR; 112 regs->gpr[3] = EINTR; 113 regs->ccr |= 0x10000000; 114 } 115 } 116 117 static int do_signal(struct pt_regs *regs) 118 { 119 sigset_t *oldset; 120 siginfo_t info; 121 int signr; 122 struct k_sigaction ka; 123 int ret; 124 int is32 = is_32bit_task(); 125 126 if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK) 127 oldset = ¤t->saved_sigmask; 128 else 129 oldset = ¤t->blocked; 130 131 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 132 133 /* Is there any syscall restart business here ? */ 134 check_syscall_restart(regs, &ka, signr > 0); 135 136 if (signr <= 0) { 137 struct thread_info *ti = current_thread_info(); 138 /* No signal to deliver -- put the saved sigmask back */ 139 if (ti->local_flags & _TLF_RESTORE_SIGMASK) { 140 ti->local_flags &= ~_TLF_RESTORE_SIGMASK; 141 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 142 } 143 regs->trap = 0; 144 return 0; /* no signals delivered */ 145 } 146 147 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 148 /* 149 * Reenable the DABR before delivering the signal to 150 * user space. The DABR will have been cleared if it 151 * triggered inside the kernel. 152 */ 153 if (current->thread.dabr) 154 set_dabr(current->thread.dabr); 155 #endif 156 /* Re-enable the breakpoints for the signal stack */ 157 thread_change_pc(current, regs); 158 159 if (is32) { 160 if (ka.sa.sa_flags & SA_SIGINFO) 161 ret = handle_rt_signal32(signr, &ka, &info, oldset, 162 regs); 163 else 164 ret = handle_signal32(signr, &ka, &info, oldset, 165 regs); 166 } else { 167 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs); 168 } 169 170 regs->trap = 0; 171 if (ret) { 172 spin_lock_irq(¤t->sighand->siglock); 173 sigorsets(¤t->blocked, ¤t->blocked, 174 &ka.sa.sa_mask); 175 if (!(ka.sa.sa_flags & SA_NODEFER)) 176 sigaddset(¤t->blocked, signr); 177 recalc_sigpending(); 178 spin_unlock_irq(¤t->sighand->siglock); 179 180 /* 181 * A signal was successfully delivered; the saved sigmask is in 182 * its frame, and we can clear the TLF_RESTORE_SIGMASK flag. 183 */ 184 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK; 185 186 /* 187 * Let tracing know that we've done the handler setup. 188 */ 189 tracehook_signal_handler(signr, &info, &ka, regs, 190 test_thread_flag(TIF_SINGLESTEP)); 191 } 192 193 return ret; 194 } 195 196 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 197 { 198 if (thread_info_flags & _TIF_SIGPENDING) 199 do_signal(regs); 200 201 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 202 clear_thread_flag(TIF_NOTIFY_RESUME); 203 tracehook_notify_resume(regs); 204 if (current->replacement_session_keyring) 205 key_replace_session_keyring(); 206 } 207 } 208 209 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 210 unsigned long r5, unsigned long r6, unsigned long r7, 211 unsigned long r8, struct pt_regs *regs) 212 { 213 return do_sigaltstack(uss, uoss, regs->gpr[1]); 214 } 215