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