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 set_current_blocked(set); 61 } 62 63 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 64 int has_handler) 65 { 66 unsigned long ret = regs->gpr[3]; 67 int restart = 1; 68 69 /* syscall ? */ 70 if (TRAP(regs) != 0x0C00) 71 return; 72 73 /* error signalled ? */ 74 if (!(regs->ccr & 0x10000000)) 75 return; 76 77 switch (ret) { 78 case ERESTART_RESTARTBLOCK: 79 case ERESTARTNOHAND: 80 /* ERESTARTNOHAND means that the syscall should only be 81 * restarted if there was no handler for the signal, and since 82 * we only get here if there is a handler, we dont restart. 83 */ 84 restart = !has_handler; 85 break; 86 case ERESTARTSYS: 87 /* ERESTARTSYS means to restart the syscall if there is no 88 * handler or the handler was registered with SA_RESTART 89 */ 90 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 91 break; 92 case ERESTARTNOINTR: 93 /* ERESTARTNOINTR means that the syscall should be 94 * called again after the signal handler returns. 95 */ 96 break; 97 default: 98 return; 99 } 100 if (restart) { 101 if (ret == ERESTART_RESTARTBLOCK) 102 regs->gpr[0] = __NR_restart_syscall; 103 else 104 regs->gpr[3] = regs->orig_gpr3; 105 regs->nip -= 4; 106 regs->result = 0; 107 } else { 108 regs->result = -EINTR; 109 regs->gpr[3] = EINTR; 110 regs->ccr |= 0x10000000; 111 } 112 } 113 114 static int do_signal(struct pt_regs *regs) 115 { 116 sigset_t *oldset; 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 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 regs->trap = 0; 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 regs->trap = 0; 168 if (ret) { 169 block_sigmask(&ka, signr); 170 171 /* 172 * A signal was successfully delivered; the saved sigmask is in 173 * its frame, and we can clear the TLF_RESTORE_SIGMASK flag. 174 */ 175 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK; 176 177 /* 178 * Let tracing know that we've done the handler setup. 179 */ 180 tracehook_signal_handler(signr, &info, &ka, regs, 181 test_thread_flag(TIF_SINGLESTEP)); 182 } 183 184 return ret; 185 } 186 187 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 188 { 189 if (thread_info_flags & _TIF_SIGPENDING) 190 do_signal(regs); 191 192 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 193 clear_thread_flag(TIF_NOTIFY_RESUME); 194 tracehook_notify_resume(regs); 195 if (current->replacement_session_keyring) 196 key_replace_session_keyring(); 197 } 198 } 199 200 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 201 unsigned long r5, unsigned long r6, unsigned long r7, 202 unsigned long r8, struct pt_regs *regs) 203 { 204 return do_sigaltstack(uss, uoss, regs->gpr[1]); 205 } 206