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 #include <asm/debug.h> 19 20 #include "signal.h" 21 22 /* Log an error when sending an unhandled signal to a process. Controlled 23 * through debug.exception-trace sysctl. 24 */ 25 26 int show_unhandled_signals = 0; 27 28 /* 29 * Allocate space for the signal frame 30 */ 31 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 32 size_t frame_size, int is_32) 33 { 34 unsigned long oldsp, newsp; 35 36 /* Default to using normal stack */ 37 oldsp = get_clean_sp(regs, is_32); 38 39 /* Check for alt stack */ 40 if ((ka->sa.sa_flags & SA_ONSTACK) && 41 current->sas_ss_size && !on_sig_stack(oldsp)) 42 oldsp = (current->sas_ss_sp + current->sas_ss_size); 43 44 /* Get aligned frame */ 45 newsp = (oldsp - frame_size) & ~0xFUL; 46 47 /* Check access */ 48 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 49 return NULL; 50 51 return (void __user *)newsp; 52 } 53 54 55 /* 56 * Restore the user process's signal mask 57 */ 58 void restore_sigmask(sigset_t *set) 59 { 60 sigdelsetmask(set, ~_BLOCKABLE); 61 set_current_blocked(set); 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(struct pt_regs *regs) 116 { 117 sigset_t *oldset; 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 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 regs->trap = 0; 142 return 0; /* no signals delivered */ 143 } 144 145 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 146 /* 147 * Reenable the DABR before delivering the signal to 148 * user space. The DABR will have been cleared if it 149 * triggered inside the kernel. 150 */ 151 if (current->thread.dabr) 152 set_dabr(current->thread.dabr); 153 #endif 154 /* Re-enable the breakpoints for the signal stack */ 155 thread_change_pc(current, regs); 156 157 if (is32) { 158 if (ka.sa.sa_flags & SA_SIGINFO) 159 ret = handle_rt_signal32(signr, &ka, &info, oldset, 160 regs); 161 else 162 ret = handle_signal32(signr, &ka, &info, oldset, 163 regs); 164 } else { 165 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs); 166 } 167 168 regs->trap = 0; 169 if (ret) { 170 block_sigmask(&ka, signr); 171 172 /* 173 * A signal was successfully delivered; the saved sigmask is in 174 * its frame, and we can clear the TLF_RESTORE_SIGMASK flag. 175 */ 176 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK; 177 178 /* 179 * Let tracing know that we've done the handler setup. 180 */ 181 tracehook_signal_handler(signr, &info, &ka, regs, 182 test_thread_flag(TIF_SINGLESTEP)); 183 } 184 185 return ret; 186 } 187 188 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 189 { 190 if (thread_info_flags & _TIF_SIGPENDING) 191 do_signal(regs); 192 193 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 194 clear_thread_flag(TIF_NOTIFY_RESUME); 195 tracehook_notify_resume(regs); 196 if (current->replacement_session_keyring) 197 key_replace_session_keyring(); 198 } 199 } 200 201 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 202 unsigned long r5, unsigned long r6, unsigned long r7, 203 unsigned long r8, struct pt_regs *regs) 204 { 205 return do_sigaltstack(uss, uoss, regs->gpr[1]); 206 } 207