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 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 55 int has_handler) 56 { 57 unsigned long ret = regs->gpr[3]; 58 int restart = 1; 59 60 /* syscall ? */ 61 if (TRAP(regs) != 0x0C00) 62 return; 63 64 /* error signalled ? */ 65 if (!(regs->ccr & 0x10000000)) 66 return; 67 68 switch (ret) { 69 case ERESTART_RESTARTBLOCK: 70 case ERESTARTNOHAND: 71 /* ERESTARTNOHAND means that the syscall should only be 72 * restarted if there was no handler for the signal, and since 73 * we only get here if there is a handler, we dont restart. 74 */ 75 restart = !has_handler; 76 break; 77 case ERESTARTSYS: 78 /* ERESTARTSYS means to restart the syscall if there is no 79 * handler or the handler was registered with SA_RESTART 80 */ 81 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 82 break; 83 case ERESTARTNOINTR: 84 /* ERESTARTNOINTR means that the syscall should be 85 * called again after the signal handler returns. 86 */ 87 break; 88 default: 89 return; 90 } 91 if (restart) { 92 if (ret == ERESTART_RESTARTBLOCK) 93 regs->gpr[0] = __NR_restart_syscall; 94 else 95 regs->gpr[3] = regs->orig_gpr3; 96 regs->nip -= 4; 97 regs->result = 0; 98 } else { 99 regs->result = -EINTR; 100 regs->gpr[3] = EINTR; 101 regs->ccr |= 0x10000000; 102 } 103 } 104 105 static int do_signal(struct pt_regs *regs) 106 { 107 sigset_t *oldset = sigmask_to_save(); 108 siginfo_t info; 109 int signr; 110 struct k_sigaction ka; 111 int ret; 112 int is32 = is_32bit_task(); 113 114 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 115 116 /* Is there any syscall restart business here ? */ 117 check_syscall_restart(regs, &ka, signr > 0); 118 119 if (signr <= 0) { 120 /* No signal to deliver -- put the saved sigmask back */ 121 restore_saved_sigmask(); 122 regs->trap = 0; 123 return 0; /* no signals delivered */ 124 } 125 126 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 127 /* 128 * Reenable the DABR before delivering the signal to 129 * user space. The DABR will have been cleared if it 130 * triggered inside the kernel. 131 */ 132 if (current->thread.dabr) 133 set_dabr(current->thread.dabr); 134 #endif 135 /* Re-enable the breakpoints for the signal stack */ 136 thread_change_pc(current, regs); 137 138 if (is32) { 139 if (ka.sa.sa_flags & SA_SIGINFO) 140 ret = handle_rt_signal32(signr, &ka, &info, oldset, 141 regs); 142 else 143 ret = handle_signal32(signr, &ka, &info, oldset, 144 regs); 145 } else { 146 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs); 147 } 148 149 regs->trap = 0; 150 if (ret) { 151 signal_delivered(signr, &info, &ka, regs, 152 test_thread_flag(TIF_SINGLESTEP)); 153 } 154 155 return ret; 156 } 157 158 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 159 { 160 if (thread_info_flags & _TIF_SIGPENDING) 161 do_signal(regs); 162 163 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 164 clear_thread_flag(TIF_NOTIFY_RESUME); 165 tracehook_notify_resume(regs); 166 } 167 } 168 169 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 170 unsigned long r5, unsigned long r6, unsigned long r7, 171 unsigned long r8, struct pt_regs *regs) 172 { 173 return do_sigaltstack(uss, uoss, regs->gpr[1]); 174 } 175