1 /* 2 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com) 3 * Licensed under the GPL 4 */ 5 6 #include "linux/stddef.h" 7 #include "linux/sys.h" 8 #include "linux/sched.h" 9 #include "linux/wait.h" 10 #include "linux/kernel.h" 11 #include "linux/smp_lock.h" 12 #include "linux/module.h" 13 #include "linux/slab.h" 14 #include "linux/tty.h" 15 #include "linux/binfmts.h" 16 #include "linux/ptrace.h" 17 #include "asm/signal.h" 18 #include "asm/uaccess.h" 19 #include "asm/unistd.h" 20 #include "asm/ucontext.h" 21 #include "kern_util.h" 22 #include "signal_kern.h" 23 #include "kern.h" 24 #include "frame_kern.h" 25 #include "sigcontext.h" 26 27 EXPORT_SYMBOL(block_signals); 28 EXPORT_SYMBOL(unblock_signals); 29 30 #define _S(nr) (1<<((nr)-1)) 31 32 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP))) 33 34 /* 35 * OK, we're invoking a handler 36 */ 37 static int handle_signal(struct pt_regs *regs, unsigned long signr, 38 struct k_sigaction *ka, siginfo_t *info, 39 sigset_t *oldset) 40 { 41 unsigned long sp; 42 int err; 43 44 /* Always make any pending restarted system calls return -EINTR */ 45 current_thread_info()->restart_block.fn = do_no_restart_syscall; 46 47 /* Did we come from a system call? */ 48 if(PT_REGS_SYSCALL_NR(regs) >= 0){ 49 /* If so, check system call restarting.. */ 50 switch(PT_REGS_SYSCALL_RET(regs)){ 51 case -ERESTART_RESTARTBLOCK: 52 case -ERESTARTNOHAND: 53 PT_REGS_SYSCALL_RET(regs) = -EINTR; 54 break; 55 56 case -ERESTARTSYS: 57 if (!(ka->sa.sa_flags & SA_RESTART)) { 58 PT_REGS_SYSCALL_RET(regs) = -EINTR; 59 break; 60 } 61 /* fallthrough */ 62 case -ERESTARTNOINTR: 63 PT_REGS_RESTART_SYSCALL(regs); 64 PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs); 65 break; 66 } 67 } 68 69 sp = PT_REGS_SP(regs); 70 if((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0)) 71 sp = current->sas_ss_sp + current->sas_ss_size; 72 73 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS 74 if(!(ka->sa.sa_flags & SA_SIGINFO)) 75 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset); 76 else 77 #endif 78 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset); 79 80 if(err){ 81 spin_lock_irq(¤t->sighand->siglock); 82 current->blocked = *oldset; 83 recalc_sigpending(); 84 spin_unlock_irq(¤t->sighand->siglock); 85 force_sigsegv(signr, current); 86 } else { 87 spin_lock_irq(¤t->sighand->siglock); 88 sigorsets(¤t->blocked, ¤t->blocked, 89 &ka->sa.sa_mask); 90 if(!(ka->sa.sa_flags & SA_NODEFER)) 91 sigaddset(¤t->blocked, signr); 92 recalc_sigpending(); 93 spin_unlock_irq(¤t->sighand->siglock); 94 } 95 96 return err; 97 } 98 99 static int kern_do_signal(struct pt_regs *regs) 100 { 101 struct k_sigaction ka_copy; 102 siginfo_t info; 103 sigset_t *oldset; 104 int sig, handled_sig = 0; 105 106 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 107 oldset = ¤t->saved_sigmask; 108 else 109 oldset = ¤t->blocked; 110 111 while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){ 112 handled_sig = 1; 113 /* Whee! Actually deliver the signal. */ 114 if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){ 115 /* a signal was successfully delivered; the saved 116 * sigmask will have been stored in the signal frame, 117 * and will be restored by sigreturn, so we can simply 118 * clear the TIF_RESTORE_SIGMASK flag */ 119 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 120 clear_thread_flag(TIF_RESTORE_SIGMASK); 121 break; 122 } 123 } 124 125 /* Did we come from a system call? */ 126 if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){ 127 /* Restart the system call - no handlers present */ 128 switch(PT_REGS_SYSCALL_RET(regs)){ 129 case -ERESTARTNOHAND: 130 case -ERESTARTSYS: 131 case -ERESTARTNOINTR: 132 PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs); 133 PT_REGS_RESTART_SYSCALL(regs); 134 break; 135 case -ERESTART_RESTARTBLOCK: 136 PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall; 137 PT_REGS_RESTART_SYSCALL(regs); 138 break; 139 } 140 } 141 142 /* This closes a way to execute a system call on the host. If 143 * you set a breakpoint on a system call instruction and singlestep 144 * from it, the tracing thread used to PTRACE_SINGLESTEP the process 145 * rather than PTRACE_SYSCALL it, allowing the system call to execute 146 * on the host. The tracing thread will check this flag and 147 * PTRACE_SYSCALL if necessary. 148 */ 149 if(current->ptrace & PT_DTRACE) 150 current->thread.singlestep_syscall = 151 is_syscall(PT_REGS_IP(¤t->thread.regs)); 152 153 /* if there's no signal to deliver, we just put the saved sigmask 154 * back */ 155 if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) { 156 clear_thread_flag(TIF_RESTORE_SIGMASK); 157 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 158 } 159 return handled_sig; 160 } 161 162 int do_signal(void) 163 { 164 return kern_do_signal(¤t->thread.regs); 165 } 166 167 /* 168 * Atomically swap in the new signal mask, and wait for a signal. 169 */ 170 long sys_sigsuspend(int history0, int history1, old_sigset_t mask) 171 { 172 mask &= _BLOCKABLE; 173 spin_lock_irq(¤t->sighand->siglock); 174 current->saved_sigmask = current->blocked; 175 siginitset(¤t->blocked, mask); 176 recalc_sigpending(); 177 spin_unlock_irq(¤t->sighand->siglock); 178 179 current->state = TASK_INTERRUPTIBLE; 180 schedule(); 181 set_thread_flag(TIF_RESTORE_SIGMASK); 182 return -ERESTARTNOHAND; 183 } 184 185 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) 186 { 187 return do_sigaltstack(uss, uoss, PT_REGS_SP(¤t->thread.regs)); 188 } 189