Merge branch 'topic/docbook-fix' into for-linus
[linux-2.6] / arch / um / kernel / signal.c
1 /*
2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Licensed under the GPL
4  */
5
6 #include <linux/module.h>
7 #include <linux/ptrace.h>
8 #include <linux/sched.h>
9 #include <asm/siginfo.h>
10 #include <asm/signal.h>
11 #include <asm/unistd.h>
12 #include "frame_kern.h"
13 #include "kern_util.h"
14 #include <sysdep/sigcontext.h>
15
16 EXPORT_SYMBOL(block_signals);
17 EXPORT_SYMBOL(unblock_signals);
18
19 #define _S(nr) (1<<((nr)-1))
20
21 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
22
23 /*
24  * OK, we're invoking a handler
25  */
26 static int handle_signal(struct pt_regs *regs, unsigned long signr,
27                          struct k_sigaction *ka, siginfo_t *info,
28                          sigset_t *oldset)
29 {
30         unsigned long sp;
31         int err;
32
33         /* Always make any pending restarted system calls return -EINTR */
34         current_thread_info()->restart_block.fn = do_no_restart_syscall;
35
36         /* Did we come from a system call? */
37         if (PT_REGS_SYSCALL_NR(regs) >= 0) {
38                 /* If so, check system call restarting.. */
39                 switch (PT_REGS_SYSCALL_RET(regs)) {
40                 case -ERESTART_RESTARTBLOCK:
41                 case -ERESTARTNOHAND:
42                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
43                         break;
44
45                 case -ERESTARTSYS:
46                         if (!(ka->sa.sa_flags & SA_RESTART)) {
47                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
48                                 break;
49                         }
50                 /* fallthrough */
51                 case -ERESTARTNOINTR:
52                         PT_REGS_RESTART_SYSCALL(regs);
53                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
54                         break;
55                 }
56         }
57
58         sp = PT_REGS_SP(regs);
59         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
60                 sp = current->sas_ss_sp + current->sas_ss_size;
61
62 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
63         if (!(ka->sa.sa_flags & SA_SIGINFO))
64                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
65         else
66 #endif
67                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
68
69         if (err) {
70                 spin_lock_irq(&current->sighand->siglock);
71                 current->blocked = *oldset;
72                 recalc_sigpending();
73                 spin_unlock_irq(&current->sighand->siglock);
74                 force_sigsegv(signr, current);
75         } else {
76                 spin_lock_irq(&current->sighand->siglock);
77                 sigorsets(&current->blocked, &current->blocked,
78                           &ka->sa.sa_mask);
79                 if (!(ka->sa.sa_flags & SA_NODEFER))
80                         sigaddset(&current->blocked, signr);
81                 recalc_sigpending();
82                 spin_unlock_irq(&current->sighand->siglock);
83         }
84
85         return err;
86 }
87
88 static int kern_do_signal(struct pt_regs *regs)
89 {
90         struct k_sigaction ka_copy;
91         siginfo_t info;
92         sigset_t *oldset;
93         int sig, handled_sig = 0;
94
95         if (test_thread_flag(TIF_RESTORE_SIGMASK))
96                 oldset = &current->saved_sigmask;
97         else
98                 oldset = &current->blocked;
99
100         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
101                 handled_sig = 1;
102                 /* Whee!  Actually deliver the signal.  */
103                 if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
104                         /*
105                          * a signal was successfully delivered; the saved
106                          * sigmask will have been stored in the signal frame,
107                          * and will be restored by sigreturn, so we can simply
108                          * clear the TIF_RESTORE_SIGMASK flag
109                          */
110                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
111                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
112                         break;
113                 }
114         }
115
116         /* Did we come from a system call? */
117         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
118                 /* Restart the system call - no handlers present */
119                 switch (PT_REGS_SYSCALL_RET(regs)) {
120                 case -ERESTARTNOHAND:
121                 case -ERESTARTSYS:
122                 case -ERESTARTNOINTR:
123                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
124                         PT_REGS_RESTART_SYSCALL(regs);
125                         break;
126                 case -ERESTART_RESTARTBLOCK:
127                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
128                         PT_REGS_RESTART_SYSCALL(regs);
129                         break;
130                 }
131         }
132
133         /*
134          * This closes a way to execute a system call on the host.  If
135          * you set a breakpoint on a system call instruction and singlestep
136          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
137          * rather than PTRACE_SYSCALL it, allowing the system call to execute
138          * on the host.  The tracing thread will check this flag and
139          * PTRACE_SYSCALL if necessary.
140          */
141         if (current->ptrace & PT_DTRACE)
142                 current->thread.singlestep_syscall =
143                         is_syscall(PT_REGS_IP(&current->thread.regs));
144
145         /*
146          * if there's no signal to deliver, we just put the saved sigmask
147          * back
148          */
149         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
150                 clear_thread_flag(TIF_RESTORE_SIGMASK);
151                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
152         }
153         return handled_sig;
154 }
155
156 int do_signal(void)
157 {
158         return kern_do_signal(&current->thread.regs);
159 }
160
161 /*
162  * Atomically swap in the new signal mask, and wait for a signal.
163  */
164 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
165 {
166         mask &= _BLOCKABLE;
167         spin_lock_irq(&current->sighand->siglock);
168         current->saved_sigmask = current->blocked;
169         siginitset(&current->blocked, mask);
170         recalc_sigpending();
171         spin_unlock_irq(&current->sighand->siglock);
172
173         current->state = TASK_INTERRUPTIBLE;
174         schedule();
175         set_thread_flag(TIF_RESTORE_SIGMASK);
176         return -ERESTARTNOHAND;
177 }
178
179 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
180 {
181         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
182 }