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
15EXPORT_SYMBOL(block_signals);
16EXPORT_SYMBOL(unblock_signals);
17
18/*
19 * OK, we're invoking a handler
20 */
21static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
22{
23	sigset_t *oldset = sigmask_to_save();
24	int singlestep = 0;
25	unsigned long sp;
26	int err;
27
28	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
29		singlestep = 1;
30
31	/* Did we come from a system call? */
32	if (PT_REGS_SYSCALL_NR(regs) >= 0) {
33		/* If so, check system call restarting.. */
34		switch (PT_REGS_SYSCALL_RET(regs)) {
35		case -ERESTART_RESTARTBLOCK:
36		case -ERESTARTNOHAND:
37			PT_REGS_SYSCALL_RET(regs) = -EINTR;
38			break;
39
40		case -ERESTARTSYS:
41			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
42				PT_REGS_SYSCALL_RET(regs) = -EINTR;
43				break;
44			}
45		/* fallthrough */
46		case -ERESTARTNOINTR:
47			PT_REGS_RESTART_SYSCALL(regs);
48			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
49			break;
50		}
51	}
52
53	sp = PT_REGS_SP(regs);
54	if ((ksig->ka.sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
55		sp = current->sas_ss_sp + current->sas_ss_size;
56
57#ifdef CONFIG_ARCH_HAS_SC_SIGNALS
58	if (!(ksig->ka.sa.sa_flags & SA_SIGINFO))
59		err = setup_signal_stack_sc(sp, ksig, regs, oldset);
60	else
61#endif
62		err = setup_signal_stack_si(sp, ksig, regs, oldset);
63
64	signal_setup_done(err, ksig, singlestep);
65}
66
67void do_signal(struct pt_regs *regs)
68{
69	struct ksignal ksig;
70	int handled_sig = 0;
71
72	if (get_signal(&ksig)) {
73		handled_sig = 1;
74		/* Whee!  Actually deliver the signal.  */
75		handle_signal(&ksig, regs);
76	}
77
78	/* Did we come from a system call? */
79	if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
80		/* Restart the system call - no handlers present */
81		switch (PT_REGS_SYSCALL_RET(regs)) {
82		case -ERESTARTNOHAND:
83		case -ERESTARTSYS:
84		case -ERESTARTNOINTR:
85			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
86			PT_REGS_RESTART_SYSCALL(regs);
87			break;
88		case -ERESTART_RESTARTBLOCK:
89			PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
90			PT_REGS_RESTART_SYSCALL(regs);
91			break;
92		}
93	}
94
95	/*
96	 * This closes a way to execute a system call on the host.  If
97	 * you set a breakpoint on a system call instruction and singlestep
98	 * from it, the tracing thread used to PTRACE_SINGLESTEP the process
99	 * rather than PTRACE_SYSCALL it, allowing the system call to execute
100	 * on the host.  The tracing thread will check this flag and
101	 * PTRACE_SYSCALL if necessary.
102	 */
103	if (current->ptrace & PT_DTRACE)
104		current->thread.singlestep_syscall =
105			is_syscall(PT_REGS_IP(&current->thread.regs));
106
107	/*
108	 * if there's no signal to deliver, we just put the saved sigmask
109	 * back
110	 */
111	if (!handled_sig)
112		restore_saved_sigmask();
113}
114