1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6 #include <linux/module.h>
7 #include <linux/ptrace.h>
8 #include <linux/sched.h>
9 #include <linux/ftrace.h>
10 #include <asm/siginfo.h>
11 #include <asm/signal.h>
12 #include <asm/unistd.h>
13 #include <frame_kern.h>
14 #include <kern_util.h>
15 #include <os.h>
16
17 EXPORT_SYMBOL(block_signals);
18 EXPORT_SYMBOL(unblock_signals);
19
block_signals_trace(void)20 void block_signals_trace(void)
21 {
22 block_signals();
23 if (current_thread_info())
24 trace_hardirqs_off();
25 }
26
unblock_signals_trace(void)27 void unblock_signals_trace(void)
28 {
29 if (current_thread_info())
30 trace_hardirqs_on();
31 unblock_signals();
32 }
33
um_trace_signals_on(void)34 void um_trace_signals_on(void)
35 {
36 if (current_thread_info())
37 trace_hardirqs_on();
38 }
39
um_trace_signals_off(void)40 void um_trace_signals_off(void)
41 {
42 if (current_thread_info())
43 trace_hardirqs_off();
44 }
45
46 /*
47 * OK, we're invoking a handler
48 */
handle_signal(struct ksignal * ksig,struct pt_regs * regs)49 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
50 {
51 sigset_t *oldset = sigmask_to_save();
52 int singlestep = 0;
53 unsigned long sp;
54 int err;
55
56 if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
57 singlestep = 1;
58
59 /* Did we come from a system call? */
60 if (PT_REGS_SYSCALL_NR(regs) >= 0) {
61 /* If so, check system call restarting.. */
62 switch (PT_REGS_SYSCALL_RET(regs)) {
63 case -ERESTART_RESTARTBLOCK:
64 case -ERESTARTNOHAND:
65 PT_REGS_SYSCALL_RET(regs) = -EINTR;
66 break;
67
68 case -ERESTARTSYS:
69 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
70 PT_REGS_SYSCALL_RET(regs) = -EINTR;
71 break;
72 }
73 fallthrough;
74 case -ERESTARTNOINTR:
75 PT_REGS_RESTART_SYSCALL(regs);
76 PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
77 break;
78 }
79 }
80
81 sp = PT_REGS_SP(regs);
82 if ((ksig->ka.sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
83 sp = current->sas_ss_sp + current->sas_ss_size;
84
85 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
86 if (!(ksig->ka.sa.sa_flags & SA_SIGINFO))
87 err = setup_signal_stack_sc(sp, ksig, regs, oldset);
88 else
89 #endif
90 err = setup_signal_stack_si(sp, ksig, regs, oldset);
91
92 signal_setup_done(err, ksig, singlestep);
93 }
94
do_signal(struct pt_regs * regs)95 void do_signal(struct pt_regs *regs)
96 {
97 struct ksignal ksig;
98 int handled_sig = 0;
99
100 while (get_signal(&ksig)) {
101 handled_sig = 1;
102 /* Whee! Actually deliver the signal. */
103 handle_signal(&ksig, regs);
104 }
105
106 /* Did we come from a system call? */
107 if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
108 /* Restart the system call - no handlers present */
109 switch (PT_REGS_SYSCALL_RET(regs)) {
110 case -ERESTARTNOHAND:
111 case -ERESTARTSYS:
112 case -ERESTARTNOINTR:
113 PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
114 PT_REGS_RESTART_SYSCALL(regs);
115 break;
116 case -ERESTART_RESTARTBLOCK:
117 PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
118 PT_REGS_RESTART_SYSCALL(regs);
119 break;
120 }
121 }
122
123 /*
124 * This closes a way to execute a system call on the host. If
125 * you set a breakpoint on a system call instruction and singlestep
126 * from it, the tracing thread used to PTRACE_SINGLESTEP the process
127 * rather than PTRACE_SYSCALL it, allowing the system call to execute
128 * on the host. The tracing thread will check this flag and
129 * PTRACE_SYSCALL if necessary.
130 */
131 if (current->ptrace & PT_DTRACE)
132 current->thread.singlestep_syscall =
133 is_syscall(PT_REGS_IP(¤t->thread.regs));
134
135 /*
136 * if there's no signal to deliver, we just put the saved sigmask
137 * back
138 */
139 if (!handled_sig)
140 restore_saved_sigmask();
141 }
142
