1 /* Copyright (C) 2005-2022 Free Software Foundation, Inc.
2
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <stddef.h>
20 #include <asm/sigcontext.h>
21 #include <linux/signal.h>
22 #include <asm-generic/ucontext.h>
23 #include <sys/syscall.h>
24
25 int
_identify_sighandler(unsigned long fp,unsigned long pc,unsigned long * pprev_fp,unsigned long * pprev_pc,unsigned long * retaddr)26 _identify_sighandler (unsigned long fp, unsigned long pc,
27 unsigned long *pprev_fp, unsigned long *pprev_pc,
28 unsigned long *retaddr)
29 {
30 unsigned long *tramp = 0;
31 struct ucontext *uc;
32
33 if (*retaddr == 0)
34 {
35 /* Kernel inserts the tramp between the signal handler frame and the
36 caller frame in signal handling. */
37 tramp = (unsigned long *) pc;
38 tramp += 2;
39 if ((*tramp == (0x31800000 | __NR_rt_sigreturn))
40 && (*(tramp+1) == 0xb9cc0008))
41 {
42 /* Signal handler function argument are:
43 int sig_num, siginfo_t * info, void * ucontext
44 therefore ucontext is the 3rd argument. */
45 unsigned long ucptr = ((unsigned long) tramp
46 - sizeof (struct ucontext));
47 uc = (struct ucontext *) ucptr;
48 *pprev_pc = uc->uc_mcontext.regs.pc;
49 /* Need to record the return address since the return address of the
50 function which causes this signal may not be recorded in the
51 stack. */
52 *pprev_fp = uc->uc_mcontext.regs.r1;
53 *retaddr = uc->uc_mcontext.regs.r15;
54 /* It is a signal handler. */
55 return 1;
56 }
57 }
58 return 0;
59 }
60