1 /* Dynamic loading of the libgcc unwinder. MIPS customization.
2 Copyright (C) 2020-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
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.
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/>. */
19 #ifndef _ARCH_UNWIND_LINK_H
20 #define _ARCH_UNWIND_LINK_H
23 #include <sys/syscall.h>
25 #define UNWIND_LINK_GETIP 1
26 #define UNWIND_LINK_FRAME_STATE_FOR 1
27 #define UNWIND_LINK_FRAME_ADJUSTMENT 1
28 #define UNWIND_LINK_EXTRA_FIELDS
29 #define UNWIND_LINK_EXTRA_INIT
31 /* MIPS fallback code handle a frame where its FDE can not be obtained
32 (for instance a signal frame) by reading the kernel allocated signal frame
33 and adding '2' to the value of 'sc_pc' [1]. The added value is used to
34 recognize an end of an EH region on mips16 [2].
36 The idea here is to adjust the obtained signal frame ADDR value and remove
37 the libgcc added value by checking if the previous frame is a signal frame
40 [1] libgcc/config/mips/linux-unwind.h from gcc code.
41 [2] gcc/config/mips/mips.h from gcc code. */
44 unwind_arch_adjustment (void *prev, void *addr)
46 uint32_t *pc = (uint32_t *) prev;
51 /* For MIPS16 or microMIPS frame libgcc makes no adjustment. */
52 if ((uintptr_t) pc & 0x3)
55 /* The vDSO contains either
57 24021061 li v0, 0x1061 (rt_sigreturn)
60 24021017 li v0, 0x1017 (sigreturn)
62 if (pc[1] != 0x0000000c)
64 #if _MIPS_SIM == _ABIO32
65 if (pc[0] == (0x24020000 | __NR_sigreturn))
66 return (void *) ((uintptr_t) addr - 2);
68 if (pc[0] == (0x24020000 | __NR_rt_sigreturn))
69 return (void *) ((uintptr_t) addr - 2);
74 #endif /* _ARCH_UNWIND_LINK_H */