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6c633d45 | 1 | /* DWARF2 EH unwinding support for Xtensa. |
a945c346 | 2 | Copyright (C) 2008-2024 Free Software Foundation, Inc. |
6c633d45 BW |
3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
748086b7 | 8 | the Free Software Foundation; either version 3, or (at your option) |
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9 | any later version. |
10 | ||
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11 | GCC is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
748086b7 JJ |
16 | Under Section 7 of GPL version 3, you are granted additional |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | You should have received a copy of the GNU General Public License and | |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
6c633d45 BW |
24 | |
25 | /* Do code reading to identify a signal frame, and set the frame | |
26 | state data appropriately. See unwind-dw2-xtensa.c for the structs. | |
27 | Don't use this at all if inhibit_libc is used. */ | |
28 | ||
29 | #ifndef inhibit_libc | |
30 | ||
31 | #include <signal.h> | |
32 | #include <sys/ucontext.h> | |
33 | ||
34 | /* Encoded bytes for Xtensa instructions: | |
35 | movi a2, __NR_rt_sigreturn | |
36 | syscall | |
37 | entry (first byte only) | |
38 | Some of the bytes are endian-dependent. */ | |
39 | ||
40 | #define MOVI_BYTE0 0x22 | |
41 | #define MOVI_BYTE2 225 /* __NR_rt_sigreturn */ | |
42 | #define SYSC_BYTE0 0 | |
43 | #define SYSC_BYTE2 0 | |
44 | ||
45 | #ifdef __XTENSA_EB__ | |
46 | #define MOVI_BYTE1 0x0a | |
47 | #define SYSC_BYTE1 0x05 | |
48 | #define ENTRY_BYTE 0x6c | |
49 | #else | |
50 | #define MOVI_BYTE1 0xa0 | |
51 | #define SYSC_BYTE1 0x50 | |
52 | #define ENTRY_BYTE 0x36 | |
53 | #endif | |
54 | ||
55 | #define MD_FALLBACK_FRAME_STATE_FOR xtensa_fallback_frame_state | |
56 | ||
57 | static _Unwind_Reason_Code | |
58 | xtensa_fallback_frame_state (struct _Unwind_Context *context, | |
59 | _Unwind_FrameState *fs) | |
60 | { | |
61 | unsigned char *pc = context->ra; | |
62 | struct sigcontext *sc; | |
c8338173 MF |
63 | #if defined(__XTENSA_CALL0_ABI__) |
64 | _Unwind_Ptr new_cfa; | |
65 | int i; | |
66 | #endif | |
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67 | |
68 | struct rt_sigframe { | |
1bde7dab | 69 | siginfo_t info; |
883312dc | 70 | ucontext_t uc; |
6c633d45 BW |
71 | } *rt_; |
72 | ||
73 | /* movi a2, __NR_rt_sigreturn; syscall */ | |
74 | if (pc[0] != MOVI_BYTE0 | |
75 | || pc[1] != MOVI_BYTE1 | |
76 | || pc[2] != MOVI_BYTE2 | |
77 | || pc[3] != SYSC_BYTE0 | |
78 | || pc[4] != SYSC_BYTE1 | |
79 | || pc[5] != SYSC_BYTE2) | |
80 | return _URC_END_OF_STACK; | |
81 | ||
c8338173 | 82 | #if defined(__XTENSA_WINDOWED_ABI__) |
6c633d45 BW |
83 | rt_ = context->sp; |
84 | sc = &rt_->uc.uc_mcontext; | |
85 | fs->signal_regs = (_Unwind_Word *) sc->sc_a; | |
86 | ||
87 | /* If the signal arrived just before an ENTRY instruction, find the return | |
88 | address and pretend the signal arrived before executing the CALL. */ | |
89 | if (*(unsigned char *) sc->sc_pc == ENTRY_BYTE) | |
90 | { | |
91 | unsigned callinc = (sc->sc_ps >> 16) & 3; | |
92 | fs->signal_ra = ((sc->sc_a[callinc << 2] & XTENSA_RA_FIELD_MASK) | |
93 | | context->ra_high_bits) - 3; | |
94 | } | |
95 | else | |
96 | fs->signal_ra = sc->sc_pc; | |
c8338173 MF |
97 | #elif defined(__XTENSA_CALL0_ABI__) |
98 | rt_ = context->cfa; | |
99 | sc = &rt_->uc.uc_mcontext; | |
100 | ||
101 | new_cfa = (_Unwind_Ptr) sc; | |
102 | fs->regs.cfa_how = CFA_REG_OFFSET; | |
103 | fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__; | |
104 | fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa; | |
105 | ||
106 | for (i = 0; i < 16; i++) | |
107 | { | |
146e4591 | 108 | fs->regs.how[i] = REG_SAVED_OFFSET; |
c8338173 MF |
109 | fs->regs.reg[i].loc.offset = (_Unwind_Ptr) &(sc->sc_a[i]) - new_cfa; |
110 | } | |
111 | ||
146e4591 | 112 | fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__] = |
c8338173 MF |
113 | REG_SAVED_VAL_OFFSET; |
114 | fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset = | |
115 | (_Unwind_Ptr) (sc->sc_pc) - new_cfa; | |
116 | fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__; | |
117 | #else | |
118 | #error Unsupported Xtensa ABI | |
119 | #endif | |
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120 | |
121 | fs->signal_frame = 1; | |
122 | return _URC_NO_REASON; | |
123 | } | |
124 | ||
590e2636 | 125 | |
6c633d45 | 126 | #endif /* ifdef inhibit_libc */ |