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8662eb14 | 1 | /* DWARF2 EH unwinding support for MIPS Linux. |
99dee823 | 2 | Copyright (C) 2004-2021 Free Software Foundation, Inc. |
8662eb14 AM |
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) |
8662eb14 AM |
9 | any later version. |
10 | ||
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/>. */ | |
8662eb14 AM |
24 | |
25 | #ifndef inhibit_libc | |
26 | /* Do code reading to identify a signal frame, and set the frame | |
27 | state data appropriately. See unwind-dw2.c for the structs. */ | |
28 | ||
29 | #include <signal.h> | |
726f49c3 | 30 | #include <sys/syscall.h> |
8662eb14 AM |
31 | |
32 | /* The third parameter to the signal handler points to something with | |
33 | * this structure defined in asm/ucontext.h, but the name clashes with | |
34 | * struct ucontext from sys/ucontext.h so this private copy is used. */ | |
35 | typedef struct _sig_ucontext { | |
36 | unsigned long uc_flags; | |
37 | struct _sig_ucontext *uc_link; | |
38 | stack_t uc_stack; | |
39 | struct sigcontext uc_mcontext; | |
40 | sigset_t uc_sigmask; | |
41 | } _sig_ucontext_t; | |
42 | ||
43 | #define MD_FALLBACK_FRAME_STATE_FOR mips_fallback_frame_state | |
44 | ||
45 | static _Unwind_Reason_Code | |
46 | mips_fallback_frame_state (struct _Unwind_Context *context, | |
47 | _Unwind_FrameState *fs) | |
48 | { | |
49 | u_int32_t *pc = (u_int32_t *) context->ra; | |
50 | struct sigcontext *sc; | |
25127042 | 51 | _Unwind_Ptr new_cfa, reg_offset; |
8662eb14 AM |
52 | int i; |
53 | ||
22c4c869 CM |
54 | /* A MIPS16 or microMIPS frame. Signal frames always use the standard |
55 | ISA encoding. */ | |
56 | if ((_Unwind_Ptr) pc & 3) | |
57 | return _URC_END_OF_STACK; | |
58 | ||
8662eb14 AM |
59 | /* 24021061 li v0, 0x1061 (rt_sigreturn)*/ |
60 | /* 0000000c syscall */ | |
61 | /* or */ | |
62 | /* 24021017 li v0, 0x1017 (sigreturn) */ | |
63 | /* 0000000c syscall */ | |
fa807ff6 | 64 | if (pc[1] != 0x0000000c) |
8662eb14 | 65 | return _URC_END_OF_STACK; |
fa807ff6 RS |
66 | #if _MIPS_SIM == _ABIO32 |
67 | if (pc[0] == (0x24020000 | __NR_sigreturn)) | |
8662eb14 AM |
68 | { |
69 | struct sigframe { | |
cc3c24ed | 70 | u_int32_t ass[4]; /* Argument save space for o32. */ |
fa807ff6 | 71 | u_int32_t trampoline[2]; |
8662eb14 | 72 | struct sigcontext sigctx; |
cc3c24ed | 73 | } *rt_ = context->cfa; |
8662eb14 AM |
74 | sc = &rt_->sigctx; |
75 | } | |
fa807ff6 RS |
76 | else |
77 | #endif | |
78 | if (pc[0] == (0x24020000 | __NR_rt_sigreturn)) | |
8662eb14 AM |
79 | { |
80 | struct rt_sigframe { | |
cc3c24ed | 81 | u_int32_t ass[4]; /* Argument save space for o32. */ |
fa807ff6 | 82 | u_int32_t trampoline[2]; |
1bde7dab | 83 | siginfo_t info; |
8662eb14 | 84 | _sig_ucontext_t uc; |
cc3c24ed | 85 | } *rt_ = context->cfa; |
8662eb14 AM |
86 | sc = &rt_->uc.uc_mcontext; |
87 | } | |
88 | else | |
89 | return _URC_END_OF_STACK; | |
90 | ||
25127042 | 91 | new_cfa = (_Unwind_Ptr) sc; |
6673f90b | 92 | fs->regs.cfa_how = CFA_REG_OFFSET; |
53d68b9f | 93 | fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__; |
6673f90b | 94 | fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa; |
8662eb14 | 95 | |
d04b77ac DJ |
96 | /* On o32 Linux, the register save slots in the sigcontext are |
97 | eight bytes. We need the lower half of each register slot, | |
98 | so slide our view of the structure back four bytes. */ | |
25127042 DD |
99 | #if _MIPS_SIM == _ABIO32 && defined __MIPSEB__ |
100 | reg_offset = 4; | |
101 | #else | |
102 | reg_offset = 0; | |
d04b77ac DJ |
103 | #endif |
104 | ||
8662eb14 AM |
105 | for (i = 0; i < 32; i++) { |
106 | fs->regs.reg[i].how = REG_SAVED_OFFSET; | |
107 | fs->regs.reg[i].loc.offset | |
25127042 | 108 | = (_Unwind_Ptr)&(sc->sc_regs[i]) + reg_offset - new_cfa; |
8662eb14 | 109 | } |
57972505 RS |
110 | /* "PC & -2" points to the faulting instruction, but the unwind code |
111 | searches for "(ADDR & -2) - 1". (See MASK_RETURN_ADDR for the source | |
112 | of the -2 mask.) Adding 2 here ensures that "(ADDR & -2) - 1" is the | |
113 | address of the second byte of the faulting instruction. | |
114 | ||
115 | Note that setting fs->signal_frame would not work. As the comment | |
116 | above MASK_RETURN_ADDR explains, MIPS unwinders must earch for an | |
117 | odd-valued address. */ | |
53d68b9f JM |
118 | fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how |
119 | = REG_SAVED_VAL_OFFSET; | |
120 | fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset | |
57972505 | 121 | = (_Unwind_Ptr)(sc->sc_pc) + 2 - new_cfa; |
53d68b9f | 122 | fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__; |
8662eb14 AM |
123 | |
124 | return _URC_NO_REASON; | |
125 | } | |
126 | #endif |