1 /* DWARF2 EH unwinding support for AIX.
2 Copyright (C) 2011-2023 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
15
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/>. */
24
25 /* Useful register numbers. */
26
27 #define R_LR 65
28 #define R_CR2 70
29 #define R_XER 76
30 #define R_FIRST_ALTIVEC 77
31 #define R_VRSAVE 109
32 #define R_VSCR 110
33
34 /* If the current unwind info (FS) does not contain explicit info
35 saving R2, then we have to do a minor amount of code reading to
36 figure out if it was saved. The big problem here is that the
37 code that does the save/restore is generated by the linker, so
38 we have no good way to determine at compile time what to do. */
39
40 #ifdef __64BIT__
41 #define MD_FROB_UPDATE_CONTEXT(CTX, FS) \
42 do { \
43 if ((FS)->regs.how[2] == REG_UNSAVED) \
44 { \
45 unsigned int *insn \
46 = (unsigned int *) \
47 _Unwind_GetGR ((CTX), R_LR); \
48 if (*insn == 0xE8410028) \
49 _Unwind_SetGRPtr ((CTX), 2, (CTX)->cfa + 40); \
50 } \
51 } while (0)
52 #else
53 #define MD_FROB_UPDATE_CONTEXT(CTX, FS) \
54 do { \
55 if ((FS)->regs.how[2] == REG_UNSAVED) \
56 { \
57 unsigned int *insn \
58 = (unsigned int *) \
59 _Unwind_GetGR ((CTX), R_LR); \
60 if (*insn == 0x80410014) \
61 _Unwind_SetGRPtr ((CTX), 2, (CTX)->cfa + 20); \
62 } \
63 } while (0)
64 #endif
65
66 /* Now on to MD_FALLBACK_FRAME_STATE_FOR.
67 32bit AIX 5.2, 5.3, 6.1, 7.X and
68 64bit AIX 6.1, 7.X only at this stage. */
69
70 #include <stdlib.h>
71 #include <stddef.h>
72 #include <signal.h>
73 #include <sys/machine.h>
74
75 #ifdef __64BIT__
76
77 typedef struct __context64 mstate_t;
78
79 #else
80
81 typedef struct mstsave mstate_t;
82
83 #endif
84
85 #define MD_FALLBACK_FRAME_STATE_FOR ppc_aix_fallback_frame_state
86
87 /* If we are compiling on AIX < 5.3, the VMX related datastructs are not
88 defined and we take measures to obtain proper runtime behavior if the
89 compiled code happens to run on a later version with VMX enabled. */
90
91 #ifndef MSR_VMX
92 #define MSR_VMX 0x2000000
93 #endif
94
95 typedef unsigned int uint;
96 typedef struct { uint v[4]; } vreg_t;
97 typedef struct {
98 vreg_t regs[32];
99 uint pad1 [3];
100 uint vscr;
101 uint vrsave;
102 uint pad2 [3];
103 } vstate_t;
104
105 #define EXT_CONTEXT_MARK 0x45435458
106 #define EXT_CONTEXT_SIZE 4096
107 #define BUMPER_SIZE (EXT_CONTEXT_SIZE - sizeof(vstate_t) - (5 * sizeof(int)))
108
109 typedef struct {
110 uint pad1 [4];
111 vstate_t vstate;
112 char bumper [BUMPER_SIZE];
113 int mark;
114 } extended_context_t;
115
116 typedef struct {
117 char bumper [offsetof (ucontext_t, uc_stack) + sizeof (stack_t)];
118 extended_context_t * ectx;
119 int mark;
120 } vmx_ucontext_t;
121
122 /* Determine whether CONTEXT designates a signal handler, and return the
123 associated ucontext_t address if so. Return NULL otherwise. */
124
125 static ucontext_t *
126 ucontext_for (struct _Unwind_Context *context)
127 {
128 const unsigned int * ra = context->ra;
129
130 /* AIX 5.2, 5.3, 6.1 and 7.X, threaded or not, share common patterns
131 and feature variants depending on the configured kernel (unix_mp
132 or unix_64). */
133
134 #ifdef __64BIT__
135 if (*(ra - 5) == 0x4c00012c /* isync */
136 && *(ra - 4) == 0xe8ec0000 /* ld r7,0(r12) */
137 && *(ra - 3) == 0xe84c0008 /* ld r2,8(r12) */
138 && *(ra - 2) == 0x7ce903a6 /* mtctr r7 */
139 && *(ra - 1) == 0x4e800421 /* bctrl */
140 && *(ra - 0) == 0x7de27b78) /* mr r2,r15 <-- context->ra */
141 {
142 /* unix_64 */
143 if (*(ra - 6) == 0x7d000164) /* mtmsrd r8 */
144 {
145 /* AIX 6.1, 7.1 and 7.2 */
146 return (ucontext_t *)(context->cfa + 0x70);
147 }
148 }
149 #else
150 if (*(ra - 5) == 0x4c00012c /* isync */
151 && *(ra - 4) == 0x80ec0000 /* lwz r7,0(r12) */
152 && *(ra - 3) == 0x804c0004 /* lwz r2,4(r12) */
153 && *(ra - 2) == 0x7ce903a6 /* mtctr r7 */
154 && *(ra - 1) == 0x4e800421 /* bctrl */
155 && *(ra - 0) == 0x7dc37378) /* mr r3,r14 <-- context->ra */
156 {
157 /* unix_64 */
158 if (*(ra - 6) == 0x7d000164) /* mtmsrd r8 */
159 {
160 switch (*(ra + 18))
161 {
162 /* AIX 5.2 */
163 case 0x835a0520: /* lwz r26,1312(r26) */
164 return (ucontext_t *)(context->cfa + 0x70);
165
166 /* AIX 5.3 */
167 case 0x835a0570: /* lwz r26,1392(r26) */
168 return (ucontext_t *)(context->cfa + 0x40);
169
170 /* AIX 6.1 and 7.1 */
171 case 0x2c1a0000: /* cmpwi r26,0 */
172 return (ucontext_t *)(context->cfa + 0x40);
173
174 /* AIX 7.2 */
175 case 0x3800000a: /* li r0,A */
176 return (ucontext_t *)(context->cfa + 0x40);
177
178 default:
179 return 0;
180 }
181 }
182
183 /* unix_mp */
184 if (*(ra - 6) == 0x7d000124) /* mtmsr r8 */
185 {
186 typedef struct {
187 char pad[56];
188 ucontext_t ucontext;
189 siginfo_t siginfo;
190 } aix52_stack_t;
191
192 aix52_stack_t * frame = (aix52_stack_t *) context->cfa;
193 return &frame->ucontext;
194 }
195 }
196 #endif
197 return 0;
198 }
199
200 /* The fallback proper. */
201
202 #ifdef __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
203 #define RETURN_COLUMN __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
204 #else
205 #define RETURN_COLUMN ARG_POINTER_REGNUM
206 #endif
207
208 #define REGISTER_CFA_OFFSET_FOR(FS,REGNO,ADDR,CFA)\
209 do { \
210 (FS)->regs.how[REGNO] = REG_SAVED_OFFSET; \
211 (FS)->regs.reg[REGNO].loc.offset = (long) (ADDR) - (CFA); \
212 } while (0)
213
214 static _Unwind_Reason_Code
215 ppc_aix_fallback_frame_state (struct _Unwind_Context *context,
216 _Unwind_FrameState *fs)
217 {
218 ucontext_t * uctx = ucontext_for (context);
219 mstate_t * mctx;
220
221 long new_cfa;
222 int i;
223
224 if (uctx == NULL)
225 return _URC_END_OF_STACK;
226
227 mctx = &uctx->uc_mcontext.jmp_context;
228
229 /* The "kernel" frame cfa is the stack pointer at the signal occurrence
230 point. */
231 new_cfa = mctx->gpr[__LIBGCC_STACK_POINTER_REGNUM__];
232
233 fs->regs.cfa_how = CFA_REG_OFFSET;
234 fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
235 fs->regs.cfa_offset = new_cfa - (long) context->cfa;
236
237 /* And we state how to find the various registers it has saved with
238 relative offset rules from there. */
239
240 for (i = 0; i < 32; i++)
241 if (i != __LIBGCC_STACK_POINTER_REGNUM__)
242 REGISTER_CFA_OFFSET_FOR (fs, i, &mctx->gpr[i], new_cfa);
243
244 REGISTER_CFA_OFFSET_FOR (fs, R_CR2, &mctx->cr, new_cfa);
245 REGISTER_CFA_OFFSET_FOR (fs, R_XER, &mctx->xer, new_cfa);
246 REGISTER_CFA_OFFSET_FOR (fs, R_LR, &mctx->lr, new_cfa);
247
248 fs->retaddr_column = RETURN_COLUMN;
249 REGISTER_CFA_OFFSET_FOR (fs, RETURN_COLUMN, &mctx->iar, new_cfa);
250 fs->signal_frame = 1;
251
252 /* Honor FP Ever Used ... */
253 if (mctx->fpeu)
254 {
255 for (i = 0; i < 32; i++)
256 REGISTER_CFA_OFFSET_FOR (fs, i+32, &mctx->fpr[i], new_cfa);
257 }
258
259 /* Honor VMX context, if any. We expect the msr bit never to be set in
260 environments where there is no VMX support, e.g. on AIX < 5.3. */
261 if (mctx->msr & MSR_VMX)
262 {
263 vmx_ucontext_t * uc = (vmx_ucontext_t *) uctx;
264
265 if (uc->mark == EXT_CONTEXT_MARK && uc->ectx->mark == EXT_CONTEXT_MARK)
266 {
267 vstate_t * vstate = &uc->ectx->vstate;
268
269 for (i = 0; i < 32; i++)
270 REGISTER_CFA_OFFSET_FOR
271 (fs, i+R_FIRST_ALTIVEC, &vstate->regs[i], new_cfa);
272
273 REGISTER_CFA_OFFSET_FOR (fs, R_VSCR, &vstate->vscr, new_cfa);
274 REGISTER_CFA_OFFSET_FOR (fs, R_VRSAVE, &vstate->vrsave, new_cfa);
275 }
276 }
277
278 return _URC_NO_REASON;
279 }