1 /* DWARF2 EH unwinding support for TPF OS.
2 Copyright (C) 2004-2023 Free Software Foundation, Inc.
3 Contributed by P.J. Darcy (darcypj@us.ibm.com).
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 #include <dlfcn.h>
27 #include <stdbool.h>
28
29 /* Function Name: __isPATrange
30 Parameters passed into it: address to check
31 Return Value: A 1 if address is in pat code "range", 0 if not
32 Description: This function simply checks to see if the address
33 passed to it is in the CP pat code range. */
34
35 #define CP_CNF 0x000000000000c18u /* location of BSS CINFC pointer */
36 #define cinfc_fast(TAG) (void *) \
37 *((unsigned long *) *(unsigned long *) (CP_CNF) + (TAG))
38 #define CINFC_CMRESET 187
39 #define CINTFC_CMCENBKST 431
40 #define CINTFC_CMCENBKED 432
41
42 static inline unsigned int
43 __isPATrange (void *addr)
44 {
45 return !!(addr > cinfc_fast (CINTFC_CMCENBKST)
46 && addr < cinfc_fast (CINTFC_CMCENBKED));
47 }
48
49 static inline unsigned int
50 __isSkipResetAddr (void *addr)
51 {
52 return !!(addr == cinfc_fast (CINFC_CMRESET));
53 }
54
55 /* TPF return address offset from start of stack frame. */
56 #define ICST_CRET 168
57 #define ICST_SRET 320
58
59 /* Exceptions macro defined for TPF so that functions without
60 dwarf frame information can be used with exceptions. */
61 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
62
63 static _Unwind_Reason_Code
64 s390_fallback_frame_state (struct _Unwind_Context *context,
65 _Unwind_FrameState *fs)
66 {
67 unsigned long int regs;
68 unsigned long int new_cfa;
69 int i;
70
71 regs = *((unsigned long int *)
72 (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
73
74 /* Are we going through special linkage code? */
75 if (__isPATrange (context->ra) || __isSkipResetAddr (context->ra))
76 {
77
78 /* Our return register isn't zero for end of stack, so
79 check backward stackpointer to see if it is zero. */
80 if (regs == 0)
81 return _URC_END_OF_STACK;
82
83 /* No stack frame. */
84 fs->regs.cfa_how = CFA_REG_OFFSET;
85 fs->regs.cfa_reg = 15;
86 fs->regs.cfa_offset = STACK_POINTER_OFFSET;
87
88 /* All registers remain unchanged ... */
89 for (i = 0; i < 32; i++)
90 {
91 fs->regs.how[i] = REG_SAVED_REG;
92 fs->regs.reg[i].loc.reg = i;
93 }
94
95 /* ... except for %r14, which is stored at CFA+offset where offset
96 is displacment of ICST_CRET or ICST_SRET from CFA */
97 if ( __isPATrange(context->ra) ) {
98 fs->regs.how[14] = REG_SAVED_OFFSET;
99 fs->regs.reg[14].loc.offset = ICST_CRET - STACK_POINTER_OFFSET;
100 fs->retaddr_column = 14;
101 } else {
102 fs->regs.how[14] = REG_SAVED_OFFSET;
103 fs->regs.reg[14].loc.offset = ICST_SRET - STACK_POINTER_OFFSET;
104 fs->retaddr_column = 14;
105
106 }
107
108 return _URC_NO_REASON;
109 }
110
111 regs = *((unsigned long int *)
112 (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
113 new_cfa = regs + STACK_POINTER_OFFSET;
114
115 fs->regs.cfa_how = CFA_REG_OFFSET;
116 fs->regs.cfa_reg = 15;
117 fs->regs.cfa_offset = new_cfa -
118 (unsigned long int) context->cfa + STACK_POINTER_OFFSET;
119
120 for (i = 0; i < 16; i++)
121 {
122 fs->regs.how[i] = REG_SAVED_OFFSET;
123 fs->regs.reg[i].loc.offset = regs + i*8 - new_cfa;
124 }
125
126 for (i = 0; i < 4; i++)
127 {
128 fs->regs.how[16 + i] = REG_SAVED_OFFSET;
129 fs->regs.reg[16 + i].loc.offset = regs + 16*8 + i*8 - new_cfa;
130 }
131
132 fs->retaddr_column = 14;
133
134 return _URC_NO_REASON;
135 }
136
137 /* Function Name: __tpf_eh_return
138 Parameters passed into it: Destination address to jump to.
139 Return Value: Converted Destination address if a Pat Stub exists.
140 Description: This function swaps the unwinding return address
141 with the cp stub code. The original target return address is
142 then stored into the tpf return address field. The cp stub
143 code is searched for by climbing back up the stack and
144 comparing the tpf stored return address object address to
145 that of the targets object address. */
146
147 #define CURRENT_STACK_PTR() \
148 ({ register unsigned long int *stack_ptr asm ("%r15"); stack_ptr; })
149
150 #define PREVIOUS_STACK_PTR() \
151 ((unsigned long int *)(*(CURRENT_STACK_PTR())))
152
153 #define RA_OFFSET 112
154 #define R15_OFFSET 120
155 #define TPFAREA_OFFSET 160
156 #define TPFAREA_SIZE STACK_POINTER_OFFSET-TPFAREA_OFFSET
157 #define INVALID_RETURN 0
158
159 #define LOWCORE_PAGE3_ADDR 4032
160 #define PG3_SKIPPING_OFFSET 18
161
162 void * __tpf_eh_return (void *target, void *origRA);
163
164 void *
165 __tpf_eh_return (void *target, void *origRA)
166 {
167 Dl_info targetcodeInfo, currentcodeInfo;
168 int retval;
169 void *current, *stackptr, *destination_frame;
170 unsigned char *skipFlagAddress;
171 unsigned long int shifter;
172 bool is_a_stub;
173
174 is_a_stub = false;
175
176 /* Get code info for target return's address. */
177 retval = dladdr (target, &targetcodeInfo);
178
179 /* Ensure the code info is valid (for target). */
180 if (retval != INVALID_RETURN)
181 {
182 /* Begin climbing stack searching for target address. */
183 stackptr = (void *) *(CURRENT_STACK_PTR());
184
185 /* Get return address based on our stackptr. */
186 current = (void *) *(unsigned long *) (stackptr + RA_OFFSET);
187
188 /* Is current return address our initiating exception stack
189 frame? If not, climb the stack one more frame. */
190 if (current != origRA) {
191 stackptr = (void *) *(unsigned long *) stackptr;
192 }
193
194 /* Begin looping through stack frames. Stop if invalid
195 code information is retrieved or if a match between the
196 current stack frame iteration shared object's address
197 matches that of the target, calculated above. */
198 do
199 {
200 /* Get return address based on our stackptr iterator. */
201 current = (void *) *(unsigned long *) (stackptr + RA_OFFSET);
202
203 /* Is it a Pat Stub? */
204 if (__isPATrange (current)
205 || (__isSkipResetAddr (current)
206 && __isPATrange ((void *) *(unsigned long *) (stackptr
207 + ICST_SRET))))
208 {
209 /* Yes it was, get real return address in TPF stack area. */
210 current = (void *) *(unsigned long *) (stackptr + ICST_CRET);
211 is_a_stub = true;
212 }
213
214 /* Get codeinfo on RA so that we can figure out
215 the module address. */
216 retval = dladdr (current, ¤tcodeInfo);
217
218 /* Check that codeinfo for current stack frame is valid.
219 Then compare the module address of current stack frame
220 to target stack frame to determine if we have the pat
221 stub address we want. Also ensure we are dealing
222 with a module crossing, stub return address. */
223 if (is_a_stub && retval != INVALID_RETURN
224 && targetcodeInfo.dli_fbase == currentcodeInfo.dli_fbase)
225 {
226 /* Yes! They are in the same module.
227 Force copy of TPF private stack area to
228 destination stack frame TPF private area. */
229 destination_frame = (void *) *((unsigned long int *)
230 (*PREVIOUS_STACK_PTR() + R15_OFFSET));
231
232 /* Copy TPF linkage area from current frame to
233 destination frame. */
234 memcpy((void *) (destination_frame + TPFAREA_OFFSET),
235 (void *) (stackptr + TPFAREA_OFFSET), TPFAREA_SIZE);
236
237 /* Now overlay the
238 real target address into the TPF stack area of
239 the target frame we are jumping to. */
240 *(unsigned long *) (destination_frame + ICST_CRET) =
241 (unsigned long) target;
242
243 /* Before returning the desired pat stub address to
244 the exception handling unwinder so that it can
245 actually do the "leap" shift out the low order
246 bit designated to determine if we are in 64BIT mode.
247 This is necessary for CTOA stubs.
248 Otherwise we leap one byte past where we want to
249 go to in the TPF pat stub linkage code. */
250 shifter = *(unsigned long *) (stackptr + RA_OFFSET);
251
252 shifter &= ~1ul;
253
254 /* Store Pat Stub Address in destination Stack Frame. */
255 *((unsigned long int *) (destination_frame +
256 RA_OFFSET)) = shifter;
257
258 /* Re-adjust pat stub address to go to correct place
259 in linkage. */
260 shifter = shifter - 4;
261
262 /* Reset the Function Trace Skipping Switch to re-enable */
263 /* recording Trace entries if it was turned off. */
264 skipFlagAddress =
265 (unsigned char *) *(unsigned long *) LOWCORE_PAGE3_ADDR;
266 skipFlagAddress += PG3_SKIPPING_OFFSET;
267 *skipFlagAddress = '\x00';
268
269 return (void *) shifter;
270 }
271
272 /* Desired module pat stub not found ...
273 Bump stack frame iterator. */
274 stackptr = (void *) *(unsigned long int *) stackptr;
275
276 is_a_stub = false;
277
278 } while (stackptr && retval != INVALID_RETURN
279 && targetcodeInfo.dli_fbase != currentcodeInfo.dli_fbase);
280 }
281
282 /* Reset the Function Trace Skipping Switch to re-enable */
283 /* recording Trace entries if it was turned off. */
284 skipFlagAddress = (unsigned char *) *(unsigned long *) LOWCORE_PAGE3_ADDR;
285 skipFlagAddress += PG3_SKIPPING_OFFSET;
286 *skipFlagAddress = '\x00';
287
288 /* No pat stub found, could be a problem? Simply return unmodified
289 target address. */
290 return target;
291 }