1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * S I G T R A M P *
6 * *
7 * Asm Implementation File *
8 * *
9 * Copyright (C) 2011-2023, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. *
17 * *
18 * As a special exception under Section 7 of GPL version 3, you are granted *
19 * additional permissions described in the GCC Runtime Library Exception, *
20 * version 3.1, as published by the Free Software Foundation. *
21 * *
22 * In particular, you can freely distribute your programs built with the *
23 * GNAT Pro compiler, including any required library run-time units, using *
24 * any licensing terms of your choosing. See the AdaCore Software License *
25 * for full details. *
26 * *
27 * GNAT was originally developed by the GNAT team at New York University. *
28 * Extensive contributions were provided by Ada Core Technologies Inc. *
29 * *
30 ****************************************************************************/
31
32 /**************************************************
33 * VxWorks version of the __gnat_sigtramp service *
34 **************************************************/
35
36 #include "sigtramp.h"
37 /* See sigtramp.h for a general explanation of functionality. */
38
39 #include <vxWorks.h>
40 #include <arch/../regs.h>
41 #ifndef __RTP__
42 #if defined(__i386__)
43 #include <version.h>
44 #endif
45 #include <sigLib.h>
46 #else
47 #include <signal.h>
48 #include <regs.h>
49
50 typedef struct mcontext
51 {
52 REG_SET regs;
53 } mcontext_t;
54
55 typedef struct ucontext
56 {
57 mcontext_t uc_mcontext; /* register set */
58 struct ucontext * uc_link; /* not used */
59 sigset_t uc_sigmask; /* set of signals blocked */
60 stack_t uc_stack; /* stack of context signaled */
61 } ucontext_t;
62 #endif
63
64 /* ----------------------
65 -- General comments --
66 ----------------------
67
68 Stubs are generated from toplevel asms and .cfi directives, much simpler
69 to use and check for correctness than manual encodings of CFI byte
70 sequences. The general idea is to establish CFA as sigcontext->sc_pregs
71 (for DKM) and mcontext (for RTP) and state where to find the registers as
72 offsets from there.
73
74 As of today, we support a stub providing CFI info for common
75 registers (GPRs, LR, ...). We might need variants with support for floating
76 point or altivec registers as well at some point.
77
78 Checking which variant should apply and getting at sc_pregs / mcontext
79 is simpler to express in C (we can't use offsetof in toplevel asms and
80 hardcoding constants is not workable with the flurry of VxWorks variants),
81 so this is the choice for our toplevel interface.
82
83 Note that the registers we "restore" here are those to which we have
84 direct access through the system sigcontext structure, which includes
85 only a partial set of the non-volatiles ABI-wise. */
86
87 /* -------------------------------------------
88 -- Prototypes for our internal asm stubs --
89 -------------------------------------------
90
91 Eventhough our symbols will remain local, the prototype claims "extern"
92 and not "static" to prevent compiler complaints about a symbol used but
93 never defined. */
94
95 #define TRAMP_COMMON __gnat_sigtramp_common
96
97 /* sigtramp stub providing CFI info for common registers. */
98
99 extern void
100 TRAMP_COMMON (int signo, void *siginfo, void *sigcontext,
101 __sigtramphandler_t * handler, REG_SET * sc_pregs);
102
103 /* -------------------------------------
104 -- Common interface implementation --
105 -------------------------------------
106
107 We enforce optimization to minimize the overhead of the extra layer. */
108
109 #if defined(__vxworks) && (defined (__i386__) || defined (__x86_64__)) && !defined (VTHREADS)
110 static int __gnat_is_vxsim = 0;
111
112 void __gnat_set_is_vxsim(int val) {
113 __gnat_is_vxsim = val;
114 }
115 #endif
116
117 void __gnat_sigtramp (int signo, void *si, void *sc,
118 __sigtramphandler_t * handler)
119 __attribute__((optimize(2)));
120
121 void __gnat_sigtramp (int signo, void *si, void *sc,
122 __sigtramphandler_t * handler)
123 {
124 REG_SET *pregs;
125
126 /* VXSIM uses a different signal context structure than the regular x86
127 targets:
128 * on x86-vx6: two 32-bit values are added at the end of the REG_SET, plus
129 an explicit padding of 0xc8 characters (200 characters). The sigcontext
130 containing a complete REG_SET just before the field 'sc_pregs', this
131 adds a 208 bytes offset to get the value of 'sc_pregs'.
132 * on x86-vx7: the same offset is used on vx7: 3 32-bit values are present
133 at the end of the reg set, but the padding is then of 0xc4 characters.
134 * on x86_64-vx7: two 64-bit values are added at the beginning of the
135 REG_SET. This adds a 16 bytes offset to get the value of 'sc_pregs',
136 and another 16 bytes offset within the pregs structure to retrieve the
137 registers list.
138
139 * See header file regsSimlinux.h.
140 */
141
142 /* Retrieve the registers to restore : */
143 #ifndef __RTP__
144 #ifdef __HANDLE_VXSIM_SC
145 #if defined(__i386__)
146 /* move sctx 208 bytes further, so that the vxsim's sc_pregs field coincide
147 with the expected x86 one */
148 struct sigcontext * sctx =
149 (struct sigcontext *) (sc + (__gnat_is_vxsim ?
150 (_WRS_VXWORKS_MAJOR == 7 ? 204 : 208)
151 : 0));
152 #elif defined(__x86_64__)
153 /* move sctx 16 bytes further, so that the vxsim's sc_pregs field coincide
154 with the expected x86_64 one */
155 struct sigcontext * sctx =
156 (struct sigcontext *) (sc + (__gnat_is_vxsim ? 16 : 0));
157 #endif /* __i386__ || __x86_64__ */
158 #else /* __HANDLE_VXSIM_SC__ */
159 struct sigcontext * sctx = (struct sigcontext *) sc;
160 #endif
161
162 pregs = sctx->sc_pregs;
163
164 #else /* !defined(__RTP__) */
165
166 mcontext_t *mcontext = &((ucontext_t *) sc)->uc_mcontext;
167 /* No specific offset in this case for vxsim */
168 pregs = &(mcontext->regs);
169
170 #endif /* !defined(__RTP__) */
171
172 #if defined (__HANDLE_VXSIM_SC) && defined (__x86_64__)
173 /* Ignore the first two values, that are not registers in case of
174 vxsim */
175 pregs = (REG_SET *) ((void *)pregs + (__gnat_is_vxsim ? 16 : 0));
176 #endif
177
178 /* And now call the real signal trampoline with the list of registers */
179 __gnat_sigtramp_common (signo, si, sc, handler, pregs);
180 }
181
182 /* Include the target specific bits. */
183 #include "sigtramp-vxworks-target.h"
184
185 /* sigtramp stub for common registers. */
186
187 asm (SIGTRAMP_START(TRAMP_COMMON));
188 asm (CFI_DEF_CFA);
189 asm (CFI_COMMON_REGS);
190 asm (SIGTRAMP_BODY);
191 asm (SIGTRAMP_END(TRAMP_COMMON));