comment/style fixes
[official-gcc.git] / libjava / include / x86_64-signal.h
blob4bd8a360115e1b404027a5c57b69ffba674c8eb0
1 // x86_64-signal.h - Catch runtime signals and turn them into exceptions
2 // on an x86_64 based GNU/Linux system.
4 /* Copyright (C) 2003, 2006, 2007 Free Software Foundation
6 This file is part of libgcj.
8 This software is copyrighted work licensed under the terms of the
9 Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
10 details. */
13 #ifdef __x86_64__
15 #ifndef JAVA_SIGNAL_H
16 #define JAVA_SIGNAL_H 1
18 #include <signal.h>
19 #include <sys/syscall.h>
21 #define HANDLE_SEGV 1
22 #define HANDLE_FPE 1
24 #define SIGNAL_HANDLER(_name) \
25 static void _Jv_##_name (int, siginfo_t *, \
26 void *_p __attribute__ ((__unused__)))
28 #define HANDLE_DIVIDE_OVERFLOW \
29 do \
30 { \
31 struct ucontext *_uc = (struct ucontext *)_p; \
32 gregset_t &_gregs = _uc->uc_mcontext.gregs; \
33 unsigned char *_rip = (unsigned char *)_gregs[REG_RIP]; \
35 /* According to the JVM spec, "if the dividend is the negative \
36 * integer of largest possible magnitude for the type and the \
37 * divisor is -1, then overflow occurs and the result is equal to \
38 * the dividend. Despite the overflow, no exception occurs". \
40 * We handle this by inspecting the instruction which generated the \
41 * signal and advancing ip to point to the following instruction. \
42 * As the instructions are variable length it is necessary to do a \
43 * little calculation to figure out where the following instruction \
44 * actually is. \
46 */ \
48 bool _is_64_bit = false; \
50 if ((_rip[0] & 0xf0) == 0x40) /* REX byte present. */ \
51 { \
52 unsigned char _rex = _rip[0] & 0x0f; \
53 _is_64_bit = (_rex & 0x08) != 0; \
54 _rip++; \
55 } \
57 /* Detect a signed division of Integer.MIN_VALUE or Long.MIN_VALUE. */ \
58 if (_rip[0] == 0xf7) \
59 { \
60 bool _min_value_dividend = false; \
61 unsigned char _modrm = _rip[1]; \
63 if (((_modrm >> 3) & 7) == 7) \
64 { \
65 if (_is_64_bit) \
66 _min_value_dividend = \
67 _gregs[REG_RAX] == (greg_t)0x8000000000000000UL; \
68 else \
69 _min_value_dividend = \
70 (_gregs[REG_RAX] & 0xffffffff) == (greg_t)0x80000000UL; \
71 } \
73 if (_min_value_dividend) \
74 { \
75 unsigned char _rm = _modrm & 7; \
76 _gregs[REG_RDX] = 0; /* the remainder is zero */ \
77 switch (_modrm >> 6) \
78 { \
79 case 0: /* register indirect */ \
80 if (_rm == 5) /* 32-bit displacement */ \
81 _rip += 4; \
82 if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
83 _rip += 1; \
84 break; \
85 case 1: /* register indirect + 8-bit displacement */ \
86 _rip += 1; \
87 if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
88 _rip += 1; \
89 break; \
90 case 2: /* register indirect + 32-bit displacement */ \
91 _rip += 4; \
92 if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
93 _rip += 1; \
94 break; \
95 case 3: \
96 break; \
97 } \
98 _rip += 2; \
99 _gregs[REG_RIP] = (greg_t)_rip; \
100 return; \
104 while (0)
106 extern "C"
108 struct kernel_sigaction
110 void (*k_sa_sigaction)(int,siginfo_t *,void *);
111 unsigned long k_sa_flags;
112 void (*k_sa_restorer) (void);
113 sigset_t k_sa_mask;
117 #define MAKE_THROW_FRAME(_exception)
119 #define RESTORE(name, syscall) RESTORE2 (name, syscall)
120 #define RESTORE2(name, syscall) \
121 asm \
123 ".text\n" \
124 ".byte 0 # Yes, this really is necessary\n" \
125 ".align 16\n" \
126 "__" #name ":\n" \
127 " movq $" #syscall ", %rax\n" \
128 " syscall\n" \
131 /* The return code for realtime-signals. */
132 RESTORE (restore_rt, __NR_rt_sigreturn)
133 void restore_rt (void) asm ("__restore_rt")
134 __attribute__ ((visibility ("hidden")));
136 #define INIT_SEGV \
137 do \
139 struct kernel_sigaction act; \
140 act.k_sa_sigaction = _Jv_catch_segv; \
141 sigemptyset (&act.k_sa_mask); \
142 act.k_sa_flags = SA_SIGINFO|0x4000000; \
143 act.k_sa_restorer = restore_rt; \
144 syscall (SYS_rt_sigaction, SIGSEGV, &act, NULL, _NSIG / 8); \
146 while (0)
148 #define INIT_FPE \
149 do \
151 struct kernel_sigaction act; \
152 act.k_sa_sigaction = _Jv_catch_fpe; \
153 sigemptyset (&act.k_sa_mask); \
154 act.k_sa_flags = SA_SIGINFO|0x4000000; \
155 act.k_sa_restorer = restore_rt; \
156 syscall (SYS_rt_sigaction, SIGFPE, &act, NULL, _NSIG / 8); \
158 while (0)
160 /* You might wonder why we use syscall(SYS_sigaction) in INIT_FPE
161 * instead of the standard sigaction(). This is necessary because of
162 * the shenanigans above where we increment the PC saved in the
163 * context and then return. This trick will only work when we are
164 * called _directly_ by the kernel, because linuxthreads wraps signal
165 * handlers and its wrappers do not copy the sigcontext struct back
166 * when returning from a signal handler. If we return from our divide
167 * handler to a linuxthreads wrapper, we will lose the PC adjustment
168 * we made and return to the faulting instruction again. Using
169 * syscall(SYS_sigaction) causes our handler to be called directly
170 * by the kernel, bypassing any wrappers. */
172 #endif /* JAVA_SIGNAL_H */
174 #else /* __x86_64__ */
176 /* This is for the 32-bit subsystem on x86-64. */
178 #define sigcontext_struct sigcontext
179 #include <java-signal-aux.h>
181 #endif /* __x86_64__ */