-// i386-signal.h - Catch runtime signals and turn them into exceptions.
+// i386-signal.h - Catch runtime signals and turn them into exceptions
+// on an i386 based Linux system.
-/* Copyright (C) 1998, 1999, 2001 Free Software Foundation
+/* Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation
This file is part of libgcj.
Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
details. */
-/* This technique should work for all i386 based Unices which conform
- * to iBCS2. This includes all versions of Linux more recent than 1.3
- */
-
#ifndef JAVA_SIGNAL_H
#define JAVA_SIGNAL_H 1
#define HANDLE_FPE 1
#define SIGNAL_HANDLER(_name) \
-static void _name (int _dummy)
+static void _name (int _dummy __attribute__ ((__unused__)))
#define MAKE_THROW_FRAME(_exception) \
do \
{ \
void **_p = (void **)&_dummy; \
- struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p; \
+ volatile struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p; \
\
/* Advance the program counter so that it is after the start of the \
instruction: the x86 exception handler expects \
do \
{ \
void **_p = (void **)&_dummy; \
- struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p; \
+ volatile struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p;\
\
- register unsigned long *_ebp = (unsigned long *)_regs->ebp; \
register unsigned char *_eip = (unsigned char *)_regs->eip; \
\
/* According to the JVM spec, "if the dividend is the negative \
if (_regs->eax == 0x80000000 \
&& ((_modrm >> 3) & 7) == 7) /* Signed divide */ \
{ \
+ unsigned char _rm = _modrm & 7; \
_regs->edx = 0; /* the remainder is zero */ \
switch (_modrm >> 6) \
{ \
- case 0: \
- if ((_modrm & 7) == 5) \
- _eip += 4; \
+ case 0: /* register indirect */ \
+ if (_rm == 5) /* 32-bit displacement */ \
+ _eip += 4; \
+ if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
+ _eip += 1; \
break; \
- case 1: \
+ case 1: /* register indirect + 8-bit displacement */ \
_eip += 1; \
+ if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
+ _eip += 1; \
break; \
- case 2: \
+ case 2: /* register indirect + 32-bit displacement */ \
_eip += 4; \
+ if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \
+ _eip += 1; \
break; \
case 3: \
break; \
} \
while (0)
-#define INIT_SEGV \
-do \
- { \
- nullp = new java::lang::NullPointerException (); \
- struct sigaction act; \
- act.sa_handler = catch_segv; \
- sigemptyset (&act.sa_mask); \
- act.sa_flags = 0; \
- syscall (SYS_sigaction, SIGSEGV, &act, NULL); \
- } \
+/* We use old_kernel_sigaction here because we're calling the kernel
+ directly rather than via glibc. The sigaction structure that the
+ syscall uses is a different shape from the one in userland and not
+ visible to us in a header file so we define it here. */
+
+struct old_i386_kernel_sigaction {
+ void (*k_sa_handler) (int);
+ unsigned long k_sa_mask;
+ unsigned long k_sa_flags;
+ void (*sa_restorer) (void);
+};
+
+#define RESTORE(name, syscall) RESTORE2 (name, syscall)
+# define RESTORE2(name, syscall) \
+asm \
+ ( \
+ ".text\n" \
+ ".byte 0 # Yes, this really is necessary\n" \
+ " .align 8\n" \
+ "__" #name ":\n" \
+ " popl %eax\n" \
+ " movl $" #syscall ", %eax\n" \
+ " int $0x80" \
+ );
+
+RESTORE (restore, __NR_sigreturn)
+static void restore (void) asm ("__restore");
+
+#define INIT_SEGV \
+do \
+ { \
+ struct old_i386_kernel_sigaction kact; \
+ kact.k_sa_handler = catch_segv; \
+ kact.k_sa_mask = 0; \
+ kact.k_sa_flags = 0x4000000; \
+ kact.sa_restorer = restore; \
+ syscall (SYS_sigaction, SIGSEGV, &kact, NULL); \
+ } \
while (0)
-#define INIT_FPE \
-do \
- { \
- arithexception = new java::lang::ArithmeticException \
- (JvNewStringLatin1 ("/ by zero")); \
- struct sigaction act; \
- act.sa_handler = catch_fpe; \
- sigemptyset (&act.sa_mask); \
- act.sa_flags = 0; \
- syscall (SYS_sigaction, SIGFPE, &act, NULL); \
- } \
+#define INIT_FPE \
+do \
+ { \
+ struct old_i386_kernel_sigaction kact; \
+ kact.k_sa_handler = catch_fpe; \
+ kact.k_sa_mask = 0; \
+ kact.k_sa_flags = 0x4000000; \
+ kact.sa_restorer = restore; \
+ syscall (SYS_sigaction, SIGFPE, &kact, NULL); \
+ } \
while (0)
/* You might wonder why we use syscall(SYS_sigaction) in INIT_FPE
* when returning from a signal handler. If we return from our divide
* handler to a linuxthreads wrapper, we will lose the PC adjustment
* we made and return to the faulting instruction again. Using
- * syscall(SYS_sigaction) causes our handler to be called directly by
- * the kernel, bypassing any wrappers. This is a kludge, and a future
- * version of this handler will do something better. */
+ * syscall(SYS_sigaction) causes our handler to be called directly
+ * by the kernel, bypassing any wrappers.
+
+ * Also, there is at the present time no unwind info in the
+ * linuxthreads library's signal handlers and so we can't unwind
+ * through them anyway. */
#endif /* JAVA_SIGNAL_H */