From 70f661cc0a35e91f85eff27d0618dcfec06bdfe3 Mon Sep 17 00:00:00 2001 From: aph Date: Mon, 10 Apr 2006 16:01:23 +0000 Subject: [PATCH] 2006-04-10 Andrew Haley * include/x86_64-signal.h (HANDLE_DIVIDE_OVERFLOW): New. (SIGNAL_HANDLER): Mark arg as unused. * configure.host (x86_64-* DIVIDESPEC): Use fno-use-divide-subroutine. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@112827 138bc75d-0d04-0410-961f-82ee72b054a4 --- libjava/ChangeLog | 7 +++ libjava/configure.host | 2 +- libjava/include/x86_64-signal.h | 114 ++++++++++++++++++++++++++++++++++++---- 3 files changed, 113 insertions(+), 10 deletions(-) diff --git a/libjava/ChangeLog b/libjava/ChangeLog index d52d8ab8c3f..2117abfe777 100644 --- a/libjava/ChangeLog +++ b/libjava/ChangeLog @@ -1,3 +1,10 @@ +2006-04-10 Andrew Haley + + * include/x86_64-signal.h (HANDLE_DIVIDE_OVERFLOW): New. + (SIGNAL_HANDLER): Mark arg as unused. + * configure.host (x86_64-* DIVIDESPEC): Use + fno-use-divide-subroutine. + 2006-04-07 Andrew Haley * java/net/InetAddress.java: Throw an UnknownHostException if diff --git a/libjava/configure.host b/libjava/configure.host index 108f3a2c01f..e21307258f4 100644 --- a/libjava/configure.host +++ b/libjava/configure.host @@ -115,7 +115,7 @@ case "${host}" in libgcj_flags="${libgcj_flags} -fomit-frame-pointer" libgcj_cxxflags= libgcj_cflags= - DIVIDESPEC=-f%{m32:no-}use-divide-subroutine + DIVIDESPEC=-fno-use-divide-subroutine enable_hash_synchronization_default=yes slow_pthread_self=yes libgcj_interpreter=yes diff --git a/libjava/include/x86_64-signal.h b/libjava/include/x86_64-signal.h index b4b4c2b988c..479be3ff898 100644 --- a/libjava/include/x86_64-signal.h +++ b/libjava/include/x86_64-signal.h @@ -19,9 +19,88 @@ details. */ #include #define HANDLE_SEGV 1 - -#define SIGNAL_HANDLER(_name) \ -static void _Jv_##_name (int, siginfo_t *, void *_p) +#define HANDLE_FPE 1 + +#define SIGNAL_HANDLER(_name) \ +static void _Jv_##_name (int, siginfo_t *, \ + void *_p __attribute__ ((__unused__))) + +#define HANDLE_DIVIDE_OVERFLOW \ +do \ +{ \ + struct ucontext *_uc = (struct ucontext *)_p; \ + volatile struct sigcontext *_sc = (struct sigcontext *) &_uc->uc_mcontext; \ + \ + register unsigned char *_rip = (unsigned char *)_sc->rip; \ + \ + /* According to the JVM spec, "if the dividend is the negative \ + * integer of largest possible magnitude for the type and the \ + * divisor is -1, then overflow occurs and the result is equal to \ + * the dividend. Despite the overflow, no exception occurs". \ + \ + * We handle this by inspecting the instruction which generated the \ + * signal and advancing ip to point to the following instruction. \ + * As the instructions are variable length it is necessary to do a \ + * little calculation to figure out where the following instruction \ + * actually is. \ + \ + */ \ + \ + bool _is_64_bit = false; \ + \ + if ((_rip[0] & 0xf0) == 0x40) /* REX byte present. */ \ + { \ + unsigned char _rex = _rip[0] & 0x0f; \ + _is_64_bit = (_rex & 0x08) != 0; \ + _rip++; \ + } \ + \ + /* Detect a signed division of Integer.MIN_VALUE or Long.MIN_VALUE. */ \ + if (_rip[0] == 0xf7) \ + { \ + bool _min_value_dividend = false; \ + unsigned char _modrm = _rip[1]; \ + \ + if (((_modrm >> 3) & 7) == 7) \ + { \ + if (_is_64_bit) \ + _min_value_dividend = (_sc->rax == 0x8000000000000000L); \ + else \ + _min_value_dividend = ((_sc->rax & 0xffffffff) == 0x80000000); \ + } \ + \ + if (_min_value_dividend) \ + { \ + unsigned char _rm = _modrm & 7; \ + _sc->rdx = 0; /* the remainder is zero */ \ + switch (_modrm >> 6) \ + { \ + case 0: /* register indirect */ \ + if (_rm == 5) /* 32-bit displacement */ \ + _rip += 4; \ + if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \ + _rip += 1; \ + break; \ + case 1: /* register indirect + 8-bit displacement */ \ + _rip += 1; \ + if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \ + _rip += 1; \ + break; \ + case 2: /* register indirect + 32-bit displacement */ \ + _rip += 4; \ + if (_rm == 4) /* A SIB byte follows the ModR/M byte */ \ + _rip += 1; \ + break; \ + case 3: \ + break; \ + } \ + _rip += 2; \ + _sc->rip = (unsigned long)_rip; \ + return; \ + } \ + } \ +} \ +while (0) extern "C" { @@ -65,12 +144,29 @@ do \ } \ while (0) -/* We use syscall(SYS_rt_sigaction) in INIT_SEGV instead of - * sigaction() because on some systems the pthreads wrappers for - * signal handlers are not compiled with unwind information, so it's - * not possible to unwind through them. This is a problem that will - * go away if all systems ever have pthreads libraries that are - * compiled with unwind info. */ +#define INIT_FPE \ +do \ + { \ + struct kernel_sigaction act; \ + act.k_sa_sigaction = _Jv_catch_fpe; \ + sigemptyset (&act.k_sa_mask); \ + act.k_sa_flags = SA_SIGINFO|0x4000000; \ + act.k_sa_restorer = restore_rt; \ + syscall (SYS_rt_sigaction, SIGFPE, &act, NULL, _NSIG / 8); \ + } \ +while (0) + +/* You might wonder why we use syscall(SYS_sigaction) in INIT_FPE + * instead of the standard sigaction(). This is necessary because of + * the shenanigans above where we increment the PC saved in the + * context and then return. This trick will only work when we are + * called _directly_ by the kernel, because linuxthreads wraps signal + * handlers and its wrappers do not copy the sigcontext struct back + * 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. */ #endif /* JAVA_SIGNAL_H */ -- 2.11.0