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ocaml/asmrun/signals.c

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/***********************************************************************/
/* */
/* Objective Caml */
/* */
/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
/* */
/* Copyright 1996 Institut National de Recherche en Informatique et */
/* en Automatique. All rights reserved. This file is distributed */
/* under the terms of the GNU Library General Public License, with */
/* the special exception on linking described in file ../LICENSE. */
/* */
/***********************************************************************/
/* $Id$ */
#include <signal.h>
#include <stdio.h>
#if (defined(TARGET_sparc) && defined(SYS_solaris))
#include <ucontext.h>
#endif
#include "alloc.h"
#include "callback.h"
#include "memory.h"
#include "minor_gc.h"
#include "misc.h"
#include "mlvalues.h"
#include "fail.h"
#include "signals.h"
#include "stack.h"
#include "sys.h"
#ifdef HAS_STACK_OVERFLOW_DETECTION
#include <sys/resource.h>
#endif
#ifdef _WIN32
typedef void (*sighandler)(int sig);
extern sighandler win32_signal(int sig, sighandler action);
#define signal(sig,act) win32_signal(sig,act)
#endif
#if defined(TARGET_power) && defined(SYS_rhapsody)
/* Confer machdep/ppc/unix_signal.c and mach/ppc/thread_status.h
in the Darwin sources */
#define CONTEXT_GPR(ctx, regno) \
(((unsigned long *)((ctx)->sc_regs))[2 + (regno)])
#endif
#if defined(TARGET_power) && defined(SYS_aix)
#ifdef _AIXVERSION_430
#define STRUCT_SIGCONTEXT struct __sigcontext
#define CONTEXT_GPR(ctx, regno) \
((ctx)->__sc_jmpbuf.__jmp_context.__gpr[(regno)])
#else
#define STRUCT_SIGCONTEXT struct sigcontext
#define CONTEXT_GPR(ctx, regno) \
((ctx)->sc_jmpbuf.jmp_context.gpr[(regno)])
#endif
#endif
volatile int async_signal_mode = 0;
volatile int pending_signal = 0;
volatile int force_major_slice = 0;
value signal_handlers = 0;
void (*enter_blocking_section_hook)() = NULL;
void (*leave_blocking_section_hook)() = NULL;
static int rev_convert_signal_number(int signo);
/* Execute a signal handler immediately. */
void execute_signal(int signal_number, int in_signal_handler)
{
value res;
#ifdef POSIX_SIGNALS
sigset_t sigs;
/* Block the signal before executing the handler, and record in sigs
the original signal mask */
sigemptyset(&sigs);
sigaddset(&sigs, signal_number);
sigprocmask(SIG_BLOCK, &sigs, &sigs);
#endif
res = callback_exn(Field(signal_handlers, signal_number),
Val_int(rev_convert_signal_number(signal_number)));
#ifdef POSIX_SIGNALS
if (! in_signal_handler) {
/* Restore the original signal mask */
sigprocmask(SIG_SETMASK, &sigs, NULL);
} else if (Is_exception_result(res)) {
/* Restore the original signal mask and unblock the signal itself */
sigdelset(&sigs, signal_number);
sigprocmask(SIG_SETMASK, &sigs, NULL);
}
#endif
if (Is_exception_result(res)) mlraise(Extract_exception(res));
}
/* This routine is the common entry point for garbage collection
and signal handling. It can trigger a callback to Caml code.
With system threads, this callback can cause a context switch.
Hence [garbage_collection] must not be called from regular C code
(e.g. the [alloc] function) because the context of the call
(e.g. [intern_val]) may not allow context switching.
Only generated assembly code can call [garbage_collection],
via the caml_call_gc assembly stubs. */
void garbage_collection(void)
{
int sig;
if (young_ptr < young_start || force_major_slice) minor_collection();
/* If a signal arrives between the following two instructions,
it will be lost. */
sig = pending_signal;
pending_signal = 0;
young_limit = young_start;
if (sig) execute_signal(sig, 0);
}
/* Trigger a garbage collection as soon as possible */
void urge_major_slice (void)
{
force_major_slice = 1;
young_limit = young_end;
/* This is only moderately effective on ports that cache young_limit
in a register, since modify() is called directly, not through
caml_c_call, so it may take a while before the register is reloaded
from young_limit. */
}
void enter_blocking_section(void)
{
int sig;
while (1){
Assert (!async_signal_mode);
/* If a signal arrives between the next two instructions,
it will be lost. */
sig = pending_signal;
pending_signal = 0;
young_limit = young_start;
if (sig) execute_signal(sig, 0);
async_signal_mode = 1;
if (!pending_signal) break;
async_signal_mode = 0;
}
if (enter_blocking_section_hook != NULL) enter_blocking_section_hook();
}
void leave_blocking_section(void)
{
if (leave_blocking_section_hook != NULL) leave_blocking_section_hook();
Assert(async_signal_mode);
async_signal_mode = 0;
}
#if defined(TARGET_alpha) || defined(TARGET_mips)
void handle_signal(int sig, int code, struct sigcontext * context)
#elif defined(TARGET_power) && defined(SYS_aix)
void handle_signal(int sig, int code, STRUCT_SIGCONTEXT * context)
#elif defined(TARGET_power) && defined(SYS_elf)
void handle_signal(int sig, struct sigcontext * context)
#elif defined(TARGET_power) && defined(SYS_rhapsody)
void handle_signal(int sig, int code, struct sigcontext * context)
#else
void handle_signal(int sig)
#endif
{
#if !defined(POSIX_SIGNALS) && !defined(BSD_SIGNALS)
signal(sig, handle_signal);
#endif
if (async_signal_mode) {
/* We are interrupting a C function blocked on I/O.
Callback the Caml code immediately. */
leave_blocking_section();
execute_signal(sig, 1);
enter_blocking_section();
} else {
/* We can't execute the signal code immediately.
Instead, we remember the signal and play with the allocation limit
so that the next allocation will trigger a garbage collection. */
pending_signal = sig;
young_limit = young_end;
/* Some ports cache young_limit in a register.
Use the signal context to modify that register too, but not if
we are inside C code (i.e. caml_last_return_address != 0). */
if (caml_last_return_address == 0) {
#if defined(TARGET_alpha)
/* Cached in register $14 */
context->sc_regs[14] = (long) young_limit;
#endif
#if defined(TARGET_mips)
/* Cached in register $23 */
context->sc_regs[23] = (int) young_limit;
#endif
#if defined(TARGET_power) && defined(SYS_aix)
/* Cached in register 30 */
CONTEXT_GPR(context, 30) = (ulong_t) young_limit;
#endif
#if defined(TARGET_power) && defined(SYS_elf)
/* Cached in register 30 */
context->regs->gpr[30] = (unsigned long) young_limit;
#endif
#if defined(TARGET_power) && defined(SYS_rhapsody)
/* Cached in register 30 */
CONTEXT_GPR(context, 30) = (unsigned long) young_limit;
#endif
}
}
}
#ifndef SIGABRT
#define SIGABRT -1
#endif
#ifndef SIGALRM
#define SIGALRM -1
#endif
#ifndef SIGFPE
#define SIGFPE -1
#endif
#ifndef SIGHUP
#define SIGHUP -1
#endif
#ifndef SIGILL
#define SIGILL -1
#endif
#ifndef SIGINT
#define SIGINT -1
#endif
#ifndef SIGKILL
#define SIGKILL -1
#endif
#ifndef SIGPIPE
#define SIGPIPE -1
#endif
#ifndef SIGQUIT
#define SIGQUIT -1
#endif
#ifndef SIGSEGV
#define SIGSEGV -1
#endif
#ifndef SIGTERM
#define SIGTERM -1
#endif
#ifndef SIGUSR1
#define SIGUSR1 -1
#endif
#ifndef SIGUSR2
#define SIGUSR2 -1
#endif
#ifndef SIGCHLD
#define SIGCHLD -1
#endif
#ifndef SIGCONT
#define SIGCONT -1
#endif
#ifndef SIGSTOP
#define SIGSTOP -1
#endif
#ifndef SIGTSTP
#define SIGTSTP -1
#endif
#ifndef SIGTTIN
#define SIGTTIN -1
#endif
#ifndef SIGTTOU
#define SIGTTOU -1
#endif
#ifndef SIGVTALRM
#define SIGVTALRM -1
#endif
#ifndef SIGPROF
#define SIGPROF -1
#endif
static int posix_signals[] = {
SIGABRT, SIGALRM, SIGFPE, SIGHUP, SIGILL, SIGINT, SIGKILL, SIGPIPE,
SIGQUIT, SIGSEGV, SIGTERM, SIGUSR1, SIGUSR2, SIGCHLD, SIGCONT,
SIGSTOP, SIGTSTP, SIGTTIN, SIGTTOU, SIGVTALRM, SIGPROF
};
int convert_signal_number(int signo)
{
if (signo < 0 && signo >= -(sizeof(posix_signals) / sizeof(int)))
return posix_signals[-signo-1];
else
return signo;
}
static int rev_convert_signal_number(int signo)
{
int i;
for (i = 0; i < sizeof(posix_signals) / sizeof(int); i++)
if (signo == posix_signals[i]) return -i - 1;
return signo;
}
#ifndef NSIG
#define NSIG 64
#endif
value install_signal_handler(value signal_number, value action) /* ML */
{
CAMLparam2 (signal_number, action);
int sig;
void (*act)(int signo), (*oldact)(int signo);
#ifdef POSIX_SIGNALS
struct sigaction sigact, oldsigact;
#endif
CAMLlocal1 (res);
sig = convert_signal_number(Int_val(signal_number));
if (sig < 0 || sig >= NSIG)
invalid_argument("Sys.signal: unavailable signal");
switch(action) {
case Val_int(0): /* Signal_default */
act = SIG_DFL;
break;
case Val_int(1): /* Signal_ignore */
act = SIG_IGN;
break;
default: /* Signal_handle */
act = (void (*)(int)) handle_signal;
break;
}
#ifdef POSIX_SIGNALS
sigact.sa_handler = act;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
if (sigaction(sig, &sigact, &oldsigact) == -1) sys_error(NO_ARG);
oldact = oldsigact.sa_handler;
#else
oldact = signal(sig, act);
if (oldact == SIG_ERR) sys_error(NO_ARG);
#endif
if (oldact == (void (*)(int)) handle_signal) {
res = alloc_small(1, 0); /* Signal_handle */
Field(res, 0) = Field(signal_handlers, sig);
}
else if (oldact == SIG_IGN)
res = Val_int(1); /* Signal_ignore */
else
res = Val_int(0); /* Signal_default */
if (Is_block(action)) {
if (signal_handlers == 0) {
signal_handlers = alloc(NSIG, 0);
register_global_root(&signal_handlers);
}
modify(&Field(signal_handlers, sig), Field(action, 0));
}
CAMLreturn (res);
}
/* Machine- and OS-dependent handling of bound check trap */
#if defined(TARGET_sparc) && defined(SYS_sunos)
static void trap_handler(int sig, int code,
struct sigcontext * context, char * address)
{
int * sp;
/* Unblock SIGILL */
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGILL);
sigprocmask(SIG_UNBLOCK, &mask, NULL);
if (code != ILL_TRAP_FAULT(5)) {
fprintf(stderr, "Fatal error: illegal instruction, code 0x%x\n", code);
exit(100);
}
/* Recover young_ptr and caml_exception_pointer from the %l5 and %l6 regs */
sp = (int *) context->sc_sp;
caml_exception_pointer = (char *) sp[5];
young_ptr = (char *) sp[6];
array_bound_error();
}
#endif
#if defined(TARGET_sparc) && defined(SYS_solaris)
static void trap_handler(int sig, siginfo_t * info, void * arg)
{
ucontext_t * context;
int * sp;
if (info->si_code != ILL_ILLTRP) {
fprintf(stderr, "Fatal error: illegal instruction, code 0x%x\n",
info->si_code);
exit(100);
}
/* Recover young_ptr and caml_exception_pointer from the %l5 and %l6 regs */
context = (ucontext_t *) arg;
sp = (int *) context->uc_mcontext.gregs[REG_SP];
caml_exception_pointer = (char *) sp[5];
young_ptr = (char *) sp[6];
array_bound_error();
}
#endif
#if defined(TARGET_sparc) && (defined(SYS_bsd) || defined(SYS_linux))
static void trap_handler(int sig)
{
/* TODO: recover registers from context and call array_bound_error */
fatal_error("Fatal error: out-of-bound access in array or string\n");
}
#endif
#if defined(TARGET_power) && defined(SYS_aix)
static void trap_handler(int sig, int code, STRUCT_SIGCONTEXT * context)
{
/* Unblock SIGTRAP */
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGTRAP);
sigprocmask(SIG_UNBLOCK, &mask, NULL);
/* Recover young_ptr and caml_exception_pointer from registers 31 and 29 */
caml_exception_pointer = (char *) CONTEXT_GPR(context, 29);
young_ptr = (char *) CONTEXT_GPR(context, 31);
array_bound_error();
}
#endif
#if defined(TARGET_power) && defined(SYS_elf)
static void trap_handler(int sig, struct sigcontext * context)
{
/* Recover young_ptr and caml_exception_pointer from registers 31 and 29 */
caml_exception_pointer = (char *) context->regs->gpr[29];
young_ptr = (char *) context->regs->gpr[31];
array_bound_error();
}
#endif
#if defined(TARGET_power) && defined(SYS_rhapsody)
static void trap_handler(int sig, int code, struct sigcontext * context)
{
/* Unblock SIGTRAP */
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGTRAP);
sigprocmask(SIG_UNBLOCK, &mask, NULL);
/* Recover young_ptr and caml_exception_pointer from registers 31 and 29 */
caml_exception_pointer = (char *) CONTEXT_GPR(context, 29);
young_ptr = (char *) CONTEXT_GPR(context, 31);
array_bound_error();
}
#endif
/* Machine- and OS-dependent handling of stack overflow */
#ifdef HAS_STACK_OVERFLOW_DETECTION
static char * system_stack_top;
static char sig_alt_stack[SIGSTKSZ];
static int is_stack_overflow(char * fault_addr, unsigned long in_c_code)
{
struct rlimit limit;
struct sigaction act;
/* Sanity checks:
- faulting address is word-aligned
- faulting address is within the stack
- we are not inside C code */
if (in_c_code == 0 &&
((long) fault_addr & (sizeof(long) - 1)) == 0 &&
getrlimit(RLIMIT_STACK, &limit) == 0 &&
fault_addr < system_stack_top &&
fault_addr >= system_stack_top - limit.rlim_cur - 0x2000) {
/* OK, caller can turn this into a Stack_overflow exception */
return 1;
} else {
/* Otherwise, deactivate our exception handler. Caller will
return, causing fatal signal to be generated at point of error. */
act.sa_handler = SIG_DFL;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
sigaction(SIGSEGV, &act, NULL);
return 0;
}
}
#if defined(TARGET_i386) && defined(SYS_linux_elf)
static void segv_handler(int signo, struct sigcontext sc)
{
if (is_stack_overflow((char *) sc.cr2, 0))
raise_stack_overflow();
}
#endif
#if defined(TARGET_i386) && !defined(SYS_linux_elf)
static void segv_handler(int signo, siginfo_t * info, void * arg)
{
if (is_stack_overflow((char *) info->si_addr, 0))
raise_stack_overflow();
}
#endif
#endif
/* Initialization of signal stuff */
void init_signals(void)
{
/* Bound-check trap handling */
#if defined(TARGET_sparc) && \
(defined(SYS_sunos) || defined(SYS_bsd) || defined(SYS_linux))
{
struct sigaction act;
act.sa_handler = (void (*)(int)) trap_handler;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGILL, &act, NULL);
}
#endif
#if defined(TARGET_sparc) && defined(SYS_solaris)
{
struct sigaction act;
act.sa_sigaction = trap_handler;
sigemptyset(&act.sa_mask);
act.sa_flags = SA_SIGINFO | SA_NODEFER;
sigaction(SIGILL, &act, NULL);
}
#endif
#if defined(TARGET_power)
{
struct sigaction act;
act.sa_handler = (void (*)(int)) trap_handler;
sigemptyset(&act.sa_mask);
#if defined(SYS_rhapsody) || defined(SYS_aix)
act.sa_flags = 0;
#else
act.sa_flags = SA_NODEFER;
#endif
sigaction(SIGTRAP, &act, NULL);
}
#endif
/* Stack overflow handling */
#ifdef HAS_STACK_OVERFLOW_DETECTION
{
struct sigaltstack stk;
struct sigaction act;
stk.ss_sp = sig_alt_stack;
stk.ss_size = SIGSTKSZ;
stk.ss_flags = 0;
#if defined(TARGET_i386) && defined(SYS_linux_elf)
act.sa_handler = (void (*)(int)) segv_handler;
act.sa_flags = SA_ONSTACK | SA_NODEFER;
#else
act.sa_sigaction = segv_handler;
act.sa_flags = SA_SIGINFO | SA_ONSTACK | SA_NODEFER;
#endif
sigemptyset(&act.sa_mask);
system_stack_top = (char *) &act;
if (sigaltstack(&stk, NULL) == 0) { sigaction(SIGSEGV, &act, NULL); }
}
#endif
}
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