signal.c

/*
 * Copyright (C) 2004 PathScale, Inc
 * Licensed under the GPL
 */

#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <sys/mman.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "signal_kern.h"
#include "sysdep/sigcontext.h"
#include "sysdep/signal.h"
#include "sigcontext.h"
#include "time_user.h"
#include "mode.h"

void sig_handler(ARCH_SIGHDLR_PARAM)
{
	struct sigcontext *sc;

	ARCH_GET_SIGCONTEXT(sc, sig);
	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
			 sig, sc);
}

extern int timer_irq_inited;

void alarm_handler(ARCH_SIGHDLR_PARAM)
{
	struct sigcontext *sc;

	ARCH_GET_SIGCONTEXT(sc, sig);
	if(!timer_irq_inited) return;

	if(sig == SIGALRM)
		switch_timers(0);

	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
			 sig, sc);

	if(sig == SIGALRM)
		switch_timers(1);
}

void set_sigstack(void *sig_stack, int size)
{
	stack_t stack = ((stack_t) { .ss_flags	= 0,
				     .ss_sp	= (__ptr_t) sig_stack,
				     .ss_size 	= size - sizeof(void *) });

	if(sigaltstack(&stack, NULL) != 0)
		panic("enabling signal stack failed, errno = %d\n", errno);
}

void remove_sigstack(void)
{
	stack_t stack = ((stack_t) { .ss_flags	= SS_DISABLE,
				     .ss_sp	= NULL,
				     .ss_size	= 0 });

	if(sigaltstack(&stack, NULL) != 0)
		panic("disabling signal stack failed, errno = %d\n", errno);
}

void set_handler(int sig, void (*handler)(int), int flags, ...)
{
	struct sigaction action;
	va_list ap;
	int mask;

	va_start(ap, flags);
	action.sa_handler = handler;
	sigemptyset(&action.sa_mask);
	while((mask = va_arg(ap, int)) != -1){
		sigaddset(&action.sa_mask, mask);
	}
	va_end(ap);
	action.sa_flags = flags;
	action.sa_restorer = NULL;
	if(sigaction(sig, &action, NULL) < 0)
		panic("sigaction failed");
}

int change_sig(int signal, int on)
{
	sigset_t sigset, old;

	sigemptyset(&sigset);
	sigaddset(&sigset, signal);
	sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
	return(!sigismember(&old, signal));
}

/* Both here and in set/get_signal we don't touch SIGPROF, because we must not
 * disable profiling; it's safe because the profiling code does not interact
 * with the kernel code at all.*/

static void change_signals(int type)
{
	sigset_t mask;

	sigemptyset(&mask);
	sigaddset(&mask, SIGVTALRM);
	sigaddset(&mask, SIGALRM);
	sigaddset(&mask, SIGIO);
	if(sigprocmask(type, &mask, NULL) < 0)
		panic("Failed to change signal mask - errno = %d", errno);
}

void block_signals(void)
{
	change_signals(SIG_BLOCK);
}

void unblock_signals(void)
{
	change_signals(SIG_UNBLOCK);
}

/* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
 * together under SIGVTALRM_BIT.  SIGPROF is excluded because we want to
 * be able to profile all of UML, not just the non-critical sections.  If
 * profiling is not thread-safe, then that is not my problem.  We can disable
 * profiling when SMP is enabled in that case.
 */
#define SIGIO_BIT 0
#define SIGVTALRM_BIT 1

static int enable_mask(sigset_t *mask)
{
	int sigs;

	sigs = sigismember(mask, SIGIO) ? 0 : 1 << SIGIO_BIT;
	sigs |= sigismember(mask, SIGVTALRM) ? 0 : 1 << SIGVTALRM_BIT;
	sigs |= sigismember(mask, SIGALRM) ? 0 : 1 << SIGVTALRM_BIT;
	return(sigs);
}

int get_signals(void)
{
	sigset_t mask;

	if(sigprocmask(SIG_SETMASK, NULL, &mask) < 0)
		panic("Failed to get signal mask");
	return(enable_mask(&mask));
}

int set_signals(int enable)
{
	sigset_t mask;
	int ret;

	sigemptyset(&mask);
	if(enable & (1 << SIGIO_BIT))
		sigaddset(&mask, SIGIO);
	if(enable & (1 << SIGVTALRM_BIT)){
		sigaddset(&mask, SIGVTALRM);
		sigaddset(&mask, SIGALRM);
	}

	/* This is safe - sigprocmask is guaranteed to copy locally the
	 * value of new_set, do his work and then, at the end, write to
	 * old_set.
	 */
	if(sigprocmask(SIG_UNBLOCK, &mask, &mask) < 0)
		panic("Failed to enable signals");
	ret = enable_mask(&mask);
	sigemptyset(&mask);
	if((enable & (1 << SIGIO_BIT)) == 0)
		sigaddset(&mask, SIGIO);
	if((enable & (1 << SIGVTALRM_BIT)) == 0){
		sigaddset(&mask, SIGVTALRM);
		sigaddset(&mask, SIGALRM);
	}
	if(sigprocmask(SIG_BLOCK, &mask, NULL) < 0)
		panic("Failed to block signals");

	return(ret);
}