arch/um/os-Linux/signal.c - kernel/msm - Gitiles

 /*
  * 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.h"
 #include "signal_kern.h"
 #include "sysdep/sigcontext.h"
 #include "sysdep/barrier.h"
 #include "sigcontext.h"
 #include "mode.h"
 #include "os.h"

 /* 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 SIGIO_MASK (1 << SIGIO_BIT)

 #define SIGVTALRM_BIT 1
 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)

 #define SIGALRM_BIT 2
 #define SIGALRM_MASK (1 << SIGALRM_BIT)

 /* These are used by both the signal handlers and
  * block/unblock_signals.  I don't want modifications cached in a
  * register - they must go straight to memory.
  */
 static volatile int signals_enabled = 1;
 static volatile int pending = 0;

 void sig_handler(int sig, struct sigcontext *sc)
 {
 	int enabled;

 	enabled = signals_enabled;
 	if(!enabled && (sig == SIGIO)){
 		pending |= SIGIO_MASK;
 		return;
 	}

 	block_signals();

 	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
 			 sig, sc);

 	set_signals(enabled);
 }

 static void real_alarm_handler(int sig, struct sigcontext *sc)
 {
 	union uml_pt_regs regs;

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

 	if(sc != NULL)
 		copy_sc(&regs, sc);
 	regs.skas.is_user = 0;
 	unblock_signals();
 	timer_handler(sig, &regs);

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

 void alarm_handler(int sig, struct sigcontext *sc)
 {
 	int enabled;

 	enabled = signals_enabled;
 	if(!signals_enabled){
 		if(sig == SIGVTALRM)
 			pending |= SIGVTALRM_MASK;
 		else pending |= SIGALRM_MASK;

 		return;
 	}

 	block_signals();

 	real_alarm_handler(sig, sc);
 	set_signals(enabled);
 }

 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 (*handlers[_NSIG])(int sig, struct sigcontext *sc);

 void handle_signal(int sig, struct sigcontext *sc)
 {
 	unsigned long pending = 0;

 	do {
 		int nested, bail;

 		/*
 		 * pending comes back with one bit set for each
 		 * interrupt that arrived while setting up the stack,
 		 * plus a bit for this interrupt, plus the zero bit is
 		 * set if this is a nested interrupt.
 		 * If bail is true, then we interrupted another
 		 * handler setting up the stack.  In this case, we
 		 * have to return, and the upper handler will deal
 		 * with this interrupt.
 		 */
 		bail = to_irq_stack(sig, &pending);
 		if(bail)
 			return;

 		nested = pending & 1;
 		pending &= ~1;

 		while((sig = ffs(pending)) != 0){
 			sig--;
 			pending &= ~(1 << sig);
 			(*handlers[sig])(sig, sc);
 		}

 		/* Again, pending comes back with a mask of signals
 		 * that arrived while tearing down the stack.  If this
 		 * is non-zero, we just go back, set up the stack
 		 * again, and handle the new interrupts.
 		 */
 		if(!nested)
 			pending = from_irq_stack(nested);
 	} while(pending);
 }

 extern void hard_handler(int sig);

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

 	handlers[sig] = (void (*)(int, struct sigcontext *)) handler;
 	action.sa_handler = hard_handler;

 	sigemptyset(&action.sa_mask);

 	va_start(ap, flags);
 	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 - errno = %d\n", errno);

 	sigemptyset(&sig_mask);
 	sigaddset(&sig_mask, sig);
 	if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
 		panic("sigprocmask failed - errno = %d\n", errno);
 }

 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));
 }

 void block_signals(void)
 {
 	signals_enabled = 0;
 	/* This must return with signals disabled, so this barrier
 	 * ensures that writes are flushed out before the return.
 	 * This might matter if gcc figures out how to inline this and
 	 * decides to shuffle this code into the caller.
 	 */
 	mb();
 }

 void unblock_signals(void)
 {
 	int save_pending;

 	if(signals_enabled == 1)
 		return;

 	/* We loop because the IRQ handler returns with interrupts off.  So,
 	 * interrupts may have arrived and we need to re-enable them and
 	 * recheck pending.
 	 */
 	while(1){
 		/* Save and reset save_pending after enabling signals.  This
 		 * way, pending won't be changed while we're reading it.
 		 */
 		signals_enabled = 1;

 		/* Setting signals_enabled and reading pending must
 		 * happen in this order.
 		 */
 		mb();

 		save_pending = pending;
 		if(save_pending == 0){
 			/* This must return with signals enabled, so
 			 * this barrier ensures that writes are
 			 * flushed out before the return.  This might
 			 * matter if gcc figures out how to inline
 			 * this (unlikely, given its size) and decides
 			 * to shuffle this code into the caller.
 			 */
 			mb();
 			return;
 		}

 		pending = 0;

 		/* We have pending interrupts, so disable signals, as the
 		 * handlers expect them off when they are called.  They will
 		 * be enabled again above.
 		 */

 		signals_enabled = 0;

 		/* Deal with SIGIO first because the alarm handler might
 		 * schedule, leaving the pending SIGIO stranded until we come
 		 * back here.
 		 */
 		if(save_pending & SIGIO_MASK)
 			CHOOSE_MODE_PROC(sig_handler_common_tt,
 					 sig_handler_common_skas, SIGIO, NULL);

 		if(save_pending & SIGALRM_MASK)
 			real_alarm_handler(SIGALRM, NULL);

 		if(save_pending & SIGVTALRM_MASK)
 			real_alarm_handler(SIGVTALRM, NULL);
 	}
 }

 int get_signals(void)
 {
 	return signals_enabled;
 }

 int set_signals(int enable)
 {
 	int ret;
 	if(signals_enabled == enable)
 		return enable;

 	ret = signals_enabled;
 	if(enable)
 		unblock_signals();
 	else block_signals();

 	return ret;
 }
	/*
	* 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.h"
	#include "signal_kern.h"
	#include "sysdep/sigcontext.h"
	#include "sysdep/barrier.h"
	#include "sigcontext.h"
	#include "mode.h"
	#include "os.h"

	/* 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 SIGIO_MASK (1 << SIGIO_BIT)

	#define SIGVTALRM_BIT 1
	#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)

	#define SIGALRM_BIT 2
	#define SIGALRM_MASK (1 << SIGALRM_BIT)

	/* These are used by both the signal handlers and
	* block/unblock_signals. I don't want modifications cached in a
	* register - they must go straight to memory.
	*/
	static volatile int signals_enabled = 1;
	static volatile int pending = 0;

	void sig_handler(int sig, struct sigcontext *sc)
	{
	int enabled;

	enabled = signals_enabled;
	if(!enabled && (sig == SIGIO)){
	pending \|= SIGIO_MASK;
	return;
	}

	block_signals();

	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
	sig, sc);

	set_signals(enabled);
	}

	static void real_alarm_handler(int sig, struct sigcontext *sc)
	{
	union uml_pt_regs regs;

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

	if(sc != NULL)
	copy_sc(&regs, sc);
	regs.skas.is_user = 0;
	unblock_signals();
	timer_handler(sig, &regs);

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

	void alarm_handler(int sig, struct sigcontext *sc)
	{
	int enabled;

	enabled = signals_enabled;
	if(!signals_enabled){
	if(sig == SIGVTALRM)
	pending \|= SIGVTALRM_MASK;
	else pending \|= SIGALRM_MASK;

	return;
	}

	block_signals();

	real_alarm_handler(sig, sc);
	set_signals(enabled);
	}

	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 (handlers[_NSIG])(int sig, struct sigcontext sc);

	void handle_signal(int sig, struct sigcontext *sc)
	{
	unsigned long pending = 0;

	do {
	int nested, bail;

	/*
	* pending comes back with one bit set for each
	* interrupt that arrived while setting up the stack,
	* plus a bit for this interrupt, plus the zero bit is
	* set if this is a nested interrupt.
	* If bail is true, then we interrupted another
	* handler setting up the stack. In this case, we
	* have to return, and the upper handler will deal
	* with this interrupt.
	*/
	bail = to_irq_stack(sig, &pending);
	if(bail)
	return;

	nested = pending & 1;
	pending &= ~1;

	while((sig = ffs(pending)) != 0){
	sig--;
	pending &= ~(1 << sig);
	(*handlers[sig])(sig, sc);
	}

	/* Again, pending comes back with a mask of signals
	* that arrived while tearing down the stack. If this
	* is non-zero, we just go back, set up the stack
	* again, and handle the new interrupts.
	*/
	if(!nested)
	pending = from_irq_stack(nested);
	} while(pending);
	}

	extern void hard_handler(int sig);

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

	handlers[sig] = (void ()(int, struct sigcontext )) handler;
	action.sa_handler = hard_handler;

	sigemptyset(&action.sa_mask);

	va_start(ap, flags);
	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 - errno = %d\n", errno);

	sigemptyset(&sig_mask);
	sigaddset(&sig_mask, sig);
	if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
	panic("sigprocmask failed - errno = %d\n", errno);
	}

	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));
	}

	void block_signals(void)
	{
	signals_enabled = 0;
	/* This must return with signals disabled, so this barrier
	* ensures that writes are flushed out before the return.
	* This might matter if gcc figures out how to inline this and
	* decides to shuffle this code into the caller.
	*/
	mb();
	}

	void unblock_signals(void)
	{
	int save_pending;

	if(signals_enabled == 1)
	return;

	/* We loop because the IRQ handler returns with interrupts off. So,
	* interrupts may have arrived and we need to re-enable them and
	* recheck pending.
	*/
	while(1){
	/* Save and reset save_pending after enabling signals. This
	* way, pending won't be changed while we're reading it.
	*/
	signals_enabled = 1;

	/* Setting signals_enabled and reading pending must
	* happen in this order.
	*/
	mb();

	save_pending = pending;
	if(save_pending == 0){
	/* This must return with signals enabled, so
	* this barrier ensures that writes are
	* flushed out before the return. This might
	* matter if gcc figures out how to inline
	* this (unlikely, given its size) and decides
	* to shuffle this code into the caller.
	*/
	mb();
	return;
	}

	pending = 0;

	/* We have pending interrupts, so disable signals, as the
	* handlers expect them off when they are called. They will
	* be enabled again above.
	*/

	signals_enabled = 0;

	/* Deal with SIGIO first because the alarm handler might
	* schedule, leaving the pending SIGIO stranded until we come
	* back here.
	*/
	if(save_pending & SIGIO_MASK)
	CHOOSE_MODE_PROC(sig_handler_common_tt,
	sig_handler_common_skas, SIGIO, NULL);

	if(save_pending & SIGALRM_MASK)
	real_alarm_handler(SIGALRM, NULL);

	if(save_pending & SIGVTALRM_MASK)
	real_alarm_handler(SIGVTALRM, NULL);
	}
	}

	int get_signals(void)
	{
	return signals_enabled;
	}

	int set_signals(int enable)
	{
	int ret;
	if(signals_enabled == enable)
	return enable;

	ret = signals_enabled;
	if(enable)
	unblock_signals();
	else block_signals();

	return ret;
	}