signal.c

/*
 * Common signal handling code for both 32 and 64 bits
 *
 *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
 *    Extracted from signal_32.c and signal_64.c
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file README.legal in the main directory of
 * this archive for more details.
 */

#include <linux/ptrace.h>
#include <linux/signal.h>
#include <asm/unistd.h>

void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
			   int has_handler)
{
	unsigned long ret = regs->gpr[3];
	int restart = 1;

	/* syscall ? */
	if (TRAP(regs) != 0x0C00)
		return;

	/* error signalled ? */
	if (!(regs->ccr & 0x10000000))
		return;

	switch (ret) {
	case ERESTART_RESTARTBLOCK:
	case ERESTARTNOHAND:
		/* ERESTARTNOHAND means that the syscall should only be
		 * restarted if there was no handler for the signal, and since
		 * we only get here if there is a handler, we dont restart.
		 */
		restart = !has_handler;
		break;
	case ERESTARTSYS:
		/* ERESTARTSYS means to restart the syscall if there is no
		 * handler or the handler was registered with SA_RESTART
		 */
		restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
		break;
	case ERESTARTNOINTR:
		/* ERESTARTNOINTR means that the syscall should be
		 * called again after the signal handler returns.
		 */
		break;
	default:
		return;
	}
	if (restart) {
		if (ret == ERESTART_RESTARTBLOCK)
			regs->gpr[0] = __NR_restart_syscall;
		else
			regs->gpr[3] = regs->orig_gpr3;
		regs->nip -= 4;
		regs->result = 0;
	} else {
		regs->result = -EINTR;
		regs->gpr[3] = EINTR;
		regs->ccr |= 0x10000000;
	}
}