signal.c

linux-2.6.15.6

/*
 * Copyright (C) 2003, Axis Communications AB.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>

#include <asm/io.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/arch/ptrace.h>
#include <asm/arch/hwregs/cpu_vect.h>

extern unsigned long cris_signal_return_page;

/* Flag to check if a signal is blockable. */
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/*
 * A syscall in CRIS is really a "break 13" instruction, which is 2
 * bytes. The registers is manipulated so upon return the instruction
 * will be executed again.
 *
 * This relies on that PC points to the instruction after the break call.
 */
#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;

/* Signal frames. */
struct signal_frame {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS - 1];
	unsigned char retcode[8];	/* Trampoline code. */
};

struct rt_signal_frame {
	struct siginfo *pinfo;
	void *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned char retcode[8];	/* Trampoline code. */
};

int do_signal(int restart, sigset_t *oldset, struct pt_regs *regs);
void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
		      struct pt_regs *regs);
/*
 * Swap in the new signal mask, and wait for a signal. Define some
 * dummy arguments to be able to reach the regs argument.
 */
int
sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
	       long srp, struct pt_regs *regs)
{
	sigset_t saveset;

	mask &= _BLOCKABLE;

	spin_lock_irq(&current->sighand->siglock);

	saveset = current->blocked;

	siginitset(&current->blocked, mask);

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	regs->r10 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();

		if (do_signal(0, &saveset, regs)) {
			/*
			 * This point is reached twice: once to call
			 * the signal handler, then again to return
			 * from the sigsuspend system call. When
			 * calling the signal handler, R10 hold the
			 * signal number as set by do_signal(). The
			 * sigsuspend  call will always return with
			 * the restored value above; -EINTR.
			 */
			return regs->r10;
		}
	}
}

/* Define some dummy arguments to be able to reach the regs argument. */
int
sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r12, long r13,
		  long mof, long srp, struct pt_regs *regs)
{
	sigset_t saveset;
	sigset_t newset;

	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;

	sigdelsetmask(&newset, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);

	saveset = current->blocked;
	current->blocked = newset;

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	regs->r10 = -EINTR;

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();

		if (do_signal(0, &saveset, regs)) {
			/* See comment in function above. */
			return regs->r10;
		}
	}
}

int
sys_sigaction(int signal, const struct old_sigaction *act,
	      struct old_sigaction *oact)
{
	int retval;
	struct k_sigaction newk;
	struct k_sigaction oldk;

	if (act) {
		old_sigset_t mask;

		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(newk.sa.sa_handler, &act->sa_handler) ||
		    __get_user(newk.sa.sa_restorer, &act->sa_restorer))
			return -EFAULT;

		__get_user(newk.sa.sa_flags, &act->sa_flags);
		__get_user(mask, &act->sa_mask);
		siginitset(&newk.sa.sa_mask, mask);
	}

	retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);

	if (!retval && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(oldk.sa.sa_restorer, &oact->sa_restorer))
			return -EFAULT;

		__put_user(oldk.sa.sa_flags, &oact->sa_flags);
		__put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return retval;
}

int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
	return do_sigaltstack(uss, uoss, rdusp());
}

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
	unsigned int err = 0;
	unsigned long old_usp;

        /* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	/*
	 * Restore the registers from &sc->regs. sc is already checked
	 * for VERIFY_READ since the signal_frame was previously
	 * checked in sys_sigreturn().
	 */
	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
		goto badframe;

	/* Make that the user-mode flag is set. */
	regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));

	/* Restore the old USP. */
	err |= __get_user(old_usp, &sc->usp);
	wrusp(old_usp);

	return err;

badframe:
	return 1;
}

/* Define some dummy arguments to be able to reach the regs argument. */
asmlinkage int
sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
	      struct pt_regs *regs)
{
	sigset_t set;
	struct signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct signal_frame *) rdusp();

	/*
	 * Since the signal is stacked on a dword boundary, the frame
	 * should be dword aligned here as well. It it's not, then the
	 * user is trying some funny business.
	 */
	if (((long)frame) & 3)
		goto badframe;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__get_user(set.sig[0], &frame->sc.oldmask) ||
	    (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
						 frame->extramask,
						 sizeof(frame->extramask))))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);

	current->blocked = set;

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->sc))
		goto badframe;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/* Define some dummy variables to be able to reach the regs argument. */
asmlinkage int
sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
		 struct pt_regs *regs)
{
	sigset_t set;
	struct rt_signal_frame __user *frame;
	unsigned long oldspc = regs->spc;
	unsigned long oldccs = regs->ccs;

	frame = (struct rt_signal_frame *) rdusp();

	/*
	 * Since the signal is stacked on a dword boundary, the frame
	 * should be dword aligned here as well. It it's not, then the
	 * user is trying some funny business.
	 */
	if (((long)frame) & 3)
		goto badframe;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);

	current->blocked = set;

	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
		goto badframe;

	if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT)
 		goto badframe;

	keep_debug_flags(oldccs, oldspc, regs);

	return regs->r10;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/* Setup a signal frame. */
static int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
		 unsigned long mask)
{
	int err;
	unsigned long usp;

	err = 0;
	usp = rdusp();

	/*
	 * Copy the registers. They are located first in sc, so it's
	 * possible to use sc directly.
	 */
	err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));

	err |= __put_user(mask, &sc->oldmask);
	err |= __put_user(usp, &sc->usp);

	return err;
}

/* Figure out where to put the new signal frame - usually on the stack. */
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
	unsigned long sp;

	sp = rdusp();

	/* This is the X/Open sanctioned signal stack switching. */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (!on_sig_stack(sp))
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	/* Make sure the frame is dword-aligned. */
	sp &= ~3;

	return (void __user *)(sp - frame_size);
}

/* Grab and setup a signal frame.
 *
 * Basically a lot of state-info is stacked, and arranged for the
 * user-mode program to return to the kernel using either a trampiline
 * which performs the syscall sigreturn(), or a provided user-mode
 * trampoline.
  */
static void