path: root/arch/xtensa/kernel/signal.c

/*
 * arch/xtensa/kernel/signal.c
 *
 * Default platform functions.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2005, 2006 Tensilica Inc.
 * Copyright (C) 1991, 1992  Linus Torvalds
 * 1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 * Chris Zankel <chris@zankel.net>
 * Joe Taylor <joe@tensilica.com>
 */

#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <linux/tracehook.h>
#include <linux/sched/task_stack.h>

#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/coprocessor.h>
#include <asm/unistd.h>

extern struct task_struct *coproc_owners[];

struct rt_sigframe
{
	struct siginfo info;
	struct ucontext uc;
	struct {
		xtregs_opt_t opt;
		xtregs_user_t user;
#if XTENSA_HAVE_COPROCESSORS
		xtregs_coprocessor_t cp;
#endif
	} xtregs;
	unsigned char retcode[6];
	unsigned int window[4];
};

/* 
 * Flush register windows stored in pt_regs to stack.
 * Returns 1 for errors.
 */

int
flush_window_regs_user(struct pt_regs *regs)
{
	const unsigned long ws = regs->windowstart;
	const unsigned long wb = regs->windowbase;
	unsigned long sp = 0;
	unsigned long wm;
	int err = 1;
	int base;

	/* Return if no other frames. */

	if (regs->wmask == 1)
		return 0;

	/* Rotate windowmask and skip empty frames. */

	wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
	base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
		
	/* For call8 or call12 frames, we need the previous stack pointer. */

	if ((regs->wmask & 2) == 0)
		if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
			goto errout;

	/* Spill frames to stack. */

	while (base < XCHAL_NUM_AREGS / 4) {

		int m = (wm >> base);
		int inc = 0;

		/* Save registers a4..a7 (call8) or a4...a11 (call12) */

		if (m & 2) {			/* call4 */
			inc = 1;

		} else if (m & 4) {		/* call8 */
			if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4),
					 &regs->areg[(base + 1) * 4], 16))
				goto errout;
			inc = 2;

		} else if (m & 8) {	/* call12 */
			if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4),
					 &regs->areg[(base + 1) * 4], 32))
				goto errout;
			inc = 3;
		}

		/* Save current frame a0..a3 under next SP */

		sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
		if (copy_to_user(&SPILL_SLOT(sp, 0), &regs->areg[base * 4], 16))
			goto errout;

		/* Get current stack pointer for next loop iteration. */

		sp = regs->areg[base * 4 + 1];
		base += inc;
	}

	regs->wmask = 1;
	regs->windowstart = 1 << wb;

	return 0;

errout:
	return err;
}

/*
 * Note: We don't copy double exception 'regs', we have to finish double exc. 
 * first before we return to signal handler! This dbl.exc.handler might cause 
 * another double exception, but I think we are fine as the situation is the 
 * same as if we had returned to the signal handerl and got an interrupt 
 * immediately...
 */

static int
setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
{
	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
	struct thread_info *ti = current_thread_info();
	int err = 0;

#define COPY(x)	err |= __put_user(regs->x, &sc->sc_##x)
	COPY(pc);
	COPY(ps);
	COPY(lbeg);
	COPY(lend);
	COPY(lcount);
	COPY(sar);
#undef COPY

	err |= flush_window_regs_user(regs);
	err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
	err |= __put_user(0, &sc->sc_xtregs);

	if (err)
		return err;

#if XTENSA_HAVE_COPROCESSORS
	coprocessor_flush_all(ti);
	coprocessor_release_all(ti);
	err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
			      sizeof (frame->xtregs.cp));
#endif
	err |= __copy_to_user(&frame->xtregs.opt, &regs->xtregs_opt,
			      sizeof (xtregs_opt_t));
	err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
			      sizeof (xtregs_user_t));

	err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);

	return err;
}

static int
restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
{
	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
	struct thread_info *ti = current_thread_info();
	unsigned int err = 0;
	unsigned long ps;

#define COPY(x)	err |= __get_user(regs->x, &sc->sc_##x)
	COPY(pc);
	COPY(lbeg);
	COPY(lend);
	COPY(lcount);
	COPY(sar);
#undef COPY

	/* All registers were flushed to stack. Start with a pristine frame. */

	regs->wmask = 1;
	regs->windowbase = 0;
	regs->windowstart = 1;

	regs->syscall = NO_SYSCALL;	/* disable syscall checks */

	/* For PS, restore only PS.CALLINC.
	 * Assume that all other bits are either the same as for the signal
	 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
	 */
	err |= __get_user(ps, &sc->sc_ps);
	regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);

	/* Additional corruption checks */

	if ((regs->lcount > 0)
	    && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
		err = 1;

	err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);

	if (err)
		return err;

	/* The signal handler may have used coprocessors in which
	 * case they are still enabled.  We disable them to force a
	 * reloading of the original task's CP state by the lazy
	 * context-switching mechanisms of CP exception handling.
	 * Also, we essentially discard any coprocessor state that the
	 * signal handler created. */

#if XTENSA_HAVE_COPROCESSORS
	coprocessor_release_all(ti);
	err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
				sizeof (frame->xtregs.cp));
#endif
	err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
				sizeof (xtregs_user_t));
	err |= __copy_from_user(&regs->xtregs_opt, &frame->xtregs.opt,
				sizeof (xtregs_opt_t));

	return err;
}


/*
 * Do a signal return; undo the signal stack.
 */

asmlinkage long xtensa_rt_sigreturn(void)
{
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe __user *frame;
	sigset_t set;
	int ret;

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

	if (regs->depc > 64)
		panic("rt_sigreturn in double exception!\n");

	frame = (struct rt_sigframe __user *) regs->areg[1];

	if (!access_ok(frame, sizeof(*frame)))
		goto