[linux-2.6-block.git] / arch / sparc / kernel / signal_32.c

/*  linux/arch/sparc/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
 *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
 */

#include <linux/sched.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/mm.h>
#include <linux/tty.h>
#include <linux/smp.h>
#include <linux/binfmts.h>	/* do_coredum */
#include <linux/bitops.h>
#include <linux/tracehook.h>

#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>	/* flush_sig_insns */
#include <asm/switch_to.h>

#include "sigutil.h"

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
		   void *fpqueue, unsigned long *fpqdepth);
extern void fpload(unsigned long *fpregs, unsigned long *fsr);

struct signal_frame {
	struct sparc_stackf	ss;
	__siginfo32_t		info;
	__siginfo_fpu_t __user	*fpu_save;
	unsigned long		insns[2] __attribute__ ((aligned (8)));
	unsigned int		extramask[_NSIG_WORDS - 1];
	unsigned int		extra_size; /* Should be 0 */
	__siginfo_rwin_t __user	*rwin_save;
} __attribute__((aligned(8)));

struct rt_signal_frame {
	struct sparc_stackf	ss;
	siginfo_t		info;
	struct pt_regs		regs;
	sigset_t		mask;
	__siginfo_fpu_t __user	*fpu_save;
	unsigned int		insns[2];
	stack_t			stack;
	unsigned int		extra_size; /* Should be 0 */
	__siginfo_rwin_t __user	*rwin_save;
} __attribute__((aligned(8)));

/* Align macros */
#define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
#define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))

static int _sigpause_common(old_sigset_t set)
{
	sigset_t blocked;
	siginitset(&blocked, set);
	return sigsuspend(&blocked);
}

asmlinkage int sys_sigsuspend(old_sigset_t set)
{
	return _sigpause_common(set);
}

asmlinkage void do_sigreturn(struct pt_regs *regs)
{
	struct signal_frame __user *sf;
	unsigned long up_psr, pc, npc;
	sigset_t set;
	__siginfo_fpu_t __user *fpu_save;
	__siginfo_rwin_t __user *rwin_save;
	int err;

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

	synchronize_user_stack();

	sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];

	/* 1. Make sure we are not getting garbage from the user */
	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
		goto segv_and_exit;

	if (((unsigned long) sf) & 3)
		goto segv_and_exit;

	err = __get_user(pc,  &sf->info.si_regs.pc);
	err |= __get_user(npc, &sf->info.si_regs.npc);

	if ((pc | npc) & 3)
		goto segv_and_exit;

	/* 2. Restore the state */
	up_psr = regs->psr;
	err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));

	/* User can only change condition codes and FPU enabling in %psr. */
	regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
		  | (regs->psr & (PSR_ICC | PSR_EF));

	/* Prevent syscall restart.  */
	pt_regs_clear_syscall(regs);

	err |= __get_user(fpu_save, &sf->fpu_save);
	if (fpu_save)
		err |= restore_fpu_state(regs, fpu_save);
	err |= __get_user(rwin_save, &sf->rwin_save);
	if (rwin_save)
		err |= restore_rwin_state(rwin_save);

	/* This is pretty much atomic, no amount locking would prevent
	 * the races which exist anyways.
	 */
	err |= __get_user(set.sig[0], &sf->info.si_mask);
	err |= __copy_from_user(&set.sig[1], &sf->extramask,
			        (_NSIG_WORDS-1) * sizeof(unsigned int));
			   
	if (err)
		goto segv_and_exit;

	sigdelsetmask(&set, ~_BLOCKABLE);
	set_current_blocked(&set);
	return;

segv_and_exit:
	force_sig(SIGSEGV, current);
}

asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
{
	struct rt_signal_frame __user *sf;
	unsigned int psr, pc, npc;
	__siginfo_fpu_t __user *fpu_save;
	__siginfo_rwin_t __user *rwin_save;
	mm_segment_t old_fs;
	sigset_t set;
	stack_t st;
	int err;

	synchronize_user_stack();
	sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
	    (((unsigned long) sf) & 0x03))
		goto segv;

	err = __get_user(pc, &sf->regs.pc);
	err |= __get_user(npc, &sf->regs.npc);
	err |= ((pc | npc) & 0x03);

	err |= __get_user(regs->y, &sf->regs.y);
	err |= __get_user(psr, &sf->regs.psr);

	err |= __copy_from_user(&regs->u_regs[UREG_G1],
				&sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));

	regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);

	/* Prevent syscall restart.  */
	pt_regs_clear_syscall(regs);

	err |= __get_user(fpu_save, &sf->fpu_save);
	if (!err && fpu_save)
		err |= restore_fpu_state(regs, fpu_save);
	err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
	
	err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
	
	if (err)
		goto segv;
		
	regs->pc = pc;
	regs->npc = npc;
	
	/* It is more difficult to avoid calling this function than to
	 * call it and ignore errors.
	 */
	old_fs = get_fs();
	set_fs(KERNEL_DS);
	do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
	set_fs(old_fs);

	err |= __get_user(rwin_save, &sf->rwin_save);
	if (!err && rwin_save) {
		if (restore_rwin_state(rwin_save))
			goto segv;
	}

	sigdelsetmask(&set, ~_BLOCKABLE);
	set_current_blocked(&set);
	return;
segv:
	force_sig(SIGSEGV, current);
}

/* Checks if the fp is valid */
static inline int invalid_frame_pointer(void __user *fp, int fplen)
{
	if ((((unsigned long) fp) & 7) || !__access_ok((unsigned long)fp, fplen))
		return 1;

	return 0;
}

static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
{
	unsigned long sp = regs->u_regs[UREG_FP];

	/*
	 * If we are on the alternate signal stack and would overflow it, don't.
	 * Return an always-bogus address instead so we will die with SIGSEGV.
	 */
	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
		return (void __user *) -1L;

	/* This is the X/Open sanctioned signal stack switching.  */
	if (sa->sa_flags & SA_ONSTACK) {
		if (sas_ss_flags(sp) == 0)
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	sp -= framesize;

	/* Always align the stack frame.  This handles two cases.  First,
	 * sigaltstack need not be mindful of platform specific stack
	 * alignment.  Second, if we took this signal because the stack
	 * is not aligned properly, we'd like to take the signal cleanly
	 * and report that.
	 */
	sp &= ~15UL;

	return (void __user *) sp;
}

static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
		       int signo, sigset_t *oldset)
{
	struct signal_frame __user *sf;
	int sigframe_size, err, wsaved;
	void __user *tail;

	/* 1. Make sure everything is clean */
	synchronize_user_stack();

	wsaved = current_thread_info()->w_saved;

	sigframe_size = sizeof(*sf);
	if (used_math())
		sigframe_size += sizeof(__siginfo_fpu_t);
	if (wsaved)
		sigframe_size += sizeof(__siginfo_rwin_t);

	sf = (struct signal_frame __user *)
		get_sigframe(&ka->sa, regs, sigframe_size);

	if (invalid_frame_pointer(sf, sigframe_size))
		goto sigill_and_return;

	tail = sf + 1;

	/* 2. Save the current process state */
	err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
	
	err |= __put_user(0, &sf->extra_size);

	if (used_math()) {
		__siginfo_fpu_t __user *fp = tail;
		tail += sizeof(*fp);
		err |= save_fpu_state(regs, fp);
		err |= __put_user(fp, &sf->fpu_save);
	} else {
		err |= __put_user(0, &sf->fpu_save);
	}
	if (wsaved) {
		__siginfo_rwin_t __user *rwp = tail;
		tail += sizeof(*rwp);
		err |= save_rwin_state(wsaved, rwp);
		err |= __put_user(rwp, &sf->rwin_save);
	} else {
		err |= __put_user(0, &sf->rwin_save);
	}

	err |= __put_user(oldset->sig[0], &sf->info.si_mask);
	err |= __copy_to_user(sf->extramask, &oldset->sig[1],
			      (_NSIG_WORDS - 1) * sizeof(unsigned int));
	if (!wsaved) {
		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
				      sizeof(struct reg_window32));
	} else {
		struct reg_window32 *rp;

		rp = &current_thread_info()->reg_window[wsaved - 1];
		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
	}
	if (err)
		goto sigsegv;
	
	/* 3. signal handler back-trampoline and parameters */
	regs->u_regs[UREG_FP] = (unsigned long) sf;
	regs->u_regs[UREG_I0] = signo;
	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
	regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

	/* 4. signal handler */
	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->npc = (regs->pc + 4);

	/* 5. return to kernel instructions */
	if (ka->ka_restorer)
		regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
	else {
		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

		/* mov __NR_sigreturn, %g1 */
		err |= __put_user(0x821020d8, &sf->insns[0]);

		/* t 0x10 */
		err |= __put_user(0x91d02010, &sf->insns[1]);
		if (err)
			goto sigsegv;

		/* Flush instruction space. */
		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
	}
	return 0;

sigill_and_return:
	do_exit(SIGILL);
	return -EINVAL;

sigsegv:
	force_sigsegv(signo, current);
	return -EFAULT;
}

static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
			  int signo, sigset_t *oldset, siginfo_t *info)
{
	struct rt_signal_frame __user *sf;
	int sigframe_size, wsaved;
	void __user *tail;
	unsigned int psr;
	int err;

	synchronize_user_stack();
	wsaved = current_thread_info()->w_saved;
	sigframe_size = sizeof(*sf);
	if (used_math())
		sigframe_size += sizeof(__siginfo_fpu_t);
	if (wsaved)
		sigframe_size += sizeof(__siginfo_rwin_t);
	sf = (struct rt_signal_frame __user *)
		get_sigframe(&ka->sa, regs, sigframe_size);
	if (invalid_frame_pointer(sf, sigframe_size))
		goto sigill;

	tail = sf + 1;
	err  = __put_user(regs->pc, &sf->regs.pc);
	err |= __put_user(regs->npc, &sf->regs.npc);
	err |= __put_user(regs->y, &sf->regs.y);
	psr = regs->psr;
	if (used_math())
		psr |= PSR_EF;
	err |= __put_user(psr, &sf->regs.psr);
	err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
	err |= __put_user(0, &sf->extra_size);

	if (psr & PSR_EF) {
		__siginfo_fpu_t *fp = tail;
		tail += sizeof(*fp);
		err |= save_fpu_state(regs, fp);
		err |= __put_user(fp, &sf->fpu_save);
	} else {
		err |= __put_user(0, &sf->fpu_save);
	}
	if (wsaved) {
		__siginfo_rwin_t *rwp = tail;
		tail += sizeof(*rwp);
		err |= save_rwin_state(wsaved, rwp);
		err |= __put_user(rwp, &sf->rwin_save);
	} else {
		err |= __put_user(0, &sf->rwin_save);
	}
	err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
	
	/* Setup sigaltstack */
	err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
	
	if (!wsaved) {
		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
				      sizeof(struct reg_window32));
	} else {
		struct reg_window32 *rp;

		rp = &current_thread_info()->reg_window[wsaved - 1];
		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
	}

	err |= copy_siginfo_to_user(&sf->info, info);

	if (err)
		goto sigsegv;

	regs->u_regs[UREG_FP] = (unsigned long) sf;
	regs->u_regs[UREG_I0] = signo;
	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
	regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;

	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->npc = (regs->pc + 4);

	if (ka->ka_restorer)
		regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
	else {
		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

		/* mov __NR_sigreturn, %g1 */
		err |= __put_user(0x821020d8, &sf->insns[0]);

		/* t 0x10 */
		err |= __put_user(0x91d02010, &sf->insns[1]);
		if (err)
			goto sigsegv;

		/* Flush instruction space. */
		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
	}
	return 0;

sigill:
	do_exit(SIGILL);
	return -EINVAL;

sigsegv:
	force_sigsegv(signo, current);
	return -EFAULT;
}

static inline int
handle_signal(unsigned long signr, struct k_sigaction *ka,
	      siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
	int err;

	if (ka->sa.sa_flags & SA_SIGINFO)
		err = setup_rt_frame(ka, regs, signr, oldset, info);
	else
		err = setup_frame(ka, regs, signr, oldset);

	if (err)
		return err;

	block_sigmask(ka, signr);
	tracehook_signal_handler(signr, info, ka, regs, 0);

	return 0;
}

static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
				   struct sigaction *sa)
{
	switch(regs->u_regs[UREG_I0]) {
	case ERESTART_RESTARTBLOCK:
	case ERESTARTNOHAND:
	no_system_call_restart:
		regs->u_regs[UREG_I0] = EINTR;
		regs->psr |= PSR_C;
		break;
	case ERESTARTSYS:
		if (!(sa->sa_flags & SA_RESTART))
			goto no_system_call_restart;
		/* fallthrough */
	case ERESTARTNOINTR:
		regs->u_regs[UREG_I0] = orig_i0;
		regs->pc -= 4;
		regs->npc -= 4;
	}
}

/* Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
{
	struct k_sigaction ka;
	int restart_syscall;
	sigset_t *oldset;
	siginfo_t info;
	int signr;

	/* It's a lot of work and synchronization to add a new ptrace
	 * register for GDB to save and restore in order to get
	 * orig_i0 correct for syscall restarts when debugging.
	 *
	 * Although it should be the case that most of the global
	 * registers are volatile across a system call, glibc already
	 * depends upon that fact that we preserve them.  So we can't
	 * just use any global register to save away the orig_i0 value.
	 *
	 * In particular %g2, %g3, %g4, and %g5 are all assumed to be
	 * preserved across a system call trap by various pieces of
	 * code in glibc.
	 *
	 * %g7 is used as the "thread register".   %g6 is not used in
	 * any fixed manner.  %g6 is used as a scratch register and
	 * a compiler temporary, but it's value is never used across
	 * a system call.  Therefore %g6 is usable for orig_i0 storage.
	 */
	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
		regs->u_regs[UREG_G6] = orig_i0;

	if (test_thread_flag(TIF_RESTORE_SIGMASK))
		oldset = &current->saved_sigmask;
	else
		oldset = &current->blocked;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	/* If the debugger messes with the program counter, it clears
	 * the software "in syscall" bit, directing us to not perform
	 * a syscall restart.
	 */
	restart_syscall = 0;
	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
		restart_syscall = 1;
		orig_i0 = regs->u_regs[UREG_G6];
	}


	if (signr > 0) {
		if (restart_syscall)
			syscall_restart(orig_i0, regs, &ka.sa);
		if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
			/* a signal was successfully delivered; the saved
			 * sigmask will have been stored in the signal frame,
			 * and will be restored by sigreturn, so we can simply
			 * clear the TIF_RESTORE_SIGMASK flag.
			 */
			if (test_thread_flag(TIF_RESTORE_SIGMASK))
				clear_thread_flag(TIF_RESTORE_SIGMASK);
		}
		return;
	}
	if (restart_syscall &&
	    (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
	     regs->u_regs[UREG_I0] == ERESTARTSYS ||
	     regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
		/* replay the system call when we are done */
		regs->u_regs[UREG_I0] = orig_i0;
		regs->pc -= 4;
		regs->npc -= 4;
		pt_regs_clear_syscall(regs);
	}
	if (restart_syscall &&
	    regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
		regs->u_regs[UREG_G1] = __NR_restart_syscall;
		regs->pc -= 4;
		regs->npc -= 4;
		pt_regs_clear_syscall(regs);
	}

	/* if there's no signal to deliver, we just put the saved sigmask
	 * back
	 */
	restore_saved_sigmask();
}

void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
		      unsigned long thread_info_flags)
{
	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
		do_signal(regs, orig_i0);
	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
	}
}

asmlinkage int
do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
		unsigned long sp)
{
	int ret = -EFAULT;

	/* First see if old state is wanted. */
	if (ossptr) {
		if (put_user(current->sas_ss_sp + current->sas_ss_size,
			     &ossptr->the_stack) ||
		    __put_user(on_sig_stack(sp), &ossptr->cur_status))
			goto out;
	}

	/* Now see if we want to update the new state. */
	if (ssptr) {
		char *ss_sp;

		if (get_user(ss_sp, &ssptr->the_stack))
			goto out;
		/* If the current stack was set with sigaltstack, don't
		   swap stacks while we are on it.  */
		ret = -EPERM;
		if (current->sas_ss_sp && on_sig_stack(sp))
			goto out;

		/* Since we don't know the extent of the stack, and we don't
		   track onstack-ness, but rather calculate it, we must
		   presume a size.  Ho hum this interface is lossy.  */
		current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
		current->sas_ss_size = SIGSTKSZ;
	}
	ret = 0;
out:
	return ret;
}
Commit	Line	Data
5526b7e4	1	/* linux/arch/sparc/kernel/signal.c
1da177e4 LT	2	*
	3	* Copyright (C) 1991, 1992 Linus Torvalds
	4	* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
	5	* Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
	6	* Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
	7	*/
	8
1da177e4 LT	9	#include <linux/sched.h>
	10	#include <linux/kernel.h>
	11	#include <linux/signal.h>
	12	#include <linux/errno.h>
	13	#include <linux/wait.h>
	14	#include <linux/ptrace.h>
	15	#include <linux/unistd.h>
	16	#include <linux/mm.h>
	17	#include <linux/tty.h>
	18	#include <linux/smp.h>
1da177e4 LT	19	#include <linux/binfmts.h> /* do_coredum */
1da177e4 LT	20	#include <linux/bitops.h>
5a157d5b	21	#include <linux/tracehook.h>
1da177e4 LT	22
	23	#include <asm/uaccess.h>
	24	#include <asm/ptrace.h>
1da177e4 LT	25	#include <asm/pgalloc.h>
	26	#include <asm/pgtable.h>
	27	#include <asm/cacheflush.h> /* flush_sig_insns */
d550bbd4	28	#include <asm/switch_to.h>
1da177e4	29
5598473a DM	30	#include "sigutil.h"
5598473a DM	31
1da177e4 LT	32	#define _BLOCKABLE (~(sigmask(SIGKILL) \| sigmask(SIGSTOP)))
	33
	34	extern void fpsave(unsigned long fpregs, unsigned long fsr,
	35	void fpqueue, unsigned long fpqdepth);
	36	extern void fpload(unsigned long fpregs, unsigned long fsr);
	37
5526b7e4	38	struct signal_frame {
1da177e4	39	struct sparc_stackf ss;
4d7b92ad	40	__siginfo32_t info;
1da177e4 LT	41	__siginfo_fpu_t __user *fpu_save;
	42	unsigned long insns[2] __attribute__ ((aligned (8)));
	43	unsigned int extramask[_NSIG_WORDS - 1];
	44	unsigned int extra_size; /* Should be 0 */
5598473a DM	45	__siginfo_rwin_t __user *rwin_save;
5598473a DM	46	} __attribute__((aligned(8)));
1da177e4 LT	47
	48	struct rt_signal_frame {
	49	struct sparc_stackf ss;
	50	siginfo_t info;
	51	struct pt_regs regs;
	52	sigset_t mask;
	53	__siginfo_fpu_t __user *fpu_save;
	54	unsigned int insns[2];
	55	stack_t stack;
	56	unsigned int extra_size; /* Should be 0 */
5598473a DM	57	__siginfo_rwin_t __user *rwin_save;
5598473a DM	58	} __attribute__((aligned(8)));
1da177e4 LT	59
1da177e4 LT	60	/* Align macros */
5526b7e4	61	#define SF_ALIGNEDSZ (((sizeof(struct signal_frame) + 7) & (~7)))
1da177e4 LT	62	#define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame) + 7) & (~7)))
1da177e4 LT	63
2d7d5f05	64	static int _sigpause_common(old_sigset_t set)
1da177e4	65	{
faddf598	66	sigset_t blocked;
faddf598	67	siginitset(&blocked, set);
68f3f16d	68	return sigsuspend(&blocked);
1da177e4 LT	69	}
1da177e4 LT	70
2d7d5f05	71	asmlinkage int sys_sigsuspend(old_sigset_t set)
1da177e4	72	{
2d7d5f05	73	return _sigpause_common(set);
1da177e4 LT	74	}
1da177e4 LT	75
5526b7e4	76	asmlinkage void do_sigreturn(struct pt_regs *regs)
1da177e4	77	{
5526b7e4	78	struct signal_frame __user *sf;
1da177e4 LT	79	unsigned long up_psr, pc, npc;
	80	sigset_t set;
	81	__siginfo_fpu_t __user *fpu_save;
5598473a	82	__siginfo_rwin_t __user *rwin_save;
1da177e4 LT	83	int err;
1da177e4 LT	84
5526b7e4 DM	85	/* Always make any pending restarted system calls return -EINTR */
	86	current_thread_info()->restart_block.fn = do_no_restart_syscall;
	87
	88	synchronize_user_stack();
	89
	90	sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
1da177e4 LT	91
	92	/* 1. Make sure we are not getting garbage from the user */
	93	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
	94	goto segv_and_exit;
	95
	96	if (((unsigned long) sf) & 3)
	97	goto segv_and_exit;
	98
	99	err = __get_user(pc, &sf->info.si_regs.pc);
	100	err \|= __get_user(npc, &sf->info.si_regs.npc);
	101
	102	if ((pc \| npc) & 3)
	103	goto segv_and_exit;
	104
	105	/* 2. Restore the state */
	106	up_psr = regs->psr;
	107	err \|= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
	108
	109	/* User can only change condition codes and FPU enabling in %psr. */
	110	regs->psr = (up_psr & ~(PSR_ICC \| PSR_EF))
	111	\| (regs->psr & (PSR_ICC \| PSR_EF));
	112
28e61036 DM	113	/* Prevent syscall restart. */
	114	pt_regs_clear_syscall(regs);
	115
1da177e4	116	err \|= __get_user(fpu_save, &sf->fpu_save);
1da177e4 LT	117	if (fpu_save)
1da177e4 LT	118	err \|= restore_fpu_state(regs, fpu_save);
5598473a DM	119	err \|= __get_user(rwin_save, &sf->rwin_save);
	120	if (rwin_save)
	121	err \|= restore_rwin_state(rwin_save);
1da177e4 LT	122
	123	/* This is pretty much atomic, no amount locking would prevent
	124	* the races which exist anyways.
	125	*/
	126	err \|= __get_user(set.sig[0], &sf->info.si_mask);
	127	err \|= __copy_from_user(&set.sig[1], &sf->extramask,
	128	(_NSIG_WORDS-1) * sizeof(unsigned int));
	129
	130	if (err)
	131	goto segv_and_exit;
	132
	133	sigdelsetmask(&set, ~_BLOCKABLE);
faddf598	134	set_current_blocked(&set);
1da177e4 LT	135	return;
	136
	137	segv_and_exit:
	138	force_sig(SIGSEGV, current);
	139	}
	140
1da177e4 LT	141	asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
	142	{
	143	struct rt_signal_frame __user *sf;
	144	unsigned int psr, pc, npc;
	145	__siginfo_fpu_t __user *fpu_save;
5598473a	146	__siginfo_rwin_t __user *rwin_save;
1da177e4 LT	147	mm_segment_t old_fs;
	148	sigset_t set;
	149	stack_t st;
	150	int err;
	151
	152	synchronize_user_stack();
	153	sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
	154	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) \|\|
	155	(((unsigned long) sf) & 0x03))
	156	goto segv;
	157
	158	err = __get_user(pc, &sf->regs.pc);
	159	err \|= __get_user(npc, &sf->regs.npc);
	160	err \|= ((pc \| npc) & 0x03);
	161
	162	err \|= __get_user(regs->y, &sf->regs.y);
	163	err \|= __get_user(psr, &sf->regs.psr);
	164
	165	err \|= __copy_from_user(&regs->u_regs[UREG_G1],
	166	&sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
	167
	168	regs->psr = (regs->psr & ~PSR_ICC) \| (psr & PSR_ICC);
	169
28e61036 DM	170	/* Prevent syscall restart. */
	171	pt_regs_clear_syscall(regs);
	172
1da177e4	173	err \|= __get_user(fpu_save, &sf->fpu_save);
5598473a	174	if (!err && fpu_save)
1da177e4 LT	175	err \|= restore_fpu_state(regs, fpu_save);
	176	err \|= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
	177
	178	err \|= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
	179
	180	if (err)
	181	goto segv;
	182
	183	regs->pc = pc;
	184	regs->npc = npc;
	185
	186	/* It is more difficult to avoid calling this function than to
	187	* call it and ignore errors.
	188	*/
	189	old_fs = get_fs();
	190	set_fs(KERNEL_DS);
	191	do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
	192	set_fs(old_fs);
	193
5598473a DM	194	err \|= __get_user(rwin_save, &sf->rwin_save);
	195	if (!err && rwin_save) {
	196	if (restore_rwin_state(rwin_save))
	197	goto segv;
	198	}
	199
1da177e4	200	sigdelsetmask(&set, ~_BLOCKABLE);
faddf598	201	set_current_blocked(&set);
1da177e4 LT	202	return;
	203	segv:
	204	force_sig(SIGSEGV, current);
	205	}
	206
	207	/* Checks if the fp is valid */
	208	static inline int invalid_frame_pointer(void __user *fp, int fplen)
	209	{
3c23a766	210	if ((((unsigned long) fp) & 7) \|\| !__access_ok((unsigned long)fp, fplen))
1da177e4	211	return 1;
3c23a766	212
1da177e4 LT	213	return 0;
	214	}
	215
	216	static inline void __user get_sigframe(struct sigaction sa, struct pt_regs *regs, unsigned long framesize)
	217	{
dc5dc7e6	218	unsigned long sp = regs->u_regs[UREG_FP];
1da177e4	219
dc5dc7e6 DM	220	/*
	221	* If we are on the alternate signal stack and would overflow it, don't.
	222	* Return an always-bogus address instead so we will die with SIGSEGV.
	223	*/
	224	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
	225	return (void __user *) -1L;
1da177e4 LT	226
	227	/* This is the X/Open sanctioned signal stack switching. */
	228	if (sa->sa_flags & SA_ONSTACK) {
dc5dc7e6	229	if (sas_ss_flags(sp) == 0)
1da177e4 LT	230	sp = current->sas_ss_sp + current->sas_ss_size;
1da177e4 LT	231	}
dc5dc7e6	232
f036d9f3 DM	233	sp -= framesize;
f036d9f3 DM	234
dc5dc7e6 DM	235	/* Always align the stack frame. This handles two cases. First,
	236	* sigaltstack need not be mindful of platform specific stack
	237	* alignment. Second, if we took this signal because the stack
	238	* is not aligned properly, we'd like to take the signal cleanly
	239	* and report that.
	240	*/
f036d9f3	241	sp &= ~15UL;
dc5dc7e6	242
f036d9f3	243	return (void __user *) sp;
1da177e4 LT	244	}
1da177e4 LT	245
392c2180 DM	246	static int setup_frame(struct k_sigaction ka, struct pt_regs regs,
392c2180 DM	247	int signo, sigset_t *oldset)
1da177e4	248	{
5526b7e4	249	struct signal_frame __user *sf;
5598473a DM	250	int sigframe_size, err, wsaved;
5598473a DM	251	void __user *tail;
1da177e4 LT	252
	253	/* 1. Make sure everything is clean */
	254	synchronize_user_stack();
	255
5598473a DM	256	wsaved = current_thread_info()->w_saved;
	257
	258	sigframe_size = sizeof(*sf);
	259	if (used_math())
	260	sigframe_size += sizeof(__siginfo_fpu_t);
	261	if (wsaved)
	262	sigframe_size += sizeof(__siginfo_rwin_t);
1da177e4	263
5526b7e4	264	sf = (struct signal_frame __user *)
1da177e4 LT	265	get_sigframe(&ka->sa, regs, sigframe_size);
	266
	267	if (invalid_frame_pointer(sf, sigframe_size))
	268	goto sigill_and_return;
	269
5598473a	270	tail = sf + 1;
1da177e4 LT	271
	272	/* 2. Save the current process state */
	273	err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
	274
	275	err \|= __put_user(0, &sf->extra_size);
	276
	277	if (used_math()) {
5598473a DM	278	__siginfo_fpu_t __user *fp = tail;
	279	tail += sizeof(*fp);
	280	err \|= save_fpu_state(regs, fp);
	281	err \|= __put_user(fp, &sf->fpu_save);
1da177e4 LT	282	} else {
	283	err \|= __put_user(0, &sf->fpu_save);
	284	}
5598473a DM	285	if (wsaved) {
	286	__siginfo_rwin_t __user *rwp = tail;
	287	tail += sizeof(*rwp);
	288	err \|= save_rwin_state(wsaved, rwp);
	289	err \|= __put_user(rwp, &sf->rwin_save);
	290	} else {
	291	err \|= __put_user(0, &sf->rwin_save);
	292	}
1da177e4 LT	293
	294	err \|= __put_user(oldset->sig[0], &sf->info.si_mask);
	295	err \|= __copy_to_user(sf->extramask, &oldset->sig[1],
	296	(_NSIG_WORDS - 1) * sizeof(unsigned int));
5598473a DM	297	if (!wsaved) {
	298	err \|= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
	299	sizeof(struct reg_window32));
	300	} else {
	301	struct reg_window32 *rp;
	302
	303	rp = &current_thread_info()->reg_window[wsaved - 1];
	304	err \|= __copy_to_user(sf, rp, sizeof(struct reg_window32));
	305	}
1da177e4 LT	306	if (err)
	307	goto sigsegv;
	308
	309	/* 3. signal handler back-trampoline and parameters */
	310	regs->u_regs[UREG_FP] = (unsigned long) sf;
	311	regs->u_regs[UREG_I0] = signo;
	312	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
	313	regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
	314
	315	/* 4. signal handler */
	316	regs->pc = (unsigned long) ka->sa.sa_handler;
	317	regs->npc = (regs->pc + 4);
	318
	319	/* 5. return to kernel instructions */
	320	if (ka->ka_restorer)
	321	regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
	322	else {
	323	regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
	324
	325	/* mov __NR_sigreturn, %g1 */
	326	err \|= __put_user(0x821020d8, &sf->insns[0]);
	327
	328	/* t 0x10 */
	329	err \|= __put_user(0x91d02010, &sf->insns[1]);
	330	if (err)
	331	goto sigsegv;
	332
	333	/* Flush instruction space. */
	334	flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
	335	}
392c2180	336	return 0;
1da177e4 LT	337
	338	sigill_and_return:
	339	do_exit(SIGILL);
392c2180 DM	340	return -EINVAL;
392c2180 DM	341
1da177e4 LT	342	sigsegv:
1da177e4 LT	343	force_sigsegv(signo, current);
392c2180	344	return -EFAULT;
1da177e4 LT	345	}
1da177e4 LT	346
392c2180 DM	347	static int setup_rt_frame(struct k_sigaction ka, struct pt_regs regs,
392c2180 DM	348	int signo, sigset_t oldset, siginfo_t info)
1da177e4 LT	349	{
1da177e4 LT	350	struct rt_signal_frame __user *sf;
5598473a DM	351	int sigframe_size, wsaved;
5598473a DM	352	void __user *tail;
1da177e4 LT	353	unsigned int psr;
	354	int err;
	355
	356	synchronize_user_stack();
5598473a DM	357	wsaved = current_thread_info()->w_saved;
	358	sigframe_size = sizeof(*sf);
	359	if (used_math())
	360	sigframe_size += sizeof(__siginfo_fpu_t);
	361	if (wsaved)
	362	sigframe_size += sizeof(__siginfo_rwin_t);
1da177e4 LT	363	sf = (struct rt_signal_frame __user *)
	364	get_sigframe(&ka->sa, regs, sigframe_size);
	365	if (invalid_frame_pointer(sf, sigframe_size))
	366	goto sigill;
1da177e4	367
5598473a	368	tail = sf + 1;
1da177e4 LT	369	err = __put_user(regs->pc, &sf->regs.pc);
	370	err \|= __put_user(regs->npc, &sf->regs.npc);
	371	err \|= __put_user(regs->y, &sf->regs.y);
	372	psr = regs->psr;
	373	if (used_math())
	374	psr \|= PSR_EF;
	375	err \|= __put_user(psr, &sf->regs.psr);
	376	err \|= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
	377	err \|= __put_user(0, &sf->extra_size);
	378
	379	if (psr & PSR_EF) {
5598473a DM	380	__siginfo_fpu_t *fp = tail;
	381	tail += sizeof(*fp);
	382	err \|= save_fpu_state(regs, fp);
	383	err \|= __put_user(fp, &sf->fpu_save);
1da177e4 LT	384	} else {
	385	err \|= __put_user(0, &sf->fpu_save);
	386	}
5598473a DM	387	if (wsaved) {
	388	__siginfo_rwin_t *rwp = tail;
	389	tail += sizeof(*rwp);
	390	err \|= save_rwin_state(wsaved, rwp);
	391	err \|= __put_user(rwp, &sf->rwin_save);
	392	} else {
	393	err \|= __put_user(0, &sf->rwin_save);
	394	}
1da177e4 LT	395	err \|= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
	396
	397	/* Setup sigaltstack */
	398	err \|= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
	399	err \|= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
	400	err \|= __put_user(current->sas_ss_size, &sf->stack.ss_size);
	401
5598473a DM	402	if (!wsaved) {
	403	err \|= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
	404	sizeof(struct reg_window32));
	405	} else {
	406	struct reg_window32 *rp;
	407
	408	rp = &current_thread_info()->reg_window[wsaved - 1];
	409	err \|= __copy_to_user(sf, rp, sizeof(struct reg_window32));
	410	}
1da177e4 LT	411
	412	err \|= copy_siginfo_to_user(&sf->info, info);
	413
	414	if (err)
	415	goto sigsegv;
	416
	417	regs->u_regs[UREG_FP] = (unsigned long) sf;
	418	regs->u_regs[UREG_I0] = signo;
	419	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
	420	regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
	421
	422	regs->pc = (unsigned long) ka->sa.sa_handler;
	423	regs->npc = (regs->pc + 4);
	424
	425	if (ka->ka_restorer)
	426	regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
	427	else {
	428	regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
	429
	430	/* mov __NR_sigreturn, %g1 */
	431	err \|= __put_user(0x821020d8, &sf->insns[0]);
	432
	433	/* t 0x10 */
	434	err \|= __put_user(0x91d02010, &sf->insns[1]);
	435	if (err)
	436	goto sigsegv;
	437
	438	/* Flush instruction space. */
	439	flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
	440	}
392c2180	441	return 0;
1da177e4 LT	442
	443	sigill:
	444	do_exit(SIGILL);
392c2180 DM	445	return -EINVAL;
392c2180 DM	446
1da177e4 LT	447	sigsegv:
1da177e4 LT	448	force_sigsegv(signo, current);
392c2180	449	return -EFAULT;
1da177e4 LT	450	}
1da177e4 LT	451
392c2180	452	static inline int
1da177e4	453	handle_signal(unsigned long signr, struct k_sigaction *ka,
ec98c6b9	454	siginfo_t info, sigset_t oldset, struct pt_regs *regs)
1da177e4	455	{
392c2180 DM	456	int err;
392c2180 DM	457
ec98c6b9	458	if (ka->sa.sa_flags & SA_SIGINFO)
392c2180	459	err = setup_rt_frame(ka, regs, signr, oldset, info);
ec98c6b9	460	else
392c2180 DM	461	err = setup_frame(ka, regs, signr, oldset);
	462
	463	if (err)
	464	return err;
ec98c6b9	465
ce24d8a1	466	block_sigmask(ka, signr);
392c2180 DM	467	tracehook_signal_handler(signr, info, ka, regs, 0);
	468
	469	return 0;
1da177e4 LT	470	}
	471
	472	static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
	473	struct sigaction *sa)
	474	{
	475	switch(regs->u_regs[UREG_I0]) {
	476	case ERESTART_RESTARTBLOCK:
	477	case ERESTARTNOHAND:
	478	no_system_call_restart:
	479	regs->u_regs[UREG_I0] = EINTR;
	480	regs->psr \|= PSR_C;
	481	break;
	482	case ERESTARTSYS:
	483	if (!(sa->sa_flags & SA_RESTART))
	484	goto no_system_call_restart;
	485	/* fallthrough */
	486	case ERESTARTNOINTR:
	487	regs->u_regs[UREG_I0] = orig_i0;
	488	regs->pc -= 4;
	489	regs->npc -= 4;
	490	}
	491	}
	492
	493	/* Note that 'init' is a special process: it doesn't get signals it doesn't
	494	* want to handle. Thus you cannot kill init even with a SIGKILL even by
	495	* mistake.
	496	*/
5a157d5b	497	static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
1da177e4	498	{
1da177e4	499	struct k_sigaction ka;
28e61036	500	int restart_syscall;
2d7d5f05	501	sigset_t *oldset;
28e61036 DM	502	siginfo_t info;
28e61036 DM	503	int signr;
1da177e4	504
1d299bc7 DM	505	/* It's a lot of work and synchronization to add a new ptrace
	506	* register for GDB to save and restore in order to get
	507	* orig_i0 correct for syscall restarts when debugging.
	508	*
e88d2468 DM	509	* Although it should be the case that most of the global
	510	* registers are volatile across a system call, glibc already
	511	* depends upon that fact that we preserve them. So we can't
	512	* just use any global register to save away the orig_i0 value.
	513	*
	514	* In particular %g2, %g3, %g4, and %g5 are all assumed to be
	515	* preserved across a system call trap by various pieces of
	516	* code in glibc.
	517	*
	518	* %g7 is used as the "thread register". %g6 is not used in
	519	* any fixed manner. %g6 is used as a scratch register and
	520	* a compiler temporary, but it's value is never used across
	521	* a system call. Therefore %g6 is usable for orig_i0 storage.
1d299bc7	522	*/
28e61036	523	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
e88d2468	524	regs->u_regs[UREG_G6] = orig_i0;
1da177e4	525
2d7d5f05 DM	526	if (test_thread_flag(TIF_RESTORE_SIGMASK))
	527	oldset = &current->saved_sigmask;
	528	else
1da177e4 LT	529	oldset = &current->blocked;
1da177e4 LT	530
28e61036 DM	531	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
	532
	533	/* If the debugger messes with the program counter, it clears
	534	* the software "in syscall" bit, directing us to not perform
	535	* a syscall restart.
	536	*/
1d299bc7 DM	537	restart_syscall = 0;
	538	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
	539	restart_syscall = 1;
e88d2468	540	orig_i0 = regs->u_regs[UREG_G6];
1d299bc7 DM	541	}
1d299bc7 DM	542
28e61036	543
1da177e4	544	if (signr > 0) {
28e61036 DM	545	if (restart_syscall)
28e61036 DM	546	syscall_restart(orig_i0, regs, &ka.sa);
392c2180 DM	547	if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
	548	/* a signal was successfully delivered; the saved
	549	* sigmask will have been stored in the signal frame,
	550	* and will be restored by sigreturn, so we can simply
	551	* clear the TIF_RESTORE_SIGMASK flag.
	552	*/
	553	if (test_thread_flag(TIF_RESTORE_SIGMASK))
	554	clear_thread_flag(TIF_RESTORE_SIGMASK);
	555	}
2d7d5f05	556	return;
1da177e4	557	}
28e61036	558	if (restart_syscall &&
1da177e4 LT	559	(regs->u_regs[UREG_I0] == ERESTARTNOHAND \|\|
	560	regs->u_regs[UREG_I0] == ERESTARTSYS \|\|
	561	regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
	562	/* replay the system call when we are done */
28e61036	563	regs->u_regs[UREG_I0] = orig_i0;
1da177e4 LT	564	regs->pc -= 4;
1da177e4 LT	565	regs->npc -= 4;
c2785259	566	pt_regs_clear_syscall(regs);
1da177e4	567	}
28e61036	568	if (restart_syscall &&
1da177e4 LT	569	regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
	570	regs->u_regs[UREG_G1] = __NR_restart_syscall;
	571	regs->pc -= 4;
	572	regs->npc -= 4;
c2785259	573	pt_regs_clear_syscall(regs);
1da177e4	574	}
2d7d5f05 DM	575
	576	/* if there's no signal to deliver, we just put the saved sigmask
	577	* back
	578	*/
51a7b448	579	restore_saved_sigmask();
1da177e4 LT	580	}
1da177e4 LT	581
5a157d5b DM	582	void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
	583	unsigned long thread_info_flags)
	584	{
	585	if (thread_info_flags & (_TIF_SIGPENDING \| _TIF_RESTORE_SIGMASK))
	586	do_signal(regs, orig_i0);
	587	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
	588	clear_thread_flag(TIF_NOTIFY_RESUME);
	589	tracehook_notify_resume(regs);
	590	}
	591	}
	592
1da177e4 LT	593	asmlinkage int
	594	do_sys_sigstack(struct sigstack __user ssptr, struct sigstack __user ossptr,
	595	unsigned long sp)
	596	{
	597	int ret = -EFAULT;
	598
	599	/* First see if old state is wanted. */
	600	if (ossptr) {
	601	if (put_user(current->sas_ss_sp + current->sas_ss_size,
	602	&ossptr->the_stack) \|\|
	603	__put_user(on_sig_stack(sp), &ossptr->cur_status))
	604	goto out;
	605	}
	606
	607	/* Now see if we want to update the new state. */
	608	if (ssptr) {
	609	char *ss_sp;
	610
	611	if (get_user(ss_sp, &ssptr->the_stack))
	612	goto out;
	613	/* If the current stack was set with sigaltstack, don't
	614	swap stacks while we are on it. */
	615	ret = -EPERM;
	616	if (current->sas_ss_sp && on_sig_stack(sp))
	617	goto out;
	618
	619	/* Since we don't know the extent of the stack, and we don't
	620	track onstack-ness, but rather calculate it, we must
	621	presume a size. Ho hum this interface is lossy. */
	622	current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
	623	current->sas_ss_size = SIGSTKSZ;
	624	}
	625	ret = 0;
	626	out:
	627	return ret;
	628	}