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/*

 *  linux/arch/m68knommu/platform/5307/signal.c

 *

 *  Copyright (C) 1998  D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,

 *                      Kenneth Albanowski <kjahds@kjahds.com>,

 *                      The Silver Hammer Group, Ltd.

 *

 *  Based on:

 *

 *  linux/arch/m68k/kernel/signal.c

 *

 *  Copyright (C) 1991, 1992  Linus Torvalds

 *

 * 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.

 */

/*

 * Linux/m68k support by Hamish Macdonald

 *

 * 68000 and CPU32 support D. Jeff Dionne

 * 68060 fixes by Jesper Skov

 * 5307  fixes by David W. Miller

 * ColdFire support by Greg Ungerer (gerg@moreton.com.au)

 */

/*

 * ++roman (07/09/96): implemented signal stacks (specially for tosemu on

 * Atari :-) Current limitation: Only one sigstack can be active at one time.

 * If a second signal with SA_STACK set arrives while working on a sigstack,

 * SA_STACK is ignored. This behaviour avoids lots of trouble with nested

 * signal handlers!

 */

#include <linux/config.h>

#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 <asm/setup.h>

#include <asm/segment.h>

#include <asm/pgtable.h>

#include <asm/traps.h>

/*

#define DEBUG

*/

#define offsetof(type, member)  ((size_t)(&((type *)0)->member))

#define _S(nr) (1<<((nr)-1))

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

asmlinkage int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options);

asmlinkage int do_signal(unsigned long oldmask, struct pt_regs *regs);

/*

 * atomically swap in the new signal mask, and wait for a signal.

 */

asmlinkage int do_sigsuspend(struct pt_regs *regs)

{

        unsigned long oldmask = current->blocked;

        unsigned long newmask = regs->d3;

        current->blocked = newmask & _BLOCKABLE;

        regs->d0 = -EINTR;

        while (1) {

                current->state = TASK_INTERRUPTIBLE;

                schedule();

                if (do_signal(oldmask, regs))

                        return -EINTR;

        }

}

asmlinkage int do_sigreturn(unsigned long __unused)

{

        struct sigcontext_struct context;

        struct pt_regs *regs;

        struct switch_stack *sw;

        int fsize = 0;

        unsigned long fp;

        unsigned long usp = rdusp();

#ifdef DEBUG

        printk("sys_sigreturn, usp=%08x\n", (unsigned) usp);

#endif

        /* get stack frame pointer */

        sw = (struct switch_stack *) &__unused;

        regs = (struct pt_regs *) (sw + 1);

        /* get previous context (including pointer to possible extra junk) */

        if (verify_area(VERIFY_READ, (void *)usp, sizeof(context)))

                goto badframe;

        memcpy_fromfs(&context,(void *)usp, sizeof(context));

        fp = usp + sizeof (context);

        /* restore signal mask */

        current->blocked = context.sc_mask & _BLOCKABLE;

        /* restore passed registers */

        regs->d0 = context.sc_d0;

        regs->d1 = context.sc_d1;

        regs->a0 = context.sc_a0;

        regs->a1 = context.sc_a1;

        regs->sr = (regs->sr & 0xff00) | (context.sc_sr & 0xff);

        regs->pc = context.sc_pc;

        regs->orig_d0 = -1;             /* disable syscall checks */

        wrusp(context.sc_usp);

        if (context.sc_usp != fp+fsize) {

#ifdef DEBUG

                printk("Stack off by %d\n",context.sc_usp - (fp+fsize));

#endif

                current->flags &= ~PF_ONSIGSTK;

        }

        return regs->d0;

badframe:

        do_exit(SIGSEGV);

}

/*

 * Set up a signal frame...

 *

 * This routine is somewhat complicated by the fact that if the

 * kernel may be entered by an exception other than a system call;

 * e.g. a bus error or other "bad" exception.  If this is the case,

 * then *all* the context on the kernel stack frame must be saved.

 *

 * For a large number of exceptions, the stack frame format is the same

 * as that which will be created when the process traps back to the kernel

 * when finished executing the signal handler.  In this case, nothing

 * must be done.  This is exception frame format "0".  For exception frame

 * formats "2", "9", "A" and "B", the extra information on the frame must

 * be saved.  This information is saved on the user stack and restored

 * when the signal handler is returned.

 *

 * The format of the user stack when executing the signal handler is:

 *

 *     usp ->  RETADDR (points to code below)

 *             signum  (parm #1)

 *             sigcode (parm #2 ; vector number)

 *             scp     (parm #3 ; sigcontext pointer, pointer to #1 below)

 *             code1   (addaw #20,sp) ; pop parms and code off stack

 *             code2   (moveq #119,d0; trap #0) ; sigreturn syscall

 *             slot1   (spare slots for ill-timed exception frame)

 *             slot2

 *     #1|     oldmask

 *       |     old usp

 *       |     d0      (first saved reg)

 *       |     d1

 *       |     a0

 *       |     a1

 *       |     sr      (saved status register)

 *       |     pc      (old pc; one to return to)

 * ----->|     forvec  (format and vector word of old supervisor stack frame)

 *       |     floating point context

 *

 * These are optionally followed by some extra stuff, depending on the

 * stack frame interrupted. This is 1 longword for format "2", 3

 * longwords for format "9", 6 longwords for format "A", and 21

 * longwords for format "B".

 *

 * everything after ------> is not present if the processor does not push a vector

 * format.  Only 68000 and the new 68000 modular core are like this

 */

#define UFRAME_SIZE(fs) (sizeof(struct sigcontext_struct)/4 + 8 + fs/4)

static void setup_frame (struct sigaction * sa, struct pt_regs *regs,

                         int signr, unsigned long oldmask)

{

        struct sigcontext_struct context;

        unsigned long *frame, *tframe;

        int stackOdd;

#define fsize 0

        frame = (unsigned long *)rdusp();

        stackOdd = !!(frame[-2] & 0x20000000);

        if (!(current->flags & PF_ONSIGSTK) && (sa->sa_flags & SA_STACK)) {

                frame = (unsigned long *)sa->sa_restorer;

                current->flags |= PF_ONSIGSTK;

        }

#ifdef DEBUG

printk("setup_frame: usp %.8x\n",frame);

#endif

        frame -= UFRAME_SIZE(fsize);

#ifdef DEBUG

printk("setup_frame: frame %.8x\n",frame);

#endif

        if (verify_area(VERIFY_WRITE,frame,UFRAME_SIZE(fsize)*4))

                do_exit(SIGSEGV);

        if (fsize) {

                memcpy_tofs (frame + UFRAME_SIZE(0), regs + 1, fsize);

                regs->stkadj = fsize;

        }

/* set up the "normal" stack seen by the signal handler */

        tframe = frame;

        /* return address points to code on stack */

        put_user((ulong)(frame+4), tframe); tframe++;

        if (current->exec_domain && current->exec_domain->signal_invmap)

            put_user(current->exec_domain->signal_invmap[signr], tframe);

        else

            put_user(signr, tframe);

        tframe++;

        tframe++;

        /* "scp" parameter.  points to sigcontext */

        put_user((ulong)(frame+6), tframe); tframe++;

        /* set up the return code... */

        /* Digestable ColdFire code :-) */

        if (!stackOdd)    /* moveq #28,d0; addal d0,sp */

                put_user(0x701cdfc0,tframe);

        else              /* moveq #30,d0; addal d0,sp */

                put_user(0x701edfc0,tframe);

        tframe++;

        put_user(0x70774e40,tframe); tframe++; /* moveq #119,d0; trap #0 */

        /*

         * Leave 2 empty slots between code and stack frame. If a real

         * interrupt comes in just before trap call we need space for

         * new exception frame (so it doesn't clobber code!)

         */

        put_user(0,tframe); tframe++; /* space for exception vector */

        put_user(0,tframe); tframe++; /* space for return address */

/* setup and copy the sigcontext structure */

        context.sc_mask       = oldmask;

        context.sc_usp        = rdusp();

        context.sc_d0         = regs->d0;

        context.sc_d1         = regs->d1;

        context.sc_a0         = regs->a0;

        context.sc_a1         = regs->a1;

        context.sc_sr         = regs->sr;

        context.sc_pc         = regs->pc;

        memcpy_tofs (tframe, &context, sizeof(context));

#ifdef DEBUG

printk("setup_frame: top tframe %.8x\n",tframe + sizeof(context));

#endif

        /* Set up registers for signal handler */

        wrusp ((unsigned long) frame);

        regs->pc = (unsigned long) sa->sa_handler;

        /* Prepare to skip over the extra stuff in the exception frame.  */

        if (regs->stkadj) {

                struct pt_regs *tregs =

                        (struct pt_regs *)((ulong)regs + regs->stkadj);

#ifdef DEBUG

                printk("Performing stackadjust=%04x\n", regs->stkadj);

#endif

                /* This must be copied with decreasing addresses to

                   handle overlaps.  */

                tregs->pc = regs->pc;

                tregs->sr = regs->sr;

        }

}

/*

 * OK, we're invoking a handler

 */

static void handle_signal(unsigned long signr, struct sigaction *sa,

                          unsigned long oldmask, struct pt_regs *regs)

{

#ifdef DEBUG

        printk("Entering handle_signal, signr=%d\n", signr);

#endif

        /* are we from a system call? */

        if (regs->orig_d0 >= 0) {

                /* If so, check system call restarting.. */

                switch (regs->d0) {

                        case -ERESTARTNOHAND:

                                regs->d0 = -EINTR;

                                break;

                        case -ERESTARTSYS:

                                if (!(sa->sa_flags & SA_RESTART)) {

                                        regs->d0 = -EINTR;

                                        break;

                                }

                /* fallthrough */

                        case -ERESTARTNOINTR:

                                regs->d0 = regs->orig_d0;

                                regs->pc -= 2;

                }

        }

        /* set up the stack frame */

        setup_frame(sa, regs, signr, oldmask);

        if (sa->sa_flags & SA_ONESHOT)

                sa->sa_handler = NULL;

        if (!(sa->sa_flags & SA_NOMASK))

                current->blocked |= (sa->sa_mask | _S(signr)) & _BLOCKABLE;

}

/*

 * 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.

 *

 * Note that we go through the signals twice: once to check the signals

 * that the kernel can handle, and then we build all the user-level signal

 * handling stack-frames in one go after that.

 */

asmlinkage int do_signal(unsigned long oldmask, struct pt_regs *regs)

{

        unsigned long mask = ~current->blocked;

        unsigned long signr;

        struct sigaction * sa;

        current->tss.esp0 = (unsigned long) regs;

        /* If the process is traced, all signals are passed to the debugger. */

        if (current->flags & PF_PTRACED)

                mask = ~0UL;

        while ((signr = current->signal & mask) != 0) {

                signr = ffz(~signr);

                clear_bit(signr, &current->signal);

                sa = current->sig->action + signr;

#ifdef DEBUG

                printk("Signal %d, Handler %d: ", signr, sa->sa_handler);

#endif

                signr++;

                if ((current->flags & PF_PTRACED) && signr != SIGKILL) {

                        current->exit_code = signr;

                        current->state = TASK_STOPPED;

                        /* Did we come from a system call? */

                        if (regs->orig_d0 >= 0) {

                                /* Restart the system call */

                                if (regs->d0 == -ERESTARTNOHAND ||

                                    regs->d0 == -ERESTARTSYS ||

                                    regs->d0 == -ERESTARTNOINTR) {

                                        regs->d0 = regs->orig_d0;

                                        regs->pc -= 2;

                                }

                        }

                        notify_parent(current, SIGCHLD);

                        schedule();

                        if (!(signr = current->exit_code)) {

                            discard_frame:

                            continue;

                        }

                        current->exit_code = 0;

                        if (signr == SIGSTOP)

                                goto discard_frame;

                        if (_S(signr) & current->blocked) {

                                current->signal |= _S(signr);

                                mask &= ~_S(signr);

                                continue;

                        }

                        sa = current->sig->action + signr - 1;

                }

                if (sa->sa_handler == SIG_IGN) {

#ifdef DEBUG

                        printk("Ignoring.\n");

#endif

                        if (signr != SIGCHLD)

                                continue;

                        /* check for SIGCHLD: it's special */

                        while (sys_waitpid(-1,NULL,WNOHANG) > 0)

                                /* nothing */;

                        continue;

                }

                if (sa->sa_handler == SIG_DFL) {

#ifdef DEBUG

                        printk("Default.\n");

#endif

                        if (current->pid == 1)

                                continue;

                        switch (signr) {

                        case SIGCONT: case SIGCHLD: case SIGWINCH:

                                continue;

                        case SIGTSTP: case SIGTTIN: case SIGTTOU:

                                if (is_orphaned_pgrp(current->pgrp))

                                        continue;

                        case SIGSTOP:

                                if (current->flags & PF_PTRACED)

                                        continue;

                                current->state = TASK_STOPPED;

                                current->exit_code = signr;

                                if (!(current->p_pptr->sig->action[SIGCHLD-1].sa_flags &

                                      SA_NOCLDSTOP))

                                        notify_parent(current, SIGCHLD);

                                schedule();

                                continue;

                        case SIGQUIT: case SIGILL: case SIGTRAP:

                        case SIGIOT: case SIGFPE: case SIGSEGV:

                                if (current->binfmt && current->binfmt->core_dump) {

                                    if (current->binfmt->core_dump(signr, regs))

                                        signr |= 0x80;

                                }

                                /* fall through */

                        default:

                                current->signal |= _S(signr & 0x7f);

                                current->flags |= PF_SIGNALED;

                                do_exit(signr);

                        }

                }

                handle_signal(signr, sa, oldmask, regs);

                return 1;

        }

        /* Did we come from a system call? */

        if (regs->orig_d0 >= 0) {

                /* Restart the system call - no handlers present */

                if (regs->d0 == -ERESTARTNOHAND ||

                    regs->d0 == -ERESTARTSYS ||

                    regs->d0 == -ERESTARTNOINTR) {

                        regs->d0 = regs->orig_d0;

                        regs->pc -= 2;

                }

        }

        /* If we are about to discard some frame stuff we must copy

           over the remaining frame. */

        if (regs->stkadj) {

                struct pt_regs *tregs =

                  (struct pt_regs *) ((ulong) regs + regs->stkadj);

#ifdef DEBUG

        printk("!!!!!!!!!!!!!! stkadj !!!\n");

#endif

                /* This must be copied with decreasing addresses to

                   handle overlaps.  */

                tregs->pc = regs->pc;

                tregs->sr = regs->sr;

        }

        return 0;

}