ia32/os/sendsig.c

	sendsig.c revision a3c558251a68374a017f360afdc6c4f377a667ea
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */
/*  Copyright (c) 1984, 1986, 1987, 1988, 1989, 1990 AT&T   */
/*  All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/signal.h>
#include <sys/systm.h>
#include <sys/user.h>
#include <sys/mman.h>
#include <sys/class.h>
#include <sys/proc.h>
#include <sys/procfs.h>
#include <sys/buf.h>
#include <sys/kmem.h>
#include <sys/cred.h>
#include <sys/archsystm.h>
#include <sys/vmparam.h>
#include <sys/prsystm.h>
#include <sys/reboot.h>
#include <sys/uadmin.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/session.h>
#include <sys/ucontext.h>
#include <sys/dnlc.h>
#include <sys/var.h>
#include <sys/cmn_err.h>
#include <sys/debugreg.h>
#include <sys/thread.h>
#include <sys/vtrace.h>
#include <sys/consdev.h>
#include <sys/psw.h>
#include <sys/regset.h>

#include <sys/privregs.h>

#include <sys/stack.h>
#include <sys/swap.h>
#include <vm/hat.h>
#include <vm/anon.h>
#include <vm/as.h>
#include <vm/page.h>
#include <vm/seg.h>
#include <vm/seg_kmem.h>
#include <vm/seg_map.h>
#include <vm/seg_vn.h>
#include <sys/exec.h>
#include <sys/acct.h>
#include <sys/core.h>
#include <sys/corectl.h>
#include <sys/modctl.h>
#include <sys/tuneable.h>
#include <c2/audit.h>
#include <sys/bootconf.h>
#include <sys/dumphdr.h>
#include <sys/promif.h>
#include <sys/systeminfo.h>
#include <sys/kdi.h>
#include <sys/contract_impl.h>
#include <sys/x86_archext.h>

/*
 * Construct the execution environment for the user's signal
 * handler and arrange for control to be given to it on return
 * to userland.  The library code now calls setcontext() to
 * clean up after the signal handler, so sigret() is no longer
 * needed.
 *
 * (The various 'volatile' declarations are need to ensure that values
 * are correct on the error return from on_fault().)
 */

#if defined(__amd64)

/*
 * An amd64 signal frame looks like this on the stack:
 *
 * old %rsp:
 *      <128 bytes of untouched stack space>
 *      <a siginfo_t [optional]>
 *      <a ucontext_t>
 *      <siginfo_t *>
 *      <signal number>
 * new %rsp:    <return address (deliberately invalid)>
 *
 * The signal number and siginfo_t pointer are only pushed onto the stack in
 * order to allow stack backtraces.  The actual signal handling code expects the
 * arguments in registers.
 */

struct sigframe {
    caddr_t retaddr;
    long    signo;
    siginfo_t *sip;
};

int
sendsig(int sig, k_siginfo_t *sip, void (*hdlr)())
{
    volatile int minstacksz;
    int newstack;
    label_t ljb;
    volatile caddr_t sp;
    caddr_t fp;
    volatile struct regs *rp;
    volatile greg_t upc;
    volatile proc_t *p = ttoproc(curthread);
    klwp_t *lwp = ttolwp(curthread);
    ucontext_t *volatile tuc = NULL;
    ucontext_t *uc;
    siginfo_t *sip_addr;
    volatile int watched;

    /*
     * This routine is utterly dependent upon STACK_ALIGN being
     * 16 and STACK_ENTRY_ALIGN being 8. Let's just acknowledge
     * that and require it.
     */

#if STACK_ALIGN != 16 || STACK_ENTRY_ALIGN != 8
#error "sendsig() amd64 did not find the expected stack alignments"
#endif

    rp = lwptoregs(lwp);
    upc = rp->r_pc;

    /*
     * Since we're setting up to run the signal handler we have to
     * arrange that the stack at entry to the handler is (only)
     * STACK_ENTRY_ALIGN (i.e. 8) byte aligned so that when the handler
     * executes its push of %rbp, the stack realigns to STACK_ALIGN
     * (i.e. 16) correctly.
     *
     * The new sp will point to the sigframe and the ucontext_t. The
     * above means that sp (and thus sigframe) will be 8-byte aligned,
     * but not 16-byte aligned. ucontext_t, however, contains %xmm regs
     * which must be 16-byte aligned. Because of this, for correct
     * alignment, sigframe must be a multiple of 8-bytes in length, but
     * not 16-bytes. This will place ucontext_t at a nice 16-byte boundary.
     */

    /* LINTED: logical expression always true: op "||" */
    ASSERT((sizeof (struct sigframe) % 16) == 8);

    minstacksz = sizeof (struct sigframe) + SA(sizeof (*uc));
    if (sip != NULL)
        minstacksz += SA(sizeof (siginfo_t));
    ASSERT((minstacksz & (STACK_ENTRY_ALIGN - 1ul)) == 0);

    /*
     * Figure out whether we will be handling this signal on
     * an alternate stack specified by the user.  Then allocate
     * and validate the stack requirements for the signal handler
     * context.  on_fault will catch any faults.
     */
    newstack = sigismember(&u.u_sigonstack, sig) &&
        !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));

    if (newstack) {
        fp = (caddr_t)(SA((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
            SA(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN);
    } else {
        /*
         * Drop below the 128-byte reserved region of the stack frame
         * we're interrupting.
         */
        fp = (caddr_t)rp->r_sp - STACK_RESERVE;
    }

    /*
     * Force proper stack pointer alignment, even in the face of a
     * misaligned stack pointer from user-level before the signal.
     */
    fp = (caddr_t)((uintptr_t)fp & ~(STACK_ENTRY_ALIGN - 1ul));

    /*
     * Most of the time during normal execution, the stack pointer
     * is aligned on a STACK_ALIGN (i.e. 16 byte) boundary.  However,
     * (for example) just after a call instruction (which pushes
     * the return address), the callers stack misaligns until the
     * 'push %rbp' happens in the callee prolog.  So while we should
     * expect the stack pointer to be always at least STACK_ENTRY_ALIGN
     * aligned, we should -not- expect it to always be STACK_ALIGN aligned.
     * We now adjust to ensure that the new sp is aligned to
     * STACK_ENTRY_ALIGN but not to STACK_ALIGN.
     */
    sp = fp - minstacksz;
    if (((uintptr_t)sp & (STACK_ALIGN - 1ul)) == 0) {
        sp -= STACK_ENTRY_ALIGN;
        minstacksz = fp - sp;
    }

    /*
     * Now, make sure the resulting signal frame address is sane
     */
    if (sp >= (caddr_t)USERLIMIT || fp >= (caddr_t)USERLIMIT) {
#ifdef DEBUG
        printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
            PTOU(p)->u_comm, p->p_pid, sig);
        printf("sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
            (void *)sp, (void *)hdlr, (uintptr_t)upc);
        printf("sp above USERLIMIT\n");
#endif
        return (0);
    }

    watched = watch_disable_addr((caddr_t)sp, minstacksz, S_WRITE);

    if (on_fault(&ljb))
        goto badstack;

    if (sip != NULL) {
        zoneid_t zoneid;

        fp -= SA(sizeof (siginfo_t));
        uzero(fp, sizeof (siginfo_t));
        if (SI_FROMUSER(sip) &&
            (zoneid = p->p_zone->zone_id) != GLOBAL_ZONEID &&
            zoneid != sip->si_zoneid) {
            k_siginfo_t sani_sip = *sip;

            sani_sip.si_pid = p->p_zone->zone_zsched->p_pid;
            sani_sip.si_uid = 0;
            sani_sip.si_ctid = -1;
            sani_sip.si_zoneid = zoneid;
            copyout_noerr(&sani_sip, fp, sizeof (sani_sip));
        } else
            copyout_noerr(sip, fp, sizeof (*sip));
        sip_addr = (siginfo_t *)fp;

        if (sig == SIGPROF &&
            curthread->t_rprof != NULL &&
            curthread->t_rprof->rp_anystate) {
            /*
             * We stand on our head to deal with
             * the real time profiling signal.
             * Fill in the stuff that doesn't fit
             * in a normal k_siginfo structure.
             */
            int i = sip->si_nsysarg;

            while (--i >= 0)
                sulword_noerr(
                    (ulong_t *)&(sip_addr->si_sysarg[i]),
                    (ulong_t)lwp->lwp_arg[i]);
            copyout_noerr(curthread->t_rprof->rp_state,
                sip_addr->si_mstate,
                sizeof (curthread->t_rprof->rp_state));
        }
    } else
        sip_addr = NULL;

    /*
     * save the current context on the user stack directly after the
     * sigframe. Since sigframe is 8-byte-but-not-16-byte aligned,
     * and since sizeof (struct sigframe) is 24, this guarantees
     * 16-byte alignment for ucontext_t and its %xmm registers.
     */
    uc = (ucontext_t *)(sp + sizeof (struct sigframe));
    tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
    savecontext(tuc, lwp->lwp_sigoldmask);
    copyout_noerr(tuc, uc, sizeof (*tuc));
    kmem_free(tuc, sizeof (*tuc));
    tuc = NULL;

    lwp->lwp_oldcontext = (uintptr_t)uc;

    if (newstack) {
        lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
        if (lwp->lwp_ustack)
            copyout_noerr(&lwp->lwp_sigaltstack,
                (stack_t *)lwp->lwp_ustack, sizeof (stack_t));
    }

    /*
     * Set up signal handler return and stack linkage
     */
    {
        struct sigframe frame;

        /*
         * ensure we never return "normally"
         */
        frame.retaddr = (caddr_t)(uintptr_t)-1L;
        frame.signo = sig;
        frame.sip = sip_addr;
        copyout_noerr(&frame, sp, sizeof (frame));
    }

    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);

    /*
     * Set up user registers for execution of signal handler.
     */
    rp->r_sp = (greg_t)sp;
    rp->r_pc = (greg_t)hdlr;
    rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);

    rp->r_rdi = sig;
    rp->r_rsi = (uintptr_t)sip_addr;
    rp->r_rdx = (uintptr_t)uc;

    if ((rp->r_cs & 0xffff) != UCS_SEL ||
        (rp->r_ss & 0xffff) != UDS_SEL) {
        /*
         * Try our best to deliver the signal.
         */
        rp->r_cs = UCS_SEL;
        rp->r_ss = UDS_SEL;
    }

    /*
     * Don't set lwp_eosys here.  sendsig() is called via psig() after
     * lwp_eosys is handled, so setting it here would affect the next
     * system call.
     */
    return (1);

badstack:
    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
    if (tuc)
        kmem_free(tuc, sizeof (*tuc));
#ifdef DEBUG
    printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
        PTOU(p)->u_comm, p->p_pid, sig);
    printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
        (void *)sp, (void *)hdlr, (uintptr_t)upc);
#endif
    return (0);
}

#ifdef _SYSCALL32_IMPL

/*
 * An i386 SVR4/ABI signal frame looks like this on the stack:
 *
 * old %esp:
 *      <a siginfo32_t [optional]>
 *      <a ucontext32_t>
 *      <pointer to that ucontext32_t>
 *      <pointer to that siginfo32_t>
 *      <signo>
 * new %esp:    <return address (deliberately invalid)>
 */
struct sigframe32 {
    caddr32_t   retaddr;
    uint32_t    signo;
    caddr32_t   sip;
    caddr32_t   ucp;
};

int
sendsig32(int sig, k_siginfo_t *sip, void (*hdlr)())
{
    volatile int minstacksz;
    int newstack;
    label_t ljb;
    volatile caddr_t sp;
    caddr_t fp;
    volatile struct regs *rp;
    volatile greg_t upc;
    volatile proc_t *p = ttoproc(curthread);
    klwp_t *lwp = ttolwp(curthread);
    ucontext32_t *volatile tuc = NULL;
    ucontext32_t *uc;
    siginfo32_t *sip_addr;
    volatile int watched;

    rp = lwptoregs(lwp);
    upc = rp->r_pc;

    minstacksz = SA32(sizeof (struct sigframe32)) + SA32(sizeof (*uc));
    if (sip != NULL)
        minstacksz += SA32(sizeof (siginfo32_t));
    ASSERT((minstacksz & (STACK_ALIGN32 - 1)) == 0);

    /*
     * Figure out whether we will be handling this signal on
     * an alternate stack specified by the user.  Then allocate
     * and validate the stack requirements for the signal handler
     * context.  on_fault will catch any faults.
     */
    newstack = sigismember(&u.u_sigonstack, sig) &&
        !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));

    if (newstack) {
        fp = (caddr_t)(SA32((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
            SA32(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN32);
    } else if ((rp->r_ss & 0xffff) != UDS_SEL) {
        user_desc_t *ldt;
        /*
         * If the stack segment selector is -not- pointing at
         * the UDS_SEL descriptor and we have an LDT entry for
         * it instead, add the base address to find the effective va.
         */
        if ((ldt = p->p_ldt) != NULL)
            fp = (caddr_t)rp->r_sp +
                USEGD_GETBASE(&ldt[SELTOIDX(rp->r_ss)]);
        else
            fp = (caddr_t)rp->r_sp;
    } else
        fp = (caddr_t)rp->r_sp;

    /*
     * Force proper stack pointer alignment, even in the face of a
     * misaligned stack pointer from user-level before the signal.
     * Don't use the SA32() macro because that rounds up, not down.
     */
    fp = (caddr_t)((uintptr_t)fp & ~(STACK_ALIGN32 - 1));
    sp = fp - minstacksz;

    /*
     * Make sure lwp hasn't trashed its stack
     */
    if (sp >= (caddr_t)(uintptr_t)USERLIMIT32 ||
        fp >= (caddr_t)(uintptr_t)USERLIMIT32) {
#ifdef DEBUG
        printf("sendsig32: bad signal stack cmd=%s, pid=%d, sig=%d\n",
            PTOU(p)->u_comm, p->p_pid, sig);
        printf("sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
            (void *)sp, (void *)hdlr, (uintptr_t)upc);
        printf("sp above USERLIMIT\n");
#endif
        return (0);
    }

    watched = watch_disable_addr((caddr_t)sp, minstacksz, S_WRITE);

    if (on_fault(&ljb))
        goto badstack;

    if (sip != NULL) {
        siginfo32_t si32;
        zoneid_t zoneid;

        siginfo_kto32(sip, &si32);
        if (SI_FROMUSER(sip) &&
            (zoneid = p->p_zone->zone_id) != GLOBAL_ZONEID &&
            zoneid != sip->si_zoneid) {
            si32.si_pid = p->p_zone->zone_zsched->p_pid;
            si32.si_uid = 0;
            si32.si_ctid = -1;
            si32.si_zoneid = zoneid;
        }
        fp -= SA32(sizeof (si32));
        uzero(fp, sizeof (si32));
        copyout_noerr(&si32, fp, sizeof (si32));
        sip_addr = (siginfo32_t *)fp;

        if (sig == SIGPROF &&
            curthread->t_rprof != NULL &&
            curthread->t_rprof->rp_anystate) {
            /*
             * We stand on our head to deal with
             * the real-time profiling signal.
             * Fill in the stuff that doesn't fit
             * in a normal k_siginfo structure.
             */
            int i = sip->si_nsysarg;

            while (--i >= 0)
                suword32_noerr(&(sip_addr->si_sysarg[i]),
                    (uint32_t)lwp->lwp_arg[i]);
            copyout_noerr(curthread->t_rprof->rp_state,
                sip_addr->si_mstate,
                sizeof (curthread->t_rprof->rp_state));
        }
    } else
        sip_addr = NULL;

    /* save the current context on the user stack */
    fp -= SA32(sizeof (*tuc));
    uc = (ucontext32_t *)fp;
    tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
    savecontext32(tuc, lwp->lwp_sigoldmask);
    copyout_noerr(tuc, uc, sizeof (*tuc));
    kmem_free(tuc, sizeof (*tuc));
    tuc = NULL;

    lwp->lwp_oldcontext = (uintptr_t)uc;

    if (newstack) {
        lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
        if (lwp->lwp_ustack) {
            stack32_t stk32;

            stk32.ss_sp = (caddr32_t)(uintptr_t)
                lwp->lwp_sigaltstack.ss_sp;
            stk32.ss_size = (size32_t)
                lwp->lwp_sigaltstack.ss_size;
            stk32.ss_flags = (int32_t)
                lwp->lwp_sigaltstack.ss_flags;
            copyout_noerr(&stk32,
                (stack32_t *)lwp->lwp_ustack, sizeof (stk32));
        }
    }

    /*
     * Set up signal handler arguments
     */
    {
        struct sigframe32 frame32;

        frame32.sip = (caddr32_t)(uintptr_t)sip_addr;
        frame32.ucp = (caddr32_t)(uintptr_t)uc;
        frame32.signo = sig;
        frame32.retaddr = 0xffffffff;   /* never return! */
        copyout_noerr(&frame32, sp, sizeof (frame32));
    }

    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);

    rp->r_sp = (greg_t)(uintptr_t)sp;
    rp->r_pc = (greg_t)(uintptr_t)hdlr;
    rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);

    if ((rp->r_cs & 0xffff) != U32CS_SEL ||
        (rp->r_ss & 0xffff) != UDS_SEL) {
        /*
         * Try our best to deliver the signal.
         */
        rp->r_cs = U32CS_SEL;
        rp->r_ss = UDS_SEL;
    }

    /*
     * Don't set lwp_eosys here.  sendsig() is called via psig() after
     * lwp_eosys is handled, so setting it here would affect the next
     * system call.
     */
    return (1);

badstack:
    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
    if (tuc)
        kmem_free(tuc, sizeof (*tuc));
#ifdef DEBUG
    printf("sendsig32: bad signal stack cmd=%s pid=%d, sig=%d\n",
        PTOU(p)->u_comm, p->p_pid, sig);
    printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
        (void *)sp, (void *)hdlr, (uintptr_t)upc);
#endif
    return (0);
}

#endif  /* _SYSCALL32_IMPL */

#elif defined(__i386)

/*
 * An i386 SVR4/ABI signal frame looks like this on the stack:
 *
 * old %esp:
 *      <a siginfo32_t [optional]>
 *      <a ucontext32_t>
 *      <pointer to that ucontext32_t>
 *      <pointer to that siginfo32_t>
 *      <signo>
 * new %esp:    <return address (deliberately invalid)>
 */
struct sigframe {
    void        (*retaddr)();
    uint_t      signo;
    siginfo_t   *sip;
    ucontext_t  *ucp;
};

int
sendsig(int sig, k_siginfo_t *sip, void (*hdlr)())
{
    volatile int minstacksz;
    int newstack;
    label_t ljb;
    volatile caddr_t sp;
    caddr_t fp;
    struct regs *rp;
    volatile greg_t upc;
    volatile proc_t *p = ttoproc(curthread);
    klwp_t *lwp = ttolwp(curthread);
    ucontext_t *volatile tuc = NULL;
    ucontext_t *uc;
    siginfo_t *sip_addr;
    volatile int watched;

    rp = lwptoregs(lwp);
    upc = rp->r_pc;

    minstacksz = SA(sizeof (struct sigframe)) + SA(sizeof (*uc));
    if (sip != NULL)
        minstacksz += SA(sizeof (siginfo_t));
    ASSERT((minstacksz & (STACK_ALIGN - 1ul)) == 0);

    /*
     * Figure out whether we will be handling this signal on
     * an alternate stack specified by the user. Then allocate
     * and validate the stack requirements for the signal handler
     * context. on_fault will catch any faults.
     */
    newstack = sigismember(&u.u_sigonstack, sig) &&
        !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));

    if (newstack) {
        fp = (caddr_t)(SA((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
            SA(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN);
    } else if ((rp->r_ss & 0xffff) != UDS_SEL) {
        user_desc_t *ldt;
        /*
         * If the stack segment selector is -not- pointing at
         * the UDS_SEL descriptor and we have an LDT entry for
         * it instead, add the base address to find the effective va.
         */
        if ((ldt = p->p_ldt) != NULL)
            fp = (caddr_t)rp->r_sp +
                USEGD_GETBASE(&ldt[SELTOIDX(rp->r_ss)]);
        else
            fp = (caddr_t)rp->r_sp;
    } else
        fp = (caddr_t)rp->r_sp;

    /*
     * Force proper stack pointer alignment, even in the face of a
     * misaligned stack pointer from user-level before the signal.
     * Don't use the SA() macro because that rounds up, not down.
     */
    fp = (caddr_t)((uintptr_t)fp & ~(STACK_ALIGN - 1ul));
    sp = fp - minstacksz;

    /*
     * Make sure lwp hasn't trashed its stack.
     */
    if (sp >= (caddr_t)USERLIMIT || fp >= (caddr_t)USERLIMIT) {
#ifdef DEBUG
        printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
            PTOU(p)->u_comm, p->p_pid, sig);
        printf("sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
            (void *)sp, (void *)hdlr, (uintptr_t)upc);
        printf("sp above USERLIMIT\n");
#endif
        return (0);
    }

    watched = watch_disable_addr((caddr_t)sp, minstacksz, S_WRITE);

    if (on_fault(&ljb))
        goto badstack;

    if (sip != NULL) {
        zoneid_t zoneid;

        fp -= SA(sizeof (siginfo_t));
        uzero(fp, sizeof (siginfo_t));
        if (SI_FROMUSER(sip) &&
            (zoneid = p->p_zone->zone_id) != GLOBAL_ZONEID &&
            zoneid != sip->si_zoneid) {
            k_siginfo_t sani_sip = *sip;

            sani_sip.si_pid = p->p_zone->zone_zsched->p_pid;
            sani_sip.si_uid = 0;
            sani_sip.si_ctid = -1;
            sani_sip.si_zoneid = zoneid;
            copyout_noerr(&sani_sip, fp, sizeof (sani_sip));
        } else
            copyout_noerr(sip, fp, sizeof (*sip));
        sip_addr = (siginfo_t *)fp;

        if (sig == SIGPROF &&
            curthread->t_rprof != NULL &&
            curthread->t_rprof->rp_anystate) {
            /*
             * We stand on our head to deal with
             * the real time profiling signal.
             * Fill in the stuff that doesn't fit
             * in a normal k_siginfo structure.
             */
            int i = sip->si_nsysarg;

            while (--i >= 0)
                suword32_noerr(&(sip_addr->si_sysarg[i]),
                    (uint32_t)lwp->lwp_arg[i]);
            copyout_noerr(curthread->t_rprof->rp_state,
                sip_addr->si_mstate,
                sizeof (curthread->t_rprof->rp_state));
        }
    } else
        sip_addr = NULL;

    /* save the current context on the user stack */
    fp -= SA(sizeof (*tuc));
    uc = (ucontext_t *)fp;
    tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
    savecontext(tuc, lwp->lwp_sigoldmask);
    copyout_noerr(tuc, uc, sizeof (*tuc));
    kmem_free(tuc, sizeof (*tuc));
    tuc = NULL;

    lwp->lwp_oldcontext = (uintptr_t)uc;

    if (newstack) {
        lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
        if (lwp->lwp_ustack)
            copyout_noerr(&lwp->lwp_sigaltstack,
                (stack_t *)lwp->lwp_ustack, sizeof (stack_t));
    }

    /*
     * Set up signal handler arguments
     */
    {
        struct sigframe frame;

        frame.sip = sip_addr;
        frame.ucp = uc;
        frame.signo = sig;
        frame.retaddr = (void (*)())0xffffffff; /* never return! */
        copyout_noerr(&frame, sp, sizeof (frame));
    }

    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);

    rp->r_sp = (greg_t)sp;
    rp->r_pc = (greg_t)hdlr;
    rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);

    if ((rp->r_cs & 0xffff) != UCS_SEL ||
        (rp->r_ss & 0xffff) != UDS_SEL) {
        rp->r_cs = UCS_SEL;
        rp->r_ss = UDS_SEL;
    }

    /*
     * Don't set lwp_eosys here.  sendsig() is called via psig() after
     * lwp_eosys is handled, so setting it here would affect the next
     * system call.
     */
    return (1);

badstack:
    no_fault();
    if (watched)
        watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
    if (tuc)
        kmem_free(tuc, sizeof (*tuc));
#ifdef DEBUG
    printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
        PTOU(p)->u_comm, p->p_pid, sig);
    printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
        (void *)sp, (void *)hdlr, (uintptr_t)upc);
#endif
    return (0);
}

#endif  /* __i386 */