/*      $NetBSD: context.S,v 1.9 2023/10/06 11:45:16 skrll Exp $        */

/*
 * Copyright (c) 2003 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD: releng/10.1/sys/ia64/ia64/context.S 204184 2010-02-22 01:23:41Z marcel $
 */

#include <machine/asm.h>
#include "assym.h"

        .text

/*
 * void restorectx(struct pcb *)
 */
ENTRY(restorectx, 1)
{       .mmi
        invala
        mov             ar.rsc=0
        add             r31=8,r32
        ;;
}
{       .mmi
        ld8             r12=[r32]               // sp
        ld8             r16=[r31],16            // unat (before)
        add             r30=16,r32
        ;;
}
{       .mmi
        ld8             r17=[r30],16            // rp
        ld8             r18=[r31],16            // pr
        add             r14=SIZEOF_SPECIAL,r32
        ;;
}
{       .mmi
        ld8             r19=[r30],16            // pfs
        ld8             r20=[r31],16            // bspstore
        mov             rp=r17
        ;;
}
{       .mmi
        loadrs
        ld8             r21=[r30],16            // rnat
        mov             pr=r18,0x1fffe
        ;;
}
{       .mmi
        ld8             r17=[r14],8             // unat (after)
        mov             ar.bspstore=r20
        mov             ar.pfs=r19
        ;;
}
{       .mmi
        mov             ar.unat=r17
        mov             ar.rnat=r21
        add             r15=8,r14
        ;;
}
{       .mmi
        ld8.fill        r4=[r14],16             // r4
        ld8.fill        r5=[r15],16             // r5
        nop             0
        ;;
}
{       .mmi
        ld8.fill        r6=[r14],16             // r6
        ld8.fill        r7=[r15],16             // r7
        nop             0
        ;;
}
{       .mmi
        mov             ar.unat=r16
        mov             ar.rsc=3
        nop             0
}
{       .mmi
        ld8             r17=[r14],16            // b1
        ld8             r18=[r15],16            // b2
        nop             0
        ;;
}
{       .mmi
        ld8             r19=[r14],16            // b3
        ld8             r20=[r15],16            // b4
        mov             b1=r17
        ;;
}
{       .mmi
        ld8             r16=[r14],24            // b5
        ld8             r17=[r15],32            // lc
        mov             b2=r18
        ;;
}
{       .mmi
        ldf.fill        f2=[r14],32
        ldf.fill        f3=[r15],32
        mov             b3=r19
        ;;
}
{       .mmi
        ldf.fill        f4=[r14],32
        ldf.fill        f5=[r15],32
        mov             b4=r20
        ;;
}
{       .mmi
        ldf.fill        f16=[r14],32
        ldf.fill        f17=[r15],32
        mov             b5=r16
        ;;
}
{       .mmi
        ldf.fill        f18=[r14],32
        ldf.fill        f19=[r15],32
        mov             ar.lc=r17
        ;;
}
        ldf.fill        f20=[r14],32
        ldf.fill        f21=[r15],32
        ;;
        ldf.fill        f22=[r14],32
        ldf.fill        f23=[r15],32
        ;;
        ldf.fill        f24=[r14],32
        ldf.fill        f25=[r15],32
        ;;
        ldf.fill        f26=[r14],32
        ldf.fill        f27=[r15],32
        ;;
{       .mmi
        ldf.fill        f28=[r14],32
        ldf.fill        f29=[r15],32
        add             r8=1,r0
        ;;
}
{       .mmb
        ldf.fill        f30=[r14]
        ldf.fill        f31=[r15]
        br.ret.sptk     rp
        ;;
}
END(restorectx)

/*
 * void swapctx(struct pcb *old, struct pcb *new)
 */

ENTRY(swapctx, 2)
{       .mmi
        mov             ar.rsc=0
        mov             r16=ar.unat
        add             r31=8,r32
        ;;
}
{       .mmi
        flushrs
        st8             [r32]=sp,16             // sp
        mov             r17=rp
        ;;
}
{       .mmi
        st8             [r31]=r16,16            // unat (before)
        st8             [r32]=r17,16            // rp
        mov             r16=pr
        ;;
}
{       .mmi
        st8             [r31]=r16,16            // pr
        mov             r17=ar.bsp
        mov             r16=ar.pfs
        ;;
}
{       .mmi
        st8             [r32]=r16,16            // pfs
        st8             [r31]=r17,16            // bspstore
        cmp.eq          p15,p0=0,r33
        ;;
}
{       .mmi
        mov             r16=ar.rnat
(p15)   mov             ar.rsc=3
        add             r30=SIZEOF_SPECIAL-(6*8),r32
        ;;
}
{       .mmi
        st8             [r32]=r16,SIZEOF_SPECIAL-(4*8)          // rnat
        st8             [r31]=r0,SIZEOF_SPECIAL-(6*8)           // __spare
        mov             r16=b1
        ;;
}
        /* callee_saved */
{       .mmi
        .mem.offset     8,0
        st8.spill       [r31]=r4,16             // r4
        .mem.offset     16,0
        st8.spill       [r32]=r5,16             // r5
        mov             r17=b2
        ;;
}
{       .mmi
        .mem.offset     24,0
        st8.spill       [r31]=r6,16             // r6
        .mem.offset     32,0
        st8.spill       [r32]=r7,16             // r7
        mov             r18=b3
        ;;
}
{       .mmi
        st8             [r31]=r16,16            // b1
        mov             r16=ar.unat
        mov             r19=b4
        ;;
}
{       .mmi
        st8             [r30]=r16               // unat (after)
        st8             [r32]=r17,16            // b2
        mov             r16=b5
        ;;
}
{       .mmi
        st8             [r31]=r18,16            // b3
        st8             [r32]=r19,16            // b4
        mov             r17=ar.lc
        ;;
}
        st8             [r31]=r16,16            // b5
        st8             [r32]=r17,16            // lc
        ;;
        st8             [r31]=r0,24             // __spare
        stf.spill       [r32]=f2,32
        ;;
        stf.spill       [r31]=f3,32
        stf.spill       [r32]=f4,32
        ;;
        stf.spill       [r31]=f5,32
        stf.spill       [r32]=f16,32
        ;;
        stf.spill       [r31]=f17,32
        stf.spill       [r32]=f18,32
        ;;
        stf.spill       [r31]=f19,32
        stf.spill       [r32]=f20,32
        ;;
        stf.spill       [r31]=f21,32
        stf.spill       [r32]=f22,32
        ;;
        stf.spill       [r31]=f23,32
        stf.spill       [r32]=f24,32
        ;;
        stf.spill       [r31]=f25,32
        stf.spill       [r32]=f26,32
        ;;
        stf.spill       [r31]=f27,32
        stf.spill       [r32]=f28,32
        ;;
{       .mmi
        stf.spill       [r31]=f29,32
        stf.spill       [r32]=f30
(p15)   add             r8=0,r0
        ;;
}
{       .mmb
        stf.spill       [r31]=f31
        mf
(p15)   br.ret.sptk     rp
        ;;
}
{       .mib
        mov             r32=r33
        nop             0
        br.sptk         restorectx
        ;;
}
END(swapctx)

/*
 * save_callee_saved(struct _callee_saved *)
 */
ENTRY(save_callee_saved, 1)
{       .mii
        nop             0
        add             r14=8,r32
        add             r15=16,r32
        ;;
}
{       .mmi
        .mem.offset     8,0
        st8.spill       [r14]=r4,16             // r4
        .mem.offset     16,0
        st8.spill       [r15]=r5,16             // r5
        mov             r16=b1
        ;;
}
{       .mmi
        .mem.offset     24,0
        st8.spill       [r14]=r6,16             // r6
        .mem.offset     32,0
        st8.spill       [r15]=r7,16             // r7
        mov             r17=b2
        ;;
}
{       .mmi
        st8             [r14]=r16,16            // b1
        mov             r18=ar.unat
        mov             r19=b3
        ;;
}
{       .mmi
        st8             [r32]=r18               // nat (after)
        st8             [r15]=r17,16            // b2
        mov             r16=b4
        ;;
}
{       .mmi
        st8             [r14]=r19,16            // b3
        st8             [r15]=r16,16            // b4
        mov             r17=b5
        ;;
}
{       .mii
        st8             [r14]=r17,16            // b5
        mov             r16=ar.lc
        nop             0
        ;;
}
{       .mmb
        st8             [r15]=r16               // ar.lc
        st8             [r14]=r0                // __spare
        br.ret.sptk     rp
        ;;
}
END(save_callee_saved)

/*
 * restore_callee_saved(struct _callee_saved *)
 */
ENTRY(restore_callee_saved, 1)
{       .mmi
        ld8             r30=[r32],16            // nat (after)
        ;;
        mov             ar.unat=r30
        add             r31=-8,r32
        ;;
}
{       .mmi
        ld8.fill        r4=[r31],16             // r4
        ld8.fill        r5=[r32],16             // r5
        nop             0
        ;;
}
{       .mmi
        ld8.fill        r6=[r31],16             // r6
        ld8.fill        r7=[r32],16             // r7
        nop             0
        ;;
}
{       .mmi
        ld8             r30=[r31],16            // b1
        ld8             r29=[r32],16            // b2
        nop             0
        ;;
}
{       .mmi
        ld8             r28=[r31],16            // b3
        ld8             r27=[r32],16            // b4
        mov             b1=r30
        ;;
}
{       .mii
        ld8             r26=[r31]               // b5
        mov             b2=r29
        mov             b3=r28
        ;;
}
{       .mii
        ld8             r25=[r32]               // lc
        mov             b4=r27
        mov             b5=r26
        ;;
}
{       .mib
        nop             0
        mov             ar.lc=r25
        br.ret.sptk     rp
        ;;
}
END(restore_callee_saved)

/*
 * save_callee_saved_fp(struct _callee_saved_fp *)
 */
ENTRY(save_callee_saved_fp, 1)
        add             r31=16,r32
        stf.spill       [r32]=f2,32
        ;;
        stf.spill       [r31]=f3,32
        stf.spill       [r32]=f4,32
        ;;
        stf.spill       [r31]=f5,32
        stf.spill       [r32]=f16,32
        ;;
        stf.spill       [r31]=f17,32
        stf.spill       [r32]=f18,32
        ;;
        stf.spill       [r31]=f19,32
        stf.spill       [r32]=f20,32
        ;;
        stf.spill       [r31]=f21,32
        stf.spill       [r32]=f22,32
        ;;
        stf.spill       [r31]=f23,32
        stf.spill       [r32]=f24,32
        ;;
        stf.spill       [r31]=f25,32
        stf.spill       [r32]=f26,32
        ;;
        stf.spill       [r31]=f27,32
        stf.spill       [r32]=f28,32
        ;;
        stf.spill       [r31]=f29,32
        stf.spill       [r32]=f30
        ;;
        stf.spill       [r31]=f31
        br.ret.sptk     rp
        ;;
END(save_callee_saved_fp)

/*
 * restore_callee_saved_fp(struct _callee_saved_fp *)
 */
ENTRY(restore_callee_saved_fp, 1)
        add             r31=16,r32
        ldf.fill        f2=[r32],32
        ;;
        ldf.fill        f3=[r31],32
        ldf.fill        f4=[r32],32
        ;;
        ldf.fill        f5=[r31],32
        ldf.fill        f16=[r32],32
        ;;
        ldf.fill        f17=[r31],32
        ldf.fill        f18=[r32],32
        ;;
        ldf.fill        f19=[r31],32
        ldf.fill        f20=[r32],32
        ;;
        ldf.fill        f21=[r31],32
        ldf.fill        f22=[r32],32
        ;;
        ldf.fill        f23=[r31],32
        ldf.fill        f24=[r32],32
        ;;
        ldf.fill        f25=[r31],32
        ldf.fill        f26=[r32],32
        ;;
        ldf.fill        f27=[r31],32
        ldf.fill        f28=[r32],32
        ;;
        ldf.fill        f29=[r31],32
        ldf.fill        f30=[r32]
        ;;
        ldf.fill        f31=[r31]
        br.ret.sptk     rp
        ;;
END(restore_callee_saved_fp)

/*
 * save_high_fp(struct _high_fp *)
 */
ENTRY(save_high_fp, 1)
        rsm             psr.dfh
        ;;
        srlz.d
        add             r31=16,r32
        stf.spill       [r32]=f32,32
        ;;
        stf.spill       [r31]=f33,32
        stf.spill       [r32]=f34,32
        ;;
        stf.spill       [r31]=f35,32
        stf.spill       [r32]=f36,32
        ;;
        stf.spill       [r31]=f37,32
        stf.spill       [r32]=f38,32
        ;;
        stf.spill       [r31]=f39,32
        stf.spill       [r32]=f40,32
        ;;
        stf.spill       [r31]=f41,32
        stf.spill       [r32]=f42,32
        ;;
        stf.spill       [r31]=f43,32
        stf.spill       [r32]=f44,32
        ;;
        stf.spill       [r31]=f45,32
        stf.spill       [r32]=f46,32
        ;;
        stf.spill       [r31]=f47,32
        stf.spill       [r32]=f48,32
        ;;
        stf.spill       [r31]=f49,32
        stf.spill       [r32]=f50,32
        ;;
        stf.spill       [r31]=f51,32
        stf.spill       [r32]=f52,32
        ;;
        stf.spill       [r31]=f53,32
        stf.spill       [r32]=f54,32
        ;;
        stf.spill       [r31]=f55,32
        stf.spill       [r32]=f56,32
        ;;
        stf.spill       [r31]=f57,32
        stf.spill       [r32]=f58,32
        ;;
        stf.spill       [r31]=f59,32
        stf.spill       [r32]=f60,32
        ;;
        stf.spill       [r31]=f61,32
        stf.spill       [r32]=f62,32
        ;;
        stf.spill       [r31]=f63,32
        stf.spill       [r32]=f64,32
        ;;
        stf.spill       [r31]=f65,32
        stf.spill       [r32]=f66,32
        ;;
        stf.spill       [r31]=f67,32
        stf.spill       [r32]=f68,32
        ;;
        stf.spill       [r31]=f69,32
        stf.spill       [r32]=f70,32
        ;;
        stf.spill       [r31]=f71,32
        stf.spill       [r32]=f72,32
        ;;
        stf.spill       [r31]=f73,32
        stf.spill       [r32]=f74,32
        ;;
        stf.spill       [r31]=f75,32
        stf.spill       [r32]=f76,32
        ;;
        stf.spill       [r31]=f77,32
        stf.spill       [r32]=f78,32
        ;;
        stf.spill       [r31]=f79,32
        stf.spill       [r32]=f80,32
        ;;
        stf.spill       [r31]=f81,32
        stf.spill       [r32]=f82,32
        ;;
        stf.spill       [r31]=f83,32
        stf.spill       [r32]=f84,32
        ;;
        stf.spill       [r31]=f85,32
        stf.spill       [r32]=f86,32
        ;;
        stf.spill       [r31]=f87,32
        stf.spill       [r32]=f88,32
        ;;
        stf.spill       [r31]=f89,32
        stf.spill       [r32]=f90,32
        ;;
        stf.spill       [r31]=f91,32
        stf.spill       [r32]=f92,32
        ;;
        stf.spill       [r31]=f93,32
        stf.spill       [r32]=f94,32
        ;;
        stf.spill       [r31]=f95,32
        stf.spill       [r32]=f96,32
        ;;
        stf.spill       [r31]=f97,32
        stf.spill       [r32]=f98,32
        ;;
        stf.spill       [r31]=f99,32
        stf.spill       [r32]=f100,32
        ;;
        stf.spill       [r31]=f101,32
        stf.spill       [r32]=f102,32
        ;;
        stf.spill       [r31]=f103,32
        stf.spill       [r32]=f104,32
        ;;
        stf.spill       [r31]=f105,32
        stf.spill       [r32]=f106,32
        ;;
        stf.spill       [r31]=f107,32
        stf.spill       [r32]=f108,32
        ;;
        stf.spill       [r31]=f109,32
        stf.spill       [r32]=f110,32
        ;;
        stf.spill       [r31]=f111,32
        stf.spill       [r32]=f112,32
        ;;
        stf.spill       [r31]=f113,32
        stf.spill       [r32]=f114,32
        ;;
        stf.spill       [r31]=f115,32
        stf.spill       [r32]=f116,32
        ;;
        stf.spill       [r31]=f117,32
        stf.spill       [r32]=f118,32
        ;;
        stf.spill       [r31]=f119,32
        stf.spill       [r32]=f120,32
        ;;
        stf.spill       [r31]=f121,32
        stf.spill       [r32]=f122,32
        ;;
        stf.spill       [r31]=f123,32
        stf.spill       [r32]=f124,32
        ;;
        stf.spill       [r31]=f125,32
        stf.spill       [r32]=f126
        ;;
        stf.spill       [r31]=f127
        ssm             psr.dfh
        ;;
        srlz.d
        br.ret.sptk     rp
        ;;
END(save_high_fp)

/*
 * restore_high_fp(struct _high_fp *)
 */
ENTRY(restore_high_fp, 1)
        rsm             psr.dfh
        ;;
        srlz.d
        add             r31=16,r32
        ldf.fill        f32=[r32],32
        ;;
        ldf.fill        f33=[r31],32
        ldf.fill        f34=[r32],32
        ;;
        ldf.fill        f35=[r31],32
        ldf.fill        f36=[r32],32
        ;;
        ldf.fill        f37=[r31],32
        ldf.fill        f38=[r32],32
        ;;
        ldf.fill        f39=[r31],32
        ldf.fill        f40=[r32],32
        ;;
        ldf.fill        f41=[r31],32
        ldf.fill        f42=[r32],32
        ;;
        ldf.fill        f43=[r31],32
        ldf.fill        f44=[r32],32
        ;;
        ldf.fill        f45=[r31],32
        ldf.fill        f46=[r32],32
        ;;
        ldf.fill        f47=[r31],32
        ldf.fill        f48=[r32],32
        ;;
        ldf.fill        f49=[r31],32
        ldf.fill        f50=[r32],32
        ;;
        ldf.fill        f51=[r31],32
        ldf.fill        f52=[r32],32
        ;;
        ldf.fill        f53=[r31],32
        ldf.fill        f54=[r32],32
        ;;
        ldf.fill        f55=[r31],32
        ldf.fill        f56=[r32],32
        ;;
        ldf.fill        f57=[r31],32
        ldf.fill        f58=[r32],32
        ;;
        ldf.fill        f59=[r31],32
        ldf.fill        f60=[r32],32
        ;;
        ldf.fill        f61=[r31],32
        ldf.fill        f62=[r32],32
        ;;
        ldf.fill        f63=[r31],32
        ldf.fill        f64=[r32],32
        ;;
        ldf.fill        f65=[r31],32
        ldf.fill        f66=[r32],32
        ;;
        ldf.fill        f67=[r31],32
        ldf.fill        f68=[r32],32
        ;;
        ldf.fill        f69=[r31],32
        ldf.fill        f70=[r32],32
        ;;
        ldf.fill        f71=[r31],32
        ldf.fill        f72=[r32],32
        ;;
        ldf.fill        f73=[r31],32
        ldf.fill        f74=[r32],32
        ;;
        ldf.fill        f75=[r31],32
        ldf.fill        f76=[r32],32
        ;;
        ldf.fill        f77=[r31],32
        ldf.fill        f78=[r32],32
        ;;
        ldf.fill        f79=[r31],32
        ldf.fill        f80=[r32],32
        ;;
        ldf.fill        f81=[r31],32
        ldf.fill        f82=[r32],32
        ;;
        ldf.fill        f83=[r31],32
        ldf.fill        f84=[r32],32
        ;;
        ldf.fill        f85=[r31],32
        ldf.fill        f86=[r32],32
        ;;
        ldf.fill        f87=[r31],32
        ldf.fill        f88=[r32],32
        ;;
        ldf.fill        f89=[r31],32
        ldf.fill        f90=[r32],32
        ;;
        ldf.fill        f91=[r31],32
        ldf.fill        f92=[r32],32
        ;;
        ldf.fill        f93=[r31],32
        ldf.fill        f94=[r32],32
        ;;
        ldf.fill        f95=[r31],32
        ldf.fill        f96=[r32],32
        ;;
        ldf.fill        f97=[r31],32
        ldf.fill        f98=[r32],32
        ;;
        ldf.fill        f99=[r31],32
        ldf.fill        f100=[r32],32
        ;;
        ldf.fill        f101=[r31],32
        ldf.fill        f102=[r32],32
        ;;
        ldf.fill        f103=[r31],32
        ldf.fill        f104=[r32],32
        ;;
        ldf.fill        f105=[r31],32
        ldf.fill        f106=[r32],32
        ;;
        ldf.fill        f107=[r31],32
        ldf.fill        f108=[r32],32
        ;;
        ldf.fill        f109=[r31],32
        ldf.fill        f110=[r32],32
        ;;
        ldf.fill        f111=[r31],32
        ldf.fill        f112=[r32],32
        ;;
        ldf.fill        f113=[r31],32
        ldf.fill        f114=[r32],32
        ;;
        ldf.fill        f115=[r31],32
        ldf.fill        f116=[r32],32
        ;;
        ldf.fill        f117=[r31],32
        ldf.fill        f118=[r32],32
        ;;
        ldf.fill        f119=[r31],32
        ldf.fill        f120=[r32],32
        ;;
        ldf.fill        f121=[r31],32
        ldf.fill        f122=[r32],32
        ;;
        ldf.fill        f123=[r31],32
        ldf.fill        f124=[r32],32
        ;;
        ldf.fill        f125=[r31],32
        ldf.fill        f126=[r32]
        ;;
        ldf.fill        f127=[r31]
        ssm             psr.dfh
        ;;
        srlz.d
        br.ret.sptk     rp
        ;;
END(restore_high_fp)

/*
 * lwp_trampoline()
 *
 * Arrange for a function to be invoked neatly, after a cpu_switchto().
 *
 * Invokes fork_exit() passing in three arguments: a callout function, an
 * argument to the callout, and a trapframe pointer.  For child processes
 * returning from fork(2), the argument is a pointer to the child process.
 *
 * The callout function and its argument is in the trapframe in scratch
 * registers r2 and r3.
 */
ENTRY(lwp_trampoline, 0)
        .prologue
        .save   rp,r0

        .body
{       .mmi
        alloc           r14=ar.pfs,0,1,2,0
        add             r2=PC_CURLWP,r13        // r2 = &ci->ci_curlwp
        ;;
}
{       .mmi
        mov             out0=ret1               // oldlwp
        ld8             out1=[r2]               // newlwp = ci->ci_curlwp
        add             loc0=32+SIZEOF_SPECIAL+8,sp     // tf_scratch.gr2(func)
        ;;
}
{       .mmb
        ld8             loc0=[loc0]
        add             r4=32+SIZEOF_SPECIAL+16,sp      // tf_scratch.gr3(arg)
        br.call.sptk    rp=_C_LABEL(lwp_startup)
        ;;
}
{       .mib
        ld8             out0=[r4]
        mov             b1=loc0
        br.call.sptk    rp=b1
        ;;
}
        /*
         * If we get back here, it means we're a user space process that's
         * the immediate result of fork(2).
         */
        .global         enter_userland
        .type           enter_userland, @function
enter_userland:
{       .mfb
        nop             0
        nop             0
#if 0
        br.sptk         epc_syscall_return
#endif
        ;;
}
END(lwp_trampoline)