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/*
 * Itanium 2-optimized version of memcpy and copy_user function
 *
 * Inputs:
 *      in0:    destination address
 *      in1:    source address
 *      in2:    number of bytes to copy
 * Output:
 *      for bcopy:     return nothing
 *      for memcpy:    return dest
 *      for copy_user: 0 if success,
 *                     or number of bytes NOT copied if error occurred.
 *
 * Copyright (C) 2002 Intel Corp.
 * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
 */
#include <linux/config.h>
#include <asm/asmmacro.h>
#include <asm/page.h>

#if __GNUC__ >= 3
# define EK(y...)       EX(y)
#else
# define EK(y,x...)     x
#endif

/* McKinley specific optimization */

#define retval          r8
#define saved_pfs       r31
#define saved_lc        r10
#define saved_pr        r11
#define saved_in0       r14
#define saved_in1       r15
#define saved_in2       r16

#define src0            r2
#define src1            r3
#define dst0            r17
#define dst1            r18
#define cnt             r9

/* r19-r30 are temp for each code section */
#define PREFETCH_DIST   8
#define src_pre_mem     r19
#define dst_pre_mem     r20
#define src_pre_l2      r21
#define dst_pre_l2      r22
#define t1              r23
#define t2              r24
#define t3              r25
#define t4              r26
#define t5              t1      // alias!
#define t6              t2      // alias!
#define t7              t3      // alias!
#define n8              r27
#define t9              t5      // alias!
#define t10             t4      // alias!
#define t11             t7      // alias!
#define t12             t6      // alias!
#define t14             t10     // alias!
#define t13             r28
#define t15             r29
#define tmp             r30

/* defines for long_copy block */
#define A       0
#define B       (PREFETCH_DIST)
#define C       (B + PREFETCH_DIST)
#define D       (C + 1)
#define N       (D + 1)
#define Nrot    ((N + 7) & ~7)

/* alias */
#define in0             r32
#define in1             r33
#define in2             r34

GLOBAL_ENTRY(bcopy)
        .regstk 3,0,0,0
        mov r8=in0              // swap the src and dest arguments
        mov in0=in1
        ;;
        mov in1=r8
        ;;
END(bcopy)                      // fall through to memcpy
GLOBAL_ENTRY(memcpy)
        and     r28=0x7,in0
        and     r29=0x7,in1
        mov     f6=f0
        mov     retval=in0
        br.cond.sptk .common_code
        ;;
END(memcpy)
GLOBAL_ENTRY(__copy_user)
        .prologue
// check dest alignment
        and     r28=0x7,in0
        and     r29=0x7,in1
        mov     f6=f1
        mov     saved_in0=in0   // save dest pointer
        mov     saved_in1=in1   // save src pointer
        mov     retval=r0       // initialize return value
        ;;
.common_code:
        cmp.gt  p15,p0=8,in2    // check for small size
        cmp.ne  p13,p0=0,r28    // check dest alignment
        cmp.ne  p14,p0=0,r29    // check src alignment
        add     src0=0,in1
        sub     r30=8,r28       // for .align_dest
        mov     saved_in2=in2   // save len
        ;;
        add     dst0=0,in0
        add     dst1=1,in0      // dest odd index
        cmp.le  p6,p0 = 1,r30   // for .align_dest
(p15)   br.cond.dpnt .memcpy_short
(p13)   br.cond.dpnt .align_dest
(p14)   br.cond.dpnt .unaligned_src
        ;;

// both dest and src are aligned on 8-byte boundary
.aligned_src:
        .save ar.pfs, saved_pfs
        alloc   saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
        .save pr, saved_pr
        mov     saved_pr=pr

        shr.u   cnt=in2,7       // this much cache line
        ;;
        cmp.lt  p6,p0=2*PREFETCH_DIST,cnt
        cmp.lt  p7,p8=1,cnt
        .save ar.lc, saved_lc
        mov     saved_lc=ar.lc
        .body
        add     cnt=-1,cnt
        add     src_pre_mem=0,in1       // prefetch src pointer
        add     dst_pre_mem=0,in0       // prefetch dest pointer
        ;;
(p7)    mov     ar.lc=cnt       // prefetch count
(p8)    mov     ar.lc=r0
(p6)    br.cond.dpnt .long_copy
        ;;

.prefetch:
        lfetch    [src_pre_mem], 128
        lfetch.excl [dst_pre_mem], 128
        br.cloop.dptk.few .prefetch
        ;;

.medium_copy:
        and     tmp=31,in2      // copy length after iteration
        shr.u   r29=in2,5       // number of 32-byte iteration
        add     dst1=8,dst0     // 2nd dest pointer
        ;;
        add     cnt=-1,r29      // ctop iteration adjustment
        cmp.eq  p10,p0=r29,r0   // do we really need to loop?
        add     src1=8,src0     // 2nd src pointer
        cmp.le  p6,p0=8,tmp
        ;;
        cmp.le  p7,p0=16,tmp
        mov     ar.lc=cnt       // loop setup
        cmp.eq  p16,p17 = r0,r0
        mov     ar.ec=2
(p10)   br.dpnt.few .aligned_src_tail
        ;;
//      .align 32
1:
EX(.ex_handler, (p16)   ld8     r34=[src0],16)
EK(.ex_handler, (p16)   ld8     r38=[src1],16)
EX(.ex_handler, (p17)   st8     [dst0]=r33,16)
EK(.ex_handler, (p17)   st8     [dst1]=r37,16)
        ;;
EX(.ex_handler, (p16)   ld8     r32=[src0],16)
EK(.ex_handler, (p16)   ld8     r36=[src1],16)
EX(.ex_handler, (p16)   st8     [dst0]=r34,16)
EK(.ex_handler, (p16)   st8     [dst1]=r38,16)
        br.ctop.dptk.few 1b
        ;;

.aligned_src_tail:
EX(.ex_handler, (p6)    ld8     t1=[src0])
        mov     ar.lc=saved_lc
        mov     ar.pfs=saved_pfs
EX(.ex_hndlr_s, (p7)    ld8     t2=[src1],8)
        cmp.le  p8,p0=24,tmp
        and     r21=-8,tmp
        ;;
EX(.ex_hndlr_s, (p8)    ld8     t3=[src1])
EX(.ex_handler, (p6)    st8     [dst0]=t1)      // store byte 1
        and     in2=7,tmp       // remaining length
EX(.ex_hndlr_d, (p7)    st8     [dst1]=t2,8)    // store byte 2
        add     src0=src0,r21   // setting up src pointer
        add     dst0=dst0,r21   // setting up dest pointer
        ;;
EX(.ex_handler, (p8)    st8     [dst1]=t3)      // store byte 3
        mov     pr=saved_pr,-1
        br.dptk.many .memcpy_short
        ;;

/* code taken from copy_page_mck */
.long_copy:
        .rotr v[2*PREFETCH_DIST]
        .rotp p[N]

        mov src_pre_mem = src0
        mov pr.rot = 0x10000
        mov ar.ec = 1                           // special unrolled loop

        mov dst_pre_mem = dst0

        add src_pre_l2 = 8*8, src0
        add dst_pre_l2 = 8*8, dst0
        ;;
        add src0 = 8, src_pre_mem               // first t1 src
        mov ar.lc = 2*PREFETCH_DIST - 1
        shr.u cnt=in2,7                         // number of lines
        add src1 = 3*8, src_pre_mem             // first t3 src
        add dst0 = 8, dst_pre_mem               // first t1 dst
        add dst1 = 3*8, dst_pre_mem             // first t3 dst
        ;;
        and tmp=127,in2                         // remaining bytes after this block
        add cnt = -(2*PREFETCH_DIST) - 1, cnt
        // same as .line_copy loop, but with all predicated-off instructions removed:
.prefetch_loop:
EX(.ex_hndlr_lcpy_1, (p[A])     ld8 v[A] = [src_pre_mem], 128)          // M0
EK(.ex_hndlr_lcpy_1, (p[B])     st8 [dst_pre_mem] = v[B], 128)          // M2
        br.ctop.sptk .prefetch_loop
        ;;
        cmp.eq p16, p0 = r0, r0                 // reset p16 to 1
        mov ar.lc = cnt
        mov ar.ec = N                           // # of stages in pipeline
        ;;
.line_copy:
EX(.ex_handler, (p[D])  ld8 t2 = [src0], 3*8)                   // M0
EK(.ex_handler, (p[D])  ld8 t4 = [src1], 3*8)                   // M1
EX(.ex_handler_lcpy,    (p[B])  st8 [dst_pre_mem] = v[B], 128)          // M2 prefetch dst from memory
EK(.ex_handler_lcpy,    (p[D])  st8 [dst_pre_l2] = n8, 128)             // M3 prefetch dst from L2
        ;;
EX(.ex_handler_lcpy,    (p[A])  ld8 v[A] = [src_pre_mem], 128)          // M0 prefetch src from memory
EK(.ex_handler_lcpy,    (p[C])  ld8 n8 = [src_pre_l2], 128)             // M1 prefetch src from L2
EX(.ex_handler, (p[D])  st8 [dst0] =  t1, 8)                    // M2
EK(.ex_handler, (p[D])  st8 [dst1] =  t3, 8)                    // M3
        ;;
EX(.ex_handler, (p[D])  ld8  t5 = [src0], 8)
EK(.ex_handler, (p[D])  ld8  t7 = [src1], 3*8)
EX(.ex_handler, (p[D])  st8 [dst0] =  t2, 3*8)
EK(.ex_handler, (p[D])  st8 [dst1] =  t4, 3*8)
        ;;
EX(.ex_handler, (p[D])  ld8  t6 = [src0], 3*8)
EK(.ex_handler, (p[D])  ld8 t10 = [src1], 8)
EX(.ex_handler, (p[D])  st8 [dst0] =  t5, 8)
EK(.ex_handler, (p[D])  st8 [dst1] =  t7, 3*8)
        ;;
EX(.ex_handler, (p[D])  ld8  t9 = [src0], 3*8)
EK(.ex_handler, (p[D])  ld8 t11 = [src1], 3*8)
EX(.ex_handler, (p[D])  st8 [dst0] =  t6, 3*8)
EK(.ex_handler, (p[D])  st8 [dst1] = t10, 8)
        ;;
EX(.ex_handler, (p[D])  ld8 t12 = [src0], 8)
EK(.ex_handler, (p[D])  ld8 t14 = [src1], 8)
EX(.ex_handler, (p[D])  st8 [dst0] =  t9, 3*8)
EK(.ex_handler, (p[D])  st8 [dst1] = t11, 3*8)
        ;;
EX(.ex_handler, (p[D])  ld8 t13 = [src0], 4*8)
EK(.ex_handler, (p[D])  ld8 t15 = [src1], 4*8)
EX(.ex_handler, (p[D])  st8 [dst0] = t12, 8)
EK(.ex_handler, (p[D])  st8 [dst1] = t14, 8)
        ;;
EX(.ex_handler, (p[C])  ld8  t1 = [src0], 8)
EK(.ex_handler, (p[C])  ld8  t3 = [src1], 8)
EX(.ex_handler, (p[D])  st8 [dst0] = t13, 4*8)
EK(.ex_handler, (p[D])  st8 [dst1] = t15, 4*8)
        br.ctop.sptk .line_copy
        ;;

        add dst0=-8,dst0
        add src0=-8,src0
        mov in2=tmp
        .restore sp
        br.sptk.many .medium_copy
        ;;

#define BLOCK_SIZE      128*32
#define blocksize       r23
#define curlen          r24

// dest is on 8-byte boundary, src is not. We need to do
// ld8-ld8, shrp, then st8.  Max 8 byte copy per cycle.
.unaligned_src:
        .prologue
        .save ar.pfs, saved_pfs
        alloc   saved_pfs=ar.pfs,3,5,0,8
        .save ar.lc, saved_lc
        mov     saved_lc=ar.lc
        .save pr, saved_pr
        mov     saved_pr=pr
        .body
.4k_block:
        mov     saved_in0=dst0  // need to save all input arguments
        mov     saved_in2=in2
        mov     blocksize=BLOCK_SIZE
        ;;
        cmp.lt  p6,p7=blocksize,in2
        mov     saved_in1=src0
        ;;
(p6)    mov     in2=blocksize
        ;;
        shr.u   r21=in2,7       // this much cache line
        shr.u   r22=in2,4       // number of 16-byte iteration
        and     curlen=15,in2   // copy length after iteration
        and     r30=7,src0      // source alignment
        ;;
        cmp.lt  p7,p8=1,r21
        add     cnt=-1,r21
        ;;

        add     src_pre_mem=0,src0      // prefetch src pointer
        add     dst_pre_mem=0,dst0      // prefetch dest pointer
        and     src0=-8,src0            // 1st src pointer
(p7)    mov     ar.lc = r21
(p8)    mov     ar.lc = r0
        ;;
//      .align 32
1:      lfetch    [src_pre_mem], 128
        lfetch.excl [dst_pre_mem], 128
        br.cloop.dptk.few 1b
        ;;

        shladd  dst1=r22,3,dst0 // 2nd dest pointer
        shladd  src1=r22,3,src0 // 2nd src pointer
        cmp.eq  p8,p9=r22,r0    // do we really need to loop?
        cmp.le  p6,p7=8,curlen; // have at least 8 byte remaining?
        add     cnt=-1,r22      // ctop iteration adjustment
        ;;
EX(.ex_handler, (p9)    ld8     r33=[src0],8)   // loop primer
EK(.ex_handler, (p9)    ld8     r37=[src1],8)
(p8)    br.dpnt.few .noloop
        ;;

// The jump address is calculated based on src alignment. The COPYU
// macro below need to confine its size to power of two, so an entry
// can be caulated using shl instead of an expensive multiply. The
// size is then hard coded by the following #define to match the
// actual size.  This make it somewhat tedious when COPYU macro gets
// changed and this need to be adjusted to match.
#define LOOP_SIZE 6
1:
        mov     r29=ip          // jmp_table thread
        mov     ar.lc=cnt
        ;;
        add     r29=.jump_table - 1b - (.jmp1-.jump_table), r29
        shl     r28=r30, LOOP_SIZE      // jmp_table thread
        mov     ar.ec=2         // loop setup
        ;;
        add     r29=r29,r28             // jmp_table thread
        cmp.eq  p16,p17=r0,r0
        ;;
        mov     b6=r29                  // jmp_table thread
        ;;
        br.cond.sptk.few b6

// for 8-15 byte case
// We will skip the loop, but need to replicate the side effect
// that the loop produces.
.noloop:
EX(.ex_handler, (p6)    ld8     r37=[src1],8)
        add     src0=8,src0
(p6)    shl     r25=r30,3
        ;;
EX(.ex_handler, (p6)    ld8     r27=[src1])
(p6)    shr.u   r28=r37,r25
(p6)    sub     r26=64,r25
        ;;
(p6)    shl     r27=r27,r26
        ;;
(p6)    or      r21=r28,r27

.unaligned_src_tail:
/* check if we have more than blocksize to copy, if so go back */
        cmp.gt  p8,p0=saved_in2,blocksize
        ;;
(p8)    add     dst0=saved_in0,blocksize
(p8)    add     src0=saved_in1,blocksize
(p8)    sub     in2=saved_in2,blocksize
(p8)    br.dpnt .4k_block
        ;;

/* we have up to 15 byte to copy in the tail.
 * part of work is already done in the jump table code
 * we are at the following state.
 * src side:
 * 
 *   xxxxxx xx                   <----- r21 has xxxxxxxx already
 * -------- -------- --------
 * 0        8        16
 *          ^
 *          |
 *          src1
 * 
 * dst
 * -------- -------- --------
 * ^
 * |
 * dst1
 */
EX(.ex_handler, (p6)    st8     [dst1]=r21,8)   // more than 8 byte to copy
(p6)    add     curlen=-8,curlen        // update length
        mov     ar.pfs=saved_pfs
        ;;
        mov     ar.lc=saved_lc
        mov     pr=saved_pr,-1
        mov     in2=curlen      // remaining length
        mov     dst0=dst1       // dest pointer
        add     src0=src1,r30   // forward by src alignment
        ;;

// 7 byte or smaller.
.memcpy_short:
        cmp.le  p8,p9   = 1,in2
        cmp.le  p10,p11 = 2,in2
        cmp.le  p12,p13 = 3,in2
        cmp.le  p14,p15 = 4,in2
        add     src1=1,src0     // second src pointer
        add     dst1=1,dst0     // second dest pointer
        ;;

EX(.ex_handler_short, (p8)      ld1     t1=[src0],2)
EK(.ex_handler_short, (p10)     ld1     t2=[src1],2)
(p9)    br.ret.dpnt rp          // 0 byte copy
        ;;

EX(.ex_handler_short, (p8)      st1     [dst0]=t1,2)
EK(.ex_handler_short, (p10)     st1     [dst1]=t2,2)
(p11)   br.ret.dpnt rp          // 1 byte copy

EX(.ex_handler_short, (p12)     ld1     t3=[src0],2)
EK(.ex_handler_short, (p14)     ld1     t4=[src1],2)
(p13)   br.ret.dpnt rp          // 2 byte copy
        ;;

        cmp.le  p6,p7   = 5,in2
        cmp.le  p8,p9   = 6,in2
        cmp.le  p10,p11 = 7,in2

EX(.ex_handler_short, (p12)     st1     [dst0]=t3,2)
EK(.ex_handler_short, (p14)     st1     [dst1]=t4,2)
(p15)   br.ret.dpnt rp          // 3 byte copy
        ;;

EX(.ex_handler_short, (p6)      ld1     t5=[src0],2)
EK(.ex_handler_short, (p8)      ld1     t6=[src1],2)
(p7)    br.ret.dpnt rp          // 4 byte copy
        ;;

EX(.ex_handler_short, (p6)      st1     [dst0]=t5,2)
EK(.ex_handler_short, (p8)      st1     [dst1]=t6,2)
(p9)    br.ret.dptk rp          // 5 byte copy

EX(.ex_handler_short, (p10)     ld1     t7=[src0],2)
(p11)   br.ret.dptk rp          // 6 byte copy
        ;;

EX(.ex_handler_short, (p10)     st1     [dst0]=t7,2)
        br.ret.dptk rp          // done all cases


/* Align dest to nearest 8-byte boundary. We know we have at
 * least 7 bytes to copy, enough to crawl to 8-byte boundary.
 * Actual number of byte to crawl depend on the dest alignment.
 * 7 byte or less is taken care at .memcpy_short

 * src0 - source even index
 * src1 - source  odd index
 * dst0 - dest even index
 * dst1 - dest  odd index
 * r30  - distance to 8-byte boundary
 */

.align_dest:
        add     src1=1,in1      // source odd index
        cmp.le  p7,p0 = 2,r30   // for .align_dest
        cmp.le  p8,p0 = 3,r30   // for .align_dest
EX(.ex_handler_short, (p6)      ld1     t1=[src0],2)
        cmp.le  p9,p0 = 4,r30   // for .align_dest
        cmp.le  p10,p0 = 5,r30
        ;;
EX(.ex_handler_short, (p7)      ld1     t2=[src1],2)
EK(.ex_handler_short, (p8)      ld1     t3=[src0],2)
        cmp.le  p11,p0 = 6,r30
EX(.ex_handler_short, (p6)      st1     [dst0] = t1,2)
        cmp.le  p12,p0 = 7,r30
        ;;
EX(.ex_handler_short, (p9)      ld1     t4=[src1],2)
EK(.ex_handler_short, (p10)     ld1     t5=[src0],2)
EX(.ex_handler_short, (p7)      st1     [dst1] = t2,2)
EK(.ex_handler_short, (p8)      st1     [dst0] = t3,2)
        ;;
EX(.ex_handler_short, (p11)     ld1     t6=[src1],2)
EK(.ex_handler_short, (p12)     ld1     t7=[src0],2)
        cmp.eq  p6,p7=r28,r29
EX(.ex_handler_short, (p9)      st1     [dst1] = t4,2)
EK(.ex_handler_short, (p10)     st1     [dst0] = t5,2)
        sub     in2=in2,r30
        ;;
EX(.ex_handler_short, (p11)     st1     [dst1] = t6,2)
EK(.ex_handler_short, (p12)     st1     [dst0] = t7)
        add     dst0=in0,r30    // setup arguments
        add     src0=in1,r30
(p6)    br.cond.dptk .aligned_src
(p7)    br.cond.dpnt .unaligned_src
        ;;

/* main loop body in jump table format */
#define COPYU(shift)                                                                    \
1:                                                                                      \
EX(.ex_handler,  (p16)  ld8     r32=[src0],8);          /* 1 */                         \
EK(.ex_handler,  (p16)  ld8     r36=[src1],8);                                          \
                 (p17)  shrp    r35=r33,r34,shift;;     /* 1 */                         \
EX(.ex_handler,  (p6)   ld8     r22=[src1]);    /* common, prime for tail section */    \
                 nop.m  0;                                                              \
                 (p16)  shrp    r38=r36,r37,shift;                                      \
EX(.ex_handler,  (p17)  st8     [dst0]=r35,8);          /* 1 */                         \
EK(.ex_handler,  (p17)  st8     [dst1]=r39,8);                                          \
                 br.ctop.dptk.few 1b;;                                                  \
                 (p7)   add     src1=-8,src1;   /* back out for <8 byte case */         \
                 shrp   r21=r22,r38,shift;      /* speculative work */                  \
                 br.sptk.few .unaligned_src_tail /* branch out of jump table */         \
                 ;;
//      .align 32
.jump_table:
        COPYU(8)        // unaligned cases
.jmp1:
        COPYU(16)
        COPYU(24)
        COPYU(32)
        COPYU(40)
        COPYU(48)
        COPYU(56)

#undef A
#undef B
#undef C
#undef D
END(memcpy)

/*
 * Due to lack of local tag support in gcc 2.x assembler, it is not clear which
 * instruction failed in the bundle.  The exception algorithm is that we
 * first figure out the faulting address, then detect if there is any
 * progress made on the copy, if so, redo the copy from last known copied
 * location up to the faulting address (exclusive). In the copy_from_user
 * case, remaining byte in kernel buffer will be zeroed.
 *
 * Take copy_from_user as an example, in the code there are multiple loads
 * in a bundle and those multiple loads could span over two pages, the
 * faulting address is calculated as page_round_down(max(src0, src1)).
 * This is based on knowledge that if we can access one byte in a page, we
 * can access any byte in that page.
 *
 * predicate used in the exception handler:
 * p6-p7: direction
 * p10-p11: src faulting addr calculation
 * p12-p13: dst faulting addr calculation
 */

#define A       r19
#define B       r20
#define C       r21
#define D       r22
#define F       r28

#define memset_arg0     r32
#define memset_arg2     r33

#define saved_retval    loc0
#define saved_rtlink    loc1
#define saved_pfs_stack loc2

.ex_hndlr_s:
        add     src0=8,src0
        br.sptk .ex_handler
        ;;
.ex_hndlr_d:
        add     dst0=8,dst0
        br.sptk .ex_handler
        ;;
.ex_hndlr_lcpy_1:
        mov     src1=src_pre_mem
        mov     dst1=dst_pre_mem
        cmp.gtu p10,p11=src_pre_mem,saved_in1
        cmp.gtu p12,p13=dst_pre_mem,saved_in0
        ;;
(p10)   add     src0=8,saved_in1
(p11)   mov     src0=saved_in1
(p12)   add     dst0=8,saved_in0
(p13)   mov     dst0=saved_in0
        br.sptk .ex_handler
.ex_handler_lcpy:
        // in line_copy block, the preload addresses should always ahead
        // of the other two src/dst pointers.  Furthermore, src1/dst1 should
        // always ahead of src0/dst0.
        mov     src1=src_pre_mem
        mov     dst1=dst_pre_mem
.ex_handler:
        mov     pr=saved_pr,-1          // first restore pr, lc, and pfs
        mov     ar.lc=saved_lc
        mov     ar.pfs=saved_pfs
        ;;
.ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs
        cmp.ltu p6,p7=saved_in0, saved_in1      // get the copy direction
        cmp.ltu p10,p11=src0,src1
        cmp.ltu p12,p13=dst0,dst1
        fcmp.eq p8,p0=f6,f0             // is it memcpy?
        mov     tmp = dst0
        ;;
(p11)   mov     src1 = src0             // pick the larger of the two
(p13)   mov     dst0 = dst1             // make dst0 the smaller one
(p13)   mov     dst1 = tmp              // and dst1 the larger one
        ;;
(p6)    dep     F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary
(p7)    dep     F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary
        ;;
(p6)    cmp.le  p14,p0=dst0,saved_in0   // no progress has been made on store
(p7)    cmp.le  p14,p0=src0,saved_in1   // no progress has been made on load
        mov     retval=saved_in2
(p8)    ld1     tmp=[src1]              // force an oops for memcpy call
(p8)    st1     [dst1]=r0               // force an oops for memcpy call
(p14)   br.ret.sptk.many rp

/*
 * The remaining byte to copy is calculated as:
 *
 * A =  (faulting_addr - orig_src)      -> len to faulting ld address
 *      or 
 *      (faulting_addr - orig_dst)      -> len to faulting st address
 * B =  (cur_dst - orig_dst)            -> len copied so far
 * C =  A - B                           -> len need to be copied
 * D =  orig_len - A                    -> len need to be zeroed
 */
(p6)    sub     A = F, saved_in0
(p7)    sub     A = F, saved_in1
        clrrrb
        ;;
        alloc   saved_pfs_stack=ar.pfs,3,3,3,0
        sub     B = dst0, saved_in0     // how many byte copied so far
        ;;
        sub     C = A, B
        sub     D = saved_in2, A
        ;;
        cmp.gt  p8,p0=C,r0              // more than 1 byte?
        add     memset_arg0=saved_in0, A
(p6)    mov     memset_arg2=0           // copy_to_user should not call memset
(p7)    mov     memset_arg2=D           // copy_from_user need to have kbuf zeroed
        mov     r8=0
        mov     saved_retval = D
        mov     saved_rtlink = b0

        add     out0=saved_in0, B
        add     out1=saved_in1, B
        mov     out2=C
(p8)    br.call.sptk.few b0=__copy_user // recursive call
        ;;

        add     saved_retval=saved_retval,r8    // above might return non-zero value
        cmp.gt  p8,p0=memset_arg2,r0    // more than 1 byte?
        mov     out0=memset_arg0        // *s
        mov     out1=r0                 // c
        mov     out2=memset_arg2        // n
(p8)    br.call.sptk.few b0=memset
        ;;

        mov     retval=saved_retval
        mov     ar.pfs=saved_pfs_stack
        mov     b0=saved_rtlink
        br.ret.sptk.many rp

/* end of McKinley specific optimization */
END(__copy_user)