363 lines
8.8 KiB
ArmAsm
363 lines
8.8 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* User Space Access Routines
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*
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* Copyright (C) 2000-2002 Hewlett-Packard (John Marvin)
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* Copyright (C) 2000 Richard Hirst <rhirst with parisc-linux.org>
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* Copyright (C) 2001 Matthieu Delahaye <delahaym at esiee.fr>
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* Copyright (C) 2003 Randolph Chung <tausq with parisc-linux.org>
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* Copyright (C) 2017 Helge Deller <deller@gmx.de>
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* Copyright (C) 2017 John David Anglin <dave.anglin@bell.net>
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*/
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/*
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* These routines still have plenty of room for optimization
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* (word & doubleword load/store, dual issue, store hints, etc.).
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*/
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/*
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* The following routines assume that space register 3 (sr3) contains
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* the space id associated with the current users address space.
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*/
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.text
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#include <asm/assembly.h>
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#include <asm/errno.h>
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#include <linux/linkage.h>
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/*
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* unsigned long lclear_user(void *to, unsigned long n)
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*
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* Returns 0 for success.
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* otherwise, returns number of bytes not transferred.
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*/
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ENTRY_CFI(lclear_user)
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comib,=,n 0,%r25,$lclu_done
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$lclu_loop:
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addib,<> -1,%r25,$lclu_loop
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1: stbs,ma %r0,1(%sr3,%r26)
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$lclu_done:
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bv %r0(%r2)
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copy %r25,%r28
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2: b $lclu_done
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ldo 1(%r25),%r25
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ASM_EXCEPTIONTABLE_ENTRY(1b,2b)
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ENDPROC_CFI(lclear_user)
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/*
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* unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
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*
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* Inputs:
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* - sr1 already contains space of source region
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* - sr2 already contains space of destination region
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*
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* Returns:
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* - number of bytes that could not be copied.
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* On success, this will be zero.
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*
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* This code is based on a C-implementation of a copy routine written by
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* Randolph Chung, which in turn was derived from the glibc.
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*
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* Several strategies are tried to try to get the best performance for various
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* conditions. In the optimal case, we copy by loops that copy 32- or 16-bytes
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* at a time using general registers. Unaligned copies are handled either by
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* aligning the destination and then using shift-and-write method, or in a few
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* cases by falling back to a byte-at-a-time copy.
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*
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* Testing with various alignments and buffer sizes shows that this code is
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* often >10x faster than a simple byte-at-a-time copy, even for strangely
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* aligned operands. It is interesting to note that the glibc version of memcpy
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* (written in C) is actually quite fast already. This routine is able to beat
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* it by 30-40% for aligned copies because of the loop unrolling, but in some
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* cases the glibc version is still slightly faster. This lends more
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* credibility that gcc can generate very good code as long as we are careful.
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*
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* Possible optimizations:
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* - add cache prefetching
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* - try not to use the post-increment address modifiers; they may create
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* additional interlocks. Assumption is that those were only efficient on old
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* machines (pre PA8000 processors)
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*/
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dst = arg0
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src = arg1
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len = arg2
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end = arg3
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t1 = r19
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t2 = r20
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t3 = r21
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t4 = r22
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srcspc = sr1
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dstspc = sr2
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t0 = r1
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a1 = t1
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a2 = t2
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a3 = t3
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a0 = t4
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save_src = ret0
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save_dst = ret1
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save_len = r31
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ENTRY_CFI(pa_memcpy)
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/* Last destination address */
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add dst,len,end
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/* short copy with less than 16 bytes? */
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cmpib,COND(>>=),n 15,len,.Lbyte_loop
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/* same alignment? */
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xor src,dst,t0
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extru t0,31,2,t1
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cmpib,<>,n 0,t1,.Lunaligned_copy
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#ifdef CONFIG_64BIT
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/* only do 64-bit copies if we can get aligned. */
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extru t0,31,3,t1
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cmpib,<>,n 0,t1,.Lalign_loop32
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/* loop until we are 64-bit aligned */
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.Lalign_loop64:
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extru dst,31,3,t1
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cmpib,=,n 0,t1,.Lcopy_loop_16_start
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20: ldb,ma 1(srcspc,src),t1
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21: stb,ma t1,1(dstspc,dst)
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b .Lalign_loop64
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ldo -1(len),len
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ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
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.Lcopy_loop_16_start:
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ldi 31,t0
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.Lcopy_loop_16:
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cmpb,COND(>>=),n t0,len,.Lword_loop
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10: ldd 0(srcspc,src),t1
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11: ldd 8(srcspc,src),t2
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ldo 16(src),src
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12: std,ma t1,8(dstspc,dst)
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13: std,ma t2,8(dstspc,dst)
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14: ldd 0(srcspc,src),t1
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15: ldd 8(srcspc,src),t2
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ldo 16(src),src
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16: std,ma t1,8(dstspc,dst)
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17: std,ma t2,8(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(11b,.Lcopy16_fault)
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ASM_EXCEPTIONTABLE_ENTRY(12b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(13b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(14b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(15b,.Lcopy16_fault)
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ASM_EXCEPTIONTABLE_ENTRY(16b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(17b,.Lcopy_done)
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b .Lcopy_loop_16
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ldo -32(len),len
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.Lword_loop:
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cmpib,COND(>>=),n 3,len,.Lbyte_loop
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20: ldw,ma 4(srcspc,src),t1
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21: stw,ma t1,4(dstspc,dst)
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b .Lword_loop
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ldo -4(len),len
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ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
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#endif /* CONFIG_64BIT */
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/* loop until we are 32-bit aligned */
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.Lalign_loop32:
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extru dst,31,2,t1
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cmpib,=,n 0,t1,.Lcopy_loop_8
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20: ldb,ma 1(srcspc,src),t1
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21: stb,ma t1,1(dstspc,dst)
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b .Lalign_loop32
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ldo -1(len),len
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ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
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.Lcopy_loop_8:
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cmpib,COND(>>=),n 15,len,.Lbyte_loop
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10: ldw 0(srcspc,src),t1
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11: ldw 4(srcspc,src),t2
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12: stw,ma t1,4(dstspc,dst)
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13: stw,ma t2,4(dstspc,dst)
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14: ldw 8(srcspc,src),t1
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15: ldw 12(srcspc,src),t2
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ldo 16(src),src
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16: stw,ma t1,4(dstspc,dst)
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17: stw,ma t2,4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(11b,.Lcopy8_fault)
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ASM_EXCEPTIONTABLE_ENTRY(12b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(13b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(14b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(15b,.Lcopy8_fault)
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ASM_EXCEPTIONTABLE_ENTRY(16b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(17b,.Lcopy_done)
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b .Lcopy_loop_8
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ldo -16(len),len
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.Lbyte_loop:
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cmpclr,COND(<>) len,%r0,%r0
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b,n .Lcopy_done
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20: ldb 0(srcspc,src),t1
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ldo 1(src),src
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21: stb,ma t1,1(dstspc,dst)
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b .Lbyte_loop
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ldo -1(len),len
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ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
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.Lcopy_done:
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bv %r0(%r2)
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sub end,dst,ret0
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/* src and dst are not aligned the same way. */
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/* need to go the hard way */
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.Lunaligned_copy:
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/* align until dst is 32bit-word-aligned */
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extru dst,31,2,t1
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cmpib,=,n 0,t1,.Lcopy_dstaligned
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20: ldb 0(srcspc,src),t1
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ldo 1(src),src
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21: stb,ma t1,1(dstspc,dst)
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b .Lunaligned_copy
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ldo -1(len),len
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ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
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ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
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.Lcopy_dstaligned:
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/* store src, dst and len in safe place */
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copy src,save_src
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copy dst,save_dst
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copy len,save_len
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/* len now needs give number of words to copy */
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SHRREG len,2,len
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/*
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* Copy from a not-aligned src to an aligned dst using shifts.
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* Handles 4 words per loop.
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*/
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depw,z src,28,2,t0
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subi 32,t0,t0
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mtsar t0
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extru len,31,2,t0
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cmpib,= 2,t0,.Lcase2
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/* Make src aligned by rounding it down. */
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depi 0,31,2,src
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cmpiclr,<> 3,t0,%r0
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b,n .Lcase3
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cmpiclr,<> 1,t0,%r0
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b,n .Lcase1
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.Lcase0:
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cmpb,COND(=) %r0,len,.Lcda_finish
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nop
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1: ldw,ma 4(srcspc,src), a3
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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1: ldw,ma 4(srcspc,src), a0
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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b,n .Ldo3
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.Lcase1:
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1: ldw,ma 4(srcspc,src), a2
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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1: ldw,ma 4(srcspc,src), a3
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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ldo -1(len),len
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cmpb,COND(=),n %r0,len,.Ldo0
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.Ldo4:
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1: ldw,ma 4(srcspc,src), a0
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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shrpw a2, a3, %sar, t0
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1: stw,ma t0, 4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
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.Ldo3:
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1: ldw,ma 4(srcspc,src), a1
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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shrpw a3, a0, %sar, t0
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1: stw,ma t0, 4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
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.Ldo2:
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1: ldw,ma 4(srcspc,src), a2
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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shrpw a0, a1, %sar, t0
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1: stw,ma t0, 4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
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.Ldo1:
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1: ldw,ma 4(srcspc,src), a3
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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shrpw a1, a2, %sar, t0
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1: stw,ma t0, 4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
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ldo -4(len),len
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cmpb,COND(<>) %r0,len,.Ldo4
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nop
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.Ldo0:
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shrpw a2, a3, %sar, t0
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1: stw,ma t0, 4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
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.Lcda_rdfault:
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.Lcda_finish:
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/* calculate new src, dst and len and jump to byte-copy loop */
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sub dst,save_dst,t0
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add save_src,t0,src
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b .Lbyte_loop
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sub save_len,t0,len
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.Lcase3:
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1: ldw,ma 4(srcspc,src), a0
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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1: ldw,ma 4(srcspc,src), a1
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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b .Ldo2
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ldo 1(len),len
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.Lcase2:
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1: ldw,ma 4(srcspc,src), a1
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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1: ldw,ma 4(srcspc,src), a2
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ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
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b .Ldo1
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ldo 2(len),len
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/* fault exception fixup handlers: */
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#ifdef CONFIG_64BIT
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.Lcopy16_fault:
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b .Lcopy_done
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10: std,ma t1,8(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
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#endif
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.Lcopy8_fault:
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b .Lcopy_done
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10: stw,ma t1,4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
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ENDPROC_CFI(pa_memcpy)
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.end
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