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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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554bfeceb8
pa_memcpy() is the major memcpy implementation in the parisc kernel which is used to do any kind of userspace/kernel memory copies. Al Viro noticed various bugs in the implementation of pa_mempcy(), most notably that in case of faults it may report back to have copied more bytes than it actually did. Fixing those bugs is quite hard in the C-implementation, because the compiler is messing around with the registers and we are not guaranteed that specific variables are always in the same processor registers. This makes proper fault handling complicated. This patch implements pa_memcpy() in assembler. That way we have correct fault handling and adding a 64-bit copy routine was quite easy. Runtime tested with 32- and 64bit kernels. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Cc: <stable@vger.kernel.org> # v4.9+ Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
454 lines
11 KiB
ArmAsm
454 lines
11 KiB
ArmAsm
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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* get_sr gets the appropriate space value into
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* sr1 for kernel/user space access, depending
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* on the flag stored in the task structure.
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*/
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.macro get_sr
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mfctl %cr30,%r1
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ldw TI_SEGMENT(%r1),%r22
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mfsp %sr3,%r1
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or,<> %r22,%r0,%r0
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copy %r0,%r1
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mtsp %r1,%sr1
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.endm
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.macro fixup_branch lbl
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ldil L%\lbl, %r1
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ldo R%\lbl(%r1), %r1
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bv %r0(%r1)
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.endm
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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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.proc
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.callinfo NO_CALLS
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.entry
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comib,=,n 0,%r25,$lclu_done
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get_sr
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$lclu_loop:
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addib,<> -1,%r25,$lclu_loop
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1: stbs,ma %r0,1(%sr1,%r26)
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$lclu_done:
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bv %r0(%r2)
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copy %r25,%r28
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.exit
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ENDPROC_CFI(lclear_user)
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.section .fixup,"ax"
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2: fixup_branch $lclu_done
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ldo 1(%r25),%r25
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.previous
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ASM_EXCEPTIONTABLE_ENTRY(1b,2b)
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.procend
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/*
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* long lstrnlen_user(char *s, long n)
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*
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* Returns 0 if exception before zero byte or reaching N,
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* N+1 if N would be exceeded,
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* else strlen + 1 (i.e. includes zero byte).
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*/
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ENTRY_CFI(lstrnlen_user)
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.proc
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.callinfo NO_CALLS
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.entry
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comib,= 0,%r25,$lslen_nzero
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copy %r26,%r24
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get_sr
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1: ldbs,ma 1(%sr1,%r26),%r1
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$lslen_loop:
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comib,=,n 0,%r1,$lslen_done
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addib,<> -1,%r25,$lslen_loop
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2: ldbs,ma 1(%sr1,%r26),%r1
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$lslen_done:
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bv %r0(%r2)
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sub %r26,%r24,%r28
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.exit
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$lslen_nzero:
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b $lslen_done
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ldo 1(%r26),%r26 /* special case for N == 0 */
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ENDPROC_CFI(lstrnlen_user)
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.section .fixup,"ax"
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3: fixup_branch $lslen_done
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copy %r24,%r26 /* reset r26 so 0 is returned on fault */
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.previous
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ASM_EXCEPTIONTABLE_ENTRY(1b,3b)
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ASM_EXCEPTIONTABLE_ENTRY(2b,3b)
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.procend
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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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.proc
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.callinfo NO_CALLS
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.entry
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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,>>=,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
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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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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_4
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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_4:
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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_4
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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,COND(=),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,= %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,=,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,<> %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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10: b .Lcopy_done
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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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10: b .Lcopy_done
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stw,ma t1,4(dstspc,dst)
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ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
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.exit
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ENDPROC_CFI(pa_memcpy)
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.procend
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.end
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