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7c45df18e1
On s390 (31bit), the pointer to the first byte after s always wraps around with n >= 0x80000000 and can lead to stop searching before end of s. Thus this patch just use NULL as byte after s in this case and the srst instruction stops searching with "not found" when wrapping around from top address to zero. This is observable with testcase string/test-memchr starting with commit "String: Add overflow tests for strnlen, memchr, and strncat [BZ #27974]" https://sourceware.org/git/?p=glibc.git;a=commit;h=da5a6fba0febbfc90896ce1b2eb75c6d8a88a72d
77 lines
2.2 KiB
ArmAsm
77 lines
2.2 KiB
ArmAsm
/* Search a character in a block of memory. 31/64 bit S/390 version.
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Copyright (C) 2001-2021 Free Software Foundation, Inc.
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Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* INPUT PARAMETERS
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%r2 = address to memory area
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%r3 = character to find
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%r4 = number of bytes to search. */
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#include <ifunc-memchr.h>
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#include "sysdep.h"
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#include "asm-syntax.h"
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#if HAVE_MEMCHR_Z900_G5
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# if defined __s390x__
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# define SLGR slgr
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# define LGHI lghi
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# define NGR ngr
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# define LGR lgr
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# else
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# define SLGR slr
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# define LGHI lhi
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# define NGR nr
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# define LGR lr
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# endif /* ! defined __s390x__ */
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.text
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ENTRY(MEMCHR_Z900_G5)
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LGHI %r0,0xff
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NGR %r0,%r3
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LGR %r1,%r2
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# if ! defined __s390x__
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tmlh %r4,32768
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jo 3f /* Jump away if n >= 0x80000000 */
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# endif
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la %r2,0(%r4,%r1)
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0: srst %r2,%r1
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jo 0b
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brc 13,1f
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SLGR %r2,%r2
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1: br %r14
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# if ! defined __s390x__
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/* On s390 (31bit), the pointer to the first byte after s (stored in
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r2) always wraps around with n >= 0x80000000 and can lead to stop
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searching before end of s. Thus just use r2=0 in this case.
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If r2 < r1, the srst instruction stops searching with cc=2 "not
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found" when wrapping around from top address to zero. */
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3: SLGR %r2,%r2
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j 0b
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# endif
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END(MEMCHR_Z900_G5)
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# if ! HAVE_MEMCHR_IFUNC
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strong_alias (MEMCHR_Z900_G5, __memchr)
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weak_alias (__memchr, memchr)
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# endif
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# if defined SHARED && IS_IN (libc)
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strong_alias (MEMCHR_Z900_G5, __GI_memchr)
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# endif
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#endif
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