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bfdb731438
If the specified needle crosses a page-boundary, the s390-z15 ifunc variant of
strstr truncates the needle which results in invalid results.
This is fixed by loading the needle beyond the page boundary to v18 instead of v16.
The bug is sometimes observable in test-strstr.c in check1 and check2 as the
haystack and needle is stored on stack. Thus the needle can be on a page boundary.
check2 is now extended to test haystack / needles located on stack, at end of page
and on two pages.
This bug was introduced with commit 6f47401bd5
("S390: Add arch13 strstr ifunc variant.") and is already released in glibc 2.30.
180 lines
5.9 KiB
ArmAsm
180 lines
5.9 KiB
ArmAsm
/* Vector optimized 32/64 bit S/390 version of strstr.
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Copyright (C) 2019 Free Software Foundation, Inc.
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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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#include <ifunc-strstr.h>
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#if HAVE_STRSTR_ARCH13
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# include "sysdep.h"
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# include "asm-syntax.h"
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.text
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/* char *strstr (const char *haystack=r2, const char *needle=r3)
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Locate a substring. */
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ENTRY(STRSTR_ARCH13)
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.machine "arch13"
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.machinemode "zarch_nohighgprs"
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lcbb %r1,0(%r3),6
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jo .Lneedle_on_bb /* Needle on block-boundary? */
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vl %v18,0(%r3),6 /* Load needle. */
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vfenezb %v19,%v18,%v18 /* v19[7] contains the length of needle. */
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.Lneedle_loaded:
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vlgvb %r4,%v19,7 /* Get index of zero or 16 if not found. */
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lghi %r5,17 /* See below: min-skip-partial-match-index. */
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cgibe %r4,0,0(%r14) /* Test if needle is zero and return. */
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/* The vstrs instruction is able to handle needles up to a length of 16,
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but then we may have to load the next part of haystack with a
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small offset. This will be slow - see examples:
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haystack =mmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmmmm...mmmmmmmmmmmmmmmmmmma
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needle = mmmmmmmmmmmmmma0
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=> needle_len=15; vstrs reports a partial match; haystack+=2
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haystack =mmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmmmm...mmmmmmmmmmmmmmmmmmma
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needle = mmmmmmmma0000000
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=> needle_len=9; vstrs reports a partial match; haystack+=8 */
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# if ! HAVE_STRSTR_Z13
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# error The arch13 variant of strstr needs the z13 variant of strstr!
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# endif
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clgfi %r4,9
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jh STRSTR_Z13
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/* In case of a partial match, the vstrs instruction returns the index
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of the partial match in a vector-register. Then we have to
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reload the string at the "current-position plus this index" and run
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vstrs again in order to determine if it was a full match or no match.
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Transferring this index from vr to gr, compute the haystack-address
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and loading with vl is quite slow as all instructions have data
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dependencies. Thus we assume, that a partial match is always at the
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first possible index and just load the next part of haystack from
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there instead of waiting until the correct index is computed:
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min-skip-partial-match-index = (16 - n_len) + 1 */
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sgr %r5,%r4
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.Lloop:
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lcbb %r1,0(%r2),6
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jo .Lloop_haystack_on_bb /* Haystack on block-boundary? */
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vl %v16,0(%r2) /* Load next part of haystack. */
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.Lloop_haystack_loaded:
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/* Vector string search with zero search (cc=0 => no match). */
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vstrs %v20,%v16,%v18,%v19,0,2
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jne .Lloop_vstrs_nonzero_cc
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lcbb %r1,16(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb16
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vl %v16,16(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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jne .Lloop_vstrs_nonzero_cc16
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lcbb %r1,32(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb32
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vl %v16,32(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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jne .Lloop_vstrs_nonzero_cc32
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lcbb %r1,48(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb48
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vl %v16,48(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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jne .Lloop_vstrs_nonzero_cc48
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la %r2,64(%r2)
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j .Lloop
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.Lloop_vstrs_nonzero_cc48:
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la %r2,16(%r2)
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.Lloop_vstrs_nonzero_cc32:
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la %r2,16(%r2)
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.Lloop_vstrs_nonzero_cc16:
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la %r2,16(%r2)
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.Lloop_vstrs_nonzero_cc:
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jh .Lend_match_found /* cc == 2 (full match) */
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jl .Lend_no_match /* cc == 1 (no match, end of string) */
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/* cc == 3 (partial match) See above: min-skip-partial-match-index! */
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lcbb %r1,0(%r5,%r2),6
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la %r2,0(%r5,%r2)
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jo .Lloop_haystack_on_bb
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vl %v16,0(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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.Lloop_vstrs_nonzero_cc_loop:
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jh .Lend_match_found
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jl .Lend_no_match
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la %r2,0(%r5,%r2)
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je .Lloop
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lcbb %r1,0(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb
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vl %v16,0(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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jh .Lend_match_found
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jl .Lend_no_match
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la %r2,0(%r5,%r2)
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je .Lloop
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lcbb %r1,0(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb
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vl %v16,0(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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jh .Lend_match_found
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jl .Lend_no_match
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la %r2,0(%r5,%r2)
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je .Lloop
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lcbb %r1,0(%r2),6 /* Next part of haystack. */
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jo .Lloop_haystack_on_bb
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vl %v16,0(%r2)
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vstrs %v20,%v16,%v18,%v19,0,2
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j .Lloop_vstrs_nonzero_cc_loop
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.Lend_no_match:
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lghi %r2,0
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br %r14
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.Lend_match_found:
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vlgvb %r4,%v20,7
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la %r2,0(%r4,%r2)
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br %r14
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.Lloop_haystack_on_bb48:
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la %r2,16(%r2)
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.Lloop_haystack_on_bb32:
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la %r2,16(%r2)
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.Lloop_haystack_on_bb16:
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la %r2,16(%r2)
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.Lloop_haystack_on_bb:
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/* Haystack located on page-boundary. */
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ahi %r1,-1 /* vll needs highest index instead of count. */
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vll %v16,%r1,0(%r2)
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vlvgb %v21,%r1,7
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vfenezb %v17,%v16,%v16 /* Search zero in loaded haystack bytes. */
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veclb %v17,%v21 /* Zero index <= loaded byte index? */
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jle .Lloop_haystack_loaded /* -> v16 contains full haystack. */
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vl %v16,0(%r2) /* Load haystack beyond page boundary. */
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j .Lloop_haystack_loaded
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.Lneedle_on_bb:
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/* Needle located on page-boundary. */
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ahi %r1,-1 /* vll needs highest index instead of count. */
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vll %v18,%r1,0(%r3)
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vlvgb %v21,%r1,7
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vfenezb %v19,%v18,%v18 /* Search zero in loaded needle bytes. */
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veclb %v19,%v21 /* Zero index <= max loaded byte index? */
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jle .Lneedle_loaded /* -> v18 contains full needle. */
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vl %v18,0(%r3) /* Load needle beyond page boundary. */
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vfenezb %v19,%v18,%v18
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j .Lneedle_loaded
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END(STRSTR_ARCH13)
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# if ! HAVE_STRSTR_IFUNC
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strong_alias (STRSTR_ARCH13, strstr)
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# endif
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# if STRSTR_Z13_ONLY_USED_AS_FALLBACK && defined SHARED && IS_IN (libc)
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strong_alias (STRSTR_ARCH13, __GI_strstr)
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# endif
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#endif
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