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target/s390x: Fix the "ignored match" case in VSTRS 

Currently the emulation of VSTRS recognizes partial matches in presence
of \0 in the haystack, which, according to PoP, is not correct:

    If the ZS flag is one and a zero byte was detected
    in the second operand, then there can not be a
    partial match ...

Add a check for this. While at it, fold a number of explicitly handled
special cases into the generic logic.

Cc: qemu-stable@nongnu.org
Reported-by: Claudio Fontana <cfontana@suse.de>
Closes: https://lists.gnu.org/archive/html/qemu-devel/2023-08/msg00633.html
Fixes: 1d706f3141 ("target/s390x: vxeh2: vector string search")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230804233748.218935-3-iii@linux.ibm.com>
Tested-by: Claudio Fontana <cfontana@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 791b2b6a93)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Ilya Leoshkevich 2023-08-05 01:03:18 +02:00 committed by Michael Tokarev
parent 0434ea16fe
commit 08a4e6da12
1 changed files with 17 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
target/s390x/tcg/vec_string_helper.c
View File

@ -474,9 +474,9 @@ DEF_VSTRC_CC_RT_HELPER(32)
static int vstrs(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
const S390Vector *v4, uint8_t es, bool zs)
{
int substr_elen, substr_0, str_elen, i, j, k, cc;
int substr_elen, i, j, k, cc;
int nelem = 16 >> es;
bool eos = false;
int str_leftmost_0;
substr_elen = s390_vec_read_element8(v4, 7) >> es;
@ -498,47 +498,20 @@ static int vstrs(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
}
/* If ZS, look for eos in the searched string. */
str_leftmost_0 = nelem;
if (zs) {
for (k = 0; k < nelem; k++) {
if (s390_vec_read_element(v2, k, es) == 0) {
eos = true;
str_leftmost_0 = k;
break;
}
}
str_elen = k;
} else {
str_elen = nelem;
}
substr_0 = s390_vec_read_element(v3, 0, es);
for (k = 0; ; k++) {
for (; k < str_elen; k++) {
if (s390_vec_read_element(v2, k, es) == substr_0) {
break;
}
}
/* If we reached the end of the string, no match. */
if (k == str_elen) {
cc = eos; /* no match (with or without zero char) */
goto done;
}
/* If the substring is only one char, match. */
if (substr_elen == 1) {
cc = 2; /* full match */
goto done;
}
/* If the match begins at the last char, we have a partial match. */
if (k == str_elen - 1) {
cc = 3; /* partial match */
goto done;
}
cc = str_leftmost_0 == nelem ? 0 : 1; /* No match. */
for (k = 0; k < nelem; k++) {
i = MIN(nelem, k + substr_elen);
for (j = k + 1; j < i; j++) {
for (j = k; j < i; j++) {
uint32_t e2 = s390_vec_read_element(v2, j, es);
uint32_t e3 = s390_vec_read_element(v3, j - k, es);
if (e2 != e3) {
@ -546,9 +519,16 @@ static int vstrs(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
}
}
if (j == i) {
/* Matched up until "end". */
cc = i - k == substr_elen ? 2 : 3; /* full or partial match */
goto done;
/* All elements matched. */
if (k > str_leftmost_0) {
cc = 1; /* Ignored match. */
k = nelem;
} else if (i - k == substr_elen) {
cc = 2; /* Full match. */
} else {
cc = 3; /* Partial match. */
}
break;
}
}