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authorIlya Leoshkevich <iii@linux.ibm.com>2022-01-12 17:50:14 +0100
committerThomas Huth <thuth@redhat.com>2022-01-17 08:36:33 +0100
commitdf103c09bc2f549d36ba6313a69c18fc003ef1ee (patch)
tree2df4706ba21bf1d8b7117a62be6d1c7e1aad30ef
parent57556b28afde4b039bb12bfc274bd8df9022d946 (diff)
downloadfocaccia-qemu-df103c09bc2f549d36ba6313a69c18fc003ef1ee.tar.gz
focaccia-qemu-df103c09bc2f549d36ba6313a69c18fc003ef1ee.zip
target/s390x: Fix cc_calc_sla_64() missing overflows
An overflow occurs for SLAG when at least one shifted bit is not equal
to sign bit. Therefore, we need to check that `shift + 1` bits are
neither all 0s nor all 1s. The current code checks only `shift` bits,
missing some overflows.

Fixes: cbe24bfa91d2 ("target-s390: Convert SHIFT, ROTATE SINGLE")
Co-developed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20220112165016.226996-4-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Diffstat (limited to '')
-rw-r--r--target/s390x/tcg/cc_helper.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/target/s390x/tcg/cc_helper.c b/target/s390x/tcg/cc_helper.c
index c2c96c3a3c..c9b7b0e8c6 100644
--- a/target/s390x/tcg/cc_helper.c
+++ b/target/s390x/tcg/cc_helper.c
@@ -297,7 +297,7 @@ static uint32_t cc_calc_sla_32(uint32_t src, int shift)
 
 static uint32_t cc_calc_sla_64(uint64_t src, int shift)
 {
-    uint64_t mask = ((1ULL << shift) - 1ULL) << (64 - shift);
+    uint64_t mask = -1ULL << (63 - shift);
     uint64_t sign = 1ULL << 63;
     uint64_t match;
     int64_t r;