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[PULL,09/18] target/arm/translate-neon: UNDEF if VLD1/VST1 stride bits are non-zero

Message ID 20220307164709.2503250-10-peter.maydell@linaro.org
State Accepted
Commit c64ee036ac215f970a76e8c51cb1cfaaef70feb5
Headers show
Series [PULL,01/18] util: Make qemu_oom_check() a static function | expand

Commit Message

Peter Maydell March 7, 2022, 4:47 p.m. UTC 
For VLD1/VST1 (single element to one lane) we are only accessing one
register, and so the 'stride' is meaningless.  The bits that would
specify stride (insn bit [4] for size=1, bit [6] for size=2) are
specified to be zero in the encoding (which would correspond to a
stride of 1 for VLD2/VLD3/VLD4 etc), and we must UNDEF if they are
not.

We failed to make this check, which meant that we would incorrectly
handle some instruction patterns as loads or stores instead of
UNDEFing them. Enforce that stride == 1 for the nregs == 1 case.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/890
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220303113741.2156877-2-peter.maydell@linaro.org
---
 target/arm/translate-neon.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/target/arm/translate-neon.c b/target/arm/translate-neon.c
index 3854dd35163..072fdc1e6ee 100644
--- a/target/arm/translate-neon.c
+++ b/target/arm/translate-neon.c
@@ -657,6 +657,9 @@  static bool trans_VLDST_single(DisasContext *s, arg_VLDST_single *a)
     /* Catch the UNDEF cases. This is unavoidably a bit messy. */
     switch (nregs) {
     case 1:
+        if (a->stride != 1) {
+            return false;
+        }
         if (((a->align & (1 << a->size)) != 0) ||
             (a->size == 2 && (a->align == 1 || a->align == 2))) {
             return false;