[Qemu-devel] [PATCH v2 28/68] target/arm: Diagnose writeback register in list for LDM for v7

[Richard Henderson]

Prior to v7, for the A32 encoding, this operation wrote an UNKNOWN
value back to the base register.  Starting in v7 this is UNPREDICTABLE.

Signed-off-by: Richard Henderson <address@hidden>
---
 target/arm/translate.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index 4451adbb97..29e2eae441 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -9880,6 +9880,14 @@ static bool do_ldm(DisasContext *s, arg_ldst_block *a)
 
 static bool trans_LDM_a32(DisasContext *s, arg_ldst_block *a)
 {
+    /*
+     * Writeback register in register list is UNPREDICATABLE
+     * for ArchVersion() >= 7.  Prior to v7, A32 would write
+     * an UNKNOWN value to the base register.
+     */
+    if (ENABLE_ARCH_7 && a->w && (a->list & (1 << a->rn))) {
+        return false;
+    }
     return do_ldm(s, a);
 }
 
-- 
2.17.1