target/arm: Make sure that commpage's tb->size != 0

tb_gen_code() assumes that tb->size must never be zero, otherwise it
may produce spurious exceptions. For ARM this may happen when creating
a translation block for the commpage.

Fix by pretending that commpage translation blocks have at least one
instruction.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210416154939.32404-3-iii@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/target/arm/translate.c b/target/arm/translate.c
index 455352bcf6..8e0e55c1e0 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8981,6 +8981,7 @@ static void arm_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
     unsigned int insn;
 
     if (arm_pre_translate_insn(dc)) {
+        dc->base.pc_next += 4;
         return;
     }
 
@@ -9050,6 +9051,7 @@ static void thumb_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
     bool is_16bit;
 
     if (arm_pre_translate_insn(dc)) {
+        dc->base.pc_next += 2;
         return;
     }