target/i386: fix size of EBP writeback in gen_enter()

The calculation of FrameTemp is done using the size indicated by mo_pushpop()
before being written back to EBP, but the final writeback to EBP is done using
the size indicated by mo_stacksize().

In the case where mo_pushpop() is MO_32 and mo_stacksize() is MO_16 then the
final writeback to EBP is done using MO_16 which can leave junk in the top
16-bits of EBP after executing ENTER.

Change the writeback of EBP to use the same size indicated by mo_pushpop() to
ensure that the full value is written back.

Signed-off-by: Mark Cave-Ayland <[email protected]>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2198
Message-ID: <[email protected]>
Cc: [email protected]
Signed-off-by: Paolo Bonzini <[email protected]>

Author: mcayland

target/i386/tcg/translate.c

@@ -2138,7 +2138,7 @@ static void gen_enter(DisasContext *s, int esp_addend, int level)
     }
 
     /* Copy the FrameTemp value to EBP.  */
-    gen_op_mov_reg_v(s, a_ot, R_EBP, s->T1);
+    gen_op_mov_reg_v(s, d_ot, R_EBP, s->T1);
 
     /* Compute the final value of ESP.  */
     tcg_gen_subi_tl(s->T1, s->T1, esp_addend + size * level);