target/arm: Fix various underdecodings

[Qemu-devel] [PATCH 2/7] target/arm/translate-a64: Don't underdecode PRFM

Posted by Peter Maydell 6 years, 9 months ago

The PRFM prefetch insn in the load/store with imm9 encodings
requires idx field 0b00; we were underdecoding this by
only checking !is_unpriv (which is equivalent to idx != 2).
Correctly UNDEF the unallocated encodings where idx == 0b01
and 0b11 as well as 0b10.

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/translate-a64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index e6df303e321..8e081758e03 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -2803,7 +2803,7 @@ static void disas_ldst_reg_imm9(DisasContext *s, uint32_t insn,
     } else {
         if (size == 3 && opc == 2) {
             /* PRFM - prefetch */
-            if (is_unpriv) {
+            if (idx != 0) {
                 unallocated_encoding(s);
                 return;
             }
-- 
2.20.1

Re: [Qemu-devel] [PATCH 2/7] target/arm/translate-a64: Don't underdecode PRFM

Posted by Laurent Desnogues 6 years, 9 months ago

On Fri, Jan 25, 2019 at 7:26 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> The PRFM prefetch insn in the load/store with imm9 encodings
> requires idx field 0b00; we were underdecoding this by
> only checking !is_unpriv (which is equivalent to idx != 2).
> Correctly UNDEF the unallocated encodings where idx == 0b01
> and 0b11 as well as 0b10.
>
> Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>

Thanks,

Laurent

> ---
>  target/arm/translate-a64.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
> index e6df303e321..8e081758e03 100644
> --- a/target/arm/translate-a64.c
> +++ b/target/arm/translate-a64.c
> @@ -2803,7 +2803,7 @@ static void disas_ldst_reg_imm9(DisasContext *s, uint32_t insn,
>      } else {
>          if (size == 3 && opc == 2) {
>              /* PRFM - prefetch */
> -            if (is_unpriv) {
> +            if (idx != 0) {
>                  unallocated_encoding(s);
>                  return;
>              }
> --
> 2.20.1
>