diff mbox series

[1/7] arm: Don't implement BXJ on M-profile CPUs

Message ID 1491820793-5348-2-git-send-email-peter.maydell@linaro.org
State Superseded
Headers show
Series arm: Implement M profile exception return properly | expand

Commit Message

Peter Maydell April 10, 2017, 10:39 a.m. UTC 
For M-profile CPUs, the BXJ instruction does not exist at all, and
the encoding should always UNDEF. We were accidentally implementing
it to behave like A-profile BXJ; correct the error.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

---
 target/arm/translate.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

-- 
2.7.4

Comments

Philippe Mathieu-Daudé April 10, 2017, 11:43 a.m. UTC | #1 
On 04/10/2017 07:39 AM, Peter Maydell wrote:
> For M-profile CPUs, the BXJ instruction does not exist at all, and

> the encoding should always UNDEF. We were accidentally implementing

> it to behave like A-profile BXJ; correct the error.

>

> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>


Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>


> ---

>  target/arm/translate.c | 7 ++++++-

>  1 file changed, 6 insertions(+), 1 deletion(-)

>

> diff --git a/target/arm/translate.c b/target/arm/translate.c

> index e32e38c..fe3f442 100644

> --- a/target/arm/translate.c

> +++ b/target/arm/translate.c

> @@ -10485,7 +10485,12 @@ static int disas_thumb2_insn(CPUARMState *env, DisasContext *s, uint16_t insn_hw

>                          }

>                          break;

>                      case 4: /* bxj */

> -                        /* Trivial implementation equivalent to bx.  */

> +                        /* Trivial implementation equivalent to bx.

> +                         * This instruction doesn't exist at all for M-profile.

> +                         */

> +                        if (arm_dc_feature(s, ARM_FEATURE_M)) {

> +                            goto illegal_op;

> +                        }

>                          tmp = load_reg(s, rn);

>                          gen_bx(s, tmp);

>                          break;

>
diff mbox series

Patch

diff --git a/target/arm/translate.c b/target/arm/translate.c
index e32e38c..fe3f442 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10485,7 +10485,12 @@  static int disas_thumb2_insn(CPUARMState *env, DisasContext *s, uint16_t insn_hw
                         }
                         break;
                     case 4: /* bxj */
-                        /* Trivial implementation equivalent to bx.  */
+                        /* Trivial implementation equivalent to bx.
+                         * This instruction doesn't exist at all for M-profile.
+                         */
+                        if (arm_dc_feature(s, ARM_FEATURE_M)) {
+                            goto illegal_op;
+                        }
                         tmp = load_reg(s, rn);
                         gen_bx(s, tmp);
                         break;