[PATCH v2 4/7] target/arm: Present AArch64 gdbstub based on ARM_FEATURE_AARCH64

Peter Maydell posted 7 patches 6 months, 2 weeks ago
Maintainers: Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Peter Maydell <peter.maydell@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
[PATCH v2 4/7] target/arm: Present AArch64 gdbstub based on ARM_FEATURE_AARCH64
Posted by Peter Maydell 6 months, 2 weeks ago
Currently we provide an AArch64 gdbstub for CPUs which are
TYPE_AARCH64_CPU, and an AArch32 gdbstub for those which are only
TYPE_ARM_CPU.  This mostly does the right thing, except in the
corner case of KVM with -cpu host,aarch64=off.  That produces a CPU
which is TYPE_AARCH64_CPU but which has ARM_FEATURE_AARCH64 removed
and which to the guest is in AArch32 mode.

Now we have moved all the handling of AArch64-vs-AArch32 gdbstub
behaviour into TYPE_ARM_CPU we can change the condition we use for
whether to select the AArch64 gdbstub to look at ARM_FEATURE_AARCH64.
This will mean that we now correctly provide an AArch32 gdbstub for
aarch64=off CPUs.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/arm/internals.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/arm/internals.h b/target/arm/internals.h
index 4d3d84ffebd..f1c06a3fd89 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1831,7 +1831,7 @@ void aarch64_add_sme_properties(Object *obj);
 /* Return true if the gdbstub is presenting an AArch64 CPU */
 static inline bool arm_gdbstub_is_aarch64(ARMCPU *cpu)
 {
-    return object_dynamic_cast(OBJECT(cpu), TYPE_AARCH64_CPU);
+    return arm_feature(&cpu->env, ARM_FEATURE_AARCH64);
 }
 
 /* Read the CONTROL register as the MRS instruction would. */
-- 
2.43.0


Re: [PATCH v2 4/7] target/arm: Present AArch64 gdbstub based on ARM_FEATURE_AARCH64
Posted by Richard Henderson 6 months, 2 weeks ago
On 4/29/25 06:21, Peter Maydell wrote:
> Currently we provide an AArch64 gdbstub for CPUs which are
> TYPE_AARCH64_CPU, and an AArch32 gdbstub for those which are only
> TYPE_ARM_CPU.  This mostly does the right thing, except in the
> corner case of KVM with -cpu host,aarch64=off.  That produces a CPU
> which is TYPE_AARCH64_CPU but which has ARM_FEATURE_AARCH64 removed
> and which to the guest is in AArch32 mode.
> 
> Now we have moved all the handling of AArch64-vs-AArch32 gdbstub
> behaviour into TYPE_ARM_CPU we can change the condition we use for
> whether to select the AArch64 gdbstub to look at ARM_FEATURE_AARCH64.
> This will mean that we now correctly provide an AArch32 gdbstub for
> aarch64=off CPUs.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé<philmd@linaro.org>
> ---
>   target/arm/internals.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~