target/arm: Clean up some corner cases of sysreg traps

[PATCH 11/14] target/arm: Use TRAP_UNCATEGORIZED for XScale CPAR traps

Posted by Peter Maydell 2 months, 1 week ago

On XScale CPUs, there is no EL2 or AArch64, so no syndrome register.
These traps are just UNDEFs in the traditional AArch32 sense, so
CP_ACCESS_TRAP_UNCATEGORIZED is more accurate than CP_ACCESS_TRAP.
This has no visible behavioural change, because the guest doesn't
have a way to see the syndrome value we generate.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/tcg/op_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/arm/tcg/op_helper.c b/target/arm/tcg/op_helper.c
index c427118655d..c69d2ac643f 100644
--- a/target/arm/tcg/op_helper.c
+++ b/target/arm/tcg/op_helper.c
@@ -764,7 +764,7 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key,
 
     if (arm_feature(env, ARM_FEATURE_XSCALE) && ri->cp < 14
         && extract32(env->cp15.c15_cpar, ri->cp, 1) == 0) {
-        res = CP_ACCESS_TRAP;
+        res = CP_ACCESS_TRAP_UNCATEGORIZED;
         goto fail;
     }
 
-- 
2.34.1

Re: [PATCH 11/14] target/arm: Use TRAP_UNCATEGORIZED for XScale CPAR traps

Posted by Richard Henderson 2 months ago

On 1/30/25 10:23, Peter Maydell wrote:
> On XScale CPUs, there is no EL2 or AArch64, so no syndrome register.
> These traps are just UNDEFs in the traditional AArch32 sense, so
> CP_ACCESS_TRAP_UNCATEGORIZED is more accurate than CP_ACCESS_TRAP.
> This has no visible behavioural change, because the guest doesn't
> have a way to see the syndrome value we generate.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/arm/tcg/op_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

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

r~

Re: [PATCH 11/14] target/arm: Use TRAP_UNCATEGORIZED for XScale CPAR traps

Posted by Philippe Mathieu-Daudé 2 months, 1 week ago

On 30/1/25 19:23, Peter Maydell wrote:
> On XScale CPUs, there is no EL2 or AArch64, so no syndrome register.
> These traps are just UNDEFs in the traditional AArch32 sense, so
> CP_ACCESS_TRAP_UNCATEGORIZED is more accurate than CP_ACCESS_TRAP.
> This has no visible behavioural change, because the guest doesn't
> have a way to see the syndrome value we generate.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   target/arm/tcg/op_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>