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

[PATCH 02/14] target/arm: Report correct syndrome for UNDEFINED AT ops with wrong NSE, NS

Posted by Peter Maydell 2 months ago

R_NYXTL says that these AT insns should be UNDEFINED if they
would operate on an EL lower than EL3 and SCR_EL3.{NSE,NS} is
set to the Reserved {1, 0}. We were incorrectly reporting
them with the wrong syndrome; use CP_ACCESS_TRAP_UNCATEGORIZED
so they are reported as UNDEFINED.

Cc: qemu-stable@nongnu.org
Fixes: 1acd00ef1410 ("target/arm/helper: Check SCR_EL3.{NSE, NS} encoding for AT instructions")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index c5245a20aaf..7ddeed0283f 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -3601,7 +3601,7 @@ static CPAccessResult at_e012_access(CPUARMState *env, const ARMCPRegInfo *ri,
      * scr_write() ensures that the NSE bit is not set otherwise.
      */
     if ((env->cp15.scr_el3 & (SCR_NSE | SCR_NS)) == SCR_NSE) {
-        return CP_ACCESS_TRAP;
+        return CP_ACCESS_TRAP_UNCATEGORIZED;
     }
     return CP_ACCESS_OK;
 }
-- 
2.34.1

Re: [PATCH 02/14] target/arm: Report correct syndrome for UNDEFINED AT ops with wrong NSE, NS

Posted by Richard Henderson 1 month, 3 weeks ago

On 1/30/25 10:22, Peter Maydell wrote:
> R_NYXTL says that these AT insns should be UNDEFINED if they
> would operate on an EL lower than EL3 and SCR_EL3.{NSE,NS} is
> set to the Reserved {1, 0}. We were incorrectly reporting
> them with the wrong syndrome; use CP_ACCESS_TRAP_UNCATEGORIZED
> so they are reported as UNDEFINED.
> 
> Cc:qemu-stable@nongnu.org
> Fixes: 1acd00ef1410 ("target/arm/helper: Check SCR_EL3.{NSE, NS} encoding for AT instructions")
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/arm/helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

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

r~