Re: [PATCH 47/82] target/arm: Expand pstate to 64 bits

[Richard Henderson <richard.henderson@linaro.org>]

On 8/1/25 05:13, Pierrick Bouvier wrote:
> On 7/27/25 1:02 AM, Richard Henderson wrote:
>> The ARM now defines 36 bits in SPSR_ELx in aarch64 mode, so
>> it's time to bite the bullet and extend PSTATE to match.
>>
>> Most changes are straightforward, adjusting printf formats,
>> changing local variable types.  More complex is migration,
>> where to maintain backward compatibility a new pstate64
>> record is introduced, and only when one of the extensions
>> that sets bits 32-35 are active.
>>
>> The fate of gdbstub is left undecided for the moment.
...
>> diff --git a/target/arm/gdbstub64.c b/target/arm/gdbstub64.c
>> index 64ee9b3b56..3cef47281a 100644
>> --- a/target/arm/gdbstub64.c
>> +++ b/target/arm/gdbstub64.c
>> @@ -47,6 +47,7 @@ int aarch64_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, 
>> int n)
>>       case 32:
>>           return gdb_get_reg64(mem_buf, env->pc);
>>       case 33:
>> +        /* pstate is now a 64-bit value; can we simply adjust the xml? */
>>           return gdb_get_reg32(mem_buf, pstate_read(env));
>>       }
> 
> If I'm correct, we currently don't expose PSTATE through gdbstub, but only CPSR. This was 
> a bit confusing for me, considering that CPSR is not even supposed to exist in Aarch64.

Correct.  An old error, for sure.


> Maybe it's a good opportunity to expose PSTATE instead, which could have a 64 bits size. 
> This way, we don't break any workflow.

Hmm, perhaps adding a "org.gnu.gdb.aarch64.pstate" xml with just one 64-bit value is the 
best solution.  Thiago?


r~