Re: [PATCH 3/3] target/hppa: fix building gva for wide mode

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

On 3/24/24 11:39, Richard Henderson wrote:
> On 3/23/24 22:09, Sven Schnelle wrote:
>> 64 Bit hppa no longer has a fixed 32/32 bit split between space and
>> offset. Instead it uses 42 bits for the offset. The lower 10 bits of
>> the space are always zero, leaving 22 bits actually used. Simply or
>> the values together to build the gva.
>>
>> Signed-off-by: Sven Schnelle <svens@stackframe.org>
>> ---
>>   target/hppa/mem_helper.c | 13 +++++++------
>>   1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
>> index 84785b5a5c..6f895fced7 100644
>> --- a/target/hppa/mem_helper.c
>> +++ b/target/hppa/mem_helper.c
>> @@ -523,13 +523,16 @@ void HELPER(itlbp_pa11)(CPUHPPAState *env, target_ulong addr, 
>> target_ulong reg)
>>   }
>>   static void itlbt_pa20(CPUHPPAState *env, target_ulong r1,
>> -                       target_ulong r2, vaddr va_b)
>> +                       target_ulong r2, uint64_t spc, uint64_t off)
>>   {
>>       HPPATLBEntry *ent;
>> -    vaddr va_e;
>> +    vaddr va_b, va_e;
>>       uint64_t va_size;
>>       int mask_shift;
>> +    va_b = off & gva_offset_mask(env->psw);
>> +    va_b |= spc << 32;
> 
> Actually, no, these instructions don't form a GVA in the normal fashion:
> 
> space ← ISR;
> offset ← cat(ISR{32..63},IOR{32..63});
> VIRTUAL_ADDR ← (space<<32) | (offset);
> 
>> -    vaddr va_b = deposit64(env->cr[CR_IOR], 32, 32, env->cr[CR_ISR]);
> 
> But this is wrong too.

Actually, no.  The

   VIRTUAL_ADDR = (space << 32) | offset

line constructs a 96-bit virtual address.  The low 32 bits of ISR have already replaced 
the high 32 bits of IOR, so this line really only adds the high 32 bits of space as bits 
[96:64] of the full virtual address.

Truncated to 64 bits, the deposit as written is exactly right.


r~