Re: [Qemu-devel] [PATCH v5 2/3] softmmu: Add probe_write()

[Yongbok Kim <yongbok.kim@imgtec.com>]

On 26/05/2015 18:33, Richard Henderson wrote:
> On 05/26/2015 09:53 AM, Peter Maydell wrote:
>> On 26 May 2015 at 17:49, Yongbok Kim <yongbok.kim@imgtec.com> wrote:
>>> Add probe_write() forces a tlb_fill if the specified guest virtual
>>> index isn't in the TCG softmmu TLB.
>>
>> Surely the point is not to fill the TLB but to raise an
>> exception if the address is not writable?
>>
>>> +#if DATA_SIZE == 1
>>> +/*
>>> + * Force a tlb_fill if the specified guest virtual index isn't in the TCG
>>> + * softmmu TLB.
>>> + */
>>> +void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
>>> +                 uintptr_t retaddr)
>>> +{
>>> +    int index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
>>> +    target_ulong tlb_addr = env->tlb_table[mmu_idx][index].addr_write;
>>> +
>>> +    if ((addr & TARGET_PAGE_MASK)
>>> +        != (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK))) {
>>> +        /* TLB entry is for a different page */
>>> +        if (!VICTIM_TLB_HIT(addr_write)) {
>>> +            tlb_fill(ENV_GET_CPU(env), addr, MMU_DATA_STORE, mmu_idx, retaddr);
>>> +        }
>>> +    }
>>> +}
>>> +#endif
>>>  #endif /* !defined(SOFTMMU_CODE_ACCESS) */
>>
>> I think this code does what you want, but the comments are
>> rather misleading...
> 
> Indeed.  The fact that the TLB gets loaded is merely a happy side-effect.
> 
> 
> r~
> 

Agreed, I will change the description.

Regards,
Yongbok