Re: ARM: ptw.c:S1_ptw_translate

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Cc'ing Richard & qemu-arm list.

On 4/1/23 17:55, Sid Manning wrote:
> ptw.c:S1_ptw_translate
> 
> After migrating to v7.2.0, an issue was found where we were not getting 
> the correct virtual address from a load insn.  Reading the address used 
> in the load insn from the debugger resulted in the execution of the insn 
> getting the correct value but simply stepping over the insn did not.
> 
> This is the instruction:
> 
> ldr           x0, [x1, #24]
> 
> The debug path varies based on the regime and if regime is NOT stage two 
> out_phys is set to addr if the regime is stage 2 then out_phys is set to 
> s2.f.phys_addr.  In the non-debug path out_phys is always set to 
> full->phys_addr.
> 
> I got around this by only using full->phys_addr if regime_is_stage2 was 
> true:
> 
> diff --git a/target/arm/ptw.c b/target/arm/ptw.c
> 
> index 3745ac9723..87bc6754a6 100644
> 
> --- a/target/arm/ptw.c
> 
> +++ b/target/arm/ptw.c
> 
> @@ -266,7 +266,12 @@ static bool S1_ptw_translate(CPUARMState *env, 
> S1Translate *ptw,
> 
>           if (unlikely(flags & TLB_INVALID_MASK)) {
> 
>               goto fail;
> 
>           }
> 
> -        ptw->out_phys = full->phys_addr;
> 
> +
> 
> +        if (regime_is_stage2(s2_mmu_idx)) {
> 
> +            ptw->out_phys = full->phys_addr;
> 
> +        } else {
> 
> +            ptw->out_phys = addr;
> 
> +        }
> 
>           ptw->out_rw = full->prot & PAGE_WRITE;
> 
>           pte_attrs = full->pte_attrs;
> 
>           pte_secure = full->attrs.secure;
> 
> This change got me the answer I wanted but I’m not familiar enough with 
> the code to know if this is correct or not.
>