Re: [Qemu-devel] [PATCH v6 2/3] softmmu: Add probe_write()

[Peter Maydell]

On 27 May 2015 at 14:29, Yongbok Kim <address@hidden> wrote:
> Add probe_write() in order to support such functionality that probes
> if a specified guest virtual address exists in TLB and is writable.
> The function forces a tlb_fill() if the address does not exist or is
> not writable, as a result an exception can occur.
>
> Signed-off-by: Yongbok Kim <address@hidden>
> ---
>  include/exec/exec-all.h |    2 ++
>  softmmu_template.h      |   18 ++++++++++++++++++
>  2 files changed, 20 insertions(+), 0 deletions(-)
>
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index b58cd47..af51203 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -109,6 +109,8 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong 
> vaddr,
>                               hwaddr paddr, MemTxAttrs attrs,
>                               int prot, int mmu_idx, target_ulong size);
>  void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr);
> +void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
> +                 uintptr_t retaddr);
>  #else
>  static inline void tlb_flush_page(CPUState *cpu, target_ulong addr)
>  {
> diff --git a/softmmu_template.h b/softmmu_template.h
> index 9cb1659..1558b8b 100644
> --- a/softmmu_template.h
> +++ b/softmmu_template.h
> @@ -548,6 +548,24 @@ glue(glue(helper_st, SUFFIX), MMUSUFFIX)(CPUArchState 
> *env, target_ulong addr,
>      helper_te_st_name(env, addr, val, oi, GETRA());
>  }
>
> +#if DATA_SIZE == 1
> +/* Probe if the specified guest virtual address exists in TLB and is 
> writable,
> +   if not force a tlb_fill(). As a result an exception can occur. */

/* Probe for whether the specified guest write access is permitted.
 * If it is not permitted then an exception will be taken in the same
 * way as if this were a real write access (and we will not return).
 * Otherwise the function will return, and there will be a valid
 * entry in the TLB for this access.
 */

> +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) */
>
>  #undef READ_ACCESS_TYPE
> --

-- PMM