[Qemu-devel] Re: [PATCH 08/15] Clean up slb_lookup() function

[Alexander Graf]

On 12.02.2011, at 15:54, David Gibson wrote:

> The slb_lookup() function, used in the ppc translation path returns a
> number of slb entry fields in reference parameters.  However, only one
> of the two callers of slb_lookup() actually wants this information.
> 
> This patch, therefore, makes slb_lookup() return a simple pointer to the
> located SLB entry (or NULL), and the caller which needs the fields can
> extract them itself.
> 
> Signed-off-by: David Gibson <address@hidden>
> ---
> target-ppc/helper.c |   45 ++++++++++++++++++---------------------------
> 1 files changed, 18 insertions(+), 27 deletions(-)
> 
> diff --git a/target-ppc/helper.c b/target-ppc/helper.c
> index 4830981..73d93ca 100644
> --- a/target-ppc/helper.c
> +++ b/target-ppc/helper.c
> @@ -672,9 +672,7 @@ static inline int find_pte(CPUState *env, mmu_ctx_t *ctx, 
> int h, int rw,
> }
> 
> #if defined(TARGET_PPC64)
> -static inline int slb_lookup(CPUPPCState *env, target_ulong eaddr,
> -                             target_ulong *vsid, target_ulong *page_mask,
> -                             int *attr, int *target_page_bits)
> +static inline ppc_slb_t *slb_lookup(CPUPPCState *env, target_ulong eaddr)
> {
>     uint64_t esid;
>     int n;
> @@ -689,19 +687,11 @@ static inline int slb_lookup(CPUPPCState *env, 
> target_ulong eaddr,
>         LOG_SLB("%s: slot %d %016" PRIx64 " %016"
>                     PRIx64 "\n", __func__, n, slb->esid, slb->vsid);
>         if (slb->esid == esid) {
> -            *vsid = (slb->vsid & SLB_VSID_VSID) >> SLB_VSID_SHIFT;
> -            *page_mask = ~SEGMENT_MASK_256M;
> -            *attr = slb->vsid & SLB_VSID_ATTR;
> -            if (target_page_bits) {
> -                *target_page_bits = (slb->vsid & SLB_VSID_L)
> -                    ? TARGET_PAGE_BITS_16M
> -                    : TARGET_PAGE_BITS;
> -            }
> -            return n;
> +            return slb;
>         }
>     }
> 
> -    return -5;
> +    return NULL;

Hah - there goes the -5 :).

> }
> 
> void ppc_slb_invalidate_all (CPUPPCState *env)
> @@ -728,18 +718,13 @@ void ppc_slb_invalidate_all (CPUPPCState *env)
> 
> void ppc_slb_invalidate_one (CPUPPCState *env, uint64_t T0)
> {
> -    target_ulong vsid, page_mask;
> -    int attr;
> -    int n;
>     ppc_slb_t *slb;
> 
> -    n = slb_lookup(env, T0, &vsid, &page_mask, &attr, NULL);
> -    if (n < 0) {
> +    slb = slb_lookup(env, T0);
> +    if (!slb) {
>         return;
>     }
> 
> -    slb = &env->slb[n];
> -
>     if (slb->esid & SLB_ESID_V) {
>         slb->esid &= ~SLB_ESID_V;
> 
> @@ -818,16 +803,22 @@ static inline int get_segment(CPUState *env, mmu_ctx_t 
> *ctx,
>     pr = msr_pr;
> #if defined(TARGET_PPC64)
>     if (env->mmu_model & POWERPC_MMU_64) {
> -        int attr;
> +        ppc_slb_t *slb;
> 
>         LOG_MMU("Check SLBs\n");
> -        ret = slb_lookup(env, eaddr, &vsid, &page_mask, &attr,
> -                         &target_page_bits);
> -        if (ret < 0)
> -            return ret;
> -        ctx->key = !!(pr ? (attr & SLB_VSID_KP) : (attr & SLB_VSID_KS));
> +        slb = slb_lookup(env, eaddr);
> +        if (!slb) {
> +            return -5;

And here it comes again - sigh :). Well, can't be helped. This at least keeps 
the current logic as is.
Very nice patch.

Acked-by: Alexander Graf <address@hidden>


Alex