Re: [Qemu-devel] [PATCH v3 01/10] tcg-runtime: add lookup_tb_ptr helper

[Richard Henderson]

On 04/26/2017 12:29 PM, Alex Bennée wrote:
> Emilio G. Cota <address@hidden> writes:
>
> > This paves the way for upcoming work.
> >
> > Reviewed-by: Richard Henderson <address@hidden>
> > Signed-off-by: Emilio G. Cota <address@hidden>
> > ---
> >   tcg-runtime.c     | 21 +++++++++++++++++++++
> >   tcg/tcg-runtime.h |  2 ++
> >   tcg/tcg.h         |  1 +
> >   3 files changed, 24 insertions(+)
> >
> > diff --git a/tcg-runtime.c b/tcg-runtime.c
> > index 4c60c96..90d2d4b 100644
> > --- a/tcg-runtime.c
> > +++ b/tcg-runtime.c
> > @@ -27,6 +27,7 @@
> >   #include "exec/helper-proto.h"
> >   #include "exec/cpu_ldst.h"
> >   #include "exec/exec-all.h"
> > +#include "exec/tb-hash.h"
> >
> >   /* 32-bit helpers */
> >
> > @@ -141,6 +142,26 @@ uint64_t HELPER(ctpop_i64)(uint64_t arg)
> >       return ctpop64(arg);
> >   }
> >
> > +void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr)
> > +{
> > +    CPUState *cpu = ENV_GET_CPU(env);
> > +    TranslationBlock *tb;
> > +    target_ulong cs_base, pc;
> > +    uint32_t flags;
> > +
> > +    if (unlikely(atomic_read(&cpu->exit_request))) {
> > +        goto out_epilogue;
> > +    }
> > +    cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
> > +    tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)]);
> > +    if (likely(tb && tb->pc == addr && tb->cs_base == cs_base &&
> > +               tb->flags == flags)) {
>
> Should we also not be checking the TB hasn't been invalidated: tb->invalid?

We don't check in tb_find.

I guess we're assuming that such have been purged from the tb_jmp_cache.  That 
said, tb_phys_invalidate assumes tb_locked, and I don't immediately remember 
how all that is supposed to tie together.


r~