Re: [PATCH v2 2/5] target/arm: Ensure icount is enabled when emulating INST_RETIRED

[Philippe Mathieu-Daudé]

On 7/12/23 23:12, Richard Henderson wrote:
> On 12/7/23 07:45, Philippe Mathieu-Daudé wrote:
> > pmu_init() register its event checking the pm_event::supported()
> > handler. For INST_RETIRED, the event is only registered and the
> > bit enabled in the PMU Common Event Identification register when
> > icount is enabled as ICOUNT_PRECISE.
> >
> > Assert the pm_event::get_count() and pm_event::ns_per_count()
> > handler will only be called under this icount mode.
> >
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> >   target/arm/helper.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/target/arm/helper.c b/target/arm/helper.c
> > index adb0960bba..333fd5f4bf 100644
> > --- a/target/arm/helper.c
> > +++ b/target/arm/helper.c
> > @@ -940,11 +940,13 @@ static bool instructions_supported(CPUARMState 
> > *env)
> >   static uint64_t instructions_get_count(CPUARMState *env)
> >   {
> > +    assert(icount_enabled() == ICOUNT_PRECISE);
> >       return (uint64_t)icount_get_raw();
> >   }
> >   static int64_t instructions_ns_per(uint64_t icount)
> >   {
> > +    assert(icount_enabled() == ICOUNT_PRECISE);
> >       return icount_to_ns((int64_t)icount);
> >   }
> >   #endif
>
> I don't think an assert is required -- that's exactly what the 
> .supported field is for. If you think this needs additional 
> clarification, a comment is sufficient.

Without this I'm getting this link failure with TCG disabled:

ld: Undefined symbols:
  _icount_to_ns, referenced from:
      _instructions_ns_per in target_arm_helper.c.o
clang: error: linker command failed with exit code 1 (use -v to see 
invocation)