Re: [PATCH v4 21/23] tests: add plugin asserting correctness of discon event's to_pc

["Julian Ganz" <nenut@skiff.uberspace.de>]

Hi Pierrick,

May 13, 2025 at 9:45 AM, Julian Ganz wrote:
> May 13, 2025 at 2:25 AM, Pierrick Bouvier wrote:
> > [...]
> >  + if (trace_all_insns) {
> >  + g_autoptr(GString) report = g_string_new(NULL);
> >  + g_string_append_printf(report, "Exec insn at %"PRIx64" on VCPU %d\n",
> >  + insn->addr, vcpu_index);
> >  + qemu_plugin_outs(report->str);
> >  + }
> >  +}
> >  +
> >  +static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
> >  +{
> >  + size_t i;
> >  + size_t n_insns = qemu_plugin_tb_n_insns(tb);
> >  + struct insn_data *udata = calloc(n_insns, sizeof(struct insn_data));
> >  +
> >  
> >  With this, for every TB translated, we'll perform an allocation, and then lose track of the pointer. It's usually a pain to pass this kind of "dynamic" information through udata.
> >  
> >  A more elegant solution is to perform a QEMU_PLUGIN_INLINE_STORE_U64 to store this information under a new cpu_state.current_insn field directly.
> >  Callbacks are installed in the order you register them, so by storing information inline *before* the insn_exec callback, it will work as expected, as cpu_static.current_insn will be already updated.
> >  You can find some other plugins which use this trick.
> > 
> Mh... Thanks for the hint. I'll have a closer look later.
> 
> I also wonder whether this could also be useful for solving the issue we
> run into with virtual memory: TBs being reused in a context different
> from the one may have a different addresses. That's why we introduced
> the compare-addr-bits argument.

Never mind, I had a look at what the API allows for. Your apporach looks
reasonable. I'll implement it the way you suggested.

Regards,
Julian