On Thu, 18 Feb 2021 at 09:47, Alex Bennée <alex.ben...@linaro.org> wrote:
>
> There is no real need to use CF_NOCACHE here. As long as the TB isn't
> linked to other TBs or included in the QHT or jump cache then it will
> only get executed once.
>
> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
> Message-Id: <20210213130325.14781-19-alex.ben...@linaro.org>
Hi; I've just noticed that this commit seems to break the case of:
* execution of code not from a RAM block
* when icount is enabled
* and an instruction is an IO insn that triggers io-recompile
because:
> @@ -2097,6 +2086,17 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
> tb_reset_jump(tb, 1);
> }
>
> + /*
> + * If the TB is not associated with a physical RAM page then
> + * it must be a temporary one-insn TB, and we have nothing to do
> + * except fill in the page_addr[] fields. Return early before
> + * attempting to link to other TBs or add to the lookup table.
> + */
> + if (phys_pc == -1) {
> + tb->page_addr[0] = tb->page_addr[1] = -1;
> + return tb;
> + }
we used to fall through here, which meant we called
tcg_tb_insert(tb). No we no longer do. That's bad, because
cpu_io_recompile() does:
tb = tcg_tb_lookup(retaddr);
if (!tb) {
cpu_abort(cpu, "cpu_io_recompile: could not find TB for pc=%p",
(void *)retaddr);
}
and since it can no longer find the TB, QEMU aborts.
thanks
-- PMM
