Xingran Wang <wangxingran123...@outlook.com> writes: > Currently, the instruction count obtained by plugins using the translation > block execution callback is larger than the actual value. Adding callbacks > in cpu_restore_state_from_tb() and cpu_io_recompile() allows plugins to > correct the instruction count when exiting a translation block > mid-execution, properly subtracting the excess unexecuted > instructions.
This smells like exposing two much of the TCG internals to the plugin mechanism. You can already detect when we don't reach the end of a block of instructions by instrumentation as I did in: Message-Id: <20240718145958.1315270-1-alex.ben...@linaro.org> Date: Thu, 18 Jul 2024 15:59:58 +0100 Subject: [RFC PATCH v3] contrib/plugins: control flow plugin From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <alex.ben...@linaro.org> So what exactly are we trying to achieve here? A more efficient detection of short blocks? > > Signed-off-by: Xingran Wang <wangxingran123...@outlook.com> > --- > accel/tcg/translate-all.c | 27 ++++++++ > include/qemu/plugin-event.h | 2 + > include/qemu/plugin.h | 24 +++++++ > include/qemu/qemu-plugin.h | 131 +++++++++++++++++++++++++++++++++++ > plugins/api.c | 78 +++++++++++++++++++++ > plugins/core.c | 42 +++++++++++ > plugins/qemu-plugins.symbols | 10 +++ > tests/tcg/plugins/bb.c | 25 +++++++ > 8 files changed, 339 insertions(+) > > diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c > index fdf6d8ac19..642f684372 100644 > --- a/accel/tcg/translate-all.c > +++ b/accel/tcg/translate-all.c > @@ -65,6 +65,7 @@ > #include "internal-target.h" > #include "tcg/perf.h" > #include "tcg/insn-start-words.h" > +#include "qemu/plugin.h" > > TBContext tb_ctx; > > @@ -218,6 +219,19 @@ void cpu_restore_state_from_tb(CPUState *cpu, > TranslationBlock *tb, > cpu->neg.icount_decr.u16.low += insns_left; > } > > +#ifdef CONFIG_PLUGIN > + /* > + * Notify the plugin with the relevant information > + * when restoring the execution state of a TB. > + */ > + struct qemu_plugin_tb_restore ptb_restore; > + ptb_restore.cpu_index = cpu->cpu_index; > + ptb_restore.insns_left = insns_left; > + ptb_restore.tb_n = tb->icount; > + ptb_restore.tb_pc = tb->pc; > + qemu_plugin_tb_restore_cb(cpu, &ptb_restore); > +#endif > + See also the unwind patches which is a more generic approach to ensuring "special" registers are synced at midpoint when using the register API: Message-Id: <20240606032926.83599-1-richard.hender...@linaro.org> Date: Wed, 5 Jun 2024 20:29:17 -0700 Subject: [PATCH v2 0/9] plugins: Use unwind info for special gdb registers From: Richard Henderson <richard.hender...@linaro.org> <snip> -- Alex Bennée Virtualisation Tech Lead @ Linaro
