plugins: Set final instruction count in plugin_gen_tb_end

Translation logic may partially decode an instruction, then abort and
remove the instruction from the TB. This can happen for example when an
instruction spans two pages. In this case, plugins may get an incorrect
result when calling qemu_plugin_tb_n_insns to query for the number of
instructions in the TB. This patch updates plugin_gen_tb_end to set the
final instruction count.

Signed-off-by: Matt Borgerson <contact@mborgerson.com>
[AJB: added g_assert to defed API]
Message-Id: <CADc=-s5RwGViNTR-h5cq3np673W3RRFfhr4vCGJp0EoDUxvhog@mail.gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231009164104.369749-23-alex.bennee@linaro.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
index d31c9993ea..39b3c9351f 100644
--- a/accel/tcg/plugin-gen.c
+++ b/accel/tcg/plugin-gen.c
@@ -866,10 +866,14 @@ void plugin_gen_insn_end(void)
  * do any clean-up here and make sure things are reset in
  * plugin_gen_tb_start.
  */
-void plugin_gen_tb_end(CPUState *cpu)
+void plugin_gen_tb_end(CPUState *cpu, size_t num_insns)
 {
     struct qemu_plugin_tb *ptb = tcg_ctx->plugin_tb;
 
+    /* translator may have removed instructions, update final count */
+    g_assert(num_insns <= ptb->n);
+    ptb->n = num_insns;
+
     /* collect instrumentation requests */
     qemu_plugin_tb_trans_cb(cpu, ptb);