On 10/19/24 09:39, Julian Ganz wrote:
We recently introduced new plugin API for registration of trap related
callbacks. This change introduces a minimal plugin showcasing the new
API. It simply counts the occurances of interrupts, exceptions and
semihosting events per CPU and reports the counts when exitting.
Signed-off-by: Julian Ganz <neither@nut.email>
---
contrib/plugins/Makefile | 1 +
contrib/plugins/traps.c | 89 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 90 insertions(+)
create mode 100644 contrib/plugins/traps.c
diff --git a/contrib/plugins/Makefile b/contrib/plugins/Makefile
index bbddd4800f..6085fd701f 100644
--- a/contrib/plugins/Makefile
+++ b/contrib/plugins/Makefile
@@ -31,6 +31,7 @@ NAMES += drcov
NAMES += ips
NAMES += stoptrigger
NAMES += cflow
+NAMES += traps
ifeq ($(CONFIG_WIN32),y)
SO_SUFFIX := .dll
diff --git a/contrib/plugins/traps.c b/contrib/plugins/traps.c
new file mode 100644
index 0000000000..2a38dbb8b3
--- /dev/null
+++ b/contrib/plugins/traps.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2024, Julian Ganz <neither@nut.email>
+ *
+ * Traps - count traps
+ *
+ * License: GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <stdio.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+typedef struct {
+ uint64_t interrupts;
+ uint64_t exceptions;
+ uint64_t semihosting;
+ bool active;
+} TrapCounters;
+
+static TrapCounters *traps;
+size_t max_vcpus;
+
+static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ traps[vcpu_index].active = true;
+}
+
+static void vcpu_interrupt(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ traps[vcpu_index].interrupts++;
+}
+
+static void vcpu_exception(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ traps[vcpu_index].exceptions++;
+}
+
+static void vcpu_semihosting(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ traps[vcpu_index].semihosting++;
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+ g_autoptr(GString) report;
+ report = g_string_new("VCPU, interrupts, exceptions, semihosting\n");
+ int vcpu;
+
+ for (vcpu = 0; vcpu < max_vcpus; vcpu++) {
+ TrapCounters *rec = &traps[vcpu];
+ if (rec->active) {
+ g_string_append_printf(report,
+ "% 4d, % 10"PRId64", % 10"PRId64", % 10"
+ PRId64"\n",
+ vcpu,
+ rec->interrupts, rec->exceptions,
+ rec->semihosting);
+ }
+ }
+
+ qemu_plugin_outs(report->str);
+}
+
+QEMU_PLUGIN_EXPORT
+int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
+ int argc, char **argv)
+{
+ if (!info->system_emulation) {
+ fputs("trap plugin can only be used in system emulation mode.\n",
+ stderr);
+ return -1;
+ }
+
+ max_vcpus = info->system.max_vcpus;
+ traps = calloc(max_vcpus, sizeof(TrapCounters));
Instead of allocating data for max number of vcpu, you can use a
qemu_plugin_scoreboard, which was introduced recently, and covers
exactly this need, by providing an array that gets automatically
redimensioned when a vcpu is added.
A simple example using it can be found with bb plugin:
https://gitlab.com/qemu-project/qemu/-/blob/master/tests/tcg/plugins/bb.c
+ qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
+ qemu_plugin_vcpu_for_each(id, vcpu_init);
+
+ qemu_plugin_register_vcpu_interrupt_cb(id, vcpu_interrupt);
+ qemu_plugin_register_vcpu_exception_cb(id, vcpu_exception);
+ qemu_plugin_register_vcpu_semihosting_cb(id, vcpu_semihosting);
+
+ qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+
+ return 0;
+}
