We recently introduced new plugin API for registration of discontinuity
related callbacks. This change introduces a minimal plugin showcasing
the new API. It simply counts the occurances of interrupts, exceptions
and host calls per CPU and reports the counts when exitting.
Signed-off-by: Julian Ganz <neither@nut.email>
---
contrib/plugins/meson.build | 3 +-
contrib/plugins/traps.c | 100 ++++++++++++++++++++++++++++++++++++
docs/about/emulation.rst | 8 +++
3 files changed, 110 insertions(+), 1 deletion(-)
create mode 100644 contrib/plugins/traps.c
diff --git a/contrib/plugins/meson.build b/contrib/plugins/meson.build
index fa8a426c8b..327b48c888 100644
--- a/contrib/plugins/meson.build
+++ b/contrib/plugins/meson.build
@@ -1,5 +1,6 @@
contrib_plugins = ['bbv', 'cache', 'cflow', 'drcov', 'execlog', 'hotblocks',
- 'hotpages', 'howvec', 'hwprofile', 'ips', 'stoptrigger']
+ 'hotpages', 'howvec', 'hwprofile', 'ips', 'stoptrigger',
+ 'traps']
if host_os != 'windows'
# lockstep uses socket.h
contrib_plugins += 'lockstep'
diff --git a/contrib/plugins/traps.c b/contrib/plugins/traps.c
new file mode 100644
index 0000000000..5fa5a853ee
--- /dev/null
+++ b/contrib/plugins/traps.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2025, Julian Ganz <neither@nut.email>
+ *
+ * Traps - count traps
+ *
+ * Count the number of interrupts (asyncronous events), exceptions (synchronous
+ * events) and host calls (e.g. semihosting) per cpu and report those counts on
+ * exit.
+ *
+ * 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 hostcalls;
+ bool active;
+} TrapCounters;
+
+static struct qemu_plugin_scoreboard *traps;
+static size_t max_vcpus;
+
+static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index)
+{
+ TrapCounters *rec = qemu_plugin_scoreboard_find(traps, vcpu_index);
+ rec->active = true;
+}
+
+static void vcpu_discon(qemu_plugin_id_t id, unsigned int vcpu_index,
+ enum qemu_plugin_discon_type type, uint64_t from_pc,
+ uint64_t to_pc)
+{
+ TrapCounters *rec = qemu_plugin_scoreboard_find(traps, vcpu_index);
+ switch (type) {
+ case QEMU_PLUGIN_DISCON_INTERRUPT:
+ rec->interrupts++;
+ break;
+ case QEMU_PLUGIN_DISCON_EXCEPTION:
+ rec->exceptions++;
+ break;
+ case QEMU_PLUGIN_DISCON_HOSTCALL:
+ rec->hostcalls++;
+ break;
+ default:
+ g_assert_not_reached();
+ break;
+ }
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+ g_autoptr(GString) report;
+ report = g_string_new("VCPU, interrupts, exceptions, hostcalls\n");
+ int vcpu;
+
+ for (vcpu = 0; vcpu < max_vcpus; vcpu++) {
+ TrapCounters *rec = qemu_plugin_scoreboard_find(traps, vcpu);
+ if (rec->active) {
+ g_string_append_printf(report,
+ "% 4d, % 10"PRId64", % 10"PRId64", % 10"
+ PRId64"\n",
+ vcpu,
+ rec->interrupts, rec->exceptions,
+ rec->hostcalls);
+ }
+ }
+
+ qemu_plugin_outs(report->str);
+ qemu_plugin_scoreboard_free(traps);
+}
+
+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 = qemu_plugin_scoreboard_new(sizeof(TrapCounters));
+ qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
+ qemu_plugin_vcpu_for_each(id, vcpu_init);
+
+ qemu_plugin_register_vcpu_discon_cb(id, QEMU_PLUGIN_DISCON_ALL,
+ vcpu_discon);
+
+ qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+
+ return 0;
+}
diff --git a/docs/about/emulation.rst b/docs/about/emulation.rst
index a72591ee4d..f985fce8ec 100644
--- a/docs/about/emulation.rst
+++ b/docs/about/emulation.rst
@@ -812,6 +812,14 @@ This plugin can limit the number of Instructions Per
Second that are executed::
- Maximum number of instructions per cpu that can be executed in one
second.
The plugin will sleep when the given number of instructions is reached.
+Count traps
+...........
+
+``contrib/plugins/traps.c``
+
+This plugin counts the number of interrupts (asyncronous events), exceptions
+(synchronous events) and host calls (e.g. semihosting) per cpu.
+
Other emulation features
------------------------
--
2.49.0
