Add skeleton implementation of tracing plugin.

Author: Rot127

contrib/plugins/execlog_bap.c

@@ -0,0 +1,74 @@
+// SPDX-FileCopyrightText: 2025 Rot127 <[email protected]>
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+typedef struct {
+  // Current instruction related things.
+} VCPU;
+
+typedef struct {
+  GRWLock vcpus_array_lock;
+  GArray *vcpus;
+
+  GRWLock frame_buffer_lock;
+  GPtrArray *frame_buffer;
+} TraceState;
+
+static TraceState state;
+
+static VCPU *get_vcpu(TraceState *state, int vcpu_index) {
+  VCPU *c;
+  g_rw_lock_reader_lock(&state->vcpus_array_lock);
+  c = &g_array_index(state->vcpus, VCPU, vcpu_index);
+  g_rw_lock_reader_unlock(&state->vcpus_array_lock);
+
+  return c;
+}
+
+static void log_insn_frame(unsigned int cpu_index, void *udata) {
+  // VCPU *vcpu = get_vcpu(state, cpu_index);
+
+  // Add change to previous frame
+  // Finish previous frame
+  // Check if buffer should be dumped to file.
+  // Open new one.
+  return;
+}
+
+static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index) {
+  // Add new vcpu
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *udata) {
+  // Dump rest of frames to file.
+}
+
+static void cb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) {
+  // Add a callback for each instruction in every translated block.
+  struct qemu_plugin_insn *insn;
+  size_t n_insns = qemu_plugin_tb_n_insns(tb);
+  for (size_t i = 0; i < n_insns; i++) {
+    insn = qemu_plugin_tb_get_insn(tb, i);
+    qemu_plugin_register_vcpu_insn_exec_cb(insn, log_insn_frame,
+                                           QEMU_PLUGIN_CB_R_REGS, &state);
+  }
+}
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+                                           const qemu_info_t *info, int argc,
+                                           char **argv) {
+  qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
+  qemu_plugin_register_vcpu_tb_trans_cb(id, cb_trans);
+  qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+
+  // Get reg names
+  // qemu_plugin_get_registers
+  //
+  // Logging
+  // qemu_plugin_outs
+
+  return 0;
+}