Save TOC entries when writing frames

Author: Rot127

contrib/plugins/bap-tracing/frame_buffer.c

@@ -159,6 +159,7 @@ bool frame_buffer_is_empty(const FrameBuffer *buf) {
   return buf->fbuf[buf->idx] == NULL;
 }
 
+/// @brief Dumps the file buffer as TOC entry into the file.
 void frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file) {
   for (size_t i = 0; i <= buf->idx && i < frames_per_toc_entry; ++i) {
     Frame *frame = buf->fbuf[i];
@@ -167,12 +168,10 @@ void frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file) {
     uint64_t packed_size = frame__pack(frame, packed_buffer);
     WRITE(packed_size);
     WRITE_BUF(packed_buffer, packed_size);
-    buf->frames_written++;
     frame_free(frame);
   }
   memset(buf->fbuf, 0, sizeof(buf->fbuf));
   buf->idx = 0;
-  // toc_update(); ??
 }
 
 bool frame_buffer_new_frame_std(FrameBuffer *buf, unsigned int thread_id,

contrib/plugins/bap-tracing/frame_buffer.h

@@ -20,7 +20,6 @@ typedef enum {
 typedef struct {
   Frame *fbuf[FRAMES_PER_TOC_ENTRY_]; ///< The frames buffered.
   size_t idx;                         ///< Points to currently open frame.
-  size_t frames_written; ///< Number of frames written from buffer to file.
 } FrameBuffer;
 
 /**

contrib/plugins/bap-tracing/tracing.c

@@ -97,9 +97,19 @@ static GPtrArray *registers_init(void) {
   return registers->len ? g_steal_pointer(&registers) : NULL;
 }
 
+static void write_toc_entry(FrameBuffer *fbuf) {
+  g_rw_lock_writer_lock(&state.file_lock);
+  g_rw_lock_writer_lock(&state.toc_entries_offsets_lock);
+  frame_buffer_flush_to_file(fbuf, state.file);
+  uint64_t next_toc_entry = ftell(state.file);
+  g_array_append_val(state.toc_entries_offsets, next_toc_entry);
+  g_rw_lock_writer_unlock(&state.toc_entries_offsets_lock);
+  g_rw_lock_writer_unlock(&state.file_lock);
+}
+
 static void log_insn_reg_access(unsigned int vcpu_index, void *udata) {
   g_rw_lock_reader_lock(&state.vcpus_array_lock);
-  g_rw_lock_reader_lock(&state.frame_buffer_lock);
+  g_rw_lock_writer_lock(&state.frame_buffer_lock);
 
   FrameBuffer *fbuf = g_ptr_array_index(state.frame_buffer, vcpu_index);
   VCPU *vcpu = g_ptr_array_index(state.vcpus, vcpu_index);
@@ -113,17 +123,15 @@ static void log_insn_reg_access(unsigned int vcpu_index, void *udata) {
   }
 
   if (frame_buffer_is_full(fbuf)) {
-    g_rw_lock_writer_lock(&state.file_lock);
-    frame_buffer_flush_to_file(fbuf, state.file);
-    g_rw_lock_writer_unlock(&state.file_lock);
+    write_toc_entry(fbuf);
   }
 
   // Open new one.
   Instruction *insn = udata;
   add_new_insn_frame(vcpu, vcpu_index, fbuf, insn);
   add_pre_reg_state(vcpu, vcpu_index, current_regs, fbuf);
 
-  g_rw_lock_reader_unlock(&state.frame_buffer_lock);
+  g_rw_lock_writer_unlock(&state.frame_buffer_lock);
   g_rw_lock_reader_unlock(&state.vcpus_array_lock);
 }
 
@@ -228,9 +236,11 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
 
   const char *target_path = "/tmp/test.trace";
   state.frame_buffer = g_ptr_array_new();
+  state.toc_entries_offsets = g_array_new(false, true, sizeof(uint64_t));
   state.vcpus = g_ptr_array_new();
   state.file = fopen(target_path, "wb");
-  if (!(state.frame_buffer || state.vcpus || state.file)) {
+  if (!(state.frame_buffer || state.vcpus || state.file ||
+        !state.toc_entries_offsets)) {
     return 1;
   }
   for (size_t i = 0; i < argc; ++i) {
@@ -242,6 +252,8 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
   }
   // write_meta(argv, envp, target_argv, target_envp);
 
+  g_array_append_val(state.toc_entries_offsets, offset_toc_start);
+
   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);

contrib/plugins/bap-tracing/tracing.h

@@ -134,6 +134,9 @@ typedef struct {
   GRWLock frame_buffer_lock;
   GPtrArray /*<FrameBuffer>*/ *frame_buffer; ///< Indexed by vcpu id
 
+  GRWLock toc_entries_offsets_lock;
+  GArray /*<uint64_t>*/ *toc_entries_offsets;
+
   GRWLock file_lock;
   FILE *file;
 } TraceState;