contrib/plugins: add a drcov plugin

This patch adds the ability to generate files in drcov format. Primary
goal this script is to have coverage logfiles thatwork in Lighthouse.

Signed-off-by: Ivanov Arkady <arkadiy.ivanov@ispras.ru>
Message-Id: <163491884553.304355.13246023070235438959.stgit@pc-System-Product-Name>
[AJB: use g_ptr_array instead of slist]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220204204335.1689602-23-alex.bennee@linaro.org>

contrib/plugins/Makefile

@@ -20,6 +20,7 @@ NAMES += howvec
 NAMES += lockstep
 NAMES += hwprofile
 NAMES += cache
+NAMES += drcov
 
 SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
 

contrib/plugins/drcov.c

@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2021, Ivanov Arkady <arkadiy.ivanov@ispras.ru>
+ *
+ * Drcov - a DynamoRIO-based tool that collects coverage information
+ * from a binary. Primary goal this script is to have coverage log
+ * files that work in Lighthouse.
+ *
+ * License: GNU GPL, version 2 or later.
+ *   See the COPYING file in the top-level directory.
+ */
+
+#include <inttypes.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <glib.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+static char header[] = "DRCOV VERSION: 2\n"
+                "DRCOV FLAVOR: drcov-64\n"
+                "Module Table: version 2, count 1\n"
+                "Columns: id, base, end, entry, path\n";
+
+static FILE *fp;
+static const char *file_name = "file.drcov.trace";
+static GMutex lock;
+
+typedef struct {
+    uint32_t start;
+    uint16_t size;
+    uint16_t mod_id;
+    bool     exec;
+} bb_entry_t;
+
+/* Translated blocks */
+static GPtrArray *blocks;
+
+static void printf_header(unsigned long count)
+{
+    fprintf(fp, "%s", header);
+    const char *path = qemu_plugin_path_to_binary();
+    uint64_t start_code = qemu_plugin_start_code();
+    uint64_t end_code = qemu_plugin_end_code();
+    uint64_t entry = qemu_plugin_entry_code();
+    fprintf(fp, "0, 0x%lx, 0x%lx, 0x%lx, %s\n",
+            start_code, end_code, entry, path);
+    fprintf(fp, "BB Table: %ld bbs\n", count);
+}
+
+static void printf_char_array32(uint32_t data)
+{
+    const uint8_t *bytes = (const uint8_t *)(&data);
+    fwrite(bytes, sizeof(char), sizeof(data), fp);
+}
+
+static void printf_char_array16(uint16_t data)
+{
+    const uint8_t *bytes = (const uint8_t *)(&data);
+    fwrite(bytes, sizeof(char), sizeof(data), fp);
+}
+
+
+static void printf_el(gpointer data, gpointer user_data)
+{
+    bb_entry_t *bb = (bb_entry_t *)data;
+    if (bb->exec) {
+        printf_char_array32(bb->start);
+        printf_char_array16(bb->size);
+        printf_char_array16(bb->mod_id);
+    }
+    g_free(bb);
+}
+
+static void count_block(gpointer data, gpointer user_data)
+{
+    unsigned long *count = (unsigned long *) user_data;
+    bb_entry_t *bb = (bb_entry_t *)data;
+    if (bb->exec) {
+        *count = *count + 1;
+    }
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+    unsigned long count = 0;
+    g_mutex_lock(&lock);
+    g_ptr_array_foreach(blocks, count_block, &count);
+
+    /* Print function */
+    printf_header(count);
+    g_ptr_array_foreach(blocks, printf_el, NULL);
+
+    /* Clear */
+    g_ptr_array_free(blocks, true);
+
+    fclose(fp);
+
+    g_mutex_unlock(&lock);
+}
+
+static void plugin_init(void)
+{
+    fp = fopen(file_name, "wb");
+    blocks = g_ptr_array_sized_new(128);
+}
+
+static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
+{
+    bb_entry_t *bb = (bb_entry_t *) udata;
+
+    g_mutex_lock(&lock);
+    bb->exec = true;
+    g_mutex_unlock(&lock);
+}
+
+static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+    uint64_t pc = qemu_plugin_tb_vaddr(tb);
+    size_t n = qemu_plugin_tb_n_insns(tb);
+
+    g_mutex_lock(&lock);
+
+    bb_entry_t *bb = g_new0(bb_entry_t, 1);
+    for (int i = 0; i < n; i++) {
+        bb->size += qemu_plugin_insn_size(qemu_plugin_tb_get_insn(tb, i));
+    }
+
+    bb->start = pc;
+    bb->mod_id = 0;
+    bb->exec = false;
+    g_ptr_array_add(blocks, bb);
+
+    g_mutex_unlock(&lock);
+    qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
+                                         QEMU_PLUGIN_CB_NO_REGS,
+                                         (void *)bb);
+
+}
+
+QEMU_PLUGIN_EXPORT
+int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
+                        int argc, char **argv)
+{
+    for (int i = 0; i < argc; i++) {
+        g_autofree char **tokens = g_strsplit(argv[i], "=", 2);
+        if (g_strcmp0(tokens[0], "filename") == 0) {
+            file_name = g_strdup(tokens[1]);
+        }
+    }
+
+    plugin_init();
+
+    qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
+    qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+
+    return 0;
+}