contrib/plugins/hotblocks.c

   1 /*
   2  * Copyright (C) 2019, Alex Bennée <alex.bennee@linaro.org>
   3  *
   4  * License: GNU GPL, version 2 or later.
   5  *   See the COPYING file in the top-level directory.
   6  */
   7 #include <inttypes.h>
   8 #include <assert.h>
   9 #include <stdlib.h>
  10 #include <inttypes.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13 #include <stdio.h>
  14 #include <glib.h>
  15
  16 #include <qemu-plugin.h>
  17
  18 QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
  19
  20 static bool do_inline;
  21
  22 /* Plugins need to take care of their own locking */
  23 static GMutex lock;
  24 static GHashTable *hotblocks;
  25 static guint64 limit = 20;
  26
  27 /*
  28  * Counting Structure
  29  *
  30  * The internals of the TCG are not exposed to plugins so we can only
  31  * get the starting PC for each block. We cheat this slightly by
  32  * xor'ing the number of instructions to the hash to help
  33  * differentiate.
  34  */
  35 typedef struct {
  36     uint64_t start_addr;
  37     uint64_t exec_count;
  38     int      trans_count;
  39     unsigned long insns;
  40 } ExecCount;
  41
  42 static gint cmp_exec_count(gconstpointer a, gconstpointer b)
  43 {
  44     ExecCount *ea = (ExecCount *) a;
  45     ExecCount *eb = (ExecCount *) b;
  46     return ea->exec_count > eb->exec_count ? -1 : 1;
  47 }
  48
  49 static void plugin_exit(qemu_plugin_id_t id, void *p)
  50 {
  51     g_autoptr(GString) report = g_string_new("collected ");
  52     GList *counts, *it;
  53     int i;
  54
  55     g_mutex_lock(&lock);
  56     g_string_append_printf(report, "%d entries in the hash table\n",
  57                            g_hash_table_size(hotblocks));
  58     counts = g_hash_table_get_values(hotblocks);
  59     it = g_list_sort(counts, cmp_exec_count);
  60
  61     if (it) {
  62         g_string_append_printf(report, "pc, tcount, icount, ecount\n");
  63
  64         for (i = 0; i < limit && it->next; i++, it = it->next) {
  65             ExecCount *rec = (ExecCount *) it->data;
  66             g_string_append_printf(report, "0x%016"PRIx64", %d, %ld, %"PRId64"\n",
  67                                    rec->start_addr, rec->trans_count,
  68                                    rec->insns, rec->exec_count);
  69         }
  70
  71         g_list_free(it);
  72         g_mutex_unlock(&lock);
  73     }
  74
  75     qemu_plugin_outs(report->str);
  76 }
  77
  78 static void plugin_init(void)
  79 {
  80     hotblocks = g_hash_table_new(NULL, g_direct_equal);
  81 }
  82
  83 static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
  84 {
  85     ExecCount *cnt;
  86     uint64_t hash = (uint64_t) udata;
  87
  88     g_mutex_lock(&lock);
  89     cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
  90     /* should always succeed */
  91     g_assert(cnt);
  92     cnt->exec_count++;
  93     g_mutex_unlock(&lock);
  94 }
  95
  96 /*
  97  * When do_inline we ask the plugin to increment the counter for us.
  98  * Otherwise a helper is inserted which calls the vcpu_tb_exec
  99  * callback.
 100  */
 101 static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
 102 {
 103     ExecCount *cnt;
 104     uint64_t pc = qemu_plugin_tb_vaddr(tb);
 105     size_t insns = qemu_plugin_tb_n_insns(tb);
 106     uint64_t hash = pc ^ insns;
 107
 108     g_mutex_lock(&lock);
 109     cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
 110     if (cnt) {
 111         cnt->trans_count++;
 112     } else {
 113         cnt = g_new0(ExecCount, 1);
 114         cnt->start_addr = pc;
 115         cnt->trans_count = 1;
 116         cnt->insns = insns;
 117         g_hash_table_insert(hotblocks, (gpointer) hash, (gpointer) cnt);
 118     }
 119
 120     g_mutex_unlock(&lock);
 121
 122     if (do_inline) {
 123         qemu_plugin_register_vcpu_tb_exec_inline(tb, QEMU_PLUGIN_INLINE_ADD_U64,
 124                                                  &cnt->exec_count, 1);
 125     } else {
 126         qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
 127                                              QEMU_PLUGIN_CB_NO_REGS,
 128                                              (void *)hash);
 129     }
 130 }
 131
 132 QEMU_PLUGIN_EXPORT
 133 int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
 134                         int argc, char **argv)
 135 {
 136     for (int i = 0; i < argc; i++) {
 137         char *opt = argv[i];
 138         g_autofree char **tokens = g_strsplit(opt, "=", 2);
 139         if (g_strcmp0(tokens[0], "inline") == 0) {
 140             if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &do_inline)) {
 141                 fprintf(stderr, "boolean argument parsing failed: %s\n", opt);
 142                 return -1;
 143             }
 144         } else {
 145             fprintf(stderr, "option parsing failed: %s\n", opt);
 146             return -1;
 147         }
 148     }
 149
 150     plugin_init();
 151
 152     qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
 153     qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
 154     return 0;
 155 }