xref: /openbmc/qemu/contrib/plugins/hotblocks.c (revision 4921d0a7)
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     struct qemu_plugin_scoreboard *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     uint64_t count_a =
47         qemu_plugin_u64_sum(qemu_plugin_scoreboard_u64(ea->exec_count));
48     uint64_t count_b =
49         qemu_plugin_u64_sum(qemu_plugin_scoreboard_u64(eb->exec_count));
50     return count_a > count_b ? -1 : 1;
51 }
52 
53 static void exec_count_free(gpointer key, gpointer value, gpointer user_data)
54 {
55     ExecCount *cnt = value;
56     qemu_plugin_scoreboard_free(cnt->exec_count);
57 }
58 
59 static void plugin_exit(qemu_plugin_id_t id, void *p)
60 {
61     g_autoptr(GString) report = g_string_new("collected ");
62     GList *counts, *it;
63     int i;
64 
65     g_string_append_printf(report, "%d entries in the hash table\n",
66                            g_hash_table_size(hotblocks));
67     counts = g_hash_table_get_values(hotblocks);
68     it = g_list_sort(counts, cmp_exec_count);
69 
70     if (it) {
71         g_string_append_printf(report, "pc, tcount, icount, ecount\n");
72 
73         for (i = 0; i < limit && it->next; i++, it = it->next) {
74             ExecCount *rec = (ExecCount *) it->data;
75             g_string_append_printf(
76                 report, "0x%016"PRIx64", %d, %ld, %"PRId64"\n",
77                 rec->start_addr, rec->trans_count,
78                 rec->insns,
79                 qemu_plugin_u64_sum(
80                     qemu_plugin_scoreboard_u64(rec->exec_count)));
81         }
82 
83         g_list_free(it);
84     }
85 
86     qemu_plugin_outs(report->str);
87 
88     g_hash_table_foreach(hotblocks, exec_count_free, NULL);
89     g_hash_table_destroy(hotblocks);
90 }
91 
92 static void plugin_init(void)
93 {
94     hotblocks = g_hash_table_new(NULL, g_direct_equal);
95 }
96 
97 static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
98 {
99     ExecCount *cnt = (ExecCount *)udata;
100     qemu_plugin_u64_add(qemu_plugin_scoreboard_u64(cnt->exec_count),
101                         cpu_index, 1);
102 }
103 
104 /*
105  * When do_inline we ask the plugin to increment the counter for us.
106  * Otherwise a helper is inserted which calls the vcpu_tb_exec
107  * callback.
108  */
109 static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
110 {
111     ExecCount *cnt;
112     uint64_t pc = qemu_plugin_tb_vaddr(tb);
113     size_t insns = qemu_plugin_tb_n_insns(tb);
114     uint64_t hash = pc ^ insns;
115 
116     g_mutex_lock(&lock);
117     cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
118     if (cnt) {
119         cnt->trans_count++;
120     } else {
121         cnt = g_new0(ExecCount, 1);
122         cnt->start_addr = pc;
123         cnt->trans_count = 1;
124         cnt->insns = insns;
125         cnt->exec_count = qemu_plugin_scoreboard_new(sizeof(uint64_t));
126         g_hash_table_insert(hotblocks, (gpointer) hash, (gpointer) cnt);
127     }
128 
129     g_mutex_unlock(&lock);
130 
131     if (do_inline) {
132         qemu_plugin_register_vcpu_tb_exec_inline_per_vcpu(
133             tb, QEMU_PLUGIN_INLINE_ADD_U64,
134             qemu_plugin_scoreboard_u64(cnt->exec_count), 1);
135     } else {
136         qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
137                                              QEMU_PLUGIN_CB_NO_REGS,
138                                              (void *)cnt);
139     }
140 }
141 
142 QEMU_PLUGIN_EXPORT
143 int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
144                         int argc, char **argv)
145 {
146     for (int i = 0; i < argc; i++) {
147         char *opt = argv[i];
148         g_auto(GStrv) tokens = g_strsplit(opt, "=", 2);
149         if (g_strcmp0(tokens[0], "inline") == 0) {
150             if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &do_inline)) {
151                 fprintf(stderr, "boolean argument parsing failed: %s\n", opt);
152                 return -1;
153             }
154         } else {
155             fprintf(stderr, "option parsing failed: %s\n", opt);
156             return -1;
157         }
158     }
159 
160     plugin_init();
161 
162     qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
163     qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
164     return 0;
165 }
166