qemu/contrib/plugins/hotblocks.c
Alex Bennée c17a386b6a plugins: move the more involved plugins to contrib
We have an exploding complexity problem in the testing so lets just
move the more involved plugins into contrib. tests/plugins still exist
for the basic plugins that exercise the API. We restore the old
pre-meson style Makefile for contrib as it also doubles as a guide for
out-of-tree plugin builds.

While we are at it add some examples to the documentation and a
specific plugins build target.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200909112742.25730-11-alex.bennee@linaro.org>
2020-09-10 10:47:03 +01:00

146 lines
3.9 KiB
C

/*
* Copyright (C) 2019, Alex Bennée <alex.bennee@linaro.org>
*
* 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 bool do_inline;
/* Plugins need to take care of their own locking */
static GMutex lock;
static GHashTable *hotblocks;
static guint64 limit = 20;
/*
* Counting Structure
*
* The internals of the TCG are not exposed to plugins so we can only
* get the starting PC for each block. We cheat this slightly by
* xor'ing the number of instructions to the hash to help
* differentiate.
*/
typedef struct {
uint64_t start_addr;
uint64_t exec_count;
int trans_count;
unsigned long insns;
} ExecCount;
static gint cmp_exec_count(gconstpointer a, gconstpointer b)
{
ExecCount *ea = (ExecCount *) a;
ExecCount *eb = (ExecCount *) b;
return ea->exec_count > eb->exec_count ? -1 : 1;
}
static void plugin_exit(qemu_plugin_id_t id, void *p)
{
g_autoptr(GString) report = g_string_new("collected ");
GList *counts, *it;
int i;
g_mutex_lock(&lock);
g_string_append_printf(report, "%d entries in the hash table\n",
g_hash_table_size(hotblocks));
counts = g_hash_table_get_values(hotblocks);
it = g_list_sort(counts, cmp_exec_count);
if (it) {
g_string_append_printf(report, "pc, tcount, icount, ecount\n");
for (i = 0; i < limit && it->next; i++, it = it->next) {
ExecCount *rec = (ExecCount *) it->data;
g_string_append_printf(report, "%#016"PRIx64", %d, %ld, %"PRId64"\n",
rec->start_addr, rec->trans_count,
rec->insns, rec->exec_count);
}
g_list_free(it);
g_mutex_unlock(&lock);
}
qemu_plugin_outs(report->str);
}
static void plugin_init(void)
{
hotblocks = g_hash_table_new(NULL, g_direct_equal);
}
static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
{
ExecCount *cnt;
uint64_t hash = (uint64_t) udata;
g_mutex_lock(&lock);
cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
/* should always succeed */
g_assert(cnt);
cnt->exec_count++;
g_mutex_unlock(&lock);
}
/*
* When do_inline we ask the plugin to increment the counter for us.
* Otherwise a helper is inserted which calls the vcpu_tb_exec
* callback.
*/
static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
{
ExecCount *cnt;
uint64_t pc = qemu_plugin_tb_vaddr(tb);
unsigned long insns = qemu_plugin_tb_n_insns(tb);
uint64_t hash = pc ^ insns;
g_mutex_lock(&lock);
cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
if (cnt) {
cnt->trans_count++;
} else {
cnt = g_new0(ExecCount, 1);
cnt->start_addr = pc;
cnt->trans_count = 1;
cnt->insns = insns;
g_hash_table_insert(hotblocks, (gpointer) hash, (gpointer) cnt);
}
g_mutex_unlock(&lock);
if (do_inline) {
qemu_plugin_register_vcpu_tb_exec_inline(tb, QEMU_PLUGIN_INLINE_ADD_U64,
&cnt->exec_count, 1);
} else {
qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
QEMU_PLUGIN_CB_NO_REGS,
(void *)hash);
}
}
QEMU_PLUGIN_EXPORT
int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
int argc, char **argv)
{
if (argc && strcmp(argv[0], "inline") == 0) {
do_inline = true;
}
plugin_init();
qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
return 0;
}