/*
* QEMU Plugin Core Loader Code
*
* This is the code responsible for loading and unloading the plugins.
* Aside from the basic housekeeping tasks we also need to ensure any
* generated code is flushed when we remove a plugin so we cannot end
* up calling and unloaded helper function.
*
* Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
* Copyright (C) 2019, Linaro
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qemu/error-report.h"
#include "qemu/config-file.h"
#include "qapi/error.h"
#include "qemu/lockable.h"
#include "qemu/option.h"
#include "qemu/rcu_queue.h"
#include "qemu/qht.h"
#include "qemu/bitmap.h"
#include "qemu/cacheinfo.h"
#include "qemu/xxhash.h"
#include "qemu/plugin.h"
#include "qemu/memalign.h"
#include "hw/core/cpu.h"
#include "exec/exec-all.h"
#ifndef CONFIG_USER_ONLY
#include "hw/boards.h"
#endif
#include "qemu/compiler.h"
#include "plugin.h"
/*
* For convenience we use a bitmap for plugin.mask, but really all we need is a
* u32, which is what we store in TranslationBlock.
*/
QEMU_BUILD_BUG_ON(QEMU_PLUGIN_EV_MAX > 32);
struct qemu_plugin_desc {
char *path;
char **argv;
QTAILQ_ENTRY(qemu_plugin_desc) entry;
int argc;
};
struct qemu_plugin_parse_arg {
QemuPluginList *head;
struct qemu_plugin_desc *curr;
};
QemuOptsList qemu_plugin_opts = {
.name = "plugin",
.implied_opt_name = "file",
.head = QTAILQ_HEAD_INITIALIZER(qemu_plugin_opts.head),
.desc = {
/* do our own parsing to support multiple plugins */
{ /* end of list */ }
},
};
typedef int (*qemu_plugin_install_func_t)(qemu_plugin_id_t, const qemu_info_t *, int, char **);
extern struct qemu_plugin_state plugin;
void qemu_plugin_add_dyn_cb_arr(GArray *arr)
{
uint32_t hash = qemu_xxhash2((uint64_t)(uintptr_t)arr);
bool inserted;
inserted = qht_insert(&plugin.dyn_cb_arr_ht, arr, hash, NULL);
g_assert(inserted);
}
static struct qemu_plugin_desc *plugin_find_desc(QemuPluginList *head,
const char *path)
{
struct qemu_plugin_desc *desc;
QTAILQ_FOREACH(desc, head, entry) {
if (strcmp(desc->path, path) == 0) {
return desc;
}
}
return NULL;
}
static int plugin_add(void *opaque, const char *name, const char *value,
Error **errp)
{
struct qemu_plugin_parse_arg *arg = opaque;
struct qemu_plugin_desc *p;
bool is_on;
char *fullarg;
if (strcmp(name, "file") == 0) {
if (strcmp(value, "") == 0) {
error_setg(errp, "requires a non-empty argument");
return 1;
}
p = plugin_find_desc(arg->head, value);
if (p == NULL) {
p = g_new0(struct qemu_plugin_desc, 1);
p->path = g_strdup(value);
QTAILQ_INSERT_TAIL(arg->head, p, entry);
}
arg->curr = p;
} else {
if (arg->curr == NULL) {
error_setg(errp, "missing earlier '-plugin file=' option");
return 1;
}
if (g_strcmp0(name, "arg") == 0 &&
!qapi_bool_parse(name, value, &is_on, NULL)) {
if (strchr(value, '=') == NULL) {
/* Will treat arg="argname" as "argname=on" */
fullarg = g_strdup_printf("%s=%s", value, "on");
} else {
fullarg = g_strdup_printf("%s", value);
}
warn_report("using 'arg=%s' is deprecated", value);
error_printf("Please use '%s' directly\n", fullarg);
} else {
fullarg = g_strdup_printf("%s=%s", name, value);
}
p = arg->curr;
p->argc++;
p->argv = g_realloc_n(p->argv, p->argc, sizeof(char *));
p->argv[p->argc - 1] = fullarg;
}
return 0;
}
void qemu_plugin_opt_parse(const char *optarg, QemuPluginList *head)
{
struct qemu_plugin_parse_arg arg;
QemuOpts *opts;
opts = qemu_opts_parse_noisily(qemu_find_opts("plugin"), optarg, true);
if (opts == NULL) {
exit(1);
}
arg.head = head;
arg.curr = NULL;
qemu_opt_foreach(opts, plugin_add, &arg, &error_fatal);
qemu_opts_del(opts);
}
/*
* From: https://en.wikipedia.org/wiki/Xorshift
* This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
* guaranteed to be >= INT_MAX).
*/
static uint64_t xorshift64star(uint64_t x)
{
x ^= x >> 12; /* a */
x ^= x << 25; /* b */
x ^= x >> 27; /* c */
return x * UINT64_C(2685821657736338717);
}
/*
* Disable CFI checks.
* The install and version functions have been loaded from an external library
* so we do not have type information
*/
QEMU_DISABLE_CFI
static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info, Error **errp)
{
qemu_plugin_install_func_t install;
struct qemu_plugin_ctx *ctx;
gpointer sym;
int rc;
ctx = qemu_memalign(qemu_dcache_linesize, sizeof(*ctx));
memset(ctx, 0, sizeof(*ctx));
ctx->desc = desc;
ctx->handle = g_module_open(desc->path, G_MODULE_BIND_LOCAL);
if (ctx->handle == NULL) {
error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
goto err_dlopen;
}
if (!g_module_symbol(ctx->handle, "qemu_plugin_install", &sym)) {
error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
goto err_symbol;
}
install = (qemu_plugin_install_func_t) sym;
/* symbol was found; it could be NULL though */
if (install == NULL) {
error_setg(errp, "Could not load plugin %s: qemu_plugin_install is NULL",
desc->path);
goto err_symbol;
}
if (!g_module_symbol(ctx->handle, "qemu_plugin_version", &sym)) {
error_setg(errp, "Could not load plugin %s: plugin does not declare API version %s",
desc->path, g_module_error());
goto err_symbol;
} else {
int version = *(int *)sym;
if (version < QEMU_PLUGIN_MIN_VERSION) {
error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
"this QEMU supports only a minimum version of %d",
desc->path, version, QEMU_PLUGIN_MIN_VERSION);
goto err_symbol;
} else if (version > QEMU_PLUGIN_VERSION) {
error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
"this QEMU supports only up to version %d",
desc->path, version, QEMU_PLUGIN_VERSION);
goto err_symbol;
}
}
qemu_rec_mutex_lock(&plugin.lock);
/* find an unused random id with &ctx as the seed */
ctx->id = (uint64_t)(uintptr_t)ctx;
for (;;) {
void *existing;
ctx->id = xorshift64star(ctx->id);
existing = g_hash_table_lookup(plugin.id_ht, &ctx->id);
if (likely(existing == NULL)) {
bool success;
success = g_hash_table_insert(plugin.id_ht, &ctx->id, &ctx->id);
g_assert(success);
break;
}
}
QTAILQ_INSERT_TAIL(&plugin.ctxs, ctx, entry);
ctx->installing = true;
rc = install(ctx->id, info, desc->argc, desc->argv);
ctx->installing = false;
if (rc) {
error_setg(errp, "Could not load plugin %s: qemu_plugin_install returned error code %d",
desc->path, rc);
/*
* we cannot rely on the plugin doing its own cleanup, so
* call a full uninstall if the plugin did not yet call it.
*/
if (!ctx->uninstalling) {
plugin_reset_uninstall(ctx->id, NULL, false);
}
}
qemu_rec_mutex_unlock(&plugin.lock);
return rc;
err_symbol:
g_module_close(ctx->handle);
err_dlopen:
qemu_vfree(ctx);
return 1;
}
/* call after having removed @desc from the list */
static void plugin_desc_free(struct qemu_plugin_desc *desc)
{
int i;
for (i = 0; i < desc->argc; i++) {
g_free(desc->argv[i]);
}
g_free(desc->argv);
g_free(desc->path);
g_free(desc);
}
/**
* qemu_plugin_load_list - load a list of plugins
* @head: head of the list of descriptors of the plugins to be loaded
*
* Returns 0 if all plugins in the list are installed, !0 otherwise.
*
* Note: the descriptor of each successfully installed plugin is removed
* from the list given by @head.
*/
int qemu_plugin_load_list(QemuPluginList *head, Error **errp)
{
struct qemu_plugin_desc *desc, *next;
g_autofree qemu_info_t *info = g_new0(qemu_info_t, 1);
info->target_name = TARGET_NAME;
info->version.min = QEMU_PLUGIN_MIN_VERSION;
info->version.cur = QEMU_PLUGIN_VERSION;
#ifndef CONFIG_USER_ONLY
MachineState *ms = MACHINE(qdev_get_machine());
info->system_emulation = true;
info->system.smp_vcpus = ms->smp.cpus;
info->system.max_vcpus = ms->smp.max_cpus;
#else
info->system_emulation = false;
#endif
QTAILQ_FOREACH_SAFE(desc, head, entry, next) {
int err;
err = plugin_load(desc, info, errp);
if (err) {
return err;
}
QTAILQ_REMOVE(head, desc, entry);
}
return 0;
}
struct qemu_plugin_reset_data {
struct qemu_plugin_ctx *ctx;
qemu_plugin_simple_cb_t cb;
bool reset;
};
static void plugin_reset_destroy__locked(struct qemu_plugin_reset_data *data)
{
struct qemu_plugin_ctx *ctx = data->ctx;
enum qemu_plugin_event ev;
bool success;
/*
* After updating the subscription lists there is no need to wait for an RCU
* grace period to elapse, because right now we either are in a "safe async"
* work environment (i.e. all vCPUs are asleep), or no vCPUs have yet been
* created.
*/
for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
plugin_unregister_cb__locked(ctx, ev);
}
if (data->reset) {
g_assert(ctx->resetting);
if (data->cb) {
data->cb(ctx->id);
}
ctx->resetting = false;
g_free(data);
return;
}
g_assert(ctx->uninstalling);
/* we cannot dlclose if we are going to return to plugin code */
if (ctx->installing) {
error_report("Calling qemu_plugin_uninstall from the install function "
"is a bug. Instead, return !0 from the install function.");
abort();
}
success = g_hash_table_remove(plugin.id_ht, &ctx->id);
g_assert(success);
QTAILQ_REMOVE(&plugin.ctxs, ctx, entry);
if (data->cb) {
data->cb(ctx->id);
}
if (!g_module_close(ctx->handle)) {
warn_report("%s: %s", __func__, g_module_error());
}
plugin_desc_free(ctx->desc);
qemu_vfree(ctx);
g_free(data);
}
static void plugin_reset_destroy(struct qemu_plugin_reset_data *data)
{
qemu_rec_mutex_lock(&plugin.lock);
plugin_reset_destroy__locked(data);
qemu_rec_mutex_lock(&plugin.lock);
}
static void plugin_flush_destroy(CPUState *cpu, run_on_cpu_data arg)
{
struct qemu_plugin_reset_data *data = arg.host_ptr;
g_assert(cpu_in_exclusive_context(cpu));
tb_flush(cpu);
plugin_reset_destroy(data);
}
void plugin_reset_uninstall(qemu_plugin_id_t id,
qemu_plugin_simple_cb_t cb,
bool reset)
{
struct qemu_plugin_reset_data *data;
struct qemu_plugin_ctx *ctx;
WITH_QEMU_LOCK_GUARD(&plugin.lock) {
ctx = plugin_id_to_ctx_locked(id);
if (ctx->uninstalling || (reset && ctx->resetting)) {
return;
}
ctx->resetting = reset;
ctx->uninstalling = !reset;
}
data = g_new(struct qemu_plugin_reset_data, 1);
data->ctx = ctx;
data->cb = cb;
data->reset = reset;
/*
* Only flush the code cache if the vCPUs have been created. If so,
* current_cpu must be non-NULL.
*/
if (current_cpu) {
async_safe_run_on_cpu(current_cpu, plugin_flush_destroy,
RUN_ON_CPU_HOST_PTR(data));
} else {
/*
* If current_cpu isn't set, then we don't have yet any vCPU threads
* and we therefore can remove the callbacks synchronously.
*/
plugin_reset_destroy(data);
}
}
