diff options
Diffstat (limited to 'plugins/loader.c')
| -rw-r--r-- | plugins/loader.c | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/plugins/loader.c b/plugins/loader.c new file mode 100644 index 0000000000..eaedff577c --- /dev/null +++ b/plugins/loader.c @@ -0,0 +1,362 @@ +/* + * 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/option.h" +#include "qemu/rcu_queue.h" +#include "qemu/qht.h" +#include "qemu/bitmap.h" +#include "qemu/xxhash.h" +#include "qemu/plugin.h" +#include "hw/core/cpu.h" +#include "cpu.h" +#include "exec/exec-all.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, 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; + + 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 (strcmp(name, "arg") == 0) { + if (arg->curr == NULL) { + error_setg(errp, "missing earlier '-plugin file=' option"); + return 1; + } + p = arg->curr; + p->argc++; + p->argv = g_realloc_n(p->argv, p->argc, sizeof(char *)); + p->argv[p->argc - 1] = g_strdup(value); + } else { + error_setg(errp, "-plugin: unexpected parameter '%s'; ignored", name); + } + 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); +} + +static int plugin_load(struct qemu_plugin_desc *desc) +{ + 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_report("%s: %s", __func__, g_module_error()); + goto err_dlopen; + } + + if (!g_module_symbol(ctx->handle, "qemu_plugin_install", &sym)) { + error_report("%s: %s", __func__, 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_report("%s: %s: qemu_plugin_install is NULL", + __func__, desc->path); + 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, desc->argc, desc->argv); + ctx->installing = false; + if (rc) { + error_report("%s: qemu_plugin_install returned error code %d", + __func__, 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: + 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) +{ + struct qemu_plugin_desc *desc, *next; + + QTAILQ_FOREACH_SAFE(desc, head, entry, next) { + int err; + + err = plugin_load(desc); + 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; + + qemu_rec_mutex_lock(&plugin.lock); + ctx = plugin_id_to_ctx_locked(id); + if (ctx->uninstalling || (reset && ctx->resetting)) { + qemu_rec_mutex_unlock(&plugin.lock); + return; + } + ctx->resetting = reset; + ctx->uninstalling = !reset; + qemu_rec_mutex_unlock(&plugin.lock); + + 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); + } +} |