summaryrefslogtreecommitdiffstats
path: root/plugins/loader.c
blob: 88c30bde2d6aa4c18f86b2853129a8304598abdb (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
/*
 * 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);
    }
}