qemu

core.c (15605B)

---

 /*
  * QEMU Plugin Core code
  *
  * This is the core code that deals with injecting instrumentation into the code
  *
  * 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/xxhash.h"
 #include "qemu/rcu.h"
 #include "hw/core/cpu.h"
 #include "exec/cpu-common.h"
 
 #include "exec/exec-all.h"
 #include "exec/helper-proto.h"
 #include "tcg/tcg.h"
 #include "tcg/tcg-op.h"
 #include "plugin.h"
 #include "qemu/compiler.h"
 
 struct qemu_plugin_cb {
     struct qemu_plugin_ctx *ctx;
     union qemu_plugin_cb_sig f;
     void *udata;
     QLIST_ENTRY(qemu_plugin_cb) entry;
 };
 
 struct qemu_plugin_state plugin;
 
 struct qemu_plugin_ctx *plugin_id_to_ctx_locked(qemu_plugin_id_t id)
 {
     struct qemu_plugin_ctx *ctx;
     qemu_plugin_id_t *id_p;
 
     id_p = g_hash_table_lookup(plugin.id_ht, &id);
     ctx = container_of(id_p, struct qemu_plugin_ctx, id);
     if (ctx == NULL) {
         error_report("plugin: invalid plugin id %" PRIu64, id);
         abort();
     }
     return ctx;
 }
 
 static void plugin_cpu_update__async(CPUState *cpu, run_on_cpu_data data)
 {
     bitmap_copy(cpu->plugin_mask, &data.host_ulong, QEMU_PLUGIN_EV_MAX);
     tcg_flush_jmp_cache(cpu);
 }
 
 static void plugin_cpu_update__locked(gpointer k, gpointer v, gpointer udata)
 {
     CPUState *cpu = container_of(k, CPUState, cpu_index);
     run_on_cpu_data mask = RUN_ON_CPU_HOST_ULONG(*plugin.mask);
 
     if (cpu->created) {
         async_run_on_cpu(cpu, plugin_cpu_update__async, mask);
     } else {
         plugin_cpu_update__async(cpu, mask);
     }
 }
 
 void plugin_unregister_cb__locked(struct qemu_plugin_ctx *ctx,
                                   enum qemu_plugin_event ev)
 {
     struct qemu_plugin_cb *cb = ctx->callbacks[ev];
 
     if (cb == NULL) {
         return;
     }
     QLIST_REMOVE_RCU(cb, entry);
     g_free(cb);
     ctx->callbacks[ev] = NULL;
     if (QLIST_EMPTY_RCU(&plugin.cb_lists[ev])) {
         clear_bit(ev, plugin.mask);
         g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked, NULL);
     }
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 static void plugin_vcpu_cb__simple(CPUState *cpu, enum qemu_plugin_event ev)
 {
     struct qemu_plugin_cb *cb, *next;
 
     switch (ev) {
     case QEMU_PLUGIN_EV_VCPU_INIT:
     case QEMU_PLUGIN_EV_VCPU_EXIT:
     case QEMU_PLUGIN_EV_VCPU_IDLE:
     case QEMU_PLUGIN_EV_VCPU_RESUME:
         /* iterate safely; plugins might uninstall themselves at any time */
         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
             qemu_plugin_vcpu_simple_cb_t func = cb->f.vcpu_simple;
 
             func(cb->ctx->id, cpu->cpu_index);
         }
         break;
     default:
         g_assert_not_reached();
     }
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 static void plugin_cb__simple(enum qemu_plugin_event ev)
 {
     struct qemu_plugin_cb *cb, *next;
 
     switch (ev) {
     case QEMU_PLUGIN_EV_FLUSH:
         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
             qemu_plugin_simple_cb_t func = cb->f.simple;
 
             func(cb->ctx->id);
         }
         break;
     default:
         g_assert_not_reached();
     }
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 static void plugin_cb__udata(enum qemu_plugin_event ev)
 {
     struct qemu_plugin_cb *cb, *next;
 
     switch (ev) {
     case QEMU_PLUGIN_EV_ATEXIT:
         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
             qemu_plugin_udata_cb_t func = cb->f.udata;
 
             func(cb->ctx->id, cb->udata);
         }
         break;
     default:
         g_assert_not_reached();
     }
 }
 
 static void
 do_plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
                       void *func, void *udata)
 {
     struct qemu_plugin_ctx *ctx;
 
     QEMU_LOCK_GUARD(&plugin.lock);
     ctx = plugin_id_to_ctx_locked(id);
     /* if the plugin is on its way out, ignore this request */
     if (unlikely(ctx->uninstalling)) {
         return;
     }
     if (func) {
         struct qemu_plugin_cb *cb = ctx->callbacks[ev];
 
         if (cb) {
             cb->f.generic = func;
             cb->udata = udata;
         } else {
             cb = g_new(struct qemu_plugin_cb, 1);
             cb->ctx = ctx;
             cb->f.generic = func;
             cb->udata = udata;
             ctx->callbacks[ev] = cb;
             QLIST_INSERT_HEAD_RCU(&plugin.cb_lists[ev], cb, entry);
             if (!test_bit(ev, plugin.mask)) {
                 set_bit(ev, plugin.mask);
                 g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked,
                                      NULL);
             }
         }
     } else {
         plugin_unregister_cb__locked(ctx, ev);
     }
 }
 
 void plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
                         void *func)
 {
     do_plugin_register_cb(id, ev, func, NULL);
 }
 
 void
 plugin_register_cb_udata(qemu_plugin_id_t id, enum qemu_plugin_event ev,
                          void *func, void *udata)
 {
     do_plugin_register_cb(id, ev, func, udata);
 }
 
 void qemu_plugin_vcpu_init_hook(CPUState *cpu)
 {
     bool success;
 
     qemu_rec_mutex_lock(&plugin.lock);
     plugin_cpu_update__locked(&cpu->cpu_index, NULL, NULL);
     success = g_hash_table_insert(plugin.cpu_ht, &cpu->cpu_index,
                                   &cpu->cpu_index);
     g_assert(success);
     qemu_rec_mutex_unlock(&plugin.lock);
 
     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_INIT);
 }
 
 void qemu_plugin_vcpu_exit_hook(CPUState *cpu)
 {
     bool success;
 
     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_EXIT);
 
     qemu_rec_mutex_lock(&plugin.lock);
     success = g_hash_table_remove(plugin.cpu_ht, &cpu->cpu_index);
     g_assert(success);
     qemu_rec_mutex_unlock(&plugin.lock);
 }
 
 struct plugin_for_each_args {
     struct qemu_plugin_ctx *ctx;
     qemu_plugin_vcpu_simple_cb_t cb;
 };
 
 static void plugin_vcpu_for_each(gpointer k, gpointer v, gpointer udata)
 {
     struct plugin_for_each_args *args = udata;
     int cpu_index = *(int *)k;
 
     args->cb(args->ctx->id, cpu_index);
 }
 
 void qemu_plugin_vcpu_for_each(qemu_plugin_id_t id,
                                qemu_plugin_vcpu_simple_cb_t cb)
 {
     struct plugin_for_each_args args;
 
     if (cb == NULL) {
         return;
     }
     qemu_rec_mutex_lock(&plugin.lock);
     args.ctx = plugin_id_to_ctx_locked(id);
     args.cb = cb;
     g_hash_table_foreach(plugin.cpu_ht, plugin_vcpu_for_each, &args);
     qemu_rec_mutex_unlock(&plugin.lock);
 }
 
 /* Allocate and return a callback record */
 static struct qemu_plugin_dyn_cb *plugin_get_dyn_cb(GArray **arr)
 {
     GArray *cbs = *arr;
 
     if (!cbs) {
         cbs = g_array_sized_new(false, false,
                                 sizeof(struct qemu_plugin_dyn_cb), 1);
         *arr = cbs;
     }
 
     g_array_set_size(cbs, cbs->len + 1);
     return &g_array_index(cbs, struct qemu_plugin_dyn_cb, cbs->len - 1);
 }
 
 void plugin_register_inline_op(GArray **arr,
                                enum qemu_plugin_mem_rw rw,
                                enum qemu_plugin_op op, void *ptr,
                                uint64_t imm)
 {
     struct qemu_plugin_dyn_cb *dyn_cb;
 
     dyn_cb = plugin_get_dyn_cb(arr);
     dyn_cb->userp = ptr;
     dyn_cb->type = PLUGIN_CB_INLINE;
     dyn_cb->rw = rw;
     dyn_cb->inline_insn.op = op;
     dyn_cb->inline_insn.imm = imm;
 }
 
 void plugin_register_dyn_cb__udata(GArray **arr,
                                    qemu_plugin_vcpu_udata_cb_t cb,
                                    enum qemu_plugin_cb_flags flags,
                                    void *udata)
 {
     struct qemu_plugin_dyn_cb *dyn_cb = plugin_get_dyn_cb(arr);
 
     dyn_cb->userp = udata;
     /* Note flags are discarded as unused. */
     dyn_cb->f.vcpu_udata = cb;
     dyn_cb->type = PLUGIN_CB_REGULAR;
 }
 
 void plugin_register_vcpu_mem_cb(GArray **arr,
                                  void *cb,
                                  enum qemu_plugin_cb_flags flags,
                                  enum qemu_plugin_mem_rw rw,
                                  void *udata)
 {
     struct qemu_plugin_dyn_cb *dyn_cb;
 
     dyn_cb = plugin_get_dyn_cb(arr);
     dyn_cb->userp = udata;
     /* Note flags are discarded as unused. */
     dyn_cb->type = PLUGIN_CB_REGULAR;
     dyn_cb->rw = rw;
     dyn_cb->f.generic = cb;
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 void qemu_plugin_tb_trans_cb(CPUState *cpu, struct qemu_plugin_tb *tb)
 {
     struct qemu_plugin_cb *cb, *next;
     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_TB_TRANS;
 
     /* no plugin_mask check here; caller should have checked */
 
     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
         qemu_plugin_vcpu_tb_trans_cb_t func = cb->f.vcpu_tb_trans;
 
         func(cb->ctx->id, tb);
     }
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 void
 qemu_plugin_vcpu_syscall(CPUState *cpu, int64_t num, uint64_t a1, uint64_t a2,
                          uint64_t a3, uint64_t a4, uint64_t a5,
                          uint64_t a6, uint64_t a7, uint64_t a8)
 {
     struct qemu_plugin_cb *cb, *next;
     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL;
 
     if (!test_bit(ev, cpu->plugin_mask)) {
         return;
     }
 
     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
         qemu_plugin_vcpu_syscall_cb_t func = cb->f.vcpu_syscall;
 
         func(cb->ctx->id, cpu->cpu_index, num, a1, a2, a3, a4, a5, a6, a7, a8);
     }
 }
 
 /*
  * Disable CFI checks.
  * The callback function has been loaded from an external library so we do not
  * have type information
  */
 QEMU_DISABLE_CFI
 void qemu_plugin_vcpu_syscall_ret(CPUState *cpu, int64_t num, int64_t ret)
 {
     struct qemu_plugin_cb *cb, *next;
     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL_RET;
 
     if (!test_bit(ev, cpu->plugin_mask)) {
         return;
     }
 
     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
         qemu_plugin_vcpu_syscall_ret_cb_t func = cb->f.vcpu_syscall_ret;
 
         func(cb->ctx->id, cpu->cpu_index, num, ret);
     }
 }
 
 void qemu_plugin_vcpu_idle_cb(CPUState *cpu)
 {
     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_IDLE);
 }
 
 void qemu_plugin_vcpu_resume_cb(CPUState *cpu)
 {
     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_RESUME);
 }
 
 void qemu_plugin_register_vcpu_idle_cb(qemu_plugin_id_t id,
                                        qemu_plugin_vcpu_simple_cb_t cb)
 {
     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_IDLE, cb);
 }
 
 void qemu_plugin_register_vcpu_resume_cb(qemu_plugin_id_t id,
                                          qemu_plugin_vcpu_simple_cb_t cb)
 {
     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_RESUME, cb);
 }
 
 void qemu_plugin_register_flush_cb(qemu_plugin_id_t id,
                                    qemu_plugin_simple_cb_t cb)
 {
     plugin_register_cb(id, QEMU_PLUGIN_EV_FLUSH, cb);
 }
 
 static bool free_dyn_cb_arr(void *p, uint32_t h, void *userp)
 {
     g_array_free((GArray *) p, true);
     return true;
 }
 
 void qemu_plugin_flush_cb(void)
 {
     qht_iter_remove(&plugin.dyn_cb_arr_ht, free_dyn_cb_arr, NULL);
     qht_reset(&plugin.dyn_cb_arr_ht);
 
     plugin_cb__simple(QEMU_PLUGIN_EV_FLUSH);
 }
 
 void exec_inline_op(struct qemu_plugin_dyn_cb *cb)
 {
     uint64_t *val = cb->userp;
 
     switch (cb->inline_insn.op) {
     case QEMU_PLUGIN_INLINE_ADD_U64:
         *val += cb->inline_insn.imm;
         break;
     default:
         g_assert_not_reached();
     }
 }
 
 void qemu_plugin_vcpu_mem_cb(CPUState *cpu, uint64_t vaddr,
                              MemOpIdx oi, enum qemu_plugin_mem_rw rw)
 {
     GArray *arr = cpu->plugin_mem_cbs;
     size_t i;
 
     if (arr == NULL) {
         return;
     }
     for (i = 0; i < arr->len; i++) {
         struct qemu_plugin_dyn_cb *cb =
             &g_array_index(arr, struct qemu_plugin_dyn_cb, i);
 
         if (!(rw & cb->rw)) {
                 break;
         }
         switch (cb->type) {
         case PLUGIN_CB_REGULAR:
             cb->f.vcpu_mem(cpu->cpu_index, make_plugin_meminfo(oi, rw),
                            vaddr, cb->userp);
             break;
         case PLUGIN_CB_INLINE:
             exec_inline_op(cb);
             break;
         default:
             g_assert_not_reached();
         }
     }
 }
 
 void qemu_plugin_atexit_cb(void)
 {
     plugin_cb__udata(QEMU_PLUGIN_EV_ATEXIT);
 }
 
 void qemu_plugin_register_atexit_cb(qemu_plugin_id_t id,
                                     qemu_plugin_udata_cb_t cb,
                                     void *udata)
 {
     plugin_register_cb_udata(id, QEMU_PLUGIN_EV_ATEXIT, cb, udata);
 }
 
 /*
  * Handle exit from linux-user. Unlike the normal atexit() mechanism
  * we need to handle the clean-up manually as it's possible threads
  * are still running. We need to remove all callbacks from code
  * generation, flush the current translations and then we can safely
  * trigger the exit callbacks.
  */
 
 void qemu_plugin_user_exit(void)
 {
     enum qemu_plugin_event ev;
     CPUState *cpu;
 
     QEMU_LOCK_GUARD(&plugin.lock);
 
     start_exclusive();
 
     /* un-register all callbacks except the final AT_EXIT one */
     for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
         if (ev != QEMU_PLUGIN_EV_ATEXIT) {
             struct qemu_plugin_ctx *ctx;
             QTAILQ_FOREACH(ctx, &plugin.ctxs, entry) {
                 plugin_unregister_cb__locked(ctx, ev);
             }
         }
     }
 
     tb_flush(current_cpu);
 
     CPU_FOREACH(cpu) {
         qemu_plugin_disable_mem_helpers(cpu);
     }
 
     end_exclusive();
 
     /* now it's safe to handle the exit case */
     qemu_plugin_atexit_cb();
 }
 
 /*
  * Helpers for *-user to ensure locks are sane across fork() events.
  */
 
 void qemu_plugin_user_prefork_lock(void)
 {
     qemu_rec_mutex_lock(&plugin.lock);
 }
 
 void qemu_plugin_user_postfork(bool is_child)
 {
     if (is_child) {
         /* should we just reset via plugin_init? */
         qemu_rec_mutex_init(&plugin.lock);
     } else {
         qemu_rec_mutex_unlock(&plugin.lock);
     }
 }
 
 
 /*
  * Call this function after longjmp'ing to the main loop. It's possible that the
  * last instruction of a TB might have used helpers, and therefore the
  * "disable" instruction will never execute because it ended up as dead code.
  */
 void qemu_plugin_disable_mem_helpers(CPUState *cpu)
 {
     cpu->plugin_mem_cbs = NULL;
 }
 
 static bool plugin_dyn_cb_arr_cmp(const void *ap, const void *bp)
 {
     return ap == bp;
 }
 
 static void __attribute__((__constructor__)) plugin_init(void)
 {
     int i;
 
     for (i = 0; i < QEMU_PLUGIN_EV_MAX; i++) {
         QLIST_INIT(&plugin.cb_lists[i]);
     }
     qemu_rec_mutex_init(&plugin.lock);
     plugin.id_ht = g_hash_table_new(g_int64_hash, g_int64_equal);
     plugin.cpu_ht = g_hash_table_new(g_int_hash, g_int_equal);
     QTAILQ_INIT(&plugin.ctxs);
     qht_init(&plugin.dyn_cb_arr_ht, plugin_dyn_cb_arr_cmp, 16,
              QHT_MODE_AUTO_RESIZE);
     atexit(qemu_plugin_atexit_cb);
 }