accel/tcg/translator.c

   1 /*
   2  * Generic intermediate code generation.
   3  *
   4  * Copyright (C) 2016-2017 Lluís Vilanova <vilanova@ac.upc.edu>
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   7  * See the COPYING file in the top-level directory.
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "qemu/log.h"
  12 #include "qemu/error-report.h"
  13 #include "exec/exec-all.h"
  14 #include "exec/translator.h"
  15 #include "exec/plugin-gen.h"
  16 #include "tcg/tcg-op-common.h"
  17 #include "internal-target.h"
  18
  19 static void set_can_do_io(DisasContextBase *db, bool val)
  20 {
  21     QEMU_BUILD_BUG_ON(sizeof_field(CPUState, neg.can_do_io) != 1);
  22     tcg_gen_st8_i32(tcg_constant_i32(val), tcg_env,
  23                     offsetof(ArchCPU, parent_obj.neg.can_do_io) -
  24                     offsetof(ArchCPU, env));
  25 }
  26
  27 bool translator_io_start(DisasContextBase *db)
  28 {
  29     /*
  30      * Ensure that this instruction will be the last in the TB.
  31      * The target may override this to something more forceful.
  32      */
  33     if (db->is_jmp == DISAS_NEXT) {
  34         db->is_jmp = DISAS_TOO_MANY;
  35     }
  36     return true;
  37 }
  38
  39 static TCGOp *gen_tb_start(DisasContextBase *db, uint32_t cflags)
  40 {
  41     TCGv_i32 count = NULL;
  42     TCGOp *icount_start_insn = NULL;
  43
  44     if ((cflags & CF_USE_ICOUNT) || !(cflags & CF_NOIRQ)) {
  45         count = tcg_temp_new_i32();
  46         tcg_gen_ld_i32(count, tcg_env,
  47                        offsetof(ArchCPU, parent_obj.neg.icount_decr.u32)
  48                        - offsetof(ArchCPU, env));
  49     }
  50
  51     if (cflags & CF_USE_ICOUNT) {
  52         /*
  53          * We emit a sub with a dummy immediate argument. Keep the insn index
  54          * of the sub so that we later (when we know the actual insn count)
  55          * can update the argument with the actual insn count.
  56          */
  57         tcg_gen_sub_i32(count, count, tcg_constant_i32(0));
  58         icount_start_insn = tcg_last_op();
  59     }
  60
  61     /*
  62      * Emit the check against icount_decr.u32 to see if we should exit
  63      * unless we suppress the check with CF_NOIRQ. If we are using
  64      * icount and have suppressed interruption the higher level code
  65      * should have ensured we don't run more instructions than the
  66      * budget.
  67      */
  68     if (cflags & CF_NOIRQ) {
  69         tcg_ctx->exitreq_label = NULL;
  70     } else {
  71         tcg_ctx->exitreq_label = gen_new_label();
  72         tcg_gen_brcondi_i32(TCG_COND_LT, count, 0, tcg_ctx->exitreq_label);
  73     }
  74
  75     if (cflags & CF_USE_ICOUNT) {
  76         tcg_gen_st16_i32(count, tcg_env,
  77                          offsetof(ArchCPU, parent_obj.neg.icount_decr.u16.low)
  78                          - offsetof(ArchCPU, env));
  79     }
  80
  81     return icount_start_insn;
  82 }
  83
  84 static void gen_tb_end(const TranslationBlock *tb, uint32_t cflags,
  85                        TCGOp *icount_start_insn, int num_insns)
  86 {
  87     if (cflags & CF_USE_ICOUNT) {
  88         /*
  89          * Update the num_insn immediate parameter now that we know
  90          * the actual insn count.
  91          */
  92         tcg_set_insn_param(icount_start_insn, 2,
  93                            tcgv_i32_arg(tcg_constant_i32(num_insns)));
  94     }
  95
  96     if (tcg_ctx->exitreq_label) {
  97         gen_set_label(tcg_ctx->exitreq_label);
  98         tcg_gen_exit_tb(tb, TB_EXIT_REQUESTED);
  99     }
 100 }
 101
 102 bool translator_use_goto_tb(DisasContextBase *db, vaddr dest)
 103 {
 104     /* Suppress goto_tb if requested. */
 105     if (tb_cflags(db->tb) & CF_NO_GOTO_TB) {
 106         return false;
 107     }
 108
 109     /* Check for the dest on the same page as the start of the TB.  */
 110     return ((db->pc_first ^ dest) & TARGET_PAGE_MASK) == 0;
 111 }
 112
 113 void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
 114                      vaddr pc, void *host_pc, const TranslatorOps *ops,
 115                      DisasContextBase *db)
 116 {
 117     uint32_t cflags = tb_cflags(tb);
 118     TCGOp *icount_start_insn;
 119     TCGOp *first_insn_start = NULL;
 120     bool plugin_enabled;
 121
 122     /* Initialize DisasContext */
 123     db->tb = tb;
 124     db->pc_first = pc;
 125     db->pc_next = pc;
 126     db->is_jmp = DISAS_NEXT;
 127     db->num_insns = 0;
 128     db->max_insns = *max_insns;
 129     db->singlestep_enabled = cflags & CF_SINGLE_STEP;
 130     db->insn_start = NULL;
 131     db->host_addr[0] = host_pc;
 132     db->host_addr[1] = NULL;
 133
 134     ops->init_disas_context(db, cpu);
 135     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 136
 137     /* Start translating.  */
 138     icount_start_insn = gen_tb_start(db, cflags);
 139     ops->tb_start(db, cpu);
 140     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 141
 142     plugin_enabled = plugin_gen_tb_start(cpu, db, cflags & CF_MEMI_ONLY);
 143     db->plugin_enabled = plugin_enabled;
 144
 145     while (true) {
 146         *max_insns = ++db->num_insns;
 147         ops->insn_start(db, cpu);
 148         db->insn_start = tcg_last_op();
 149         if (first_insn_start == NULL) {
 150             first_insn_start = db->insn_start;
 151         }
 152         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 153
 154         if (plugin_enabled) {
 155             plugin_gen_insn_start(cpu, db);
 156         }
 157
 158         /*
 159          * Disassemble one instruction.  The translate_insn hook should
 160          * update db->pc_next and db->is_jmp to indicate what should be
 161          * done next -- either exiting this loop or locate the start of
 162          * the next instruction.
 163          */
 164         ops->translate_insn(db, cpu);
 165
 166         /*
 167          * We can't instrument after instructions that change control
 168          * flow although this only really affects post-load operations.
 169          *
 170          * Calling plugin_gen_insn_end() before we possibly stop translation
 171          * is important. Even if this ends up as dead code, plugin generation
 172          * needs to see a matching plugin_gen_insn_{start,end}() pair in order
 173          * to accurately track instrumented helpers that might access memory.
 174          */
 175         if (plugin_enabled) {
 176             plugin_gen_insn_end();
 177         }
 178
 179         /* Stop translation if translate_insn so indicated.  */
 180         if (db->is_jmp != DISAS_NEXT) {
 181             break;
 182         }
 183
 184         /* Stop translation if the output buffer is full,
 185            or we have executed all of the allowed instructions.  */
 186         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 187             db->is_jmp = DISAS_TOO_MANY;
 188             break;
 189         }
 190     }
 191
 192     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 193     ops->tb_stop(db, cpu);
 194     gen_tb_end(tb, cflags, icount_start_insn, db->num_insns);
 195
 196     /*
 197      * Manage can_do_io for the translation block: set to false before
 198      * the first insn and set to true before the last insn.
 199      */
 200     if (db->num_insns == 1) {
 201         tcg_debug_assert(first_insn_start == db->insn_start);
 202     } else {
 203         tcg_debug_assert(first_insn_start != db->insn_start);
 204         tcg_ctx->emit_before_op = first_insn_start;
 205         set_can_do_io(db, false);
 206     }
 207     tcg_ctx->emit_before_op = db->insn_start;
 208     set_can_do_io(db, true);
 209     tcg_ctx->emit_before_op = NULL;
 210
 211     if (plugin_enabled) {
 212         plugin_gen_tb_end(cpu, db->num_insns);
 213     }
 214
 215     /* The disas_log hook may use these values rather than recompute.  */
 216     tb->size = db->pc_next - db->pc_first;
 217     tb->icount = db->num_insns;
 218
 219     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 220         && qemu_log_in_addr_range(db->pc_first)) {
 221         FILE *logfile = qemu_log_trylock();
 222         if (logfile) {
 223             fprintf(logfile, "----------------\n");
 224             ops->disas_log(db, cpu, logfile);
 225             fprintf(logfile, "\n");
 226             qemu_log_unlock(logfile);
 227         }
 228     }
 229 }
 230
 231 static void *translator_access(CPUArchState *env, DisasContextBase *db,
 232                                vaddr pc, size_t len)
 233 {
 234     void *host;
 235     vaddr base, end;
 236     TranslationBlock *tb;
 237
 238     tb = db->tb;
 239
 240     /* Use slow path if first page is MMIO. */
 241     if (unlikely(tb_page_addr0(tb) == -1)) {
 242         return NULL;
 243     }
 244
 245     end = pc + len - 1;
 246     if (likely(is_same_page(db, end))) {
 247         host = db->host_addr[0];
 248         base = db->pc_first;
 249     } else {
 250         host = db->host_addr[1];
 251         base = TARGET_PAGE_ALIGN(db->pc_first);
 252         if (host == NULL) {
 253             tb_page_addr_t page0, old_page1, new_page1;
 254
 255             new_page1 = get_page_addr_code_hostp(env, base, &db->host_addr[1]);
 256
 257             /*
 258              * If the second page is MMIO, treat as if the first page
 259              * was MMIO as well, so that we do not cache the TB.
 260              */
 261             if (unlikely(new_page1 == -1)) {
 262                 tb_unlock_pages(tb);
 263                 tb_set_page_addr0(tb, -1);
 264                 return NULL;
 265             }
 266
 267             /*
 268              * If this is not the first time around, and page1 matches,
 269              * then we already have the page locked.  Alternately, we're
 270              * not doing anything to prevent the PTE from changing, so
 271              * we might wind up with a different page, requiring us to
 272              * re-do the locking.
 273              */
 274             old_page1 = tb_page_addr1(tb);
 275             if (likely(new_page1 != old_page1)) {
 276                 page0 = tb_page_addr0(tb);
 277                 if (unlikely(old_page1 != -1)) {
 278                     tb_unlock_page1(page0, old_page1);
 279                 }
 280                 tb_set_page_addr1(tb, new_page1);
 281                 tb_lock_page1(page0, new_page1);
 282             }
 283             host = db->host_addr[1];
 284         }
 285
 286         /* Use slow path when crossing pages. */
 287         if (is_same_page(db, pc)) {
 288             return NULL;
 289         }
 290     }
 291
 292     tcg_debug_assert(pc >= base);
 293     return host + (pc - base);
 294 }
 295
 296 static void plugin_insn_append(abi_ptr pc, const void *from, size_t size)
 297 {
 298 #ifdef CONFIG_PLUGIN
 299     struct qemu_plugin_insn *insn = tcg_ctx->plugin_insn;
 300     abi_ptr off;
 301
 302     if (insn == NULL) {
 303         return;
 304     }
 305     off = pc - insn->vaddr;
 306     if (off < insn->data->len) {
 307         g_byte_array_set_size(insn->data, off);
 308     } else if (off > insn->data->len) {
 309         /* we have an unexpected gap */
 310         g_assert_not_reached();
 311     }
 312
 313     insn->data = g_byte_array_append(insn->data, from, size);
 314 #endif
 315 }
 316
 317 uint8_t translator_ldub(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 318 {
 319     uint8_t ret;
 320     void *p = translator_access(env, db, pc, sizeof(ret));
 321
 322     if (p) {
 323         plugin_insn_append(pc, p, sizeof(ret));
 324         return ldub_p(p);
 325     }
 326     ret = cpu_ldub_code(env, pc);
 327     plugin_insn_append(pc, &ret, sizeof(ret));
 328     return ret;
 329 }
 330
 331 uint16_t translator_lduw(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 332 {
 333     uint16_t ret, plug;
 334     void *p = translator_access(env, db, pc, sizeof(ret));
 335
 336     if (p) {
 337         plugin_insn_append(pc, p, sizeof(ret));
 338         return lduw_p(p);
 339     }
 340     ret = cpu_lduw_code(env, pc);
 341     plug = tswap16(ret);
 342     plugin_insn_append(pc, &plug, sizeof(ret));
 343     return ret;
 344 }
 345
 346 uint32_t translator_ldl(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 347 {
 348     uint32_t ret, plug;
 349     void *p = translator_access(env, db, pc, sizeof(ret));
 350
 351     if (p) {
 352         plugin_insn_append(pc, p, sizeof(ret));
 353         return ldl_p(p);
 354     }
 355     ret = cpu_ldl_code(env, pc);
 356     plug = tswap32(ret);
 357     plugin_insn_append(pc, &plug, sizeof(ret));
 358     return ret;
 359 }
 360
 361 uint64_t translator_ldq(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 362 {
 363     uint64_t ret, plug;
 364     void *p = translator_access(env, db, pc, sizeof(ret));
 365
 366     if (p) {
 367         plugin_insn_append(pc, p, sizeof(ret));
 368         return ldq_p(p);
 369     }
 370     ret = cpu_ldq_code(env, pc);
 371     plug = tswap64(ret);
 372     plugin_insn_append(pc, &plug, sizeof(ret));
 373     return ret;
 374 }
 375
 376 void translator_fake_ldb(uint8_t insn8, abi_ptr pc)
 377 {
 378     plugin_insn_append(pc, &insn8, sizeof(insn8));
 379 }