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.h"
  18
  19 static void gen_io_start(void)
  20 {
  21     tcg_gen_st_i32(tcg_constant_i32(1), cpu_env,
  22                    offsetof(ArchCPU, parent_obj.can_do_io) -
  23                    offsetof(ArchCPU, env));
  24 }
  25
  26 bool translator_io_start(DisasContextBase *db)
  27 {
  28     uint32_t cflags = tb_cflags(db->tb);
  29
  30     if (!(cflags & CF_USE_ICOUNT)) {
  31         return false;
  32     }
  33     if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
  34         /* Already started in translator_loop. */
  35         return true;
  36     }
  37
  38     gen_io_start();
  39
  40     /*
  41      * Ensure that this instruction will be the last in the TB.
  42      * The target may override this to something more forceful.
  43      */
  44     if (db->is_jmp == DISAS_NEXT) {
  45         db->is_jmp = DISAS_TOO_MANY;
  46     }
  47     return true;
  48 }
  49
  50 static TCGOp *gen_tb_start(uint32_t cflags)
  51 {
  52     TCGv_i32 count = tcg_temp_new_i32();
  53     TCGOp *icount_start_insn = NULL;
  54
  55     tcg_gen_ld_i32(count, cpu_env,
  56                    offsetof(ArchCPU, neg.icount_decr.u32) -
  57                    offsetof(ArchCPU, env));
  58
  59     if (cflags & CF_USE_ICOUNT) {
  60         /*
  61          * We emit a sub with a dummy immediate argument. Keep the insn index
  62          * of the sub so that we later (when we know the actual insn count)
  63          * can update the argument with the actual insn count.
  64          */
  65         tcg_gen_sub_i32(count, count, tcg_constant_i32(0));
  66         icount_start_insn = tcg_last_op();
  67     }
  68
  69     /*
  70      * Emit the check against icount_decr.u32 to see if we should exit
  71      * unless we suppress the check with CF_NOIRQ. If we are using
  72      * icount and have suppressed interruption the higher level code
  73      * should have ensured we don't run more instructions than the
  74      * budget.
  75      */
  76     if (cflags & CF_NOIRQ) {
  77         tcg_ctx->exitreq_label = NULL;
  78     } else {
  79         tcg_ctx->exitreq_label = gen_new_label();
  80         tcg_gen_brcondi_i32(TCG_COND_LT, count, 0, tcg_ctx->exitreq_label);
  81     }
  82
  83     if (cflags & CF_USE_ICOUNT) {
  84         tcg_gen_st16_i32(count, cpu_env,
  85                          offsetof(ArchCPU, neg.icount_decr.u16.low) -
  86                          offsetof(ArchCPU, env));
  87         /*
  88          * cpu->can_do_io is cleared automatically here at the beginning of
  89          * each translation block.  The cost is minimal and only paid for
  90          * -icount, plus it would be very easy to forget doing it in the
  91          * translator. Doing it here means we don't need a gen_io_end() to
  92          * go with gen_io_start().
  93          */
  94         tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
  95                        offsetof(ArchCPU, parent_obj.can_do_io) -
  96                        offsetof(ArchCPU, env));
  97     }
  98
  99     return icount_start_insn;
 100 }
 101
 102 static void gen_tb_end(const TranslationBlock *tb, uint32_t cflags,
 103                        TCGOp *icount_start_insn, int num_insns)
 104 {
 105     if (cflags & CF_USE_ICOUNT) {
 106         /*
 107          * Update the num_insn immediate parameter now that we know
 108          * the actual insn count.
 109          */
 110         tcg_set_insn_param(icount_start_insn, 2,
 111                            tcgv_i32_arg(tcg_constant_i32(num_insns)));
 112     }
 113
 114     if (tcg_ctx->exitreq_label) {
 115         gen_set_label(tcg_ctx->exitreq_label);
 116         tcg_gen_exit_tb(tb, TB_EXIT_REQUESTED);
 117     }
 118 }
 119
 120 bool translator_use_goto_tb(DisasContextBase *db, vaddr dest)
 121 {
 122     /* Suppress goto_tb if requested. */
 123     if (tb_cflags(db->tb) & CF_NO_GOTO_TB) {
 124         return false;
 125     }
 126
 127     /* Check for the dest on the same page as the start of the TB.  */
 128     return ((db->pc_first ^ dest) & TARGET_PAGE_MASK) == 0;
 129 }
 130
 131 void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
 132                      vaddr pc, void *host_pc, const TranslatorOps *ops,
 133                      DisasContextBase *db)
 134 {
 135     uint32_t cflags = tb_cflags(tb);
 136     TCGOp *icount_start_insn;
 137     bool plugin_enabled;
 138
 139     /* Initialize DisasContext */
 140     db->tb = tb;
 141     db->pc_first = pc;
 142     db->pc_next = pc;
 143     db->is_jmp = DISAS_NEXT;
 144     db->num_insns = 0;
 145     db->max_insns = *max_insns;
 146     db->singlestep_enabled = cflags & CF_SINGLE_STEP;
 147     db->host_addr[0] = host_pc;
 148     db->host_addr[1] = NULL;
 149
 150     ops->init_disas_context(db, cpu);
 151     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 152
 153     /* Start translating.  */
 154     icount_start_insn = gen_tb_start(cflags);
 155     ops->tb_start(db, cpu);
 156     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 157
 158     plugin_enabled = plugin_gen_tb_start(cpu, db, cflags & CF_MEMI_ONLY);
 159
 160     while (true) {
 161         *max_insns = ++db->num_insns;
 162         ops->insn_start(db, cpu);
 163         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 164
 165         if (plugin_enabled) {
 166             plugin_gen_insn_start(cpu, db);
 167         }
 168
 169         /* Disassemble one instruction.  The translate_insn hook should
 170            update db->pc_next and db->is_jmp to indicate what should be
 171            done next -- either exiting this loop or locate the start of
 172            the next instruction.  */
 173         if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
 174             /* Accept I/O on the last instruction.  */
 175             gen_io_start();
 176             ops->translate_insn(db, cpu);
 177         } else {
 178             /* we should only see CF_MEMI_ONLY for io_recompile */
 179             tcg_debug_assert(!(cflags & CF_MEMI_ONLY));
 180             ops->translate_insn(db, cpu);
 181         }
 182
 183         /*
 184          * We can't instrument after instructions that change control
 185          * flow although this only really affects post-load operations.
 186          *
 187          * Calling plugin_gen_insn_end() before we possibly stop translation
 188          * is important. Even if this ends up as dead code, plugin generation
 189          * needs to see a matching plugin_gen_insn_{start,end}() pair in order
 190          * to accurately track instrumented helpers that might access memory.
 191          */
 192         if (plugin_enabled) {
 193             plugin_gen_insn_end();
 194         }
 195
 196         /* Stop translation if translate_insn so indicated.  */
 197         if (db->is_jmp != DISAS_NEXT) {
 198             break;
 199         }
 200
 201         /* Stop translation if the output buffer is full,
 202            or we have executed all of the allowed instructions.  */
 203         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 204             db->is_jmp = DISAS_TOO_MANY;
 205             break;
 206         }
 207     }
 208
 209     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 210     ops->tb_stop(db, cpu);
 211     gen_tb_end(tb, cflags, icount_start_insn, db->num_insns);
 212
 213     if (plugin_enabled) {
 214         plugin_gen_tb_end(cpu);
 215     }
 216
 217     /* The disas_log hook may use these values rather than recompute.  */
 218     tb->size = db->pc_next - db->pc_first;
 219     tb->icount = db->num_insns;
 220
 221     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 222         && qemu_log_in_addr_range(db->pc_first)) {
 223         FILE *logfile = qemu_log_trylock();
 224         if (logfile) {
 225             fprintf(logfile, "----------------\n");
 226             ops->disas_log(db, cpu, logfile);
 227             fprintf(logfile, "\n");
 228             qemu_log_unlock(logfile);
 229         }
 230     }
 231 }
 232
 233 static void *translator_access(CPUArchState *env, DisasContextBase *db,
 234                                vaddr pc, size_t len)
 235 {
 236     void *host;
 237     vaddr base, end;
 238     TranslationBlock *tb;
 239
 240     tb = db->tb;
 241
 242     /* Use slow path if first page is MMIO. */
 243     if (unlikely(tb_page_addr0(tb) == -1)) {
 244         return NULL;
 245     }
 246
 247     end = pc + len - 1;
 248     if (likely(is_same_page(db, end))) {
 249         host = db->host_addr[0];
 250         base = db->pc_first;
 251     } else {
 252         host = db->host_addr[1];
 253         base = TARGET_PAGE_ALIGN(db->pc_first);
 254         if (host == NULL) {
 255             tb_page_addr_t page0, old_page1, new_page1;
 256
 257             new_page1 = get_page_addr_code_hostp(env, base, &db->host_addr[1]);
 258
 259             /*
 260              * If the second page is MMIO, treat as if the first page
 261              * was MMIO as well, so that we do not cache the TB.
 262              */
 263             if (unlikely(new_page1 == -1)) {
 264                 tb_unlock_pages(tb);
 265                 tb_set_page_addr0(tb, -1);
 266                 return NULL;
 267             }
 268
 269             /*
 270              * If this is not the first time around, and page1 matches,
 271              * then we already have the page locked.  Alternately, we're
 272              * not doing anything to prevent the PTE from changing, so
 273              * we might wind up with a different page, requiring us to
 274              * re-do the locking.
 275              */
 276             old_page1 = tb_page_addr1(tb);
 277             if (likely(new_page1 != old_page1)) {
 278                 page0 = tb_page_addr0(tb);
 279                 if (unlikely(old_page1 != -1)) {
 280                     tb_unlock_page1(page0, old_page1);
 281                 }
 282                 tb_set_page_addr1(tb, new_page1);
 283                 tb_lock_page1(page0, new_page1);
 284             }
 285             host = db->host_addr[1];
 286         }
 287
 288         /* Use slow path when crossing pages. */
 289         if (is_same_page(db, pc)) {
 290             return NULL;
 291         }
 292     }
 293
 294     tcg_debug_assert(pc >= base);
 295     return host + (pc - base);
 296 }
 297
 298 static void plugin_insn_append(abi_ptr pc, const void *from, size_t size)
 299 {
 300 #ifdef CONFIG_PLUGIN
 301     struct qemu_plugin_insn *insn = tcg_ctx->plugin_insn;
 302     abi_ptr off;
 303
 304     if (insn == NULL) {
 305         return;
 306     }
 307     off = pc - insn->vaddr;
 308     if (off < insn->data->len) {
 309         g_byte_array_set_size(insn->data, off);
 310     } else if (off > insn->data->len) {
 311         /* we have an unexpected gap */
 312         g_assert_not_reached();
 313     }
 314
 315     insn->data = g_byte_array_append(insn->data, from, size);
 316 #endif
 317 }
 318
 319 uint8_t translator_ldub(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 320 {
 321     uint8_t ret;
 322     void *p = translator_access(env, db, pc, sizeof(ret));
 323
 324     if (p) {
 325         plugin_insn_append(pc, p, sizeof(ret));
 326         return ldub_p(p);
 327     }
 328     ret = cpu_ldub_code(env, pc);
 329     plugin_insn_append(pc, &ret, sizeof(ret));
 330     return ret;
 331 }
 332
 333 uint16_t translator_lduw(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 334 {
 335     uint16_t ret, plug;
 336     void *p = translator_access(env, db, pc, sizeof(ret));
 337
 338     if (p) {
 339         plugin_insn_append(pc, p, sizeof(ret));
 340         return lduw_p(p);
 341     }
 342     ret = cpu_lduw_code(env, pc);
 343     plug = tswap16(ret);
 344     plugin_insn_append(pc, &plug, sizeof(ret));
 345     return ret;
 346 }
 347
 348 uint32_t translator_ldl(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 349 {
 350     uint32_t ret, plug;
 351     void *p = translator_access(env, db, pc, sizeof(ret));
 352
 353     if (p) {
 354         plugin_insn_append(pc, p, sizeof(ret));
 355         return ldl_p(p);
 356     }
 357     ret = cpu_ldl_code(env, pc);
 358     plug = tswap32(ret);
 359     plugin_insn_append(pc, &plug, sizeof(ret));
 360     return ret;
 361 }
 362
 363 uint64_t translator_ldq(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 364 {
 365     uint64_t ret, plug;
 366     void *p = translator_access(env, db, pc, sizeof(ret));
 367
 368     if (p) {
 369         plugin_insn_append(pc, p, sizeof(ret));
 370         return ldq_p(p);
 371     }
 372     ret = cpu_ldq_code(env, pc);
 373     plug = tswap64(ret);
 374     plugin_insn_append(pc, &plug, sizeof(ret));
 375     return ret;
 376 }
 377
 378 void translator_fake_ldb(uint8_t insn8, abi_ptr pc)
 379 {
 380     plugin_insn_append(pc, &insn8, sizeof(insn8));
 381 }