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/translate-all.h"
  16 #include "exec/plugin-gen.h"
  17 #include "tcg/tcg-op-common.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, target_ulong 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                      target_ulong pc, void *host_pc,
 133                      const TranslatorOps *ops, 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 #ifdef CONFIG_USER_ONLY
 151     page_protect(pc);
 152 #endif
 153
 154     ops->init_disas_context(db, cpu);
 155     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 156
 157     /* Start translating.  */
 158     icount_start_insn = gen_tb_start(cflags);
 159     ops->tb_start(db, cpu);
 160     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 161
 162     plugin_enabled = plugin_gen_tb_start(cpu, db, cflags & CF_MEMI_ONLY);
 163
 164     while (true) {
 165         *max_insns = ++db->num_insns;
 166         ops->insn_start(db, cpu);
 167         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
 168
 169         if (plugin_enabled) {
 170             plugin_gen_insn_start(cpu, db);
 171         }
 172
 173         /* Disassemble one instruction.  The translate_insn hook should
 174            update db->pc_next and db->is_jmp to indicate what should be
 175            done next -- either exiting this loop or locate the start of
 176            the next instruction.  */
 177         if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
 178             /* Accept I/O on the last instruction.  */
 179             gen_io_start();
 180             ops->translate_insn(db, cpu);
 181         } else {
 182             /* we should only see CF_MEMI_ONLY for io_recompile */
 183             tcg_debug_assert(!(cflags & CF_MEMI_ONLY));
 184             ops->translate_insn(db, cpu);
 185         }
 186
 187         /*
 188          * We can't instrument after instructions that change control
 189          * flow although this only really affects post-load operations.
 190          *
 191          * Calling plugin_gen_insn_end() before we possibly stop translation
 192          * is important. Even if this ends up as dead code, plugin generation
 193          * needs to see a matching plugin_gen_insn_{start,end}() pair in order
 194          * to accurately track instrumented helpers that might access memory.
 195          */
 196         if (plugin_enabled) {
 197             plugin_gen_insn_end();
 198         }
 199
 200         /* Stop translation if translate_insn so indicated.  */
 201         if (db->is_jmp != DISAS_NEXT) {
 202             break;
 203         }
 204
 205         /* Stop translation if the output buffer is full,
 206            or we have executed all of the allowed instructions.  */
 207         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 208             db->is_jmp = DISAS_TOO_MANY;
 209             break;
 210         }
 211     }
 212
 213     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 214     ops->tb_stop(db, cpu);
 215     gen_tb_end(tb, cflags, icount_start_insn, db->num_insns);
 216
 217     if (plugin_enabled) {
 218         plugin_gen_tb_end(cpu);
 219     }
 220
 221     /* The disas_log hook may use these values rather than recompute.  */
 222     tb->size = db->pc_next - db->pc_first;
 223     tb->icount = db->num_insns;
 224
 225     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 226         && qemu_log_in_addr_range(db->pc_first)) {
 227         FILE *logfile = qemu_log_trylock();
 228         if (logfile) {
 229             fprintf(logfile, "----------------\n");
 230             ops->disas_log(db, cpu, logfile);
 231             fprintf(logfile, "\n");
 232             qemu_log_unlock(logfile);
 233         }
 234     }
 235 }
 236
 237 static void *translator_access(CPUArchState *env, DisasContextBase *db,
 238                                target_ulong pc, size_t len)
 239 {
 240     void *host;
 241     target_ulong base, end;
 242     TranslationBlock *tb;
 243
 244     tb = db->tb;
 245
 246     /* Use slow path if first page is MMIO. */
 247     if (unlikely(tb_page_addr0(tb) == -1)) {
 248         return NULL;
 249     }
 250
 251     end = pc + len - 1;
 252     if (likely(is_same_page(db, end))) {
 253         host = db->host_addr[0];
 254         base = db->pc_first;
 255     } else {
 256         host = db->host_addr[1];
 257         base = TARGET_PAGE_ALIGN(db->pc_first);
 258         if (host == NULL) {
 259             tb_page_addr_t phys_page =
 260                 get_page_addr_code_hostp(env, base, &db->host_addr[1]);
 261
 262             /*
 263              * If the second page is MMIO, treat as if the first page
 264              * was MMIO as well, so that we do not cache the TB.
 265              */
 266             if (unlikely(phys_page == -1)) {
 267                 tb_set_page_addr0(tb, -1);
 268                 return NULL;
 269             }
 270
 271             tb_set_page_addr1(tb, phys_page);
 272 #ifdef CONFIG_USER_ONLY
 273             page_protect(end);
 274 #endif
 275             host = db->host_addr[1];
 276         }
 277
 278         /* Use slow path when crossing pages. */
 279         if (is_same_page(db, pc)) {
 280             return NULL;
 281         }
 282     }
 283
 284     tcg_debug_assert(pc >= base);
 285     return host + (pc - base);
 286 }
 287
 288 static void plugin_insn_append(abi_ptr pc, const void *from, size_t size)
 289 {
 290 #ifdef CONFIG_PLUGIN
 291     struct qemu_plugin_insn *insn = tcg_ctx->plugin_insn;
 292     abi_ptr off;
 293
 294     if (insn == NULL) {
 295         return;
 296     }
 297     off = pc - insn->vaddr;
 298     if (off < insn->data->len) {
 299         g_byte_array_set_size(insn->data, off);
 300     } else if (off > insn->data->len) {
 301         /* we have an unexpected gap */
 302         g_assert_not_reached();
 303     }
 304
 305     insn->data = g_byte_array_append(insn->data, from, size);
 306 #endif
 307 }
 308
 309 uint8_t translator_ldub(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 310 {
 311     uint8_t ret;
 312     void *p = translator_access(env, db, pc, sizeof(ret));
 313
 314     if (p) {
 315         plugin_insn_append(pc, p, sizeof(ret));
 316         return ldub_p(p);
 317     }
 318     ret = cpu_ldub_code(env, pc);
 319     plugin_insn_append(pc, &ret, sizeof(ret));
 320     return ret;
 321 }
 322
 323 uint16_t translator_lduw(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 324 {
 325     uint16_t ret, plug;
 326     void *p = translator_access(env, db, pc, sizeof(ret));
 327
 328     if (p) {
 329         plugin_insn_append(pc, p, sizeof(ret));
 330         return lduw_p(p);
 331     }
 332     ret = cpu_lduw_code(env, pc);
 333     plug = tswap16(ret);
 334     plugin_insn_append(pc, &plug, sizeof(ret));
 335     return ret;
 336 }
 337
 338 uint32_t translator_ldl(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 339 {
 340     uint32_t ret, plug;
 341     void *p = translator_access(env, db, pc, sizeof(ret));
 342
 343     if (p) {
 344         plugin_insn_append(pc, p, sizeof(ret));
 345         return ldl_p(p);
 346     }
 347     ret = cpu_ldl_code(env, pc);
 348     plug = tswap32(ret);
 349     plugin_insn_append(pc, &plug, sizeof(ret));
 350     return ret;
 351 }
 352
 353 uint64_t translator_ldq(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
 354 {
 355     uint64_t ret, plug;
 356     void *p = translator_access(env, db, pc, sizeof(ret));
 357
 358     if (p) {
 359         plugin_insn_append(pc, p, sizeof(ret));
 360         return ldq_p(p);
 361     }
 362     ret = cpu_ldq_code(env, pc);
 363     plug = tswap64(ret);
 364     plugin_insn_append(pc, &plug, sizeof(ret));
 365     return ret;
 366 }
 367
 368 void translator_fake_ldb(uint8_t insn8, abi_ptr pc)
 369 {
 370     plugin_insn_append(pc, &insn8, sizeof(insn8));
 371 }